Frequency dependence of hysteresis curves in 'non-conducting' magnetic materials
D. C. Jiles
1993-01-01
The problem of modeling the frequency dependence of hysteresis in magnetic materials is approached in a new way. The DC magnetization curve, or hysteresis loop, is assumed to be the equilibrium position for the bulk magnetization. All microscopic processes which occur under the action of a time-varying field can be averaged to give a time dependent displacement from the equilibrium,
NASA Astrophysics Data System (ADS)
Fujisaki, Keisuke; Liu, Sungju
2014-05-01
The influence of power semiconductor characteristic in Pulse-width-modulation (PWM) inverter on the magnetic hysteresis curve in silicon steel is discussed through the measured magnetic hysteresis curves. The magnetic hysteresis curve of PWM inverter-fed silicon steel has a lot of minor loops as closed loops and open loops, which make an influence on the iron loss. Two shapes of minor loops are found to be caused by the voltage shifts and they are derived from the on-voltage of the semiconductors in PWM inverter circuit. Therefore, it is concluded that the power-semiconductor characteristic in PWM inverter makes an influence on the magnetic hysteresis curve in silicon steel.
perature sensitive. Both electrode pairs show approximately the same thermal hysteresis.
Mandelis, Andreas
. A. In "Ion-Selective Electrodes in Analytical Chemistry"; Freiser, H., Ed.; Plenum: New York, 1978 n "Ion-Seiectlve Electrodes"; Durst, R. A,, Ed.; National Bureauof Standards: Washington, DC, NBS236 perature sensitive. Both electrode pairs show approximately the same thermal hysteresis. The E
Determination of dynamic release curves of manganin stress gauges from their resistive hysteresis
NASA Astrophysics Data System (ADS)
Rosenberg, Z.
1986-11-01
We extend our previous analytical modeling of the dynamic response of shock loaded piezoresistance gauges to the unloading region. We present a new approach in which we use the measured resistive hysteresis of manganin gauges to get their release stress-strain characteristics. This procedure is especially suited for manganin gauges because their resistive response depends only on the stresses and strains which prevail in them. Other gauge materials which are sensitive to the temperature rise and/or shock generated defects would not lend themselves to this direct analysis. We present an example in which we calculate the unloading stress-strain curve for manganin from a shock level of 120 kb down to zero longitudinal stress. Various aspects of this curve are discussed and compared to data obtained by other techniques.
NASA Astrophysics Data System (ADS)
Lu, Yiyun; Qin, Yujie; Dang, Qiaohong; Wang, Jiasu
2010-12-01
The crossing in magnetic levitation force-gap hysteresis curve of melt high-temperature superconductor (HTS) vs. NdFeB permanent magnet (PM) was experimentally studied. One HTS bulk and PM was used in the experiments. Four experimental methods were employed combining of high/low speed of movement of PM with/without heat insulation materials (HIM) enclosed respectively. Experimental results show that crossing of the levitation force-gap curve is related to experimental methods. A crossing occurs in the magnetic force-gap curve while the PM moves approaching to and departing from the sample with high or low speed of movement without HIM enclosed. When the PM is enclosed with HIM during the measurement procedures, there is no crossing in the force-gap curve no matter high speed or low speed of movement of the PM. It was found experimentally that, with the increase of the moving speed of the PM, the maximum magnitude of levitation force of the HTS increases also. The results are interpreted based on Maxwell theories and flux flow-creep models of HTS.
NASA Astrophysics Data System (ADS)
H, R. Hamedi; M, R. Mehmannavaz; Hadi, Afshari
2015-08-01
The effects of optical field on the phenomenon of optical bistability (OB) are investigated in a K-type semiconductor double quantum well (SDQW) under various parametric conditions. It is shown that the OB threshold can be manipulated by increasing the intensity of coupling field. The dependence of the shift of OB hysteresis curve on probe wavelength detuning is then explored. In order to demonstrate controllability of the OB in this SDQW, we compare the OB features of three different configurations which could arise in this SDQW scheme, i.e., K-type, Y-type, and inverted Y-type systems. The controllability of this semiconductor nanostructure medium makes the presented OB scheme more valuable for applications in all-optical switches, information storage, and logic circuits of all optical information processing. Project supported by the Lithuanian Research Council (Grant No. VP1-3.1-ŠM-01-V-03-001).
Mon. Not. R. Astron. Soc. 338, 189196 (2003) Hysteresis in the light curves of soft X-ray transients
Coppi, Paolo
2003-01-01
Mon. Not. R. Astron. Soc. 338, 189Â196 (2003) Hysteresis in the light curves of soft X-ray Â X-rays: binaries Â X-rays: individual: Aql X-1. 1 INTRODUCTION Soft X-ray transients (SXTs ABSTRACT Using Proportional Counter Array (PCA) data from the Rossi X-Ray Timing Explorer (RXTE), we track
60. SUPPORT CARRIAGE ASSEMBLY AT ISLIP CANYON SHOWING CURVED RAILS ...
60. SUPPORT CARRIAGE ASSEMBLY AT ISLIP CANYON SHOWING CURVED RAILS AND FLOATING BARGE IN BACKGROUND, February 16, 1948. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA
INTERIOR SHOWING DETAIL OF STRUCTURAL SYSTEM AND CONTINUOUS CURVE OF ...
INTERIOR SHOWING DETAIL OF STRUCTURAL SYSTEM AND CONTINUOUS CURVE OF WALL TO ROOF, VIEW FACING NORTHWEST. - Naval Air Station Barbers Point, Marine Corps Air Station Ewa Hangar, Cabot Road midway between Bismarck Sea & Vincon Roads, Ewa, Honolulu County, HI
Interior detail, building 810, view to north showing curved chord ...
Interior detail, building 810, view to north showing curved chord sections of roof trusses, 90mm lens plus electronic flash fill lighting. - Travis Air Force Base, B-36 Hangar, Between Woodskill Avenue & Ellis, adjacent to Taxiway V & W, Fairfield, Solano County, CA
View to southwest along bridge alignment, showing reverse curve from ...
View to southwest along bridge alignment, showing reverse curve from near deck level; Southern Pacific Railroad track passing beneath bridge; Western Pacific Railroad track out of sight behind bridge; photographer unknown; 1933 photo from collection of Office of Structures Maintenance, California Department of Transportation, Sacramento - Carroll Overhead Bridge, Altamont Pass Road, Livermore, Alameda County, CA
14. VIEW FROM TUNDRA CURVES (ON TRAIL RIDGE ROAD) SHOWING ...
14. VIEW FROM TUNDRA CURVES (ON TRAIL RIDGE ROAD) SHOWING FALL RIVER ROAD RISING FROM BENEATH CHAPIN PASS (AT EXTREME RIGHT) TO FALL RIVER PASS (FAR LEFT). - Fall River Road, Between Estes Park & Fall River Pass, Estes Park, Larimer County, CO
Influence of microstructural constituents on the hysteresis curves in 0.2%C and 0.45%C steels
NASA Astrophysics Data System (ADS)
Costa, L. F. T.; Girotto, F.; Baiotto, R.; Gerhardt, G.; de Campos, M. F.; Missell, F. P.
2011-07-01
Steels with 0.2% and 0.45%C were submitted to different types of heat treatment, leading to different microstructures, with different amounts of the microstructural constituents: ferrite, pearlite and martensite. Measurements of magnetic hysteresis and Barkhausen noise were performed at different frequencies. A relationship was found between coercive force and the volume fraction of the microstructural constituents. The influence of the microstructural constituents on the shape of hysteresis curve is also discussed. The presence of martensite leads to more magnetization reversal by domain rotation, reducing the relevance of domain wall movement as a reversal mechanism. When domain wall movement predominates, permeability increases and coercivity decreases. As a consequence, when the martensite volume fraction increases, coercivity also increases. The results help clarify the relation between microstructure of steels and Barkhausen noise measurements in non-destructive testing.
A digital hysteresis loop experiment
NASA Astrophysics Data System (ADS)
Francavilla, T. L.; Claassen, J. H.; Willard, M. A.
2013-10-01
A toroid with primary and secondary windings is used as a transformer to generate magnetic hysteresis curves. The primary winding is driven by a signal generator, which induces an alternating voltage in the secondary winding. Both input and output voltages are captured using a digital storage oscilloscope and processed to generate and display a hysteresis curve. We show such curves are representative of the material used as the transformer core. Data acquisition and processing steps are presented in a manner suitable for use in an undergraduate laboratory or lecture demonstration.
Chang, Hong; Wu, Haibin; Xie, Changde; Wang, Hai
2004-11-19
The dependence of the shift of an optical bistability hysteresis curve on the nonlinear phase shift induced by a controlling light is observed in a four-level atomic system of 87 Rb inside an optical ring cavity. In the process the intensity of the coupling beam keeps constant and the atomic system is operated at near conditions of coherent population trapping due to atomic coherence. The refractive and absorptive chi3 nonlinearities enhanced by atomic coherence provide the physical mechanism of the phenomena. Based on the effects, all-optical flip-flop and storage of optical pulse signals with a low peak power of several tens of microwatts are implemented. PMID:15601009
NASA Astrophysics Data System (ADS)
Perevertov, O.; Schäfer, R.
2014-05-01
The influence of applied tensile stress on the hysteresis curve and domain structure in conventional (1?1?0)[0?0?1] Fe-3%Si steel, cut parallel to the rolling direction, is studied on samples with different grain sizes. Quasistatic hysteresis loops under tensile stresses up to 70 MPa were measured. The magnetic domains and magnetization processes were observed by longitudinal Kerr microscopy at different levels of stress. It is shown that for stresses exceeding 5-10 MPa the bulk hysteresis loop can be described with good accuracy by the action of an effective field, which is the product of a function of stress and a function of magnetization. The function of stress is approximately linear with a slope of one. Except for the sample with the smallest grains, the function of magnetization is linear in the magnetization range ±1.2-1.5 T, i.e. it has a typical demagnetizing field shape. Domain observation reveals that the effective field is caused by the demagnetizing fields occurring at grain boundaries and at the sheet surface due to the removal of closure domains transverse to the rolling direction by the tensile stress. The closure structure reappears at higher fields. Another indirect indication of demagnetizing fields is the fact that the hysteresis losses drop continuously with stress and changes in the coercive force are small. The effective field of the sample with the smallest grains increases most nonlinearly with stress similar to the behaviour obtained for non-oriented material.
NASA Astrophysics Data System (ADS)
Perevertov, O.; Schäfer, R.
2012-04-01
The influence of an applied compressive stress on the hysteresis curve and domain structure in conventional (1?1?0) [0?0?1] Fe-3%Si steel cut transverse to the rolling direction is studied. Quasistatic hysteresis loops under compressive stress up to 75 MPa were measured. The magnetic domains and magnetization processes were observed by longitudinal Kerr microscopy at different levels of stress. It is shown that 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 observations have shown that the reasons for the effective field are demagnetizing fields due to the disappearance of supplementary domains along [0?1?0] and [1?0?0] at low fields and different domain systems in different grains at moderate fields. The latter are caused by differences in grain sensitivity to stress depending on the degree of misorientation. A decrease in the effective field above 1 T is connected with a transformation of all grains into the same domain system—the column pattern.
Hysteresis characterization using charge feedback control for a LIPCA device
NASA Astrophysics Data System (ADS)
Beck, James; Noras, Maciej; Kieres, Jerzy; Speich, John E.; Mossi, Karla M.; Leang, Kam K.
2006-03-01
In this paper, we study the no-load behavior of a lightweight piezo-composite curved actuator (LIPCA) subjected to voltage and charge control. First, we examine the effect of hysteresis and creep when the actuator is voltage controlled at a slow scan speed. The experimental results show that creep increases the displacement hysteresis by over 25% when scanning at 1/60 Hz. Afterwards, we discuss the design and implementation of a charge-feedback circuit to control the displacement of the actuator. The hysteresis curves between voltage- and charge-control modes are compared for the scan frequencies of 1 and 5 Hz. The results show that charge control (compared to voltage control) of a LIPCA device exhibits significantly less hysteresis, over 80% less.
90 3. RIEMANNIAN MANIFOLDS (d) Show that the curves , : R G given in these coordinates
Godinho, Leonor
vector v TpM, there exists a unique geodesic cv : I M defined on a maximal open interval I R geodesics; (ii) no geodesics. (h) Show that no open set U G is isometric to an open set V R2 such that 0 I, cv(0) = p and cv(0) = v. Consider now the curve : J M defined by (t) = cv(at), where a R
Plant thermal hysteresis proteins.
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
Stoleriu, Laurentiu; Chakraborty, Pradip; Hauser, Andreas; Enachescu, Cristian
2015-01-01
The recently obtained spin-crossover nanoparticles are possible candidates for applications in the recording media industry as materials for data storage, or as pressure and temperature sensors. For these applications the intermolecular interactions and interactions between spin-crossover nanoparticles are extremely important, as they may be essential factors in triggering the transition between the two stable phases: the high-spin and low-spin ones. In order to find correlations between the distributions in size and interactions and the transition temperatures distribution, we apply the FORC (First Order Reversal Curves) method, using simulations based on a mechanoelastic model applied to 2D triangular lattices composed of molecules linked by springs and embedded in a surfactant. We consider two Gaussian distributions: one of the size of the nanoparticles and one of the elastic interactions between edge spin-crossover molecules and the surfactant molecules. In order to disentangle the kinetic and non-kinetic...
AN Lyn: a multiperiodic Delta Scuti star showing atypical light curves
NASA Astrophysics Data System (ADS)
Rodriguez, E.; Gonzalez-Bedolla, S. F.; Rolland, A.; Costa, V.; Lopez-Gonzalez, M. J.; Lopez de Coca, P.
1997-07-01
We have collected simultaneous uvby photometry of the Delta Sct star AN Lyn during the years 1995 and 1996 at the observatories of San Pedro Mertir, Mexico and Sierra Nevada, Spain. Firstly, analysis of frequencies of our 1995's data set was carried out using the Discrete Fourier Transform method, as described in Lopez de Coca et al. (1984), to the filter v. The periodograms showed a principal peak at v1 ~ 10.1756 c/d, very close to that frequency which corresponds to the period P ~0.0982739 d derived from earlier works. After prewhitening for v1 we found a second peak at 20.3525 c/d that corresponds to 2*v1. When these two frequencies are subtracted from the light curves, the periodograms show some peaks that reveal that additional frequencies are remaining in the spectra at very low amplitude as compared with the amplitude of the main peak (less than 5%).
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
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
NASA Astrophysics Data System (ADS)
Erber, T.; Guralnick, S. A.; Michels, S. C.
1993-06-01
Fatigue in materials is the result of cumulative damage processes that are usually induced be repeated loading cycles. Since the energy dissipation associated with damage is irreversible, and the loading cycles are accompanied by the evolution of heat, the corresponding relation between stress and strain is not single-valued; but rather exhibits a memory dependence, or hysteresis. Conversely, sustained hysteresis is a necessary condition for fatigue and is related to the rate of damage accumulation. Engineering design and safety standards for estimating fatigue life are based in part on the Manson-Coffin relations between the width of stress-strain hysteresis loops and the number of loading cycles required to produce failure in test pieces. Experimental and theoretical results show that this relation can be extended into a simple phenomenological description of fatigue that directly links total hysteresis energy dissipation, the cumulation of material damage, and the average number of loading cycles leading to failure. Detailed features of the hysteresis can be understood with the help of analogies between the incremental collapse of structures and the inception and organization of damage in materials. In particular, scanning tunneling microscope measurements of the threshold of mechanical irreversibility and acoustic emission patterns may be used to check on the evolution of hysteresis at the microscopic level.
NASA Astrophysics Data System (ADS)
Nobuhiko Sakai,; Ritthikrai Chai-Ngam,; Akihisa Koizumi,; Hisao Kobayashi,
2010-06-01
The spacer thickness dependence of the interlayer magnetic coupling (IMC) between Gd and Fe layers separated by Al spacers has been studied. Magnetization measurement and X-ray magnetic circular dicroism (XMCD) spectroscopy at the Gd-L3 edge have been carried out on sputtered Fe (20 Å)/Al (R Å)/Gd (40 Å) multilayer films (MLFs) for R = 0, 5, 10, and 100 and on some reference films. Experimental data at low magnetic fields below 1 kOe are carefully investigated. A simple theoretical model is introduced to evaluate the strength of IMC. The energy of IMC is represented by the term J MFe \\cdot MGd, in which MFe and MGd denote the average overall magnetic moments of Fe and Gd layers, respectively. It is found that J, which is evaluated from the magnetization curves and the Gd-XMCD signals, is 370 × 104 Oe\\cdotcm2/emu for MLF of R = 0, and can be reduced by one order of magnitude when R is changed from 0 to 10. Most of characteristic features of the experimental data are ascribed to the varing magnetization of Gd layers. It is found that 40 Å Gd layers, which are paramagnetic at 5 K when isolated using 100 Å Al spacers, show magnetic hysteresis when sandwiched between Fe layers.
NASA Astrophysics Data System (ADS)
Sódor, Á.; Chené, A.-N.; De Cat, P.; Bognár, Zs.; Wright, D. J.; Marois, C.; Walker, G. A. H.; Matthews, J. M.; Kallinger, T.; Rowe, J. F.; Kuschnig, R.; Guenther, D. B.; Moffat, A. F. J.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W.
2014-08-01
Context. The central star of the HR 8799 system is a ? Doradus-type pulsator. The system harbours four planetary-mass companions detected by direct imaging, and is a good solar system analogue. The masses of the companions are not accurately known because the estimation depends greatly on the age of the system, which is also not known with sufficient accuracy. Asteroseismic studies of the star might help to better constrain the age of HR 8799. We organized an extensive photometric and multi-site spectroscopic observing campaign to study the pulsations of the central star. Aims: The aim of the present study is to investigate the pulsation properties of HR 8799 in detail via the ultra-precise 47 d nearly continuous photometry obtained with the Microvariability and Oscillations in STars (MOST) space telescope, and to find as many independent pulsation modes as possible, which is the prerequisite for an asteroseismic age determination. Methods: We carried out Fourier analysis of the wide-band photometric time series. Results: We find that resonance and sudden amplitude changes characterize the pulsation of HR 8799. The dominant frequency is always at f1 = 1.978 d-1.Many multiples of one-ninth of the dominant frequency appear in the Fourier spectrum of the MOST data: n/9 f1, where n = {1,2,3,4,5,6,7,8,9,10,13,14,17,18}. Our analysis also reveals that many of these peaks show strong amplitude decrease and phase variations even on the 47 d time scale. The dependencies between the pulsation frequencies of HR 8799 make the planned subsequent asteroseismic analysis rather difficult. We point out some resemblance between the light curve of HR 8799 and the modulated pulsation light curves of Blazhko RR Lyrae stars. Based on data from the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute for Aerospace Studies and the University of British Columbia, with the assistance of the University of Vienna.
NASA Technical Reports Server (NTRS)
Flatley, Thomas W.; Henretty, Debra A.
1995-01-01
The Passive Aerodynamically Stabilized Magnetically Damped Satellite (PAMS) will be deployed from the Space Shuttle and used as a target for a Shuttle-mounted laser. It will be a cylindrical satellite with several corner cube reflectors on the ends. The center of mass of the cylinder will be near one end, and aerodynamic torques will tend to align the axis of the cylinder with the spacecraft velocity vector. Magnetic hysteresis rods will be used to provide passive despin and oscillation-damping torques on the cylinder. The behavior of the hysteresis rods depends critically on the 'B/H' curves for the combination of materials and rod length-to-diameter ratio ('l-over-d'). These curves are qualitatively described in most Physics textbooks in terms of major and minor 'hysteresis loops'. Mathematical modeling of the functional relationship between B and H is very difficult. In this paper, the physics involved is not addressed, but an algorithm is developed which provides a close approximation to empirically determined data with a few simple equations suitable for use in computer simulations.
Mathematical models of hysteresis
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.
Tokunaga, Tetsu K.; Olson, Keith R.; Wan, Jiamin
2004-03-12
Hysteresis in the relation between water saturation and matric potential is generally regarded as a basic aspect of unsaturated porous media. However, the nature of an upper length scale limit for saturation hysteresis has not been previously addressed. Since hysteresis depends on whether or not capillary rise occurs at the grain scale, this criterion was used to predict required combinations of grain size, surface tension, fluid-fluid density differences, and acceleration in monodisperse systems. The Haines number (Ha), composed of the aforementioned variables, is proposed as a dimensionless number useful for separating hysteretic (Ha < 15) versus nonhysteretic (Ha > 15) behavior. Vanishing of hysteresis was predicted to occur for grain sizes greater than 10.4 +- 0.5 mm, for water-air systems under the acceleration of ordinary gravity, based on Miller-Miller scaling and Haines' original model for hysteresis. Disappearance of hysteresis was tested through measurements of drainage and wetting curves of sands and gravels and occurs between grain sizes of 10 and 14 mm (standard conditions). The influence of surface tension was tested through measurements of moisture retention in 7 mm gravel, without and with a surfactant (sodium dodecylbenzenesulfonate (SDBS)). The ordinary water system (Ha = 7) exhibited hysteresis, while the SDBS system (Ha = 18) did not. The experiments completed in this study indicate that hysteresis in moisture retention relations has an upper limit at Ha = 16 +- 2 and show that hysteresis is not a fundamental feature of unsaturated porous media.
Origin of hysteresis in resistive switching in magnetite is Joule heating
NASA Astrophysics Data System (ADS)
Fursina, A. A.; Sofin, R. G. S.; Shvets, I. V.; Natelson, D.
2009-06-01
In many transition-metal oxides the electrical resistance is observed to undergo dramatic changes induced by large biases. In magnetite, Fe3O4 , below the Verwey temperature, an electric-field-driven transition to a state of lower resistance was recently found, with hysteretic current-voltage response. We report the results of pulsed electrical conduction measurements in epitaxial magnetite thin films. We show that while the high- to low-resistance transition is driven by electric field, the hysteresis observed in I-V curves results from Joule heating in the low-resistance state. The shape of the hysteresis loop depends on pulse parameters and reduces to a hysteresis-free “jump” of the current provided thermal relaxation is rapid compared to the time between voltage pulses. A simple relaxation-time thermal model is proposed that captures the essentials of the hysteresis mechanism.
90 3. RIEMANNIAN MANIFOLDS (d) Show that the curves #, # : R # G given in these coordinates
Godinho, Leonor
) infinitely many geodesics; (ii) no geodesics. (h) Show that no open set U # G is isometric to an open set V a unique geodesic c v : I # M defined on a maximal open interval I # R such that 0 # I, c v (0) = p and â?? c OF GEODESICS 91 and consequently # â?? # â?? # = # a â?? cv (a â?? c v ) = a 2 # â?? cv â?? c v = 0. Therefore # is also
Zheng, Han; Wang, Qiufeng; Zhu, Xianjin; Li, Yingnian; Yu, Guirui
2014-01-01
Evapotranspiration (ET) is an important component of the water cycle in terrestrial ecosystems. Understanding the ways in which ET changes with meteorological factors is central to a better understanding of ecological and hydrological processes. In this study, we used eddy covariance measurements of ET from a typical alpine shrubland meadow ecosystem in China to investigate the hysteresis response of ET to environmental variables including air temperature (Ta), vapor pressure deficit (VPD) and net radiation (Rn) at a diel timescale. Meanwhile, the simulated ET by Priestly-Taylor equation was used to interpret the measured ET under well-watered conditions. Pronounced hysteresis was observed in both Ta and VPD response curves of ET. At a similar Ta and VPD, ET was always significantly depressed in the afternoon compared with the morning. But the hysteresis response of ET to Rn was not evident. Similar hysteresis patterns were also observed in the Ta/VPD response curves of simulated ET. The magnitudes of the measured and simulated hysteresis loops showed similar seasonal variation, with relatively smaller values occurring from May to September, which agreed well with the lifetime of plants and the period of rainy season at this site. About 62% and 23% of changes in the strength of measured ET-Ta and ET-VPD loops could be explained by the changes in the strength of simulated loops, respectively. Thus, the time lag between Rn and Ta/VPD is the most important factor generating and modulating the ET-Ta/VPD hysteresis, but plants and water status also contribute to the hysteresis response of ET. Our research confirmed the different hysteresis in the responses of ET to meteorological factors and proved the vital role of Rn in driving the diel course of ET. PMID:24896829
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.
Hysteresis and feedback of ice sheet response
NASA Astrophysics Data System (ADS)
Abe-Ouchi, A.; Saito, F.; Takahashi, K.
2014-12-01
Investigating the response of ice sheets to climatic forcings in the past by climate-ice sheet modelling is important for understanding the ice sheets' change. The 100-kyr cycle of the large Northern Hemisphere ice sheets and fast termination of the glacial cycle are the prominent pattern known from paleoclimate records. We simulate the past glacial cycles with an ice sheet model, IcIES in combination with a general circulation model, MIROC, using the time series of insolation and atmospheric CO2. Feedback processes between ice sheet and atmosphere such as the ice albedo feedback, the elevation-mass balance feedback, desertification effect and stationary wave feedback are analyzed. We show that the threshold of termination of the glacial cycles can be explained by the pattern of the hysteresis of ice sheet change, i.e. multiple steady states of the ice sheets under climatic forcings. We find that slope of the upper branch of the multiple equilibria curve for Laurentide ice volumes is fundamental for the observed glacial patterns. Finally, we discuss the similarity and difference between the hysteresis structure of ice sheets variation for Northern Hemisphere ice sheets, Antarctica and Greenland.
Hysteresis in a quantized superfluid `atomtronic' circuit
NASA Astrophysics Data System (ADS)
Eckel, Stephen; Lee, Jeffrey G.; Jendrzejewski, Fred; Murray, Noel; Clark, Charles W.; Lobb, Christopher J.; Phillips, William D.; Edwards, Mark; Campbell, Gretchen K.
2014-02-01
Atomtronics is an emerging interdisciplinary field that seeks to develop new functional methods by creating devices and circuits where ultracold atoms, often superfluids, have a role analogous to that of electrons in electronics. Hysteresis is widely used in electronic circuits--it is routinely observed in superconducting circuits and is essential in radio-frequency superconducting quantum interference devices. Furthermore, it is as fundamental to superfluidity (and superconductivity) as quantized persistent currents, critical velocity and Josephson effects. Nevertheless, despite multiple theoretical predictions, hysteresis has not been previously observed in any superfluid, atomic-gas Bose-Einstein condensate. Here we directly detect hysteresis between quantized circulation states in an atomtronic circuit formed from a ring of superfluid Bose-Einstein condensate obstructed by a rotating weak link (a region of low atomic density). This contrasts with previous experiments on superfluid liquid helium where hysteresis was observed directly in systems in which the quantization of flow could not be observed, and indirectly in systems that showed quantized flow. Our techniques allow us to tune the size of the hysteresis loop and to consider the fundamental excitations that accompany hysteresis. The results suggest that the relevant excitations involved in hysteresis are vortices, and indicate that dissipation has an important role in the dynamics. Controlled hysteresis in atomtronic circuits may prove to be a crucial feature for the development of practical devices, just as it has in electronic circuits such as memories, digital noise filters (for example Schmitt triggers) and magnetometers (for example superconducting quantum interference devices).
Stix, Jakob
Birational Galois sections over Q, families of elliptic curves and modularity JAKOB STIX Abstract -- We show that birational liftable Galois sections of a smooth hyperbolic curve X/Q come from a Q-rational point if and only if a certain 2-dimensional Galois representation obtained from a family of elliptic
Hysteresis of magnetostructural transitions: Repeatable and non-repeatable processes
NASA Astrophysics Data System (ADS)
Provenzano, Virgil; Della Torre, Edward; Bennett, Lawrence H.; ElBidweihy, Hatem
2014-02-01
The Gd5Ge2Si2 alloy and the off-stoichiometric Ni50Mn35In15 Heusler alloy belong to a special class of metallic materials that exhibit first-order magnetostructural transitions near room temperature. The magnetic properties of this class of materials have been extensively studied due to their interesting magnetic behavior and their potential for a number of technological applications such as refrigerants for near-room-temperature magnetic refrigeration. The thermally driven first-order transitions in these materials can be field-induced in the reverse order by applying a strong enough field. The field-induced transitions are typically accompanied by the presence of large magnetic hysteresis, the characteristics of which are a complicated function of temperature, field, and magneto-thermal history. In this study we show that the virgin curve, the major loop, and sequentially measured MH loops are the results of both repeatable and non-repeatable processes, in which the starting magnetostructural state, prior to the cycling of field, plays a major role. Using the Gd5Ge2Si2 and Ni50Mn35In15 alloys, as model materials, we show that a starting single phase state results in fully repeatable processes and large magnetic hysteresis, whereas a mixed phase starting state results in non-repeatable processes and smaller hysteresis.
Corneal hysteresis and its relevance to glaucoma
Deol, Madhvi; Taylor, David A.; Radcliffe, Nathan M.
2015-01-01
Purpose of review Glaucoma is a leading cause of irreversible blindness worldwide. It is estimated that roughly 60.5 million people had glaucoma in 2010 and that this number is increasing. Many patients continue to lose vision despite apparent disease control according to traditional risk factors. The purpose of this review is to discuss the recent findings with regard to corneal hysteresis, a variable that is thought to be associated with the risk and progression of glaucoma. Recent findings Low corneal hysteresis is associated with optic nerve and visual field damage in glaucoma and the risk of structural and functional glaucoma progression. In addition, hysteresis may enhance intraocular pressure (IOP) interpretation: low corneal hysteresis is associated with a larger magnitude of IOP reduction following various glaucoma therapies. Corneal hysteresis is dynamic and may increase in eyes after IOP-lowering interventions are implemented. Summary It is widely accepted that central corneal thickness is a predictive factor for the risk of glaucoma progression. Recent evidence shows that corneal hysteresis also provides valuable information for several aspects of glaucoma management. In fact, corneal hysteresis may be more strongly associated with glaucoma presence, risk of progression, and effectiveness of glaucoma treatments than central corneal thickness. PMID:25611166
Preisach modeling of magnetostrictive hysteresis
Adly, A.A.; Mayergoyz, I.D. ); Bergqvist, A. )
1991-04-15
Preisach-type models are suggested for the description of strain hysteresis of magnetostrictive materials. It is pointed out that the strain hysteresis has some peculiar properties in comparison with magnetic hysteresis. These peculiarities of strain hysteresis are discussed in detail along with the identification problem for these models.
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...
Transport, hysteresis and avalanches in artificial spin ice systems
Reichhardt, Charles; Reichhardt, Cynthia J; Libal, A
2010-01-01
We examine the hopping dynamics of an artificial spin ice system constructed from colloids on a kagome optical trap array where each trap has two possible states. By applying an external drive from an electric field which is analogous to a biasing applied magnetic field for real spin systems, we can create polarized states that obey the spin-ice rules of two spins in and one spin out at each vertex. We demonstrate that when we sweep the external drive and measure the fraction of the system that has been polarized, we can generate a hysteresis loop analogous to the hysteretic magnetization versus external magnetic field curves for real spin systems. The disorder in our system can be readily controlled by changing the barrier that must be overcome before a colloid can hop from one side of a trap to the other. For systems with no disorder, the effective spins all flip simultaneously as the biasing field is changed, while for strong disorder the hysteresis curves show a series of discontinuous jumps or avalanches similar to Barkhausen noise.
The hysteresis behavior of an Ising nanowire with core/shell morphology: Monte Carlo treatment
NASA Astrophysics Data System (ADS)
Boughazi, B.; Boughrara, M.; Kerouad, M.
2014-08-01
We have used Monte Carlo Simulations (MCS) to study the hysteresis behavior of the magnetic nanowire with core/shell morphology described by the spin {1}/{2} Ising particles in the core and the spin {3}/{2} Ising particles in the surface shell. The hysteresis curves are obtained for different temperatures. We find that the hysteresis loop areas decrease when the temperature increases and the hysteresis loops disappear at certain temperatures. Barkhausen jumps are observed for the ferromagnetic nanowire system. An unusual form of triple hysteresis behaviors is observed for the ferrimagnetic nanowire system. The thermal behaviors of the coercivity and the remanent magnetization are also investigated.
Role of reversible susceptibility in ferromagnetic hysteresis
NASA Astrophysics Data System (ADS)
Schneider, Carl S.
2002-05-01
An equation of state based upon saturation magnetization, Ms, coercive field, Hc, and the reversible susceptibility function of magnetization is proposed for ferromagnetic hysteresis. Reversible susceptibility divided by the initial susceptibility is the anisotropy function of magnetization, ?r, ranging from one in the demagnetized state to zero at saturation, and varying with magnetic history. Its dependence on scaled magnetization, m=M/Ms on the interval (-1,1) varies with material, allowing characterization of anisotropy classes. Precise measurements have been made of reversible susceptibility, initial and saturate magnetization curves, and loops for Orthonol™, annealed 3% nickel steel and as-received 1018 steel, representing crystals, isotropic polycrystals and composite ferromagnets, respectively. Magnetization change is the product of the reversible susceptibility, change in the applied field and the cooperative function due to domain interactions. This function is 1+?m for the virgin curve with half this slope from any reversal, where ?=Ms/XiHc is the hysteresis coefficient. Variation of ? for 1018 steel is due to distributed coercivities, and causes sigmoid B(H) curves. In the scaled field representation, where h=H/Hc, the cooperative function is 1/(1-h?r), a hyperbolic field dependence smeared by the anisotropy function. Constant anisotropy causes closed hysteresis loops, while variable anisotropy causes creeping of cycled asymmetric loops. In ferromagnetism, 1/?=1/?r-h, normal scaled reluctivity is reduced from its reversible value by the scaled field.
Contact angle hysteresis, adhesion, and marine biofouling.
Schmidt, Donald L; Brady, Robert F; Lam, Karen; Schmidt, Dale C; Chaudhury, Manoj K
2004-03-30
Adhesive and marine biofouling release properties of coatings containing surface-oriented perfluoroalkyl groups were investigated. These coatings were prepared by cross-linking a copolymer of 1H,1H,2H,2H-heptadecafluorodecyl acrylate and acrylic acid with a copolymer of poly(2-isopropenyl-2-oxazoline) and methyl methacrylate at different molar ratios. The relationships between contact angle, contact angle hysteresis, adhesion, and marine biofouling were studied. Adhesion was determined by peel tests using pressure-sensitive adhesives. The chemical nature of the surfaces was studied by using X-ray photoelectron spectroscopy. Resistance to marine biofouling of an optimized coating was studied by immersion in seawater and compared to previous, less optimized coatings. The adhesive release properties of the coatings did not correlate well with the surface energies of the coatings estimated from the static and advancing contact angles nor with the amount of fluorine present on the surface. The adhesive properties of the surfaces, however, show a correlation with water receding contact angles and contact angle hysteresis (or wetting hysteresis) resulting from surface penetration and surface reconstruction. Coatings having the best release properties had both the highest cross-link density and the lowest contact angle hysteresis. An optimized coating exhibited unprecedented resistance to marine biofouling. Water contact angle hysteresis appears to correlate with marine biofouling resistance. PMID:15835160
Mesoscopic magnetomechanical hysteresis in a magnetorheological elastomer
NASA Astrophysics Data System (ADS)
Biller, A. M.; Stolbov, O. V.; Raikher, Yu. L.
2015-08-01
Field-induced magnetostatic interaction in a pair of identical particles made of a magnetically soft ferromagnet is studied. It is shown that due to saturation of the ferromagnet magnetization, this case differs significantly from the (super)paramagnetic one. A numerical solution is given, discussed, and compared with that provided by a simpler model (nonlinear mutual dipoles). We show that for multidomain ferromagnetic particles embedded in an elastomer matrix, as for paramagnetic ones in the same environment, pair clusters may form or break by a hysteresis scenario. However, the magnetization saturation brings in important features to this effect. First, the bistability state and the hysteresis take place only in a limited region of the material parameters of the system. Second, along with the hysteresis jumps occurring under the sole influence of the field, the "latent" hysteresis is possible which realizes only if the action of the field is combined with some additional (nonmagnetic) external factor. The obtained conditions, when used to assess the possibility of clustering in real magnetorheological polymers, infer an important role of mesoscopic magnetomechanical hysteresis for the macroscopic properties of these composites.
Hysteresis and multi-state behavior of counterflow flame in a blowing cylindrical burner
NASA Astrophysics Data System (ADS)
Chai, Hsing-Sheng
2009-09-01
This study focuses on flame hysteresis over a porous cylindrical burner. The hysteresis results from different operation procedure of the experiment. Gradually increasing inflow velocity can transform the envelope flame into a wake flame. The blow-off curve can be plotted by determining every critical inflow velocity that makes an envelope flame become a wake flame at different fuel-ejection velocities. In contrast, decreasing the inflow velocity can transform the wake or lift-off flame into an envelope one. The reattachment curve can be obtained by the same method to explore the blow-off curve, but the intake process is reverse. However, these two curves are not coincident, except the origin. The discrepancy between them is termed as hysteresis, and it results from the difference between the burning velocities associated with both curves. At the lowest fuel-ejection velocity, no hysteresis exists between both curves owing to nearly no burning velocity difference there. Then, raising the fuel-ejection velocity enhances hysteresis and the discrepancy between the two curves. However, as fuel-ejection velocity exceeds a critical value, the intensity of hysteresis almost keeps constant and causes the two curves to be parallel to each other.
Dynamic hysteresis features in a two-dimensional mixed Ising system
NASA Astrophysics Data System (ADS)
Erta?, Mehmet; Keskin, Mustafa
2015-08-01
The dynamic hysteresis features in a two-dimensional mixed spin (1 , 3 / 2) Ising system are studied by using the within the effective-field theory with correlations based on Glauber-type stochastic. The dynamic phase transition temperatures and dynamic hysteresis curves are obtained for both the ferromagnetic and antiferromagnetic interactions. It is observed that the dynamic hysteresis loop areas increase when the reduced temperatures increase, and the dynamic hysteresis loops disappear at certain reduced temperatures. The thermal behaviors of the coercivity and remanent magnetizations are also investigated. The results are compared with some theoretical and experimental works and found in a qualitatively good agreement.
Stiffness and hysteresis properties of some prosthetic feet.
van Jaarsveld, H W; Grootenboer, H J; de Vries, J; Koopman, H F
1990-12-01
A prosthetic foot is an important element of a prosthesis, although it is not always fully recognized that the properties of the foot, along with the prosthetic knee joint and the socket, are in part responsible for the stability and metabolic energy cost during walking. The stiffness and the hysteresis, which are the topics of this paper, are not properly prescribed, but could be adapted to improve the prosthetic walking performance. The shape is strongly related to the cosmetic appearance and so can not be altered to effect these improvements. Because detailed comparable data on foot stiffness and hysteresis, which are necessary to quantify the differences between different types of feet, are absent in literature, these properties were measured by the authors in a laboratory setup for nine different prosthetic feet, bare and with two different shoes. One test cycle consisted of measurements of load deformation curves in 66 positions, representing the range from heel strike to toe-off. The hysteresis is defined by the energy loss as a part of the total deformation energy. Without shoes significant differences in hysteresis between the feet exist, while with sport shoes the differences in hysteresis between the feet vanish for the most part. Applying a leather shoe leads to an increase of hysteresis loss for all tested feet. The stiffness turned out to be non-constant, so mean stiffness is used.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2095529
Conductance hysteresis in the voltage-dependent anion channel.
Rappaport, Shay M; Teijido, Oscar; Hoogerheide, David P; Rostovtseva, Tatiana K; Berezhkovskii, Alexander M; Bezrukov, Sergey M
2015-09-01
Hysteresis in the conductance of voltage-sensitive ion channels is observed when the transmembrane voltage is periodically varied with time. Although this phenomenon has been used in studies of gating of the voltage-dependent anion channel, VDAC, from the outer mitochondrial membrane for nearly four decades, full hysteresis curves have never been reported, because the focus was solely on the channel opening branches of the hysteresis loops. We studied the hysteretic response of a multichannel VDAC system to a triangular voltage ramp the frequency of which was varied over three orders of magnitude, from 0.5 mHz to 0.2 Hz. We found that in this wide frequency range the area encircled by the hysteresis curves changes by less than a factor of three, suggesting broad distribution of the characteristic times and strongly non-equilibrium behavior. At the same time, quasi-equilibrium two-state behavior is observed for hysteresis branches corresponding to VDAC opening. This enables calculation of the usual equilibrium gating parameters, gating charge and voltage of equipartitioning, which were found to be almost insensitive to the ramp frequency. To rationalize this peculiarity, we hypothesize that during voltage-induced closure and opening the system explores different regions of the complex free energy landscape, and, in the opening branch, follows quasi-equilibrium paths. PMID:26094068
Ac magnetorestriction hysteresis and magnetization direction in grain oriented silicon steels
Mogi, Hisashi; Matsuo, Yukio; Kumano, Tomoji
1999-09-01
A hysteresis curve of ac magnetostriction was measured, magnetizing a grain oriented silicon steel in the direction deviated from rolling direction of a sample. The ac magnetostriction ({lambda} ac) curves were analyzed as harmonics in the interest of noise spectrum of such as a power transformer. The domain structure model in this magnetostriction process was proposed. The hysteresis was large in the magnetization direction inclined at 30 and 90{degree} from the rolling direction.
Macroscopic theory for capillary-pressure hysteresis.
Athukorallage, Bhagya; Aulisa, Eugenio; Iyer, Ram; Zhang, Larry
2015-03-01
In this article, we present a theory of macroscopic contact angle hysteresis by considering the minimization of the Helmholtz free energy of a solid-liquid-gas system over a convex set, subject to a constant volume constraint. The liquid and solid surfaces in contact are assumed to adhere weakly to each other, causing the interfacial energy to be set-valued. A simple calculus of variations argument for the minimization of the Helmholtz energy leads to the Young-Laplace equation for the drop surface in contact with the gas and a variational inequality that yields contact angle hysteresis for advancing/receding flow. We also show that the Young-Laplace equation with a Dirichlet boundary condition together with the variational inequality yields a basic hysteresis operator that describes the relationship between capillary pressure and volume. We validate the theory using results from the experiment for a sessile macroscopic drop. Although the capillary effect is a complex phenomenon even for a droplet as various points along the contact line might be pinned, the capillary pressure and volume of the drop are scalar variables that encapsulate the global quasistatic energy information for the entire droplet. Studying the capillary pressure versus volume relationship greatly simplifies the understanding and modeling of the phenomenon just as scalar magnetic hysteresis graphs greatly aided the modeling of devices with magnetic materials. PMID:25646688
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.
Eliminating hysteresis of piezoelectric deformable mirror by charge control
NASA Astrophysics Data System (ADS)
Ma, Jianqiang; Chen, Junjie; Hu, Yanlei; Tian, Lei; Li, Baoqing; Chu, Jiaru
2015-08-01
Inherent hysteresis of piezoelectric deformable mirror (DM) limits the performance of adaptive optics (AO) systems including bandwidth and residual wavefront error. A charge control method based on switched capacitor charge pump was proposed to eliminate the hysteresis of piezoelectric DM. Experimental results show that the hysteresis of a unimorph DM was reduced from 11% to less than 1%. It indicates that the proposed charge control method has the potential to improve the deformation precision for one step correction as well as the bandwidth of the AO systems.
High contact angle hysteresis of superhydrophobic surfaces: Hydrophobic defects
NASA Astrophysics Data System (ADS)
Chang, Feng-Ming; Hong, Siang-Jie; Sheng, Yu-Jane; Tsao, Heng-Kwong
2009-08-01
A typical superhydrophobic surface is essentially nonadhesive and exhibits very low water contact angle (CA) hysteresis, so-called Lotus effect. However, leaves of some plants such as scallion and garlic with an advancing angle exceeding 150° show very serious CA hysteresis. Although surface roughness and epicuticular wax can explain the very high advancing CA, our analysis indicates that the unusual hydrophobic defect, diallyl disulfide, is the key element responsible for contact line pinning on allium leaves. After smearing diallyl disulfide on an extended polytetrafluoroethylene (PTFE) film, which is originally absent of CA hysteresis, the surface remains superhydrophobic but becomes highly adhesive.
2015-01-01
Summary In isolated bimetallic nanoscale systems the limit amount of matter and surface-induced size effects can change the thermodynamics of first-order phase transformation. In this paper we present theoretical modification of Gibbs free energy concept describing first-order phase transformation of binary alloyed nanoparticles taking into account size effects as well as depletion and hysteresis effects. In such a way the hysteresis in a form of nonsymmetry for forth and back transforming paths takes place; compositional splitting and the loops-like splitted path on the size dependent temperature–composition phase diagram occur. Our calculations for individual Cu–Ni nanoparticle show that one must differentiate the solubility curves and the equilibrium loops (discussed here in term of solidification and melting loops). For the first time we have calculated and present here on the temperature–composition phase diagram the nanomelting loop at the size of 80 nm and the nanosolidification loop at the size of 25 nm for an individual Cu–Ni nanoparticle. So we observe the difference between the size-dependent phase diagram and solubility diagram, between two-phase equilibrium curves and solubility curves; also intersection of nanoliquidus and nanosolidus is available. These findings lead to the necessity to reconsider such basic concepts in materials science as phase diagram and solubility diagram.
Hysteresis modeling in ballistic carbon nanotube field-effect transistors.
Liu, Yian; Moura, Mateus S; Costa, Ademir J; de Almeida, Luiz Alberto L; Paranjape, Makarand; Fontana, Marcio
2014-01-01
Theoretical models are adapted to describe the hysteresis effects seen in the electrical characteristics of carbon nanotube field-effect transistors. The ballistic transport model describes the contributions of conduction energy sub-bands over carbon nanotube field-effect transistor drain current as a function of drain-source and gate-source voltages as well as other physical parameters of the device. The limiting-loop proximity model, originally developed to understand magnetic hysteresis, is also utilized in this work. The curves obtained from our developed model corroborate well with the experimentally derived hysteretic behavior of the transistors. Modeling the hysteresis behavior will enable designers to reliably use these effects in both analog and memory applications. PMID:25187698
Orientational hysteresis in swarms of active particles in external field
Romensky, Maksym
2015-01-01
Structure and ordering in swarms of active particles have much in common with condensed matter systems like magnets or liquid crystals. A number of important characteristics of such materials can be obtained via dynamic tests such as hysteresis. In this work, we show that dynamic hysteresis can be observed also in swarms of active particles and possesses similar properties to the counterparts in magnetic materials. To study the swarm dynamics, we use computer simulation of the active Brownian particle model with dissipative interactions. The swarm is confined to a narrow linear channel and one-dimensional polar order parameter is measured. In an oscillating external field, the order parameter demonstrates dynamic hysteresis with the shape of the loop and its area varying with the amplitude and frequency of the applied field, swarm density and the noise intensity. We measure the scaling exponents for the hysteresis loop area, which can be associated with the controllability of the swarm. Although the exponents...
Dynamic hysteresis in the rheology of complex fluids
NASA Astrophysics Data System (ADS)
Puisto, Antti; Mohtaschemi, Mikael; Alava, Mikko J.; Illa, Xavier
2015-04-01
Recently, rheological hysteresis has been studied systematically in a wide range of complex fluids combining global rheology and time-resolved velocimetry. In this paper we present an analysis of the roles of the three most fundamental mechanisms in simple-yield-stress fluids: structure dynamics, viscoelastic response, and spatial flow heterogeneities, i.e., time-dependent shear bands. Dynamical hysteresis simulations are done analogously to rheological ramp-up and -down experiments on a coupled model which incorporates viscoelasticity and time-dependent structure evolution. Based on experimental data, a coupling between hysteresis measured from the local velocity profiles and that measured from the global flow curve has been suggested. According to the present model, even if transient shear banding appears during the shear ramps, in typical narrow-gap devices, only a small part of the hysteretic response can be attributed to heterogeneous flow. This results in decoupling of the hysteresis measured from the local velocity profiles and the global flow curve, demonstrating that for an arbitrary time-dependent rheological response this proposed coupling can be very weak.
Hysteresis in Analytical Solutions for Three-phase Flow
NASA Astrophysics Data System (ADS)
Lambers, J. V.; LaForce, T.
2011-12-01
Hysteresis in relative permeability is a widely-recognized phenomenon that impacts oil recovery in water and gas (WAG) injection. Several authors (1-3) have constructed analytical solutions for two-phase oil/water or gas/water flow in enhanced oil recovery however, analytical solutions have not previously been constructed for the three-phase flow problem for immiscible water, oil and gas including hysteresis. In this work analytical solutions are constructed for water and gas floods in a previously water-flooded oil reservoir with and without hysteresis. A simplified model is used in the analysis that qualitatively captures the behavior of oil-phase hysteresis for repeated water imbibition and drainage cycles. Many of the displacements considered have a reversal of flow direction within the displacement, requiring a matching condition to be enforced between the imbibition and drainage relative permeability curves at the point of flow reversal. A suitable matching criterion for the hysteretic curves is presented. A single water/gas injection mixture is considered, with varying initial oil and water volumes present in the reservoir. When hysteresis occurs in a displacement the entire saturation path depends on the initial volumes of oil and water present at the onset of WAG flooding. When hysteresis is ignored most of the displacement is identical for a large range of initial oil and water mixtures, with only the velocity of the leading shock changing. For the displacements which only encounter drainage of the water phase, solutions with and without hysteresis are identical. 1) K. M. Furati, ``Effects of Relative Permeability History Dependence on Two-Phase Flow in Porous Media,'' Transport in Porous Media 28: 181-203, 1997. 2) B. Plohr, D. Marchesin, P. Bedrikovetsky and P. Krause, ``Modeling hysteresis in porous media flow via relaxation,'' Computational Geosciences 5: 225-256, 2001. 3) F. M. Van Kats and C. J. Van Duijn, ``A Mathematical Model for Hysteretic Two-Phase Flow in Porous Media,'' Transport in Porous Media 43: 239-263, 2001.
Hysteresis Characterization Using Charge-Feedback Control for a LIPCA Device
Mossi, Karla
study the no-load behavior of a lightweight piezo-composite curved actuator (LIPCA) subjected to voltage and charge control. First, we examine the effect of hysteresis and creep when the actuator is voltage-load displacement behavior of a lightweight piezo-composite curved actuator (LIPCA) . First, we examine the effect
Bukharov, A A; Ovchinnikov, A S; Baranov, N V; Inoue, K
2010-11-01
Using Monte Carlo simulations we investigate magnetic hysteresis in two- and three-dimensional systems of weakly antiferromagnetically coupled spin chains based on a scenario of domain wall (kink) motion within the chains. By adapting the model of walkers to simulate the domain wall dynamics and using the Ising-like dipole-dipole model, we study the effects of interchain coupling, temperature and anisotropy axis direction on hysteresis curves. PMID:21403338
Magnetic hysteresis of cerium doped bismuth ferrite thin films
NASA Astrophysics Data System (ADS)
Gupta, Surbhi; Tomar, Monika; Gupta, Vinay
2015-03-01
The influence of Cerium doping on the structural and magnetic properties of BiFeO3 thin films have been investigated. Rietveld refinement of X-ray diffraction data and successive de-convolution of Raman scattering spectra of Bi1-xCexFeO3 (BCFO) thin films with x=0-0.20 reflect the single phase rhombohedral (R3c) formation for x<0.08, whereas concentration-driven gradual structural phase transition from rhombohedral (R3c) to partial tetragonal (P4mm) phase follows for x?0.08. All low wavenumber Raman modes (<300 cm-1) showed a noticeable shift towards higher wavenumber with increase in doping concentration, except Raman E-1 mode (71 cm-1), shows a minor shift. Sudden evolution of Raman mode at 668 cm-1, manifested as A1-tetragonal mode, accompanied by the shift to higher wavenumber with increase in doping concentration (x) affirm partial structural phase transition. Anomalous wasp waist shaped (M-H) hysteresis curves with improved saturation magnetization (Ms) for BCFO thin films is attributed to antiferromagnetic interaction/hybridization between Ce 4f and Fe 3d electronic states. The contribution of both hard and soft phase to the total coercivity is calculated. Polycrystalline Bi0.88Ce0.12FeO3 thin film found to exhibit better magnetic properties with Ms=15.9 emu/g without any impure phase.
Anisotropic hysteresis on ratcheted superhydrophobic surfaces
H. Kusumaatmaja; J. M. Yeomans
2009-04-26
We consider the equilibrium behaviour and dynamics of liquid drops on a superhydrophobic surface patterned with sawtooth ridges or posts. Due to the anisotropic geometry of the surface patterning, the contact line can preferentially depin from one side of the ratchets, leading to a novel, partially suspended, superhydrophobic state. In both this configuration, and the collapsed state, the drops show strong directional contact angle hysteresis as they are pushed across the surface. The easy direction is, however, different for the two states. This observation allows us to interpret recent experiments describing the motion of water drops on butterfly wings.
Anisotropic hysteresis on ratcheted superhydrophobic surfaces
Kusumaatmaja, H
2009-01-01
We consider the equilibrium behaviour and dynamics of liquid drops on a superhydrophobic surface patterned with sawtooth ridges or posts. Due to the anisotropic geometry of the surface patterning, the contact line can preferentially depin from one side of the ratchets, leading to a novel, partially suspended, superhydrophobic state. In both this configuration, and the collapsed state, the drops show strong directional contact angle hysteresis as they are pushed across the surface. The easy direction is, however, different for the two states. This observation allows us to interpret recent experiments describing the motion of water drops on butterfly wings.
Phase Field Modeling of Hysteresis in Sessile Drops Srikanth Vedantam1,* and Mahesh V. Panchagnula2,
Panchagnula, Mahesh
the gradient energy and contact angle hysteresis from the kinetic coefficient. Using this theory, we discuss contact angle hysteresis on chemically heterogeneous surfaces. We show significant departure from-dimensional three-phase contact line (CL) kinetics and not the two- dimensional surface energy [1,8]. Owing
Orientational hysteresis in swarms of active particles in external field
Maksym Romensky; Vladimir Lobaskin
2015-05-28
Structure and ordering in swarms of active particles have much in common with condensed matter systems like magnets or liquid crystals. A number of important characteristics of such materials can be obtained via dynamic tests such as hysteresis. In this work, we show that dynamic hysteresis can be observed also in swarms of active particles and possesses similar properties to the counterparts in magnetic materials. To study the swarm dynamics, we use computer simulations of the active Brownian particle model with dissipative interactions. The swarm is confined to a narrow linear channel and the one-dimensional polar order parameter is measured. In an oscillating external field, the order parameter demonstrates dynamic hysteresis with the shape of the loop and its area varying with the amplitude and frequency of the applied field, swarm density and the noise intensity. We measure the scaling exponents for the hysteresis loop area, which can be associated with the controllability of the swarm. Although the exponents are non-universal and depend on the system's parameters, their limiting values can be predicted using a generic model of dynamic hysteresis. We also discuss similarities and differences between the swarm ordering dynamics and two-dimensional magnets.
Orientational hysteresis in swarms of active particles in external field
NASA Astrophysics Data System (ADS)
Romensky, M.; Lobaskin, V.
2015-07-01
Structure and ordering in swarms of active particles have much in common with condensed matter systems like magnets or liquid crystals. A number of important characteristics of such materials can be obtained via dynamic tests such as hysteresis. In this work, we show that dynamic hysteresis can be observed also in swarms of active particles and possesses similar properties to the counterparts in magnetic materials. To study the swarm dynamics, we use computer simulations of the active Brownian particle model with dissipative interactions. The swarm is confined to a narrow linear channel and the one-dimensional polar order parameter is measured. In an oscillating external field, the order parameter demonstrates dynamic hysteresis with the shape of the loop and its area varying with the amplitude and frequency of the applied field, swarm density and the noise intensity. We measure the scaling exponents for the hysteresis loop area, which can be associated with the controllability of the swarm. Although the exponents are non-universal and depend on the system's parameters, their limiting values can be predicted using a generic model of dynamic hysteresis. We also discuss similarities and differences between the swarm ordering dynamics and two-dimensional magnets.
NASA Astrophysics Data System (ADS)
Schwarz, Albert
2015-08-01
One says that a pair ( P, Q) of ordinary differential operators specify a quantum curve if . If a pair of difference operators ( K, L) obey the relation KL = q LK, where , we say that they specify a discrete quantum curve. This terminology is prompted by well known results about commuting differential and difference operators, relating pairs of such operators with pairs of meromorphic functions on algebraic curves obeying some conditions. The goal of this paper is to study the moduli spaces of quantum curves. We will relate the moduli spaces for different . We will show how to quantize a pair of commuting differential or difference operators (i.e., to construct the corresponding quantum curve or discrete quantum curve).
Modelling contact angle hysteresis on chemically patterned and superhydrophobic surfaces
H. Kusumaatmaja; J. M. Yeomans
2006-11-03
We investigate contact angle hysteresis on chemically patterned and superhydrophobic surfaces, as the drop volume is quasi-statically increased and decreased. We consider both two, and three, dimensions using analytical and numerical approaches to minimise the free energy of the drop. In two dimensions we find, in agreement with other authors, a slip, jump, stick motion of the contact line. In three dimensions this behaviour persists, but the position and magnitude of the contact line jumps are sensitive to the details of the surface patterning. In two dimensions we identify analytically the advancing and receding contact angles on the different surfaces and we use numerical insights to argue that these provide bounds for the three dimensional cases. We present explicit simulations to show that a simple average over the disorder is not sufficient to predict the details of the contact angle hysteresis, and to support an explanation for the low contact angle hysteresis of suspended drops on superhydrophobic surfaces.
Completely inverted hysteresis loops: Inhomogeneity effects or experimental artifacts
Song, C., E-mail: songcheng@mail.tsinghua.edu.cn; Cui, B.; Pan, F., E-mail: panf@mail.tsinghua.edu.cn [Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Yu, H. Y. [Center for Testing and Analyzing of Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)
2013-11-14
Completely inverted hysteresis loops (IHL) are obtained by the superconducting quantum interference device with large cooling fields (>10 kOe) in (La,Sr)MnO{sub 3} films with self-assembled LaSrMnO{sub 4}, an antiferromagnetic interface. Although the behaviours of measured loops show many features characteristic to the IHL, its origin, however, is not due to the exchange coupling between (La,Sr)MnO{sub 3}/LaSrMnO{sub 4}, an often accepted view on IHL. Instead, we demonstrate that the negative remanence arises from the hysteresis of superconducting coils, which drops abruptly when lower cooling fields are utilized. Hence the completely inverted hysteresis loops are experimental artifacts rather than previously proposed inhomogeneity effects in complicated materials.
Hysteresis and compensation behaviors of spin-3/2 cylindrical Ising nanotube system
Kocakaplan, Yusuf [Graduate School of Natural and Applied Sciences, Erciyes University, 38039 Kayseri (Turkey); Keskin, Mustafa, E-mail: keskin@erciyes.edu.tr [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)
2014-09-07
The hysteresis and compensation behaviors of the spin-3/2 cylindrical Ising nanotube system are studied within the framework of the effective-field theory with correlations. The effects of the Hamiltonian parameters are investigated on the magnetic and thermodynamic quantities, such as the total magnetization, hysteresis curves, and compensation behaviors of the system. Depending on the Hamiltonian parameters, some characteristic hysteresis behaviors are found, such as the existence of double and triple hysteresis loops. According to Néel classification nomenclature, the system displays Q-, R-, P-, N-, M-, and S- types of compensation behaviors for the appropriate values of the system parameters. We also compare our results with some recently published theoretical and experimental works and find a qualitatively good agreement.
Vector magnetic hysteresis of hard superconductors and C. Lopez2
MajÃ³s, Antonio BadÃa
Vector magnetic hysteresis of hard superconductors A. BadiÂ´a1 and C. LoÂ´pez2 1 Departamento de Fi for the magnetization vector of hard superconductors are investigated. The theory is based on the minimization of a cost functional C H(x) which weighs the changes of the magnetic-field vector within the sample. We show that Bean
Why Microtubules Run in Circles: Mechanical Hysteresis of the Tubulin Lattice
NASA Astrophysics Data System (ADS)
Ziebert, Falko; Mohrbach, Hervé; Kuli?, Igor M.
2015-04-01
The fate of every eukaryotic cell subtly relies on the exceptional mechanical properties of microtubules. Despite significant efforts, understanding their unusual mechanics remains elusive. One persistent, unresolved mystery is the formation of long-lived arcs and rings, e.g., in kinesin-driven gliding assays. To elucidate their physical origin we develop a model of the inner workings of the microtubule's lattice, based on recent experimental evidence for a conformational switch of the tubulin dimer. We show that the microtubule lattice itself coexists in discrete polymorphic states. Metastable curved states can be induced via a mechanical hysteresis involving torques and forces typical of few molecular motors acting in unison, in agreement with the observations.
Why microtubules run in circles: mechanical hysteresis of the tubulin lattice.
Ziebert, Falko; Mohrbach, Hervé; Kuli?, Igor M
2015-04-10
The fate of every eukaryotic cell subtly relies on the exceptional mechanical properties of microtubules. Despite significant efforts, understanding their unusual mechanics remains elusive. One persistent, unresolved mystery is the formation of long-lived arcs and rings, e.g., in kinesin-driven gliding assays. To elucidate their physical origin we develop a model of the inner workings of the microtubule's lattice, based on recent experimental evidence for a conformational switch of the tubulin dimer. We show that the microtubule lattice itself coexists in discrete polymorphic states. Metastable curved states can be induced via a mechanical hysteresis involving torques and forces typical of few molecular motors acting in unison, in agreement with the observations. PMID:25910164
Hidden hysteresis – population dynamics can obscure gene network dynamics
2013-01-01
Background Positive feedback is a common motif in gene regulatory networks. It can be used in synthetic networks as an amplifier to increase the level of gene expression, as well as a nonlinear module to create bistable gene networks that display hysteresis in response to a given stimulus. Using a synthetic positive feedback-based tetracycline sensor in E. coli, we show that the population dynamics of a cell culture has a profound effect on the observed hysteretic response of a population of cells with this synthetic gene circuit. Results The amount of observable hysteresis in a cell culture harboring the gene circuit depended on the initial concentration of cells within the culture. The magnitude of the hysteresis observed was inversely related to the dilution procedure used to inoculate the subcultures; the higher the dilution of the cell culture, lower was the observed hysteresis of that culture at steady state. Although the behavior of the gene circuit in individual cells did not change significantly in the different subcultures, the proportion of cells exhibiting high levels of steady-state gene expression did change. Although the interrelated kinetics of gene expression and cell growth are unpredictable at first sight, we were able to resolve the surprising dilution-dependent hysteresis as a result of two interrelated phenomena - the stochastic switching between the ON and OFF phenotypes that led to the cumulative failure of the gene circuit over time, and the nonlinear, logistic growth of the cell in the batch culture. Conclusions These findings reinforce the fact that population dynamics cannot be ignored in analyzing the dynamics of gene networks. Indeed population dynamics may play a significant role in the manifestation of bistability and hysteresis, and is an important consideration when designing synthetic gene circuits intended for long-term application. PMID:23800122
Improved charge amplifier using hybrid hysteresis compensation.
Amin-Shahidi, Darya; Trumper, David L
2013-08-01
We present a novel charge amplifier, with a robust feedback circuit and a method for compensating piezoelectric actuator's hysteresis at low frequencies. The amplifier uses a modified feedback circuit which improves robustness to the addition of series load impedance such as in cabling. We also describe a hybrid hysteresis compensation method for enabling the charge amplifier to reduce hysteresis at low frequencies. Experimental results demonstrate the utility of the new amplifier design. PMID:24007115
Applications of a theory of ferromagnetic hysteresis
Hodgdon, M.L.
1988-01-01
The differential equation B = ..cap alpha../vertical/ bar H /vertical bar/(f(H) - B) + Hg(H) and a set of restrictions on the material functions f and g yield a theory of rate independent hyseresis 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 H 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 MnZn ferrite, NiZn ferrite, NiFe tape, 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.
Reconfiguration and hysteresis in superconducting Nb film with honeycomb arrays
NASA Astrophysics Data System (ADS)
He, S. K.; Zhang, W. J.; Wen, Z. C.; Cao, W. H.
2012-12-01
Superconducting Nb films with honeycomb array of holes are studied using transport measurements. The oscillating magneto-resistance curves are observed up to large flux density. Two types of resistance minima with different field intervals are observed, indicating the reconfiguration of the overall flux lattice from honeycomb to triangular arrangement. Moreover, hysteretic effects are found in a very large field span from H = 2H1 to H = 8.5H1. It is revealed that the hysteresis is related to the presence of interstitial vortices.
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.
Cihan, Abdullah; Birkholzer, Jens; Trevisan, Luca; Bianchi, Marco; Zhou, Quanlin; Illangasekare, Tissa
2014-01-01
During CO2 injection and storage in deep reservoirs, the injected CO2 enters into an initially brine saturated porous medium, and after the injection stops, natural groundwater flow eventually displaces the injected mobile-phase CO2, leaving behind residual non-wetting fluid. Accurate modeling of two-phase flow processes are needed for predicting fate and transport of injected CO2, evaluating environmental risks and designing more effective storage schemes. The entrapped non-wetting fluid saturation is typically a function of the spatially varying maximum saturation at the end of injection. At the pore-scale, distribution of void sizes and connectivity of void space play a major role formore »the macroscopic hysteresis behavior and capillary entrapment of wetting and non-wetting fluids. This paper presents development of an approach based on the connectivity of void space for modeling hysteretic capillary pressure-saturation-relative permeability relationships. The new approach uses void-size distribution and a measure of void space connectivity to compute the hysteretic constitutive functions and to predict entrapped fluid phase saturations. Two functions, the drainage connectivity function and the wetting connectivity function, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model for saturation-capillary pressure is tested successfully by comparing the model-predicted residual saturation and scanning curves with actual data sets obtained from column experiments found in the literature. A numerical two-phase model simulator with the new hysteresis functions is tested against laboratory experiments conducted in a quasi-two-dimensional flow cell (91.4cm×5.6cm×61cm), packed with homogeneous and heterogeneous sands. Initial results show that the model can predict spatial and temporal distribution of injected fluid during the experiments reasonably well. However, further analyses are needed for comprehensively testing the ability of the model to predict transient two-phase flow processes and capillary entrapment in geological reservoirs during geological carbon sequestration.« less
Cihan, Abdullah [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Birkholzer, Jens [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Trevisan, Luca [Colorado School of Mines, Golden, CO (United States). Center for Experimental Study of Subsurface Environmental Processes (CESEP); Bianchi, Marco [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zhou, Quanlin [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Illangasekare, Tissa [Colorado School of Mines, Golden, CO (United States). Center for Experimental Study of Subsurface Environmental Processes (CESEP)
2014-12-31
During CO_{2} injection and storage in deep reservoirs, the injected CO_{2} enters into an initially brine saturated porous medium, and after the injection stops, natural groundwater flow eventually displaces the injected mobile-phase CO_{2}, leaving behind residual non-wetting fluid. Accurate modeling of two-phase flow processes are needed for predicting fate and transport of injected CO_{2}, evaluating environmental risks and designing more effective storage schemes. The entrapped non-wetting fluid saturation is typically a function of the spatially varying maximum saturation at the end of injection. At the pore-scale, distribution of void sizes and connectivity of void space play a major role for the macroscopic hysteresis behavior and capillary entrapment of wetting and non-wetting fluids. This paper presents development of an approach based on the connectivity of void space for modeling hysteretic capillary pressure-saturation-relative permeability relationships. The new approach uses void-size distribution and a measure of void space connectivity to compute the hysteretic constitutive functions and to predict entrapped fluid phase saturations. Two functions, the drainage connectivity function and the wetting connectivity function, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model for saturation-capillary pressure is tested successfully by comparing the model-predicted residual saturation and scanning curves with actual data sets obtained from column experiments found in the literature. A numerical two-phase model simulator with the new hysteresis functions is tested against laboratory experiments conducted in a quasi-two-dimensional flow cell (91.4cm×5.6cm×61cm), packed with homogeneous and heterogeneous sands. Initial results show that the model can predict spatial and temporal distribution of injected fluid during the experiments reasonably well. However, further analyses are needed for comprehensively testing the ability of the model to predict transient two-phase flow processes and capillary entrapment in geological reservoirs during geological carbon sequestration.
Contact Angle Hysteresis on Superhydrophobic Stripes
Alexander L. Dubov; Ahmed Mourran; Martin Möller; Olga I. Vinogradova
2014-07-21
We study experimentally and discuss quantitatively the contact angle hysteresis on striped superhydrophobic surfaces as a function of a solid fraction, $\\phi_S$. It is shown that the receding regime is determined by a longitudinal sliding motion the deformed contact line. Despite an anisotropy of the texture the receding contact angle remains isotropic, i.e. is practically the same in the longitudinal and transverse directions. The cosine of the receding angle grows nonlinearly with $\\phi_S$, in contrast to predictions of the Cassie equation. To interpret this we develop a simple theoretical model, which shows that the value of the receding angle depends both on weak defects at smooth solid areas and on the elastic energy of strong defects at the borders of stripes, which scales as $\\phi_S^2 \\ln \\phi_S$. The advancing contact angle was found to be anisotropic, except as in a dilute regime, and its value is determined by the rolling motion of the drop. The cosine of the longitudinal advancing angle depends linearly on $\\phi_S$, but a satisfactory fit to the data can only be provided if we generalize the Cassie equation to account for weak defects. The cosine of the transverse advancing angle is much smaller and is maximized at $\\phi_S\\simeq 0.5$. An explanation of its value can be obtained if we invoke an additional energy due to strong defects in this direction, which is shown to be proportional to $\\phi_S^2$. Finally, the contact angle hysteresis is found to be quite large and generally anisotropic, but it becomes isotropic when $\\phi_S\\leq 0.2$.
Negative and positive hysteresis in double-cavity optical bistability in a three-level atom
Babu, H. Aswath; Wanare, Harshawardhan
2011-03-15
We present dual hysteretic behavior of a three-level ladder system exhibiting optical bistability in a double-cavity configuration in the mean-field limit. The two fields coupling the atomic system experience competing cooperative effects along the two transitions. We observe a hump-like feature in the bistable curve arising due to cavity-induced inversion, which transforms into a negative-hysteresis loop. Apart from negative- and positive-hysteresis regions, the system offers a variety of controllable nonlinear dynamical features, ranging from switching, periodic self-pulsing to chaos.
Magnetic rotational hysteresis energy in the anisotropic Mn-Al-C permanent magnet
NASA Astrophysics Data System (ADS)
Wys?locki, J. J.
1986-04-01
The torque curves T, rotational hysteresis energy Wr and rotational hysteresis integral R have been analysed in an applied magnetic field Ha in order to obtain information on magnetization reversal processes of the anisotropic Mn-Al-C alloy. The results have been compared with the theoretical values obtained from the Stoner-Wohlfarth, Jacobs-Bean and Shtrikman-Treves theory. It is found that the results obtained in this work cannot be explained on the basis of the single-domain particle theory.
Bazghaleh, Mohsen Grainger, Steven; Cazzolato, Ben; Lu, Tien-Fu; Oskouei, Reza
2014-04-15
Smart actuators are the key components in a variety of nanopositioning applications, such as scanning probe microscopes and atomic force microscopes. Piezoelectric actuators are the most common smart actuators due to their high resolution, low power consumption, and wide operating frequency but they suffer hysteresis which affects linearity. In this paper, an innovative digital charge amplifier is presented to reduce hysteresis in piezoelectric stack actuators. Compared to traditional analog charge drives, experimental results show that the piezoelectric stack actuator driven by the digital charge amplifier has less hysteresis. It is also shown that the voltage drop of the digital charge amplifier is significantly less than the voltage drop of conventional analog charge amplifiers.
NASA Astrophysics Data System (ADS)
Bazghaleh, Mohsen; Grainger, Steven; Cazzolato, Ben; Lu, Tien-Fu; Oskouei, Reza
2014-04-01
Smart actuators are the key components in a variety of nanopositioning applications, such as scanning probe microscopes and atomic force microscopes. Piezoelectric actuators are the most common smart actuators due to their high resolution, low power consumption, and wide operating frequency but they suffer hysteresis which affects linearity. In this paper, an innovative digital charge amplifier is presented to reduce hysteresis in piezoelectric stack actuators. Compared to traditional analog charge drives, experimental results show that the piezoelectric stack actuator driven by the digital charge amplifier has less hysteresis. It is also shown that the voltage drop of the digital charge amplifier is significantly less than the voltage drop of conventional analog charge amplifiers.
The capillary hysteresis model HYSTR: User`s guide
Niemi, A.; Bodvarsson, G.S.
1991-11-01
The potential disposal of nuclear waste in the unsaturated zone at Yucca Mountain, Nevada, has generated increased interest in the study of fluid flow through unsaturated media. In the near future, large-scale field tests will be conducted at the Yucca Mountain site, and work is now being done to design and analyze these tests. As part of these efforts a capillary hysteresis model has been developed. A computer program to calculate the hysteretic relationship between capillary pressure {phi} and liquid saturation (S{sub 1}) has been written that is designed to be easily incorporated into any numerical unsaturated flow simulator that computes capillary pressure as a function of liquid saturation. This report gives a detailed description of the model along with information on how it can be interfaced with a transport code. Although the model was developed specifically for calculations related to nuclear waste disposal, it should be applicable to any capillary hysteresis problem for which the secondary and higher order scanning curves can be approximated from the first order scanning curves. HYSTR is a set of subroutines to calculate capillary pressure for a given liquid saturation under hysteretic conditions.
Hysteresis of unsaturated hydromechanical properties of a silty soil
Lu, Ning; Kaya, Murat; Collins, Brian D.; Godt, Jonathan W.
2013-01-01
Laboratory tests to examine hysteresis in the hydrologic and mechanical properties of partially saturated soils were conducted on six intact specimens collected from a landslide-prone area of Alameda County, California. The results reveal that the pore-size distribution parameter remains statistically unchanged between the wetting and drying paths; however, the wetting or drying state has a pronounced influence on the water-entry pressure, the water-filled porosity at zero suction, and the saturated hydraulic conductivity. The suction stress values obtained from the shear-strength tests under both natural moisture and resaturated conditions were mostly bounded by the suction stress characteristic curves (SSCCs) obtained from the hydrologic tests. This finding experimentally confirms that the soil-water retention curve, hydraulic conductivity function, and SSCC are intrinsically related.
Niemi, A.; Bodvarsson, G.S.
1991-11-01
As part of the code development and modeling work being carried out to characterize the flow in the unsaturated zone at Yucca Mountain, Nevada, capillary hysteresis models simulating the history-dependence of the characteristic curves have been developed. The objective of the work has been both to develop the hysteresis models, as well as to obtain some preliminary estimates of the possible hysteresis effects in the fractured rocks at Yucca Mountain given the limitations of presently available data. Altogether three different models were developed based on work of other investigators reported in the literature. In these three models different principles are used for determining the scanning paths: in model (1) the scanning paths are interpolated from tabulated first-order scanning curves, in model (2) simple interpolation functions are used for scaling the scanning paths from the expressions of the main wetting and main drying curves and in model (3) the scanning paths are determined from expressions derived based on the dependent domain theory of hysteresis.
Flexible, low-voltage, and low-hysteresis PbSe nanowire field-effect transistors.
Kim, David K; Lai, Yuming; Vemulkar, Tarun R; Kagan, Cherie R
2011-12-27
We report low-hysteresis, ambipolar bottom gold contact, colloidal PbSe nanowire (NW) field-effect transistors (FETs) by chemically modifying the silicon dioxide (SiO(2)) gate dielectric surface to overcome carrier trapping at the NW-gate dielectric interface. While water bound to silanol groups at the SiO(2) surface are believed to give rise to hysteresis in FETs of a wide range of nanoscale materials, we show that dehydration and silanization are insufficient in reducing PbSe NW FET hysteresis. Encapsulating PbSe NW FETs in cured poly(methyl) methacrylate (PMMA), dehydrates and uniquely passivates the SiO(2) surface, to form low-hysteresis FETs. Annealing predominantly p-type ambipolar PbSe NW FETs switches the FET behavior to predominantly n-type ambipolar, both with and without PMMA passivation. Heating the PbSe NW devices desorbs surface bound oxygen, even present in the atmosphere of an inert glovebox. Upon cooling, overtime oxygen readsorption switches the FET polarity to predominantly p-type ambipolar behavior, but PMMA encapsulation maintains low hysteresis. Unfortunately PMMA is sensitive to most solvents and heat treatments and therefore its application for nanostructured material deposition and doping is limited. Seeking a robust, general platform for low-hysteresis FETs we explored a variety of hydroxyl-free substrate surfaces, including silicon nitride, polyimide, and parylene, which show reduced electron trapping, but still large hysteresis. We identified a robust dielectric stack by assembling octadecylphosphonic acid (ODPA) on aluminum oxide (Al(2)O(3)) to form low-hysteresis FETs. We further integrated the ODPA/Al(2)O(3) gate dielectric stack on flexible substrates to demonstrate low-hysteresis, low-voltage FETs, and the promise of these nanostructured materials in flexible, electronic circuitry. PMID:22084980
Analysis of hunting in Synchronous Hysteresis Motor
Truong, Cang Kim, 1979-
2004-01-01
The Synchronous Hysteresis Motor has an inherent instability when it is used to drive a gyroscope wheel. The motor ideally should spin at a constant angular velocity, but it instead sporadically oscillates about synchronous ...
Hysteresis and nucleation in condensed matter
Yuri Mnyukh
2011-03-11
The physical origin of hysteresis in condensed matter had not been previously identified. The current "science of hysteresis" is useful, but limited by phenomenological modeling. This article fills the void by revealing the exclusive cause of the hysteresis in structural, ferromagnetic and ferroelectric phase transitions, as well as upon magnetization in magnetic fields and polarization in electric fields. This exclusive cause is nucleation lags. The lags are inevitable due to the nucleation specifics, far from the classical "random fluctuation" model. A major assumption that spin orientation is determined by the orientation of its carrier explains why ferromagnetic transitions and magnetization in magnetic fields materialize by structural rearrangements at interfaces, as well as why magnetization by "rotation" is impossible. Formation of the structural and ferromagnetic hysteresis loops is considered in detail.
HYSTERESIS AND VIBRATION COMPENSATION IN PIEZOELECTRIC
Fleming, Andrew J.
HYSTERESIS AND VIBRATION COMPENSATION IN PIEZOELECTRIC ACTUATORS BY INTEGRATING CHARGE CONTROL of Mechanical Engineering University of Washington Box 352600, Seattle, WA 98195, USA School of Electrical Engineering and Computer Science University of Newcastle University Drive, Callaghan, NSW 2308, Australia
ERIC Educational Resources Information Center
Rousseau, Ronald
1994-01-01
Discussion of informetric distributions shows that generalized Leimkuhler functions give proper fits to a large variety of Bradford curves, including those exhibiting a Groos droop or a rising tail. The Kolmogorov-Smirnov test is used to test goodness of fit, and least-square fits are compared with Egghe's method. (Contains 53 references.) (LRW)
Free boundaries in problems with hysteresis.
Apushkinskaya, D E; Uraltseva, N N
2015-09-13
Here, we present a survey concerning parabolic free boundary problems involving a discontinuous hysteresis operator. Such problems describe biological and chemical processes 'with memory' in which various substances interact according to hysteresis law. Our main objective is to discuss the structure of the free boundaries and the properties of the so-called 'strong solutions' belonging to the anisotropic Sobolev class [Formula: see text] with sufficiently large q. Several open problems in this direction are proposed as well. PMID:26261368
Hysteresis during contact angles measurement.
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
Hysteresis-corrected calibration of manganin under shock loading
Vantine, H.C.; Erickson, L.M.; Janzen, J.A.
1980-04-01
The coefficient of electrical resistance of manganin was measured under shock loading and ramp unloading. We made 64 measurements of loading stress in the 1.3--40.5-GPa range and 22 measurements of unloading stress in the 1.9--23.2-GPa range. The average loading coefficient was 14% larger than the average unloading coefficient: a clear measure of resistance hysteresis. The source of the hysteresis is attributed to an irreversible resistance change in manganin caused by shock damage. We present techniques to correct for the effects of this irreversible resistance change. With this correction, both loading and unloading levels showed the same average coefficient of resistance 0.02210.004 per GPa. Our unified calibration procedure can be very useful for analyzing complex stress signals that are produced, for example, by reactive shock waves.
Mettu, Srinivas; Chaudhury, Manoj K
2011-08-16
Hysteresis of wetting, like the Coulombic friction at solid/solid interface, impedes the motion of a liquid drop on a surface when subjected to an external field. Here, we present a counterintuitive example, where some amount of hysteresis enables a drop to move on a surface when it is subjected to a periodic but asymmetric vibration. Experiments show that a surface either with a negligible or high hysteresis is not conducive to any drop motion. Some finite hysteresis of contact angle is needed to break the periodic symmetry of the forcing function for the drift to occur. These experimental results are consistent with simulations, in which a drop is approximated as a linear harmonic oscillator. The experiment also sheds light on the effect of the drop size on flow reversal, where drops of different sizes move in opposite directions due to the difference in the phase of the oscillation of their center of mass. PMID:21728326
Effect of the Bering Strait on the AMOC hysteresis and glacial climate stability (Invited)
NASA Astrophysics Data System (ADS)
Hu, A.; Meehl, G. A.; Han, W.; Timmermann, A.; Otto-Bliesner, B. L.; Liu, Z.; Abe-Ouchi, A.
2013-12-01
Abrupt climate transitions, such as Dansgaard-Oeschger and Heinrich events, occurred frequently during the last glacial period, especially from 80 - 11 thousand years before present, but were nearly absent during Holocene and the early stages of last glacial period. Here we show, with a fully coupled climate model, that closing the Bering Strait and preventing its throughflow between the Pacific and Arctic Oceans during the glacial period can lead to the emergence of stronger hysteresis behavior of the Atlantic meridional overturning circulation (AMOC) to create conditions that are conducive to triggering abrupt climate transitions. Hence, it is argued that even for greenhouse warming, abrupt climate transitions similar to those in the last glacial time are unlikely to occur as the Bering Strait remains open. Qualitatively the same result is arrived in new simulations by employing the glacial background conditions using the same climate model. Theoretical and simulated AMOC hysteresis curves (a, b) and the associated changes of Greenland surface temperature and meridional heat transport at 65°N in the Atlantic (c, d). In panel a), 'S' is the bifurcation point beyond which AMOC collapses and the '+/-F' values indicate the freshwater forcing strength. In panels b), c), and d), the black/red (blue/green) lines are for the closed (open) BS simulation. The black/blue (red/green) lines represent the phase of freshwater forcing increase (decrease) in these simulations. Note that a change of the freshwater forcing by 0.1 Sv (Sv?106m3s-1) in this figure takes place over 500 model years.
Fatigue, hysteresis, and acoustic emission, parts 1 and 2
NASA Astrophysics Data System (ADS)
Guralnick, S. A.; Erber, T.
1992-05-01
The basic objective of this research program is to characterize the development of material fatigue by means of stress-strain hysteresis and acoustic emission measurements. We have conjectured that the accumulation and organization of damage in material fatigue is similar to the progressive failure of structures under cyclic loading. And, specifically, that the endurance limit of a material in fatigue is the analogue of the incremental collapse load of a structure. Since the principal features of the service life and failure of structures can be completely described by hysteresis methods, it is plausible that similar means can be used to characterize the inception and organization of microplastic processes in materials. Experiments were conducted upon nearly 100 specimens made of Rimmed AISI 1018 Unannealed Steel. This material was selected because extensive data on its performance exists in the engineering literature and because its stress-strain curve is of the gradual yielding type, mirroring at least the monotonic stress-strain behavior of many of the kinds of metals used in the aircraft industry.
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.
Photoinduced Contact Angle Hysteresis on a Single Microsphere
NASA Astrophysics Data System (ADS)
Rosenthal, Samuel; McGuiggan, Patricia
2011-11-01
An atomic force microscope (AFM) is used to measure the meniscus force on individual microspheres as they contact and are retracted from an air/liquid interface. The glass microspheres, whose radii ranged from 20 to 50 micrometers, had organic or inorganic coatings on their surfaces. By exposing the microspheres to light, the contact angle and thus the meniscus force could be dramatically altered. The measured force-distance curves are fitted to macroscopic wetting theory. From these measurements, the contact angle, contact angle hysteresis, position of the contact line pinning, and surface tension were simultaneously determined. Supported by the 3M non-tenured Faculty Grant and the National Science Foundation under Grant No. 0709187.
Digital signaling and hysteresis characterize Ras activation in lymphoid cells
Das, Jayajit; Ho, Mary; Zikherman, Julie; Govern, Christopher; Yang, Ming; Weiss, Arthur; Chakraborty, Arup K.; Roose, Jeroen P.
2009-01-01
Activation of Ras proteins underlies functional decisions in diverse cell types. Two molecules, RasGRP and SOS, catalyze Ras activation in lymphocytes. Binding of active Ras to SOS? allosteric pocket markedly increases SOS? activity establishing a positive feedback loop for SOS-mediated Ras activation. Integrating in silico and in vitro studies, we demonstrate that digital signaling in lymphocytes (cells are “on” or “off”) is predicated upon feedback regulation of SOS. SOS? feedback loop leads to hysteresis in the dose-response curve, which can enable a capacity to sustain Ras activation as stimuli are withdrawn and exhibit “memory” of past encounters with antigen. Ras activation via RasGRP alone is analog (graded increase in amplitude with stimulus). We describe how complementary analog (RasGRP) and digital (SOS) pathways act on Ras to efficiently convert analog input to digital output. Numerous predictions regarding the impact of our findings on lymphocyte function and development are noted. PMID:19167334
Investigations of magnetic hysteresis of barium ferrite using the torsion pendulum method
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.
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.
NSDL National Science Digital Library
2008-01-01
This page contains a discussion of ogive curves, logistic regression curves, and architecture. Nice photographs of architectural applications are included. The classic Birthday Problems is included as an example of an ogive curve.
Reduction of hysteresis in PI-controlled systems
Krakow, K.I.
1998-10-01
Motorized dampers and valves generally possess some hysteresis. Hysteresis may result in poor repeatability of experimental data. It also may result in the deviation of a response of a proportional integral (PI) controlled system from its target response and in hunting. In some applications, it may be desirable to reduce the effects of hysteresis. A method to reduce the effects of hysteresis is presented here. This method is based on software, not hardware, modification.
Sorption Hysteresis of Benzene in Charcoal Particles
Muzzio, Fernando J.
Sorption Hysteresis of Benzene in Charcoal Particles W A S H I N G T O N J . B R A I D A , , J O (benzene) in water to a maple- wood charcoal prepared by oxygen-limited pyrolysis at 673 K. Gas adsorption m2/g, and appreciable porosity in ultramicropores Benzene sorption- desorption conditions
NASA Astrophysics Data System (ADS)
Doster, F.; Joekar-Niasar, V.; Nordbotten, J. M.; Celia, M. A.
2011-12-01
The parameters and parameter functions of classical formulations of two-phase flow in porous media - the relative permeability - saturation relationship, the capillary pressure - saturation relationship, and the associated residual saturations - show path dependence, i.e. their values depend not only on the state variables but also on their drainage and imbibition history. Many models incorporate these hysteretic effects through ad-hoc adaptations based on fitting curves to experimental data. In addition, various physically based models identify different pore-scale phenomena as crucial. They range from Preisach-type models for dependent or independent domains, to identifying new state variables - e.g. interfacial area or non-percolating fluid saturations - to resolve hysteresis. Several models identify trapping and connectivity of fluids as an important contribution to macro-scale hysteresis. This is especially true for hysteresis in relative permeabilities. The trapping models propose trajectories from the initial saturation to the end saturation in various ways and are based on experiments or pore-network model results for the endpoints. However, experimental data or pore-scale model results are not available for the trajectories, i.e. the fate of the connectivity of the fluids while saturation changes. Hence, a validation of the different models is yet to be accomplished. Here, the impact of new results from a quasi-static pore-network model study on the change of the topology of the fluids during drainage and imbibition (see abstract: Trapping and hysteresis in two-phase flow in porous media 1: Pore-network modeling) on continuum scale models is discussed. The pore-network model results are compared to continuum-scale relationships from the literature and the consequences for the hysteresis models in which they are incorporated are evaluated. We find that while the models predict the qualitative trends they do not capture several interesting phenomena like a bifurcation depending on the connectivity of the remaining non-wetting phase at the endpoints of imbibition When one drainage follows one imbibition, the difference in fluid distributions due to this bifurcation is moderate. However, if the process type changes frequently, like in alternating injection scenarios for CO2 sequestration, models that do not include this phenomenon may lead to wrong estimates of trapped CO2.
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.
Mohammad Al Janaideh; Jianqin Mao; Subhash Rakheja; Wen-fang Xie; Chun-yi Su
2008-01-01
Smart actuators such as magneto-restrictive actuators, shape memory alloy (SMA) actuators, and piezoceramic actuators exhibit different hysteresis loops. In this paper, a generalized Prandtl-Ishlinskii model is utilized for modeling and compensation of hysteresis nonlinearities in smart actuators. In the formulated model, a generalized play operator together with a density is integrated to form the generalized Prandtl-Ishlinskii model. The capability of
Basin of Attraction Determines Hysteresis in Explosive Synchronization
Yong Zou; Tiago Pereira; Michael Small; Zonghua Liu; Jürgen Kurths
2014-02-11
Spontaneous explosive emergent behavior takes place in heterogeneous networks when the frequencies of the nodes are positively correlated to the node degree. A central feature of such explosive transitions is a hysteretic behavior at the transition to synchronization. We unravel the underlying mechanisms and show that the dynamical origin of the hysteresis is a change of basin of attraction of the synchronization state. Our findings hold for heterogeneous networks with star graph motifs such as scale free networks, and hence reveal how microscopic network parameters such as node degree and frequency affect the global network properties and can be used for network design and control.
Origin of hysteresis in bed form response to unsteady flows
NASA Astrophysics Data System (ADS)
Martin, Raleigh L.; Jerolmack, Douglas J.
2013-03-01
Field and laboratory studies indicate that changes in riverbed morphology often lag changes in water discharge. This lagged response produces hysteresis in the relationship between water discharge and bed form geometry. To understand these phenomena, we performed flume experiments to observe the response of a sand bed to step increases and decreases in water discharge. For an abrupt rise in discharge, we observed that bed forms grew rapidly by collision and merger of bed forms migrating with different celerities. Growth rate slowed as bed forms approached equilibrium with the higher discharge regime. After an abrupt discharge drop, bed form decay occurred through formation of smaller secondary bed forms, in equilibrium with the lower discharge, which cannibalized the original, relict features. We present a simple model framework to quantitatively predict time scales of bed form adjustment to flow changes, based on equilibrium bed form heights, lengths, and celerities at low and high flows. For rising discharge, the model assumes that all bed form collisions result in irreversible merger, due to a dispersion of initial celerities. For falling discharge, we derive a diffusion model for the decay of relict high-stage features. Our models predict the form and time scale of experimental bed form adjustments. Additional experiments applying slow and fast triangular flood waves show that bed form hysteresis occurs only when the time scale of flow change is faster than the modeled (and measured) bed form adjustment time. We show that our predicted adjustment time scales can also be used to predict the occurrence of bed form hysteresis in natural floods.
Stochastic hysteresis and resonance in a kinetic Ising system
Sides, S.W.; Rikvold, P.A. [Center for Materials Research and Technology and Department of Physics, Florida State University, Tallahassee, Florida 32306-4350 (United States)] [Center for Materials Research and Technology and Department of Physics, Florida State University, Tallahassee, Florida 32306-4350 (United States); Sides, S.W.; Rikvold, P.A.; Novotny, M.A. [Supercomputer Computations Research Institute, Florida State University, Tallahassee, Florida 32306-4130 (United States)] [Supercomputer Computations Research Institute, Florida State University, Tallahassee, Florida 32306-4130 (United States); Sides, S.W.; Rikvold, P.A. [Colorado Center for Chaos and Complexity, University of Colorado, Boulder, Colorado 80309-0216 (United States)] [Colorado Center for Chaos and Complexity, University of Colorado, Boulder, Colorado 80309-0216 (United States)
1998-06-01
We study hysteresis for a two-dimensional, spin-1/2, nearest-neighbor, kinetic Ising ferromagnet in an oscillating field, using Monte Carlo simulations and analytical theory. Attention is focused on small systems and weak field amplitudes at a temperature below T{sub c}. For these restricted parameters, the magnetization switches through random nucleation of a {ital single} droplet of spins aligned with the applied field. We analyze the stochastic hysteresis observed in this parameter regime, using time-dependent nucleation theory and the theory of variable-rate Markov processes. The theory enables us to accurately predict the results of extensive Monte Carlo simulations, without the use of any adjustable parameters. The stochastic response is qualitatively different from what is observed, either in mean-field models or in simulations of larger spatially extended systems. We consider the frequency dependence of the probability density for the hysteresis-loop area and show that its average slowly crosses over to a logarithmic decay with frequency and amplitude for asymptotically low frequencies. Both the average loop area and the residence-time distributions for the magnetization show evidence of stochastic resonance. We also demonstrate a connection between the residence-time distributions and the power spectral densities of the magnetization time series. In addition to their significance for the interpretation of recent experiments in condensed-matter physics, including studies of switching in ferromagnetic and ferroelectric nanoparticles and ultrathin films, our results are relevant to the general theory of periodically driven arrays of coupled, bistable systems with stochastic noise. {copyright} {ital 1998} {ital The American Physical Society}
Gershenzon, Naum I; Dominic, David F; Mehnert, Edward; Okwen, Roland T
2015-01-01
Geological heterogeneities essentially affect the dynamics of a CO2 plume in subsurface environments. Previously we showed how the dynamics of a CO2 plume is influenced by the multi-scale stratal architecture in deep saline reservoirs. The results strongly suggest that representing small-scale features is critical to understanding capillary trapping processes. Here we present the result of simulation of CO2 trapping using two different conventional approaches, i.e. Brooks-Corey and van Genuchten, for the capillary pressure curves. We showed that capillary trapping and dissolution rates are very different for the Brooks-Corey and van Genuchten approaches when heterogeneity and hysteresis are both represented.
Contact angle hysteresis in electrowetting on dielectric
NASA Astrophysics Data System (ADS)
Zhao, Rui; Liu, Qi-Chao; Wang, Ping; Liang, Zhong-Cheng
2015-08-01
Contact angle hysteresis (CAH) is one of the significant physical phenomena in electrowetting on dielectric (EWOD). In this work, a theoretical model is proposed to characterize electrowetting evolution on substrates with CAH, and the relationship among apparent contact angle, potential, and some other parameters is quantified. And this theory is also validated experimentally. The results indicate that our theory and equation based on energy balance succeed in describing the electrowetting response of potential with significant contact angle hysteresis. The CAH in EWOD, ranging from 0° to about 20° in electrowetting cycle, increases with the increase of voltage and climbs up to about 20° when voltage is increased to about 38 V, and then decreases to zero with the further increase of voltage. Project supported by the Natural Science Foundation of Jiangsu Province, China (Grant No. BK2011752).
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.
Tribology and ultrasonic hysteresis at local scales
NASA Astrophysics Data System (ADS)
Szoszkiewicz, R.; Huey, B. D.; Kolosov, O. V.; Briggs, G. A. D.; Gremaud, G.; Kulik, A. J.
2003-03-01
Local adhesion hysteresis (AH) is difficult to measure using an AFM due to complications introduced by compliant cantilevers as they snap-in and snap-out to/from a sample surface. But, at ultrasonic frequencies well above the cantilever mechanical resonance, the effective stiffness can increase enormously. Therefore, ultrasonically vibrating a sample in contact with an AFM tip can probe the hysteretic cycle of tip-sample in- and out-interactions [Jpn. J. Appl. Phys. 32 (1993) 22; Acoust. Imag. (1996)] allowing AH to be investigated by measuring ultrasonic hysteresis (UH). For the first time UH is compared here with lateral force microscopy (LFM) data. The same kind of experiments is also implemented for a nanoindenter based setup. Thus, the micro- (nanoindenter) and nano- (AFM) scales are investigated. UH and friction of both length scales are found to be linearly related for surfaces differing widely in elasticity and adhesion.
NASA Astrophysics Data System (ADS)
Mc Namara, Hugh A.; Pokrovskii, Alexei V.
2006-02-01
The Kaldor model-one of the first nonlinear models of macroeconomics-is modified to incorporate a Preisach nonlinearity. The new dynamical system thus created shows highly complicated behaviour. This paper presents a rigorous (computer aided) proof of chaos in this new model, and of the existence of unstable periodic orbits of all minimal periods p>57.
Studies of hysteresis in two-dimensional kinetic Ising model using the FORC technique
NASA Astrophysics Data System (ADS)
Robb, Daniel; Novotny, Mark; Rikvold, Per Arne
2004-03-01
We describe the FORC (first order reversal curve) technique [1] for hysteresis, first developed as an experimental method to better characterize magnetic materials, and present FORC distributions for simulations of a square-lattice kinetic Ising model. To understand the simulation results, we apply a theory of magnetization reversal for the multidroplet (MD) regime [2] for homogeneous nucleation and growth, also called the Kolmogorov-Johnson-Mehl-Avrami regime. The FORC `partial hysteresis' loops exhibit different properties than those of systems with strong disorder [1]. We compare the simulation and the theory for several lattice sizes, frequencies of the external field, and temperatures. [1] C.R. Pike, A.P. Roberts, and K.L. Verosub, J. Appl. Phys. 85, 6660 (1999). [2] S.W. Sides, P.A. Rikvold, and M.A. Novotny, Phys. Rev. E 59, 2710 (1999).
Bazghaleh, Mohsen; Grainger, Steven; Cazzolato, Ben; Lu, Tien-Fu; Oskouei, Reza
2014-04-01
Smart actuators are the key components in a variety of nanopositioning applications, such as scanning probe microscopes and atomic force microscopes. Piezoelectric actuators are the most common smart actuators due to their high resolution, low power consumption, and wide operating frequency but they suffer hysteresis which affects linearity. In this paper, an innovative digital charge amplifier is presented to reduce hysteresis in piezoelectric stack actuators. Compared to traditional analog charge drives, experimental results show that the piezoelectric stack actuator driven by the digital charge amplifier has less hysteresis. It is also shown that the voltage drop of the digital charge amplifier is significantly less than the voltage drop of conventional analog charge amplifiers. PMID:24784651
ERIC Educational Resources Information Center
Gehring, John
2004-01-01
For the past 16 years, the blue-collar city of Huntington, West Virginia, has rolled out the red carpet to welcome young wrestlers and their families as old friends. They have come to town chasing the same dream for a spot in what many of them call "The Show". For three days, under the lights of an arena packed with 5,000 fans, the state's best…
Mechanical Hysteresis as AN Nde Tool for Evaluating Composite Honeycomb Damage
NASA Astrophysics Data System (ADS)
Foreman, Cory D.; Dayal, Vinay; Barnard, Daniel J.; Hsu, David K.
2009-03-01
Honeycomb composites are finding ever increasing use on aircraft structures, making nondestructive detection of defects contained within honeycomb structures all the more important. This paper focuses on a new detection technique which makes use of the mechanical hysteresis seen as loops in the force-displacement curves. It was observed from load test data that internal damage in honeycomb sandwiches causes the average slope of the force-displacement curves to decrease and the area contained within the hysteresis loop to increase. To satisfy the inspection speed and one-sided access requirements of NDE techniques, a dynamic loading approach was pursued where an accelerometer was used to tap the surface of the test sample. Much of the research focused on the deduction of the force-displacement curves from an acceleration curve. This greatly increased the speed of the technique as well as reduced it to a one-sided test, where only access to the outer surface of the structure is needed.
Rheological Hysteresis in Soft Glassy Materials
NASA Astrophysics Data System (ADS)
Divoux, Thibaut; Grenard, Vincent; Manneville, Sébastien
2013-01-01
The nonlinear rheology of a soft glassy material is captured by its constitutive relation, shear stress versus shear rate, which is most generally obtained by sweeping up or down the shear rate over a finite temporal window. For a huge amount of complex fluids, the up and down sweeps do not superimpose and define a rheological hysteresis loop. By means of extensive rheometry coupled to time-resolved velocimetry, we unravel the local scenario involved in rheological hysteresis for various types of well-studied soft materials. We introduce two observables that quantify the hysteresis in macroscopic rheology and local velocimetry, respectively, as a function of the sweep rate ?t-1. Strikingly, both observables present a robust maximum with ?t, which defines a single material-dependent time scale that grows continuously from vanishingly small values in simple yield stress fluids to large values for strongly time-dependent materials. In line with recent theoretical arguments, these experimental results hint at a universal time scale-based framework for soft glassy materials, where inhomogeneous flows characterized by shear bands and/or pluglike flow play a central role.
Dynamic response and hysteresis dispersion scaling of ferroelectric SrBi2Ta2O9 thin films
NASA Astrophysics Data System (ADS)
Pan, B.; Yu, H.; Wu, D.; Zhou, X. H.; Liu, J.-M.
2003-08-01
The dynamic hysteresis response of ferroelectric SrBi2Ta2O9 thin films versus periodically varying electric field over a frequency range of f=10-1-106 Hz and amplitude range of E0=15-158 kV/cm is measured utilizing the Sawyer-Tower method. The dynamic order parameter Q shows anomalous behavior against the field amplitude, and a single-peaked hysteresis dispersion is identified. The field response of hysteresis area in the form of ?f2/3E02/3 over the low frequency range is evaluated, while the response over the high frequency range takes the form of ?f-1/3E02. We demonstrate that the hysteresis dispersion spectrum exhibits single-parameter scaling, and predicts a characteristic time for domain reversal that is inversely correlated to the field amplitude.
Modeling Hysteresis Effect in Three-Phase Relative Permeability
NASA Astrophysics Data System (ADS)
Kianinejad, A.; Chen, X.; DiCarlo, D. A.
2014-12-01
Simulation and fluid flow prediction of many petroleum enhanced oil recovery methods as well as environmental processes such as carbon dioxide (CO2) geological storage requires accurate modeling and determination of relative permeability under different saturation histories. Based on this critical need, there has been several different three-phase relative permeability models developed to predict the hysteresis effects in relative permeability, most of which requiring many different parameters which introduce extreme complexity to the models for practical purposes. In this work, we experimentally measured three-phase, water/oil/gas, relative permeability in a 1-m long water-wet sand pack, under several different flow histories. We measured the in-situ saturations along the sand pack using a CT scanner. We then determined the relative permeabilities directly from the measured in-situ saturations, using unsteady-state method. Based on our results, good estimation of residual saturations yields in excellent three-phase relative permeability estimations by just using the simple, standard relative permeability models such as, Saturation Weighted Interpolation (SWI), Corey's and Stones. Our results show that, the key parameter to model the hysteresis in three-phase relative permeability (effect of saturation history) is the residual saturations. Once the residual saturations were correctly determined for each specific saturation path, the standard relative permeability models can predict the three-phase relative permeabilities perfectly.
Perceptual hysteresis as a marker of perceptual inflexibility in schizophrenia.
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
Identification of Quaternary Shape Memory Alloys with Near-Zero Thermal Hysteresis and Unprecedented
Rubloff, Gary W.
Identification of Quaternary Shape Memory Alloys with Near-Zero Thermal Hysteresis fatigue of shape memory alloys (SMAs) resulting in changes of physical, mechan- ical, and shape memory (SM the class of materials showing a reversible martensitic phase transformation and a shape memory effect (SME
Harrison, S M; Lamont, C; Miller, D J
1988-01-01
1. The relationship between pCa (-log10[Ca2+]) and steady-state isometric tension has been investigated in saponin- or Triton-treated (chemically 'skinned') cardiac muscle of rat. 2. Hysteresis exists in the relationship such that the muscle is less sensitive to Ca2+ during increasing activation (as [Ca2+] is stepped upward) than during reducing activation (as [Ca2+] is stepped downward). 3. The extent of the hysteresis is insensitive to interventions that increase overall calcium sensitivity by chemical means, such as caffeine, carnosine or increased pH. 4. The extent of the hysteresis is sensitive to sarcomere length. The phenomenon is virtually absent above sarcomere lengths of about 2.2-2.3 microns but becomes progressively greater at shorter sarcomere lengths. 5. The effect of sarcomere length on calcium sensitivity is restricted to the upward-going (increasing activation) part of the pCa-tension loop below 2.2 microns. The downward-going (decreasing activation) part of the hysteretic relationship is virtually unaffected by sarcomere length up to 2.2 microns. 6. Significant alterations in sarcomere length do not occur during tension development in the experiments described here: the phenomenon is not attributable to experimental artifacts of this kind. 7. Hysteresis develops sufficiently rapidly to be consistent with a physiological relevance during the normal heart beat. 8. The effects of sarcomere length show that the phenomenon is not due to force per se since, for example, greater peak force produces less hysteresis as sarcomere length is increased towards 2.2 microns. 9. Tonicity increase (by high-molecular-weight dextran), which shrinks the myofilament lattice, increases calcium sensitivity but reduces the effect of sarcomere length on calcium sensitivity. 10. The results suggest that lattice shrinkage is the mechanism which accounts for hysteresis in, and the sarcomere length dependence of, calcium sensitivity in cardiac muscle. Images Fig. 1 Fig. 11 PMID:3171985
Conformational Electroresistance and Hysteresis in Nanoclusters
Li, Xiangguo; Zhang, Xiaoguang; Cheng, Hai-Ping
2014-01-01
Among many mechanisms proposed for electroresistance, ones involving structural changes are the least understood because of challenges of controllability and repeatability. Yet structural changes can cause dramatic changes in electronic properties, leading to multiple ways in which conduction paths can be opened and closed, not limited to filament movement or variation in molecular conductance. Here we show at least another way: conformational dependence of the Coulomb charging energy of a nanocluster, where charging induced conformational distortion changes the blockade voltage, which in turn leads to a giant electroresistance. This intricate interplay between charging and conformation change is demonstrated in a nanocluster Zn3O4 by combining a first-principles calculation with a temperature dependent transport model. The predicted hysteretic Coulomb blockade staircase in the current-voltage curve adds another dimension to the rich phenomenon of tunneling electroresistance. The new mechanism also provides a better controlled and repeatable platform to study conformational electroresistance.
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.
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.
Hysteresis prediction inside magnetic shields and application
Mori?, Igor [Observatoire de Paris, SYRTE, Avenue Denfert 77, 75014 Paris (France); CNES, Edouard Belin 18, 31400 Toulouse (France); De Graeve, Charles-Marie [SOGETI High Tech, chemin Laporte 3, 31300 Toulouse (France); Grosjean, Olivier [CNES, Edouard Belin 18, 31400 Toulouse (France); Laurent, Philippe [Observatoire de Paris, SYRTE, Avenue Denfert 77, 75014 Paris (France)
2014-07-15
We have developed a simple model that is able to describe and predict hysteresis behavior inside Mumetal magnetic shields, when the shields are submitted to ultra-low frequency (<0.01 Hz) magnetic perturbations with amplitudes lower than 60??T. This predictive model has been implemented in a software to perform an active compensation system. With this compensation the attenuation of longitudinal magnetic fields is increased by two orders of magnitude. The system is now integrated in the cold atom space clock called PHARAO. The clock will fly onboard the International Space Station in the frame of the ACES space mission.
Monopoles, Curves and Ramanujan
H. W. Braden; V. Z. Enolski
2007-04-30
We develop the Ercolani-Sinha construction of SU(2) monopoles and make this effective for (a five parameter family of centred) charge 3 monopoles. In particular we show how to solve the transcendental constraints arising on the spectral curve. For a class of symmetric curves the transcendental constraints become a number theoretic problem and a recently proven identity of Ramanujan provides a solution.
Educational software for the numerical correction of experimental magnetization curves
Valentin Ionita; Emil Cazacu
2010-01-01
The proposed software allows students to get aware of the importance of the experimental data accuracy in magnetism. A common error source for the magnetization curves (including hysteresis cycles) is the demagnetization effect and the influence of the magnetic sensor position. Our software helps the user to understand the principle and the effect of each correction method. The Graphical User
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.
Modeling Loading/Unloading Hysteresis Behavior of Unidirectional C/SiC Ceramic Matrix Composites
NASA Astrophysics Data System (ADS)
Longbiao, Li; Yingdong, Song; Youchao, Sun
2013-08-01
The loading/unloading tensile behavior of unidirectional C/SiC ceramic matrix composites at room temperature has been investigated. The loading/unloading stress-strain curve exhibits obvious hysteresis behavior. An approach to model the hysteresis loops of ceramic matrix composites including the effect of fiber failure during tensile loading has been developed. By adopting a shear-lag model which includes the matrix shear deformation in the bonded region and friction in the debonded region, the matrix cracking space and interface debonded length are obtained by matrix statistical cracking model and fracture mechanics interface debonded criterion. The two-parameter Weibull model is used to describe the fiber strength distribution. The stress carried by the intact and fracture fibers on the matrix crack plane during unloading and subsequent reloading is determined by the Global Load Sharing criterion. Based on the damage mechanisms of fiber sliding relative to matrix during unloading and subsequent reloading, the unloading interface reverse slip length and reloading interface new slip length are obtained by the fracture mechanics approach. The hysteresis loops of unidirectional C/SiC ceramic matrix composites corresponding to different stress have been predicted.
Feedforward Controller of Ill-Conditioned Hysteresis Using Singularity-Free Prandtl–Ishlinskii Model
Tan, U-Xuan; Latt, Win Tun; Shee, Cheng Yap; Riviere, Cameron N.; Ang, Wei Tech
2009-01-01
Piezoelectric, magnetostrictive, and shape memory alloy actuators are gaining importance in high-frequency precision applications constrained by space. Their intrinsic hysteretic behavior makes control difficult. The 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
An inclusive model of ferromagnetic hysteresis
NASA Astrophysics Data System (ADS)
Phelps, Brian Fletcher
A new inclusive macroscopic model of ferromagnetic hysteresis is proposed. The model is developed from a Stoner-Wohlfarth approach by adding mean field or nearest neighbour dipole-dipole interactions. Pinning of domain rotation is also postulated, and a rotational pinning extension included. The model includes the principal features of the Jiles-Atherton model in the previous Atherton-Beattie extension of the Stoner-Wohlfarth model, but still omits the domain wall energy effects included in the Globus model. The new model describes both reversible and irreversible processes, and hysteresis caused by combinations of interaction, anisotropy, and pinning. Computational approaches to both two and three dimensional calculations are detailed, and examples given. Simulations of hard magnetic materials are done, including major loops to near saturation, minor loops, and demagnetizations. The complete 2 x 2 magnetization tensor response is shown, including fan diagram representations. The minor loop simulations involve complicated sets of field turning points typical of the Preisach model, and the minor loops are seen to exhibit incongruence and eventual closure. The demagnetization simulations are done for both rotating and oscillating applied field cycles. Both isotropic and anisotropic polycrystalline easy axis distributions are treated.
Preisach modeling of piezoceramic and shape memory alloy hysteresis
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
A Domain Wall Model for Hysteresis in Piezoelectric Materials
A Domain Wall Model for Hysteresis in Piezoelectric Materials Ralph C. Smith Center for Research constitutive relations in piezoelec tric materials at moderate to high drive levels. Hysteresis and nonlinearities are due to the domain structure inherent to the materials and both aspects must be addressed
CAPILLARY DROPS: CONTACT ANGLE HYSTERESIS AND STICKING DROPS
Mellet, Antoine
CAPILLARY DROPS: CONTACT ANGLE HYSTERESIS AND STICKING DROPS L. A. CAFFARELLI AND A. MELLET to a contact angle condition of the form cos [1, 2], which justifies the so-called contact angle hysteresis denotes the mean-curvature of the free surface E, and a contact angle condition, known as Young
Using Hysteresis to Improve Performance in Synchronous Networks Tirunelveli Anand
Minai, Ali A.
of synchronous attractor networks of hysteretic thresh- old elements. The addition of hysteresis is known network loading (ratio of patterns stored to network size), there is an optimal value of hysteresis" can be used to en- hance the performance of attractor networks. 1. Introduction Attractor networks 5
Fatigue life prediction under random loading using total hysteresis energy
D. S. Tchankov; K. V. Vesselinov
1998-01-01
The fatigue life prediction under random loading is an important problem and a solution based on total hysteresis energy to failure is presented here. An incremental approach for estimation of the hysteresis energy during the random loading and hence a new approach for fatigue life prediction was developed. This approach does not require any cycle counting procedure. An experimental verification
Application of the Preisach model in soil-moisture hysteresis
Schellekens, Michel P.
Application of the Preisach model in soil-moisture hysteresis Denis Flynn, Hugh McNamara, Philip O- teresis effects in the relation between water retention and soil-moisture ten- sion. Special, one parameter, classes of Preisach operators are proposed to construct models of the soil-moisture hysteresis
ORIGINAL ARTICLE The impacts of hysteresis on variably saturated hydrologic
Borja, Ronaldo I.
ORIGINAL ARTICLE The impacts of hysteresis on variably saturated hydrologic response and slope, variably satu- rated subsurface flow simulation to examine hysteretic effects upon the hydrologic response the near-sur- face hydrologic response and subsequently the potential for slope failure. If hysteresis
Mathematical models of hydrological systems with Preisach hysteresis
Schellekens, Michel P.
the water cycle leads to an operator-differential PDE, which is a modification of the Philip is known for a long time. Hysteresis manifests itself through the fact that it is easier (i.e., less thermo-mechanical work is required) to put water into soil than to remove it afterwards. The nature of this hysteresis
The field and temperature dependence of hysteresis loops in P(VDF-TrFE) copolymer films
NASA Astrophysics Data System (ADS)
Mai, Manfang; Leschhorn, Andreas; Kliem, Herbert
2015-01-01
The ferroelectric hysteresis loops of poly(vinylidene fluoride/trifluoethylene) [P(VDF-TrFE)] copolymer films are investigated as a function of external field and temperature. Starting from a plateau at the low frequency side the coercive field increases with increasing frequency. It exhibits a maximum in the kHz-range and decreases then. The remanent polarization is almost constant at low frequencies and decreases above the kHz-range. For a constant frequency, the coercive field increases with increasing the amplitude of the external field. Furthermore, the hysteresis loops at different temperatures at a given frequency and amplitude exhibit a linear decrease of coercive field with increasing temperature. A double hysteresis loop is observed close to the Curie point and a sharp jump of the remanent polarization is obtained in samples as thick as 600 nm indicating a first order phase transition. For samples as thin as 90 nm, the double hysteresis loop of the polarization is absent and the change of remanent polarization dependent on temperature is smoother. The above experimental results can be explained and simulated in the Weiss mean field model. The simulation results are compared with the experiments and show a good consistency.
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.
Hysteresis Compensation for a Piezo Deformable Mirror - Poster Paper
NASA Astrophysics Data System (ADS)
Song, H.; Fraanje, R.; Schitter, G.; Verhaegen, M.; Vdovin, G.
2008-01-01
The field of adaptive optics (AO) has received rapidly increasing attention in recent years, the intrinsic hysteresis of the piezo deformable mirror (DM) imposes a limit in the accuracy when the stroke of the piezo-actuator is on the order of micrometers. This contribution discusses the hysteresis compensation of a piezo DM by an inverse Preisach hysteresis model. The inverse Preisach hysteresis model is identified from the measured input-output data with a neural network and with a hinging hyperplane based approach. Experimental results demonstrate that hysteresis of the piezo-actuator can be reduced from 20% to about 6% and 9% by the neural network and by the hinging hyperplanes, respectively.
A Model for RateDependent Hysteresis in Piezoceramic Materials Operating at Low Frequencies
to balance the electrostatic and thermal energy. Hysteresis is then incorporated through the quantification employed models for hysteresis in ferroelectric materials are based on the assumption of static
Terrestrial Exoplanet Light Curves
Eric Gaidos; Nicholas Moskovitz; Darren M. Williams
2005-11-23
The phase or orbital light curves of extrasolar terrestrial planets in reflected or emitted light will contain information about their atmospheres and surfaces complementary to data obtained by other techniques such as spectrosopy. We show calculated light curves at optical and thermal infrared wavelengths for a variety of Earth-like and Earth-unlike planets. We also show that large satellites of Earth-sized planets are detectable, but may cause aliasing effects if the lightcurve is insufficiently sampled.
Hysteresis and precession of a swirling jet normal to a wall.
Shtern, V; Mi, J
2004-01-01
Interaction of a swirling jet with a no-slip surface has striking features of fundamental and practical interest. Different flow states and transitions among them occur at the same conditions in combustors, vortex tubes, and tornadoes. The jet axis can undergo precession and bending in combustors; this precession enhances large-scale mixing and reduces emissions of NOx. To explore the mechanisms of these phenomena, we address conically similar swirling jets normal to a wall. In addition to the Serrin model of tornadolike flows, a new model is developed where the flow is singularity free on the axis. New analytical and numerical solutions of the Navier-Stokes equations explain occurrence of multiple states and show that hysteresis is a common feature of wall-normal vortices or swirling jets no matter where sources of motion are located. Then we study the jet stability with the aid of a new approach accounting for deceleration and nonparallelism of the base flow. An appropriate transformation of variables reduces the stability problem for this strongly nonparallel flow to a set of ordinary differential equations. A particular flow whose stability is studied in detail is a half-line vortex normal to a rigid plane-a model of a tornado and of a swirling jet issuing from a nozzle in a combustor. Helical counter-rotating disturbances appear to be first growing as Reynolds number increases. Disturbance frequency changes its sign along the neutral curve while the wave number remains positive. Short disturbance waves propagate downstream and long waves propagate upstream. This helical instability causes bending of the vortex axis and its precession-the effects observed in technological flows and in tornadoes. PMID:14995717
NASA Astrophysics Data System (ADS)
Van der Perk, M.; Vogels, M. F. A.
2012-04-01
Concentration rating curves are useful for the analysis of the response of sediment or solute concentrations to changes in stream discharge or for the interpolation of infrequent concentration measurements in time with discharge as auxiliary variable, for example to estimate annual sediment or solute loads. A known limitation of rating curves is that their performance is generally poor, which can be partly attributed to the fact that rating curve methods neglect the hysteresis effects in the concentration response to changes in discharge. To enhance the performance of rating curve models, they should account for these hysteresis effects. Here, we present a supply-based concentration rating curve for total phosphorus concentrations in the Rhine River, the Netherlands, which does account for the above hysteresis effects. The supply-based concentration rating curve has four components: 1) The traditional power law rating curve of the form C = a Qb where C is the phosphorus concentration [M L-3], Qis the river discharge [L T-1], and a and b are constants [-]; 2) A long-term linear trend; 3) A seasonal trend of the form C(t) = Acos [2?(t - Tk)/T] where A is the concentration amplitude [M L-3], t is the time (T), Tk is the phase shift (T), and T is the period [T] (365.25 d). 4) A discharge dependent supply or loss term of the form C = -?S/(Q?t), where S is the phosphorus stock [M]. The phosphorus stock was assumed to increase linearly during periods of deposition, i.e. the discharge is below a critical discharge. If the discharge is greater than the critical discharge during a sufficiently long period (> 16 days), the decrease in phosphorus stock was assumed to be proportional to the excess discharge above the critical discharge. For model parameterization and calibration, we used the daily Aqualarm data of total phosphorus concentrations and the Waterbase data of water discharge measured daily by Rijkswaterstaat (Dutch Ministry of Infrastructure and the Environment) at the Lobith-Bimmen monitoring station at the German-Dutch border between 1 April 2004 and 20 July 2010. The model parameters were calibrated by a step-wise procedure which involved in some steps visual calibration (e.g. concentration amplitude, critical discharge for erosion/deposition) and in other steps regression analysis (e.g. long-term linear trend, power law rating curve). The total phosphorus concentrations show a long-term linear decrease of 1.0 - 10-5 mg l-1 d-1. The amplitude of the seasonal fluctuation in phosphorus concentration was estimated to be 0.03 mg l-1. The critical discharge for erosion and deposition was estimated to be 1900 m s-1, the increase in phosphorus stock during deposition periods 9300 kg d-1, and the supply from the phosphorus stock to the river water 32 kg d-1per m3 s excess discharge. The squared Pearson's correlation coefficient between the observed and predicted total phosphorus increased from 0.16 for the traditional power-law concentration rating curve (Nash's efficiency coefficient = 0.13) to 0.36 for the supply-based rating curve (Nash's efficiency coefficient = 0.34). This implies that inclusion of the long-term and seasonal trends and a discharge dependent supply and loss term considerably enhances the performance and predictive power of the concentration rating curve model. As the response to changes in discharge is different for dissolved and particulate total phosphorus, a further improvement of model performance can likely be achieved by deriving separate concentration rating curves for dissolved total phosphorus and sediment-associated phosphorus.
NSDL National Science Digital Library
2013-02-12
This is a game about light curves that will test your ability to figure out things about an asteroid from just a graph of its brightness. Astronomers use telescopes to collect light curves - measurements of the brightness of distant asteroids over time. It is part of the Killer Asteroids Web Site. The site also features a background overview of the differences between asteroids and comets, information on different types of asteroids (rubble piles vs monoliths), a discussion of how at risk Earth really is to an asteroid or comet impact, and background information on light curves.
Thermal hysteresis behaviors of thermoelectric properties
NASA Astrophysics Data System (ADS)
Iwasaki, Hideo
2014-12-01
Thermoelectric behaviors for the thermal cycles between room and high temperatures are investigated in (Bi,Sb)2Te3 and Bi2S3. Because the reliability and reproducibility of the data against repeated heating are required, the Harman method is adopted to evaluate the figure of merit, ZT, in which only electrical contacts are needed. The electrical contacts are made by the spot welding method using a simple and low-power machine made in our laboratory to avoid damage to the samples. Thermoelectric properties are changed by repeating thermal cycles, though their rate of change is not always very high and is material dependent. The carrier number dominantly contributes to the thermal hysteresis of the thermoelectric properties upon the repetition of the thermal cycles, which actually affects the sample as an annealing effect. It is pointed out that changes in thermoelectric properties upon the repetition of the thermal cycles should be examined beforehand in practical applications.
A Hysteresis Model for Piezoceramic Materials
NASA Technical Reports Server (NTRS)
Smith, Ralph C.; Ounaies, Zoubeida
1999-01-01
This paper addresses the modeling of nonlinear constitutive relations and hysteresis inherent to piezoceramic materials at moderate to high drive levels. Such models are, necessary to realize the, full potential of the materials in high performance control applications, and a necessary prerequisite is the development of techniques which permit control implementation. The approach employed here is based on the qualification of reversible and irreversible domain wall motion in response to applied electric fields. A comparison with experimental data illustrates that because the resulting ODE model is physics-based, it can be employed for both characterization and prediction of polarization levels throughout the range of actuator operation. Finally, the ODE formulation is amenable to inversion which facilitates the development of an inverse compensator for linear control design.
Connecting curves for dynamical systems
R. Gilmore; Jean-Marc Ginoux; Timothy Jones; C. Letellier; U. S. Freitas
2010-03-08
We introduce one dimensional sets to help describe and constrain the integral curves of an $n$ dimensional dynamical system. These curves provide more information about the system than the zero-dimensional sets (fixed points) do. In fact, these curves pass through the fixed points. Connecting curves are introduced using two different but equivalent definitions, one from dynamical systems theory, the other from differential geometry. We describe how to compute these curves and illustrate their properties by showing the connecting curves for a number of dynamical systems.
NASA Astrophysics Data System (ADS)
Braden, H. W.; Northover, T. P.
2010-10-01
Riemann surfaces with symmetries arise in many studies of integrable systems. We illustrate new techniques in investigating such surfaces by means of an example. By giving a homology basis well adapted to the symmetries of Klein's curve, presented as a plane curve, we derive a new expression for its period matrix. This is explicitly related to the hyperbolic model and results of Rauch and Lewittes.
Elliptic Curves David Wright Escott
Stein, William
by Hasse which shows that every elliptic curve over Fp has a rational point. The Proof of this theorem. In projective space we see that the curve is approaching the point the point (X, Y, Z) = (0, 1, 0), sinceElliptic Curves David Wright Escott May 24, 2004 Final Paper for Mathematics 129: Algebraic Number
Understanding the Hysteresis Loop Conundrum in Pharmacokinetic / Pharmacodynamic Relationships
Louizos, Christopher; Yáñez, Jaime A.; Forrest, Laird; Davies, Neal M.
2015-01-01
Hysteresis loops are phenomena that sometimes are encountered in the analysis of pharmacokinetic and pharmacodynamic relationships spanning from pre-clinical to clinical studies. When hysteresis occurs it provides insight into the complexity of drug action and disposition that can be encountered. Hysteresis loops suggest that the relationship between drug concentration and the effect being measured is not a simple direct relationship, but may have an inherent time delay and disequilibrium, which may be the result of metabolites, the consequence of changes in pharmacodynamics or the use of a non-specific assay or may involve an indirect relationship. Counter-clockwise hysteresis has been generally defined as the process in which effect can increase with time for a given drug concentration, while in the case of clockwise hysteresis the measured effect decreases with time for a given drug concentration. Hysteresis loops can occur as a consequence of a number of different pharmacokinetic and pharmacodynamic mechanisms including tolerance, distributional delay, feedback regulation, input and output rate changes, agonistic or antagonistic active metabolites, uptake into active site, slow receptor kinetics, delayed or modified activity, time-dependent protein binding and the use of racemic drugs among other factors. In this review, each of these various causes of hysteresis loops are discussed, with incorporation of relevant examples of drugs demonstrating these relationships for illustrative purposes. Furthermore, the effect that pharmaceutical formulation has on the occurrence and potential change in direction of the hysteresis loop, and the major pharmacokinetic / pharmacodynamic modeling approaches utilized to collapse and model hysteresis are detailed. PMID:24735761
Constricted hysteresis loops in Fe and Ni single crystals
NASA Astrophysics Data System (ADS)
Takahashi, Seiki; Kobayashi, Satoru; Shishido, Toetsu
2010-11-01
Magnetic hysteresis loops reflect the variety of magnetic domain structures and have been considered to have normal rectangular or leaf-like shapes in standard ferromagnets such as Fe and Ni metals. We report on observations of constricted hysteresis loops in Fe and Ni single crystals with very low defect densities. The constricted loops were observed below T=150 K and in a medium temperature range from 150 to 430 K in Fe and Ni single crystals, respectively. These constricted loops disappear by weak plastic deformation for both single crystals. The origin of constricted hysteresis loops was explained by eddy current effects under less domain wall pinning due to dislocations.
A new Preisach type hysteresis model of high temperature superconductors
NASA Astrophysics Data System (ADS)
Duan, Nana; Xu, Weijie; Wang, Shuhong; Zhu, Jianguo; Guo, Youguang
2015-05-01
This paper presents a new Preisach type hysteresis model for the high temperature superconductor. This model requires only the limiting hysteresis loop as the input data, and for this model, the limiting hysteresis loop is first separated into two limiting M-H loops based on the mechanisms, which can then be modeled by two separate modified Preisach algorithms. The area integrations of the Preisach distribution functions are determined only based on the limiting M-H loops. The validity and accuracy of this model is confirmed by comparing the simulation and experiment results of Bi-2223 and YBa2Cu3Ox superconducting tapes with external magnetic fields.
Optical bistability and hysteresis of a hybrid metal-semiconductor nanodimer
NASA Astrophysics Data System (ADS)
Malyshev, A. V.; Malyshev, V. A.
2011-07-01
Optical response of an artificial composite nanodimer comprising a semiconductor quantum dot and a metal nanosphere is analyzed theoretically. We show that internal degrees of freedom of the system can manifest bistability and optical hysteresis as functions of the incident field intensity. We argue that these effects can be observed for real-world systems, such as a CdSe quantum dot and an Au nanoparticle hybrid. These properties can be revealed by measuring the optical hysteresis of Rayleigh scattering. We also show that the total dipole moment of the system can be switched abruptly between its two stable states by small changes in the excitation intensity. The latter promises various applications in the field of all-optical processing at the nanoscale, the most basic of them being the volatile optical memory.
NASA Astrophysics Data System (ADS)
Tsytovich, Vadim; Gusein-zade, Namik; Ignatov, Alexander
2015-07-01
Dust structuring is a natural and universal process in complex plasmas. The scattering of electromagnetic waves by dust structures is governed by the factor of coherency, i.e., the total number of coherent electrons in a single structure. In the present paper, we consider how the factor of coherency changes due to additional pulse electron heating and show that it obeys a hysteresis. After the end of the pulse heating, the scattering intensity differs substantially from that before heating. There are three necessary conditions for scattering hysteresis: first, the radiation wavelength should be larger than the pattern (structure) size; second, the total number of coherent electrons confined by the structure should be large; and third, the heating pulse duration should be shorter than the characteristic time of dust structure formation. We present the results of numerical calculations using existing models of self-consistent dust structures with either positively or negatively charged dust grains. It is shown that, depending on the grain charge and the ionization rate, two types of hysteresis are possible: one with a final increase of the scattering and the other with a final decrease of the scattering. It is suggested that the hysteresis of coherent scattering can be used as a tool in laboratory experiments and that it can be a basic mechanism explaining the observed hysteresis in radar scattering by noctilucent clouds during active experiments on electron heating in mesosphere.
On the question of hysteresis in Hall magnetohydrodynamic reconnection
Sullivan, Brian P.; Bhattacharjee, A.; Huang Yimin
2010-11-15
Controversy has been raised regarding the cause of hysteresis, or bistability, of solutions to the equations that govern the geometry of the reconnection region in Hall magnetohydrodynamic (MHD) systems. This brief communication presents a comparison of the frameworks within which this controversy has arisen and illustrates that the Hall MHD hysteresis originally discovered numerically by Cassak et al. [Phys. Rev. Lett. 95, 235002 (2005)] is a different phenomenon from that recently reported by Zocco et al. [Phys. Plasmas 16, 110703 (2009)] on the basis of analysis and simulations in electron MHD with finite electron inertia. We demonstrate that the analytic prediction of hysteresis in EMHD does not describe or explain the hysteresis originally reported in Hall MHD, which is shown to persist even in the absence of electron inertia.
Could linear hysteresis contribute to shear wave losses in tissues?
Parker, Kevin J
2015-04-01
For nearly 100 y in the study of cyclical motion in materials, a particular phenomenon called "linear hysteresis" or "ideal hysteretic damping" has been widely observed. More recently in the field of shear wave elastography, the basic mechanisms underlying shear wave losses in soft tissues are in question. Could linear hysteresis play a role? An underlying theoretical question must be answered: Is there a real and causal physical model that is capable of producing linear hysteresis over a band of shear wave frequencies used in diagnostic imaging schemes? One model that can approximately produce classic linear hysteresis behavior, by examining a generalized Maxwell model with a specific power law relaxation spectrum, is described here. This provides a theoretical plausibility for the phenomenon as a candidate for models of tissue behavior. PMID:25701527
Essays on crime, hysteresis, poverty and conditional cash transfers
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 ...
Thermal hysteresis induced by ammonium polyacrylate as antifreeze polymer
NASA Astrophysics Data System (ADS)
Funakoshi, Kunio; Inada, Takaaki; Tomita, Takashi; Kawahara, Hidehisa; Miyata, Takashi
2008-07-01
Growth and melting rates of a single crystal of ice in ammonium polyacrylate (NH 4PA) aqueous solutions were measured at different solution temperatures, and the morphology of the ice crystals was observed. Thermal hysteresis, defined as the difference between the melting temperature and the non-equilibrium freezing temperature of ice, was confirmed in NH 4PA solutions at concentrations below 25.0 mM. The higher the NH 4PA concentration, the larger the thermal hysteresis, although the thermal hysteresis induced by NH 4PA was much smaller than that induced by antifreeze proteins, antifreeze glycoproteins, or poly(vinyl alcohol). A single crystal of ice grown in the NH 4PA solutions at temperatures within the thermal hysteresis region exhibited the basal faces. When the solution temperature was below the non-equilibrium freezing temperature, the ice crystal grew faster in the a-axis direction than in the c-axis direction, while retaining the basal faces.
A high-speed hysteresis motor spindle for machining applications
Bayless, Jacob D. (Jacob Daniel)
2014-01-01
An analysis of suitable drive technologies for use in a new high-speed machining spindle was performed to determine critical research areas. The focus is on a hysteresis motor topology using a solid, inherently-balanced ...
Signal characteristics of a radio-frequency hysteresis SQUID
Vasil'ev, B.
1981-09-01
The effective impedance of a RF hysteresis SQUID at the first harmonic of the eigenfrequency has been determined at the first harmonic eigenfrequency has been determined in order to describe the signal characterisics of its circuit system. (AIP).
Magnetically suspended reaction sphere with one-axis hysteresis drive
Zhou, Lei., S.M. Massachusetts Institute of Technology
2014-01-01
This thesis presents the design, modeling, implementation, and control of a magnetically suspended reaction sphere with one-axis hysteresis drive (1D-MSRS). The goal of this project is two fold: (a) exploring the design ...
Dynamic wetting on superhydrophobic surfaces: Droplet impact and wetting hysteresis
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 ...
Contact angle hysteresis: a review of fundamentals and applications
’t Mannetje, D. J. C. M.
Contact angle hysteresis is an important physical phenomenon. It is omnipresent in nature and also plays a crucial role in various industrial processes. Despite its relevance, there is a lack of consensus on how to incorporate ...
Garde, C.S.; Ray, J.; Chandra, G. )
1990-11-01
We report resistivity ({rho}) and thermopower ({ital S}) measurements between 1.7 and 300 K on CeFe{sub 2}, Ce(Fe{sub 1{minus}{ital x}}Ru{sub {ital x}}){sub 2}, Ce(Fe{sub 0.96}Al{sub 0.04}){sub 2}, and Ce(Fe{sub 0.8}Co{sub 0.2}){sub 2} alloys. At low temperatures there is an abrupt loss of ferromagnetism for these impurity-substituted alloys, indicating that CeFe{sub 2} itself exists near a magnetic instability. Below 120 K, a marked hysteresis occurs near the temperature {ital T}{sub min}, where a minimum occurs both in the {rho} and {ital S} curves, which has not been reported so far. The range of this hysteresis, {delta}, is strongly related to the temperature range over which ferromagnetic and antiferromagnetic phases overlap in these alloys.
NASA Astrophysics Data System (ADS)
Fridström, R.; Frassinetti, L.; Brunsell, P. R.
2015-10-01
The physical mechanisms behind the hysteresis in the tearing mode locking and unlocking to a resonant magnetic perturbation (RMP) are experimentally studied in EXTRAP T2R reversed-field pinch. The experiments show that the electromagnetic and the viscous torque increase with increasing perturbation amplitude until the mode locks to the wall. At the wall-locking, the plasma velocity reduction profile is peaked at the radius where the RMP is resonant. Thereafter, the viscous torque drops due to the relaxation of the velocity in the central plasma. This is the main reason for the hysteresis in the RMP locking and unlocking amplitude. The increased amplitude of the locked tearing mode produces further deepening of the hysteresis. Both experimental results are in qualitative agreement with the model in Fitzpatrick et al (2001 Phys. Plasmas 8 4489)
Modeling and characterization for polarization hysteresis of ferroelectric polymers
Bikash Shrestha; Ron Pieper; Wudyalew Wondmagegn; Nikhil Satyala
2011-01-01
We present a modeling and simulation based study for the polarization hysteresis of ferroelectric polymers. A 2- dimensional finite element device-level model was implemented using SILVACO's ATLAS device simulator to generate the polarization hysteresis characteristics for the recently reported experimental data on Au\\/Poly(vinylidene fluoride- trifluoroethylene)\\/Au metal-insulator-metal (MIM) device. The simulated polarization dependence characteristics in the P(VDF-TrFE) thin-film were predicted from
Surface free energy of a solid from contact angle hysteresis
Emil Chibowski
2003-01-01
Nature of contact angle hysteresis is discussed basing on the literature data (Colloids Surf. A 189 (2001) 265) of dynamic advancing and receding contact angles of n-alkanes and n-alcohols on a very smooth surface of 1,1,2,-trichloro-1,2,2,-trifluoroethane (FC-732) film deposited on a silicon plate. The authors considered the liquid absorption and\\/or retention (swelling) processes responsible for the observed hysteresis. In this
Saw-Tooth Acoustic Waves in Media with Hysteresis Nonlinearity
NASA Astrophysics Data System (ADS)
Nazarov, V. E.; Kiyashko, S. B.
2015-06-01
We study propagation of periodic saw-tooth waves in nondispersive media with quadratic elastic and hysteresis nonlinearity. By comparing exact solutions for saw-tooth waves and their spectral characteristics, we identified regularities in the behavior of nonlinear acoustic effects in such media. It is shown that as distinct from the case of a medium with quadratic elastic nonlinearity, the effects of nonlinear dispersion can manifest themselves in hysteresis media.
Experimental Highlight of Hysteresis Phenomenon in Rolling Contact
NASA Astrophysics Data System (ADS)
Alaci, S.; Cerlinc?, D. A.; Ciornei, F. C.; Filote, C.; Frunz?, G.
2015-02-01
In literature, the hysteresis phenomenon in rolling contacts is studied considering both rolling friction and sliding friction. Removal of sliding friction in experimental tests from a concentrated contact is a serious challenge. The paper proposes a method and presents a device ensuring pure rolling between two identical discs, normally loaded. Using photoelastic material for the two rolling discs, by means of photoelastic method, the hysteresis phenomenon due to rolling friction is qualitatively confirmed.
HYSTERESIS OF BACKFLOW IMPRINTED IN COLLIMATED JETS
Mizuta, Akira; Kino, Motoki; Nagakura, Hiroki
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.
Experiments on sorption hysteresis of desiccant materials
Pesaran, A.; Zangrando, F.
1984-08-01
Solid desiccant cooling systems take advantage of solar energy for air conditioning. The process involves passing air through a desiccant bed for drying and subsequent evaporative cooling to provide the air conditioning. The desiccant is then regenerated with hot air provided by a gas burner or solar collectors. This performance is limited by the capacity of the desiccant, its sorption properties, and the long-term stability of the desiccant material under cyclic operation conditions. Therefore, we have developed a versatile test facility to measure the sorption properties of candidate solid desiccant materials under dynamic conditions, under different geometrical configurations, and under a broad range of process air stream conditions, characteristic of desiccant dehumidifer operation. We identified a dependence of the sorption processes on air velocity and the test cell aspect ratio and the dynamic hysteresis between adsorption and desorption processes. These experiments were geared to provide data on the dynamic performance of silica gel in a parallel-passage configuration to prepare for tests with a rotary dehumidifier that will be conducted at SERI in late FY 1984. We also recommend improving the accuracy of the isotopic perturbation technique.
Hysteresis and transition in swirling nonpremixed flames
Tummers, M.J.; Huebner, A.W.; van Veen, E.H.; Hanjalic, K. [Delft University of Technology, Faculty of Applied Sciences, P.O. Box 5046, 2600 GA Delft (Netherlands); van der Meer, T.H. [University of Twente, Faculty of Engineering Technology, P.O. Box 217, 7500 AE Enschede (Netherlands)
2009-02-15
Strongly swirling nonpremixed flames are known to exhibit a hysteresis when transiting from an attached long, sooty, yellow flame to a short lifted blue flame, and vice versa. The upward transition (by increasing the air and fuel flow rates) corresponds to a vortex breakdown, i.e. an abrupt change from an attached swirling flame (unidirectional or with a weak bluff-body recirculation), to a lifted flame with a strong toroidal vortex occupying the bulk of the flame. Despite dramatic differences in their structures, mixing intensities and combustion performance, both flame types can be realised at identical flow rates, equivalence ratio and swirl intensity. We report here on comprehensive investigations of the two flame regimes at the same conditions in a well-controlled experiment in which the swirl was generated by the rotating outer pipe of the annular burner air passage. Fluid velocity measured with PIV (particle image velocimetry), the qualitative detection of reaction zones from OH PLIF (planar laser-induced fluorescence) and the temperature measured by CARS (coherent anti-Stokes Raman spectroscopy) revealed major differences in vortical structures, turbulence, mixing and reaction intensities in the two flames. We discuss the transition mechanism and arguments for the improved mixing, compact size and a broader stability range of the blue flame in comparison to the long yellow flame. (author)
Chiampi, M.; Repetto, M. [Politecnico di Torino (Italy). Dipt. di Ingegneria Elettrica Industriale] [Politecnico di Torino (Italy). Dipt. di Ingegneria Elettrica Industriale; Chiarabaglio, D. [Istituto Elettrotecnico Nazionale Galileo Ferraris, Torino (Italy)] [Istituto Elettrotecnico Nazionale Galileo Ferraris, Torino (Italy)
1995-11-01
The hysteresis phenomenon can significantly affect the behavior of magnetic cores in electrical machines and devices. This paper presents a finite element solution of periodic steady state magnetic field problems in soft materials with scalar hysteresis. The Jiles-Atherton model is employed for the generation of symmetric B-H loops and it is coupled with the Fixed Point Technique for handling magnetic nonlinearities. The proposed procedure is applied to a hysteretic model problem whose analytical solution is available. The results show that the Fixed Point Technique can efficiently deal with non-single valued material characteristics under periodic operating conditions.
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.
NASA Astrophysics Data System (ADS)
Dupeux, Guillaume; Cohen, Caroline; Le Goff, Anne; Quéré, David; Clanet, Christophe
2011-07-01
Straight lines, zigzag, parabolas (possibly truncated), circles and spirals are the main curves which can be observed in football (in the European sense, soccer elsewhere). They are, respectively, associated to heavy kick, knuckleball, lob and banana kicks. We discuss their physical origin and determine their respective domain of existence.
Soft x-ray magneto-optic Kerr rotation and element-specific hysteresis measurement
Kortright, J.B.; Rice, M.
1996-03-01
Soft x-ray magneto-optic Kerr rotation has been measured using a continuously tunable multilayer linear polarizer in the beam reflected form samples in applied magnetic fields. Like magnetic circular dichroism, Kerr rotation in the soft x-ray can be element - specific and much larger than in the visible spectral range when the photon energy is tuned near atomic core resonances. Thus sensitive element-specific hysteresis measurements are possible with this technique. Examples showing large Kerr rotation from an Fe film and element-specific hysteresis loops of the Fe and Cr in an Fe/Cr multilayer demonstrate these new capabilities. Some consequences of the strong anomalous dispersion near the FeL{sub 2,3} edges to the Kerr rotation are discussed.
Grieser, D O; Marcato, S M; Furlan, A C; Zancanela, V; Ton, A P S; Batista, E; Perine, T P; Pozza, P C; Sakomura, N K
2015-01-01
1. The objective of this study was to estimate growth parameters of carcass components (wing, thighs and drumsticks, back and breast) and organs (heart, liver, gizzard and gut) in males and females of one meat-type quail strain (Coturnix coturnix coturnix) and two laying strains (Coturnix coturnix japonica) designated either yellow or red. 2. A total of 1350 quail from 1 to 42 d old were distributed in a completely randomised design, with 5 replicates of each strain. The carcass component weights and body organs were analysed weekly and evaluated using the Gompertz function; growth rates were evaluated through derivative equations. 3. The meat-type strain presented the highest growth rates in carcass components and organs. Across strains, females showed the highest weight of internal organs at maturity compared to males. 4. Females had greater growth potential in breast, wings and back than males for both yellow and red laying quail. PMID:25490970
[Process study on hysteresis of vegetation cover influencing sand-dust events].
Xu, Xing-Kui; Wang, Xiao-Tao; Zhang, Feng
2009-02-15
Data analysis from satellite and weather stations during 1982-2000 shows nonlinear relationship between vegetation cover and sand-dust events is present in most part of China. Vegetation cover ratio in summer can impact significantly on the frequency of sand-dust storms from winter to spring in the source regions of sand-dust events. It is not quite clear about the hysteresis that vegetation cover in summer influence sand-dust events during winter and spring. A quasi-geostrophic barotropic model is used under the condition of 3 magnitude of frictional coefficient to investigate the cause of the hysteresis. Wind velocity shows a greatest decline at 90% during 72 h as initial wind velocity is 10 m/s for magnitude of frictional coefficient between atmosphere and water surface, greatest decline at 100% during 18 h for magnitude of frictional coefficient between atmosphere and bare soil and a 100% reduction of wind speed during 1 h for magnitude of frictional coefficient between atmosphere and vegetation cover. Observation and simulation prove that residual root and stem from summervegetation are one of factors to influence sand-dust events happened during winter and spring. Air inhibition from residual root and stem is a most important reason for hysteresis that vegetation cover influence sand-dust events. PMID:19402476
NASA Astrophysics Data System (ADS)
Yang, Wenjiang; Liu, Yu; Wen, Zheng; Chen, Xiaodong; Duan, Yi
2008-01-01
In order to investigate the feasible application of a permanent magnet-high-temperature superconductor (PM-HTS) interaction maglev system to a maglev train or a space vehicle launcher, we have constructed a demonstration maglev test vehicle. The force dissipation and damping of the maglev vehicle against external disturbances are studied in a wide range of amplitudes and frequencies by using a sine vibration testing set-up. The dynamic levitation force shows a typical hysteresis behavior, and the force loss is regarded as the hysteresis loss, which is believed to be due to flux motions in superconductors. In this study, we find that the hysteresis loss has weak frequency dependence at small amplitudes and that the dependence increases as the amplitude grows. To analyze the damping properties of the maglev vehicle at different field cooling (FC) conditions, we also employ a transient vibration testing technique. The maglev vehicle shows a very weak damping behavior, and the damping is almost unaffected by the trapped flux of the HTSs in different FC conditions, which is believed to be attributed to the strong pinning in melt-textured HTSs.
Briggs, Martin; Day-Lewis, Frederick D.; Ong, John B.; Harvey, Judson W.; Lane, John W.
2014-01-01
Models of dual-domain mass transfer (DDMT) are used to explain anomalous aquifer transport behavior such as the slow release of contamination and solute tracer tailing. Traditional tracer experiments to characterize DDMT are performed at the flow path scale (meters), which inherently incorporates heterogeneous exchange processes; hence, estimated “effective” parameters are sensitive to experimental design (i.e., duration and injection velocity). Recently, electrical geophysical methods have been used to aid in the inference of DDMT parameters because, unlike traditional fluid sampling, electrical methods can directly sense less-mobile solute dynamics and can target specific points along subsurface flow paths. Here we propose an analytical framework for graphical parameter inference based on a simple petrophysical model explaining the hysteretic relation between measurements of bulk and fluid conductivity arising in the presence of DDMT at the local scale. Analysis is graphical and involves visual inspection of hysteresis patterns to (1) determine the size of paired mobile and less-mobile porosities and (2) identify the exchange rate coefficient through simple curve fitting. We demonstrate the approach using laboratory column experimental data, synthetic streambed experimental data, and field tracer-test data. Results from the analytical approach compare favorably with results from calibration of numerical models and also independent measurements of mobile and less-mobile porosity. We show that localized electrical hysteresis patterns resulting from diffusive exchange are independent of injection velocity, indicating that repeatable parameters can be extracted under varied experimental designs, and these parameters represent the true intrinsic properties of specific volumes of porous media of aquifers and hyporheic zones.
Highly curved microchannel plates
NASA Technical Reports Server (NTRS)
Siegmund, O. H. W.; Cully, S.; Warren, J.; Gaines, G. A.; Priedhorsky, W.; Bloch, J.
1990-01-01
Several spherically curved microchannel plate (MCP) stack configurations were studied as part of an ongoing astrophysical detector development program, and as part of the development of the ALEXIS satellite payload. MCP pairs with surface radii of curvature as small as 7 cm, and diameters up to 46 mm have been evaluated. The experiments show that the gain (greater than 1.5 x 10 exp 7) and background characteristics (about 0.5 events/sq cm per sec) of highly curved MCP stacks are in general equivalent to the performance achieved with flat MCP stacks of similar configuration. However, gain variations across the curved MCP's due to variations in the channel length to diameter ratio are observed. The overall pulse height distribution of a highly curved surface MCP stack (greater than 50 percent FWHM) is thus broader than its flat counterpart (less than 30 percent). Preconditioning of curved MCP stacks gives comparable results to flat MCP stacks, but it also decreases the overall gain variations. Flat fields of curved MCP stacks have the same general characteristics as flat MCP stacks.
Hysteresis of ligand binding in CNGA2 ion channels
Nache, Vasilica; Eick, Thomas; Schulz, Eckhard; Schmauder, Ralf; Benndorf, Klaus
2013-01-01
Tetrameric cyclic nucleotide-gated (CNG) channels mediate receptor potentials in olfaction and vision. The channels are activated by the binding of cyclic nucleotides to a binding domain embedded in the C terminus of each subunit. Here using a fluorescent cGMP derivative (fcGMP), we show for homotetrameric CNGA2 channels that ligand unbinding is ~50 times faster at saturating than at subsaturating fcGMP. Analysis with complex Markovian models reveals two pathways for ligand unbinding; the partially liganded open channel unbinds its ligands from closed states only, whereas the fully liganded channel reaches a different open state from which it unbinds all four ligands rapidly. Consequently, the transition pathways for ligand binding and activation of a fully liganded CNGA2 channel differ from that of ligand unbinding and deactivation, resulting in pronounced hysteresis of the gating mechanism. This concentration-dependent gating mechanism allows the channels to respond to changes in the cyclic nucleotide concentration with different kinetics. PMID:24287615
Trapping and hysteresis in two-phase flow in porous media: A pore-network study
NASA Astrophysics Data System (ADS)
Joekar-Niasar, V.; Doster, F.; Armstrong, R. T.; Wildenschild, D.; Celia, M. A.
2013-07-01
Several models for two-phase flow in porous media identify trapping and connectivity of fluids as an important contribution to macroscale hysteresis. This is especially true for hysteresis in relative permeabilities. The trapping models propose trajectories from the initial saturation to the end saturation in various ways and are often based on experiments or pore-network model results for the endpoints. However, experimental data or pore-scale model results are often not available for the trajectories, that is, the fate of the connectivity of the fluids while saturation changes. Here, using a quasi static pore-network model, supported by a set of pore-scale laboratory experiments, we study how the topology of the fluids changes during drainage and imbibition including first, main and scanning curves. We find a strong hysteretic behavior in the relationship between disconnected nonwetting fluid saturation and the wetting fluid saturation in a water-wet medium. The coalescence of the invading nonwetting phase with the existing disconnected nonwetting phase depends critically on the presence (or lack thereof) of connected nonwetting phase at the beginning of the drainage process as well as on the pore geometry. This dependence involves a mechanism we refer to as "reversible corner filling." This mechanism can also be seen in laboratory experiments in volcanic tuff. The impact of these pore-network model results on existing macroscopic models is discussed.
Parameter analysis of PEM fuel cell hysteresis effects for transient load use
NASA Astrophysics Data System (ADS)
Talj, R.; Azib, T.; Béthoux, O.; Remy, G.; Marchand, C.; Berthelot, E.
2011-05-01
This paper focuses on the hysteresis effect of the polarization characteristics of a polymer electrolyte membrane fuel cell (PEMFC), mainly due to the compressor-air supply system dynamics. Indeed in PEMFC/ultracapacitor hybrid vehicles, fuel cells can be used to supply the low frequencies of the power demand only. First, the different parts of a FC system are described and modeled in order to analyze the transient stack performance decrease and to identify its main influential factors for automotive applications. Then, apart from humidity and temperature variations, each phenomenon is dynamically described, leading to a complete mathematical model based on macroscopic component parameters. Thus, an analytical model based on this set of equations enables us to draw the static voltage versus current FC characteristics. Furthermore, the hysteresis effect on the V-I curve, which still occurs during low dynamic responses, is shown while temperature and humidity are kept constant. Finally, dynamic responses of the Ballard PEMFC Nexa 1200 W generator are analyzed, and detailed experimentation and simulation are carried out for a large magnitude sinusoidal waveform at different frequencies.
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.
Padma, N; Saxena, Vibha; Sudarsan, V; Rava, Harshil; Sen, Shaswati
2014-06-01
A memory device using an organic field effect transistor (OFET) with copper phthalocyanine (CuPc) as active material was fabricated and studied. For this purpose, SiO2 dielectric surface was modified with a disordered self assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) molecule which was found to induce large disorder in CuPc film thereby generating more traps for charge carriers. Drain current-drain voltage characteristics at zero gate voltage exhibited large hysteresis which was not observed in OFET devices with ordered OTS monolayer modified and unmodified SiO2 dielectrics. The extent of hysteresis and drain current on/off ratio, reading voltage etc. were found to be dependent on the sweep rate/step voltage employed during scanning. Highest hysteresis with on/off ratio of about 240 was obtained for an optimum step voltage of 2 V while it decreased with further reduction in the same. This was attributed to the longer scanning time leading to release of trapped carriers during forward scan itself. The OFET device was found to exhibit excellent memory retention capability where OFF and ON current measured for about 2 hours after stressing the device at write and erase voltages showed good retention of on/off ratio. PMID:24738406
Hysteresis Analysis and Positioning Control for a Magnetic Shape Memory Actuator
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
Magnetic hysteresis studies of Tl-2223 substituted by Fe and Zn
NASA Astrophysics Data System (ADS)
Abou-Aly, Aly; Awad, Ramadan; Ibrahim, Ibrahim; Faraj, Ahmed
2009-03-01
Effect of Fe and Zn substitutions on the magnetic hysteresis of Tl-2223 are investigated in high magnetic fields up to 9 Tesla and at different temperatures (T= 6, 20, 40 and 80 K). The results of magnetic hysteresis loops show that the area of these loops decreases as Fe-content increases, whereas it increases for Zn-substitutions till x = 0.2 and then decreases for x > 0.2. The magnetization difference ?M is found to decay exponentially with temperature at low magnetic fields, according to ?M ? exp (-T/T0). The characteristic temperature T0 is found to be varied from 6 K to 40 K and it is related to the applied magnetic field B according to T0? B-1/n. The critical current density is calculated for the prepared samples from magnetic hysteresis measurements and compared with that determined from ac magnetic susceptibility. The results are discussed according to the flux motion and flux pinning.
NASA Astrophysics Data System (ADS)
Jahan, Ferdouse; Ballico, Mark
2007-12-01
Type R thermocouples are widely used and convenient high-temperature transfer standards; however, the achievable accuracy is limited by the effects of inhomogeneity and hysteresis. In this article, we summarize the results of the recent international comparison APMP-T-S1-04 and discuss the results of the thermoelectric scanning, spatially resolved over the length of the thermocouples. The thermoelectric signatures show both reversible (hysteresis) and irreversible inhomogeneities introduced by the calibration processes used by the participants. The results demonstrate that although the reversible hysteresis of Type R thermocouples limits their performance as a transfer standard in thermometry, this can be managed by appropriate design of the comparison protocol. By performing all calibrations from lower to higher temperatures from an initial 450°C anneal state, a pilot laboratory reproducibility of typically 0.03°C ( k = 2) and a reference value uncertainty of 0.03 0.06°C (at k = 2) over 0 1,100°C were achieved. This allowed statistically significant testing of the calibration capabilities of all the participants.
Magnetostrictive hysteresis of TbCo/CoFe multilayers and magnetic domains
NASA Astrophysics Data System (ADS)
Jay, J.-Ph.; Petit, F.; Ben Youssef, J.; Indenbom, M. V.; Thiaville, A.; Miltat, J.
2006-05-01
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 are revealed during the magnetization: big regions with opposite rotation of spontaneous magnetization vector and spontaneous magnetic domains which appear in a narrow field interval and provide an inversion of this rotation. We show that the details of the hysteresis loops of our exchange-coupled films can be described using the classical model of homogeneous magnetization rotation of single uniaxial films and the configuration of observed domains. The understanding of these features is crucial for applications (for microelectromechanical systems or microactuators) which benefit from the greatly enhanced sensitivity near the point of magnetic saturation at the transverse applied field.
Song, Jin Woo; Lee, Jang-Sub; An, Jun-Eon; Park, Chan Gook
2015-06-01
The design, fabrication, and evaluation results of a MEMS piezoresistive differential pressure sensor fabricated by the dry etching process are described in this paper. The proposed sensor is designed to have optimal performances in mid-pressure range from 0 psi to 20 psi suitable for a precision air data module. The piezoresistors with a Wheatstone bridge structure are implanted where the thermal effects are minimized subject to sustainment of the sensitivity. The rectangular-shaped silicon diaphragm is adopted and its dimension is analyzed for improving pressure sensitivity and linearity. The bridge resistors are driven by constant current to compensate temperature effects on sensitivity. The designed differential pressure sensor is fabricated by using MEMS dry etching techniques, and the fabricated sensing element is attached and packaged in a Kovar package in consideration of leakage and temperature hysteresis. The implemented sensors are tested and evaluated as well. The evaluation results show the static RSS (root sum square) accuracy including nonlinearity, non-repeatability, and pressure hysteresis before temperature compensation is about 0.09%, and the total error band which includes the RSS accuracy, the thermal hysteresis, and other thermal effects is about 0.11%, which confirm the validity of the proposed design process. PMID:26133864
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.
Magnetic hysteresis and Barkhausen noise emission analysis of magnetic materials and composites
NASA Astrophysics Data System (ADS)
Prabhu Gaunkar, Neelam
specialchapt{ABSTRACT}. Barkhausen emission studies have been used to analyze the effect of residual stresses in ferromagnetic materials. The stresses generated due to mechanical wear and tear, abrasion and prolonged use can also lead to phase changes within the material. These phase changes can cause damage to the structural parts and should be prevented. In this study we analyze the magnetic hysteresis and Barkhausen noise profile of materials with more than one ferromagnetic phase. The correlation between the hysteresis and Barkhausen noise profiles for such materials is studied. Secondary Barkhausen emission peaks can be simulated for such materials. Experimental observations are compared with simulation measurements. Drawing a correlation between the secondary emergent peaks and the composition of each secondary phase should lead to an improved technique for non-destructive characterization of ferromagnetic materials. . Improved sensor-to-specimen coupling is also essential for conducting Barkhausen noise measurements of multiphase materials which may also have different surface geometries. A finite element study was conducted to optimize the design parameters of the magnetizing core in a Barkhausen noise sensor. Several sensor parameters inclusive of core material, core-tip curvature, core length and pole spacing were studied. A procedure for developing a high sensitivity Barkhausen noise sensor by design optimization based on finite element simulations has been demonstrated. The study also shows the applicability of Barkhausen emission and magnetic hysteresis analysis as advanced tools of non-destructive characterization of ferromagnetic materials.
The hysteresis response of soil CO2 concentration and soil respiration to soil temperature
NASA Astrophysics Data System (ADS)
Zhang, Quan; Katul, Gabriel G.; Oren, Ram; Daly, Edoardo; Manzoni, Stefano; Yang, Dawen
2015-08-01
Diurnal hysteresis between soil temperature (Ts) and both CO2 concentration ([CO2]) and soil respiration rate (Rs) were reported across different field experiments. However, the causes of these hysteresis patterns remain a subject of debate, with biotic and abiotic factors both invoked as explanations. To address these issues, a CO2 gas transport model is developed by combining a layer-wise mass conservation equation for subsurface gas phase CO2, Fickian diffusion for gas transfer, and a CO2 source term that depends on soil temperature, moisture, and photosynthetic rate. Using this model, a hierarchy of numerical experiments were employed to disentangle the causes of the hysteretic [CO2]-Ts and CO2 flux Ts (i.e., F-Ts) relations. Model results show that gas transport alone can introduce both [CO2]-Ts and F-Ts hystereses and also confirm prior findings that heat flow in soils lead to [CO2] and F being out of phase with Ts, thereby providing another reason for the occurrence of both hystereses. The area (Ahys) of the [CO2]-Ts hysteresis near the surface increases, while the Ahys of the Rs-Ts hysteresis decreases as soils become wetter. Moreover, a time-lagged carbon input from photosynthesis deformed the [CO2]-Ts and Rs-Ts patterns, causing a change in the loop direction from counterclockwise to clockwise with decreasing time lag. An asymmetric 8-shaped pattern emerged as the transition state between the two loop directions. Tracing the pattern and direction of the hysteretic [CO2]-Ts and Rs-Ts relations can provide new ways to fingerprint the effects of photosynthesis stimulation on soil microbial activity and detect time lags between rhizospheric respiration and photosynthesis.
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
Jackson, P. Ryan; Sinha, Sumit; Dutta, Som; Johnson, Kevin K.; Duncker, James J.; Garcia, Marcelo H.
2013-01-01
The U.S. Geological Survey (USGS) is responsible for monitoring flows in the Chicago Sanitary and Ship Canal (CSSC) near Lemont, Illinois, as a part of the Lake Michigan Diversion Accounting overseen by the U.S. Army Corps of Engineers, Chicago District. Lake Michigan Diversion Accounting is mandated by a U.S. Supreme Court decree in order to monitor, and limit, the State of Illinois’ annual diversion of Great Lakes water through the manmade CSSC. Every 5 years, a technical review committee consisting of practicing engineers and academics reviews USGS streamgaging practices in the CSSC near Lemont, Illinois. The sixth technical review committee expressed concern that the index-velocity rating—the method used to estimate mean cross-sectional velocity from a measured index velocity—may be subject to hysteresis at this site because of the unique, unsteady hydraulics of the canal. Hysteresis in index-velocity ratings can occur at sites where the flow distribution in the channel varies significantly between the rising and falling limbs of the hydrograph for the same discharge. Presently, hysteresis in index-velocity ratings has been documented only in tidally affected sites. This report investigates whether hysteresis can occur at this nontidal site, and the conditions under which it is likely to occur, by using both a theoretical approach and a three-dimensional hydrodynamic model. The theoretical analysis investigated the conditions required for hysteresis in the index-velocity rating, and the modeling analysis focused on the effect of the timing of the inflows from the CSSC and the Cal-Sag Channel on the potential for hysteresis and whether highly resolved simulations of actual high-flow events show any evidence of hysteresis. Based on both a theoretical analysis using observed historical data and an analysis using a three-dimensional hydrodynamic model, there is no conclusive evidence for the existence of hysteresis in the index-velocity rating at the USGS streamgage on the CSSC near Lemont, Illinois. Although the theoretical analysis indicated the possibility of hysteresis at this site, the hydrodynamic conditions required to generate hysteresis are not present at this site based on historical data. Ongoing streamgaging practices at this site will use the information in this report and include periodic assessment of the index-velocity rating for any signs of hysteresis that might result from future changes to the operation of this manmade canal.
Curved Space or Curved Vacuum?
Eric V. Linder
2005-10-11
While the simple picture of a spatially flat, matter plus cosmological constant universe fits current observation of the accelerated expansion, strong consideration has also been given to models with dynamical vacuum energy. We examine the tradeoff of ``curving'' the vacuum but retaining spatial flatness, vs. curving space but retaining the cosmological constant. These different breakdowns in the simple picture could readily be distinguished by combined high accuracy supernovae and cosmic microwave background distance measurements. If we allow the uneasy situation of both breakdowns, the curvature can still be measured to 1%, but at the price of degrading estimation of the equation of state time variation by 60% or more, unless additional information (such as weak lensing data or a tight matter density prior) is included.
Qu, Minni; Li, Hui; Liu, Ran; Zhang, Shi-Li; Qiu, Zhi-Jun
2014-01-01
Hysteresis in the current-voltage characteristics is one of the major obstacles to the implementation of organic thin-film transistors in large-area integrated circuits. The hysteresis has been correlated either extrinsically to various charge-trapping/transfer mechanisms arising from gate dielectrics or surrounding ambience or intrinsically to the polaron-bipolaron reaction in low-mobility conjugated polymer thin-film transistors. However, a comprehensive understanding essential for developing viable solutions to eliminate hysteresis is yet to be established. By embedding carbon nanotubes in the polymer-based conduction channel of various lengths, here we show that the bipolaron formation/recombination combined with the H2O/O2 electrochemical reaction is responsible for the hysteresis in organic thin-film transistors. The bipolaron-induced hysteresis is a thermally activated process with an apparent activation energy of 0.29?eV for the bipolaron dissociation. This finding leads to a hysteresis model that is generally valid for thin-film transistors with both band transport and hopping conduction in semiconducting thin films. PMID:24463853
Modelling hysteresis in the transport of eroded sediment
NASA Astrophysics Data System (ADS)
Sander, Graham; Barry, D. Andrew; Zhong, Yiming; Zheng, Tingting
2013-04-01
Sediment transport hysteresis refers to the different sediment fluxes that can occur for the same discharge. For a single rainfall event, the overland flow hydrograph has rising and falling limbs, for which different hysteresis loops have been observed: (i) clockwise, (ii) anti-clockwise and (iii) figure 8 with both flow orientations. It has been suggested that the shape of these loops can be used to identify the different processes of runoff and sediment transport and the sediment source area. We present simulations carried out using the Hairsine-Rose (HR) soil erosion model that reproduce all of the above hysteresis loops for flow conditions that are straightforward to establish in a laboratory soil-erosion flume Based on the HR model, it is possible to explain the causes of the various types of hysteresis loops, in particular the role of the particle size distribution and the deposited layer of previously eroded sediment. Both of these aspects of the HR model, which are not typically included in commonly used erosion models, are crucial to produce these loops. Furthermore, we found that more involved hysteresis patterns do not depend on complicated rainfall distributions. Instead, spatial distributions of deposited sediment from a previous erosion event play a dominant role in determining the overall form and shape of the loop.
Strain dependence of pseudoelastic hysteresis of NiTi
Liu, Y.; Houver, I.; Xiang, H.; Bataillard, L.; Miyazaki, S.
1999-05-01
This work investigated the transformation-strain dependence of the stress hysteresis of pseudoelasticity associated with the stress-induced martensitic transformation in binary NiTi alloys. The strain dependence was studied with respect to the deformation mode during the stress-induced martensitic transformation, which was either localized or homogeneous. It was observed that the apparent stress hysteresis of pseudoelasticity was independent of the transformation strain within the macroscopic deformation range, for the specimens deformed in a localized manner. For specimens macroscopically deformed uniformly, the stress hysteresis of pseudoelasticity increased continuously with increasing strain from the beginning of the stress-induced martensitic transformation. The transformation-strain independence of the stress hysteresis for localized deformation is ascribed to be an artificial phenomenon, whereas the transformation-strain dependence of the hysteresis for uniform deformation is believed to be intrinsic to the process of stress-induced martensitic transformation in polycrystalline materials. This intrinsic behavior is attributed to the polycrystallinity of the materials.
NASA Astrophysics Data System (ADS)
Cihan, A.; Birkholzer, J. T.; Illangasekare, T. H.; Zhou, Q.
2013-12-01
This study presents a new theoretical model for description of hysteretic constitutive relationships between capillary pressure and saturation under capillary-dominated multiphase flow conditions in porous media. Hysteretic relationships are required for the accurate prediction of the spatial and temporal distribution of multiphase fluids in response to successively occurring drainage and imbibition events in porous media. In addition to contact angle effects, the connectivity of the void space in the porous medium plays a central role for the macroscopic manifestation of hysteresis behavior and capillary entrapment of wetting and non-wetting fluids. The hysteretic constitutive model developed in this work uses void-size distribution and a measure of connectivity of void space to compute the hysteretic curves and to predict entrapped fluid phase saturations. Two functions, the probability of drainage and the probability of wetting, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model results are verified by comparing the model predicted scanning curves with 3D pore-scale simulations as well as with actual data sets obtained from column experiments found in the literature.
NASA Astrophysics Data System (ADS)
Cihan, Abdullah; Birkholzer, Jens; Illangasekare, Tissa H.; Zhou, Quanlin
2014-01-01
This study presents a new model for description of hysteretic constitutive relationships between capillary pressure and saturation under capillary-dominated multiphase flow conditions in porous media. Hysteretic relationships are required for accurate prediction of spatial and temporal distribution of multiphase fluids in response to successively occurring drainage and imbibition events in porous media. In addition to contact angle effects, connectivity of the void space in the porous medium plays a central role for the macroscopic manifestation of hysteresis behavior and capillary entrapment of wetting and nonwetting fluids. The hysteretic constitutive model developed in this work uses void-size distribution and a measure of connectivity for void space to compute the hysteretic curves and to predict entrapped fluid-phase saturations. Two functions, the drainage connectivity function and the wetting connectivity function, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model results are verified by comparing the model predicted scanning curves with 3-D pore-scale simulations as well as with actual data sets obtained from column experiments found in the literature.
NASA Astrophysics Data System (ADS)
Biggio, Matteo; Butcher, Mark; Giustiniani, Alessandro; Masi, Alessandro; Storace, Marco
2014-02-01
In this paper we provide an experimental characterization of creep and hysteresis in a multi-layer piezoelectric actuator (PEA), taking into account their relationships in terms of memory structure. We fit the well-known log-t model to the response of the PEA when driven by piecewise-constant signals, and find that both the instantaneous and the delayed response of the PEA display hysteretic dependence on the voltage level. We investigate experimentally the dependence of the creep coefficient on the input history, by driving the PEA along first-order reversal curves and congruent minor loops, and find that it displays peculiar features like strict congruence of the minor loops and discontinuities. We finally explain the observed experimental behaviors in terms of a slow relaxation of the staircase interface line in the Preisach plane.
Morozovska, Anna N.; Morozovsky, Nicholas V. [Institute of Physics NAS of Ukraine, 46, pr. Nauki, Kyiv 03028 (Ukraine); Eliseev, Eugene A. [Institute of Problems for Material Sciences, NAS of Ukraine, 3, Krjijanovskogo str., Kyiv 03028 Ukraine (Ukraine); Varenyk, Olexandr V. [Taras Shevchenko Kyiv National University, Radiophysical Faculty 4, pr. Akademika Hlushkova, 03022 Kyiv (Ukraine); Kim, Yunseok [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Strelcov, Evgheni; Tselev, Alexander; Kalinin, Sergei V. [The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
2014-08-14
We performed self-consistent modelling of nonlinear electrotransport and electromechanical response of thin films of mixed ionic-electronic conductors (MIEC) allowing for steric effects of mobile charged defects (ions, protons, or vacancies), electron degeneration, and Vegard stresses. We establish correlations between the features of the nonlinear space-charge dynamics, current-voltage, and bending-voltage curves for different types of the film electrodes. A pronounced ferroelectric-like hysteresis of the bending-voltage loops and current maxima on the double hysteresis current-voltage loops appear for the electron-transport electrodes. The double hysteresis loop with pronounced humps indicates a memristor-type resistive switching. The switching occurs due to the strong nonlinear coupling between the electronic and ionic subsystems. A sharp meta-stable maximum of the electron density appears near one open electrode and moves to another one during the periodic change of applied voltage. Our results can explain the nonlinear nature and correlation of electrical and mechanical memory effects in thin MIEC films. The analytical expression proving that the electrically induced bending of MIEC films can be detected by interferometric methods is derived.
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.
Jonghoon Kim; Gab-Su Seo; Changyoon Chun; Bo-Hyung Cho; Seongjun Lee
2012-01-01
This work investigates the electric characteristics of a carbon-coated LiFePO4 cell with emphasis on their specific open-circuit voltage (OCV) characteristics, which include very flat OCV curves over the state-of-charge (SOC) and pronounced hysteresis phenomena. Examining discharging\\/ charging OCV measurement data of a LiFePO4\\/C cell elucidates these phenomena. A simple equivalent circuit model is newly derived and used in an OCV
Hysteresis and nonequilibrium work theorem for DNA unzipping
NASA Astrophysics Data System (ADS)
Kapri, Rajeev
2012-10-01
We study by using Monte Carlo simulations the hysteresis in unzipping and rezipping of a double stranded DNA (dsDNA) by pulling its strands in opposite directions in the fixed force ensemble. The force is increased at a constant rate from an initial value g0 to some maximum value gm that lies above the phase boundary and then decreased back again to g0. We observed hysteresis during a complete cycle of unzipping and rezipping. We obtained probability distributions of work performed over a cycle of unzipping and rezipping for various pulling rates. The mean of the distribution is found to be close (the difference being within 10%, except for very fast pulling) to the area of the hysteresis loop. We extract the equilibrium force versus separation isotherm by using the work theorem on repeated nonequilibrium force measurements. Our method is capable of reproducing the equilibrium and the nonequilibrium force-separation isotherms for the spontaneous rezipping of dsDNA.
Hysteresis Modeling in Magnetostrictive Materials Via Preisach Operators
NASA Technical Reports Server (NTRS)
Smith, R. C.
1997-01-01
A phenomenological characterization of hysteresis in magnetostrictive materials is presented. Such hysteresis is due to both the driving magnetic fields and stress relations within the material and is significant throughout, most of the drive range of magnetostrictive transducers. An accurate characterization of the hysteresis and material nonlinearities is necessary, to fully utilize the actuator/sensor capabilities of the magnetostrictive materials. Such a characterization is made here in the context of generalized Preisach operators. This yields a framework amenable to proving the well-posedness of structural models that incorporate the magnetostrictive transducers. It also provides a natural setting in which to develop practical approximation techniques. An example illustrating this framework in the context of a Timoshenko beam model is presented.
Water contact angles and hysteresis of polyamide surfaces.
Extrand, C W
2002-04-01
The wetting behavior of a series of aliphatic polyamides (PAs) has been examined. PAs with varying amide content and polyethylene (PE) were molded against glass to produce surfaces with similar roughness. After cleaning, chemical composition of the surfaces was verified with X-ray photoelectron spectroscopy. Advancing and receding contact angles were measured from small sessile water drops. Contact angles decreased with amide content while hysteresis increased. Hysteresis arose primarily from molecular interactions between the contact liquid and the solid substrates, rather than moisture absorption, variations in crystallinity, surface deformation, roughness, reorientation of amide groups, or surface contamination. Free energies of hysteresis were calculated from contact angles. For PE, which is composed entirely of nonpolar methylene groups, free energies were equivalent to the strength of dispersive van der Waals bonds. For PAs, free energies corresponded to fractional contributions from the dispersive methylene groups and polar amide groups. PMID:16290514
NASA Astrophysics Data System (ADS)
Jirsa, M.; P&; Ust, L.; Dlouhý, D.; Koblischka, M. R.
1997-02-01
The scaling and relaxation behavior around the fishtail minimum is studied in detail in a wide temperature range (3-70 K) on DyBa2Cu3O7-? single crystals exhibiting a pronounced fishtail effect. Magnetic hysteresis loops (MHL's) normalized with respect to the height and position of the fishtail maximum fall on a universal curve which form can be derived from the phenomenological model of a thermally activated flux creep proposed by Perkins et al. [Phys. Rev. B 51, 8513 (1995)]. This universal curve tends at low fields towards zero. At low temperatures, the drop of js at low fields is usually masked by a wide central peak. By subtracting the universal curve from the experimental js(B) data we separate the contribution of the central peak. It has a simple, exponentially decaying field dependence. This implies that the fishtail minimum at low fields might be understood as a result of an overlapping of two contributions originating from separate pinning mechanisms: one active mainly at high fields and dying away with B going to zero and another one (responsible for the central peak of the MHL) vanishing rapidly with increasing field. This concept is also supported by relaxation experiments. These experiments confirm that the shape of MHL's is given by a dynamic equilibrium between the induction, pinning, and relaxation processes.
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 ...
Pallandre, Antoine; Korchane, Sonia; Potier, Isabelle Le; Gamby, Jean; Lassus, Benjamin; Méance, Sebastien; Chebil, Syrine; Plecis, Adrien; Xiong, Bo; Ringard-Lefebvre, Catherine; Rosilio, Véronique; Taverna, Myriam; Haghiri-Gosnet, Anne-Marie
2015-09-22
This paper describes the measurement of the electroosmotic mobility (EOF) in a Wheatstone fluidic bridge (?FWB) as a direct probe of the surface instability. The variation of EOF known as one major contribution of the electrokinetic migration has been determined with a real-time measurement platform after different conditionings on chips. We also scan the pH of the background electrolytes with three different ionic strengths to evaluate the dependencies of the EOF as a function of the pH. A hysteresis methodology has been developed for probing the surface charge instabilities. EOF mobility has been recorded during on-a-chip electrophoresis to estimate the effect of such instability on the analytical performance. As expected, our experimental curves show that a decrease in the ionic strength increases the surface charge stability of the hybrid microchip. This result demonstrates that ionic exchanges between the surface and the fluid are clearly involved in the stability of the surface charge. With this original method based on real-time EOF measurement, the surface state can be characterized after hydrodynamic and electrophoresis sequences to mimic any liquid conditioning and separation steps. Finally, as a demonstrative application, isotherms of the adsorption of insulin have been recorded showing the change in surface charge by unspecific adsorption of this biomolecule onto the microfluidic channel's wall. These methodologies and findings could be particularly relevant to investigating various analytical pathways and to understanding the molecular mechanisms at solid/liquid interfaces. PMID:26317498
Renka, Robert
value. Only the parametric form extends to space curves. All three forms extend to surfaces of degree less than or equal to n - 1. This is an n-dimensional linear space. proof: We first showCurve Fitting R. J. Renka Department of Computer Science & Engineering University of North Texas 11
Suspended-sediment rating curve response to urbanization and wildfire, Santa Ana River, California
Warrick, J.A.; Rubin, D.M.
2007-01-01
River suspended-sediment concentrations provide insights to the erosion and transport of materials from a landscape, and changes in concentrations with time may result from landscape processes or human disturbance. Here we show that suspended-sediment concentrations in the Santa Ana River, California, decreased 20-fold with respect to discharge during a 34-year period (1968?2001). These decreases cannot be attributed to changes in sampling technique or timing, nor to event or seasonal hysteresis. Annual peak and total discharge, however, reveal sixfold increases over the 34-year record, which largely explain the decreases in sediment concentration by a nonlinear dilution process. The hydrological changes were related to the widespread urbanization of the watershed, which resulted in increases in storm water discharge without detectable alteration of sediment discharge, thus reducing suspended-sediment concentrations. Periodic upland wildfire significantly increased water discharge, sediment discharge, and suspended-sediment concentrations and thus further altered the rating curve with time. Our results suggest that previous inventories of southern California sediment flux, which assume time-constant rating curves and extend these curves beyond the sampling history, may have substantially overestimated loads during the most recent decades.
A compensation method for the hysteresis error of DVD VCM
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
Efficient Inverse Compensation for Hysteresis Via Homogenized Energy Models
a model of the material as part of a nonlinear control. 4. Model the material and invert this modelEfficient Inverse Compensation for Hysteresis Via Homogenized Energy Models Thomas R. Braun and Ralph C. Smith Center for Research in Scientific Computation Department of Mathematics North Carolina
A Differential Model of Adsorption Hysteresis with Applications to Chromatography
Peszynska, Malgorzata
A Differential Model of Adsorption Hysteresis with Applications to Chromatography M. Peszy- ena occuring in chromatography or other related disciplines, see [21]. These models have the general rise in the beginning of 20th century, chromatography has become a wide industrial domain delivering
Influence of interfacial dislocations on hysteresis loops of ferroelectric films
Chen, Long-Qing
field, which describes the switching behavior of spontaneous polarization.1 It directly affects bearing on the control and optimization of the switching behavior of ferroelectric films for applications hysteresis loop including the remanent polarization and coercive field using phase-field simulations. We
Hysteresis modelling of a core-free EAP tubular actuator
NASA Astrophysics Data System (ADS)
Sarban, Rahimullah; Oubaek, Jakob; Kristjánsdóttir, Gisla R.; Jones, Richard W.
2009-03-01
This work investigates the characterization and modelling of hysteresis in a core-free dielectric electro-active polymer (EAP) tubular actuator. The overall hysteresis effect of the voltage driven system comprises the inherent hysteresis of the fabricated tubular actuator plus a time lag introduced by the associated power supply when charging and discharging the actuator. Specifically the dynamic asymmetric hysteretic model of the voltage driven tubular actuator is decomposed into two models in series, comprising the nonlinear static voltage-strain characteristic of the actuator and an approximate symmetric hysteretic characteristic. The Bouc-Wen model approach is popular in engineering because of its simple interpretation as a nonlinear black-box model, the relatively low number of parameters needed to describe it, and the availability of both optimization and least squares estimation approaches to identify model parameters from experimental data. A disadvantage of the Bouc-Wen modelling approach is that it cannot accurately model asymmetric hysteresis behaviour. The use of the decomposition approach allows the Bouc-Wen model to be used to describe the approximate symmetric hysteretic characteristic. The model parameters are identified using an evolutionary computational algorithm - particle swarm optimization (PSO). PSO is an evolutionary based optimization approach that has been shown to be superior to genetic algorithms.
A Model for Asymmetric Hysteresis in Piezoceramic Materials
A Model for Asymmetric Hysteresis in Piezoceramic Materials Ralph C. Smith Center for Research by piezoelectric materials at moderate to high field levels. For soft materials in which dipoles are easily polarization point and symmetric models can be employed. In harder materials, however, the loops are no longer
Dynamics of non-isothermal martensitic phase transitions and hysteresis
Vainchtein, Anna
. Keywords: Phase transitions; Pseudoelastic hysteresis; Latent heat; Heat conduction; Thermoviscoelasticity by these materials is called pseudoelasticity and refers to the ability of the material in a certain temperature correction. The underlying mechanism for pseudoelasticity is the trans- formation, induced by the loading
A dead-beat adaptive hysteresis current control
Simone Buso; Sandro Fasolo; Luigi Malesani; Paolo Mattavelli
2000-01-01
This paper proposes a new digital algorithm for the implementation of the fixed-frequency adaptive hysteresis current control for voltage-source inverters. The key features of the new algorithm are the minimization of the analog external circuitry, the capability to automatically compensate for the inverter deadtime effects without appreciable delay and a tight synchronization of the inverter voltage pulses with an external
Perovskite-fullerene hybrid materials suppress hysteresis in planar diodes.
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
Small hysteresis and high energy storage power of antiferroelectric ceramics
NASA Astrophysics Data System (ADS)
Wang, Jinfei; Yang, Tongqing; Chen, Shengchen; Yao, Xi
2014-09-01
In this paper, modified Pb(Zr,Ti)O3(PZT) antiferroelectric (AFE) ceramics system was investigated by traditional solid state method. It was observed that the effect of different contents of Zr/Sn, Zr/Ti on modified PZT antiferroelectrics. With increasing Zr/Sn content, the EAFE (electric field of AFE phase to ferroelectric (FE) phase) value was enlarged. The phase switch field was reduced from FE to AFE (EFA). The hysteresis loops were changed from "slanted" to "square"-types. With increasing Zr/Ti concentrate, the EAFE value, and also the EFA was enlarged, while the hysteresis switch ?E was reduced. The hysteresis loops was from "square" to "slanted"-types. The samples with square hysteresis loops are suitable for energy storage capacitor applications, the composition of ceramics was Pb0.97La0.02(Zr0.90Sn0.05Ti0.05)O3, which have the largest energy storage density 4.426J/cm3 at 227 kV/cm, and ?E was 80 kV/cm, energy efficient ? was about 0.612.
Sensor Saturation for Hysteresis Reduction in GMR Magnetometers
Krchnavek, Robert R.
. Krchnavek Electrical & Computer Engineering Rowan University Glassboro, New Jersey 080281700 Email: mease fields, are relatively sensitive, can be fabricated to measure over a large range of field strengths is that the output is a function of the history of the magnetic fields that have been on the device, i.e., hysteresis
Intrinsic Hysteresis Loops Calculation of BZT Thin Films
NASA Astrophysics Data System (ADS)
Hikam, M.; Adnan, S. R.
2014-04-01
The Landau Devonshire (LK) simulation is utilized to calculate the intrinsic hysteresis properties of Barium Zirconium Titanate (BZT) doped by Indium and Lanthanum. A Delphi program run on Windows platform is used to facilitate the calculation. The simulation is very useful to calculate and understand the Gibbs free energy and the relationship between spontaneous polarization and electric field.
Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume.
Abe-Ouchi, Ayako; Saito, Fuyuki; Kawamura, Kenji; Raymo, Maureen E; Okuno, Jun'ichi; Takahashi, Kunio; Blatter, Heinz
2013-08-01
The growth and reduction of Northern Hemisphere ice sheets over the past million years is dominated by an approximately 100,000-year periodicity and a sawtooth pattern (gradual growth and fast termination). Milankovitch theory proposes that summer insolation at high northern latitudes drives the glacial cycles, and statistical tests have demonstrated that the glacial cycles are indeed linked to eccentricity, obliquity and precession cycles. Yet insolation alone cannot explain the strong 100,000-year cycle, suggesting that internal climatic feedbacks may also be at work. Earlier conceptual models, for example, showed that glacial terminations are associated with the build-up of Northern Hemisphere 'excess ice', but the physical mechanisms underpinning the 100,000-year cycle remain unclear. Here we show, using comprehensive climate and ice-sheet models, that insolation and internal feedbacks between the climate, the ice sheets and the lithosphere-asthenosphere system explain the 100,000-year periodicity. The responses of equilibrium states of ice sheets to summer insolation show hysteresis, with the shape and position of the hysteresis loop playing a key part in determining the periodicities of glacial cycles. The hysteresis loop of the North American ice sheet is such that after inception of the ice sheet, its mass balance remains mostly positive through several precession cycles, whose amplitudes decrease towards an eccentricity minimum. The larger the ice sheet grows and extends towards lower latitudes, the smaller is the insolation required to make the mass balance negative. Therefore, once a large ice sheet is established, a moderate increase in insolation is sufficient to trigger a negative mass balance, leading to an almost complete retreat of the ice sheet within several thousand years. This fast retreat is governed mainly by rapid ablation due to the lowered surface elevation resulting from delayed isostatic rebound, which is the lithosphere-asthenosphere response. Carbon dioxide is involved, but is not determinative, in the evolution of the 100,000-year glacial cycles. PMID:23925242
The e ect of additive noise on dynamical hysteresis Nils Berglund and Barbara Gentz
for small and large driving amplitude. Above this threshold, the area of typical hysteresis cycles depends). Keywords and phrases. dynamical systems, singular perturbations, hysteresis cycles, scaling laws, non-autonomous of hysteresis cycles was shown to obey the scaling law A ' A 0 + " 2=3 (1.2) for suÃ?ciently large driving
Chun-Yi Su; Qingqing Wang; Xinkai Chen; Subhash Rakheja
2005-01-01
Control of nonlinear systems preceded by unknown hysteresis nonlinearities is a challenging task and has received increasing attention in recent years due to growing industrial demands involving varied applications. In the literature, many mathematical models have been proposed to describe the hysteresis nonlinearities. The challenge addressed here is how to fuse those hysteresis models with available robust control techniques to
Hysteresis compensation for smart actuators using inverse generalized Prandtl-Ishlinskii model
Mohammad Al Janaideh; Ying Feng; Subhash Rakheja; Chun-Yi Su; Camille Alain Rabbath
2009-01-01
Control of smart actuators is limited due to strong hysteresis effects which affect the accuracy of these actuators in micropositioning applications. In this paper, generalized Prandtl-Ishlinskii hysteresis model and its inverse are presented to characterize and to compensate hysteresis effects in smart actuators, where a generalized symmetric play operator is adopted to form the generalized Prandtl-Ishlinskii model. The capability of
On the control of nonlinear systems with unknown Prandtl-Ishlinskii hysteresis
Chun-Yi Su; Qingqing Wang; Xinkai Chen; Subhash Rakheja
2005-01-01
Control of nonlinear systems preceded by unknown hysteresis nonlinearities is a challenging task and has received great attention recently due to increasing industrial demands. In the literature, many mathematical models have been proposed to describe the hysteresis. The challenge addressed here is how to fuse those hysteresis models with available robust control techniques to have the basic requirement of stability
Unconventional Magnetic and Resistive Hysteresis in an Iodine-Bonded Molecular Conductor.
Kawaguchi, Genta; Maesato, Mitsuhiko; Komatsu, Tokutaro; Kitagawa, Hiroshi; Imakubo, Tatsuro; Kiswandhi, Andhika; Graf, David; Brooks, James S
2015-08-24
Simultaneous manipulation of both spin and charge is a crucial issue in magnetic conductors. We report on a strong correlation between magnetism and conductivity in the iodine-bonded molecular conductor (DIETSe)2 FeBr2 Cl2 [DIETSe=diiodo(ethylenedithio)tetraselenafulvalene], which is the first molecular conductor showing a large hysteresis in both magnetic moment and magnetoresistance associated with a spin-flop transition. Utilizing a mixed-anion approach and iodine bonding interactions, we tailored a molecular conductor with random exchange interactions exhibiting unforeseen physical properties. PMID:26179678
Droplets on Inclined Plates: Local and Global Hysteresis of Pinned Capillary Surfaces
NASA Astrophysics Data System (ADS)
Musterd, Michiel; van Steijn, Volkert; Kleijn, Chris R.; Kreutzer, Michiel T.
2014-08-01
Local contact line pinning prevents droplets from rearranging to minimal global energy, and models for droplets without pinning cannot predict their shape. We show that experiments are much better described by a theory, developed herein, that does account for the constrained contact line motion, using as an example droplets on tilted plates. We map out their shapes in suitable phase spaces. For 2D droplets, the critical point of maximum tilt depends on the hysteresis range and Bond number. In 3D, it also depends on the initial width, highlighting the importance of the deposition history.
Phase transitions, hysteresis, and hyperbolicity for self-organized alignment dynamics
Pierre Degond; Amic Frouvelle; Jian-Guo Liu
2014-09-25
We provide a complete and rigorous description of phase transitions for kinetic models of self-propelled particles interacting through alignment. These models exhibit a competition between alignment and noise. Both the alignment frequency and noise intensity depend on a measure of the local alignment. We show that, in the spatially homogeneous case, the phase transition features (number and nature of equilibria, stability, convergence rate, phase diagram, hysteresis) are totally encoded in how the ratio between the alignment and noise intensities depend on the local alignment. In the spatially inhomogeneous case, we derive the macroscopic models associated to the stable equilibria and classify their hyperbolicity according to the same function.
Phase Transitions, Hysteresis, and Hyperbolicity for Self-Organized Alignment Dynamics
NASA Astrophysics Data System (ADS)
Degond, Pierre; Frouvelle, Amic; Liu, Jian-Guo
2015-04-01
We provide a complete and rigorous description of phase transitions for kinetic models of self-propelled particles interacting through alignment. These models exhibit a competition between alignment and noise. Both the alignment frequency and noise intensity depend on a measure of the local alignment. We show that, in the spatially homogeneous case, the phase transition features (number and nature of equilibria, stability, convergence rate, phase diagram, hysteresis) are totally encoded in how the ratio between the alignment and noise intensities depend on the local alignment. In the spatially inhomogeneous case, we derive the macroscopic models associated to the stable equilibria and classify their hyperbolicity according to the same function.
Hysteresis in suspended sediment to turbidity relations due to changing particle size distributions
Landers, Mark N.; Sturm, Terry W.
2013-01-01
Turbidity (T) is the most ubiquitous of surrogate technologies used to estimate suspended-sediment concentration (SSC). The effects of sediment size on turbidity are well documented; however, effects from changes in particle size distributions (PSD) are rarely evaluated. Hysteresis in relations of SSC-to-turbidity (SSC~T) for single stormflow events was observed and quantified for a data set of 195 concurrent measurements of SSC, turbidity, discharge, velocity, and volumetric PSD collected during five stormflows in 2009–2010 on Yellow River at Gees Mill Road in metropolitan Atlanta, Georgia. Regressions of SSC-normalized turbidity (T/SSC) on concurrently measured PSD percentiles show an inverse, exponential influence of particle size on turbidity that is not constant across the size range of the PSD. The majority of the influence of PSD on T/SSC is from particles of fine-silt and smaller sizes (finer than 16 microns). This study shows that small changes in the often assumed stability of the PSD are significant to SSC~T relations. Changes of only 5 microns in the fine silt and smaller size fractions of suspended sediment PSD can produce hysteresis in the SSC~T rating that can increase error and produce bias. Observed SSC~T hysteresis may be an indicator of changes in sediment properties during stormflows and of potential changes in sediment sources. Trends in the PSD time series indicate that sediment transport is capacity-limited for sand-sized sediment in the channel and supply-limited for fine silt and smaller sediment from the hillslope.
NASA Astrophysics Data System (ADS)
Maurya, Arvind; Thamizhavel, A.; Dhar, S. K.; Bonville, P.
2015-07-01
We present detailed investigations on single crystals of quaternary EuRhAl4Si2 and EuIrAl4Si2. The two compounds order antiferromagnetically at TN1?=?11.7 and 14.7?K, respectively, each undergoing two magnetic transitions. The magnetic properties in the ordered state present a large anisotropy despite Eu2+being an S-state ion for which the single-ion anisotropy is expected to be weak. Two features in the magnetization measured along the c-axis are prominent. At 1.8?K, a ferromagnetic-like jump occurs at very low field to a value one third of the saturation magnetization (1/3?M0) followed by a wide plateau up to 2 T for Rh and 4 T for Ir-compound. At this field value, a sharp hysteretic spin-flop transition occurs to a fully saturated state (M0). Surprisingly, the magnetization does not return to origin when the field is reduced to zero in the return cycle, as expected in an antiferromagnet. Instead, a remnant magnetization 1/3 M0 is observed and the magnetic loop around the origin shows hysteresis. This suggests that the zero field magnetic structure has a ferromagnetic component, and we present a model with up to third neighbor exchange and dipolar interaction which reproduces the magnetization curves and hints to an “up-up-down” magnetic structure in zero field.
Maurya, Arvind; Thamizhavel, A; Dhar, S K; Bonville, P
2015-01-01
We present detailed investigations on single crystals of quaternary EuRhAl4Si2 and EuIrAl4Si2. The two compounds order antiferromagnetically at TN1?=?11.7 and 14.7?K, respectively, each undergoing two magnetic transitions. The magnetic properties in the ordered state present a large anisotropy despite Eu(2+)being an S-state ion for which the single-ion anisotropy is expected to be weak. Two features in the magnetization measured along the c-axis are prominent. At 1.8?K, a ferromagnetic-like jump occurs at very low field to a value one third of the saturation magnetization (1/3?M0) followed by a wide plateau up to 2 T for Rh and 4 T for Ir-compound. At this field value, a sharp hysteretic spin-flop transition occurs to a fully saturated state (M0). Surprisingly, the magnetization does not return to origin when the field is reduced to zero in the return cycle, as expected in an antiferromagnet. Instead, a remnant magnetization 1/3 M0 is observed and the magnetic loop around the origin shows hysteresis. This suggests that the zero field magnetic structure has a ferromagnetic component, and we present a model with up to third neighbor exchange and dipolar interaction which reproduces the magnetization curves and hints to an "up-up-down" magnetic structure in zero field. PMID:26156410
Maurya, Arvind; Thamizhavel, A.; Dhar, S. K.; Bonville, P.
2015-01-01
We present detailed investigations on single crystals of quaternary EuRhAl4Si2 and EuIrAl4Si2. The two compounds order antiferromagnetically at TN1?=?11.7 and 14.7?K, respectively, each undergoing two magnetic transitions. The magnetic properties in the ordered state present a large anisotropy despite Eu2+being an S-state ion for which the single-ion anisotropy is expected to be weak. Two features in the magnetization measured along the c-axis are prominent. At 1.8?K, a ferromagnetic-like jump occurs at very low field to a value one third of the saturation magnetization (1/3?M0) followed by a wide plateau up to 2 T for Rh and 4 T for Ir-compound. At this field value, a sharp hysteretic spin-flop transition occurs to a fully saturated state (M0). Surprisingly, the magnetization does not return to origin when the field is reduced to zero in the return cycle, as expected in an antiferromagnet. Instead, a remnant magnetization 1/3 M0 is observed and the magnetic loop around the origin shows hysteresis. This suggests that the zero field magnetic structure has a ferromagnetic component, and we present a model with up to third neighbor exchange and dipolar interaction which reproduces the magnetization curves and hints to an “up-up-down” magnetic structure in zero field. PMID:26156410
Analysis of Magnetic Minor Hysteresis Loops in Thermally Aged and Cold-rolled Fe-Cu Alloys
NASA Astrophysics Data System (ADS)
Takahashi, F.; Kobayashi, S.; Murakami, T.; Takahashi, S.; Kamada, Y.; Kikuchi, H.
2011-01-01
Neutron irradiation causes the formation of Cu precipitate in reactor pressure vessel steel and makes the steel susceptible to rupture. In the present study, we have examined magnetic minor hysteresis loops of Fe-1wt%Cu alloy after thermally ageing at 753 K and subsequent cold rolling to elucidate the effects of Cu precipitation on magnetic properties. Minor-loop coefficients, obtained from scaling power laws between field-dependent parameters of minor hysteresis loops, decrease with ageing time and show a local maximum around 200 min, reflecting the growth of Cu precipitates with ageing. For the alloy cold-rolled after ageing, the minor-loop properties linearly increase with reduction and show a good relationship with mechanical properties such as DBTT and hardness. These observations indicate that the analysis method using magnetic minor loops can be an useful technique of nondestructive evaluation of irradiation embrittlement and subsequent deformation hardening in reactor pressure vessel steels.
NASA Astrophysics Data System (ADS)
Gattacceca, J.; Suavet, C.; Rochette, P.; Weiss, B. P.; Winklhofer, M.; Uehara, M.; Friedrich, Jon M.
2014-04-01
Magnetic properties are sensitive proxies to characterize FeNi metal phases in meteorites. We present a data set of magnetic hysteresis properties of 91 ordinary chondrite falls. We show that hysteresis properties are distinctive of individual meteorites while homogeneous among meteorite subsamples. Except for the most primitive chondrites, these properties can be explained by a mixture of multidomain kamacite that dominates the induced magnetism and tetrataenite (both in the cloudy zone as single-domain grains, and as larger multidomain grains in plessite and in the rim of zoned taenite) dominates the remanent magnetism, in agreement with previous microscopic magnetic observations. The bulk metal contents derived from magnetic measurements are in agreement with those estimated previously from chemical analyses. We evidence a decreasing metal content with increasing petrologic type in ordinary chondrites, compatible with oxidation of metal during thermal metamorphism. Types 5 and 6 ordinary chondrites have higher tetrataenite content than type 4 chondrites. This is compatible with lower cooling rates in the 650-450 °C interval for higher petrographic types (consistent with an onion-shell model), but is more likely the result of the oxidation of ordinary chondrites with increasing metamorphism. In equilibrated chondrites, shock-related transient heating events above approximately 500 °C result in the disordering of tetrataenite and associated drastic change in magnetic properties. As a good indicator of the amount of tetrataenite, hysteresis properties are a very sensitive proxy of the thermal history of ordinary chondrites, revealing low cooling rates during thermal metamorphism and high cooling rates (e.g., following shock reheating or excavation after thermal metamorphism). Our data strengthen the view that the poor magnetic recording properties of multidomain kamacite and the secondary origin of tetrataenite make equilibrated ordinary chondrites challenging targets for paleomagnetic study.
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.
NASA Astrophysics Data System (ADS)
Xiulin, Y.; Hongji, X.; Yuweng, Z.; Hongzhang, Q.
According to heat and mass transfer mechanism in porous layers, the knowledge of nucleate pool boiling from sintered porous surfaces is reported. The boiling heat transfer coefficient of porous surfaces is enhanced approximately 3-10 times that of smooth surfaces. Through experiment, we obtained results showing that the distance between two tubes makes impact on boiling heat transfer of porous surfaces. We observed that there is a hysteresis phenomenon when porous surfaces are submerged in liquid nitrogen.
The marine biodiversity curve is an icon of paleobiology. The familiar curve shows
Waxman, David
in the flush of new insight from Sepkoski's database. Today, a new generation of Chicago paleontologists has the temperate phage infects Escherichia coli, it enters one of two pathways: lytic (replicates and kills
Clapeyron slope reversal in the melting curve of AuGa2 at 5.5 GPa
NASA Astrophysics Data System (ADS)
Geballe, Z. M.; Raju, S. V.; Godwal, B. K.; Jeanloz, R.
2013-10-01
We use x-ray diffraction in a resistively heated diamond anvil cell to extend the melting curve of AuGa2 beyond its minimum at 5.5 GPa and 720 K, and to constrain the high-temperature phase boundaries between cubic (fluorite structure), orthorhombic (cottunite structure) and monoclinic phases. We document a large change in Clapeyron slope that coincides with the transitions from cubic to lower symmetry phases, showing that a structural transition is the direct cause of the change in slope. In addition, moderate (?30 K) to large (90 K) hysteresis is detected between melting and freezing, from which we infer that at high pressures, AuGa2 crystals can remain in a metastable state at more than 5% above the thermodynamic melting temperature.
A suite of user-friendly global climate models: Hysteresis experiments
NASA Astrophysics Data System (ADS)
Fraedrich, K.
2012-05-01
A hierarchy of global spectral circulation models is introduced ranging from the shallow-water system via the primitive-equation dynamical core of the atmosphere to the Planet Simulator as a Global Climate Model (GCM) of Intermediate Complexity (MIC) which can be used to run climate and paleo-climate simulations for time scales up to ten thousand years or more in an acceptable real time. The priorities in development are set to speed, easy handling and portability with a modular structure suitable for problem-dependent configuration. Adaptions exist for the planetary atmospheres of Mars and of Saturn's moon Titan and are being extended. Common coupling interfaces enable the addition of ocean, ice, vegetation models and more. An interactive mode with a Model Starter and a Graphical User Interface (GUI) is available to select a configuration from the available model suite, to set its parameters and inspect atmospheric fields while changing the models' parameters on the fly. This is especially useful for teaching, debugging and tuning of parameterizations. An updated overview of the model suite's features is presented based on the Earth-like climate model Planet Simulator with mixed-layer ocean introducing static and memory hysteresis in terms of a parameter sweep of the solar constant and CO2 concentrations. The static hysteresis experiment demonstrates that the solar constant varying by 20% reveals warm and snowball Earth climate regimes depending on the history of the system. This hysteresis subjected to a thermodynamic analysis shows the following features: i) Both climate regimes are characterized by global mean surface temperature and entropy growing with increasing solar constant. ii) The climate system's efficiency decreases (increases) with increasing solar constant in present-day warm (snowball) climate conditions. iii) Climate transitions near bifurcation points are characterized by high efficiency associated with the system's large distance from the stable regime. Memory hysteresis evolves when changing the direct atmospheric radiative forcing which, associated with a well-mixed CO2 concentration, modifies the planetary thermodynamic state, and hence the surface temperature. The hysteresis effected by different CO2 change rates is analysed: i) The response is due to infrared cooling (for constant temperature lapse-rate) which, in turn, is related to the surface temperature through the Stefan-Boltzmann law in a ratio proportional to the new infrared opacity. Subsequent indirect effects, that are water-vapour-greenhouse and ice-albedo feedbacks, enhance the response. ii) Different rates of CO2 variation may lead to similar transient climates characterized by the same global mean surface temperature but different values of CO2 concentration. iii) Far from the bifurcation points, the model's climate depends on the history of the radiative forcing thus displaying a hysteresis cycle that is neither static nor dynamical, but is related to the memory response of the model determined by the mixed-layer depth of the ocean. Results are supported by a zero-dimensional energy balance model.
Hysteresis in the surfactant-induced volume transition of hydrogels.
Gernandt, Jonas; Hansson, Per
2015-01-29
The discontinuous uptake and release of surfactants by hydrogels and the accompanying discontinuous volume transition is known to occur with a hysteresis. We have performed a theoretical analysis in order to find the mechanistic origin of this phenomenon. Using a mean-field model, we have quantitatively reproduced the experimental behavior by considering the cost of elastically deforming the gel material to allow phase coexistence. The major part of the hysteresis is due to the high phase coexistence cost of the swelling transition, since in this direction the coexistence cost depends not only on the elasticity of the network (being a weak force in comparison) but also on the entropy of the monovalent nonsurfactant electrolyte present in the system. PMID:25567724
Efficiency of hysteresis rods in small spacecraft attitude stabilization.
Farrahi, Assal; Sanz-Andrés, Ángel
2013-01-01
A semiempirical method for predicting the damping efficiency of hysteresis rods on-board small satellites is presented. It is based on the evaluation of dissipating energy variation of different ferromagnetic materials for two different rod shapes: thin film and circular cross-section rods, as a function of their elongation. Based on this formulation, an optimum design considering the size of hysteresis rods, their cross section shape, and layout has been proposed. Finally, the formulation developed was applied to the case of four existing small satellites, whose corresponding in-flight data are published. A good agreement between the estimated rotational speed decay time and the in-flight data has been observed. PMID:24501579
Efficiency of Hysteresis Rods in Small Spacecraft Attitude Stabilization
Farrahi, Assal; Sanz-Andrés, Ángel
2013-01-01
A semiempirical method for predicting the damping efficiency of hysteresis rods on-board small satellites is presented. It is based on the evaluation of dissipating energy variation of different ferromagnetic materials for two different rod shapes: thin film and circular cross-section rods, as a function of their elongation. Based on this formulation, an optimum design considering the size of hysteresis rods, their cross section shape, and layout has been proposed. Finally, the formulation developed was applied to the case of four existing small satellites, whose corresponding in-flight data are published. A good agreement between the estimated rotational speed decay time and the in-flight data has been observed. PMID:24501579
Hysteresis and Kinetic Effects During Liquid-Solid Transitions
Streitz, F H; Chau, R
2009-02-17
We address the fundamental issue of phase transition kinetics in dynamically compressed materials. Focusing on solid bismuth (Bi) as a prototype material, we used a variety of time-resolved experiments including electrical conductivity and velocimetry to study the phase transition kinetics of the solid-solid phase transitions. Simple single shock experiments performed on several low-lying high pressure phases of Bi, revealed surprisingly complex behavior and slow dynamics. Strong hysteresis effects were observed in the transition behavior in experiments where the compressed Bi was allowed to release back across a phase line. These experiments represent the first reported simultaneous use of resistivity and velocimetry in a shock compression experiment, and the first observation of hysteresis effects occurring during dynamic compression and release.
Influence of impurities on dynamic hysteresis of magnetization reversal
NASA Astrophysics Data System (ADS)
Zheng, Guang-Ping; Li, Mo
2002-08-01
The effects of impurities on driving-rate-dependent energy loss in ferromagnets are investigated by analyzing several well-defined models for magnetization reversal. The random-field Ising models are analyzed using a mean-field approximation and Monte Carlo simulation. The hysteresis loop area A is found to obey a universal scaling relation with respect to the linear driving rates h of the applied field, A-A0~h?. The scaling exponent ? is found independent of the disorder strength D. In a random-field spherical model, the energy loss increases as a power law with the driving rate A~h?(D). The scaling exponent ?(D) increases with increasing D. These results indicate that the scaling and universality for the field-driven first-order phase transition can be understood in the framework of dynamic hysteresis.
VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY
Bradley, David
VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY 1.Introduction Students tend to regard the elongated "S-shaped" [3, 6, 8] logistic curve here is to show how the logistic curve may be derived more directly as a simple consequence of the more
VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY
Bradley, David
VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY 1. Introduction Students tend to regard the elongated "S-shaped" [3, 6, 8] logistic curve of pop- ulation dynamics (fig. 1) as somewhat exotic. It is typically, 8, 9, 10, 11]. My purpose here is to show how the logistic curve may be derived more directly
VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY
Bradley, David
VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY 1. Introduction Students tend to regard the elongated ``Sshaped'' [3, 6, 8] logistic curve of pop ulation dynamics (fig. 1) as somewhat exotic, 5, 6, 7, 8, 9, 10, 11]. My purpose here is to show how the logistic curve may be derived more
NASA Astrophysics Data System (ADS)
Yamamoto, Toshihiro; Nakajima, Yoshiki; Takei, Tatsuya; Fujisaki, Yoshihide; Fukagawa, Hirohiko; Suzuki, Mitsunori; Motomura, Genichi; Sato, Hiroto; Tokito, Shizuo; Fujikake, Hideo
2011-02-01
A new driving scheme for an active-matrix organic light emitting diode (AMOLED) display was developed to prevent the picture quality degradation caused by the hysteresis characteristics of organic thin film transistors (OTFTs). In this driving scheme, the gate electrode voltage of a driving-OTFT is directly controlled through the storage capacitor so that the operating point for the driving-OTFT is on the same hysteresis curve for every pixel after signal data are stored in the storage capacitor. Although the number of OTFTs in each pixel for the AMOLED display is restricted because OTFT size should be large enough to drive organic light emitting diodes (OLEDs) due to their small carrier mobility, it can improve the picture quality for an OTFT-driven flexible OLED display with the basic two transistor-one capacitor circuitry.
Barkhausen discontinuities and hysteresis of ferromagnetics: New stochastic approach
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.
Automatic system for determination of dielectric hysteresis loop parameters
NASA Astrophysics Data System (ADS)
Proszak, Wladyslaw
2006-10-01
Research works were focused on design and implementation of based on Sawyer-Tower measurement set, computer system, capable to record parameters of dielectric hysteresis loop of non-linear dielectrics. This measurement system makes possible automation and simplification of measurements process and preliminary data processing. Exemplary measurements of temperature characteristics of coercive field and spontaneous polarization of ferroelectric single crystals are also presented in the paper.
Domain-wall motion in random potential and hysteresis modeling
Pasquale, M.; Basso, V.; Bertotti, G. [IEN Galileo Ferraris and INFM C. so M. DAzeglio42, 10125Torino (Italy)] [IEN Galileo Ferraris and INFM C. so M. DAzeglio42, 10125Torino (Italy); Jiles, D.C.; Bi, Y. [Ames Laboratory, Iowa State University, 50011Ames, Iowa (United States)] [Ames Laboratory, Iowa State University, 50011Ames, Iowa (United States)
1998-06-01
Two different approaches to hysteresis modeling are compared using a common ground based on energy relations, defined in terms of dissipated and stored energy. Using the Preisach model and assuming that magnetization is mainly due to domain-wall motion, one can derive the expression of magnetization along a major loop typical of the Jiles{endash}Atherton model and then extend its validity to cases where mean-field effects and reversible contributions are present. {copyright} {ital 1998 American Institute of Physics.}
Hysteresis properties of titanomagnetites: Grain-size and compositional dependence
R. Day; M. Fuller; V. A. Schmidt
1977-01-01
Sized fractions of x = 0.6, 0.4, 0.2 and 0.0 titanomagnetites were studied with a vibration magnetometer. In the course particles (d > 150 mum), no compositional dependence of hysteresis parameters was found. HC was less than 50 Oe, HR\\/HC > 4 and JR\\/JS < 10-2, reflecting multi-domain behaviour. In contrast, fine particles (d ⋍ 0.1 mum) revealed systematic grain-size
Barkhausen discontinuities and hysteresis of ferromagnetics: New stochastic approach
NASA Astrophysics Data System (ADS)
Vengrinovich, Valeriy
2014-02-01
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.
Applications of hysteresis switching in parameter adaptive control
A. Stephen Morse; David Q. Mayne; Graham C. Goodwin
1992-01-01
The hysteresis switching algorithm of R.H. Middleton et al. (ibid., vol.33, no.1, p.50-8, Jan. 1988) is reexamined in a broader context. To demonstrate its utility, the algorithm is applied to various families of identifier-based parameterized controllers of both the direct and indirect control types. Application to the direct control type results in a model reference adaptive controller capable of stabilizing,
NASA Astrophysics Data System (ADS)
Cho, Mi Yeon; Han, Yoon Deok; Kang, Han Saem; Kim, Kihyun; Kim, Kyung Hwan; Cho, Min Ju; Choi, Dong Hoon; Joo, Jinsoo
2010-02-01
We report on the photoresponsive characteristics and hysteresis of soluble 6,13-bis(triisopropyl-silylethynyl; TIPS)-pentacene-based organic thin film transistors (OTFTs) with and without an annealing process. Under incident light, the hysteresis and memory effect increased for the annealed devices through photoinduced electron trapping and recombination at the gate-dielectric-semiconductor interface. To investigate the cause of the photoenhanced memory effect and hysteresis, we estimated the trapped electron densities from the threshold shift, while applying a gate bias to the annealed OTFTs under both dark and light conditions. A comparison of the characteristics of OTFT devices that are prepared under various conditions suggests that deep electron traps might be caused by the appearance of a domain boundary (i.e., cracks) in the annealed TIPS-pentacene film during the annealing process, which showed stable photoresponsive characteristics but relatively lower mobility.
Hysteresis of the resonance frequency of magnetostrictive bending cantilevers
NASA Astrophysics Data System (ADS)
Löffler, Michael; Kremer, Ramona; Sutor, Alexander; Lerch, Reinhard
2015-05-01
Magnetostrictive bending cantilevers are applicable for wirelessly measuring physical quantities such as pressure and strain. Exploiting the ?E-effect, the resonance frequency of the cantilevers is shifted because of a change in the magnetic biasing field. The biasing field, in turn, depends on the applied pressure or strain, respectively. With a view to the application as a reliable sensor, maximum sensitivity but minimum hysteresis in the biasing field/resonance frequency dependence is preferred. In this contribution, monomorph bending cantilevers fabricated using magnetostrictive Fe49Co49V2 and Metglas 2605SA1 are investigated regarding their applicability for future sensors. For this purpose, the biasing field-dependent polarization of the magnetostrictive materials and bending of the cantilevers are determined. Furthermore, a setup to magnetically bias the cantilevers and determine the bending resonance frequency is presented. Here, the resonance frequency is identified by measuring the impulse response employing a laser Doppler vibrometer. The measurement results reveal that cantilevers made of Fe49Co49V2 possess a distinct hysteretic behaviour at low magnetic biasing field magnitudes. This is ascribed to the polarization and bending hysteresis. Cantilevers fabricated using Metglas 2605SA1 feature a lower resonance frequency shift compared to cantilevers with Fe49Co49V2, which would result in a lower sensitivity of the sensor. However, their resonance frequency hysteresis is almost negligible.
The falsifiability of curve-hypotheses
Michael Martin
1965-01-01
2Popper's thesis is based on his contention that some curve-hypotheses require fewer observations to falsify them than do other curve-hypotheses. Katz, however, argues that all curve-hypotheses can be falsified by one observation. Since Popper identifies simplicity with falsifiability, Katz's argument, if correct, would show that on Popper's view of simplicity all curve-hypotheses are equally simple. Without wishing to question Katz's
NASA Astrophysics Data System (ADS)
He, Jin
2014-07-01
In the natural world, there exists one kind of structure which is beyond the scope of human laboratorial experiment. It is the structure of galaxies which is usually composed of billions of stars. Spiral galaxies are flat disk-shaped. There are two types of spiral galaxies. The spiral galaxies with some bar-shaped pattern are called barred spirals, and the ones without the pattern are called ordinary spirals. Longer-wavelength galaxy images (infrared, for example) show that ordinary spiral galaxies are basically an axi-symmetric disk that is called exponential disk. For a planar distribution of matter, Jin He defined Darwin curves in the plane as such that the ratio of the matter densities at both sides of the curve is constant along the curve. Therefore, the arms of ordinary spiral galaxies are Darwin curves. Now an important question is that: Are the arms of barred spiral galaxies the Darwin curves too? Fortunately, Jin He designed a piece of Galaxy Anatomy graphic software. With the software, not only can people simulate the stellar density distribution of barred spiral galaxies but also can draw the Darwin curves of the simulated galaxy structure. This paper shows partial evidence that the arms of galaxy NGC 3275, 4548 and 5921 follow Darwin curves.
Climate Hysteresis for Planets Orbiting Stars of Different Spectral Type
NASA Astrophysics Data System (ADS)
Shields, Aomawa; Meadows, V.; Bitz, C.; Pierrehumbert, R.; Joshi, M.; Robinson, T.; Planetary Laboratory, Virtual
2013-10-01
Planetary climate can be affected by the interaction of the host star spectral energy distribution with the wavelength-dependent reflectivity of ice and snow. We have explored this effect with a hierarchy of models. Results from both one-dimensional (1-D) radiative transfer and energy balance models and a three-dimensional (3-D) general circulation model indicate that terrestrial planets orbiting stars with higher near-UV radiation exhibit a stronger ice-albedo feedback. We found that ice extent is much greater on a planet orbiting an F-dwarf star than on a planet orbiting a G- or M-dwarf star at an equivalent flux distance, assuming fixed CO2 (present atmospheric level on Earth). The surface ice-albedo feedback effect becomes less important at the outer edge of the habitable zone for main-sequence stars, where the maintenance of surface liquid water requires high atmospheric CO2 concentrations. We show that ?3-10 bar of CO2 will entirely mask the climatic effect of ice and snow, leaving the outer limits of the habitable zone unaffected by the spectral dependence of water ice and snow albedo. However, less CO2 is needed to maintain open water for a planet orbiting an M-dwarf star than would be the case for hotter main-sequence stars. Both entrance into and exit out of a snowball state are sensitive to host star spectral energy distribution. Our simulations indicate a smaller climate hysteresis on M-dwarf planets, as measured by the range of instellation that permits multiple stable ice line latitudes. While M-dwarf planets appear less susceptible to snowball episodes than G- or F-dwarf planets over the course of their evolution, any snowball planets that are found orbiting M-dwarf stars may more easily melt out of these states as stellar luminosity increases over time. This effect is due to the lower-albedo ice on M-dwarf planets which, compounded with near-IR absorption by atmospheric gases, reduces the amount of increased stellar insolation, or “instellation”, necessary to melt these planets out of a snowball state.
Rational curves on Fermat hypersurfaces
Shen, Mingmin
2011-01-01
In this note we study rational curves on degree $p^r+1$ Fermat hypersurface in $\\PP^{p^r+1}_k$, where $k$ is an algebraically closed field of characteristic $p$. The key point is that the presence of Frobenius morphism makes the behavior of rational curves to be very different from that of charateristic 0. We show that if there exists $N_0$ such that for all $e\\geq N_0$ there is a degree $e$ very free rational curve on $X$, then $N_0> p^r(p^r-1)$.
Jo, Jeong-Wan; Park, Sung Kyu E-mail: skpark@cau.ac.kr; Kim, Yong-Hoon E-mail: skpark@cau.ac.kr
2014-07-28
In this report, photo-induced hysteresis, threshold voltage (V{sub T}) shift, and recovery behaviors in photochemically activated solution-processed indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs) are investigated. It was observed that a white light illumination caused negative V{sub T} shift along with creation of clockwise hysteresis in electrical characteristics which can be attributed to photo-generated doubly ionized oxygen vacancies at the semiconductor/gate dielectric interface. More importantly, the photochemically activated IGZO TFTs showed much reduced overall V{sub T} shift compared to thermally annealed TFTs. Reduced number of donor-like interface states creation under light illumination and more facile neutralization of ionized oxygen vacancies by electron capture under positive gate potential are claimed to be the origin of the less V{sub T} shift in photochemically activated TFTs.
NASA Astrophysics Data System (ADS)
Athukorallage, Bhagya; Iyer, Ram
2014-02-01
A capillary surface is the boundary between two immiscible fluids. When the two fluids are in contact with a solid surface, there is a contact line. The physical phenomena that cause dissipation of energy during a motion of the contact line are hysteresis in the contact angle dynamics, and viscosity of the fluids involved. In this paper, we consider a simplified problem where a liquid and a gas are bounded between two parallel plane surfaces with a capillary surface between the liquid-gas interface. The liquid-plane interface is considered to be non-ideal, which implies that the contact angle of the capillary surface at the interface is set-valued, and change in the contact angle exhibits hysteresis. We analyze a two-point boundary value problem for the fluid flow described by the Navier-Stokes and continuity equations, wherein a capillary surface with one contact angle is deformed to another with a different contact angle. The main contribution of this paper is that we show the existence of non-unique classical solutions to this problem, and numerically compute the dissipation.
Wu, Hong-Hui; Zhu, Jiaming; Zhang, Tong-Yi
2015-10-01
Phase field modelling and thermodynamic analysis are employed to investigate depolarization and compression induced large negative and positive electrocaloric effects (ECEs) in ferroelectric tetragonal crystalline nanoparticles. The results show that double-hysteresis loops of polarization versus electric field dominate at temperatures below the Curie temperature of the ferroelectric material, when the mechanical compression exceeds a critical value. In addition to the mechanism of pseudo-first-order phase transition (PFOPT), the double-hysteresis loops are also caused by the abrupt rise of macroscopic polarization from the abc phase to the c phase or the sudden fall of macroscopic polarization from the c phase to the abc phase when the temperature increases. This phenomenon is called the electric-field-induced-pseudo-phase transition (EFIPPT) in the present study. Similar to the two types of PFOPTs, the two types of EFIPPTs cause large negative and positive ECEs, respectively, and give the maximum absolute values of negative and positive adiabatic temperature change (ATC ?T). The temperature associated with the maximum absolute value of negative ATC ?T is lower than that associated with the maximum positive ATC ?T. Both maximum absolute values of ATC ?Ts change with the variation in the magnitude of an applied electric field and depend greatly on the compression intensity. PMID:26307461
Anhysteretic and biased first magnetization curves for Finemet-type toroidal samples
NASA Astrophysics Data System (ADS)
Varga, L. K.; Kovács, Gy.; Takács, J.
The anhysteretic and a set of biased first magnetization (BFMC) curves together with a set of first-order reversal curves (FORC) were measured and modeled by the hyperbolic T( x) model for a Finemet-type nanocrystalline toroidal sample with a round hysteresis loop. Similar to the FORC diagram, a "fingerprint"-like distribution has been obtained from a set of BFMC curves using the mixed second-derivate method of Pike. It is concluded that while the FORC diagram gives the distribution of coercive fields (or Preisach distribution), the BFMC diagram gives the distribution of the critical field where the domain wall magnetization become unstable and split up.
Investigation of karst hydrodynamics and organization using autocorrelations and T-? C curves
NASA Astrophysics Data System (ADS)
Valdes, Danièle; Dupont, Jean-Paul; Massei, Nicolas; Laignel, Beno?ˆt; Rodet, Joël
2006-10-01
SummaryIn karst systems, rain events often result in a decrease in conductivity (a tracer of dissolved phase transport) and an increase in turbidity (a tracer of suspended solids transport) at wells and springs. We investigated the response to rain events at five karst outlets (three springs and two wells) discharging from the cretaceous chalk aquifer of the Haute-Normandie region, France. As the input signal (rainfall) is relatively homogeneous spatially, the differences in the responses at the sites provide information on the internal organization of the karst systems and their hydrodynamic functioning. We used autocorrelation functions and turbidity-conductivity ( T-? C) hysteresis curves to analyze the responses. At short time scales, autocorrelation functions allow estimation of the inertia of the conduit flow system. The T-? C curves reflect the processes of deposition, resuspension, and direct transport of suspended solids within the karst network. The results show that: (i) a long memory effect for conductivity indicates storage of water in the karst network and deposition of suspended solids, and the transport of the dissolved phase and suspended solids is not the same; (ii) a short memory effect for conductivity indicates that transport of the dissolved phase and suspended solids is synchronous and direct. On the basis of the results at the five sites, we propose three conceptual models of hydrodynamic functioning.
Entropy Production and the Pressure-Volume Curve of the Lung
Oliveira, Cláudio L N; Bates, Jason H T; Andrade, José S; Suki, Béla
2015-01-01
We investigate analytically the production of entropy during a breathing cycle in healthy and diseased lungs. First, we calculate entropy production in healthy lungs by applying the laws of thermodynamics to the well-known transpulmonary pressure-volume ($P-V$) curves of the lung under the assumption that lung tissue behaves as an entropy spring-like rubber. The bulk modulus, $B$, of the lung is also derived from these calculations. Second, we extend this approach to elastic recoil disorders of the lung such as occur in pulmonary fibrosis and emphysema. These diseases are characterized by particular alterations in the $P-V$ relationship. For example, in fibrotic lungs $B$ increases monotonically with disease progression, while in emphysema the opposite occurs. These diseases can thus be mimicked simply by making appropriate adjustments to the parameters of the $P-V$ curve. Using Clausius's formalism, we show that entropy production, $\\Delta S$, is related to the hysteresis area, $\\Delta A$, enclosed by the $P...
Simple models for dynamic hysteresis loops calculation: Application to hyperthermia optimization
Carrey, J; Respaud, M
2010-01-01
To optimize the heating properties of magnetic nanoparticles (MNPs) in magnetic hyperthermia applications, it is necessary to calculate the area of their hysteresis loops in an alternating magnetic field. The three types of theories suitable to describe the hysteresis loops of MNPs are presented and compared to numerical simulations: equilibrium functions, Stoner-Wohlfarth model based theories (SWMBTs) and linear response theory (LRT). Suitable formulas to calculate the hysteresis area of major cycles are deduced from SWMBTs and from numerical simulations; the domain of validity of the analytical formula is explicitly studied. In the case of minor cycles, the hysteresis area calculations are based on the LRT. A perfect agreement between LRT and numerical simulations of hysteresis loops is obtained. The domain of validity of the LRT is explicitly studied. Formulas to calculate the hysteresis area at low field valid for any anisotropy of the MNP are proposed. Numerical simulations of the magnetic field dependen...
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 (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.
David Wolons; Farhan Gandhi; Brendon Malovrh
1998-01-01
An experimental investigation was conducted to determine the pseudoelastic hysteresis damping characteristics of Ni-Ti Shape Memory Alloy (SMA) wires. The comprehensive study examines the effects of cycling, oscillation frequency, strain amplitude, temperature, and static strain offset on the pseudoelastic stress-strain hysteresis of SMA wires under axial loading. Experimental data are obtained for complete austenite-martensite transformation hysteresis as well as partial
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.
Experimental characterization and modeling of rate-dependent hysteresis of a piezoceramic actuator
Mohammad Al Janaideh; Subhash Rakheja; Chun-Yi Su
2009-01-01
Laboratory experiments were performed to characterize the rate-dependent hysteresis properties of a piezoceramic actuator under harmonic, complex harmonic and triangular excitations in the 0.1–500Hz frequency range. The measured data were analyzed to describe the major and minor hysteresis loops as functions of frequency, magnitude and bias of the input voltage. The results revealed considerably larger hysteresis loop width and lower
NASA Astrophysics Data System (ADS)
Gambaryan, K. M.; Harutyunyan, V. G.; Aroutiounian, V. M.; Ai, Y.; Ashalley, E.; Wang, Z. M.
2015-06-01
The InAsSbP composition type-II quantum dots (QDs) are grown on a InAs(1?0?0) substrate from In-As-Sb-P quaternary liquid phase at a constant temperature in Stranski–Krastanow growth mode. Device structures in the form of photoconductive cells are prepared for investigation. Magnetospectroscopy and high-precision capacitance spectrometry are used to explore the QDs structure’s electric sheet resistance in a magnetic field and the capacitance (charge) law at lateral current flow. Aharonov–Bohm (AB) oscillations with the period of ?B = 0.38???±???0.04?T are found on the magnetoresistance curve at both room and liquid nitrogen temperatures. The influence of the QDs size distribution on the period of AB oscillations is investigated. The magnetoresistance hysteresis equals to ~50?m? and ~400?m? is revealed at room and liquid nitrogen temperature, respectively. The capacitance hysteresis (CH) and contra-directional oscillations are also detected. Behavior of the CH versus applied voltage frequency in the range f = 103–106?Hz is investigated. It is shown that the CH decreases with increasing frequency up to 106?Hz. The time constant and corresponding frequency for the QDs R–C parallel circuit (generator) equal to ? = 2.9???×???10?7?s and f?0 = 5.5???×???105?Hz, respectively, are calculated.
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.
NASA Astrophysics Data System (ADS)
Liu, Yanfang; Shan, Jinjun; Gabbert, Ulrich; Qi, Naiming
2013-11-01
A physics-based fractional-order Maxwell resistive capacitor (FOMRC) model is proposed to characterize nonlinear hysteresis and creep behaviors of a piezoelectric actuator (PEA). The Maxwell resistive capacitor (MRC) model is interpreted physically in the electric domain for PEAs. Based on this interpretation, the MRC model is modified to directly describe the relationship between the input voltage and the output displacement of a PEA. Then a procedure is developed to identify the parameters of the MRC model. This procedure is capable of being carried out using the measured input and output of a PEA only. A fractional-order dynamics is integrated into the MRC model to describe the effect of creep, as well as the detachment of hysteresis loops caused by creep. Moreover, the inverse FOMRC model is constructed to compensate for hysteresis and creep in an open-loop positioning application of PEAs. Simulation and experiments are carried out to validate the proposed model. The PEA compensated by the inverse FOMRC model shows an excellent linear behavior.
NASA Astrophysics Data System (ADS)
Zheng, Jiajia; Li, Yancheng; Li, Zhaochun; Wang, Jiong
2015-10-01
This paper presents multi-physics modeling of an MR absorber considering the magnetic hysteresis to capture the nonlinear relationship between the applied current and the generated force under impact loading. The magnetic field, temperature field, and fluid dynamics are represented by the Maxwell equations, conjugate heat transfer equations, and Navier–Stokes equations. These fields are coupled through the apparent viscosity and the magnetic force, both of which in turn depend on the magnetic flux density and the temperature. Based on a parametric study, an inverse Jiles–Atherton hysteresis model is used and implemented for the magnetic field simulation. The temperature rise of the MR fluid in the annular gap caused by core loss (i.e. eddy current loss and hysteresis loss) and fluid motion is computed to investigate the current–force behavior. A group of impulsive tests was performed for the manufactured MR absorber with step exciting currents. The numerical and experimental results showed good agreement, which validates the effectiveness of the proposed multi-physics FEA model.
Staudinger, Ulrike; Schlegel, Ralf; Weidisch, Roland; Fritzsche, Juliane; Kluppel, Manfred; Heinrich, G.; Mays, Jimmy; Uhrig, David; Hadjichristidis, Nikos
2008-01-01
Hysteresis behaviour of highly elastic multigraft copolymers with a polyisoprene (PI) backbone and branched polystyrene (PS) arms has been interpreted by applying the extended non-affine tube model of filler reinforced rubber elasticity (dynamic flocculation model), which takes into account that conformational fluctuations in bulk networks are strongly suppressed by packing effects. Originally, this model was developed to describe hyperelasticity of unfilled networks, and later, stress softening and hysteresis of filler reinforced elastomer materials like carbon black and silica filled rubbers. The evaluation of stress softening is obtained via pre-strain dependent hydrodynamic amplification of the rubber matrix by a fraction of rigid filler clusters with virgin filler filler bonds. The filler-induced hysteresis is described by a cyclic breakdown and re-aggregation of the residual fraction of more soft filler clusters with already broken filler filler bonds. We show, for the first time that the developed concept is in fair agreement with experimental stress strain data of superelastic PI PS multigraft copolymers. Depending on the PS-content and their functionality multigraft copolymers form microphase separated structures according to the constituting block copolymer concept, where the PS arms act as multi-domains in a PI matrix. The adaptation of the model is based on the assumption that the PS-domains are acting similar to filler clusters. The obtained microscopic material parameters appear reasonable for the description of the structure and mechanical properties of multigraft copolymers.
Huang, Liang; Ma, Yu Ting; Feng, Zhi Hua; Kong, Fan Rang
2010-09-01
Piezoelectric actuators exhibit large hysteresis between the applied voltage and their displacement. A switched capacitor charge pump is proposed to reduce hysteresis and linearize the movement of piezoelectric actuators. By pumping the same amount of charges into the piezoelectric actuator quantitatively, the actuator will be forced to change its length with constant step. Compared with traditional voltage and charge driving, experimental results demonstrated that the piezoelectric stack driven by the charge pump had less hysteresis over a large frequency range, especially at ultralow frequencies. A hysteresis of less than 2.01% was achieved over a frequency range of 0.01-20 Hz using the charge pump driver. PMID:20886997
Hysteresis of critical currents of superconducting bridges in low perpendicular magnetic fields
Aomine, T.; Tanaka, E.; Yamasaki, S.; Tani, K.; Yonekura, A.
1989-02-01
Hysteresis of critical currents I/sub c/ of superconducting bridges with In, Nb, and NbN has been studied in low perpendicular magnetic fields. Influences of bridge geometry, small field sweep, trapped flux, and bombardment of argon ions on the hysteresis were made clear. The experimental results suggest that the edge pinning and trapped flux in the bank of bridges are associated with the hysteresis. The peak value of I/sub c/ of NbN bridges, as well as granular Al and In bridges reported before, in decreasing fields agrees with the calculated pair-breaking current. The origin of the hysteresis is discussed.
H. J. de Vega
1993-02-15
Progress on the physics of strings in curved spacetime are comprehensively reviewed.We start by showing through renormalization group arguments that a meaningful quantum theory of gravity must be finite and must include all particle physics.Then, we review classical and quantum string propagation in curved spacetimes.We start by the general expansion method proposed by de Vega and S\\'anchez in 1987. The particle transmutation phenomena in asymptotically flat spacetimes are detailed including fermion-boson transitions in supergravity backgrounds.The next chapters review the exactly solvable cases of string propagation: shock waves, singular plane waves, conical spacetimes and de Sitter cosmological spacetime. The calculation of various physical quantities like the string mass and the energy-momentum tensor shows that classical and quantum string propagation in shock-waves and singular plane waves is physically meaningful and full of interesting new phenomena.The important phenomenom of {\\bf string stretching} that takes place when strings fall into spacetime singularities and in expanding universes is analyzed.We conclude by reporting on strings in de Sitter spacetime, where the string equations are integrable and reduce to the sinh-Gordon equation and to integrable generalizations of it. Lectures delivered at the ERICE SCHOOL ``STRING QUANTUM GRAVITY AND PHYSICS AT THE PLANCK ENERGY SCALE'', 21-28 June 1992 , to appear in the Proceedings edited by N. S\\'anchez, World Scientific.
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.
A two-dimensional adsorption kinetic model for thermal hysteresis activity in antifreeze proteins
NASA Astrophysics Data System (ADS)
Li, Q. Z.; Yeh, Y.; Liu, J. J.; Feeney, R. E.; Krishnan, V. V.
2006-05-01
Antifreeze proteins (AFPs) and antifreeze glycoproteins (AFGPs), collectively abbreviated as AF(G)Ps, are synthesized by various organisms to enable their cells to survive in subzero environments. Although the AF(G)Ps are markedly diverse in structure, they all function by adsorbing to the surface of embryonic ice crystals to inhibit their growth. This adsorption results in a freezing temperature depression without an appreciable change in the melting temperature. The difference between the melting and freezing temperatures, termed thermal hysteresis (TH), is used to detect and quantify the antifreeze activity. Insights from crystallographic structures of a number of AFPs have led to a good understanding of the ice-protein interaction features. Computational studies have focused either on verifying a specific model of AFP-ice interaction or on understanding the protein-induced changes in the ice crystal morphology. In order to explain the origin of TH, we propose a novel two-dimensional adsorption kinetic model between AFPs and ice crystal surfaces. The validity of the model has been demonstrated by reproducing the TH curve on two different ?-helical AFPs upon increasing the protein concentration. In particular, this model is able to accommodate the change in the TH behavior observed experimentally when the size of the AFPs is increased systematically. Our results suggest that in addition to the specificity of the AFPs for the ice, the coverage of the AFPs on the ice surface is an equally necessary condition for their TH activity.
NASA Astrophysics Data System (ADS)
Erta?, Mehmet
2015-09-01
Keskin and Erta? (2009) presented a study of the magnetic properties of a mixed spin (2, 5/2) ferrimagnetic Ising model within an oscillating magnetic field. They employed dynamic mean-field calculations to find the dynamic phase transition temperatures, the dynamic compensation points of the model and to present the dynamic phase diagrams. In this work, we extend the study and investigate the dynamic hysteresis behaviors for the two-dimensional (2D) mixed spin (2, 5/2) ferrimagnetic Ising model on a hexagonal lattice in an oscillating magnetic field within the framework of dynamic mean-field calculations. The dynamic hysteresis curves are obtained for both the ferromagnetic and antiferromagnetic interactions and the effects of the Hamiltonian parameters on the dynamic hysteresis behaviors are discussed in detail. The thermal behaviors of the coercivity and remanent magnetizations are also investigated. The results are compared with some theoretical and experimental works and a qualitatively good agreement is found. Finally, the dynamic phase diagrams depending on the frequency of an oscillating magnetic field in the plane of the reduced temperature versus magnetic field amplitude is examined and it is found that the dynamic phase diagrams display richer dynamic critical behavior for higher values of frequency than for lower values.
Dan Xie
2014-09-29
N=1 curve is defined for four dimensional class S theory using Cayley-Hamilton theorem for two commuting matrices. The curve consists of three ingredients: 1: A set of N+1 degree N equations defining a curve; 2: a set of constraints relating the coefficients in the curve; 3: a canonically defined differential. We then extract from spectral curve various physical information such as the space of moduli fields, chiral ring relations, full moduli space, etc. Many examples are discussed, and the curve recovers the intricate vacua structure which often involves highly non-trivial field theory dynamics such as monopole condensation, dynamical generated superpotential, Seiberg duality, etc.
Stojanovski, Bosko M.; Hunter, Gregory A.; Jahn, Martina; Jahn, Dieter; Ferreira, Gloria C.
2014-01-01
5-Aminolevulinate (ALA), an essential metabolite in all heme-synthesizing organisms, results from the pyridoxal 5?-phosphate (PLP)-dependent enzymatic condensation of glycine with succinyl-CoA in non-plant eukaryotes and ?-proteobacteria. The predicted chemical mechanism of this ALA synthase (ALAS)-catalyzed reaction includes a short-lived glycine quinonoid intermediate and an unstable 2-amino-3-ketoadipate intermediate. Using liquid chromatography coupled with tandem mass spectrometry to analyze the products from the reaction of murine erythroid ALAS (mALAS2) with O-methylglycine and succinyl-CoA, we directly identified the chemical nature of the inherently unstable 2-amino-3-ketoadipate intermediate, which predicates the glycine quinonoid species as its precursor. With stopped-flow absorption spectroscopy, we detected and confirmed the formation of the quinonoid intermediate upon reacting glycine with ALAS. Significantly, in the absence of the succinyl-CoA substrate, the external aldimine predominates over the glycine quinonoid intermediate. When instead of glycine, l-serine was reacted with ALAS, a lag phase was observed in the progress curve for the l-serine external aldimine formation, indicating a hysteretic behavior in ALAS. Hysteresis was not detected in the T148A-catalyzed l-serine external aldimine formation. These results with T148A, a mALAS2 variant, which, in contrast to wild-type mALAS2, is active with l-serine, suggest that active site Thr-148 modulates ALAS strict amino acid substrate specificity. The rate of ALA release is also controlled by a hysteretic kinetic mechanism (observed as a lag in the ALA external aldimine formation progress curve), consistent with conformational changes governing the dissociation of ALA from ALAS. PMID:24920668
Contact angle hysteresis and pinning at periodic defects in statics
NASA Astrophysics Data System (ADS)
Iliev, Stanimir; Pesheva, Nina; Nikolayev, Vadim S.
2014-07-01
This article deals with the theoretical prediction of the wetting hysteresis on nonideal solid surfaces in terms of the surface heterogeneity parameters. The spatially periodical chemical heterogeneity is considered. We propose precise definitions for both the advancing and the receding contact angles for the Wilhelmy plate geometry. It is well known that in such a system, a multitude of metastable states of the liquid meniscus occurs for each different relative position of the defect pattern on the plate with respect to the liquid level. As usual, the static advancing and receding angles are assumed to be a consequence of the preceding contact line motion in the respective direction. It is shown how to select the appropriate states among all metastable states. Their selection is discussed. The proposed definitions are applicable to both the static and the dynamic contact angles on heterogeneous surfaces. The static advancing and receding angles are calculated for two examples of periodic heterogeneity patterns with sharp borders: the horizontal alternating stripes of a different wettability (studied analytically) and the doubly periodic pattern of circular defects on a homogeneous base (studied numerically). The wetting hysteresis is determined as a function of the defect density and the spatial period. A comparison with the existing results is carried out.
Contact angle hysteresis and pinning at periodic defects in statics.
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
Television Quiz Show Simulation
ERIC Educational Resources Information Center
Hill, Jonnie Lynn
2007-01-01
This article explores the simulation of four television quiz shows for students in China studying English as a foreign language (EFL). It discusses the adaptation and implementation of television quiz shows and how the students reacted to them.
Characterization upon electrical hysteresis and thermal diffusion of TiAl3Ox dielectric film
2011-01-01
In this paper, we have investigated the electrical properties of TiAl3Ox film as electrical gate insulator deposited by pulsed laser deposition and presented a simple method to describe the thermal diffusion behaviors of metal atoms at TiAl3Ox/Si interfacial region in detail. The TiAl3Ox films show obvious electrical hysteresis by the capacitance-voltage measurements after post-annealing treatment. By virtue of the diffusion models composed of TiAl3Ox film and silicon, the diffusion coefficient and the diffusion activation energy of the Ti and Al atoms are extracted. It is valuable to further investigate the pseudobinary oxide system in practice. PACS: 77.55.-g; 81.15.Fg; 81.40.Gh. PMID:22011364
Amplitude and frequency dependence of hysteresis loss in a magnet-superconductor levitation system
Yang, Z.J.; Hull, J.R.; Mulcahy, T.M.; Rossing, T.D.
1995-08-01
Using an electromagnetically controlled mechanical pendulum, we measured the energy loss for different amplitudes in a magnetic levitation system that contained high temperature superconductors (HTSs). Two procedures were followed to measure losses at 77 K for frequencies of 93.8 mHz to 80 Hz. In the first procedure, the distance between the permanent magnet and the HTS levitator was the same as that during (field) cooling. In the second procedure, the magnet was lowered (after cooling) closer to the HTS levitator before the measurements were performed. The experimental data show that these two procedures give essentially the same results at the same distance despite different cooling (and magnetization) histories for melt-textured YBaCuO levitators, and the frequency-independent energy loss is a power-law function of amplitude. We attribute the energy loss to magnetic hysteresis in the superconductor. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
Hysteresis and the role of nucleation and growth in the hydrogenation of Mg nanolayers.
Mooij, Lennard; Dam, Bernard
2013-02-28
We investigated the hydrogenation of 3 and 10 nm Mg layers sandwiched between Ti using an optical transmission technique (hydrogenography). We observe in situ the two dimensional nucleation and growth of single hydride domains of up to several millimeters in diameter. The low density of nuclei points to preferential nucleation at heterogeneous sites. From an analysis of the growth kinetics we deduce an extremely large edge boundary energy, which we relate to the plastic deformations inherent to the 30% volume expansion of the MgH(2). We find that the nucleation and growth process affects the hysteresis between absorption and desorption. Especially, the absorption branch can be lowered when nucleation barriers are removed. Our results show that when discussing the effect of nano-structuring on hydrogenation it may be quite complex to distinguish the thermodynamic and kinetic effects involved. PMID:23329172
Discrete regenerative fuel cell reduces hysteresis for sustainable cycling of water
NASA Astrophysics Data System (ADS)
Park, Kiwon; Lee, Jungkoo; Kim, Hyung-Man; Choi, Kap-Seung; Hwang, Gunyong
2014-04-01
The discrete regenerative fuel cell is being developed as a residential power control that synchronizes with a renewables load which fluctuates significantly with the time and weather. The power of proton exchange membrane fuel cells can be scaled-up adjustably to meet the residential power demand. As a result, scale-ups from a basic unit cell with a 25 cm2 active area create a serpentine flow-field on an active area of 100 cm2 and take into account the excessive current and the remaining power obtained by stacking single cells. Operating a fuel cell utilising oxygen produced by the electrolyser instead of air improves the electrochemical reaction and the water balance. Furthermore, the performance test results with oxygen instead of air show almost no hysteresis, which results in the very stable operation of the proton exchange membrane fuel cell as well as the sustainable cycle of water by hydrogen and oxygen mediums.
Discrete regenerative fuel cell reduces hysteresis for sustainable cycling of water
Park, Kiwon; Lee, Jungkoo; Kim, Hyung-Man; Choi, Kap-Seung; Hwang, Gunyong
2014-01-01
The discrete regenerative fuel cell is being developed as a residential power control that synchronizes with a renewables load which fluctuates significantly with the time and weather. The power of proton exchange membrane fuel cells can be scaled-up adjustably to meet the residential power demand. As a result, scale-ups from a basic unit cell with a 25?cm2 active area create a serpentine flow-field on an active area of 100?cm2 and take into account the excessive current and the remaining power obtained by stacking single cells. Operating a fuel cell utilising oxygen produced by the electrolyser instead of air improves the electrochemical reaction and the water balance. Furthermore, the performance test results with oxygen instead of air show almost no hysteresis, which results in the very stable operation of the proton exchange membrane fuel cell as well as the sustainable cycle of water by hydrogen and oxygen mediums. PMID:24699531
NASA Astrophysics Data System (ADS)
Li, Yi; Xu, Ben; Hu, Shenyang; Li, Yulan; Li, Qiulin; Liu, Wei
2015-07-01
The magnetic hysteresis loops and Barkhausen noise of a single ?-iron with nonmagnetic particles are simulated to investigate into the magnetic hardening due to Cu-rich precipitates in irradiated reactor pressure vessel (RPV) steels. Phase field method basing Landau-Lifshitz-Gilbert (LLG) equation is used for this simulation. The results show that the presence of the nonmagnetic particle could result in magnetic hardening by making the nucleation of reversed domains difficult. The coercive field is found to increase, while the intensity of Barkhausen noise voltage is decreased when the nonmagnetic particle is introduced. Simulations demonstrate the impact of nucleation field of reversed domains on the magnetization reversal behavior and the magnetic properties.
Li, Yi; Xu, Ben; Hu, Shenyang; Li, Yulan; Li, Qiulin; Liu, Wei
2015-07-01
The magnetic hysteresis loops and Barkhausen noise of a single ?-iron with nonmagnetic particles are simulated to investigate into the magnetic hardening due to Cu-rich precipitates in irradiated reactor pressure vessel (RPV) steels. Phase field method basing Landau-Lifshitz-Gilbert (LLG) equation is used for this simulation. The results show that the presence of the nonmagnetic particle could result in magnetic hardening by making the nucleation of reversed domains difficult. The coercive field is found to increase, while the intensity of Barkhausen noise voltage is decreased when the nonmagnetic particle is introduced. Simulations demonstrate the impact of nucleation field of reversed domainsmore »on the magnetization reversal behavior and the magnetic properties.« less
Effect of Dangling Chains on Adhesion Hysteresis of Silicone Elastomers, Probed by JKR Test
Paris-Sud 11, Université de
,4 The efficiency of connectors molecules to promote adhesion at elastomer interfaces has been investigated by manyEffect of Dangling Chains on Adhesion Hysteresis of Silicone Elastomers, Probed by JKR Test Nicolas test has been used to quantify adhesion hysteresis between PDMS model networks having different amount
L1 Adaptive Control of Hysteresis in Smart Materials Xiang Fan and Ralph C. Smith
a mathematical model for describing hysteresis. On the basis of the hysteresis model, a robust adaptive inverse model is efficient enough to be inverted in real time. The second strategy entails direct incorporation for Research in Scientific Computation Department of Mathematics North Carolina State University Raleigh, NC
Partial and Full Inverse Compensation for Hysteresis in Smart Material Systems
constitutive nonlinearities and hysteresis at moderate to high drive levels. While feedback mechanisms dynamics and phase lags associated with the two phenomena will degrade the controller performance at high discuss two techniques to compensate for hysteresis in high performance trans ducers. The first is based
Numerical simulation for a two-phase porous medium flow problem with rate independent hysteresis$
Turova, Varvara
Numerical simulation for a two-phase porous medium flow problem with rate independent hysteresis$ M¨unchen, Boltzmannstr. 3, 80807, Germany a r t i c l e i n f o Keywords: Two-phase flow Porous media Hysteresis Play of two phases. & 2011 Published by Elsevier B.V. 1. Introduction The multiphase nature of a flow
A Uni#12;ed Methodology for Modeling Hysteresis in Ferroelectric, Ferromagnetic and Ferroelastic Materials Ralph C. Smith 1 and Jordan E. Massad Center for Research in Scienti#12;c Computation Department on the development of uni#12;ed techniques for mathematically modeling the hysteresis and constitutive nonlinearities
A Homogenized Free Energy Model for Hysteresis in Thin-film Shape Memory Alloys
A Homogenized Free Energy Model for Hysteresis in Thin-film Shape Memory Alloys Jordan E. Massad1 the nonlinearities and hysteresis inherent to SMAs. The model is based on free energy principles combined the full potential of SMA actuators, it is necessary to develop models that characterize the nonlinear
Hysteresis and process stability in reactive high power impulse magnetron sputtering of metal oxides
Montri Aiempanakit; Tomás Kubart; Petter Larsson; Kostas Sarakinos; Jens Jensen; Ulf Helmersson
2011-01-01
In the further development of reactive sputter deposition, strategies which allow for stabilization of the transition zone between the metallic and compound modes, elimination of the process hysteresis, and increase of the deposition rate, are of particular interest. In this study, the hysteresis behavior and the characteristics of the transition zone during reactive high power impulse magnetron sputtering (HiPIMS) of
3-D numerical simulation of contact angle hysteresis for microscale two phase flow
Hidrovo, Carlos H.
3-D numerical simulation of contact angle hysteresis for microscale two phase flow Chen Fang the effects of contact angle hysteresis. A transient model is developed by correcting boundary force balances through specification of the local contact angle and instantaneously updating the local angle values based
[LR7573E]059101PRE Contact-angle hysteresis in solid-on-solid wetting
Attard, Phil
PROOF COPY [LR7573E]059101PRE Contact-angle hysteresis in solid-on-solid wetting Phil Attard Ian. Hysteresis is demonstrated between the loading and the unloading cycles: the receding contact angle exceeds s : 68.03.Cd, 62.20.Fe, 68.35.Md The angles between the phase boundaries at a line of three phase contact
Mohammad Al Janaideh; Subhash Rakheja; Chun-Yi Su
2009-01-01
Smart actuators, such as shape memory alloy (SMA) and magnetostrictive actuators, exhibit saturation nonlinearity and hysteresis that may be symmetric or asymmetric. The Prandtl-Ishlinskii model employing classical play operators has been used to describe the hysteresis properties of smart actuators that are symmetric in nature. In this study, the application of a generalized play operator capable of characterizing symmetric as
Observations of an Impurity-driven Hysteresis Behavior in Ice Crystal Growth at Low Pressure
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 that governs the crystal formation process. Toward this end, we have constructed an experimental apparatus
Hysteresis Caused by Water Molecules in Carbon Nanotube Field-Effect
Javey, Ali
molecules around the nanotubes, including SiO2 surface-bound water proximal to the nanotubes. Hysteresis-gate) characteristics and attributed the hysteresis to charge traps in bulk SiO2, oxygen-related defect trap sites near-bound water that cannot be fully removed by pumping in vacuum. We also report that a simple polymer coating
Sengun, Mehmet Haluk
Modular Curves David Loeer Notes by Florian Bouyer Copyright (C) Bouyer 2014. Permission is granted://www.gnu.org/licenses/fdl.html Contents 0 Wae 2 0.1 Recap of modular forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1 Modular Curves as Riemann Surfaces 3 1.1 Modular curves as topological spaces
Nitrogen adsorption data for the powder form of the PMO shows a diagnostic type IV
Vinnikov, Konstantin
with well-defined capillary conden- sation and very little hysteresis (Fig. 4). The Brunauer Emmett Teller experiments showed that no significant Si-C bond cleavage occurred during synthesis (fig. S4, A to C R equal to I, Br, and Et) remained intact after synthesis and extraction, because the chemical
Connord, V; Tan, R P; Carrey, J; Respaud, M
2014-01-01
A low-cost and simple setup for measuring the high-frequency hysteresis loops of magnetic samples is described. An AMF in the range 6-100 kHz with amplitude up to 80 mT is produced by a Litz wire coil. The latter is air-cooled using a forced-air approach so no water flow is required to run the setup. High-frequency hysteresis loops are measured using a system of pick-up coils and numerical integration of signals. Reproducible measurements are obtained in the frequency range of 6-56 kHz. Measurement examples on ferrite cylinders and on iron oxide nanoparticle ferrofluids are shown. Comparison with other measurement methods of the hysteresis loop area (complex susceptibility, quasi-static hysteresis loops and calorific measurements) is provided and shows the coherency of the results obtained with this setup. This setup is well adapted to the magnetic characterization of colloidal solutions of MNPs for magnetic hyperthermia applications.
NASA Astrophysics Data System (ADS)
Connord, V.; Mehdaoui, B.; Tan, R. P.; Carrey, J.; Respaud, M.
2014-09-01
A setup for measuring the high-frequency hysteresis loops of magnetic samples is described. An alternating magnetic field in the range 6-100 kHz with amplitude up to 80 mT is produced by a Litz wire coil. The latter is air-cooled using a forced-air approach so no water flow is required to run the setup. High-frequency hysteresis loops are measured using a system of pick-up coils and numerical integration of signals. Reproducible measurements are obtained in the frequency range of 6-56 kHz. Measurement examples on ferrite cylinders and on iron oxide nanoparticle ferrofluids are shown. Comparison with other measurement methods of the hysteresis loop area (complex susceptibility, quasi-static hysteresis loops, and calorific measurements) is provided and shows the coherency of the results obtained with this setup. This setup is well adapted to the magnetic characterization of colloidal solutions of magnetic nanoparticles for magnetic hyperthermia applications.
NSDL National Science Digital Library
Children's Museum of Houston
2011-01-01
With a laser pointer and some household items, learners can create their own laser light show. They can explore diffuse reflection, refraction and diffraction. The webpage includes a video which shows how to set up the activity and also includes scientific explanation. Because this activity involves lasers, it requires adult supervision.
Characterization of hysteresis in magnetic systems: A Preisach approach
NASA Astrophysics Data System (ADS)
Mitchler, Patricia Darlene
The phenomenon of hysteresis is perhaps the most widely recognized microscopic manifestation of magnetic ordering, and is the principal feature which is responsible for technologically-oriented applications of magnetic materials such as permanent magnets and recording media. Interest in a phenomenological model of hysteresis originally proposed by Preisach in 1935 has been renewed recently, particularly in engineering applications, such as the characterization of magnetic recording media and magnetostrictive materials. Thus, a rigorous assessment of the capabilities and limitations of the Preisach model for characterizing magnetic materials is of considerable importance from both fundamental and technological perspectives. The fundamental characteristics of hysteresis are discussed and a theoretical background for the processes involved in magnetic systems is established. A generalized version of the scalar Preisach model, which includes original contributions, is developed to extend the model's abilities to describe the effects of the structure of the initially demagnetized state, the presence and nature of interactions, the system's coercive field distribution, and especially, the effects of temperature and experimental wart time, on the observed hysteretic properties of a variety of magnetic systems including spin glasses, ferromagnets, ferrimagnets, and superparamagnets. The moment and remanence of magnetic systems are measured as a function of applied field and temperature, using both a vibrating sample magnetometer (VSM) and a SQUID-based magnetometer. A Preisach analysis of the data is used to characterize the irreversible response of six magnetic systems: CrO 2 audio tape; magnetoferritin; a Nd2Fe14B permanent magnet; a floppy disk medium; and longitudinal and perpendicular cobalt-chromium-based hard disk materials. The ambiguous nature of tools presently used to analyze the nature of magnetic systems, such as the application of Henkel plots to the analysis of interaction effects, is demonstrated and alternative Preisach-based analysis schemes are presented. The physical significance of parameters, which emerged from the Preisach calculations, is discussed in detail and modifications are proposed to model this array of real magnetic systems. These changes to the scalar Preisach model extend its capabilities, while maintaining the inherent simplicity of a scalar model. Limitations of the model are also discussed critically, and suggestions for future generalizations are made.
NSDL National Science Digital Library
The Diane Rehm Show has its origins in a mid-day program at WAMU in Washington, D.C. Diane Rehm came on to host the program in 1979, and in 1984 it was renamed "The Diane Rehm Show". Over the past several decades, Rehm has played host to hundreds of guests, include Archbishop Desmond Tutu, Julie Andrews, and President Bill Clinton. This website contains an archive of her past programs, and visitors can use the interactive calendar to look through past shows. Those visitors looking for specific topics can use the "Topics" list on the left-hand side of the page, or also take advantage of the search engine. The show has a number of social networking links, including a Facebook page and a Twitter feed.
ERIC Educational Resources Information Center
Kirkpatrick, Larry D.; Rugheimer, Mac
1979-01-01
Describes the viewing sessions and the holograms of a holographic road show. The traveling exhibits, believed to stimulate interest in physics, include a wide variety of holograms and demonstrate several physical principles. (GA)
Phase nucleation in curved space
NASA Astrophysics Data System (ADS)
Gómez, Leopoldo R.; García, Nicolás A.; Vitelli, Vincenzo; Lorenzana, José; Vega, Daniel A.
2015-04-01
Nucleation and growth is the dominant relaxation mechanism driving first-order phase transitions. In two-dimensional flat systems, nucleation has been applied to a wide range of problems in physics, chemistry and biology. Here we study nucleation and growth of two-dimensional phases lying on curved surfaces and show that curvature modifies both critical sizes of nuclei and paths towards the equilibrium phase. In curved space, nucleation and growth becomes inherently inhomogeneous and critical nuclei form faster on regions of positive Gaussian curvature. Substrates of varying shape display complex energy landscapes with several geometry-induced local minima, where initially propagating nuclei become stabilized and trapped by the underlying curvature.
NASA Astrophysics Data System (ADS)
Foster, David; Foster, Jacob; Paczuski, Maya; Grassberger, Peter
2010-04-01
Ensembles of networks are used as null models in many applications. However, simple null models often show much less clustering than their real-world counterparts. In this paper, we study a “biased rewiring model” where clustering is enhanced by means of a fugacity as in the Strauss (or “triangle”) model, but where the number of links attached to each node is strictly preserved. Similar models have been proposed previously in Milo [Science 298, 824 (2002)]. Our model exhibits phase transitions as the fugacity is changed. For regular graphs (identical degrees for all nodes) with degree k>2 we find a single first order transition. For all nonregular networks that we studied (including Erdös-Rényi, scale-free, and several real-world networks) multiple jumps resembling first order transitions appear. The jumps coincide with the sudden emergence of “cluster cores:” groups of highly interconnected nodes with higher than average degrees, where each edge participates in many triangles. Hence, clustering is not smoothly distributed throughout the network. Once formed, the cluster cores are difficult to remove, leading to strong hysteresis. To study the cluster cores visually, we introduce q -clique adjacency plots. Cluster cores constitute robust communities that emerge spontaneously from the triangle generating process, rather than being put explicitly into the definition of the model. All the quantities we measured including the modularity, assortativity, clustering and number of four and five-cliques exhibit simultaneous jumps and are equivalent order parameters. Finally, we point out that cluster cores produce pitfalls when using the present (and similar) models as null models for strongly clustered networks, due to strong hysteresis which leads to broken ergodicity on realistic sampling time scales.
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
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
Hysteresis in coral reefs under macroalgal toxicity and overfishing.
Bhattacharyya, Joydeb; Pal, Samares
2015-03-01
Macroalgae and corals compete for the available space in coral reef ecosystems.While herbivorous reef fish play a beneficial role in decreasing the growth of macroalgae, macroalgal toxicity and overfishing of herbivores leads to proliferation of macroalgae. The abundance of macroalgae changes the community structure towards a macroalgae-dominated reef ecosystem. We investigate coral-macroalgal phase shifts by means of a continuous time model in a food chain. Conditions for local asymptotic stability of steady states are derived. It is observed that in the presence of macroalgal toxicity and overfishing, the system exhibits hysteresis through saddle-node bifurcation and transcritical bifurcation. We examine the effects of time lags in the liberation of toxins by macroalgae and the recovery of algal turf in response to grazing of herbivores on macroalgae by performing equilibrium and stability analyses of delay-differential forms of the ODE model. Computer simulations have been carried out to illustrate the different analytical results. PMID:25708511
Inferring Pore Size and Network Structure from Sorption Hysteresis
Matthew B. Pinson; Hamlin M. Jennings; Martin Z. Bazant
2014-02-14
Sorption experiments are widely used to infer the pore size distribution of a mesoporous material. We present a simple model that explains the hysteresis observed on desorption in such experiments. The model is based on well-established relationships between the radius of a pore and the partial pressure at which it will fill, but additionally describes of the connectivity of the pore network. The model is able to explain both primary and scanning sorption isotherms for a range of materials with wide pore size distributions, such as cement paste and dental enamel. It allows quantification of the prevalence of macropores in the material, even though these pores are never filled during the sorption experiments. A distinct bump in the desorption isotherms is attributed to spinodal decomposition (or cavitation) at a partial pressure that depends on temperature, and experiments across a range of sorbents and sorbates are consistent with a universal scaling.
Wafer-level hysteresis-free resonant carbon nanotube transistors.
Cao, Ji; Bartsch, Sebastian T; Ionescu, Adrian M
2015-03-24
We report wafer-level fabrication of resonant-body carbon nanotube (CNT) field-effect transistors (FETs) in a dual-gate configuration. An integration density of >10(6) CNTFETs/cm(2), an assembly yield of >80%, and nanoprecision have been simultaneously obtained. Through combined chemical and thermal treatments, hysteresis-free (in vacuum) suspended-body CNTFETs have been demonstrated. Electrostatic actuation by lateral gate and FET-based readout of mechanical resonance have been achieved at room temperature. Both upward and downward in situ frequency tuning has been experimentally demonstrated in the dual-gate architecture. The minuscule mass, high resonance frequency, and in situ tunability of the resonant CNTFETs offer promising features for applications in radio frequency signal processing and ultrasensitive sensing. PMID:25752991
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.
Hysteresis-free nanoplasmonic Pd-Au alloy hydrogen sensors.
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
Asymmetric Magnetization Reversal in Exchange-Biased Hysteresis Loops
Fitzsimmons, M. R.; Yashar, P.; Leighton, C.; Schuller, Ivan K.; Nogues, J.; Majkrzak, C. F.; Dura, J. A.
2000-04-24
Polarized neutron reflectometry is used to probe the in-plane projection of the net-magnetization vector M(vector sign) of polycrystalline Fe films exchange coupled to twinned (110) MnF{sub 2} or FeF{sub 2} antiferromagnetic (AF) layers. The magnetization reversal mechanism depends upon the orientation of the cooling field with respect to the twinned microstructure of the AF, and whether the applied field is increased to (or decreased from) a positive saturating field; i.e., the magnetization reversal is asymmetric. The reversal of the sample magnetization from one saturated state to the other occurs via either domain wall motion or magnetization rotation on opposite sides of the same hysteresis loop. (c) 2000 The American Physical Society.
Hysteresis in Magnetic Shape Memory Composites: Modeling and Simulation
Conti, Sergio; Rumpf, Martin
2015-01-01
Magnetic shape memory alloys are characterized by the coupling between a structural phase transition and magnetic one. This permits to control the shape change via an external magnetic field, at least in single crystals. Composite materials with single-crystalline particles embedded in a softer matrix have been proposed as a way to overcome the blocking of the transformation at grain boundaries. We investigate hysteresis phenomena for small NiMnGa single crystals embedded in a polymer matrix for slowly varying magnetic fields. The evolution of the microstructure is studied within the rate-independent variational framework proposed by Mielke and Theil (1999). The underlying variational model incorporates linearized elasticity, micromagnetism, stray field and a dissipation term proportional to the volume swept by the phase boundary. The time discretization is based on an incremental minimization of the sum of energy and dissipation. A backtracking approach is employed to approximately ensure the global minimali...
GENERALIZED MORDELL CURVES, GENERALIZED FERMAT CURVES, AND THE HASSE PRINCIPLE
Nguyen, Dong Quan Ngoc
GENERALIZED MORDELL CURVES, GENERALIZED FERMAT CURVES, AND THE HASSE PRINCIPLE NGUYEN NGOC DONG. The descending chain condition on sequences of curves 18 6. Certain generalized Fermat curves violating the Hasse of generalized Fermat curves 33 9. Epilogue 35 References 45 Abstract. A generalized Mordell curve of degree n 3
ERIC Educational Resources Information Center
Mathieu, Aaron
2000-01-01
Uses a talk show activity for a final assessment tool for students to debate about the ozone hole. Students are assessed on five areas: (1) cooperative learning; (2) the written component; (3) content; (4) self-evaluation; and (5) peer evaluation. (SAH)
Honored Teacher Shows Commitment.
ERIC Educational Resources Information Center
Ratte, Kathy
1987-01-01
Part of the acceptance speech of the 1985 National Council for the Social Studies Teacher of the Year, this article describes the censorship experience of this honored social studies teacher. The incident involved the showing of a videotape version of the feature film entitled "The Seduction of Joe Tynan." (JDH)
ERIC Educational Resources Information Center
Cech, Scott J.
2008-01-01
Having students show their skills in three dimensions, known as performance-based assessment, dates back at least to Socrates. Individual schools such as Barrington High School--located just outside of Providence--have been requiring students to actively demonstrate their knowledge for years. The Rhode Island's high school graduating class became…
ERIC Educational Resources Information Center
Frasier, Debra
2008-01-01
In the author's book titled "The Incredible Water Show," the characters from "Miss Alaineus: A Vocabulary Disaster" used an ocean of information to stage an inventive performance about the water cycle. In this article, the author relates how she turned the story into hands-on science teaching for real-life fifth-grade students. The author also…
New South Wales, University of
Hide / Show Animal Ethics Modification for Approved Application You are here: Animal Ethics. Administration B. Requested Modification C. Animal Use & Numbers D. Animal Housing E. Animal Location F. Monitoring G. Animals Fate H. Declaration of Participants Attachments Check & Final Submit Icon legend: You
New South Wales, University of
Hide / Show Animal Ethics Modification for Approved Application New personnel or updated role since last approval New person nominated since last approval You are here: Animal Ethics Application or personnel with new role in this project who will be involved with the use of animals in this project Each
New South Wales, University of
Hide / Show Animal Ethics Application for Project Approval You are here: Animal Ethics Application by this or another ACEC? Yes No A.13 * Location (building and room number if appropriate) where animals are to be held during this project: A.14 * Will the animals be taken to a different location for any procedures
ERIC Educational Resources Information Center
Levine, Elliott
2002-01-01
Strategies to help garner community support in school technology growth or maintenance include the following: (1) consider a "current state of technology" report; (2) forget five-year plans; (3) develop annual technology reports; (4) look to your website; (5) seek constructive opportunities to share technology, and (6) show off best examples at…
A kill curve for Phanerozoic marine species
NASA Technical Reports Server (NTRS)
Raup, D. M.
1991-01-01
A kill curve for Phanerozoic species is developed from an analysis of the stratigraphic ranges of 17,621 genera, as compiled by Sepkoski. The kill curve shows that a typical species' risk of extinction varies greatly, with most time intervals being characterized by very low risk. The mean extinction rate of 0.25/m.y. is thus a mixture of long periods of negligible extinction and occasional pulses of much higher rate. Because the kill curve is merely a description of the fossil record, it does not speak directly to the causes of extinction. The kill curve may be useful, however, to li inverted question markmit choices of extinction mechanisms.
Dissociative Recombination without a Curve Crossing
NASA Technical Reports Server (NTRS)
Guberman, Steven L.
1994-01-01
Ab initio calculations show that a curve crossing is not always needed for a high dissociative- recombination cross section. For HeH(+), in which no neutral states cross the ion potential curve, dissociative recombination is driven by the nuclear kinetic-energy operator on adiabatic potential curves. The kinetic-energy derivative operator allows for capture into repulsive curves that are outside of the classical turning points for the nuclear motion. The dominant dissociative route is the C (2)Sigma(+) state leading to H(n = 2) atoms. An analogous mechanism is proposed for the dissociative recombination of H3(+).
Double hysteresis loop in (Pb0.90La0.10)Ti0.975O3/Pb(Zr0.20Ti0.80)O3 bilayer thin films
NASA Astrophysics Data System (ADS)
Wu, Jiagang; Zhu, Jiliang; Xiao, Dingquan; Zhu, Jianguo
2007-11-01
(Pb0.90La0.10)Ti0.975O3/Pb(Zr0.20Ti0.80)O3 bilayer thin films were fabricated using radio frequency magnetron sputtering with a PbOx buffer layer. The x-ray diffraction patterns show that the bilayers possess highly (100) orientation. Polarization hysteresis and capacitance-voltage characteristics of the bilayers show clear antiferroelectric (AFE) characteristics. The related mechanism for double hysteresis loop was also discussed. The competition among the intrinsic ferroelectric coupling at the interface between bilayers gives rise to an AFE polarization behavior.
The effect of contact angle hysteresis on droplet motion and collisions on superhydrophobic surfaces
NASA Astrophysics Data System (ADS)
Nilsson, Michael; Rothstein, Jonathan
2010-11-01
The effect of varying the contact angle hysteresis of a superhydrophobic surface on the characteristics and dynamics of water droplet motion and their subsequent collision are investigated using a high-speed camera. The surfaces are created by imparting random roughness to Teflon through sanding. With this technique, it is possible to create surfaces with similar advancing contact angles near 150 degrees, but with varying contact angle hysteresis. This talk will focus on a number of interesting experimental observations pertaining to drop dynamics along a surface with uniform hysteresis, drop motion along surfaces with transition zones from one hysteresis to another, and the collision of droplets on surfaces of uniform hysteresis. For single drop studies, gravity is used as the driving force, while the collision studies use pressurized air to propel one drop into the other. For the case of droplet collision, the effect of hysteresis, Weber number, and impact number on the maximum deformation of the drops, and the post-collision dynamics will be discussed. For the single droplet measurements, the resistance to motion will be characterized as well as the transition from rolling to sliding as a function of drop size, inclination angle, and hysteresis. Additionally, we will quantify the effect of surface transitions on the resulting motion, mixing, and deflection of the drops.
Measuring Model Rocket Engine Thrust Curves
ERIC Educational Resources Information Center
Penn, Kim; Slaton, William V.
2010-01-01
This paper describes a method and setup to quickly and easily measure a model rocket engine's thrust curve using a computer data logger and force probe. Horst describes using Vernier's LabPro and force probe to measure the rocket engine's thrust curve; however, the method of attaching the rocket to the force probe is not discussed. We show how a…
NSDL National Science Digital Library
The Show-Me Center is a partnership of four NSF-sponsored middle grades mathematics curriculum development Satellite Centers (University of Wisconsin, Michigan State University, University of Montana, and the Educational Development Center). The group's website provides "information and resources needed to support selection and implementation of standards-based middle grades mathematics curricula." The Video Showcase includes segments on Number, Algebra, Geometry, Measure, and Data Analysis, with information on ways to obtain the complete video set. The Curricula Showcase provides general information, unit goals, sample lessons and teacher pages spanning four projects: the Connected Mathematics Project (CMP), Mathematics in Context (MiC), MathScape: Seeing and Thinking Mathematically, and Middle Grades Math Thematics. The website also posts Show-Me Center newsletters, information on upcoming conferences and workshops, and links to resources including published articles and unpublished commentary on mathematics school reform.
NSDL National Science Digital Library
2008-01-01
Come along as the folks at the University of Missouri show you the history of their college days through the Show Me magazine. It's a wonderful collection of college humor published from 1946 to 1963. First-time visitors would do well to read about the magazine's colorful past, courtesy of Jerry Smith. A good place to start is the November 1920 issue (easily found when you browse by date), which contains a number of parody advertisements along with some doggerels poking good natured fun at the football team and an assortment of deans. Also, it's worth noting that visitors can scroll through issues and save them to an online "bookbag" for later use.
NASA Technical Reports Server (NTRS)
2006-01-01
15 September 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a landslide that occurred off of a steep slope in Tithonium Chasma, part of the vast Valles Marineris trough system.
Location near: 4.8oS, 84.6oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Autumn
NSDL National Science Digital Library
2011-01-01
This lesson plan assesses student interpretation of graphs utilizing cooperative learning to further students understanding. Types of graphs used are horizontal and vertical bar graphs, picture graphs, and pictographs. In the lesson students play a game called the Graphing Game Show, in which they must work as a team to answer questions about specific graphs. The lesson includes four student resource worksheets and suggestions for extension and differentiation.
Lawhorn, D. Bruce
2006-10-13
? Vaccinating to prevent serious diseases ? Deworming the pigs routinely ? Having sick pigs promptly diagnosed and treated ? Using prescribed drugs properly Starting with healthy PigS To prevent disease outbreaks in show pigs, start by preparing before you.... Antibiotics are totally ineffective in preventing common viral diseases such as transmissible gas- troenteritis and swine influenza. Also, vaccines are not available for all swine diseases and must be giv- en long before the pigs undertake the rigors...
Mathematical Curve Conjectures
NSDL National Science Digital Library
James Rutledge
In this activity, a six-foot length of nylon rope is suspended at both ends to model a mathematical curve known as the hyperbolic cosine. In a write-pair-share activity, students are asked to make a conjecture concerning the nature of the curve and then embark on a guided discovery in which they attempt to determine a precise mathematical description of the curve using function notation.
SHIMURA AND TEICHM ULLER CURVES
Moeller, Martin
space of curves Mg that are both ShimuraÂ and TeichmË?uller curves: For both g = 3 and g = 4 there exists classes of curves. The proof of the classification relies on the geometry of squareÂtiled coverings. Introduction A TeichmË?uller curve is an algebraic curve C # M g in the moduli space of curves, which
Hysteresis of thin film IPRTs in the range 100 °C to 600 °C
NASA Astrophysics Data System (ADS)
Zvizdi?, D.; Šestan, D.
2013-09-01
As opposed to SPRTs, the IPRTs succumb to hysteresis when submitted to change of temperature. This uncertainty component, although acknowledged as omnipresent at many other types of sensors (pressure, electrical, magnetic, humidity, etc.) has often been disregarded in their calibration certificates' uncertainty budgets in the past, its determination being costly, time-consuming and not appreciated by customers and manufacturers. In general, hysteresis is a phenomenon that results in a difference in an item's behavior when approached from a different path. Thermal hysteresis results in a difference in resistance at a given temperature based on the thermal history to which the PRTs were exposed. The most prominent factor that contributes to the hysteresis error in an IPRT is a strain within the sensing element caused by the thermal expansion and contraction. The strains that cause hysteresis error are closely related to the strains that cause repeatability error. Therefore, it is typical that PRTs that exhibit small hysteresis also exhibit small repeatability error, and PRTs that exhibit large hysteresis have poor repeatability. Aim of this paper is to provide hysteresis characterization of a batch of IPRTs using the same type of thin-film sensor, encapsulated by same procedure and same company and to estimate to what extent the thermal hysteresis obtained by testing one single thermometer (or few thermometers) can serve as representative of other thermometers of the same type and manufacturer. This investigation should also indicate the range of hysteresis departure between IPRTs of the same type. Hysteresis was determined by cycling IPRTs temperature from 100 °C through intermediate points up to 600 °C and subsequently back to 100 °C. Within that range several typical sub-ranges are investigated: 100 °C to 400 °C, 100 °C to 500 °C, 100 °C to 600 °C, 300 °C to 500 °C and 300 °C to 600 °C . The hysteresis was determined at various temperatures by comparison calibration with SPRT. The results of investigation are presented in a graphical form for all IPRTs, ranges and calibration points.
The thermal hysteresis activity of the type I antifreeze protein: A statistical mechanics model
NASA Astrophysics Data System (ADS)
Li, Li-Fen; Liang, X. X.; Li, Q. Z.
2009-04-01
Based on the adsorption-inhibition theory, a statistical mechanics model is proposed to investigate the thermal hysteresis activity of the type I antifreeze protein. The thermal hysteresis activity is evaluated by determining the AFP molecule coverage rate on the ice surface and the Gibbs function of the system. As examples, the calculated results for the thermal hysteresis temperatures of AFP9, HPLC-6(TTTT) and AAAA2kE as functions of the concentration of the AFP solution are obtained and discussed. The theoretical results are in agreement with the experimental data.
Numerical analysis of a measured efficiency hysteresis on a bulb turbine model
NASA Astrophysics Data System (ADS)
Houde, S.; Carrier, A.; Buron, J. D.; Deschênes, C.
2014-03-01
Within the framework of the BulbT project, simulations were performed to understand the origin of a measured hysteresis on the efficiency hill chart of a bulb turbine model. This hysteresis is associated with a sharp drop of efficiency located at slightly higher discharge than the best efficiency operating condition. It appears as a variation in the turbine performance whether an operating condition located in the efficiency drop is reached from a lower or a higher discharge. This hysteresis was reproduced numerically using Reynolds Averaged Navier Stokes (RANS) simulations. The paper presents the experimental results, the numerical methodology and a comprehensive analysis of the simulations to shed light on this interesting phenomenon.
Geomorphological origin of recession curves
NASA Astrophysics Data System (ADS)
Biswal, Basudev; Marani, Marco
2010-12-01
We identify a previously undetected link between the river network morphology and key recession curves properties through a conceptual-physical model of the drainage process of the riparian unconfined aquifer. We show that the power-law exponent, ?, of -dQ/dt vs. Q curves is related to the power-law exponent of N(l) vs. G(l) curves (which we show to be connected to Hack's law), where l is the downstream distance from the channel heads, N(l) is the number of channel reaches exactly located at a distance l from their channel head, and G(l) is the total length of the network located at a distance greater or equal to l from channel heads. Using Digital Terrain Models and daily discharge observations from 67 US basins we find that geomorphologic ? estimates match well the values obtained from recession curves analyses. Finally, we argue that the link between recession flows and network morphology points to an important role of low-flow discharges in shaping the channel network.
Education Statistics Slide Show
NSDL National Science Digital Library
Created by Grace York, coordinator of the University of Michigan's Documents Center, the Education Statistics Slide Show is an online presentation demonstrating how to locate, obtain, and manipulate educational data on the Web. The presentation consists of 72 slides and offers instruction on the use of several Websites including the US Census Bureau's American Factfinder site (see the April 2, 1999 Scout Report), the Center for International Earth Science Information Network (CIESIN) Census Mapping site, the National Center for Education Statistics (NCES) site, the FEDSTATS site (see the May 30, 1997 Scout Report), and many more. The tutorial presentation also provides ten practice questions and a detailed Webliography.
NASA Astrophysics Data System (ADS)
Ahrenholz, B.; Tölke, J.; Lehmann, P.; Peters, A.; Kaestner, A.; Krafczyk, M.; Durner, W.
2008-09-01
In this work we use two numerical methods which rely only on the geometry and material parameters to predict capillary hysteresis in a porous material. The first numerical method is a morphological pore network (MPN) model, where structural elements are inserted into the imaged pore space to quantify the local capillary forces. Then, based on an invasion-percolation mechanism, the fluid distribution is computed. The second numerical method is a lattice-Boltzmann (LB) approach which solves the coupled Navier-Stokes equations for both fluid phases and describes the dynamics of the fluid/fluid interface. We have developed an optimized version of the model proposed in [Tölke J, Freudiger S, Krafczyk M. An adaptive scheme for LBE multiphase flow simulations on hierarchical grids, Comput. Fluids 2006;35:820-30] for the type of flow problems encountered in this work. A detailed description of the model and an extensive validation of different multiphase test cases have been carried out. We investigated pendular rings in a sphere packing, static and dynamic capillary bundle models and the residual saturation in a sphere packing. A sample of 15 mm in diameter filled with sand particles ranging from 100 to 500 ?m was scanned using X-rays from a synchrotron source with a spatial resolution of 11 ?m. Based on this geometry we computed the primary drainage, the first imbibition and the secondary drainage branch of the hysteresis loop using both approaches. For the LB approach, we investigated the dependence of the hysteresis loop on the speed of the drainage and the imbibition process. Furthermore we carried out a sensitivity analysis by simulating the hysteretic effect in several subcubes of the whole geometry with extremal characteristic properties. The predicted hysteretic water retention curves were compared to the results of laboratory experiments using inverse modeling based on the Richards equation. A good agreement for the hysteresis loop between the LB and MPN model has been obtained. The primary and secondary drainage of the hysteresis loop of the LB and MPN model compare very well, and also the experimental results fit well with a slight offset of 10% in the amplitude. Differences for the first imbibition have been observed, but also large differences between two different experimental runs have been observed.
Diao, Rui; Fan, Chunyan; Do, D D; Nicholson, D
2015-12-15
The adsorption and desorption of Kr on graphite at temperatures in the range 60-88K, was systematically investigated using a combination of several simulation techniques including: Grand Canonical Monte Carlo (GCMC), Canonical kinetic-Monte Carlo (C-kMC) and the Mid-Density Scheme (MDS). Particular emphasis was placed on the gas-solid, gas-liquid and liquid-solid 2D phase transitions. For temperatures below the bulk triple point, the transition from a 2D-liquid-like monolayer to a 2D-solid-like state is manifested as a sub-step in the isotherm. A further increase in the chemical potential leads to another rearrangement of the 2D-solid-like state from a disordered structure to an ordered structure that is signalled by (1) another sub-step in the monolayer region and (2) a spike in the plot of the isosteric heat versus density at loadings close to the dense monolayer coverage concentration. Whenever a 2D transition occurs in a grand canonical isotherm it is always associated with a hysteresis, a feature that is not widely recognised in the literature. We studied in details this hysteresis with the analysis of the canonical isotherm, obtained with C-kMC, which exhibits a van der Waals (vdW) type loop with a vertical segment in the middle. We complemented the hysteresis loop and the vdW curve with the analysis of the equilibrium transition obtained with the MDS, and found that the equilibrium transition coincides exactly with the vertical segment of the C-kMC isotherm, indicating the co-existence of two phases at equilibrium. We also analysed adsorption at higher layers and found that the 2D-coexistence is also observed, provided that the temperature is well below the triple point. Finally the 2D-critical temperatures were obtained for the first three layers and they are in good agreement with the experimental data in the literature. PMID:26364074
7 CFR 43.105 - Operating characteristics (OC) curves.
Code of Federal Regulations, 2010 CFR
2010-01-01
...CONTAINER REGULATIONS STANDARDS FOR SAMPLING PLANS Sampling Plans § 43.105 Operating characteristics (OC) curves. The OC curves shows the ability of the various sampling plans, presented for each AQL, to distinguish...
NSDL National Science Digital Library
"Egg is a new TV show about people making art across America" from PBS. This accompanying Website presents excerpts from sixteen episodes of the series, with three more "hatching soon," such as Close to Home, profiling three photographers: Jeanine Pohlhaus, whose pictures document her father's struggle with mental illness; Gregory Crewdson's photos of Lee, Massachusetts; and Joseph Rodriguez's photos of Hispanics in New York City. Excerpts include video clips, gallery listings where the artists' work can be seen, and short interviews with artists. Some episodes also offer "peeps," glimpses of material not shown on TV, such as the Space episode's peep, Shooting Stars, that provides directions for astrophotography, taking photographs of star trails. Other sections of the site are airdates, for local listings; see and do usa, where vacationers can search for art events at their destinations; and egg on the arts, a discussion forum.
Jia, Xin; Zha, Tianshan; Wu, Bin; Zhang, Yuqing; Chen, Wenjing; Wang, Xiaoping; Yu, Haiqun; He, Guimei
2013-01-01
Although the temperature response of soil respiration (Rs) has been studied extensively, several issues remain unresolved, including hysteresis in the Rs–temperature relationship and differences in the long- vs. short-term Rs sensitivity to temperature. Progress on these issues will contribute to reduced uncertainties in carbon cycle modeling. We monitored soil CO2 efflux with an automated chamber system in a Pinus tabulaeformis plantation near Beijing throughout 2011. Soil temperature at 10-cm depth (Ts) exerted a strong control over Rs, with the annual temperature sensitivity (Q10) and basal rate at 10°C (Rs10) being 2.76 and 1.40 µmol m?2 s?1, respectively. Both Rs and short-term (i.e., daily) estimates of Rs10 showed pronounced seasonal hysteresis with respect to Ts, with the efflux in the second half of the year being larger than that early in the season for a given temperature. The hysteresis may be associated with the confounding effects of microbial population dynamics and/or litter input. As a result, all of the applied regression models failed to yield unbiased estimates of Rs over the entire annual cycle. Lags between Rs and Ts were observed at the diel scale in the early and late growing season, but not in summer. The seasonality in these lags may be due to the use of a single Ts measurement depth, which failed to represent seasonal changes in the depth of CO2 production. Daily estimates of Q10 averaged 2.04, smaller than the value obtained from the seasonal relationship. In addition, daily Q10 decreased with increasing Ts, which may contribute feedback to the climate system under global warming scenarios. The use of a fixed, universal Q10 is considered adequate when modeling annual carbon budgets across large spatial extents. In contrast, a seasonally-varying, environmentally-controlled Q10 should be used when short-term accuracy is required. PMID:23469089
Jia, Xin; Zha, Tianshan; Wu, Bin; Zhang, Yuqing; Chen, Wenjing; Wang, Xiaoping; Yu, Haiqun; He, Guimei
2013-01-01
Although the temperature response of soil respiration (Rs ) has been studied extensively, several issues remain unresolved, including hysteresis in the Rs -temperature relationship and differences in the long- vs. short-term Rs sensitivity to temperature. Progress on these issues will contribute to reduced uncertainties in carbon cycle modeling. We monitored soil CO2 efflux with an automated chamber system in a Pinus tabulaeformis plantation near Beijing throughout 2011. Soil temperature at 10-cm depth (Ts ) exerted a strong control over Rs , with the annual temperature sensitivity (Q10) and basal rate at 10°C (Rs10) being 2.76 and 1.40 µmol m(-2) s(-1), respectively. Both Rs and short-term (i.e., daily) estimates of Rs10 showed pronounced seasonal hysteresis with respect to Ts , with the efflux in the second half of the year being larger than that early in the season for a given temperature. The hysteresis may be associated with the confounding effects of microbial population dynamics and/or litter input. As a result, all of the applied regression models failed to yield unbiased estimates of Rs over the entire annual cycle. Lags between Rs and Ts were observed at the diel scale in the early and late growing season, but not in summer. The seasonality in these lags may be due to the use of a single Ts measurement depth, which failed to represent seasonal changes in the depth of CO2 production. Daily estimates of Q10 averaged 2.04, smaller than the value obtained from the seasonal relationship. In addition, daily Q10 decreased with increasing Ts , which may contribute feedback to the climate system under global warming scenarios. The use of a fixed, universal Q10 is considered adequate when modeling annual carbon budgets across large spatial extents. In contrast, a seasonally-varying, environmentally-controlled Q10 should be used when short-term accuracy is required. PMID:23469089
Holomorphic curves in surfaces of general type.
Lu, S S; Yau, S T
1990-01-01
This note answers some questions on holomorphic curves and their distribution in an algebraic surface of positive index. More specifically, we exploit the existence of natural negatively curved "pseudo-Finsler" metrics on a surface S of general type whose Chern numbers satisfy c(2)1>2c2 to show that a holomorphic map of a Riemann surface to S whose image is not in any rational or elliptic curve must satisfy a distance decreasing property with respect to these metrics. We show as a consequence that such a map extends over isolated punctures. So assuming that the Riemann surface is obtained from a compact one of genus q by removing a finite number of points, then the map is actually algebraic and defines a compact holomorphic curve in S. Furthermore, the degree of the curve with respect to a fixed polarization is shown to be bounded above by a multiple of q - 1 irrespective of the map. PMID:11607050
Scintillation Caustics in Planetary Occultation Light Curves
Cooray, A R; Cooray, Asantha R.
2003-01-01
We revisit the GSC5249-01240 light curve obtained during its occultation by Saturn's North polar region. In addition to refractive scintillations, the power spectrum of intensity fluctuations shows an enhancement of power between refractive and diffractive regimes. We identify this excess power as due to high amplitude spikes in the light curve and suggest that these spikes are due to caustics associated with ray crossing situations. The flux variation in individual spikes follows the expected caustic behavior, including diffraction fringes which we have observed for the first time in a planetary occultation light curve. The presence of caustics in scintillation light curves require an inner scale cut off to the power spectrum of underlying density fluctuations associated with turbulence. Another possibility is the presence of gravity waves in the atmosphere. While occultation light curves previously showed the existence of refractive scintillations, a combination of small projected stellar size and a low rel...
ERIC Educational Resources Information Center
Nordmark, Arne; Essen, Hanno
2007-01-01
The equilibrium of a flexible inextensible string, or chain, in the centrifugal force field of a rotating reference frame is investigated. It is assumed that the end points are fixed on the rotation axis. The shape of the curve, the skipping rope curve or "troposkien", is given by the Jacobi elliptic function sn. (Contains 3 figures.)
Pairings on hyperelliptic curves
Balakrishnan, Jennifer; Chisholm, Sarah; Eisentraeger, Kirsten; Stange, Katherine; Teske, Edlyn
2009-01-01
We assemble and reorganize the recent work in the area of hyperelliptic pairings: We survey the research on constructing hyperelliptic curves suitable for pairing-based cryptography. We also showcase the hyperelliptic pairings proposed to date, and develop a unifying framework. We discuss the techniques used to optimize the pairing computation on hyperelliptic curves, and present many directions for further research.
Anodic Polarization Curves Revisited
ERIC Educational Resources Information Center
Liu, Yue; Drew, Michael G. B.; Liu, Ying; Liu, Lin
2013-01-01
An experiment published in this "Journal" has been revisited and it is found that the curve pattern of the anodic polarization curve for iron repeats itself successively when the potential scan is repeated. It is surprising that this observation has not been reported previously in the literature because it immediately brings into…
NSDL National Science Digital Library
Hill, David R.
2003-02-24
Take a solid cube with rods attached at diagonally opposite vertices. Hold the rods horizontally and rapidly spin the cube. (See Figure 1.) You should see a curved outline formed by the spinning cube. The objective of this demos is to discover how the straight edges of the cube become curved. The demo is physically based, but can be simulated within various software packages.
Galilean Classification of Curves
Mehdi Nadjafikhah; Ali Mahdipour Shirayeh
2007-11-13
In this paper, we classify space-time curves up to Galilean group of transformations with Cartan's method of equivalence. As an aim, we elicit invariats from action of special Galilean group on space-time curves, that are, in fact, conservation laws in physics. We also state a necessary and sufficient condition for equivalent Galilean motions.
Walusinski, Olivier
2014-01-01
In the second half of the 19th century, Jean-Martin Charcot (1825-1893) became famous for the quality of his teaching and his innovative neurological discoveries, bringing many French and foreign students to Paris. A hunger for recognition, together with progressive and anticlerical ideals, led Charcot to invite writers, journalists, and politicians to his lessons, during which he presented the results of his work on hysteria. These events became public performances, for which physicians and patients were transformed into actors. Major newspapers ran accounts of these consultations, more like theatrical shows in some respects. The resultant enthusiasm prompted other physicians in Paris and throughout France to try and imitate them. We will compare the form and substance of Charcot's lessons with those given by Jules-Bernard Luys (1828-1897), Victor Dumontpallier (1826-1899), Ambroise-Auguste Liébault (1823-1904), Hippolyte Bernheim (1840-1919), Joseph Grasset (1849-1918), and Albert Pitres (1848-1928). We will also note their impact on contemporary cinema and theatre. PMID:25273491
NASA Astrophysics Data System (ADS)
Jordanova, Diana; Jordanova, Neli; Hoffmann, Viktor
2006-03-01
The use of magnetic susceptibility as a proxy for the relative degree of industrial pollution of soils and sediments is only qualitative and complications arise when unmixing the contributions from different sources. Detailed characterization of anthropogenic magnetic phases is needed in order to discriminate the input from different sources. The present study investigates magnetic fractions from fly ashes from different thermoelectric power plants and lagooned ash from metal works in Bulgaria, to further our knowledge of potential sources. Thermomagnetic analysis of saturation magnetization ( Ms) and magnetic susceptibility ( K) revealed a low-substituted magnetite-like phase in power-plant fly ashes and magnetite/maghemite phases in lagooned ash. Magnetic hysteresis measurements on single spherules from the wastes are combined with subsequent SEM/EDX examination of the same grains, allowing for the grain size dependence of the hysteresis parameters to be directly obtained for the studied anthropogenic phases. The results suggest that the structure-sensitive magnetic parameters for the lagooned ash show stronger size dependence compared to the published data for synthetic crushed magnetites, which is due to the complex internal structure and stress level in the anthropogenic phases formed under fast cooling conditions. Moreover, the Day plot for the studied single grains shows the presence of different correlation lines for fly ashes and the lagooned ash, i.e. it discriminates between the sources.
Physical interpretation of hysteresis loops: Micromagnetic modeling of fine particle magnetite
NASA Astrophysics Data System (ADS)
Tauxe, Lisa; Bertram, H. Neal; Seberino, Christian
2002-10-01
Hysteresis measurements have become an important part of characterizing magnetic behavior of rocks in paleomagnetic studies. Theoretical interpretation is often difficult owing to the complexity of mineral magnetism and published data sets demonstrate remanence and coercivity behavior that is currently unexplained. In the last decade, numerical micromagnetic modeling has been used to simulate magnetic particles. Such simulations reveal the existence of nonuniform remanent states between single and multidomain, known as the "flower" and "vortex" configurations. These suggest plausible explanations for many hysteresis measurements yet fall short of explaining high saturation remanence, high coercivity data such as those commonly observed in fine grained submarine basalts. In this paper, we review the theoretical and experimental progress to date in understanding hysteresis of geological materials. We extend numerical simulations to a greater variety of shapes and sizes, including random assemblages of particles and shapes more complex than simple rods and cubes. Our simulations provide plausible explanations for a wide range of hysteresis behavior.
NASA Astrophysics Data System (ADS)
Yasunobu, Tsuyoshi; Matsuoka, Ken; Kashimura, Hideo; Matsuo, Shigeru; Setoguchi, Toshiaki
2006-09-01
When the high-pressure gas is exhausted to the vacuum chamber from the supersonic nozzle, the overexpanded supersonic jet is formed at specific condition. In two-dimensional supersonic jet, furthermore, it is known that the hysteresis phenomena for the reflection type of shock wave in the flow field is occurred under the quasi-steady flow and for instance, the transitional pressure ratio between the regular reflection (RR) and Mach reflection (MR) is affected by this phenomenon. Many papers have described the hysteresis phenomena for underexpanded supersonic jet, but this phenomenon under the overexpanded axisymmetric jet has not been detailed in the past papers. The purpose of this study is to clear the hysteresis phenomena for the reflection type of shock wave at the overexpanded axisymmetric jet using the TVD method and to discuss the characteristic of hysteresis phenomena.
Capillary Condensation Hysteresis in Overlapping Spherical Pores: A Monte Carlo Simulation Study
Muzzio, Fernando J.
Capillary Condensation Hysteresis in Overlapping Spherical Pores: A Monte Carlo Simulation Study Carlo simulation study of capillary condensation and evaporation cycles in the course of Lennard pore: capillary condensation takes place upon achieving the limit of stability of adsorption film
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.
IEEE Transactions on Automation Science and Engineering Compensation of Scanner Creep and Hysteresis
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
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.
NASA Astrophysics Data System (ADS)
Campbell, G. S.; Campbell, C. S.; Cobos, D. R.
2008-12-01
Soil moisture release curves (MRC) or moisture sorption isotherms, which relate the amount of water in soil to its water potential or water activity, have many applications in soil physics and geotechnical engineering including determining soil water flow, specific surface area, swelling potential, and clay mineralogy and activity. Although research showing MRC for various soils dates back more than 50 years, limitations with the measurement technique have made developing MRC time consuming and inaccurate, especially in dry soils. Recently, an instrument was developed to create moisture sorption isotherms for various food and pharmaceutical products. The objective of this research was to investigate its use in soils for obtaining MRC in dry soils simply and accurately. Several different soil types were tested in the instrument from pure sand to bentonite and smectite clays. From the MRC of these soils, we were able to develop good correlations between actual and derived clay activity, surface area, and swelling potential. In addition, we were able to see hysteresis in dry soil water uptake for all soils, including sand. According to our tests, this new instrument will provide a powerful tool to investigate several soil physical properties simply and accurately.
Large thermal hysteresis for iron(II) spin crossover complexes with N-(pyrid-4-yl)isonicotinamide.
Lochenie, Charles; Bauer, Wolfgang; Railliet, Antoine P; Schlamp, Stephan; Garcia, Yann; Weber, Birgit
2014-11-01
A new series of iron(II) 1D coordination polymers with the general formula [FeL1(pina)]·xsolvent with L1 being a tetradentate N2O2(2-) coordinating Schiff-base-like ligand [([3,3']-[1,2-phenylenebis(iminomethylidyne)]bis(2,4-pentanedionato)(2-)-N,N',O(2),O(2)'], and pina being a bridging axial ligand N-(pyrid-4-yl)isonicotinamide, are discussed. The X-ray crystal structure of [FeL1(pina)]·2MeOH was solved for the low-spin state. The compound crystallizes in the monoclinic space group P21/c, and the analysis of the crystal packing reveals the formation of a hydrogen bond network where additional methanol molecules are included. Different magnetic properties are observed for the seven samples analyzed, depending on the nature of the included solvent molecules. The widest hysteresis loop is observed for a fine crystalline sample of composition [FeL1(pina)]·xH2O/MeOH. The 88 K wide thermal hysteresis loop (T1/2? = 328 K and T1/2? = 240 K) is centered around room temperature and can be repeated without of a loss of the spin transition properties. For the single crystals of [FeL1(pina)]·2MeOH, a 51 K wide hysteresis loop is observed (T1/2? = 296 K and T1/2? = 245 K) that is also stable for several cycles. For a powder sample of [FeL1(pina)]·0.5H2O·0.5MeOH a cooperative spin transition with a 46 K wide hysteresis loop around room temperature is observed (T1/2? = 321 K and T1/2? = 275 K). This compound was further investigated using Mössbauer spectroscopy and DSC. Both methods reveal that, in the cooling mode, the spin transition is accompanied by a phase transition while in the heating mode a loss of the included methanol is observed that leads to a loss of the spin transition properties. These results show that the pina ligand was used successfully in a crystal-engineering-like approach to generate 1D coordination polymers and improve their spin crossover properties. PMID:25314334
Stretched View Showing 'Victoria'
NASA Technical Reports Server (NTRS)
2006-01-01
[figure removed for brevity, see original site] Stretched View Showing 'Victoria'
This pair of images from the panoramic camera on NASA's Mars Exploration Rover Opportunity served as initial confirmation that the two-year-old rover is within sight of 'Victoria Crater,' which it has been approaching for more than a year. Engineers on the rover team were unsure whether Opportunity would make it as far as Victoria, but scientists hoped for the chance to study such a large crater with their roving geologist. Victoria Crater is 800 meters (nearly half a mile) in diameter, about six times wider than 'Endurance Crater,' where Opportunity spent several months in 2004 examining rock layers affected by ancient water.
When scientists using orbital data calculated that they should be able to detect Victoria's rim in rover images, they scrutinized frames taken in the direction of the crater by the panoramic camera. To positively characterize the subtle horizon profile of the crater and some of the features leading up to it, researchers created a vertically-stretched image (top) from a mosaic of regular frames from the panoramic camera (bottom), taken on Opportunity's 804th Martian day (April 29, 2006).
The stretched image makes mild nearby dunes look like more threatening peaks, but that is only a result of the exaggerated vertical dimension. This vertical stretch technique was first applied to Viking Lander 2 panoramas by Philip Stooke, of the University of Western Ontario, Canada, to help locate the lander with respect to orbiter images. Vertically stretching the image allows features to be more readily identified by the Mars Exploration Rover science team.
The bright white dot near the horizon to the right of center (barely visible without labeling or zoom-in) is thought to be a light-toned outcrop on the far wall of the crater, suggesting that the rover can see over the low rim of Victoria. In figure 1, the northeast and southeast rims are labeled in bright green. Finally, the light purple lines and arrow highlight a small crater.
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.
Does Corneal Hysteresis Correlate with Endothelial Cell Density?
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
The Dynamic Characteristic and Hysteresis Effect of an Air Spring
NASA Astrophysics Data System (ADS)
Löcken, F.; Welsch, M.
2015-02-01
In many applications of vibration technology, especially in chassis, air springs present a common alternative to steel spring concepts. A design-independent and therefore universal approach is presented to describe the dynamic characteristic of such springs. Differential and constitutive equations based on energy balances of the enclosed volume and the mountings are given to describe the nonlinear and dynamic characteristics. Therefore all parameters can be estimated directly from physical and geometrical properties, without parameter fitting. The numerically solved equations fit very well to measurements of a passenger car air spring. In a second step a simplification of this model leads to a pure mechanical equation. While in principle the same parameters are used, just an empirical correction of the effective heat transfer coefficient is needed to handle some simplification on this topic. Finally, a linearization of this equation leads to an analogous mechanical model that can be assembled from two common spring- and one dashpot elements in a specific arrangement. This transfer into "mechanical language" enables a system description with a simple force-displacement law and a consideration of the nonobvious hysteresis and stiffness increase of an air spring from a mechanical point of view.
Magnetization and Hysteresis of Dilute Magnetic-Oxide Nanoparticles
NASA Astrophysics Data System (ADS)
Skomski, Ralph; Balamurugan, B.; Sellmyer, D. J.
2014-03-01
Real-structure imperfections in dilute magnetic oxides tend to create small concentrations of local magnetic moments that are coupled by fairly long-range exchange interactions, mediated by p-electrons. The robustness of these interactions is caused by the strong overlap of the p orbitals, as contrasted to the much weaker interatomic exchange involving iron-series 3d electrons. The net exchange between defect moments can be positive or negative, which gives rise to spin structures with very small net moments. Similarly, the moments exhibit magnetocrystalline anisotropy, reinforced by electron hopping to and from 3d states and generally undergoing some random-anuisotropy averaging. Since the coercivity scales as 2K1/M and M is small, this creates pronounced and -- in thin films -- strongly anisotropic hysteresis loops. In finite systems with N moments, both K1 and M are reduced by a factor of order N1/2 due to random anisotropy and moment compensation, respectively, so that that typical coercivities are comparable to bulk magnets. Thermal activation readily randomizes the net moment of small oxide particles, so that the moment is easier to measure in compacted or aggregated particle ensembles. This research is supported by DOE (BES).
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.
On growth rate hysteresis and catastrophic crystal growth
NASA Astrophysics Data System (ADS)
Ferreira, Cecília; Rocha, Fernando A.; Damas, Ana M.; Martins, Pedro M.
2013-04-01
Different crystal growth rates as supersaturation is increasing or decreasing in impure media is a phenomenon called growth rate hysteresis (GRH) that has been observed in varied systems and applications, such as protein crystallization or during biomineralization. We have recently shown that the transient adsorption of impurities onto newly formed active sites for growth (or kinks) is sensitive to the direction and rate of supersaturation variation, thus providing a possible explanation for GRH [6]. In the present contribution, we expand on this concept by deriving the analytical expressions for transient crystal growth based on the energetics of growth hillock formation and kink occupation by impurities. Two types of GRH results are described according to the variation of kink density with supersaturation: for nearly constant density, decreasing or increasing supersaturation induce, respectively, growth promoting or inhibiting effects relative to equilibrium conditions. This is the type of GRH measured by us during the crystallization of egg-white lysozyme. For variable kink density, slight changes in the supersaturation level may induce abrupt variations in the crystal growth rate. Different literature examples of this so-called 'catastrophic' crystal growth are discussed in terms of their fundamental consequences.
Breakpoint chlorination curves of greywater.
March, J G; Gual, M
2007-08-01
A study on chlorination of raw greywater with hypochlorite is reported in this paper. Samples were chlorinated in a variety of conditions, and residual chlorine (Cl2) was measured spectrophotometrically. For each sample, the chlorination curve (chlorine residuals versus chlorine dose) was obtained. Curves showed the typical hump-and-dip profile attributable to the formation and destruction of chloramines. It was observed that, after reactions with strong reductants and chloramines-forming compounds, the remaining organic matter exerted a certain demand of chlorine. The evolution of chlorination curves with addition of ammonia and dodecylbencene sulfonate sodium salt and with dilution of the greywater sample were studied. In addition, chlorination curves at several contact times have been obtained, resulting in slower chlorine decay in the hump zone than in the dip zone. In addition, the decay of coliforms in chlorinated samples was also investigated. It was found that, for a chlorination dosage corresponding to the maximum of the hump zone (average 8.9 mg Cl2/ L), samples were negative in coliforms after 10 to 30 minutes of contact time. After-growth was not observed within 3 days after chlorination. Implications in chlorination treatments of raw greywater can be derived from these results. PMID:17824528
Unit II-4 Curve fitting 1 Curve-fitting
Birkett, Stephen
Unit II-4 Curve fitting 1 Unit II-4 Curve-fitting Unit II-4 Curve fitting 2 Curve fitting vs interpolation Â· both find a function which approximates a set of data points Â curve fitting smooths globally Â interpolation smooths locally Â· statistics can quantify the relationship between the fit and errors in data
Hysteresis Effects and Strain-Induced Homogeneity Effects in Base Metal Thermocouples
NASA Astrophysics Data System (ADS)
Pavlasek, P.; Elliott, C. J.; Pearce, J. V.; Duris, S.; Palencar, R.; Koval, M.; Machin, G.
2015-03-01
Thermocouples are used in a wide variety of industrial applications in which they play an important role for temperature control and monitoring. Wire inhomogeneity and hysteresis effects are major sources of uncertainty in thermocouple measurements. To efficiently mitigate these effects, it is first necessary to explore the impact of strain-induced inhomogeneities and hysteresis, and their contribution to the uncertainty. This article investigates homogeneity and hysteresis effects in Types N and K mineral-insulated metal-sheathed (MIMS) thermocouples. Homogeneity of thermocouple wires is known to change when mechanical strain is experienced by the thermoelements. To test this influence, bends of increasingly small radii, typical in industrial applications, were made to a number of thermocouples with different sheath diameters. The change in homogeneity was determined through controlled immersion of the thermocouple into an isothermal liquid oil bath at and was found to be very small at for Type K thermocouples, with no measureable change in Type N thermocouples found. An experiment to determine the hysteresis effect in thermocouples was performed on swaged, MIMS Type N and Type K thermocouples, in the temperature range from to . The hysteresis measurements presented simulate the conditions that thermocouples may be exposed to in industrial applications through continuous cycling over 136 h. During this exposure, a characteristic drift from the reference function has been observed but no considerable difference between the heating and cooling measurements was measureable. The measured differences were within the measurement uncertainties; therefore, no hysteresis was observed.
Effect of hysteresis on the stability of an embankment under transient seepage
NASA Astrophysics Data System (ADS)
Liu, K.; Vardon, P. J.; Arnold, P.; Hicks, M. A.
2015-09-01
Hysteresis is a well-known phenomenon that exists in the soil water retention behaviour of unsaturated soils. However, there is little research on the effects of hysteresis on slope stability. If included in slope stability analyses, commonly the suction in the unsaturated zone is taken as non-hysteretic. In this paper, the authors investigate the effect of hysteresis on the stability of an embankment under transient seepage. A scenario of water level fluctuation has been assessed, in which a cyclic external water level fluctuates between a low and high level. It was found that the factor of safety (FOS), the volumetric water content and the suction in the unsaturated zone are significantly affected by hysteresis. It was also found that, when the period of water level fluctuation in one cycle is relatively small, there is little difference in the FOS between the hysteretic case and non-hysteretic case. However, when the period exceeds a certain threshold value, significant differences between these two cases can be observed. Compared to the case in which hysteresis is considered, the FOS is higher in the case which does not consider hysteresis. This suggests that the non-hysteretic case may overestimate slope stability, leading to a potentially dangerous situation. Moreover, the period under which there emerge large differences between the hysteretic and non-hysteretic case is strongly related to the magnitude of hydraulic conductivity and the period of the cyclic water level fluctuation.
NASA Astrophysics Data System (ADS)
Lee, Jae-Hoon; Park, Sang-Geun; Han, Sang-Myeon; Han, Min-Koo; Park, Kee-Chan
2008-03-01
New PMOS LTPS (low temperature polycrystalline silicon)-thin film transistor (TFT) pixel circuit, which can suppress an OLED current error caused by the hysteresis of LTPS-TFT for active matrix organic light emitting diode (AMOLED) display, is proposed and fabricated. The proposed pixel circuit employs a reset voltage driving so that the sweep direction of gate voltage in the current driving TFT is not altered by the gate voltage in the previous frame. Our experimental results show that OLED current error of the proposed pixel is successfully suppressed because a reset voltage can enable the starting gate voltage for a desired one not to be varied, while that of the conventional 2-TFT pixel exceeds over 15% due to the hysteresis of LTPS-TFT.
Mallonee, Ethel Wallace
1915-01-01
curves and were named by Rene de Saussure. Euler (1750) had investigated these curves but he did not recognize them as roulettes. There are two kinds of psuedo- cycloidals: (1) the paracycloid is generated by the rol ling of an imaginary circle upon a... of whose axes coincides with the x axis. The equation of the conic may be put into the form « >) dy y = ax + b. Row from the equations & = x+y&x » P d
Nagaraj, Vijayalakshmi H.; Mukhopadhyay, Swagatam; Dayarian, Adel; Sengupta, Anirvan M.
2014-01-01
In addition to gene network switches, local epigenetic modifications to DNA and histones play an important role in all-or-none cellular decision-making. Here, we study the dynamical design of a well-characterized epigenetic chromatin switch: the yeast SIR system, in order to understand the origin of the stability of epigenetic states. We study hysteresis in this system by perturbing it with a histone deacetylase inhibitor. We find that SIR silencing has many characteristics of a non-linear bistable system, as observed in conventional genetic switches, which are based on activities of a few promoters affecting each other through the abundance of their gene products. Quite remarkably, our experiments in yeast telomeric silencing show a very distinctive pattern when it comes to the transition from bistability to monostability. In particular, the loss of the stable silenced state, upon increasing the inhibitor concentration, does not seem to show the expected saddle node behavior, instead looking like a supercritical pitchfork bifurcation. In other words, the ‘off’ state merges with the ‘on’ state at a threshold concentration leading to a single state, as opposed to the two states remaining distinct up to the threshold and exhibiting a discontinuous jump from the ‘off’ to the ‘on’ state. We argue that this is an inevitable consequence of silenced and active regions coexisting with dynamic domain boundaries. The experimental observations in our study therefore have broad implications for the understanding of chromatin silencing in yeast and beyond. PMID:25536038
Rajratan Basu; Germano S. Iannacchione
2009-08-07
The self-organizing properties of nematic liquid crystals (LC) can be used to template carbon nanotubes (CNTs) on a macroscopic dimension. The nematic director field, coupled to the dispersed CNT long-axis, enables controlled director reorientation using well-established methods of LC alignment techniques, such as patterned-electrode-surface, electric fields, and magnetic fields. Electric field induced director rotation of a nematic LC+CNT system is of potential interests due to its possible applications as a nano electromechanical system. The relaxation mechanism for a LC+CNT composite, on the removal of the applied field, reveals the intrinsic dynamics of this anisotropic system. Dielectric hysteresis and temperature dependence of the dielectric constant coherently shows the ferroelectric-type behavior of the LC+CNT system in the nematic phase. The strong surface anchoring of LC molecules on CNT walls results in forming local isolated pseudo-nematic domains in the isotropic phase. These domains, being anisotropic, respond to external fields, but, do not relax back to the original state on switching of the field off, showing non-volatile memory effect.
NASA Astrophysics Data System (ADS)
Barnard, Daniel J.; Hsu, David K.
2011-06-01
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.
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.
Learning Curves in Manufacturing.
ERIC Educational Resources Information Center
Argote, Linda; Epple, Dennis
1990-01-01
Large increases in productivity are typically realized as organization gain experience in production. Examined is evidence from several disciplines on organizational learning curves. Reasons why organizational learning rates vary are identified. (YP)
Langley
2009-01-01
fast food worker. The last grouping includes "La Familia" and "Fast Sunday." The former concerns a middle-aged teacher's failed attempts to save a wayward student and her bitter regret when he does not graduate; the latter is about a twelve-year-old boy...
"Universal" Recession Curves and their Geomorphological Roots
NASA Astrophysics Data System (ADS)
Marani, M.; Biswal, B.
2011-12-01
The basic structural organization of channel networks, and of the connected hillslopes, have been shown to be intimately linked to basin responses to rainfall events, leading to geomorphological theories of the hydrologic response. Here, We identify a previously undetected link between the river network morphology and key recession curves properties. We show that the power-law exponent of -dQ/dt vs. Q curves is related to the power-law exponent of N(l) vs. G(l) curves (which we show to be connected to Hack's law), where l is the downstream distance from the channel heads, N(l) is the number of channel reaches exactly located at a distance l from their channel head, and G(l) is the total length of the network located at a distance greater or equal to l from channel heads. We then generalize the power-law expressions of recession curves, to identify "universal" curves, independent of the initial moisture conditions and of basin area, by making the -dQ/dt vs. Q curve non-dimensional using an index discharge representative of initial moisture conditions. We subsequently rescale the geomorphic recession curve, N(l) vs. G(l), producing a collapse of the geomorphic recession curves constructed from the DTM's of 67 US study basins. Finally, by use of the specific discharge u = Q/A, we link the two previous results and define the specific recession curves, whose collapse across basins within homogeneous geographical areas lends further, decisive, support to the notion that the statistical properties of observational recession curves bear the signature of the geomorphological structure of the networks producing them.
Extinction curves expected in young galaxies
Hiroyuki Hirashita; Takaya Nozawa; Takashi Kozasa; Takako T. Ishii; Tsutomu T. Takeuchi
2005-01-10
We investigate the extinction curves of young galaxies in which dust is supplied from Type II supernovae (SNe II) and/or pair instability supernovae (PISNe). We adopt Nozawa et al. (2003) for compositions and size distribution of grains formed in SNe II and PISNe. We find that the extinction curve is quite sensitive to internal metal mixing in supernovae (SNe). The extinction curves predicted from the mixed SNe are dominated by SiO2 and is characterised by steep rise from infrared to ultraviolet (UV). The dust from unmixed SNe shows shallower extinction curve, because of the contribution from large-sized (~ 0.1 um) Si grains. However, the progenitor mass is important in unmixed SNe II: If the progenitor mass is smaller than ~ 20 Msun, the extinction curve is flat in UV; otherwise, the extinction curve rises toward the short wavelength. The extinction curve observed in a high-redshift quasar (z=6.2) favours the dust production by unmixed SNe II. We also provide some useful observational quantities, so that our model might be compared with future high-z extinction curves.
Curve fitting How-to by W. Garrett Mitchener
Mitchener, W. Garrett
Curve fitting How-to by W. Garrett Mitchener This worksheet goes over traditional linear and non-linear least squares curve fitting and different ways to do it in Mathematica. It also goes over maximum likelihood curve fitting. Along the way, it shows different functions for finding maxima and minima
OP09O-OP404-9 Wide Field Camera 3 CCD Quantum Efficiency Hysteresis
NASA Technical Reports Server (NTRS)
Collins, Nick
2009-01-01
The HST/Wide Field Camera (WFC) 3 UV/visible channel CCD detectors have exhibited an unanticipated quantum efficiency hysteresis (QEH) behavior. At the nominal operating temperature of -83C, the QEH feature contrast was typically 0.1-0.2% or less. The behavior was replicated using flight spare detectors. A visible light flat-field (540nm) with a several times full-well signal level can pin the detectors at both optical (600nm) and near-UV (230nm) wavelengths, suppressing the QEH behavior. We are characterizing the timescale for the detectors to become unpinned and developing a protocol for flashing the WFC3 CCDs with the instrument's internal calibration system in flight. The HST/Wide Field Camera 3 UV/visible channel CCD detectors have exhibited an unanticipated quantum efficiency hysteresis (QEH) behavior. The first observed manifestation of QEH was the presence in a small percentage of flat-field images of a bowtie-shaped contrast that spanned the width of each chip. At the nominal operating temperature of -83C, the contrast observed for this feature was typically 0.1-0.2% or less, though at warmer temperatures contrasts up to 5% (at -50C) have been observed. The bowtie morphology was replicated using flight spare detectors in tests at the GSFC Detector Characterization Laboratory by power cycling the detector while cold. Continued investigation revealed that a clearly-related global QE suppression at the approximately 5% level can be produced by cooling the detector in the dark; subsequent flat-field exposures at a constant illumination show asymptotically increasing response. This QE "pinning" can be achieved with a single high signal flat-field or a series of lower signal flats; a visible light (500-580nm) flat-field with a signal level of several hundred thousand electrons per pixel is sufficient for QE pinning at both optical (600nm) and near-UV (230nm) wavelengths. We are characterizing the timescale for the detectors to become unpinned and developing a protocol for flashing the WFC3 CCDs with the instrument's internal calibration system in flight. A preliminary estimate of the decay timescale for one detector is that a drop of 0.1-0.2% occurs over a ten day period, indicating that relatively infrequent cal lamp exposures can mitigate the behavior to extremely low levels.
Jordan curves and funnel sections
NASA Astrophysics Data System (ADS)
Pugh, Charles; Wu, Conan
A continuous ordinary vector differential equation in Euclidean space has a funnel of solutions through each initial condition. Its cross-section at time t is a continuum. Many continua are known to be funnel sections: For instance the circle is a cross-section of a continuous ODE y'=f(t,y) where y is a variable in the plane, but it is not known whether every Jordan curve J is a planar funnel section. In this paper we give sufficient conditions that imply J is a planar funnel section - "pierceability." We show that pierceability is not generic when we put a fairly interesting complete metric on the space of Jordan curves. We also give proofs of several statements in the first author's paper on funnel sections that appeared in the JDE in 1975.
Living in Curved Momentum Space
J. Kowalski-Glikman
2013-09-10
In this paper we review some aspects of relativistic particles' mechanics in the case of a non-trivial geometry of momentum space. We start with showing how the curved momentum space arises in the theory of gravity in 2+1 dimensions coupled to particles, when (topological) degrees of freedom of gravity are solved for. We argue that there might exist a similar topological phase of quantum gravity in 3+1 dimensions. Then we characterize the main properties of the theory of interacting particles with curved momentum space and the symmetries of the action. We discuss the spacetime picture and the emergence of the principle of relative locality, according to which locality of events is not absolute but becomes observer dependent, in the controllable, relativistic way. We conclude with the detailed review of the most studied kappa-Poincare framework, which corresponds to the de Sitter momentum space.
Quantum walks in curved spacetime
Pablo Arrighi; Stefano Facchini; Marcelo Forets
2015-05-26
A discrete-time Quantum Walk (QW) is essentially a unitary operator driving the evolution of a single particle on the lattice. Some QWs admit a continuum limit, leading to familiar PDEs (e.g. the Dirac equation), and thus provide us with discrete toy models of familiar particles (e.g. the electron). In this paper, we study the continuum limit of a wide class of QWs, and show that it leads to all those PDEs corresponding to the Hamiltonian form of the massive curved Dirac equation in (1 + 1) dimensions. Therefore a certain QW, which we make explicit, provides us with a unitary discrete toy model of the electron as a test particle in curved spacetime, in spite of the fixed background lattice. Mathematically we have introduced two novel ingredients for taking the continuum limit of a QW, but which apply to any quantum cellular automata: encoding and grouping.
23. DETAIL OF TRELLIS BEAMS SHOWING RECESSED LIGHTING FIXTURES, WITH ...
23. DETAIL OF TRELLIS BEAMS SHOWING RECESSED LIGHTING FIXTURES, WITH ONE BEAM CURVED TO FIT AROUND TRUNK OF FORMER TREE. - Fallingwater, State Route 381 (Stewart Township), Ohiopyle, Fayette County, PA
10. VIEW SHOWING TWO BUTTRESSES ON THE NORTH ELEVATION, WHICH ...
10. VIEW SHOWING TWO BUTTRESSES ON THE NORTH ELEVATION, WHICH SUPPORT A DEEP CURVE IN THE LONGEST SECTION OF THE WALL, LOOKING SOUTH-SOUTHWEST - Rock Wall, North side of Battle Creek Canyon, Shingletown, Shasta County, CA
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.
Research and optimization on stator curve for roller pump
NASA Astrophysics Data System (ADS)
Yang, G. L.; Zhang, J. F.; Su, H. S.; Zhang, L. Q.
2013-12-01
By analyzing the advantages and disadvantages of common roller pump's stator curve (assuming that the roller on this stator curve has eliminated the void point), using curve fitting transitional method to pass the soft and hard impact point, then we can obtain a high order stator curve which has lower noise. By creating a smooth stator curve (and an inflection point with a common tangent) radial velocity mutation is eliminated. In order to avoid radial velocity mutation a symmetrical radial acceleration curve is used. In order to eliminate radial acceleration mutation, both ends of the radial acceleration change rate curve are valued zero. The results showed that due to the catastrophe point of the roller's stator curve, improving its stator curve eliminates the void point and the soft and hard impact point of the roller on the stator transitional curve. Compare the eighth-power stator curve with the improved stator curve, the improved curve also has the same superior performance. On the improved stator curve, the flow pulsation could be decreased by 241.39mL/min, with which the abrasion of the roller, the impact of the pump and the noise of the pump can be reduced.
Hysteresis conditions the vertical position of deep chlorophyll maximum in the temperate ocean
NASA Astrophysics Data System (ADS)
Navarro, Gabriel; Ruiz, Javier
2013-12-01
chlorophyll maxima (DCMs) are widespread features of oceans. In temperate regions, DCMs are commonly associated with isopycnal surfaces that frequently move over a wide vertical range. This general association between DCMs and isopycnals remains unexplained by present theories, and we show here that it emerges from the seasonal history of the water column. Analysis of the formation of more than 9000 seasonal DCMs throughout the world's oceans consistently locates the vertical position of spring/summer DCMs in temperate seas at the density of the previous winter mixed layer, independently of this density value and future depth. These results indicate that DCM formation cannot be understood without hysteresis by solely considering the instantaneous response of phytoplankton to vertical gradients in physical and chemical fields. Present theories for DCM formation cannot explain why spring and summer DCMs are systematically found at a density equal to that of the previous mixed layer where a bloom has occurred. Rather than reacting to instantaneous physical forcing, the results indicate that DCMs operate as self-preserving biological structures that are associated with particular isopycnals because of their capacity to modify the physicochemical environment. Combined with remote sensors to measure salinity and temperature in the surface ocean, this new understanding of DCM dynamics has the potential to improve the quantification of three-dimensional primary production via satellites. This significant enhancement of the representation of oceanic biological processes can also allow increasingly realistic predictions of future biogeochemical scenarios in a warming ocean.
Hysteresis-Based Mechanism for the Directed Motility of the Ncd Motor
Lakkaraju, Sirish Kaushik; Hwang, Wonmuk
2011-01-01
Ncd is a Kinesin-14 family protein that walks to the microtubule's minus end. Although available structures show its ?-helical neck in either pre- or post-stroke orientations, little is known about the transition between these two states. Using a combination of molecular dynamics simulations and structural analyses, we find that the neck sequentially makes intermediate contacts with the motor head along its mostly longitudinal path, and it develops a 24° twist in the post-stroke orientation. The forward (pre-stroke to post-stroke) motion has an ?4.5 kBT (where kB is the Boltzmann constant, and T = 300 K) free-energy barrier and is a diffusion guided by the intermediate contacts. The post-stroke free-energy minimum is higher and is formed ?10° before reaching the orientation in the post-stroke crystal structure, consistent with previous structural data. The importance of intermediate contacts correlates with the existing motility data, including those for mutant Ncds. Unlike the forward motion, the recovery stroke goes nearly downhill in free energy, powered in part by torsional relaxation of the neck. The hysteresis in the energetics of the neck motion arises from the mechanical compliance of the protein, and together with guided diffusion, it may be key to the directed motility of Ncd. PMID:21889447
NASA Astrophysics Data System (ADS)
Makhnovskiy, D. P.; Panina, L. V.; Mapps, D. J.
2001-06-01
This article concerns the investigation of the magnetic behavior of the surface impedance tensor final_sigmâ in CoSiB amorphous wires having a residual torsion stress and a helical anisotropy. The full tensor final_sigmâ involving three different components is found by measuring the S21 parameter at a required excitation with a Hewlett-Packard network/spectrum analyzer at MHz frequencies. In general, the impedance plots versus axial magnetic field Hex exhibit a hysteresis related to that for the case of static magnetization. The diagonal components of final_sigmâ (longitudinal final_sigmazz and circular final_sigma??) show a sharp peak in a narrow field interval where the domain walls form and contribute to the ac magnetization dynamics. This peak is not seen for the off-diagonal component final_sigmaz? (final_sigma?z) since the existence of the domain structure suppresses it. Applying a dc bias current results in a gradual transition to a nonhysteretic asymmetrical behavior with an enhanced sensitivity. The portions of the experimental plots associated with the rotational dynamic process are in qualitative agreement with the theory based on a single-domain model.
Makhnovskiy, D. P.; Panina, L. V.; Mapps, D. J.
2001-06-01
This article concerns the investigation of the magnetic behavior of the surface impedance tensor {cflx {var_sigma}} in CoSiB amorphous wires having a residual torsion stress and a helical anisotropy. The full tensor {cflx {var_sigma}} involving three different components is found by measuring the S{sub 21} parameter at a required excitation with a Hewlett-Packard network/spectrum analyzer at MHz frequencies. In general, the impedance plots versus axial magnetic field H{sub ex} exhibit a hysteresis related to that for the case of static magnetization. The diagonal components of {cflx {var_sigma}} (longitudinal {var_sigma}{sub zz} and circular {var_sigma}{sub {var_phi}{var_phi}}) show a sharp peak in a narrow field interval where the domain walls form and contribute to the ac magnetization dynamics. This peak is not seen for the off-diagonal component {var_sigma}{sub z{var_phi}} ({var_sigma}{sub {var_phi}z}) since the existence of the domain structure suppresses it. Applying a dc bias current results in a gradual transition to a nonhysteretic asymmetrical behavior with an enhanced sensitivity. The portions of the experimental plots associated with the rotational dynamic process are in qualitative agreement with the theory based on a single-domain model. {copyright} 2001 American Institute of Physics.
Cosmic string lensing and closed timelike curves
NASA Astrophysics Data System (ADS)
Shlaer, Benjamin; Tye, S.-H. Henry
2005-08-01
In an analysis of the gravitational lensing by two relativistic cosmic strings, we argue that the formation of closed timelike curves proposed by Gott is unstable in the presence of particles (e.g. the cosmic microwave background radiation). Because of the attractorlike behavior of the closed timelike curve, we argue that this instability is very generic. A single graviton or photon in the vicinity, no matter how soft, is sufficient to bend the strings and prevent the formation of closed timelike curves. We also show that the gravitational lensing due to a moving cosmic string is enhanced by its motion, not suppressed.
Replication and Analysis of Ebbinghaus’ Forgetting Curve
Murre, Jaap M. J.; Dros, Joeri
2015-01-01
We present a successful replication of Ebbinghaus’ classic forgetting curve from 1880 based on the method of savings. One subject spent 70 hours learning lists and relearning them after 20 min, 1 hour, 9 hours, 1 day, 2 days, or 31 days. The results are similar to Ebbinghaus' original data. We analyze the effects of serial position on forgetting and investigate what mathematical equations present a good fit to the Ebbinghaus forgetting curve and its replications. We conclude that the Ebbinghaus forgetting curve has indeed been replicated and that it is not completely smooth but most probably shows a jump upwards starting at the 24 hour data point. PMID:26148023
NASA Astrophysics Data System (ADS)
Beilsten-Edmands, J.; Eperon, G. E.; Johnson, R. D.; Snaith, H. J.; Radaelli, P. G.
2015-04-01
We present measurements of conductance hysteresis on CH3NH3PbI3 perovskite thin films, performed using the double-wave method, in order to investigate the possibility of a ferroelectric response. A strong frequency dependence of the hysteresis is observed in the range of 0.1 Hz to 150 Hz, with a hysteretic charge density in excess of 1000 ? C cm - 2 at frequencies below 0.4 Hz—a behaviour uncharacteristic of a ferroelectric response. We show that the observed hysteretic conductance, as well as the presence of a double arc in the impedance spectroscopy, can be fully explained by the migration of mobile ions under bias on a timescale of seconds. Our measurements place an upper limit of ? 1 ? C cm - 2 on any intrinsic frequency-independent polarisation, ruling out ferroelectricity as the main cause of current-voltage hysteresis and providing further evidence of the importance of ionic migration in modifying the efficiency of CH3NH3PbI3 devices.
NASA Astrophysics Data System (ADS)
Chen, Ting-Wei; Chang, Ken-Chia; Hsu, Che-Ju; Sheu, Chia-Rong; Wei, Ming-Dar
2013-09-01
Adjustable optical bistability and spatial hysteresis appearing in a Nd:GdVO4 laser with an intracavity liquid crystal (LC) cell were achieved. On the basis of optically induced LC reorientations and the varying magnitude of the order parameter, two types of LC were used to easily control the characteristics of hysteresis with a single control variable. Using an electrically driven twisted-nematic LC, an adjustable hysteresis area as well as a switching-on pump power was demonstrated and periodic spatiotemporal patterns were observed. By contrast, amplified hysteresis loops were obtained by increasing the rotation angle of homogeneous LC cells with a nearly invariable switching-on pump power.
The role of gouge and temperature on flash heating and its hysteresis
NASA Astrophysics Data System (ADS)
Platt, J. D.; Proctor, B.; Mitchell, T. M.; Hirth, G.; Goldsby, D. L.; Di Toro, G.; Beeler, N. M.; Tullis, T. E.
2014-12-01
Geophysical observations and high-velocity friction experiments suggest that mature faults weaken significantly during earthquakes. One proposed weakening mechanism is the breakdown of frictional contacts at a critical weakening temperature, a process known as flash heating. For bare surface sliding Rice [2006] showed that heat generation at frictional contacts triggers flash heating above a critical weakening velocity Vw of ~0.1 m/s. However, all faults generate a gouge layer at least a few millimeters wide, and the efficiency of flash heating in gouge is still unknown. Building on Beeler et al. [2008], we model flash heating in gouge by assuming that the total slip rate applied across the deforming zone is shared between multiple frictional contacts. Solving for the contact temperature we show that flash heating occurs when the strain rate exceeds a critical weakening strain rate controlled by the gouge properties. For a deforming zone 100 microns wide the equivalent Vw is ~4 m/s, making flash heating much less efficient in gouge than for bare surfaces. The lower contact slip rate associated with distributed shear leads to longer contact lifetimes, increasing the thickness of the thermal boundary layer at a slipping contact W. We show that W can become comparable to the expected spacing between slipping contacts D. Accounting for this in a new model for contact temperature we show that when W » D flash heating begins at much lower slip rates, and friction decreases slowly as the slip rate increases. Finally we study the hysteresis commonly seen in bare surface experiments, with higher friction observed during acceleration than deceleration. Accounting for the sensitive dependence of Vw on sliding surface temperature Tf allows us to match some experimental data for both acceleration and deceleration over a wide range of slip rates. Building on this we discuss how flash heating may operate near the trailing edge of a rupture where temperatures are high and slip is decelerating.
NASA Astrophysics Data System (ADS)
Vassiliou, Peter J.
2009-10-01
Cartan's method of moving frames is briefly recalled in the context of immersed curves in the homogeneous space of a Lie group G. The contact geometry of curves in low dimensional equi-affine geometry is then made explicit. This delivers the complete set of invariant data which solves the G-equivalence problem via a straightforward procedure, and which is, in some sense a supplement to the equivariant method of Fels and Olver. Next, the contact geometry of curves in general Riemannian manifolds (M,g) is described. For the special case in which the isometries of (M,g) act transitively, it is shown that the contact geometry provides an explicit algorithmic construction of the differential invariants for curves in M. The inputs required for the construction consist only of the metric g and a parametrisation of structure group SO(n); the group action is not required and no integration is involved. To illustrate the algorithm we explicitly construct complete sets of differential invariants for curves in the Poincaré half-space H3 and in a family of constant curvature 3-metrics. It is conjectured that similar results are possible in other Cartan geometries.
Titania nanorods curve to lower their energy
NASA Astrophysics Data System (ADS)
Zhang, Hengzhong; Finnegan, Michael P.; Banfield, Jillian F.
2013-07-01
Spontaneous formation of curved nanorods is generally unexpected, since curvature introduces strain energy. However, electron microscopy shows that under hydrothermal conditions, some nanorods grown by oriented attachment of small anatase particles on {101} surfaces are curved and dislocation free. Molecular dynamics simulations show that the lattice energy of a curved anatase rod is actually lower than that of a linear rod due to more attractive long-range interatomic Coulombic interactions among atoms in the curved rod. The thermodynamic driving force stemming from lattice energy could be harnessed to produce asymmetric morphologies unexpected from classical Ostwald ripening with unusual shapes and properties.Spontaneous formation of curved nanorods is generally unexpected, since curvature introduces strain energy. However, electron microscopy shows that under hydrothermal conditions, some nanorods grown by oriented attachment of small anatase particles on {101} surfaces are curved and dislocation free. Molecular dynamics simulations show that the lattice energy of a curved anatase rod is actually lower than that of a linear rod due to more attractive long-range interatomic Coulombic interactions among atoms in the curved rod. The thermodynamic driving force stemming from lattice energy could be harnessed to produce asymmetric morphologies unexpected from classical Ostwald ripening with unusual shapes and properties. Electronic supplementary information (ESI) available: Synthesis of nanocrystalline titania; X-ray characterization of samples; electron microscopy (TEM and SEM) examination of samples; surface charges needed to bend an anatase nanorod; structure modeling and energy minimization; molecular dynamics (MD) simulations; structures of anatase nanorods from MD. See DOI: 10.1039/c3nr02616g
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.
Unzipping DNA by a periodic force: Hysteresis loop area and its scaling
NASA Astrophysics Data System (ADS)
Kapri, Rajeev
2014-12-01
Using Monte Carlo simulations, we study the hysteresis in the unzipping of double-stranded DNA whose ends are subjected to a time-dependent periodic force with frequency (? ) and amplitude (G ). For the static force, i.e., ? ?0 , the DNA is in equilibrium with no hysteresis. On increasing ? , the area of the hysteresis loop initially increases and becomes maximum at frequency ?*(G ) , which depends on the force amplitude G . If the frequency is increased further, we find that for lower amplitudes the loop area decreases monotonically to zero, but for higher amplitudes it has an oscillatory component. The height of subsequent peaks decreases, and finally the loop area becomes zero at very high frequencies. The number of peaks depends on the length of the DNA. We give a simple analysis to estimate the frequencies at which maxima and minima occur in the loop area. We find that the area of the hysteresis loop scales as 1 /? in the high-frequency regime, whereas it scales as G??? with exponents ? =1 and ? =5 /4 at low frequencies. The values of the exponents ? and ? are different from the exponents reported earlier based on the hysteresis of small hairpins.
Model for understanding thermal hysteresis during heat stress: a matter of direction.
Parkhurst, A M
2010-11-01
Thermal hysteresis may be used to quantify and characterize the amount of heat stress an animal experiences. Heat stress studies of farm animals suggest that above a certain threshold body temperature (Tb) is driven by ambient temperature (Ta). Patterns in the Tb-Ta phase diagram indicate the presence of hysteresis. When hysteresis is present, there are two values for Tb depending on whether Ta is increasing or decreasing. A theoretical delay-relay model is proposed to illustrate the hysteretic dynamics of the Tb-Ta relationship when Ta is cyclic. Two types of hysteresis, transitional and thermal, are identified. Thermal hysteresis becomes prominent when Ta forces Tb into an elliptical limit cycle. The area of the ellipse is an indication of the animal's heat load. Also, the resulting Tb-Ta pattern depends on the delay (or lag) between Tb and Ta. The delay suggests possible levels of heat stress. A greater delay between Tb and Ta indicates more time is needed to dissipate the heat load, implying the animal is suffering more heat stress. For a given Ta, the Tb on the decreasing (recovery) path is always higher than the Tb on the increasing (challenge) path. Essentially, the animal requires more energy to dissipate heat than to absorb it. PMID:20140629
Conjugation of type I antifreeze protein to polyallylamine increases thermal hysteresis activity.
Can, Ozge; Holland, Nolan B
2011-10-19
Antifreeze proteins (AFPs) are ice binding proteins found in some plants, insects, and Antarctic fish allowing them to survive at subzero temperatures by inhibiting ice crystal growth. The interaction of AFPs with ice crystals results in a difference between the freezing and melting temperatures, termed thermal hysteresis, which is the most common measure of AFP activity. Creating antifreeze protein constructs that reduce the concentration of protein needed to observe thermal hysteresis activities would be beneficial for diverse applications including cold storage of cells or tissues, ice slurries used in refrigeration systems, and food storage. We demonstrate that conjugating multiple type I AFPs to a polyallylamine chain increases thermal hysteresis activity compared to the original protein. The reaction product is approximately twice as active when compared to the same concentration of free proteins, yielding 0.5 °C thermal hysteresis activity at 0.3 mM protein concentration. More impressively, the amount of protein required to achieve a thermal hysteresis of 0.3 °C is about 100 times lower when conjugated to the polymer (3 ?M) compared to free protein (300 ?M). Ice crystal morphologies observed in the presence of the reaction product are comparable to those of the protein used in the conjugation reaction. PMID:21905742
Optimal packing of curved filaments
NASA Astrophysics Data System (ADS)
Cajamarca, Luis; Grason, Gregory
2014-03-01
The interactions between straight filaments generically favor a uniform hexagonal arrangement, a packing motif that is frustrated when filaments are curved which forces a compromise between uniform spacing and uniform shape. Examples of curved biological filaments include bacterial flagella and filamentous components of the bacterial cytoskeleton. We address a simple question: what is the optimal ground state packing of N curved filaments? We present a geometric and mechanical model that incorporates the helical shape of the filaments and adhesive interactions, described by hard tube short-range repulsion and larger range of inter-filament attraction. We discuss two generic geometric classes of helical filament packings: vertically-stacked (N-plies) and side-to-side (N-packs). While N-plies maintain constant spacing with neighbors at constant shape, the cylindrical structure of the enclosing packing space limits the number and coordination of helices of a given geometry, resulting in fewer adhesive contacts than the ``looser'' N-pack class, where the lateral packing is unconstrained. We show that this geometric interplay gives rise to rich phase diagram of optimal packing, sensitively dependent to helical geometry, range of adhesion and filament number.
NSDL National Science Digital Library
Monroy, Harumi
2006-01-01
Calculus texts have problems on finding the Areas between Curves in the chapters on applications of Integration. The NCB suggests finding some of these examples in a text and trying them in Harumi's graph. Experimenting on a computer with the approximation for finding the area using rectangles is fascinating. As the number of rectangles increases, the approximation improves. Therefore, mathematicians define the area A between the two curves as the limit of the sum of the areas of these approximating rectangles where n is the number of rectangles bounded between a and b.
IGMtransmission: Transmission curve computation
NASA Astrophysics Data System (ADS)
Harrison, Christopher M.; Meiksin, Avery; Stock, David
2015-04-01
IGMtransmission is a Java graphical user interface that implements Monte Carlo simulations to compute the corrections to colors of high-redshift galaxies due to intergalactic attenuation based on current models of the Intergalactic Medium. The effects of absorption due to neutral hydrogen are considered, with particular attention to the stochastic effects of Lyman Limit Systems. Attenuation curves are produced, as well as colors for a wide range of filter responses and model galaxy spectra. Photometric filters are included for the Hubble Space Telescope, the Keck telescope, the Mt. Palomar 200-inch, the SUBARU telescope and UKIRT; alternative filter response curves and spectra may be readily uploaded.
Escudero, Carlos
2009-08-15
Stochastic growth phenomena on curved interfaces are studied by means of stochastic partial differential equations. These are derived as counterparts of linear planar equations on a curved geometry after a reparametrization invariance principle has been applied. We examine differences and similarities with the classical planar equations. Some characteristic features are the loss of correlation through time and a particular behavior of the average fluctuations. Dependence on the metric is also explored. The diffusive model that propagates correlations ballistically in the planar situation is particularly interesting, as this propagation becomes nonuniversal in the new regime.
Carlos Escudero
2009-06-28
Stochastic growth phenomena on curved interfaces are studied by means of stochastic partial differential equations. These are derived as counterparts of linear planar equations on a curved geometry after a reparametrization invariance principle has been applied. We examine differences and similarities with the classical planar equations. Some characteristic features are the loss of correlation through time and a particular behaviour of the average fluctuations. Dependence on the metric is also explored. The diffusive model that propagates correlations ballistically in the planar situation is particularly interesting, as this propagation becomes nonuniversal in the new regime.
Three-Body Choreographies in Given Curves
Hiroshi Ozaki; Hiroshi Fukuda; Toshiaki Fujiwara
2009-06-12
As shown by Johannes Kepler in 1609, in the two-body problem, the shape of the orbit, a given ellipse, and a given non-vanishing constant angular momentum determines the motion of the planet completely. Even in the three-body problem, in some cases, the shape of the orbit, conservation of the centre of mass and a constant of motion (the angular momentum or the total energy) determines the motion of the three bodies. We show, by a geometrical method, that choreographic motions, in which equal mass three bodies chase each other around a same curve, will be uniquely determined for the following two cases. (i) Convex curves that have point symmetry and non-vanishing angular momentum are given. (ii) Eight-shaped curves which are similar to the curve for the figure-eight solution and the energy constant are given. The reality of the motion should be tested whether the motion satisfies an equation of motion or not. Extensions of the method for generic curves are shown. The extended methods are applicable to generic curves which does not have point symmetry. Each body may have its own curve and its own non-vanishing masses.
Generating artificial light curves: revisited and updated
NASA Astrophysics Data System (ADS)
Emmanoulopoulos, D.; McHardy, I. M.; Papadakis, I. E.
2013-08-01
The production of artificial light curves with known statistical and variability properties is of great importance in astrophysics. Consolidating the confidence levels during cross-correlation studies, understanding the artefacts induced by sampling irregularities, establishing detection limits for future observatories are just some of the applications of simulated data sets. Currently, the widely used methodology of amplitude and phase randomization is able to produce artificial light curves which have a given underlying power spectral density (PSD) but which are strictly Gaussian distributed. This restriction is a significant limitation, since the majority of the light curves, e.g. active galactic nuclei, X-ray binaries, gamma-ray bursts, show strong deviations from Gaussianity exhibiting `burst-like' events in their light curves yielding long-tailed probability density functions (PDFs). In this study, we propose a simple method which is able to precisely reproduce light curves which match both the PSD and the PDF of either an observed light curve or a theoretical model. The PDF can be representative of either the parent distribution or the actual distribution of the observed data, depending on the study to be conducted for a given source. The final artificial light curves contain all of the statistical and variability properties of the observed source or theoretical model, i.e. the same PDF and PSD, respectively. Within the framework of Reproducible Research, the code and the illustrative example used in this paper are both made publicly available in the form of an interactive MATHEMATICA notebook.
Elliptic Curves David Wright Escott
Stein, William
curves while* * defined as algebraic curves in projective space, have a natural group structure which every elliptic curve over Fp has a rational point. The Proof of this theorem requires* * a great deal to take this as * *a curve in projective space: Y 2Z + aXY Z + bY Z2 = X3 + cX2Z + d
Shen, Yizhou; Tao, Jie; Tao, Haijun; Chen, Shanlong; Pan, Lei; Wang, Tao
2015-09-23
The contact time of impacting water droplets on superhydrophobic surfaces directly reflects the extent of thermal and energy conversions between the water droplet and the surface, which is also considered to be crucial to the practical applications. The purpose of this study was to reveal the relationship between the contact time and the wetting hysteresis. We designed and fabricated six classes of surfaces with different extent of hydrophobicity through modifying the microscale/nanoscale hierarchical textured titanium surfaces with 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, and we filmed the contact process of the water droplet impacting on these surfaces using a high-speed camera. It can be concluded that wetting hysteresis played a significant role in determining how long the impacting water droplet can bounce off the surface, based on the interfacial wetting mechanism and the work done against the resistance force generated by contact angle hysteresis during the dynamic process. PMID:26331793
Technical Note: Testing an improved index for analysing storm nutrient hysteresis
NASA Astrophysics Data System (ADS)
Lloyd, C. E. M.; Freer, J. E.; Johnes, P. J.; Collins, A. L.
2015-08-01
Analysis of hydrochemical behaviour in extreme flow events can provide new insights into the process controls on nutrient transport in catchments. The examination of storm behaviours using hysteresis analysis has increased in recent years, partly due to the increased availability of high temporal resolution datasets for discharge and nutrient parameters. A number of these analyses involve the use of an index to describe the characteristics of a hysteresis loop in order to compare different storm behaviours both within and between catchments. This technical note reviews the methods for calculation of the hysteresis index (HI) and explores a new more effective methodology. Each method is systematically tested and the impact of the chosen calculation on the results is examined. Recommendations are made regarding the most effective method of calculating a HI which can be used for comparing data between storms and between different parameters and catchments.
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.
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.
NASA Astrophysics Data System (ADS)
Gallé, G.; Etrillard, C.; Degert, J.; Guillaume, F.; Létard, J.-F.; Freysz, E.
2013-02-01
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)2 trz](BF4)2-H2O 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 ?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.
Diminution of contact angle hysteresis under the influence of an oscillating force.
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
Galle, G.; Degert, J.; Freysz, E.; Etrillard, C.; Letard, J.-F.; Guillaume, F.
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.
A Ni-Cd battery model considering state of charge and hysteresis effects
NASA Astrophysics Data System (ADS)
García-Plaza, M.; Serrano-Jiménez, D.; Eloy-García Carrasco, J.; Alonso-Martínez, J.
2015-02-01
This paper introduces an electrical battery model. Based on a Thévenin circuit with two RC parallel branches, it includes an ampère-hour counting method to estimate the state of charge (SOC) and a novel model for the hysteresis. The presented model can consider variations in its parameters under changes in all of its internal and external variables, although only SOC and hysteresis are considered. Hysteresis consideration does not only allow distinguishing the parameters during charging and discharging, but also during transients between them. The model was designed to be capable of being implemented in online and offline systems. Finally the proposed model was validated for a single Ni-Cd cell, characterized by current interruption method, in an offline system. The validation was also extended to a stack of 210 cells of the same technology.
NASA Astrophysics Data System (ADS)
Tunnell, Andrew; Ballarotto, Vincent; Cumings, John
2014-01-01
We present a measurement protocol that effectively eliminates both the hysteresis and the temporal drift typically observed in the channel conductance of single-walled carbon nanotube field-effect transistors (SWNT FETs) during the application of gate voltages. Before each resistance measurement, the gate is first stepped through a series of alternating positive and negative voltages to produce a neutral charge distribution within the device. This process is highly effective at removing the hysteresis in the channel conductance, and time-dependent measurements further demonstrate that the drain current is stable and single-valued, independent of the prior measurement history. The effectiveness of this method can be understood within the Preisach hysteresis model, which we demonstrate as a useful framework to predict the observed results.
Regularity of curve integrable spacetimes
Yafet Sanchez Sanchez
2015-06-16
The idea of defining a gravitational singularity as an obstruction to the dynamical evolution of a test field (described by a PDE) rather than the dynamical evolution of a particle (described by a geodesics) is explored. In particular, the concept of field regularity is introduced which serves to describe the well-posedness of the local initial value problem for a given field.In particular this is applied to (classical) scalar fields in the class of curve integrable spacetimes to show that the classical singularities do not interrupt the well-posedness of the wave equation.
ERIC Educational Resources Information Center
Harper, Suzanne R.; Driskell, Shannon
2005-01-01
Graphic tips for using the Geometer's Sketchpad (GSP) are described. The methods to import an image into GSP, define a coordinate system, plot points and curve fit the function using a graphical calculator are demonstrated where the graphic features of GSP allow teachers to expand the use of the technology application beyond the classroom.
Uncertainty propagation: Curve fitting
NSDL National Science Digital Library
2013-06-21
Students will learn a sample-variance curve fitting method that can be used to determine whether a set of experimental data appears to have been generated by a model. This method is based on minimizing the reduced chi-squared value. This video includes a reminder to inspect normalized residuals before reporting fitted parameters.
ERIC Educational Resources Information Center
Hunter, Walter M.
This document contains detailed directions for constructing a device that mechanically produces the three-dimensional shape resulting from the rotation of any algebraic line or curve around either axis on the coordinate plant. The device was developed in response to student difficulty in visualizing, and thus grasping the mathematical principles…
ERIC Educational Resources Information Center
Meredith, William; Tisak, John
1990-01-01
A model based on latent trait theory, with maximum likelihood parameter estimates and associated asymptotic tests, is presented. Latent curve analysis is a method for representing development and is an alternative to repeated measures analysis of variance and first-order auto-regressive models. (SLD)
Strong, Lighweight Curved Panels
NASA Technical Reports Server (NTRS)
Molho, R.; Bestor, H. L.
1985-01-01
Sandwich construction gives panels structural efficiency. Large panels with compound curvatures are formed from a honeycomb core faced with sheets of graphite/epoxy cloth and tape. Developed for pod on Space Shuttle, construction readily adapted to curved skin panels on cars, trucks, and airplanes.
ERIC Educational Resources Information Center
Paulton, Richard J. L.
1991-01-01
A procedure that allows students to view an entire bacterial growth curve during a two- to three-hour student laboratory period is described. Observations of the lag phase, logarithmic phase, maximum stationary phase, and phase of decline are possible. A nonpathogenic, marine bacterium is used in the investigation. (KR)
B. Czerny
2006-12-16
The presence of the dust in the circumnuclear region strongly affects our view of the nucleus itself. The effect is strong in type 2 objects but weaker effect is likely to be present in type 1 objects as well. In these objects a correction to the observed optical/UV spectrum must be done in order to recover the intrinsic spectrum of a nucleus. The approach based on the extinction curve is convenient for that purpose so significant effort has been recently done in order to determine the extinction curve for the circumnuclear material. It seems clear that the circumnuclear dust is different from the average properties of the dust in the Interstellar Medium in our galaxy: the well known 2175 A feature is weak or absent in AGN nuclear dust, and the extinction curve at shorter wavelength does not seem to be rising as steeply. The circumnuclear dust is therefore more similar to SMC dust, or more likely, to the dust in very dense molecular clouds in our Galaxy. However, the exact shape of the extinction curve in the far UV is still a matter of debate, and various effects are difficult to disentangle.
ERIC Educational Resources Information Center
Bausell, R. Barker
1995-01-01
This editorial provides an informal review of "The Bell Curve" (Herrnstein and Murray, 1994). The book, packaged as scientific writing, is an attack on affirmative action and on government attempts to foster egalitarianism. It is a political treatise that assumes that racial differences in intelligence are valid and genetic. (SLD)
Curved nanostructured materials
Humberto Terrones; Mauricio Terrones
2003-01-01
Graphite is a layered material that is very flexible, in which each layer is able to curve in order to form cages, nanotubes, nanocoils, nanocones, etc. In this paper, we demonstrate that various synthetic routes are capable of producing graphite-like nanomaterials with fascinating electronic and mechanical properties. There are other layered systems, which could curl and bend, thus generating novel
Origin of anomalous hysteresis loops induced by femtosecond laser pulses in GdFeCo amorphous films
NASA Astrophysics Data System (ADS)
Xu, Chudong; Chen, Zhifeng; Chen, Daxin; Zhou, Shiming; Lai, Tianshu
2010-03-01
A controllable pump-pulse-number magneto-optical Kerr technique combined with an initializing field scanning approach is developed to eliminate and identify memory and accumulation effects, respectively, from external field history and multiple pulse excitations. A series of anomalous loops of GdFeCo films are measured for different amount of pump pulses using this technique, revealing that serious memory and accumulation effects exist in continuous-pulse-pumped anomalous hysteresis loops which show illusory information of hot coercivity and degree of magnetization reversal. Single-pulse-induced anomalous loop reveals that the hot coercivity shown by continuous-pulse-pumped anomalous loops is not the minimum external field that drives real magneto-optical recording.
NASA Astrophysics Data System (ADS)
Escobar, Juan V.; Garza, Cristina; Alonso, Juan Carlos; Castillo, Rolando
2013-05-01
Increased roughness is known to enhance the natural wetting properties of surfaces, making them either more hydrophobic or more hydrophilic. In this work we study the wetting properties of water and mercury drops in contact with boron doped diamond films with progressively increased surface roughnesses. We show how thermal oxidation of a microcrystalline film creates pyramids decorated with sub-micron protrusions that turn its naturally mercuryphobic surface into super-mercuryphobic. With this liquid, we observe the vanishment of the contact angle hysteresis that is expected for rough surfaces as the contact angle approaches 180?, making small drops of mercury roll along out of the surface at an apparent zero tilt-angle. In contrast, the incorporation of nano-globules on the oxidized surface through a silanization process is necessary to increase the hydrophobic properties of the film for which the contact angle with water reaches 138°. The wetting states that dominate in each case are discussed.
NASA Astrophysics Data System (ADS)
Shur, V. Ya.; Baturin, I. S.; Mingaliev, E. A.; Zorikhin, D. V.; Udalov, A. R.; Greshnyakov, E. D.
2015-02-01
The current paper presents a piezoelectric bimorph actuator produced by direct bonding of lithium niobate wafers with the mirrored Y and Z axes. Direct bonding technology allowed to fabricate bidomain plate with precise positioning of ideally flat domain boundary. By optimizing the cutting angle (128° Y-cut), the piezoelectric constant became as large as 27.3 pC/N. Investigation of voltage dependence of bending displacement confirmed that bimorph actuator has excellent linearity and hysteresis-free. Decrease of the applied voltage down to mV range showed the perfect linearity up to the sub-nm deflection amplitude. The frequency and temperature dependences of electromechanical transmission coefficient in wide temperature range (from 300 to 900 K) were investigated.
Magnetization plateaus and frequency dispersion of hysteresis on frustrated dipolar array
NASA Astrophysics Data System (ADS)
Zhang, You-Tian
2015-08-01
Competings or frustrated interactions are common for condensed matter systems. In consideration of the effect of dipole–dipole interaction, the static properties of square lattice spin systems are investigated using the Wang–Landau algorithm. The dynamic hysteresis is also simulated using the Monte Carlo (MC) method. The step-like magnetization under a DC magnetic field and two distinct peaks in hysteresis dispersion under an AC magnetic field are observed. Then, the formation of the properties of the frustrated dipolar array are discussed.
Li, Wei; Chen, Xuedong; Li, Zilong
2013-11-01
This paper presents a modified Bouc-Wen model for asymmetric rate-dependent hysteresis in piezoelectric actuator. On this basis, we develop a new digital inverse controller with a simple structure cascaded in the feedforward path for piezoelectric actuator. In order to eliminate modeling errors and parameter uncertainties, the developed inverse controller is combined with a feedback loop to establish a hybrid control scheme. In our experiments, the proposed model together with the developed hybrid control scheme has shown significantly reduced tracking errors caused by asymmetric rate-dependent hysteresis in piezoelectric actuator. PMID:24289430
de Ruiter, Riëlle; Semprebon, Ciro; van Gorcum, Mathijs; Duits, Michèl H G; Brinkmann, Martin; Mugele, Frieder
2015-06-12
The equilibrium shape of a drop in contact with solid surfaces can undergo continuous or discontinuous transitions upon changes in either drop volume or surface energies. In many instances, such transitions involve the motion of the three-phase contact line and are thus sensitive to contact angle hysteresis. Using a combination of electrowetting-based experiments and numerical calculations, we demonstrate for a generic sphere-plate confinement geometry how contact angle hysteresis affects the mechanical stability of competing axisymmetric and nonaxisymmetric drop conformations and qualitatively changes the character of transitions between them. PMID:26196804
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.
Contact angles and their hysteresis as a measure of liquid-solid adhesion.
Extrand, C W
2004-05-11
The wetting behavior of a series of aliphatic polyamides was examined. Polyamides and polyethylene were molded against glass to produce smooth surfaces. After cleaning, chemical composition of the surfaces was verified with X-ray photoelectron spectroscopy. Advancing and receding contact angles were measured from small sessile water drops. Contact angles decreased with amide content while contact angle hysteresis increased. Wetting free energies calculated from contact angles were equal to those from dewetting, suggesting that contact angle hysteresis did not arise from surface anomalies, but from hydrogen bonding between water and the amide groups in the polyamide surfaces. PMID:15969393
NASA Astrophysics Data System (ADS)
Yamada, Hisato; Watanabe, Kakeru; Ikushima, Kenji
2015-08-01
Magnetic hysteresis loops are measured by ultrasonic techniques and used in visualizing the magnetic-flux distribution in a steel plate. The piezomagnetic coefficient determines the amplitude of acoustically stimulated electromagnetic (ASEM) fields, yielding the hysteresis behavior of the intensity of the ASEM response. By utilizing the high correspondence of the ASEM response to the magnetic-flux density, we image the specific spatial patterns of the flux density formed by an artificial defect in a steel plate specimen. Magnetic-flux probing by ultrasonic waves is thus shown to be a viable method of nondestructive material inspection.
New Binary Systems With Asymmetric Light Curves
NASA Astrophysics Data System (ADS)
Virnina, Natalia A.
2010-12-01
We present the results of investigation of the light curves of 27 newly discovered binary systems. Among the examined curves, there were 10 curves with statistically significant asymmetry of maximums, according the 3? criterion for the difference between the maximal brightness. Half of these 10 curves have a higher first maximum, another half the second one. Two of these 10 curves, USNO-B1.0 1629-0064825 = VSX J052807.9+725606 and USNO-B1.0 1586-0116785, show the largest difference between magnitudes in maxima. The star VSX J052807.9+725606 also shows the secondary minimum, which is shifted from the phase ? = 0.5. The shape of the curve argues that the physical processes of this star could be close to that of well known short periodic binary system V361 Lyr, which has a spot on the surface of one star of the system. Another star, USNO-B1.0 1586-0116785, probably has a cold spot, or several spots, in the photosphere of one of the components.
Punishment in public goods games leads to meta-stable phase transitions and hysteresis.
Hintze, Arend; Adami, Christoph
2015-07-01
The evolution of cooperation has been a perennial problem in evolutionary biology because cooperation can be undermined by selfish cheaters who gain an advantage in the short run, while compromising the long-term viability of the population. Evolutionary game theory has shown that under certain conditions, cooperation nonetheless evolves stably, for example if players have the opportunity to punish cheaters that benefit from a public good yet refuse to pay into the common pool. However, punishment has remained enigmatic because it is costly and difficult to maintain. On the other hand, cooperation emerges naturally in the public goods game if the synergy of the public good (the factor multiplying the public good investment) is sufficiently high. In terms of this synergy parameter, the transition from defection to cooperation can be viewed as a phase transition with the synergy as the critical parameter. We show here that punishment reduces the critical value at which cooperation occurs, but also creates the possibility of meta-stable phase transitions, where populations can 'tunnel' into the cooperating phase below the critical value. At the same time, cooperating populations are unstable even above the critical value, because a group of defectors that are large enough can 'nucleate' such a transition. We study the mean-field theoretical predictions via agent-based simulations of finite populations using an evolutionary approach where the decisions to cooperate or to punish are encoded genetically in terms of evolvable probabilities. We recover the theoretical predictions and demonstrate that the population shows hysteresis, as expected in systems that exhibit super-heating and super-cooling. We conclude that punishment can stabilize populations of cooperators below the critical point, but it is a two-edged sword: it can also stabilize defectors above the critical point. PMID:26031571
Di Matteo, Tiziana
2223-01-01
Hysteresis losses in BSCCO(2223)/Ag multifilamentary tapes D. Zola *, M. Polichetti, C. Senatore, T. Allende, I-84081 Baronissi (Salerno), Italy Abstract In order to investigate hysteresis losses on Ag dependence of the hysteretic losses. In order to consider the role of the thermally activated flux creep
Hollington, James; Hillman, Susan J; Torres-Sánchez, Carmen; Boeckx, Jens; Crossan, Neil
2014-04-01
Load deflection and hysteresis measurements were made on 37 wheelchair seating cushions according to ISO 16840-2:2007. Load deflection plots for all 37 cushions are reported and fundamental aspects of graph interpretation discussed. ISO hysteresis data are also reported and interpretation discussed. PMID:24230981
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,...
Wu, Shin-Tson
--Hysteresis effects of two blue-phase (BP) liquid crys- tals BP-I and BP-II, and polymer-stabilized BP-I and BP-II are investigated. BP-I exhibits a relatively slow response time and a large hysteresis. After polymer stabilization, its operating voltage is increased slightly, but its response time is dramatically reduced
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
Steps in the hysteresis loops of a high-spin molecule Jonathan R. Friedman and M. P. Sarachik
Friedman, Jonathan R.
Steps in the hysteresis loops of a high-spin molecule Jonathan R. Friedman and M. P. Sarachik Corporation, Webster, New York 14580 We report the first observation of steps in the hysteresis loop of a high-spin molecular magnet. We propose that the steps, which occur every 0.46 T, are due to thermally assisted
Chaudhury, Manoj K.
to rationalize the adhesion hysteresis in AFM measurements, the anelastic deformationlo of the monolayer films5122 J. Phys. Chem. 1993, 97, 5122-5126 Correlation between Adhesion Hysteresis and Phase State of Monolayer Films Manoj K. Chaudhury' and Michael J. Owen Dow Corning Corporation, Midland, Michigan 48686
Learning Curves in Health Professions Education.
Pusic, Martin V; Boutis, Kathy; Hatala, Rose; Cook, David A
2015-08-01
Learning curves, which graphically show the relationship between learning effort and achievement, are common in published education research but are not often used in day-to-day educational activities. The purpose of this article is to describe the generation and analysis of learning curves and their applicability to health professions education. The authors argue that the time is right for a closer look at using learning curves-given their desirable properties-to inform both self-directed instruction by individuals and education management by instructors.A typical learning curve is made up of a measure of learning (y-axis), a measure of effort (x-axis), and a mathematical linking function. At the individual level, learning curves make manifest a single person's progress towards competence including his/her rate of learning, the inflection point where learning becomes more effortful, and the remaining distance to mastery attainment. At the group level, overlaid learning curves show the full variation of a group of learners' paths through a given learning domain. Specifically, they make overt the difference between time-based and competency-based approaches to instruction. Additionally, instructors can use learning curve information to more accurately target educational resources to those who most require them.The learning curve approach requires a fine-grained collection of data that will not be possible in all educational settings; however, the increased use of an assessment paradigm that explicitly includes effort and its link to individual achievement could result in increased learner engagement and more effective instructional design. PMID:25806621
Calabrese, G; Capineri, L; Granato, M; Frattini, G
2015-04-01
This paper describes the design of a system for the characterization of magnetic hysteresis behavior in soft ferrite magnetic cores. The proposed setup can test magnetic materials exciting them with controlled arbitrary magnetic field waveforms, including the capability of providing a DC bias, in a frequency bandwidth up to 500 kHz, with voltages up to 32 V peak-to-peak, and currents up to 10 A peak-to-peak. In order to have an accurate control of the magnetic field waveform, the system is based on a voltage controlled current source. The electronic design is described focusing on closed loop feedback stabilization and passive components choice. The system has real-time hysteretic loop acquisition and visualization. The comparisons between measured hysteresis loops of sample magnetic materials and datasheet available ones are shown. Results showing frequency and thermal behavior of the hysteresis of a test sample prove the system capabilities. Moreover, the B-H loops obtained with a multiple waveforms excitation signal, including DC bias, are reported. The proposal is a low-cost and replicable solution for hysteresis characterization of magnetic materials used in power electronics. PMID:25933882
NASA Astrophysics Data System (ADS)
Calabrese, G.; Capineri, L.; Granato, M.; Frattini, G.
2015-04-01
This paper describes the design of a system for the characterization of magnetic hysteresis behavior in soft ferrite magnetic cores. The proposed setup can test magnetic materials exciting them with controlled arbitrary magnetic field waveforms, including the capability of providing a DC bias, in a frequency bandwidth up to 500 kHz, with voltages up to 32 V peak-to-peak, and currents up to 10 A peak-to-peak. In order to have an accurate control of the magnetic field waveform, the system is based on a voltage controlled current source. The electronic design is described focusing on closed loop feedback stabilization and passive components choice. The system has real-time hysteretic loop acquisition and visualization. The comparisons between measured hysteresis loops of sample magnetic materials and datasheet available ones are shown. Results showing frequency and thermal behavior of the hysteresis of a test sample prove the system capabilities. Moreover, the B-H loops obtained with a multiple waveforms excitation signal, including DC bias, are reported. The proposal is a low-cost and replicable solution for hysteresis characterization of magnetic materials used in power electronics.
NASA Astrophysics Data System (ADS)
Hamilton, Reginald F.
Shape Memory Alloys (SMAs) undergo a reversible martensitic transformation (MT) that may be thermal- or stress-induced enabling the recovery of large deformations, up to 12% strain, can be fully recovered, albeit a hysteresis exists. Characterizing the hysteresis for classes of SMAs is essential for their practical application. It is well known that the hysteresis is due to energy dissipative mechanisms, with the primary mechanisms being frictional resistance to interfacial motion and partial plastic accommodation of shape and volume changes. In previous work, however, the origins of potential dissipative mechanisms have not been clarified, and the factors that influence these mechanisms (i.e. external stress fields, matrix strength properties, precipitate microstructure, plastic accommodation, detwinning, etc.) have not been investigated with rigorous experimentation. In this study, an experimental program is designed to address this issue. This comprehensive experimental program, including stress-free thermal cycling, constant load thermal cycling, and constant temperature stress/strain cycling, is undertaken for NiTi, CoNiAl, NiFeGa, and NiMnGa SMAs in the aged and unaged states. The NiFeGa and NiMnGa classes of SMAs undergo martensite to martensite inter-martensitic transformations. The experimental findings characterize the effect of second-phase particles and inter-martensitic transformations on the level of hysteresis. To ascertain physical mechanisms responsible for the hysteresis, in-situ transmission electron microscopy (TEM) analysis provides insight into microstructure features. The results expose the role of frictional resistance and partial plastic accommodation on the observed differential magnitudes of thermal and stress hysteresis. In particular, larger hysteresis magnitudes are mainly attributed to dislocation emissions at the austenite/martensite phase boundary, designated micro-scale plasticity, that lower coherent interface strains, and thus, relax the stored elastic strain energy. Remarkably, the effect of relaxation of coherent interface strains can be seen without significant levels of remnant macro-scale strain. Influences of energy dissipative mechanisms are rationalized using a theoretical approach which combines micro-mechanics and thermodynamics into a thermo-mechanical framework. Models are formulated for the thermal and stress hysteresis based on a thermo-mechanical framework so as to shed light into differential hysteresis magnitudes. Current theoretical formulations consider energy dissipation from a phenomenological point view and satisfy the second law of thermodynamics by considering a dissipative potential. In the current study, an earlier thermo-mechanical formulation is advanced beyond phenomenological considerations to include the effects of micro-scale plasticity. With this, the hysteresis models can account for energy dissipation resulting from strain energy relaxation. The current modeling approach provides intuitive predictions of the experimentally observed behavior particularly a growing hysteresis with increasing stress for NiTi alloys.
NASA Astrophysics Data System (ADS)
Zhang, Wen-jin; Peng, Yu-feng; Liu, Zhong-li
2014-05-01
We performed molecular dynamics (MD) simulations with the two embedded atom method (EAM) potentials to calculate the melting curves of cobalt over a wide range of pressure. Zhou's EAM potential can produce satisfying results, in better agreement with the experiment compared with Pun's. Based on Zhou's potential, we simulated the melting of Co with two approaches, i.e., the one-phase (hysteresis) method and two-phase (solid-liquid coexistence) method. Both approaches can effectively reduce the superheating, and their results are in the close proximity at the applied pressures. With the one-phase method, during the investigation of the entropy of fusion of Co, we found that with the pressure increasing, the entropy of fusion decreases rapidly first and then oscillates with pressure; when the pressure is beyond 100 GPa, the entropy of fusion shows less pressure effect. When taking account of the solid-liquid interfacial energy at different pressures, we found that it increases monotonically with pressure, and can be well described as a fifth-order polynomial relation. Moreover, the thermal equation of state (EOS) and the temperature dependence of atomic structures of Co have been obtained successfully.
Diffusion in Curved Spacetimes
Matteo Smerlak
2011-11-18
Using simple kinematical arguments, we derive the Fokker-Planck equation for diffusion processes in curved spacetimes. In the case of Brownian motion, it coincides with Eckart's relativistic heat equation (albeit in a simpler form), and therefore provides a microscopic justification for his phenomenological heat-flux ansatz. Furthermore, we obtain the small-time asymptotic expansion of the mean square displacement of Brownian motion in static spacetimes. Beyond general relativity itself, this result has potential applications in analogue gravitational systems.
Anatomical curve identification
Bowman, Adrian W.; Katina, Stanislav; Smith, Joanna; Brown, Denise
2015-01-01
Methods for capturing images in three dimensions are now widely available, with stereo-photogrammetry and laser scanning being two common approaches. In anatomical studies, a number of landmarks are usually identified manually from each of these images and these form the basis of subsequent statistical analysis. However, landmarks express only a very small proportion of the information available from the images. Anatomically defined curves have the advantage of providing a much richer expression of shape. This is explored in the context of identifying the boundary of breasts from an image of the female torso and the boundary of the lips from a facial image. The curves of interest are characterised by ridges or valleys. Key issues in estimation are the ability to navigate across the anatomical surface in three-dimensions, the ability to recognise the relevant boundary and the need to assess the evidence for the presence of the surface feature of interest. The first issue is addressed by the use of principal curves, as an extension of principal components, the second by suitable assessment of curvature and the third by change-point detection. P-spline smoothing is used as an integral part of the methods but adaptations are made to the specific anatomical features of interest. After estimation of the boundary curves, the intermediate surfaces of the anatomical feature of interest can be characterised by surface interpolation. This allows shape variation to be explored using standard methods such as principal components. These tools are applied to a collection of images of women where one breast has been reconstructed after mastectomy and where interest lies in shape differences between the reconstructed and unreconstructed breasts. They are also applied to a collection of lip images where possible differences in shape between males and females are of interest. PMID:26041943
Schulz, Douglas A.
2007-10-08
A biometric system suitable for validating user identity using only mouse movements and no specialized equipment is presented. Mouse curves (mouse movements with little or no pause between them) are individually classied and used to develop classication histograms, which are representative of an individual's typical mouse use. These classication histograms can then be compared to validate identity. This classication approach is suitable for providing continuous identity validation during an entire user session.
Francesco Caravelli
2012-03-02
Quantum Graphity is an approach to quantum gravity based on a background independent formulation of condensed matter systems on graphs. We summarize recent results obtained on the notion of emergent geometry from the point of view of a particle hopping on the graph. We discuss the role of connectivity in emergent Lorentzian perturbations in a curved background and the Bose--Hubbard (BH) model defined on graphs with particular symmetries.
NASA Astrophysics Data System (ADS)
Frønsdal, Christian; Kontsevich, Maxim
2007-02-01
Deformation quantization on varieties with singularities offers perspectives that are not found on manifolds. The Harrison component of Hochschild cohomology, vanishing on smooth manifolds, reflects information about singularities. The Harrison 2-cochains are symmetric and are interpreted in terms of abelian *-products. This paper begins a study of abelian quantization on plane curves over mathbb{C}, being algebraic varieties of the form {mathbb{C}}^2/R, where R is a polynomial in two variables; that is, abelian deformations of the coordinate algebra mathbb{C}[x,y]/(R). To understand the connection between the singularities of a variety and cohomology we determine the algebraic Hochschild (co)homology and its Barr Gerstenhaber Schack decomposition. Homology is the same for all plane curves mathbb{C}[x,y]/R, but the cohomology depends on the local algebra of the singularity of R at the origin. The Appendix, by Maxim Kontsevich, explains in modern mathematical language a way to calculate Hochschild and Harrison cohomology groups for algebras of functions on singular planar curves etc. based on Koszul resolutions.
Learning curves in classification with microarray data.
Hess, Kenneth R; Wei, Caimiao
2010-02-01
The performance of many repeated tasks improves with experience and practice. This improvement tends to be rapid initially and then decreases. The term "learning curve" is often used to describe the phenomenon. In supervised machine learning, the performance of classification algorithms often increases with the number of observations used to train the algorithm. We use progressively larger samples of observations to train the algorithm and then plot performance against the number of training observations. This yields the familiar negatively accelerating learning curve. To quantify the learning curve, we fit inverse power law models to the progressively sampled data. We fit such learning curves to four large clinical cancer genomic datasets, using three classifiers (diagonal linear discriminant analysis, K-nearest-neighbor with three neighbors, and support vector machines) and four values for the number of top genes included (5, 50, 500, 5,000). The inverse power law models fit the progressively sampled data reasonably well and showed considerable diversity when multiple classifiers are applied to the same data. Some classifiers showed rapid and continued increase in performance as the number of training samples increased, while others showed little if any improvement. Assessing classifier efficiency is particularly important in genomic studies since samples are so expensive to obtain. It is important to employ an algorithm that uses the predictive information efficiently, but with a modest number of training samples (>50), learning curves can be used to assess the predictive efficiency of classification algorithms. PMID:20172367
Hysteresis, phase transitions, and dangerous transients in electrical power distribution systems.
Duclut, Charlie; Backhaus, Scott; Chertkov, Michael
2013-06-01
The majority of dynamical studies in power systems focus on the high-voltage transmission grids where models consider large generators interacting with crude aggregations of individual small loads. However, new phenomena have been observed indicating that the spatial distribution of collective, nonlinear contribution of these small loads in the low-voltage distribution grid is crucial to the outcome of these dynamical transients. To elucidate the phenomenon, we study the dynamics of voltage and power flows in a spatially extended distribution feeder (circuit) connecting many asynchronous induction motors and discover that this relatively simple 1+1 (space+time) dimensional system exhibits a plethora of nontrivial spatiotemporal effects, some of which may be dangerous for power system stability. Long-range motor-motor interactions mediated by circuit voltage and electrical power flows result in coexistence and segregation of spatially extended phases defined by individual motor states, a "normal" state where the motors' mechanical (rotation) frequency is slightly smaller than the nominal frequency of the basic ac flows and a "stalled" state where the mechanical frequency is small. Transitions between the two states can be initiated by a perturbation of the voltage or base frequency at the head of the distribution feeder. Such behavior is typical of first-order phase transitions in physics, and this 1+1 dimensional model shows many other properties of a first-order phase transition with the spatial distribution of the motors' mechanical frequency playing the role of the order parameter. In particular, we observe (a) propagation of the phase-transition front with the constant speed (in very long feeders) and (b) hysteresis in transitions between the normal and stalled (or partially stalled) phases. PMID:23848724
Hysteresis of Soil Point Water Retention Functions Determined by Neutron Radiography
NASA Astrophysics Data System (ADS)
Perfect, E.; Kang, M.; Bilheux, H.; Willis, K. J.; Horita, J.; Warren, J.; Cheng, C.
2010-12-01
Soil point water retention functions are needed for modeling flow and transport in partially-saturated porous media. Such functions are usually determined by inverse modeling of average water retention data measured experimentally on columns of finite length. However, the resulting functions are subject to the appropriateness of the chosen model, as well as the initial and boundary condition assumptions employed. Soil point water retention functions are rarely measured directly and when they are the focus is invariably on the main drying branch. Previous direct measurement methods include time domain reflectometry and gamma beam attenuation. Here we report direct measurements of the main wetting and drying branches of the point water retention function using neutron radiography. The measurements were performed on a coarse sand (Flint #13) packed into 2.6 cm diameter x 4 cm long aluminum cylinders at the NIST BT-2 (50 ?m resolution) and ORNL-HFIR CG1D (70 ?m resolution) imaging beamlines. The sand columns were saturated with water and then drained and rewetted under quasi-equilibrium conditions using a hanging water column setup. 2048 x 2048 pixel images of the transmitted flux of neutrons through the column were acquired at each imposed suction (~10-15 suction values per experiment). Volumetric water contents were calculated on a pixel by pixel basis using Beer-Lambert’s law in conjunction with beam hardening and geometric corrections. The pixel rows were averaged and combined with information on the known distribution of suctions within the column to give 2048 point drying and wetting functions for each experiment. The point functions exhibited pronounced hysteresis and varied with column height, possibly due to differences in porosity caused by the packing procedure employed. Predicted point functions, extracted from the hanging water column volumetric data using the TrueCell inverse modeling procedure, showed very good agreement with the range of point functions measured within the column using neutron radiography. Extension of these experiments to 3-dimensions using neutron tomography is planned.
Hysteresis, phase transitions, and dangerous transients in electrical power distribution systems
NASA Astrophysics Data System (ADS)
Duclut, Charlie; Backhaus, Scott; Chertkov, Michael
2013-06-01
The majority of dynamical studies in power systems focus on the high-voltage transmission grids where models consider large generators interacting with crude aggregations of individual small loads. However, new phenomena have been observed indicating that the spatial distribution of collective, nonlinear contribution of these small loads in the low-voltage distribution grid is crucial to the outcome of these dynamical transients. To elucidate the phenomenon, we study the dynamics of voltage and power flows in a spatially extended distribution feeder (circuit) connecting many asynchronous induction motors and discover that this relatively simple 1+1 (space+time) dimensional system exhibits a plethora of nontrivial spatiotemporal effects, some of which may be dangerous for power system stability. Long-range motor-motor interactions mediated by circuit voltage and electrical power flows result in coexistence and segregation of spatially extended phases defined by individual motor states, a “normal” state where the motors’ mechanical (rotation) frequency is slightly smaller than the nominal frequency of the basic ac flows and a “stalled” state where the mechanical frequency is small. Transitions between the two states can be initiated by a perturbation of the voltage or base frequency at the head of the distribution feeder. Such behavior is typical of first-order phase transitions in physics, and this 1+1 dimensional model shows many other properties of a first-order phase transition with the spatial distribution of the motors’ mechanical frequency playing the role of the order parameter. In particular, we observe (a) propagation of the phase-transition front with the constant speed (in very long feeders) and (b) hysteresis in transitions between the normal and stalled (or partially stalled) phases.
Rate-dependent elastic hysteresis during the peeling of pressure sensitive adhesives.
Villey, Richard; Creton, Costantino; Cortet, Pierre-Philippe; Dalbe, Marie-Julie; Jet, Thomas; Saintyves, Baudouin; Santucci, Stéphane; Vanel, Loïc; Yarusso, David J; Ciccotti, Matteo
2015-05-01
The modelling of the adherence energy during peeling of Pressure Sensitive Adhesives (PSA) has received much attention since the 1950's, uncovering several factors that aim at explaining their high adherence on most substrates, such as the softness and strong viscoelastic behaviour of the adhesive, the low thickness of the adhesive layer and its confinement by a rigid backing. The more recent investigation of adhesives by probe-tack methods also revealed the importance of cavitation and stringing mechanisms during debonding, underlining the influence of large deformations and of the related non-linear response of the material, which also intervenes during peeling. Although a global modelling of the complex coupling of all these ingredients remains a formidable issue, we report here some key experiments and modelling arguments that should constitute an important step forward. We first measure a non-trivial dependence of the adherence energy on the loading geometry, namely through the influence of the peeling angle, which is found to be separable from the peeling velocity dependence. This is the first time to our knowledge that such adherence energy dependence on the peeling angle is systematically investigated and unambiguously demonstrated. Secondly, we reveal an independent strong influence of the large strain rheology of the adhesives on the adherence energy. We complete both measurements with a microscopic investigation of the debonding region. We discuss existing modellings in light of these measurements and of recent soft material mechanics arguments, to show that the adherence energy during peeling of PSA should not be associated to the propagation of an interfacial stress singularity. The relevant deformation mechanisms are actually located over the whole adhesive thickness, and the adherence energy during peeling of PSA should rather be associated to the energy loss by viscous friction and by rate-dependent elastic hysteresis. PMID:25791135
Torpor and hypothermia: reversed hysteresis of metabolic rate and body temperature.
Geiser, Fritz; Currie, Shannon E; O'Shea, Kelly A; Hiebert, Sara M
2014-12-01
Regulated torpor and unregulated hypothermia are both characterized by substantially reduced body temperature (Tb) and metabolic rate (MR), but they differ physiologically. Although the remarkable, medically interesting adaptations accompanying torpor (e.g., tolerance for cold and ischemia, absence of reperfusion injury, and disuse atrophy) often do not apply to hypothermia in homeothermic species such as humans, the terms "torpor" and "hypothermia" are often used interchangeably in the literature. To determine how these states differ functionally and to provide a reliable diagnostic tool for differentiating between these two physiologically distinct states, we examined the interrelations between Tb and MR in a mammal (Sminthopsis macroura) undergoing a bout of torpor with those of the hypothermic response of a similar-sized juvenile rat (Rattus norvegicus). Our data show that under similar thermal conditions, 1) cooling rates differ substantially (approximately fivefold) between the two states; 2) minimum MR is approximately sevenfold higher during hypothermia than during torpor despite a similar Tb; 3) rapid, endogenously fuelled rewarming occurs in torpor but not hypothermia; and 4) the hysteresis between Tb and MR during warming and cooling proceeds in opposite directions in torpor and hypothermia. We thus demonstrate clear diagnostic physiological differences between these two states that can be used experimentally to confirm whether torpor or hypothermia has occurred. Furthermore, the data can clarify the results of studies investigating the ability of physiological or pharmacological agents to induce torpor. Consequently, we recommend using the terms "torpor" and "hypothermia" in ways that are consistent with the underlying regulatory differences between these two physiological states. PMID:25253085
NASA Astrophysics Data System (ADS)
Lucarini, Valerio; Fraedrich, Klaus; Lunkeit, Frank
2010-05-01
We present an extensive thermodynamic analysis of a hysteresis experiment performed on a simplified yet Earth-like climate model. We slowly vary the solar constant by 20% around the present value and detect that for a large range of values of the solar constant the realization of snowball or of regular climate conditions depends on the history of the system. Using recent results on the global climate thermodynamics, we show that the two regimes feature radically different properties. The efficiency of the climate machine monotonically increases with decreasing solar constant in present climate conditions, whereas the opposite takes place in snowball conditions. Instead, entropy production is monotonically increasing with the solar constant in both branches of climate conditions, and its value is about four times larger in the warm branch than in the corresponding cold state. Finally, the degree of irreversibility of the system, measured as the fraction of excess entropy production due to irreversible heat transport processes, is much higher in the warm climate conditions, with an explosive growth in the upper range of the considered values of solar constants. Whereas in the cold climate regime a dominating role is played by changes in the meridional albedo contrast, in the warm climate regime changes in the intensity of latent heat fluxes are crucial for determining the observed properties. This substantiates the importance of addressing correctly the variations of the hydrological cycle in a changing climate. An interpretation of the climate transitions at the tipping points based upon macro-scale thermodynamic properties is also proposed. Our results support the adoption of a new generation of diagnostic tools based on the 2nd law of thermodynamics for auditing climate model and outline a set of parameterizations to be used in conceptual and intermediate complexity models or for the reconstruction of the past climate conditions