Sample records for hysteresis curve shows

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

    USGS Publications Warehouse

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

    2014-01-01

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

  2. Introducing Hysteresis in Snow Depletion Curves to Improve the Water Budget of a Land Surface Model in an Alpine Catchment

    E-print Network

    Introducing Hysteresis in Snow Depletion Curves to Improve the Water Budget of a Land Surface Model), a distributed land surface model (LSM) with a multilayer, physically based snow model, has been applied of the accu- mulation and ablation of the snow cover using Moderate Resolution Imaging Spectroradiometer

  3. 60. SUPPORT CARRIAGE ASSEMBLY AT ISLIP CANYON SHOWING CURVED RAILS ...

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

    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

  4. Modeling hysteresis curves of anisotropic SmCoFeCuZr magnets

    NASA Astrophysics Data System (ADS)

    Sampaio da Silva, Fernanda A.; Castro, Nicolau A.; de Campos, Marcos F.

    2013-02-01

    The hysteresis curves at room temperature and at 630 K of an anisotropic magnet were successfully modeled with the Stoner-Wohlfarth Callen-Liu-Cullen (SW-CLC) model. This implies that coherent rotation of domains is the reversal mechanism in this magnet. The chemical composition of the evaluated magnet is Sm(CobalFe0.06Cu0.108Zr0.03)7.2. The anisotropy field HA was estimated with the model, resulting ?0HA=7.1 T at the room temperature, and 2.9 T at 630 K. For this sample, the CLC interaction parameter (1/d) is very low (near zero) and, thus, the nanocrystalline 2:17 grains are well "magnetically decoupled". The texture analysis using Schulz Pole figure data indicated Mr/Ms ratio=0.96, and this means that the magnet is very well aligned. The excellent alignment of the grains is one of the reasons for the high coercivity of this sample (˜4 T at room temperature).

  5. 14. VIEW FROM TUNDRA CURVES (ON TRAIL RIDGE ROAD) SHOWING ...

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

    14. VIEW FROM TUNDRA CURVES (ON TRAIL RIDGE ROAD) SHOWING FALL RIVER ROAD RISING FROM BENEATH CHAPIN PASS (AT EXTREME RIGHT) TO FALL RIVER PASS (FAR LEFT). - Fall River Road, Between Estes Park & Fall River Pass, Estes Park, Larimer County, CO

  6. Experimental methodology to measure damping in microstructures by using the actuation force hysteresis curve

    NASA Astrophysics Data System (ADS)

    De Pasquale, G.; Somá, A.

    2013-05-01

    The study of damping in MEMS (micro electro-mechanical systems) is crucial for dynamic response prediction and functional parameters estimation as switch and release time, resonance and quality factor. Geometrical features (borders, perforations, anchors, etc.) complicate the airflow and impose to validate the results calculated or simulated with models. Fluid damping is the dominant dissipation source, accompanied by structural dissipations, thermo-elastic damping, anchor losses, surface effects and electric losses. In literature, the damping coefficient of MEMS is generally derived from the peaks of the structural frequency response function (FRF) by the half power method. Despite the wide usage of this approach, it is affected by two main drawbacks: highly precise and automated detection instruments are needed, and it is applicable only in resonance conditions. The method presented here is based on the measurement of damping from the hysteresis cycle of the actuation force; it applies in the time domain and works at any frequency and vibration amplitude. The effectiveness of this methodology on MEMS is proved by comparing the damping results with those provided at resonance conditions by the half power method. The samples, designed by the authors, are gold microplates with square holes and elastic springs. The measurements are conducted by the laser vibrometer Polytech MSA500. The comparison shows very good agreement with the damping coefficients calculated with the traditional approach (differences within 2% at resonance).

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

    Microsoft Academic Search

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

    1995-01-01

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

  8. Effect of the magnetic field applied during cooling on magnetic hysteresis in the low-temperature phase of magnetite: First-order reversal curve (FORC) analysis

    Microsoft Academic Search

    A. V. Smirnov

    2007-01-01

    The strength of a magnetic field applied during cooling through the Verwey transition can control the low-temperature (LT) magnetic hysteresis properties of magnetite. This effect is investigated using the first-order reversal curve (FORC) technique. LT FORC distributions were measured at 20 K from four polycrystalline samples after cooling from 300 K in zero magnetic field or in the presence of

  9. Mon. Not. R. Astron. Soc. 338, 189196 (2003) Hysteresis in the light curves of soft X-ray transients

    E-print Network

    Coppi, Paolo

    the hard-to-soft transition. This hysteresis effect rules out the propeller mechanism as the sole cause of state transitions in Aql X-1. Assuming the propeller mechanism only operates at a luminosity equal energies with no apparent cut-off. The radiation mechanisms in the very high state are not as well un

  10. Mon. Not. R. Astron. Soc. 338, 189--196 (2003) Hysteresis in the light curves of soft Xray transients

    E-print Network

    Coppi, Paolo

    at a luminosity #5 times lower than the hard­to­soft transition. This hysteresis effect rules out the propeller mechanism as the sole cause of state transitions in Aql X­1. Assuming the propeller mechanism only operates­off. The radiation mechanisms in the very high state are not as well un­ derstood as in the other states. There also

  11. Design model of the FNPB guide system showing the curved cold beam with four

    E-print Network

    Pennycook, Steve

    Design model of the FNPB guide system showing the curved cold beam with four frame overlap choppers, as well as the monochromator housing and the ballistic ultracold neutron guide. The cold guide and choppers share a common vacuum to reduce window losses. For more information, contact Project Manager

  12. Hysteresis and threshold switching characteristics in thin-film-transistors with inserted Pt-Fe2O3 core–shell nanocrystals

    NASA Astrophysics Data System (ADS)

    Baek, Yoon-Jae; Noh, Young Jun; Choi, Young Jin; Kang, Chi Jung; Lee, Hyun Ho; Yoon, Tae-Sik

    2014-11-01

    Hysteresis and threshold switching characteristics were investigated in the indium-gallium-zinc-oxide (IGZO) thin-film-transistors (TFTs) with inserted Pt-Fe2O3 core–shell nanocrystals (NCs) layer between source/drain and IGZO channel. The output curves showed the hysteresis with threshold drain voltage and the transfer curves showed the hysteresis with the shift of threshold gate voltage. These hysteresis, threshold switching, and shift of threshold voltage in both output and transfer curves are caused by charging of inserted NCs. These unique features demonstrated the memory and on/off switching operation by controlling both threshold gate and drain voltages through charging NCs.

  13. Rate-dependent light-induced thermal hysteresis of [Fe(PM-BiA)2(NCS)2] spin transition complex

    NASA Astrophysics Data System (ADS)

    Enachescu, Cristian; Tanasa, Radu; Stancu, Alexandru; Chastanet, Guillaume; Létard, Jean-François; Linares, Jorge; Varret, François

    2006-04-01

    The light-induced bistability under permanent irradiation (LITH: light-induced thermal hysteresis), due to the competition between light irradiation and self-accelerated relaxation, shows crucially rate-dependent hysteresis. Major and minor hysteresis loops for [Fe(PM-BiA)2(NCS)2] spin crossover compound have been measured. Using appropriate master equations, distribution data from the first-order reversal curves diagrams of the purely thermal hysteresis, and parameter values previously derived from relaxation curves, we could simulate the LITH experimental data. The tunneling contribution to the relaxation rate revealed to be a key factor for the final agreement.

  14. Plant thermal hysteresis proteins.

    PubMed

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

    1992-05-22

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

  15. Venous Grafts Procured During the Learning Curve for Endoscopic Veins Harvesting Show Compromised Vascular Remodeling

    PubMed Central

    Kiani, Soroosh; Desai, Pranjal H.; Thirumvalavan, Nannan; Kurian, Dinesh John; Flynn, Mary Margaret; Zhao, XiaoQing

    2011-01-01

    BACKGROUND Endoscopic vein harvest (EVH) is the US standard of care for CABG but recent comparisons to open harvest suggest that conduit quality and outcomes may be compromised. To test the hypothesis that problems with EVH may relate to its learning curve and conduit quality, we analyzed the quality and early function of conduits procured by technicians with varying EVH experience. METHODS EVH was performed during CABG by “experienced” (>900 cases, n=55 patients) vs. “novice” (<100 cases, n=30 patients) technicians. Afterwards, conduits were and examined for vascular injury using optical coherence tomography (OCT), with segments identified as injured further examined for gene expression using a tissue injury array. Conduit diameter was measured intra- and postoperatively (day 5 and 6 months) using OCT and Computed-Tomography angiography. RESULTS EVH performed by novice harvesters resulted in increased number of discrete graft injuries and higher expression of tissue injury genes. Regression analysis revealed an association between shear stress and early dilation (positive remodeling) (R2 =0.48, p <0.01). Injured veins showed blunted positive remodeling at 5 days and a greater degree of late lumen loss at 6 months. CONCLUSION Under normal conditions, intraluminal shear stress leads vein grafts to develop positive remodeling over the first postoperative week. Injury to conduits, a frequent sequela of the learning curve for EVH, was a predictor of early graft failure, blunted positive remodeling and greater negative remodeling. Given the ongoing annual volume of EVH cases, rigorous monitoring of the learning curve represents an important and unrecognized public health issue. PMID:21996436

  16. A magnetic hysteresis model

    NASA Technical Reports Server (NTRS)

    Flatley, Thomas W.; Henretty, Debra A.

    1995-01-01

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

  17. MOST light-curve analysis of the ? Doradus pulsator HR 8799, showing resonances and amplitude variations

    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.

  18. Design of experiment for hysteresis loops measurement

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

  1. Contact angle hysteresis on fluoropolymer surfaces.

    PubMed

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

    2007-10-31

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

  2. A simple model of hysteresis behavior using spreadsheet analysis

    NASA Astrophysics Data System (ADS)

    Ehrmann, A.; Blachowicz, T.

    2015-01-01

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

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

    PubMed

    Park, Jongkyu; Moon, Wonkyu

    2010-03-01

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

  4. 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.

  5. Theory of molecular hysteresis switch

    NASA Astrophysics Data System (ADS)

    Kozhushner, Mortko; Oleynik, Ivan

    2006-03-01

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

  6. Magnetoimpedance hysteresis in amorphous microwires induced by core-shell interaction

    NASA Astrophysics Data System (ADS)

    Ipatov, M.; Zhukova, V.; Gonzalez, J.; Zhukov, A.

    2014-09-01

    We report on magneto-impedance (MI) hysteresis at MHz and GHz frequencies in amorphous microwires subject to a sufficiently high applied axial magnetic field HE. We show that this hysteresis originates from the magnetic hysteresis of the inner core which biases the outer shell causing a shift of the MI curve along the HE axis. Combined experiments (longitudinal and off-diagonal MI Z(HE), hysteresis loops M(HE) by vibrating sample magnetometer, and induction method) reveal the details of the magnetization reversal process in these microwires: Partial field dependencies Z(HE) and M(HE) are shown to be practically anhysteretic but shifted to the left or to the right about the origin by a residual magnetic field of the inner core HC. This shift can vary in the range from -35 to +35 A/m, depending on the magnetic history of the sample. We demonstrate that the hysteresis can be suppressed by application of a high enough axial magnetic field that saturates the magnetization of the inner core. A potential application of this hysteresis for memory devices is also proposed.

  7. 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).

  8. Efficient Computational Model of Hysteresis

    NASA Technical Reports Server (NTRS)

    Shields, Joel

    2005-01-01

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

  9. Mathematical models of hysteresis

    Microsoft Academic Search

    I. Mayergoyz

    1986-01-01

    A new approach to Preisach's hysteresis model, which emphasizes its phenomenological nature and mathematical generality, is briefly described. Then the theorem which gives the necessary and sufficient conditions for the representation of actual hysteresis nonlinearities by Preisach's model is proven. The significance of this theorem is that it establishes the limits of applicability of this model.

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

    Microsoft Academic Search

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

    2005-01-01

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

  11. 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.

  12. Corneal hysteresis and its relevance to glaucoma

    PubMed Central

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

    2015-01-01

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

  13. Hysteresis in column systems

    NASA Astrophysics Data System (ADS)

    Ivanyi, P.; Ivanyi, A.

    2015-02-01

    In this paper one column of a telescopic construction of a bell tower is investigated. The hinges at the support of the column and at the connecting joint between the upper and lower columns are modelled with rotational springs. The characteristics of the springs are assumed to be non-linear and the hysteresis property of them is represented with the Preisach hysteresis model. The mass of the columns and the bell with the fly are concentrated to the top of the column. The tolling process is simulated with a cycling load. The elements of the column are considered completely rigid. The time iteration of the non-linear equations of the motion is evaluated by the Crank-Nicolson schema and the implemented non-linear hysteresis is handled by the fix-point technique. The numerical simulation of the dynamic system is carried out under different combination of soft, medium and hard hysteresis properties of hinges.

  14. Structural hysteresis model of transmitting mechanical systems

    NASA Astrophysics Data System (ADS)

    Ruderman, M.; Bertram, T.

    2015-02-01

    We present a structural hysteresis model which describes the dynamic behavior of transmitting mechanical systems with a hysteretic spring and damped bedstop element, both connected in series. From the application point view this approach can be used for predicting the transmitted mechanical force based only on the known kinematic excitation. Using the case study of an elastic gear transmission we show and identify a hysteresis response which multivariate behavior depends on an internal state of the bedstop motion.

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

    SciTech Connect

    Lin, H.J.; Chen, C.T.; Meigs, G. [AT and T Bell Labs., Murray Hill, NJ (United States); Idzerda, Y.U.; Chaiken, A.; Prinz, G.A. [Naval Research Lab., Washington, DC (United States); Ho, G.H. [Pennsylvania Univ., Philadelphia, PA (United States). Dept. of Physics

    1993-09-07

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

  16. Dynamic hysteresis modelling

    NASA Astrophysics Data System (ADS)

    Zirka, S. E.; Moroz, Y. I.; Marketos, P.; Moses, A. J.

    2004-01-01

    A viscous-type dynamic hysteresis model (DHM) is developed. The DHM is compatible with static underlying model of any type and nature (Preisach or non-Preisach). The distinguishing features of the DHM are its arbitrary frequency dependence and the ability to control the shape of the dynamic hysteresis loop. The numerical method for the incorporation of the DHM in magnetodynamic computations is illustrated by a good agreement of modelled dynamic loops with measured loops of non-oriented and grain-oriented electrical steels.

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

    SciTech Connect

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

    2010-01-01

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

  18. 51A Simple Model for Atmospheric Carbon Dioxide The graph to the left shows the 'Keeling Curve' which plots the increase in

    E-print Network

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

  19. The extrinsic hysteresis behavior of dilute binary ferrofluids.

    PubMed

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

    2014-10-01

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

  20. Modeling concentration-dependent sorption-desorption hysteresis of atrazine in a loam soil.

    PubMed

    Anagu, Ihuaku; Ingwersen, Joachim; Drori, Yaron; Chefetz, Benny; Streck, Thilo

    2011-01-01

    Nonequilibrium sorption plays an active role in the transport of organic contaminants in soil. We applied a two-stage, one-rate model (2S1R) and a new, nonlinear variant (2S1RN) of this model to examine the effects of wastewater irrigation on the sorption kinetics of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) in soil. The models were applied to previously published sorption-desorption data sets, which showed pronounced deviations between sorption curves and desorption curves (sorption-desorption hysteresis). Moreover, the slopes of the desorption curves decreased with decreasing concentration. Different treatments had been used, and two experimental time steps (2 and 14 d) were used. Treatments considered were lipid removal, fulvic and humic acid removal, and untreated soil. The 2S1R model was unable to reproduce the observed type of hysteresis, but the 2S1RN model, which assumes that the sorption-desorption process follows a power function relationship, was able to reproduce the observed type of hysteresis. Visually, applying the new model improved the model fits in all test cases. Statistically, as tested by an extra sum of squares analysis, the new model performed significantly better in 50% of all test cases. According to an example simulation, the choice of the sorption model has a considerable impact on the prediction of atrazine transport in soil. PMID:21520761

  1. Hysteresis of ionization waves

    SciTech Connect

    Dinklage, A. [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Association, Wendelsteinstr. 1, 17491 Greifswald (Germany); Bruhn, B.; Testrich, H. [Institut fuer Physik, E.-M.-Arndt Universitaet Greifswald, Felix-Hausdorff-Str. 6, 17487 Greifswald (Germany); Wilke, C. [Leibniz-Institut fuer Plasmaforschung und Technologie, Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany)

    2008-06-15

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

  2. Positive hysteresis of Ce-doped GAGG scintillator

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  3. Capillary Condensation in Porous Materials. Hysteresis and Interaction Mechanism without Pore Blocking/Percolation Process

    E-print Network

    Paris-Sud XI, Université de

    Capillary Condensation in Porous Materials. Hysteresis and Interaction Mechanism without Pore loops, reversal curves, and subloops in p+-type porous silicon, a porous material composed of straight hysteresis loops which depends on the porous material (H1 for MCM-41 and SBA-15, H2 for porous glass and p

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  5. Macroscopic theory for capillary-pressure hysteresis.

    PubMed

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

    2015-03-01

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

  6. Hysteresis and coercivity of hematite

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Dunlop, D. J.

    2008-12-01

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

  8. Ac magnetorestriction hysteresis and magnetization direction in grain oriented silicon steels

    SciTech Connect

    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.

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

    SciTech Connect

    Albin, D.; del Cueto, J.

    2011-03-01

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

  10. Mach, methodology, hysteresis and economics

    NASA Astrophysics Data System (ADS)

    Cross, R.

    2008-11-01

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

  11. Hysteresis modeling in ballistic carbon nanotube field-effect transistors

    PubMed Central

    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

  12. Hysteresis compensation in PZT bimorph mirrors: Preisach's classical and non-linear models

    NASA Astrophysics Data System (ADS)

    Dubra, Alfredo; Massa, John S.; Paterson, Carl

    2005-12-01

    A number of reflective wavefront correctors used in adaptive optics are based on the use of piezoelectric effect, either in piston, tip/tilt or curvature devices. The relation between the voltage applied to drive these devices and the mechanical response always presents hysteresis to some extent. In this work we study the performance of Preisach's classical and non-linear models of hysteresis on a bimorph mirror, which is a curvature device, but both models can also be applied to piston and tip/tilt devices. Bimorph mirrors with PZT actuators and a passive glass substrate were tested in an adaptive optics test-bed (AOTB) using a Shack-Hartmann wavefront sensor. First- and second-order reversal curves were sampled uniformly in Preisach space, and interpolation algorithms were implemented to test Preisach's classical and non-linear forward models respectively. Then, arbitrary voltage configuration sequences were applied to the mirror and the responses were recorded. Finally, the inversion of the models was implemented and included in the AOTB linear control algorithm to test the closed-loop performance. We found that both hysteresis models provide a similar improvement in the open-loop error. The improvement estimation depends on the particular sequence applied, the number of samples of the Preisach function and noise among other factors. Finally, we present data showing that the hysteretic behavior in a multi-electrode mirror is, within experimental error, independent of the electrode geometry, area and location.

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

    PubMed

    Duman, J G

    1994-05-18

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

  14. Rotational hysteresis of exchange-spring magnets.

    SciTech Connect

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

    2002-03-27

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

  15. Stage-Discharge Hysteresis and Bedforms (Invited)

    NASA Astrophysics Data System (ADS)

    Nelson, J. M.; Giri, S.; Shimizu, Y.; Nabi, M.; McDonald, R.

    2013-12-01

    One of the most commonly-cited (and earliest recorded) examples of hysteresis in geomorphology and hydraulics is that arising in river stage-discharge rating curves, where different stages occur on the rising and falling limbs of a hydrograph for the same discharge. This is typically attributed to bedform dynamics, particularly in the case where bedforms disappear during increasing flows due to high Froude numbers and/or suspended load and are subsequently reformed on the falling limb of the hydrograph. In that case, the effective form drag of the bedforms is significantly different for the same discharge, as the bedforms have very different shapes on the rising and falling limb. Although the effect is most noticeable in the case where bedforms 'wash out', it is important to realize that the same effects give rise to weaker forms of hysteresis even when bedforms are uniformly present but evolve in response to changing flows. In this presentation, examples of both strong and weak hysteresis are shown using results from two- and three-dimensional mobile bed models which directly resolve the pressure distribution on the bed (and hence the form drag on bed features). Computations are compared to laboratory measurements of bedform behavior to support the use of such computations for predicting bedform behavior in rapidly varying flows. To connect this to more practical computations for larger-scale rivers, we describe a straightforward method for combining bedform dynamics calculations with much coarser planform river models in order to include the effect of bedform shape changes on effective bed roughness. Results from this method are shown for the Kootenai River in Northern Idaho. These results support the use of this hybrid technique when models capable of resolving bedform mechanics are impractical.

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

    E-print Network

    Romensky, Maksym

    2015-01-01

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

  17. Dynamic Hysteresis in Compacted Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Chowdary, Krishna M.

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

  18. Comparative experiments regarding approaches to feedforward hysteresis compensation for piezoceramic actuators

    NASA Astrophysics Data System (ADS)

    Gu, Guo-Ying; Zhu, Li-Min

    2014-09-01

    Piezoceramic actuators (PCAs) are desired devices in many micro/nano-positioning applications. The performance of PCA-based applications is severely limited by the presence of hysteresis nonlinearity. To remedy the hysteresis nonlinearity in such systems, feedforward hysteresis compensation is the most common technique. In the literature, many different feedforward hysteresis compensation approaches have been developed, but there are no comparative studies of these approaches. Focusing on the modified Prandtl-Ishlinskii model (MPIM) for asymmetric hysteresis description of piezoceramic actuators, three feedforward hysteresis compensation approaches—inverse hysteresis compensation (IHC), without inverse hysteresis compensation (WIHC), and direct inverse hysteresis compensation (DIHC)—are developed and compared in this paper. Extensive comparative experiments were conducted on a PCA-actuated stage to verify the effectiveness of the three different feedforward control approaches to hysteresis compensation. The experimental results show that the performances among the three approaches are rather similar, and the main differences among them are due to the specific implementation of each approach.

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

    SciTech Connect

    Wojcik, Tadeusz Michal [Department of Heat Engineering, Kielce University of Technology, Al. Tysiaclecia P.P.7, 25-314 Kielce (Poland)

    2009-03-15

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

  20. Intercrystalline magnetic interaction and hysteresis characteristics of high-coercivity cobalt-based alloy coatings

    Microsoft Academic Search

    V. G. Shadrov; A. E. Dmitrieva; L. V. Nemtsevich

    2011-01-01

    ?M(H) curves and the time dependences of the magnetization and the rotational hysteresis losses are used to analyze the effect\\u000a of intercrystalline magnetic interaction on the magnetization reversal and the hysteresis characteristics of nanostructured\\u000a cobalt-based alloy coatings, which manifest themselves in a change in the relations between the rotation and displacement\\u000a of reversible and irreversible processes and between thermally activated

  1. 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.

  2. RBF neural networks hysteresis modelling for piezoceramic actuator using hybrid model

    NASA Astrophysics Data System (ADS)

    Dang, Xuanju; Tan, Yonghong

    2007-01-01

    An radial basis function (RBF) neural networks rate-dependent hysteresis hybrid model for piezoceramic actuator is proposed. The piezoceramic actuator cannot be described by neural networks like the back propagation (BP) static neural networks because of its multi-valued hysteresis non-linearity. The proposed hybrid hysteresis model consists of hysteresis-like non-linearity in series with a dynamic RBF neural networks used for implementing non-linear transformations of the phase lag and non-linear magnitude. The hysteresis-like non-linearity model, which is composed of the previous output of piezoceramic actuator and input signal, differs from the hysteresis behaviour of piezoceramic actuator in only ways of their phase and magnitude, and it is used to describe the non-smooth behaviour of piezoceramic actuator. The results of both simulation and experiment show that the new modelling approach is very effective and of higher precision under a decayed input signal with the varying frequency.

  3. Hysteresis in Pressure-Driven DNA Denaturation

    PubMed Central

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

    2012-01-01

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

  4. Hysteresis in Audiovisual Synchrony Perception

    PubMed Central

    van Wassenhove, Virginie

    2015-01-01

    The effect of stimulation history on the perception of a current event can yield two opposite effects, namely: adaptation or hysteresis. The perception of the current event thus goes in the opposite or in the same direction as prior stimulation, respectively. In audiovisual (AV) synchrony perception, adaptation effects have primarily been reported. Here, we tested if perceptual hysteresis could also be observed over adaptation in AV timing perception by varying different experimental conditions. Participants were asked to judge the synchrony of the last (test) stimulus of an AV sequence with either constant or gradually changing AV intervals (constant and dynamic condition, respectively). The onset timing of the test stimulus could be cued or not (prospective vs. retrospective condition, respectively). We observed hysteretic effects for AV synchrony judgments in the retrospective condition that were independent of the constant or dynamic nature of the adapted stimuli; these effects disappeared in the prospective condition. The present findings suggest that knowing when to estimate a stimulus property has a crucial impact on perceptual simultaneity judgments. Our results extend beyond AV timing perception, and have strong implications regarding the comparative study of hysteresis and adaptation phenomena. PMID:25774653

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

    SciTech Connect

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

    2011-02-15

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

  6. Quantum Curves

    NASA Astrophysics Data System (ADS)

    Schwarz, Albert

    2015-02-01

    One says that a pair (P, Q) of ordinary differential operators specify a quantum curve if {[P,Q]=hbar} . If a pair of difference operators (K, L) obey the relation KL = q LK, where {q =e^{hbar}} , 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 {hbar} . 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).

  7. Nanomechanical Detection of Magnetic Hysteresis of a Single-crystal Yttrium Iron Garnet Micromagnetic Disk

    NASA Astrophysics Data System (ADS)

    Losby, Joseph; Diao, Zhu; Burgess, Jacob; Compton, Shawn; Fani Sani, Fatemeh; Firdous, Tayyaba; Vick, Douglas; Belov, Miro; Hiebert, Wayne; Freeman, Mark

    2013-03-01

    A micromagnetic disk was milled from a monocrystalline yttrium iron garnet film using a focused ion beam and micromanipulated onto a nanoscale torsional resonator. Nanomechanical torque magnetometry results show a unipolar magnetic hysteresis characteristic of a magnetic vortex state. Landau-Lifshitz-Gilbert-based micromagnetic simulations of the disk show a rich, flux-enclosed, three-dimensional domain structure. On the top and bottom faces of the disk, a skewed vortex state exists with a very small core. The core region extends through the thickness of the disk with a smooth variation in core diameter reaching a maximum along the midplane of the disk. The single crystalline nature of the disk lends to an observed absence of Barkhausen-like steps in the magnetization-versus-field curves, qualitatively different in comparison to the magnetometry results of an individual polycrystalline permalloy microdisk. Prospects for the mechanical detection of spin dynamical modes in these structures will also be discussed.

  8. Hysteresis from antiferromagnet domain-wall processes in exchange biased systems

    Microsoft Academic Search

    Joo-Von Kim; R. L. Stamps

    2005-01-01

    The presence of magnetic impurities in the antiferromagnet can account for some ferromagnetic hysteresis behavior observed in exchange bias systems. We show theoretically that such impurities can modify domain-wall formation in the antiferromagnet, which under certain conditions can give rise to coercivity enhancement and asymmetric hysteresis. The linear dynamics of the ferromagnet\\/antiferromagnet structure in the presence of impurities is also

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

    SciTech Connect

    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.

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

    SciTech Connect

    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.

  11. Asymmetric-hysteresis compensation in piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Aguirre, Gorka; Janssens, Thierry; Van Brussel, Hendrik; Al-Bender, Farid

    2012-07-01

    The advantages of using piezoelectric actuators in ultra-precision applications are often impaired by nonlinear effects, in particular hysteresis, which may lead to positioning uncertainties of up to 15% of the actuator's stroke. Model-based compensation strategies are often prescribed in order to overcome this limitation and achieve better dynamical accuracy. This comes, however, at the expense of increasing identification and implementation complexity, especially when hysteresis is of the asymmetric type, such as prevalent in hard piezoceramic materials. This paper proposes a new compensation strategy based upon (i) treating hysteresis as being separate from other dynamical effects and (ii) formulating a new, simplified model to deal with asymmetric hysteresis, based on applying a linear operator to the conventional hysteresis models. After developing the theoretical background of the compensation strategy, the accuracy improvement due to the new hysteresis-compensation method is demonstrated experimentally.

  12. Hysteresis in the metachronal-tripod gait transition of insects: A modeling study

    NASA Astrophysics Data System (ADS)

    Fujiki, Soichiro; Aoi, Shinya; Funato, Tetsuro; Tomita, Nozomi; Senda, Kei; Tsuchiya, Kazuo

    2013-07-01

    Locomotion in biological systems involves various gaits, and hysteresis appears when the gaits change in accordance with the locomotion speed. That is, the gaits vary at different locomotion speeds depending on the direction of speed change. Although hysteresis is a typical characteristic of nonlinear dynamic systems, the underlying mechanism for the hysteresis in gait transitions remains largely unclear. In this study, we construct a neuromechanical model of an insect and investigate the dynamic characteristics of its gait and gait transition. The simulation results show that our insect model produces metachronal and tripod gaits depending on the locomotion speed through dynamic interactions among the body mechanical system, the nervous system, and the environment in a self-organized manner. They also show that it undergoes the metachronal-tripod gait transition with hysteresis by changing the locomotion speed. We examined the hysteresis mechanism in the metachronal-tripod gait transition of insects from a dynamic viewpoint.

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

    NASA Astrophysics Data System (ADS)

    Patros, T.

    2011-12-01

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

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

    E-print Network

    Falko Ziebert; Hervé Mohrbach; Igor M. Kuli?

    2014-05-18

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

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

    SciTech Connect

    Professor Isaak Mayergoyz

    2006-08-21

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

  16. Control of hysteresis: theory and experimental results

    Microsoft Academic Search

    Xiaobo Tan; P. S. Krishnaprasad; Wright-Patterson AF

    Hysteresis in smart materials hinders the wider applicability of such materials in actuators. In this paper, a systematic approach for coping with hysteresis is presented. The method is illustrated through the example of controlling a commercially available magnetostrictive actuator. We utilize the low-dimensional model for the magnetostrictive actuator that was developed in earlier work. For low frequency inputs, the model

  17. How small is pedogenic magnetite? Size estimates for loessic soils based on remanence and hysteresis measurements.

    NASA Astrophysics Data System (ADS)

    Geiss, C. E.; Machac, T.

    2005-12-01

    Pedogenic magnetite (or maghemite) is generally believed to be fine-grained, consisting mainly of superparamagnetic (SP) and single-domain (SD) particles. These grain size estimates are based on increased values of ARM/IRM or frequency dependent susceptibility (?FD) in the magnetically enhanced horizons. However, these changes in grain size dependent parameters are generally quite small, compared to the often large increase in concentration dependent parameters, such as low field susceptibility, saturation magnetization (J_S), or various remanence parameters (RM). In addition, a recent study by Dunlop (2002b) suggested that hysteresis properties of several Chinese soils (modern and buried) do not suggest a fining of the magnetic component in the magnetically enhanced soil horizons. We used the model of Dunlop (2002a)to analyze hysteresis data from twenty modern soil profiles from the Midwestern United States. In contrast to the data analyzed by Dunlop (2002b), our data can be modeled equally well with binary mixtures of SD-MD and SD-SP particles. To complement the ambiguous hysteresis data we generated a simple mixing model to constrain the size distribution of pedogenic magnetite. Our model assumes remanence acquisition efficiencies f = RM / J_S for coarse (MD - PSD) and fine (SD-SP) magnetite for ARM and IRM. It then uses ARM/IRM ratios to estimate the relative abundances of coarse and fine magnetite. The validity of our grain size distribution estimates can be checked by comparing measured J_S values to J_S calculated from our model output and measured values of IRM (or ARM). A comparison of our ARM/IRM modeling and hysteresis data shows that the magnetic properties of magnetically enhanced soil horizons can be explained with the addition of a fine grained magnetite component. This component, however, has a wide grain size distribution which includes SP, SD and likely PSD particles. Dunlop, D. J. (2002a). Theory and application of the Day plot (Mrs/M_s versus Hcr/H_c) 1. Theoretical curves and tests using titanomagnetite data. Journal of Geophysical Research 107, 10.1029/2001JB000486. Dunlop, D. J. (2002b). Theory and application of the Day plot (Mrs/M_s versus Hcr/H_c) 2. Application to data for rocks, sediments and soils. Journal of Geophysical Research 107, 10.1029/2001JB000487.

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

    Microsoft Academic Search

    Emmanuel Vagaggini; Jean-Marc Domergue; Anthony G. Evans

    1995-01-01

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

  19. Model for the effect of tensile and compressive stress on ferromagnetic hysteresis

    NASA Astrophysics Data System (ADS)

    Sablik, M. J.; Kwun, H.; Burkhardt, G. L.; Jiles, D. C.

    1987-04-01

    A model is presented for the stress-dependent effective field, which when used in conjunction with the Jiles-Atherton theory, qualitatively accounts for (1) the change in slope and shape of the hysteresis curves with uniaxial stress and (2) the convexity of the curves depicting remanent and peak magnetization as a function of stress. Also, the model can produce the Villari reversal if parameters are selected appropriately.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  1. Contact Angle Hysteresis on Superhydrophobic Stripes

    E-print Network

    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 $\\phi_S\\leq 0.2$.

  2. Hysteresis in In2O3:Zn nanowire field-effect transistor and its application as a nonvolatile memory device

    NASA Astrophysics Data System (ADS)

    Zhang, Wenfeng; Jie, Jiansheng; Luo, Linbao; Yuan, Guodong; He, Zhubing; Yao, Zhiqiang; Chen, Zhenhua; Lee, Chun-Sing; Zhang, Wenjun; Lee, Shuit-Tong

    2008-11-01

    Control and utilization of hysteresis in nanodevices is an important issue. In this paper, we show an enormous hysteresis in zinc-doped In2O3 nanowire field-effect transistors. Various measurements including changing the operating atmosphere, ozone treatment, and surface passivation were performed to understand and control the hysteresis. The hysteresis could be readily controlled by modifying the nanowire surface. Utilizing the hysteresis, the as-fabricated devices can function as nonvolatile memory elements with high charge storage stability exceeding 4 h. We propose that chemical species such as water molecules adsorbed on the devices and surface oxygen defects in the amorphous layer mainly originated from Zn2+ substitution of In3+ are the main causes of the large hysteresis and the nonvolatile memory effect.

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

    SciTech Connect

    Bazghaleh, Mohsen, E-mail: mohsen.bazghaleh@adelaide.edu.au; Grainger, Steven; Cazzolato, Ben; Lu, Tien-Fu [School of Mechanical Engineering, The University of Adelaide, North Terrace, South Australia 5005 (Australia)] [School of Mechanical Engineering, The University of Adelaide, North Terrace, South Australia 5005 (Australia); Oskouei, Reza [School of Computer Science, Engineering and Mathematics, Flinders University, Bedford Park, South Australia 5042 (Australia)] [School of Computer Science, Engineering and Mathematics, Flinders University, Bedford Park, South Australia 5042 (Australia)

    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.

  4. Adsorption-desorption Hysteresis of Kr and Xe on the Surface of an Ag Single Crystal

    NASA Astrophysics Data System (ADS)

    Hamada, Nozomu; Moto, Shuichi; Nakazawa, Jun; Miura, Takashi; Arakawa, Ichiro

    The isotherms and the isobars of krypton and xenon physisorbed on a silver single crystal surface were investigated by ellipsometric observation of the amount of adsorption. It was found that they showed a hysteresis in an adsorption-desorption loop for both the first and the second layer condensations. Careful examination of the effect of instability of an equilibrium pressure and a substrate temperature during the measurement revealed that they were not responsible for hysteresis. The observed hysteresis is very likely to be intrinsic one though its origin and mechanism are unknown.

  5. A new simple asymmetric hysteresis operator and its application to inverse control of piezoelectric actuators.

    PubMed

    Badel, A; Qiu, J; Nakano, T

    2008-05-01

    Piezoelectric actuators (PEAs) are commonly used as micropositioning devices due to their high resolution, high stiffness, and fast frequency response. Because piezoceramic materials are ferroelectric, they fundamentally exhibit hysteresis behavior in their response to an applied electric field. The positioning precision can be significantly reduced due to nonlinear hysteresis effects when PEAs are used in relatively long range applications. This paper describes a new, precise, and simple asymmetric hysteresis operator dedicated to PEAs. The complex hysteretic transfer characteristic has been considered in a purely phenomenological way, without taking into account the underlying physics. This operator is based on two curves. The first curve corresponds to the main ascending branch and is modeled by the function f1. The second curve corresponds to the main reversal branch and is modeled by the function g2. The functions f(1) and g(2) are two very simple hyperbola functions with only three parameters. Particular ascending and reversal branches are deduced from appropriate translations of f(1) and g(2). The efficiency and precision of the proposed approach is demonstrated, in practice, by a real-time inverse feed-forward controller for piezoelectric actuators. Advantages and drawbacks of the proposed approach compared with classical hysteresis operators are discussed. PMID:18519217

  6. Analysis of hunting in Synchronous Hysteresis Motor

    E-print Network

    Truong, Cang Kim, 1979-

    2004-01-01

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

  7. Equivalent Circuit Modeling of Hysteresis Motors

    SciTech Connect

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

    2009-08-31

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

  8. Hysteresis effects of changing the parameters of noncooperative games

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  9. Hybrid models of hysteresis for mixed hysteretic loops in heterogeneous magnetic materials

    NASA Astrophysics Data System (ADS)

    Dimian, M.; Andrei, P.; Grayson, M.

    2014-05-01

    The mixed hysteresis behavior of counter-clockwise and clockwise loops has recently attracted the attention of the magnetics community, due to several experimental findings in inhomogeneous and hetero-structure magnetic systems. Various hybrid models are proposed here to address this behavior based on the superposition of standard hysteresis models and their newly developed clockwise variants. A special attention is also devoted to Bouc-Wen model, a typical clockwise often used by applied mechanics community, and to its relevance for mixed hysteresis. These clockwise and hybrid models have been implemented in an open-access academic software and their performance is illustrated by examples of hysteretic loops, first order reversal curves and diagrams simulated in this framework.

  10. Stabilization of a system with saturating, non-monotone hysteresis and frequency dependent power losses by a PD controller

    NASA Astrophysics Data System (ADS)

    Ekanayake, D. B.; Iyer, R. V.

    2015-02-01

    We prove the closed loop stability of a PD controller for certain systems with saturating, non-monotone hysteresis and frequency dependent power losses. Most controllers use inverse compensators to cancel out actuator hysteresis nonlinearity. We show that we can achieve stability of the closed-loop system without an explicit inverse computation (using least squares minimization or otherwise).

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  12. Mechanisms of magnetic and temperature hysteresis in ErFeO3 and TmFeO3 single crystals

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

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

  13. Hysteresis and creep in powdersHysteresis and creep in powders and grainsand grains

    E-print Network

    Harting, Jens

    Hysteresis and creep in powdersHysteresis and creep in powders and grainsand grains Ciprian David. Model usedDiscrete element methods. Model used Micromechanical investigation of granular soilsMicromechanical investigation of granular soils under cyclic loadingunder cyclic loading ConclusionsConclusions #12;Motivation

  14. Hysteresis in the Central African Rainforest

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  15. Hysteresis of magnetic force-gap in static and dynamic magnetic levitation with a high-{T_c} superconductor

    NASA Astrophysics Data System (ADS)

    Gou, X.-F.; Zhang, Z.-X.

    2008-11-01

    Hysteresis behavior of magnetic force versus gap between a high-Tc superconductor and a magnet, in static and dynamic cases, is studied numerically. Differing from the previous methods, based on macro electromagnetic constitutive relation of superconductors and Maxwell equations, a numerical method with the finite element method (FEM) is established. After numerical code is examined by comparing between numerical and experimental results of the relation of magnetic force-gap, the hysteresis curves of magnetic force-gap including major and minor loops in static case are simulated, and furthermore the dependences of major loop on main parameters including the critical current density and the thickness of superconductor, the residual magnetic field of magnet, and the diameter ratio of superconductor to magnet are studied numerically. In the case of free vibration, by investigating dynamic response of levitated body at different levitation/suspension positions in this magnetic levitation system, we obtain the corresponding results of the variation of magnetic force with gap. All the numerical results of the relation between magnetic force and gap show the strongly nonlinear and highly hysteretic behavior.

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

    PubMed

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

    2015-02-27

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

  17. 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.

  18. Analysis of a hysteresis motor with overexcitation

    SciTech Connect

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

    1982-11-01

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

  19. A power and wavelength detuning-dependent hysteresis loop in a single mode Fabry—Pérot laser diode

    NASA Astrophysics Data System (ADS)

    Wu, Jian-Wei; Bikash, Nakarmi

    2013-08-01

    In this paper, we observe experimentally the optical bistability induced by the side-mode injection power and wavelength detuning in a single mode Fabry—Pérot laser diode (SMFP-LD). Results show that the bistability characteristics of the dominant and injected modes are strongly dependent on the injected input optical power and wavelength detuning in an SMFP-LD. We observe three types of hysteresis loops: counterclockwise, clockwise, and butterfly hysteresis with various loop widths. In the case of a bistability loop caused by injection power, the transition from counterclockwise to clockwise in the hysteresis direction with the wavelength detuning from 0.028 nm to 0.112 nm is observed in a way of butterfly hysteresis for the dominant mode by increasing the wavelength detuning. The width of hysteresis loop, induced by wavelength detuning is also changed while the injection power is enhanced from -7 dBm to -5 dBm.

  20. Size dependent thermal hysteresis in spin crossover nanoparticles reflected within a Monte Carlo based Ising-like model

    NASA Astrophysics Data System (ADS)

    Atitoaie, Alexandru; Tanasa, Radu; Enachescu, Cristian

    2012-04-01

    Spin crossover compounds are photo-magnetic bistable molecular magnets with two states in thermodynamic competition: the diamagnetic low-spin state and paramagnetic high-spin state. The thermal transition between the two states is often accompanied by a wide hysteresis, premise for possible application of these materials as recording media. In this paper we study the influence of the system's size on the thermal hysteresis loops using Monte Carlo simulations based on an Arrhenius dynamics applied for an Ising like model with long- and short-range interactions. We show that using appropriate boundary conditions it is possible to reproduce both the drop of hysteresis width with decreasing particle size, the hysteresis shift towards lower temperatures and the incomplete transition, as in the available experimental data. The case of larger systems composed by several sublattices is equally treated reproducing the shrinkage of the hysteresis loop's width experimentally observed.

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

    NASA Astrophysics Data System (ADS)

    Khoury, Charbel N.

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

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

    SciTech Connect

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

    1988-11-15

    The magnetic stiffness is measured by the torsion pendulum method as a function of the applied field. Measurements are performed on random assemblies of chemically coprecipitated barium ferrite powders. The magnetic stiffness for both minor and major loops of the hysteresis cycle is measured and compared with calculated curves based on the model of coherent rotation. The discrepancies between theory and experiment are partly due to the effect of magnetic interaction.

  3. Ogive Curves

    NSDL National Science Digital Library

    2008-01-01

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

  4. Flexible pivot mount eliminates friction and hysteresis

    NASA Technical Reports Server (NTRS)

    Highman, C. O.

    1970-01-01

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

  5. Circuit increases capability of hysteresis synchronous motor

    NASA Technical Reports Server (NTRS)

    Markowitz, I. N.

    1967-01-01

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

  6. Managing Hysteresis: Three Cornerstones to Fiscal Stability

    ERIC Educational Resources Information Center

    Weeks, Richard

    2012-01-01

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

  7. Hysteresis heating based induction bonding of thermoplastic composites

    Microsoft Academic Search

    W. Suwanwatana; S. Yarlagadda; J GILLESPIEJR

    2006-01-01

    The bonding of polymer matrix composites using magnetic particulate susceptor materials for hysteresis induction heating is investigated in this study. Hysteresis heating is tailored through careful design of the microstructure of magnetic particulate polymer films. The bond strength of hysteresis-welded materials is comparable to that of autoclave-welded materials while offering an order of magnitude reduction in cycle time. The relative

  8. 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.

  9. Hysteresis and anisotropy in ultrathin Fe/Si(001) films

    NASA Astrophysics Data System (ADS)

    Ye, Jun; He, Wei; Wu, Qiong; Hu, Bo; Tang, Jin; Zhang, Xiang-Qun; Chen, Zi-Yu; Cheng, Zhao-Hua

    2014-09-01

    It is challenging to investigate the magnetic anisotropy of Fe/Si(001) film in the case a limited magnetic field strength, when both coherent rotation and domain wall displacement coexist in the magnetization reversal process. Owing to the domain wall displacement, the magnetization reversal switching field is far lower than the magnetic anisotropy field, and, consequently, only the magnetization reversal process near easy axis can be treated as coherent rotation. Here, we record the slope of the magnetic torque curve of an iron film grown on a Si(001) substrate measured near the easy axis by anisotropic magnetoresistance (AMR) to separate the coherent rotation of magnetization reversal process from domain wall displacement. Furthermore, the magnitudes of various magnetic anisotropy constants were derived from the magnetic torque curves. Our work suggests that the AMR at low fields can clearly separate the detailed contributions of various magnetic anisotropies when domain wall displacement existed in Fe(001) ultrathin film. We also report on the hysteresis behavior of such films as measured by magneto-optic Kerr effect.

  10. 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.

  11. Magic Show

    Microsoft Academic Search

    Zachary Brass

    2012-01-01

    With a concentration in theatre, I created a magic show from scratch. Over the course of the semester, I researched both the effects (more commonly known as magic tricks) in a variety of styles, especially mentalism, along with the patter, or script, that is integral in making a good effect into something utterly amazing. I chose a certain set of

  12. The stress dependence of magnetostriction hysteresis in TbDyFe [110] oriented crystal

    NASA Astrophysics Data System (ADS)

    Wang, Zhibin; Liu, Jinghua; Jiang, Chengbao; Xu, Huibin

    2011-06-01

    The magnetostriction curves and minor loops of the TbDyFe [110] oriented crystal are tested under different compressive pre-stress from 0 to 120 MPa. It is observed that the magnetostriction hysteresis first increases from about 33 Oe under 0 MPa, achieves the maximum of about 70 Oe under 30 MPa, and then decreases to about 16 Oe under 120 MPa (near disappearance) with an increase in the compressive pre-stress. By the theoretical simulation, it is found that upon increasing the compressive pre-stress the dominant energy changes from magnetocrystalline anisotropy energy to magnetoelastic energy. This leads to the domain rotation mode changing from irreversibility to reversibility and consequently results in the decrease of magnetostriction hysteresis, which explains the experimental results very well.

  13. The hysteresis phenomenon of the field emission from the graphene film

    NASA Astrophysics Data System (ADS)

    Chen, Jiangtao; Li, Jun; Yang, Juan; Yan, Xingbin; Tay, Beng-Kang; Xue, Qunji

    2011-10-01

    A cycle-testing of field emission behavior was carried out for graphene film prepared by electrophoresis deposition followed by annealing at 700 °C in argon atmosphere. The result shows that the graphene film displays a stable field emission characteristic after a period of conditioning. Also, it is interesting that the field emission hysteresis takes place when the film is measured in loops of rised and falled voltages. The possible physical mechanism of this hysteresis phenomenon may be relevant to the desorption/adsorption effect of gas molecules.

  14. Curved Mirrors

    NSDL National Science Digital Library

    Michael Horton

    2009-05-30

    This inquiry activity will be used before discussing curved mirrors in class. Students will discover how curved mirrors act and how the size and the orientation of the image are related to the distance from the mirror. Ray diagrams for curved mirrors are

  15. Parametric Curves parametric curves (Splines)

    E-print Network

    Treuille, Adrien

    curves (Splines) · polygonal meshes #12;2 Roller coaster · Next programming assignment involves creating a 3D roller coaster animation · We must model the 3D curve describing the roller coaster, but how

  16. Hysteresis and self-sustained oscillations in space charge limited currents

    Microsoft Academic Search

    Yu. N. Gartstein; P. S. Ramesh

    1998-01-01

    A problem of charged particle flow between parallel plate electrodes with arbitrary injection velocities is revisited. A steady-state analysis is advanced by the kinetic simulations which show that the system under consideration can exhibit features characteristic of nonlinear dynamical systems. In particular, a hysteresis between supply limited and space charge limited currents is demonstrated as well as the existence of

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

    Microsoft Academic Search

    Miroslav KrstiC; Hsin-Hsiung Wang

    1997-01-01

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

  18. Hysteresis prediction inside magnetic shields and application.

    PubMed

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

    2014-07-01

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

  19. Hysteresis prediction inside magnetic shields and application

    SciTech Connect

    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.

  20. 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.

  1. Mechanical hysteresis due to microplasticity in alumina with microcracks

    Microsoft Academic Search

    Y. Nishino; H. Ogawa; S. Asano

    1992-01-01

    Stress-strain hysteresis in alumina with microcracks has been investigated by a loading–unloading test in the microstrain range around 10 While there remains a permanent strain after the initial loading, steady-state cyclic loading results in a single closed hysteresis loop with a symmetrical shape. Such a stabilized hysteresis loop is responsible for internal friction and can be attributed to the microplasticity

  2. CPR: curved planar reformation

    Microsoft Academic Search

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

    2002-01-01

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

  3. S-Shaped Discontinuous Shear Thickening Flow Curve in Granular Suspensions

    E-print Network

    Zhongcheng Pan; Henri de Cagny; Bart Weber; Daniel Bonn

    2014-12-17

    We study the rheological behavior of concentrated granular suspensions of simple spherical particles that show discontinuous shear thickening. Under controlled stress, the system exhibits an S-shaped flow curve (stress vs. shear rate) in which the low-viscosity Newtonian regime is connected to the shear thickening regime through a line with negative slope. Under controlled shear rate, a discontinuous transition between the two states is observed. We observe hysteresis in the negative slope section of the flow curve. This hysteresis is sensitive to the rate at which data is taken: by changing the shear rate rapidly, the Newtonian branch can be "overheated" and the shear thickened branch can be "undercooled". Experiments with a novel fluorescent viscosity probe show that the system remains homogeneous if a stress is imposed that is intermediate between the high-and low-viscosity branches, which indicates the continuous formation of a force network due to the frictional forces between particles if the stress is increased towards shear thickening.

  4. Unemployment hysteresis and the NAIRU: a ratchet model

    Microsoft Academic Search

    David J. Smyth; Joshy Z. Easaw

    2001-01-01

    In the 1970s and 1980s the USA and European economies experienced unemployment rates that persistently drifted upwards. The present paper captures this phenomenon by a simple extension of the hysteresis approach to the natural rate hypothesis of unemployment using a ratchet model. The impact of peak unemployment levels on unemployment hysteresis is incorporated using a traditional ratchet model. The model

  5. Low-Voltage CMOS Comparators With Programmable Hysteresis

    E-print Network

    Furth, Paul

    ............................................................28 3.2.2 High-swing cascode current source.....................................29 3.2.3 OperationLow-Voltage CMOS Comparators With Programmable Hysteresis BY VISHNU B. KULKARNI Master of Science of comparators with programmable hysteresis. Optimizations are done in order to obtain minimum DC offsets

  6. A Domain Wall Model for Hysteresis in Piezoelectric Materials

    E-print Network

    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

  7. Discharge mode transition and hysteresis in inductively coupled plasma

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  8. Thermal hysteresis behaviors of thermoelectric properties

    NASA Astrophysics Data System (ADS)

    Iwasaki, Hideo

    2014-12-01

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

  9. 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.

  10. Ultra-precise tracking control of piezoelectric actuators via a fuzzy hysteresis model.

    PubMed

    Li, Pengzhi; Yan, Feng; Ge, Chuan; Zhang, Mingchao

    2012-08-01

    In this paper, a novel Takagi-Sugeno (T-S) fuzzy system based model is proposed for hysteresis in piezoelectric actuators. The antecedent and consequent structures of the fuzzy hysteresis model (FHM) can be, respectively, identified on-line through uniform partition approach and recursive least squares (RLS) algorithm. With respect to controller design, the inverse of FHM is used to develop a feedforward controller to cancel out the hysteresis effect. Then a hybrid controller is designed for high-performance tracking. It combines the feedforward controller with a proportional integral differential (PID) controller favourable for stabilization and disturbance compensation. To achieve nanometer-scale tracking precision, the enhanced adaptive hybrid controller is further developed. It uses real-time input and output data to update FHM, thus changing the feedforward controller to suit the on-site hysteresis character of the piezoelectric actuator. Finally, as to 3 cases of 50 Hz sinusoidal, multiple frequency sinusoidal and 50 Hz triangular trajectories tracking, experimental results demonstrate the efficiency of the proposed controllers. Especially, being only 0.35% of the maximum desired displacement, the maximum error of 50 Hz sinusoidal tracking is greatly reduced to 5.8 nm, which clearly shows the ultra-precise nanometer-scale tracking performance of the developed adaptive hybrid controller. PMID:22938339

  11. Ultra-precise tracking control of piezoelectric actuators via a fuzzy hysteresis model

    NASA Astrophysics Data System (ADS)

    Li, Pengzhi; Yan, Feng; Ge, Chuan; Zhang, Mingchao

    2012-08-01

    In this paper, a novel Takagi-Sugeno (T-S) fuzzy system based model is proposed for hysteresis in piezoelectric actuators. The antecedent and consequent structures of the fuzzy hysteresis model (FHM) can be, respectively, identified on-line through uniform partition approach and recursive least squares (RLS) algorithm. With respect to controller design, the inverse of FHM is used to develop a feedforward controller to cancel out the hysteresis effect. Then a hybrid controller is designed for high-performance tracking. It combines the feedforward controller with a proportional integral differential (PID) controller favourable for stabilization and disturbance compensation. To achieve nanometer-scale tracking precision, the enhanced adaptive hybrid controller is further developed. It uses real-time input and output data to update FHM, thus changing the feedforward controller to suit the on-site hysteresis character of the piezoelectric actuator. Finally, as to 3 cases of 50 Hz sinusoidal, multiple frequency sinusoidal and 50 Hz triangular trajectories tracking, experimental results demonstrate the efficiency of the proposed controllers. Especially, being only 0.35% of the maximum desired displacement, the maximum error of 50 Hz sinusoidal tracking is greatly reduced to 5.8 nm, which clearly shows the ultra-precise nanometer-scale tracking performance of the developed adaptive hybrid controller.

  12. Light Curves

    NSDL National Science Digital Library

    2013-02-12

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

  13. Hysteresis and precession of a swirling jet normal to a wall.

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    PubMed Central

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

    2015-01-01

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

  16. Central Rotation Curves of Galaxies

    E-print Network

    Yoshiaki SOFUE

    2000-10-30

    We emphasize the use of high-resolution CO line observations to derive central rotation curves of galaxies. We present an example for high-resolution interferometer observations of NGC 3079, and discuss the PV diagram and derived rotation curve. The CO central rotation curves are combined with the outer curves from \\ha and HI-line observations to obtain total RC. We show that well resolved RCs for massive galaxies generally start from non-zero velocities at the nucleus.

  17. HYSTERESIS OF BACKFLOW IMPRINTED IN COLLIMATED JETS

    SciTech Connect

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

    2010-01-20

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

  18. Hysteresis and nonlinear elasticity in rocks

    SciTech Connect

    McCall, K.R.; Guyer, R.A.

    1993-12-01

    The purpose of this paper is to describe a theory of the propagation of elastic waves in hysteretic nonlinear elastic materials, e.g., rock. In the next section, we introduce the Priesach-Mayergoyz (P-M) model [6,7] of hysteretic systems and adapt it to describe the hysteretic mesoscopic elastic units (HMEU) determining the elastic properties of a rock. We combine the P-M model with effective medium theory (EMT) [8] to find the elastic response of a rock that has experienced a specified pressure history. Next, we consider elastic wave propagation in a hysteretic nonlinear elastic system governed by a history dependent equation of state. We consider one-dimensional propagation of compressional waves. The equation of motion for the longitudinal displacement field contains the same hysteretic nonlinear interactions that characterize the equation of state. We solve the equation of motion using the Green function technique developed by McCall [9]. This solution lets us identify the qualitative features in harmonic generation that are signatures of nonlinearity and hysteresis.

  19. High hysteresis in a homogeneous metallic glass

    NASA Astrophysics Data System (ADS)

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

    2003-05-01

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

  20. Hysteresis and transition in swirling nonpremixed flames

    SciTech Connect

    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)

  1. Hysteresis mechanism and control in pentacene organic field-effect transistors with polymer dielectric

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Shi, Wei; Han, Shijiao; Yu, Junsheng

    2013-05-01

    Hysteresis mechanism of pentacene organic field-effect transistors (OFETs) with polyvinyl alcohol (PVA) and/or polymethyl methacrylate (PMMA) dielectrics is studied. Through analyzing the electrical characteristics of OFETs with various PVA/PMMA arrangements, it shows that charge, which is trapped in PVA bulk and at the interface of pentacene/PVA, is one of the origins of hysteresis. The results also show that memory window is proportional to both trap amount in PVA and charge density at the gate/PVA or PVA/pentacene interfaces. Hence, the controllable memory window of around 0 ˜ 10 V can be realized by controlling the thickness and combination of triple-layer polymer dielectrics.

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

    E-print Network

    ’t Mannetje, D. J. C. M.

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

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

    E-print Network

    Bayless, Jacob D. (Jacob Daniel)

    2014-01-01

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

  4. On the question of hysteresis in Hall magnetohydrodynamic reconnection

    SciTech Connect

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

    2010-11-15

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

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

    E-print Network

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

    2014-01-01

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

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

    E-print Network

    Loureiro, Andre Oliveira Ferreira

    2013-07-03

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

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

    E-print Network

    Smyth, Katherine M.

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

  8. Could linear hysteresis contribute to shear wave losses in tissues?

    PubMed

    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

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

    E-print Network

    Boyer, Edmond

    Cavitation level-acoustic intensity hysteresis: experimental and numerical characterization P cours Albert Thomas 69424 Lyon cedex 03 pauline.labelle@inserm.fr Proceedings of the Acoustics 2012 importance. When applying successive ultrasonic shots for increasing acoustic intensities, the inertial

  10. Approximation properties of a PWL circuit model of hysteresis

    NASA Astrophysics Data System (ADS)

    Cincotti, Silvano

    2000-01-01

    In this paper, some identification methods for a piece wise linear (PWL) circuit model of hysteresis phenomenon are presented and compared. The model provides a close prediction of static hysteresis and exhibits realistic dynamic features. The parameter identification problem can be solved by means of a suitable procedures based on representation theorem, on optimisation methods and on neural networks. Basic features are addressed and discussed.

  11. 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.

  12. Curved Knives

    Microsoft Academic Search

    W. F. Sinclair

    1897-01-01

    IT may interest your correspondent, Dr. Otis T. Mason, to know that the curved ``drawing-knife'' described by him has representatives in Western (British) India. The Kolis (fishing races) of the Bombay coast wore lately, and some still wear, knives made by local blacksmiths, of which the blade, 2 to 3 inches long, was shaped and edged like that of an

  13. Magnetic hysteresis of an artificial square ice studied by in-plane Bragg x-ray resonant magnetic scattering

    NASA Astrophysics Data System (ADS)

    Morgan, J. P.; Kinane, C. J.; Charlton, T. R.; Stein, A.; Sánchez-Hanke, C.; Arena, D. A.; Langridge, S.; Marrows, C. H.

    2012-06-01

    We report X-ray resonant magnetic scattering studies of a Permalloy artificial square ice nanomagnet array, focussing on the field-driven evolution of the sum ? and difference ? signals of left and right handed circularly polarized synchrotron X-rays at different lateral positions in reciprocal space Qx. We used X-rays tuned to the Fe L3 resonance energy, with the scattering plane aligned along a principal symmetry axis of the array. Details of the specular ? hysteresis curve are discussed, following the system magnetization from an initial demagnetized state. The periodic structure gives rise to distinct peaks at in-plane reciprocal Bragg positions, as shown by fitting ?(Qx) to a model based on a simple unit cell structure. Diffraction order-dependent hysteresis in ? is observed, indicative of the reordering of magnetization on the system's two interpenetrating sublattices, which markedly deviates from an ideal Ising picture under strong applied fields.

  14. An undulation theory for condensation in open end slit pores: critical hysteresis temperature & critical hysteresis pore size.

    PubMed

    Fan, Chunyan; Zeng, Yonghong; Do, D D; Nicholson, D

    2014-06-28

    A new theory of condensation in an open end slit pore, based on the concept of temperature dependent undulation, at the interface separating the adsorbed phase and the gas-like region, is presented. The theory, describes, for the first time, the microscopic origin of the critical hysteresis temperature and the critical hysteresis pore size, properties which are not accessible to any classical theories. PMID:24826906

  15. Comparison of growth curve parameters of organs and body components in meat- (Coturnix coturnix coturnix) and laying-type (Coturnix coturnix japonica) quail show interactions between gender and genotype.

    PubMed

    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

    2015-02-01

    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. 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. 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. Females had greater growth potential in breast, wings and back than males for both yellow and red laying quail. PMID:25490970

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

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2008-01-01

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

  18. Hysteresis from antiferromagnet domain-wall processes in exchange-biased systems: Magnetic defects and thermal effects

    Microsoft Academic Search

    Joo-Von Kim; R. L. Stamps

    2005-01-01

    The partial domain-wall theory of exchange bias predicts bias field magnitudes and film thickness dependencies consistent with certain experimental systems. However, the theory does not account for the coercivity enhancement that accompanies the hysteresis loop shift in single domain materials. We show theoretically that the presence of an attractive domain-wall potential in the antiferromagnet, arising from magnetic impurities, for example,

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

    NASA Astrophysics Data System (ADS)

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

    2008-07-01

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

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

    USGS Publications Warehouse

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  2. Curved Space or Curved Vacuum?

    E-print Network

    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.

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

    SciTech Connect

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

    2009-01-15

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

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

    NASA Technical Reports Server (NTRS)

    Bachmann, Kurt T.; White, Oran R.

    1994-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  6. 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.

  7. 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.

  8. Saturation overshoot and hysteresis for twophase flow in porous media

    NASA Astrophysics Data System (ADS)

    Hilfer, R.; Steinle, R.

    2014-10-01

    Saturation overshoot and hysteresis for two phase flow in porous media are briefly reviewed. Old and new challenges are discussed. It is widely accepted that the traditional Richards model for twophase flow in porous media does not support non-monotone travelling wave solutions for the saturation profile. As a concequence various extensions and generalizations have been recently discussed. The review highlights different limits within the traditional theory. It emphasizes the relevance of hysteresis in the Buckley-Leverett limit with jump-type hysteresis in the relative permeabilities. Reviewing the situation it emerges that the traditional theory may have been abandoned prematurely because of its inability to predict saturation overshoot in the Richards limit.

  9. 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.

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

    USGS Publications Warehouse

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

    2013-01-01

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

  11. Interaction of bipolaron with the H2O/O2 redox couple causes current hysteresis in organic thin-film transistors.

    PubMed

    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

  12. Interaction of bipolaron with the H2O/O2 redox couple causes current hysteresis in organic thin-film transistors

    NASA Astrophysics Data System (ADS)

    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.

  13. The frequency-dependent Jiles-Atherton hysteresis model

    NASA Astrophysics Data System (ADS)

    Malczyk, Robert; Izydorczyk, Jacek

    2015-04-01

    An extension of the Jiles-Atherton (J-A) magnetic hysteresis model is proposed in the paper. The physical J-A model has been substituted with the specially chosen mathematical Chua model. The proposed model produces identical results to those of the original J-A model for the static magnetic hysteresis loop. The new model permits the inclusion of a wide variety of additional effects observed for ferromagnetic materials without invalidating the well-known and broadly used J-A model parameters. Thus, it is possible to effectively model phenomena, whose detailed physical model would require complex mathematical calculations.

  14. Dielectric Hysteresis Loop in Alicyclic and Aromatic Polyamides

    NASA Astrophysics Data System (ADS)

    Murata, Yukinobu; Tsunashima, Kenji; Koizumi, Naokazu

    1994-03-01

    The relationship between electric displacement D and electric field E was studied for alicyclic polyamides of 1,3-bis(aminomethyl)cyclohexane and adipic, pimelic and sebacic acids, an aromatic polyamide prepared from hexamethylenediamine (HMD) and isophthalic acid and a copolyamide of HMD with isophthalic and terephthalic acids. Quenched samples of these polyamides were poorly crystalline or amorphous and exhibited a D-E hysteresis loop with the remanent polarization of 26 to 38 mC·m-2. The remanent polarizations disappeared at the glass transition temperature of each sample. The origin of the D-E hysteresis loop is attributable to amide groups in amorphous regions.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

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

    SciTech Connect

    Morozovska, Anna N.; Morozovsky, Nicholas V. [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.

  17. Properties of ferromagnetic film hysteresis, on the surface of a hard-magnetic antiferromagnet, with a domain structure

    NASA Astrophysics Data System (ADS)

    Kovalev, A. S.; Pankratova, M. L.

    2014-11-01

    This is a theoretical investigation of the exchange bias phenomenon, and the properties of a thin magnetic film's magnetization hysteresis loop, on the rough surface of a hard-magnetic antiferromagnet. An interface model with a periodic structure of atomic steps is presented. These atomic steps are associated with a spatially inhomogeneous distribution of the ferromagnetic film magnetization, akin to a system of domain walls. This structure leads to a complicated external field dependence of magnetization: the hysteresis curve can assume an asymmetrical shape and "fall apart" into two hysteresis loops, divided by a "horizontal plateau," or an area with constant field-independent magnetization. Such field dependence behavior has been recently observed experimentally in different ferro/antiferromagnet systems. The field dependence of magnetization has been obtained analytically using the long-wave approximation for various characteristics of ferromagnetic film (its thickness, values of exchange interaction, and magnetic anisotropy), and the interface (the period of the inhomogeneous structure, and exchange interaction through the interface). The analytical results are confirmed by numerical calculations for the corresponding discrete model with a more complex interface structure.

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

    E-print Network

    Smyth, Katherine Marie

    2010-01-01

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

  19. Causes and implications of colloid and microorganism retention hysteresis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Experiments were designed to better understand the causes and implications of colloid and microorganism retention hysteresis with transients in solution ionic strength (IS). Saturated packed column experiments were conducted using two sizes of carboxyl modified latex (CML) microspheres (0.1 and 1.1...

  20. 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.

  1. Idealized Hysteresis Modeling of Electrorheological and Magnetorheological Dampers

    Microsoft Academic Search

    Norman M. Wereley; Li Pang; Gopalakrishna M. Kamath

    1998-01-01

    The hysteresis behavior of a linear stroke magnetorheological damper is characterized for sinusoidal displacement excitation at 2.0 Hz (nominal). Four different modeling perspectives are discussed for purposes of system identification procedures, including: (1) equivalent viscous damping, (2) nonlinear Bingham plastic model, (3) nonlinear biviscous model, and (4) nonlinear hysteretic biviscous model. By progressively adding model parameters with which to better

  2. Modeling of a Magnetorheological Actuator Including Magnetic Hysteresis

    Microsoft Academic Search

    Jinung An; Dong-Soo Kwon

    2003-01-01

    Magnetorheological (MR) actuators provide controlled torque through control of an applied magnetic field. Therefore knowledge of the relationship between the applied current and output torque is required. This paper presents a new nonlinear modeling of MR actuators considering magnetic hysteresis to determine the torque-current nonlinear relationship. Equations for transmitted torque are derived according to mechanical shear configurations of the MR

  3. Hysteresis heating based induction bonding of composite materials

    Microsoft Academic Search

    Witchuda Suwanwatana

    2004-01-01

    The viability of using magnetic particulate susceptor materials for induction heating during bonding of polymer matrix composites is well established in this work. The unique ability to offer localized heating, geometric flexibility, and self-controlled temperature is the major advantage of this technique. Hysteresis heating is tailored through careful design of the microstructure of nickel particulate polymer films (Ni\\/PSU). An excellent

  4. Similarity Hypothesis for Capillary Hysteresis in Porous Materials

    Microsoft Academic Search

    J. R. Philip

    1964-01-01

    A quantitative description of the capillary hysteresis properties of a porous ma- terial is developed through bivariate distribution density function f(a, ), where a andare wetting and drying potentials. This is formally equivalent to the independent domain theory of Poulovassilis. The similarity hypothesis ' (implying, loosely, that the distribution of geometrical relationships between wetting and drying meniscus curvatures is independent

  5. Hysteresis during lithium insertion in hydrogen-containing carbons

    Microsoft Academic Search

    Tao Zheng; J. R. Dahn; W. R. McKinnon

    1996-01-01

    The authors studied lithium insertion in hydrogen-containing carbons heated at temperatures near 700 C. High capacities with large hysteresis (lithium insertion into these carbons at nearly 0 V and removal at nearly 1 V) were shown to be proportional to the hydrogen content of the samples. It is believed that the lithium atoms may bind on hydrogen-terminated edges of hexagonal

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

    PubMed

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

    2011-08-16

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

  7. A Domain Wall Model for Hysteresis in Ferroelastic Materials

    E-print Network

    with experimental stress-strain data. Keywords: Ferroelastic hysteresis; shape memory alloy; domain wall theory; ferroelastic domain; superelasticity; Landau theory of phase transitions;anyhysteretic strain; domain wall the model in two steps. First, we use the Landau theory of phase transitions to characterize the effective

  8. A Domain Wall Model for Hysteresis in Ferroelastic Materials

    E-print Network

    with experimental stress­strain data. Keywords: Ferroelastic hysteresis; shape memory alloy; domain wall theory; ferroelastic domain; superelasticity; Landau theory of phase transitions;anyhysteretic strain; domain wall the model in two steps. First, we use the Landau theory of phase transitions to characterize the e

  9. Rainflow Counting and Energy Dissipation for Hysteresis Models in Elastoplasticity

    E-print Network

    Krejcí, Pavel

    Rainflow Counting and Energy Dissipation for Hysteresis Models in Elastoplasticity Martin Brokate Republic Abstract The rainflow counting method is widely used in the context of fatigue analy- sis for some remarks, we exclusively deal with the uniaxial case. Running title. Rainflow Counting and Energy

  10. Hysteresis and reluctance electric machines with bulk HTS rotor elements

    Microsoft Academic Search

    L. K. Kovalev; K. V. Ilushin; S. M.-A. Koneev; K. L. Kovalev; V. T. Penkin; V. N. Poltavets; W. Gawalek; T. Habisreuther; B. Oswald; K.-J. Best

    1999-01-01

    Two new types of HTS electric machines are considered. The first type is hysteresis motors and generators with cylindrical and disk rotors containing bulk HTS elements. The second type is reluctance motors with compound HTS-ferromagnetic rotors. The compound HTS-ferromagnetic rotors, consisting of joined alternating bulk HTS (YBCO) and ferromagnetic (iron) plates, provide a new active material for electromechanical purposes. Such

  11. Hysteresis electrical motors with bulk melt-textured YBCO

    Microsoft Academic Search

    L. K. Kovalev; K. V. Ilushin; V. T. Penkin; K. L. Kovalev; V. S. Semenikhin; V. N. Poltavets; A. E. Larionoff; W. Gawalek; T. Habisreuther; T. Strasser; A. K. Shikov; E. G. Kazakov; V. V. Alexandrov

    1998-01-01

    New types of electrical motors based on bulk high temperature superconductors (HTS) are presented. Theoretical and experimental research of these motors is described. Results for a series of 100, 300, 500 and 1000 W HTS motors with cylindrical and disk rotors are presented. It is shown that, at liquid nitrogen temperatures, the specific mass-dimension parameter of hysteresis HTS machines is

  12. Friction and Adhesion Hysteresis between Surfactant Monolayers in Water

    E-print Network

    Klein, Jacob

    Friction and Adhesion Hysteresis between Surfactant Monolayers in Water Wuge H. Briscoe Physical with a double-chained quaternary ammonium surfactant in intimate adhesive contact in water. This enables us to propose a mechanism for surfactant boundary lubrication in water that is rather different from the classic

  13. A novel SVM-based hysteresis current controller

    Microsoft Academic Search

    Bong-Hwan Kwon; Tae-Woo Kim; Jang-Hyoun Youm

    1998-01-01

    In this paper, a novel space vector modulation (SVM)-based hysteresis current controller (HCC) for squirrel cage induction motors is proposed. This technique utilizes all advantages of the HCC and SVM technique. The controller determines a set of space vectors from a region detector and applies a space vector selected according to the main HCC. A set of space vectors including

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

    SciTech Connect

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

    2006-07-15

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

  15. Curves and Their Properties.

    ERIC Educational Resources Information Center

    Yates, Robert C.

    This volume, a reprinting of a classic first published in 1952, presents detailed discussions of 26 curves or families of curves, and 17 analytic systems of curves. For each curve the author provides a historical note, a sketch or sketches, a description of the curve, a discussion of pertinent facts, and a bibliography. Depending upon the curve,…

  16. Adsorption/desorption hysteresis in the adsorption isotherms for Kr and Xe on exfoliated graphite

    NASA Astrophysics Data System (ADS)

    Kosugi, T.; Usui, Y.; Arakawa, I.

    1993-05-01

    The adsorption/desorption hysteresis which appears in the adsorption isotherm for Kr physisorbed on exfoliated graphite has a very characteristic feature. A sharp transition at the termination of the hysteresis in the desorption branch of the isotherm suggests a first-order phase transition. The temperature dependence of the hysteresis for Kr and Xe on exfoliated graphite was investigated. The origin of the hysteresis of Kr is thought to be capillary condensation accompanied by a liquid-solid phase transition.

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

    PubMed

    Poltoratski, Sonia; Tong, Frank

    2014-10-01

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

  18. Partial and full inverse compensation for hysteresis in smart material systems

    Microsoft Academic Search

    Ralph C. Smith; C. Bouron; Rick Zrostlik

    2000-01-01

    Smart material transducers employing piezoceramic or magnetostrictive drive components typically exhibit constitutive nonlinearities and hysteresis at moderate to high drive levels. In this paper, we discuss two techniques to compensate for hysteresis in high performance transducers. The first is based on a complete transducer model, and the resulting compensator accommodates both the constitutive nonlinearities and hysteresis inherent to the smart

  19. Finite element analysis of hysteresis motor using the vector magnetization-dependent model

    Microsoft Academic Search

    Hong-Kyu Kim; Hyun-Kyo Jung; Sun-Ki Hong

    1998-01-01

    This paper presents a finite element analysis procedure combined with a vector hysteresis model for the accurate analysis of an hysteresis motor. The vector magnetization-dependent model is adopted to calculate the vector magnetization of the hysteresis ring. From the magnitude and direction of the magnetic field intensity, the magnetization of each ring element is calculated by the vector model. By

  20. Adaptive variable structure control of a class of nonlinear systems with unknown Prandtl-Ishlinskii hysteresis

    Microsoft Academic Search

    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

  1. 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.

  2. Mesoscopic resistive switch: non-volatility, hysteresis and negative differential resistance

    NASA Astrophysics Data System (ADS)

    Savel'ev, Sergey E.; Marchesoni, Fabio; Bratkovsky, Alexander M.

    2013-12-01

    We show how a simple model nanoswitch can perform as a memory resistor. Its resistance is determined by electron tunneling through a nanoparticle diffusing around one or more potential minima located between the electrodes in the presence of Joule's heat dissipation. In the case of a single potential minimum, we observe hysteresis of the resistance at finite applied currents and negative differential resistance. For two (or more) minima the switching mechanism is non-volatile, meaning that the memristor can switch to a resistive state of choice and stay there. Moreover, the noise spectra of the switch exhibit 1/ f 2 ? 1/ f crossover, in agreement with recent experimental results.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Zheng, Jiashan; Wang, Yifu

    2014-05-01

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

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

    USGS Publications Warehouse

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

    2007-01-01

    River suspended-sediment concentrations provide insights to the erosion and transport of materials from a landscape, and changes in concentrations with time may result from landscape processes or human disturbance. Here we show that suspended-sediment concentrations in the Santa Ana River, California, decreased 20-fold with respect to discharge during a 34-year period (1968?2001). These decreases cannot be attributed to changes in sampling technique or timing, nor to event or seasonal hysteresis. Annual peak and total discharge, however, reveal sixfold increases over the 34-year record, which largely explain the decreases in sediment concentration by a nonlinear dilution process. The hydrological changes were related to the widespread urbanization of the watershed, which resulted in increases in storm water discharge without detectable alteration of sediment discharge, thus reducing suspended-sediment concentrations. Periodic upland wildfire significantly increased water discharge, sediment discharge, and suspended-sediment concentrations and thus further altered the rating curve with time. Our results suggest that previous inventories of southern California sediment flux, which assume time-constant rating curves and extend these curves beyond the sampling history, may have substantially overestimated loads during the most recent decades.

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

    PubMed

    Huang, Tao; Duman, John G

    2002-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Landers, Mark N.; Sturm, Terry W.

    2013-09-01

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

  8. Hysteresis effects in the formation of a neutralizing beam plasma at low ion energy

    NASA Astrophysics Data System (ADS)

    Rafalskyi, Dmytro; Aanesland, Ane

    2013-11-01

    In this paper, the PEGASES II thruster prototype is used as an ion source generating low-energy (<300\\ \\text{eV}) positive Ar ion beam, extracted without an external neutralizer. The ions are extracted and accelerated from the source using a two-grid system. The extracted positive ion beam current is measured on a large beam target that can be translated along the acceleration axis. The ion beam current shows a stepwise transition from a low-current to a high-current extraction regime with hysteresis. The hysteresis region depends strongly upon the beam target position. Langmuir probe measurements in the plume show high plasma potentials and low plasma densities in the low-current mode, while the plasma potential drops and the density increases in the high-current mode. The ion energy distribution functions of the beam are measured for different regimes of ion extraction. The ion beam extracted in the high-current mode is indicated by the presence of an additional low-energy peak corresponding to ions from an ion-beam plasma created in the downstream chamber, as well as 10-20 times higher intensity of the primary ion beam peak. The hysteresis behavior is explained by the formation of a downstream neutralizing beam plasma, that depends on the target position and pressure in agreement with a Paschen-like breakdown by secondary electrons. The obtained results are of high relevance for further development of the PEGASES thruster, as well as for improving existing neutralizer-free concepts of the broad-beam ion sources.

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

    USGS Publications Warehouse

    Landers, Mark N.; Sturm, Terry W.

    2013-01-01

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

  10. Charge state hysteresis in semiconductor quantum dots

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  11. Archimedes Curves

    ERIC Educational Resources Information Center

    Swain, Gordon A.

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  13. Hysteresis and Kinetic Effects During Liquid-Solid Transitions

    SciTech Connect

    Streitz, F H; Chau, R

    2009-02-17

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

  14. Magnetic hysteresis in granular CuCo alloys

    NASA Astrophysics Data System (ADS)

    Allia, P.; Coisson, M.; Tiberto, P.; Vinai, F.; Knobel, M.

    1999-04-01

    Room-temperature hysteresis loops of granular Cu100-xCox alloys (5?x?15) obtained by planar flow casting in air and submitted to proper annealing treatments have been measured up to a field of 10 kOe by means of a vibrating sample magnetometer. In major loops (|Hvert|=10 kOe), the reduced remanence-to-saturation ratio mr=Mr/Ms and the coercivity Hc measured on all studied materials appear to be related by an almost linear law of the type mr?1/3 (?Hc/kT), ? being the average magnetic moment on Co particles. A similar relation is also observed on minor symmetrical loops (100 Oe?|Hvert|?9 kOe). The observed results are accounted for by a model which considers the hysteresis as originating by magnetic interactions among nearly superparamagnetic Co particles.

  15. Efficiency of Hysteresis Rods in Small Spacecraft Attitude Stabilization

    PubMed Central

    Farrahi, Assal; Sanz-Andrés, Ángel

    2013-01-01

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

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

    PubMed

    Gu, Yu; Kornev, Konstantin G

    2014-04-28

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

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

    SciTech Connect

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

    1992-01-01

    The objective is to investigate experimentally and theoretically the effects of neutron embrittlement and biaxial stress on magnetic properties in steels, using various magnetic measurement techniques. Interaction between experiment and modeling should suggest efficient magnetic measurement procedures for determining neutron embrittlement biaxial stress. This should ultimately assist in safety monitoring of nuclear power plants and of gas and oil pipelines. In the first six months of this first year study, magnetic measurements were made on steel surveillance specimens from the Indian Point 2 and D.C. Cook 2 reactors. The specimens previously had been characterized by Charpy tests after specified neutron fluences. Measurements now included: (1) hysteresis loop measurement of coercive force, permeability and remanence, (2) Barkhausen noise amplitude; and (3) higher order nonlinear harmonic analysis of a 1 Hz magnetic excitation. Very good correlation of magnetic parameters with fluence and embrittlement was found for specimens from the Indian Point 2 reactor. The D.C. Cook 2 specimens, however showed poor correlation. Possible contributing factors to this are: (1) metallurgical differences between D.C. Cook 2 and Indian Point 2 specimens; (2) statistical variations in embrittlement parameters for individual samples away from the stated men values; and (3) conversion of the D.C. Cook 2 reactor to a low leakage core configuration in the middle of the period of surveillance. Modeling using a magnetomechanical hysteresis model has begun. The modeling will first focus on why Barkhausen noise and nonlinear harmonic amplitudes appear to be better indicators of embrittlement than the hysteresis loop parameters.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    Magnetic properties are sensitive proxies to characterize FeNi metal phases in meteorites. We present a data set of magnetic hysteresis properties of 91 ordinary chondrite falls. We show that hysteresis properties are distinctive of individual meteorites while homogeneous among meteorite subsamples. Except for the most primitive chondrites, these properties can be explained by a mixture of multidomain kamacite that dominates the induced magnetism and tetrataenite (both in the cloudy zone as single-domain grains, and as larger multidomain grains in plessite and in the rim of zoned taenite) dominates the remanent magnetism, in agreement with previous microscopic magnetic observations. The bulk metal contents derived from magnetic measurements are in agreement with those estimated previously from chemical analyses. We evidence a decreasing metal content with increasing petrologic type in ordinary chondrites, compatible with oxidation of metal during thermal metamorphism. Types 5 and 6 ordinary chondrites have higher tetrataenite content than type 4 chondrites. This is compatible with lower cooling rates in the 650-450 °C interval for higher petrographic types (consistent with an onion-shell model), but is more likely the result of the oxidation of ordinary chondrites with increasing metamorphism. In equilibrated chondrites, shock-related transient heating events above approximately 500 °C result in the disordering of tetrataenite and associated drastic change in magnetic properties. As a good indicator of the amount of tetrataenite, hysteresis properties are a very sensitive proxy of the thermal history of ordinary chondrites, revealing low cooling rates during thermal metamorphism and high cooling rates (e.g., following shock reheating or excavation after thermal metamorphism). Our data strengthen the view that the poor magnetic recording properties of multidomain kamacite and the secondary origin of tetrataenite make equilibrated ordinary chondrites challenging targets for paleomagnetic study.

  19. Degradation and capacitance: voltage hysteresis in CdTe devices

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

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

  20. Hysteresis of primary cosmic rays associated with Forbush decreases

    Microsoft Academic Search

    R. S. Rajan

    1976-01-01

    A variation of quasi-steady primary-cosmic-ray intensities during Forbush events is reported which was detected in data obtained by a neutron monitor, the OGO 1 and 3 ion chambers, and daily observations of upper-atmosphere intensities recorded with standardized Geiger-Mueller counters. A regression plot of the intensities of high- and low-rigidity primaries is found to exhibit hysteresis loops during Forbush decreases, indicating

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

    SciTech Connect

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

    2014-02-18

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

  2. Proton intercalation hysteresis in charging and discharging nickel hydroxide electrodes

    Microsoft Academic Search

    Kathryn Podolske Ta; J. Newman

    1999-01-01

    A reproducible hysteresis in charge-discharge cycling of thin-film (10--40 nm thickness) electroprecipitated nickel hydroxide electrodes was quantified. Thin-film electrodes were prepared both with and without coprecipitated cobalt hydroxide, a common additive to nickel hydroxide electrodes. The ascending and descending branches of the hysteretic loop were determined. Experimental data were gathered using commonly employed techniques to capture electrode behavior on short-

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

    SciTech Connect

    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.}

  4. Tuning size and thermal hysteresis in bistable spin crossover nanoparticles.

    PubMed

    Galán-Mascarós, José Ramón; Coronado, Eugenio; Forment-Aliaga, Alicia; Monrabal-Capilla, María; Pinilla-Cienfuegos, Elena; Ceolin, Marcelo

    2010-06-21

    Nanoparticles of iron(II) triazole salts have been prepared from water-organic microemulsions. The mean size of the nanoparticles can be tuned down to 6 nm in diameter, with a narrow size distribution. A sharp spin transition from the low spin (LS) to the high spin (HS) state is observed above room temperature, with a 30-40-K-wide thermal hysteresis. The same preparation can yield second generation nanoparticles containing molecular alloys by mixing triazole with triazole derivatives, or from metallic mixtures of iron(II) and zinc(II). In these nanoparticles of 10-15 nm, the spin transition "moves" towards lower temperatures, reaching a 316 K limit for the cooling down transition and maintaining a thermal hysteresis over 15-20-K-wide. The nanoparticles were characterized by dynamic light scattering, TEM, and AFM, after deposition on gold or silicon surfaces. The spin transition was characterized by magnetic susceptibility measurements and EXAFS (in solid samples after solvent removal) and also by the color change between the LS (violet) and HS (colorless) states in an organic solvent suspension. The discovery of bistable magnetic nanoparticles of 6 nm with a wide thermal hysteresis above room temperature showcases the actual possibilities of spin crossover materials for nanotechnological applications. PMID:20503990

  5. Using stormwater hysteresis to characterize karst spring discharge.

    PubMed

    Toran, Laura; Reisch, Chad E

    2013-01-01

    Discharge from karst springs contains a mixture of conduit and matrix water, but the variations in groundwater mixing are poorly known. Storm events present an opportunity to try to map flow components because water entering during storms is more dilute and provides a tracer as it mixes with pre-event water along the flowpath from the recharge area to discharge at a spring. We used hysteresis plots of Mg/Ca ratios in a spring in the Cumberland Valley of Pennsylvania to map conduit (higher Ca) vs. diffuse (higher Mg) sources of recharge. We observed two types of temporal heterogeneity: within a storm event and from storm to storm. The timing of the variation in Mg/Ca suggested sources of mixing waters. An increase in the Mg/Ca ratio at the beginning of some storms while conductivity declined suggested diffuse recharge through the epikarst. The rapid changes in Mg/Ca ratios for low-intensity events probably occurred as the rainfall waxed and waned and illustrate that a variety of flowpaths are available at this spring because additional flushing of Mg occurred. In contrast, the conductivity hysteresis began with dilute water initially and rotation was similar from storm to storm. Hysteresis plots of the Mg/Ca ratio have the potential of revealing more of the complexity in discharge than conductivity alone. A better understanding of flow components in karst is needed to protect these aquifers as a groundwater resource. PMID:22974348

  6. Proton intercalation hysteresis in charging and discharging nickel hydroxide electrodes

    SciTech Connect

    Ta, K.P.; Newman, J.

    1999-08-01

    A reproducible hysteresis in charge-discharge cycling of thin-film (10--40 nm thickness) electroprecipitated nickel hydroxide electrodes was quantified. Thin-film electrodes were prepared both with and without coprecipitated cobalt hydroxide, a common additive to nickel hydroxide electrodes. The ascending and descending branches of the hysteretic loop were determined. Experimental data were gathered using commonly employed techniques to capture electrode behavior on short- and long-time scales. Cyclic voltammetry and galvanostatic discharge experiments were performed, and a macroscopic model of the nickel hydroxide solid material was constructed and used to interpret the simultaneous mass-transfer, kinetic, and thermodynamic phenomena occurring at the nickel hydroxide intercalation electrode. The persistent hysteresis exhibited by these thin-film electrodes cannot be due only to solid-state mass-transfer limitations. Agreement between calculated and experimental results is achieved with treatment of the hysteresis effect as a permanent, thermodynamic quantity. The numerical model may be applied to most rechargeable cells and is especially suited for systems which exhibit a permanent hysteretic loop or in which side reactions are prevalent. Model results agree with current and potential waveforms gathered from experiments performed with nickel hydroxide thin-film electrodes.

  7. 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.

  8. Hysteresis in clay swelling induced by hydrogen bonding: accurate prediction of swelling states.

    PubMed

    Tambach, Tim J; Bolhuis, Peter G; Hensen, Emiel J M; Smit, Berend

    2006-01-31

    We perform grand-canonical molecular simulations to study the molecular mechanism of clay swelling hysteresis as a function of the relative humidity. In particular, we focus on the transition from the one- to the two-layer hydrate and the influence of three types of counterions (Li+, Na+, and K+). Our results cover the experimental relative humidity region where swelling and shrinking usually occur. We show that the thermodynamic origin of swelling hysteresis is a free-energy barrier separating the layered hydrates. This free-energy barrier is dominated by breaking and formation of hydrogen bonds between and within water layers. This network of water molecules is similar for all counterions, but the positions of these counterions depend upon their size. The relatively large K+ counterions show more affinity for clay surface adsorption, which increases the free-energy barrier and inhibits swelling. On the other hand, the relatively small Li+ counterions are quite well-accommodated in the water network, and thereby, they can form a new swelling state with a basal spacing of approximately 13.5 A. This new swelling state is an alternative explanation for the widely accepted simultaneous occurrence of two or more swelling phases. PMID:16430287

  9. Isolated Curves for Hyperelliptic Curve Cryptography

    E-print Network

    Wang, Wenhan

    2012-01-01

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

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

    E-print Network

    Lakes, Roderic

    1 Hysteresis Behaviour and Specific Damping Capacity of Negative Poisson's Ratio Foams Martz, E. O., Lakes, R. S., and Park, J. B. "Hysteresis behaviour and specific damping capacity of negative Poisson's ratio foams", Cellular Polymers, 15, 349-364, (1996). Abstract Open cell polyurethane foams have been

  11. Black hole-like hysteresis and accretion states in neutron star low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Muñoz-Darias, T.; Fender, R. P.; Motta, S. E.; Belloni, T. M.

    2014-10-01

    We have systematically studied a large sample of the neutron star low-mass X-ray binaries (LMXBs) monitored by the Rossi X-ray Timing Explorer (50 sources; 10000+ observations). We find that the hysteresis patterns between Compton-dominated and thermal-dominated states, typically observed in black hole LMXBs, are also common in neutron star systems. These patterns, which also sample intermediate states, are found when looking at the evolution of both X-ray colour and fast variability of 10 systems accreting below ˜30 per cent of the Eddington luminosity (LEdd). We show that hysteresis does not require large changes in luminosity and it is the natural form that state transitions take at these luminosities. At higher accretion rates, neutron stars do not show hysteresis, and they remain in a thermal-dominated, low-variability state, characterized by flaring behaviour and fast colour changes. Only at luminosities close to LEdd, are high variability levels seen again, in correspondence to an increase in the fractional contribution of the Comptonization component. We compare this behaviour with that observed in LMXBs harbouring black holes, showing that the spectral, timing and multiwavelength properties of a given source can be determined by its location in the fast variability-luminosity diagram, which, therefore, provides a common framework for neutron star and black hole accretion states.

  12. VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY

    E-print Network

    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

  13. VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY

    E-print Network

    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

  14. VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY

    E-print Network

    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

  15. Darwin curves and galaxy arms

    NASA Astrophysics Data System (ADS)

    He, Jin

    2014-07-01

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

  16. Neural networks based identification and compensation of rate-dependent hysteresis in piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Zhang, Xinliang; Tan, Yonghong; Su, Miyong; Xie, Yangqiu

    2010-06-01

    This paper presents a method of the identification for the rate-dependent hysteresis in the piezoelectric actuator (PEA) by use of neural networks. In this method, a special hysteretic operator is constructed from the Prandtl-Ishlinskii (PI) model to extract the changing tendency of the static hysteresis. Then, an expanded input space is constructed by introducing the proposed hysteretic operator to transform the multi-valued mapping of the hysteresis into a one-to-one mapping. Thus, a feedforward neural network is applied to the approximation of the rate-independent hysteresis on the constructed expanded input space. Moreover, in order to describe the rate-dependent performance of the hysteresis, a special hybrid model, which is constructed by a linear auto-regressive exogenous input (ARX) sub-model preceded with the previously obtained neural network based rate-independent hysteresis sub-model, is proposed. For the compensation of the effect of the hysteresis in PEA, the PID feedback controller with a feedforward hysteresis compensator is developed for the tracking control of the PEA. Thus, a corresponding inverse model based on the proposed modeling method is developed for the feedforward hysteresis compensator. Finally, both simulations and experimental results on piezoelectric actuator are presented to verify the effectiveness of the proposed approach for the rate-dependent hysteresis.

  17. Rational curves on Fermat hypersurfaces

    E-print Network

    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 $N_0> p^r(p^r-1)$.

  18. Noncrossing quantile regression curve estimation

    PubMed Central

    Bondell, Howard D.; Reich, Brian J.; Wang, Huixia

    2010-01-01

    Summary Since quantile regression curves are estimated individually, the quantile curves can cross, leading to an invalid distribution for the response. A simple constrained version of quantile regression is proposed to avoid the crossing problem for both linear and nonparametric quantile curves. A simulation study and a reanalysis of tropical cyclone intensity data shows the usefulness of the procedure. Asymptotic properties of the estimator are equivalent to the typical approach under standard conditions, and the proposed estimator reduces to the classical one if there is no crossing. The performance of the constrained estimator has shown significant improvement by adding smoothing and stability across the quantile levels. PMID:22822254

  19. A digitization scheme of sub-microampere current using a commercial comparator with hysteresis and FPGA-based wave union TDC

    NASA Astrophysics Data System (ADS)

    Wu, J.

    2013-01-01

    A digitization scheme of sub-microampere current using a commercial comparator with adjustable hysteresis and FPGA-based Wave Union TDC has been tested. The comparator plus a few passive components forms a current controlled oscillator and the input current is sent into the hysteresis control pin. The input current is converted into the transition times of the oscillations, which are digitized with a Wave Union TDC in FPGA and the variation of the transition times reflects the variation of the input current. Preliminary tests show that input charges < 25 fC can be measured at > 50 M samples/s without a preamplifier.

  20. The influence of temperature hysteresis at metal-semiconductor phase transition on current-voltage characteristic of VO 2 –based ceramics

    Microsoft Academic Search

    A. I. Ivon; V. R. Kolbunov; I. M. Chernenko

    2005-01-01

    The current-voltage characteristics of ceramics (wt%) 80VO2-15VPG-5Cu and 45VO2-15VPG-5Cu-35SnO2 were investigated (VPG—vanadium phosphate glass). After switching to high electric current, these characteristics show a hysteresis loop in the electric current increase-decrease cycle. The cause of hysteresis is the different phase transition temperatures in VO2 crystallites for transition from semiconductor phase to metallic phase and for the reverse transition. The distinction

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

    SciTech Connect

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

    2014-07-28

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

  2. A New Type Hysteresis Loop in SiN/GdFeCoSi/SiN Sandwich Structure

    NASA Astrophysics Data System (ADS)

    Zhao, Yanling; Wang, Shiqi; Shono, Keiji; Yu, Xiangyou; Lu, Mu; Zhai, Hongru

    A new type of inverted hysteresis loop was observed in an amorphous SiN/GdFeCoSi/SiN film, in which a magnetic GdFeCoSi layer with a thickness of 40 nm was sandwiched by SiN capping and buffer layers 5 nm thick. An inverted hysteresis loop with negative remanence appeared, when an applied field was perpendicular to the film plane, with remanance ratio of 0.4 and HC=120 Oe. An FMR experiment study showed that two magnetic phases existed in the system. A major magnetic phase had an easy-plane anisotropy and the other minor magnetic phase had an easy-normal anisotropy. By assuming an antiferromagnetic exchange coupling between them, the inverted loops can be explained.

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    Flow separation control by a non-thermal plasma actuator is considered for a NACA 0015 airfoil at a chord Reynolds number of 1.9 × 105. Static hysteresis in the lift coefficient is demonstrated for increasing and then decreasing sinusoidal voltage amplitude supplying a typical single dielectric barrier discharge actuator at the leading edge of the model. In addition to these open-loop experiments, unsteady surface pressure signals are examined for transient processes involving forced reattachment and natural separation. The results show that strong pressure oscillations in the relatively slow separation process, compared to reattachment, precede the ultimate massive flow separation. To enhance the contrast between the parts of the signal related to the attached flow and those related to the incipient separation, RMS estimate of filtered values of Cp is used to define a flow separation predictor that is implemented in feedback control. Two simple controllers are proposed, one based on a predefined threshold of the unsteady Cp and another that utilizes the flow separation predictor to identify incipient separation. The latter effectively leverages the hysteresis in the post-stall regime to reduce the electrical power consumed by the actuator while maintaining continuously attached flow.

  4. Elliptic Curves An Introduction

    E-print Network

    Babinkostova, Liljana

    . The growing practical relevance of elliptic curves in modern cryptography is another issue missing. This listElliptic Curves ­ An Introduction ­ Expanded notes from a mini-workshop held at Mary Immaculate. Group law on the cubic curve 29 4. Theta Functions 53 5. Rank two vector bundles on elliptic curves 75

  5. Elliptic Curves Number Theory

    E-print Network

    Babinkostova, Liljana

    Elliptic Curves Number Theory and Cryptography Second Edition © 2008 by Taylor & Francis Group, LLC Washington, Lawrence C. Elliptic curves : number theory and cryptography / Lawrence C. Washington. -- 2nd ed, elliptic curves started being used in cryptography and elliptic curve techniques were developed

  6. PHYSICAL REVIEW B 84, 224402 (2011) Anomalous magneto-optical Kerr hysteresis loops in Fe0.25TaS2

    E-print Network

    Kono, Junichiro

    , and superconductors. Charge density wave (CDW) states sometimes coexist, and compete with, superconductivity of the Kerr angle shows a clear hysteresis loop, but its shape sensitively changes with the wavelength. We was studied by magneto-optical (MO) Faraday effect.11 Real-time MO images revealed unusual dendritic domain

  7. Ionically-mediated electromechanical hysteresis in transition metal oxides

    SciTech Connect

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

    2012-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

  9. Capillary condensation, invasion percolation, hysteresis, and discrete memory

    SciTech Connect

    Guyer, R.A. [Department of Physics and Astronomy, University of Massachusetts, Amherst, Massachusetts 01003 (United States)] [Department of Physics and Astronomy, University of Massachusetts, Amherst, Massachusetts 01003 (United States); McCall, K.R. [Department of Physics, University of Nevada, Reno, Nevada 89557 (United States)] [Department of Physics, University of Nevada, Reno, Nevada 89557 (United States)

    1996-07-01

    A model of the capillary condensation process, i.e., of adsorption-desorption isotherms, having only pore-pore interactions is constructed. The model yields (1) hysteretic isotherms, (2) invasion percolation on desorption, and (3) hysteresis with discrete memory for interior chemical potential loops. All of these features are seen in experiment. The model is compared to a model with no pore-pore interactions (the Preisach model) and to a related model of interacting pore systems (the random field Ising model). The capillary condensation model differs from both. {copyright} {ital 1996 The American Physical Society.}

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

    SciTech Connect

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

    2012-01-01

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

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

    Microsoft Academic Search

    Y. Zhai; L. Vu-Quoc

    2005-01-01

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

  12. Hysteresis phenomena in the interaction process of conical shock waves: experimental and numerical investigations

    NASA Astrophysics Data System (ADS)

    Ben-Dor, G.; Vasiliev, E. I.; Elperin, T.; Chpoun, A.

    2001-12-01

    The interaction of two conical shock waves, one converging and straight and the other diverging and curvilinear, in an axisymmetric flow was investigated both experimentally and numerically. A double-loop hysteresis was discovered in the course of the experimental investigation. The double-loop hysteresis consisted of a major one, associated with the interaction between the boundary layer and the wave configuration, and a minor one, associated with the dual-solution phenomenon, which is known to be non-viscous-dependent. The minor hysteresis loop was found to be an internal hysteresis loop of the major one. As expected the numerical Euler calculations failed to detect the viscous-dependent major hysteresis loop but did succeed in obtaining the non-viscous-dependent minor (internal) hysteresis loop. In addition, multiple hysteresis loops, associated with the interaction between the shock wave configuration and the edge of the curvilinear mobile cone were also observed. The non-viscous minor hysteresis loop involved different overall shock wave reflection configurations, and the other hysteresis loops involved the same shock wave reflection configuration but different flow patterns.

  13. Investigation of Adjustable Current-Voltage Characteristics and Hysteresis Phenomena for Multiple-Peak Negative Differential Resistance Circuit

    NASA Astrophysics Data System (ADS)

    Gan, Kwang-Jow; Liang, Dong-Shong

    A multiple-peak negative differential resistance (NDR) circuit made of standard Si-based metal-oxide-semiconductor field-effect-transistor (MOS) and SiGe-based heterojunction bipolar transistor (HBT) is demonstrated. We can obtain a three-peak I-V curve by connecting three cascoded MOS-HBT-NDR circuits by suitably designing the MOS parameters. This novel three-peak NDR circuit possesses the adjustable current-voltage characteristics and high peak-to-valley current ratio (PVCR). We can adjust the PVCR values to be as high as 11.5, 6.5, and 10.3 for three peaks, respectively. Because the NDR circuit is a very strong nonlinear element, we discuss the extrinsic hysteresis phenomena in this multiple-peak NDR circuit. The effect of series resistance on hysteresis phenomena is also investigated. Our design and fabrication of the NDR circuit is based on the standard 0.35?m SiGe BiCMOS process.

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

    SciTech Connect

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

    2012-01-01

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

  15. Dynamics of Phase Transitions by Hysteresis Methods I

    E-print Network

    Bernd A. Berg; Urs M. Heller; Hildegard Meyer-Ortmanns; Alexander Velytsky

    2003-10-31

    In studies of the QCD deconfining phase transition or crossover by means of heavy ion experiments, one ought to be concerned about non-equilibrium effects due to heating and cooling of the system. Motivated by this, we look at hysteresis methods to study the dynamics of phase transitions. Our systems are temperature driven through the phase transition using updating procedures in the Glauber universality class. Hysteresis calculations are presented for a number of observables, including the (internal) energy, properties of Fortuin-Kasteleyn clusters and structure functions. We test the methods for 2d Potts models, which provide a rich collection of phase transitions with a number of rigorously known properties. Comparing with equilibrium configurations we find a scenario where the dynamics of the transition leads to a spinodal decomposition which dominates the statistical properties of the configurations. One may expect an enhancement of low energy gluon production due to spinodal decomposition of the Polyakov loops, if such a scenario is realized by nature.

  16. Hysteresis and saturation effects with the ALS lattice magnets

    SciTech Connect

    Keller, R.

    1995-04-01

    The primary purpose of the magnetic measurements performed on the ALS storage ring lattice magnets was to ascertain their compliance with the strict tolerances established for this third-generation synchrotron light source. In the course of the data evaluation, an approximation method has been developed that leads to four-parameter representations of all magnet transfer functions. The expressions for the transfer functions were now used to change the standard working point of the ALS storage ring from the upper to the lower hysteresis branches of all lattice magnet families, and later to ramp the ring from the customary 1.5 GeV to the maximum design energy of 1.9 GeV in one uninterrupted process that did not require any intermediate tune correction. This achievement is all the more remarkable as no remnant fields had directly been measured with any of these magnets. A specific remnant field effect that led to anomalous machine behavior-when trying to recuperate the betatron tunes on the lower hysteresis branch at standard energy could be ascribed to the C-shape of the quadrupole yokes.

  17. Fractal growth of liquid crystals as a hysteresis phenomenon

    NASA Astrophysics Data System (ADS)

    Chan, Ho-Kei; Dierking, Ingo

    2006-03-01

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

  18. Wavenumber selection and hysteresis in nonlinear baroclinic flow

    NASA Technical Reports Server (NTRS)

    Chou, Shih-Hung

    1995-01-01

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

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

    NSDL National Science Digital Library

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

    2009-04-14

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

  20. Molecular origin and functional consequences of digital signaling and hysteresis during Ras activation in lymphocytes.

    PubMed

    Chakraborty, Arup K; Das, Jayajit; Zikherman, Julie; Yang, Ming; Govern, Christopher C; Ho, Mary; Weiss, Arthur; Roose, Jeroen

    2009-01-01

    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. PMID:19366993

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  2. Measuring Extinction Curves of Lensing Galaxies

    E-print Network

    Christina McGough; Geoffrey C. Clayton; Karl D. Gordon; Michael J. Wolff

    2005-01-22

    We critique the method of constructing extinction curves of lensing galaxies using multiply imaged QSOs. If one of the two QSO images is lightly reddened or if the dust along both sightlines has the same properties then the method works well and produces an extinction curve for the lensing galaxy. These cases are likely rare and hard to confirm. However, if the dust along each sightline has different properties then the resulting curve is no longer a measurement of extinction. Instead, it is a measurement of the difference between two extinction curves. This "lens difference curve'' does contain information about the dust properties, but extracting a meaningful extinction curve is not possible without additional, currently unknown information. As a quantitative example, we show that the combination of two Cardelli, Clayton, & Mathis (CCM) type extinction curves having different values of R(V) will produce a CCM extinction curve with a value of R(V) which is dependent on the individual R(V) values and the ratio of V band extinctions. The resulting lens difference curve is not an average of the dust along the two sightlines. We find that lens difference curves with any value of R(V), even negative values, can be produced by a combination of two reddened sightlines with different CCM extinction curves with R(V) values consistent with Milky Way dust (2.1 extinction curves with R(V) values different than that of the lens difference curve. While it is not possible to determine the individual extinction curves making up a lens difference curve, there is information about a galaxy's dust contained in the lens difference curves.

  3. Investigation of magnetothermal and critical current hysteresis in polycrystals of low and high T(c) type II superconductors

    NASA Astrophysics Data System (ADS)

    Rezeq, Mohammed (Moh'd.)

    The model of Clem and Hao and others is extended to account for the enhancement of the Meissner effect observed in single crystals of hysteretic type II superconductors upon thermal cycling below Tc in static applied magnetic fields. Predictions are made about the features of the final closed thermal hysteretis loop achievable by extensive cycling and their dependence on the temperature limits T1 and T2 < Tc chosen for the cycles. A large variety of observations, by several workers, of a narrow peak of enhanced Meissner effect near Tc in polycrystalline type II superconductors upon slow warming in static applied fields after fast field cooling, are qualitatively and quantitatively accounted for by a model where we introduced the scheme developed above for single crystals into a weak-linked intergranular network (matrix). This "two tier" framework is then extended to describe the enhancement of the Meissner effect observed by Hyun by thermal cycling of weak-linked Nb3Sn below Tc in a static field. A simple framework is presented which quantitatively develops the proposal of Evetts and Glowacki that the superposition of the applied field H a and the return field, Hr of the magnetized grains, is the cause of the hysteretic behaviour of Ic in weak-linked high T c superconductors and the occurrence of a peak in Ic versus Ha descending and reascending, after an excursion to various values, denoted Hcycle, or after field cooling in different H cool. Observations by several workers on the dependence, of the position of four categories of peaks of Ic, on Hcycle and Hcool are reproduced by this model and yield estimates of the "compression" factor C in the linear dipole approximation, H r = C Mg. We also show that, ratios of the measured plateau values for the position of these peaks, lead to an estimate for C which is independent of H·g, the penetration field into the grains, and of the model chosen to calculate the dependence of the magnetization of the grains, Mg, on Ha. Instead of the artificial pseudo-Josephson - junction expression generally used by other workers in the analysis of Ic hysteresis phenomena, we develop a family of formulae based on the critical state concept applied to idealized planar geometry. Exploiting an especially simple case from this family of formulae we reproduce a panoply of experimental curves of Ic versus Ha displayed in the literature and exhibiting a variety, of features. Analysis of the extensive data of List et al reveals that our approach leads to results in accord with observations whereas the Josephson junction format does not. (Abstract shortened by UMI.)

  4. Magnetic Hysteresis Loop as a Tool for the Evaluation of Spheroidization of Cementites in Pearlitic Steels

    NASA Astrophysics Data System (ADS)

    Mohapatra, J. N.; Kamada, Y.

    2015-04-01

    Pearlitic Fe-0.76wt.% C binary alloy was isothermally annealed at 700 °C up to 100 h to study the spheroidization of cementites and its effect on both the mechanical and magnetic properties with the aim to use the magnetic techniques for the evaluation of spheroidization in steels. Micro-Vickers hardness, magnetic hysteresis loop (MHL) measurements, optical and scanning electron microscopy studies were carried out at various lengths of time by interrupting the test. Microhardness and coercivity were decreased with increase in annealing time due to reduction in dislocation pinning and magnetic domain wall pinning for the breaking of cementite lamella and their subsequent transformation to spheroidal form. The microhardness and coercivity showed a very good correlation with the change in microstructure indicating that MHL would be a suitable non-destructive evaluation tool for the evaluation of spheroidized pearlitic steels.

  5. 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.

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

    PubMed

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

    2014-01-01

    The discrete regenerative fuel cell is being developed as a residential power control that synchronizes with a renewables load which fluctuates significantly with the time and weather. The power of proton exchange membrane fuel cells can be scaled-up adjustably to meet the residential power demand. As a result, scale-ups from a basic unit cell with a 25 cm(2) active area create a serpentine flow-field on an active area of 100 cm(2) and take into account the excessive current and the remaining power obtained by stacking single cells. Operating a fuel cell utilising oxygen produced by the electrolyser instead of air improves the electrochemical reaction and the water balance. Furthermore, the performance test results with oxygen instead of air show almost no hysteresis, which results in the very stable operation of the proton exchange membrane fuel cell as well as the sustainable cycle of water by hydrogen and oxygen mediums. PMID:24699531

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

    PubMed Central

    Brady, Timothy F.; Oliva, Aude

    2012-01-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-01-24

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

  10. Twinned principal curves

    Microsoft Academic Search

    Jos Koetsier; Ying Han; Colin Fyfe

    2004-01-01

    Principal Curves are extensions of Principal Component Analysis and are smooth curves, which pass through the middle of a data set. We extend the method so that, on pairs of data sets which have underlying non-linear correlations, we have pairs of curves which go through the ‘centre’ of data sets in such a way that the non-linear correlations between the

  11. Total fatigue curve

    SciTech Connect

    Sosnovskii, L.A.; Makhutov, N.A. [A.A. Blagonravov Inst. of Machine Engineering, Moscow (Russian Federation)

    1995-11-01

    The fatigue failure mechanisms operative on different segments of the total fatigue curve are discussed. The need for experimental determination of this curve is emphasized; once known, this curve will make possible a deeper insight into the transitional zones associated with a change in the cumulative fatigue damage mechanism.

  12. A compact single-pass architecture for hysteresis thresholding and component labeling

    Microsoft Academic Search

    Mayssaa Al Najjar; Swetha Karlapudi; Magdy A. Bayoumi

    2010-01-01

    Hysteresis thresholding offers enhanced edge\\/object detection in the presence of noise. However, due to its recursive nature, it requires a lot of memory and execution time. Thus, it is restricted and sometimes totally avoided in streaming processors with limited memory. We propose an efficient architecture coupling hysteresis thresholding with component labeling and feature extraction in a single pass over the

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

    Microsoft Academic Search

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

    2001-01-01

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

  14. Hysteresis compensation in PZT bimorph mirrors: Preisach's classical and non-linear models

    Microsoft Academic Search

    Alfredo Dubra; John S. Massa; Carl Paterson

    2005-01-01

    A number of reflective wavefront correctors used in adaptive optics are based on the use of piezoelectric effect, either in piston, tip\\/tilt or curvature devices. The relation between the voltage applied to drive these devices and the mechanical response always presents hysteresis to some extent. In this work we study the performance of Preisach's classical and non-linear models of hysteresis

  15. Onset of water stress, hysteresis in plant conductance, and hydraulic lift: Scaling soil water dynamics

    E-print Network

    Katul, Gabriel

    Onset of water stress, hysteresis in plant conductance, and hydraulic lift: Scaling soil water hysteresis in canopy conductance, hydraulic lift, and compensatory root water uptake during extended drying effective is dictated by soil hydraulic properties and surrogates for atmospheric water vapor demand

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

    E-print Network

    Tan, Xiaobo

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

  17. Continuum Damage Mechanics for hysteresis and fatigue of quasi-brittle materials and structures

    E-print Network

    Continuum Damage Mechanics for hysteresis and fatigue of quasi-brittle materials and structures R in the present work that damage, from the Continuum Damage Mechanics point of view, may be seen as the link@lmt.ens-cachan.fr, tel: 33 1 47 40 74 60, fax: 33 1 47 40 74 65 #12;CONTINUUM DAMAGE MECHANICS FOR HYSTERESIS AND FATIGUE

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

    E-print Network

    Sethna, James P.

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

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

    E-print Network

    Sethna, James P.

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

  20. Interval Maps with Hysteresis A thesis submitted to the University of Strathclyde

    E-print Network

    Berkolaiko, Gregory

    Dynamics of Interval Maps with Hysteresis A thesis submitted to the University of Strathclyde of multistate maps, maps with hysteresis. The map under consideration is a collection of two continuous function is applied. We study two di#11;erent aspects of such maps: topological and combinato- rial

  1. A time-based double band hysteresis current regulation strategy for single-phase multilevel inverters

    Microsoft Academic Search

    P. C. Loh; G. H. Bode; D. G. Holmes; T.A. Lipo

    2002-01-01

    Most multilevel inverter hysteresis current regulators use either multiple hysteresis bands, or a time-based switching logic that forces the current error back to zero by recursively stepping through successive voltage levels. Of these two alternatives, the time-based approach has the merit of only requiring simple analog circuitry and digital logic to implement the voltage level selection process for inverters of

  2. From principal curves to granular principal curves.

    PubMed

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

    2014-06-01

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

  3. Note: Simple hysteresis parameter inspector for camera module with liquid lens.

    PubMed

    Chen, Po-Jui; Liao, Tai-Shan; Hwang, Chi-Hung

    2010-05-01

    A method to inspect hysteresis parameter is presented in this article. The hysteresis of whole camera module with liquid lens can be measured rather than a single lens merely. Because the variation in focal length influences image quality, we propose utilizing the sharpness of images which is captured from camera module for hysteresis evaluation. Experiments reveal that the profile of sharpness hysteresis corresponds to the characteristic of contact angle of liquid lens. Therefore, it can infer that the hysteresis of camera module is induced by the contact angle of liquid lens. An inspection process takes only 20 s to complete. Thus comparing with other instruments, this inspection method is more suitable to integrate into the mass production lines for online quality assurance. PMID:20515182

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

    PubMed

    Bhattacharyya, Joydeb; Pal, Samares

    2015-03-01

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

  5. Hysteresis in multiphase microfluidics at a T-junction.

    PubMed

    Zagnoni, Michele; Anderson, Jamie; Cooper, Jonathan M

    2010-06-15

    Multiphase microfluidics offer a wide range of functionalities in the fields of fluid dynamics, biology, particle synthesis, and, more recently, also in logical computation. In this article, we describe the hysteresis of immiscible, multiphase flow obtained in hydrophilic, microfluidic systems at a T-junction. Stable and unstable state behaviors, in the form of segmented and parallel flow patterns of oil and water, were reliably produced, depending upon the history of the flow rates applied to the phases. The transition mechanisms between the two states were analyzed both experimentally and using numerical simulations, describing how the physical and fluid dynamic parameters influenced the hysteretic behavior of the flow. The characteristics of these multiphase systems render them suitable to be used as pressure comparators and also for the implementation of microfluidic logic operations. PMID:20465264

  6. Wafer-level hysteresis-free resonant carbon nanotube transistors.

    PubMed

    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

  7. 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.

  8. Hysteresis in Magnetic Shape Memory Composites: Modeling and Simulation

    E-print Network

    Conti, Sergio; Rumpf, Martin

    2015-01-01

    Magnetic shape memory alloys are characterized by the coupling between a structural phase transition and magnetic one. This permits to control the shape change via an external magnetic field, at least in single crystals. Composite materials with single-crystalline particles embedded in a softer matrix have been proposed as a way to overcome the blocking of the transformation at grain boundaries. We investigate hysteresis phenomena for small NiMnGa single crystals embedded in a polymer matrix for slowly varying magnetic fields. The evolution of the microstructure is studied within the rate-independent variational framework proposed by Mielke and Theil (1999). The underlying variational model incorporates linearized elasticity, micromagnetism, stray field and a dissipation term proportional to the volume swept by the phase boundary. The time discretization is based on an incremental minimization of the sum of energy and dissipation. A backtracking approach is employed to approximately ensure the global minimali...

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

    E-print Network

    Hu, M B; Wang, W X; Wu, Q S; Wu, Y H; Hu, Mao-Bin; Jiang, Rui; Wang, Wen-Xu; Wu, Qing-Song; Wu, Yong-Hong

    2006-01-01

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

  10. Parameterization and applications of Catmull–Rom curves

    Microsoft Academic Search

    Cem Yuksel; Scott Schaefer; John Keyser

    2011-01-01

    The behavior of Catmull–Rom curves heavily depends on the choice of parameter values at the control points. We analyze a class of parameterizations ranging from uniform to chordal parameterization and show that, within this class, curves with centripetal parameterization contain properties that no other curves in this family possess. Researchers have previously indicated that centripetal parameterization produces visually favorable curves

  11. An air-cooled Litz wire coil for measuring the high frequency hysteresis loops of magnetic samples—A useful setup for magnetic hyperthermia applications

    NASA Astrophysics Data System (ADS)

    Connord, V.; Mehdaoui, B.; Tan, R. P.; Carrey, J.; Respaud, M.

    2014-09-01

    A setup for measuring the high-frequency hysteresis loops of magnetic samples is described. An alternating magnetic field in the range 6-100 kHz with amplitude up to 80 mT is produced by a Litz wire coil. The latter is air-cooled using a forced-air approach so no water flow is required to run the setup. High-frequency hysteresis loops are measured using a system of pick-up coils and numerical integration of signals. Reproducible measurements are obtained in the frequency range of 6-56 kHz. Measurement examples on ferrite cylinders and on iron oxide nanoparticle ferrofluids are shown. Comparison with other measurement methods of the hysteresis loop area (complex susceptibility, quasi-static hysteresis loops, and calorific measurements) is provided and shows the coherency of the results obtained with this setup. This setup is well adapted to the magnetic characterization of colloidal solutions of magnetic nanoparticles for magnetic hyperthermia applications.

  12. Thermochromic liquid crystal thermography: Hysteresis, illumination and imaging system effects, image processing and applications

    NASA Astrophysics Data System (ADS)

    Anderson, Michael Robert

    Thermochromic Liquid Crystals (TLC's) reflect incident light iridescently depending on their temperature and are used extensively in thermography. Recent advances involve using the reflected color (e.g. hue) from digital images of surfaces coated with TLC's to produce full-field global surface temperature distributions. These advances have made it important to take a deeper look into factors influencing the hue-temperature behavior of TLC's and the effects of image processing. The behavior of five different microencapsulated TLC's (both broad-band and narrow-band) has been investigated. Although TLC's have generally been thought to be reversible and repeatable, all five of these TLC's were found to exhibit a similar hysteresis behavior when cooled rather than heated. This hysteresis is characterized by a decrease in reflectivity and a shift in the temperature associated with the peak reflected intensity during cooling relative to heating. The combined effect is a shift in the hue-temperature calibration of the TLC. This shift results in temperature biases during cooling (relative to heating), of approximately 20% of the useful calibration range for broadband TLC's and as high as 40% to 60% of the useful calibration range for narrow-band TLC's. The magnitude of the hysteresis increases with an increase in the peak temperature prior to cooling. Repeatable heating (and cooling) calibrations are obtained when the TLC is initially cooled below (or heated above) an apparent reset temperature. These reset temperatures appear to be related to the red start temperature for heating and the blue stop temperature (about 20°C to 25°C above the top of the useful calibration range) for cooling. A permanent shift in the hue-temperature calibration (characterized by a decrease in reflectivity and a shift in the temperature associated with the peak reflected intensity) was observed during the tests. This shift appears to be due to high temperature exposure (60°C-80°C). A theoretical model of a TLC imaging system was developed to investigate some of the factors affecting TLC hue- temperature behavior. These factors include the spectral distribution of the illumination source and UV filter, the surface reflection due to both the TLC and background, the TLC coating thickness and the sensing device (camera) spectral characteristics and gain settings. Results from the model are compared to experimental measurements. It is found that typical measurements cannot be explained by a TLC reflectivity model with a monochromatic spike or narrow bandwidth, the model that is often assumed. A model with TLC reflection over a relatively broad band of wavelengths results in good agreement between the model and measurements. The significance of background reflection, which commonly accounts for 30% to 50% of the reflected light, is examined. It is shown that the background reflection tends to attenuate the hue-temperature calibration curve toward the background hue value. Five illumination sources are compared to examine their effect on the hue- temperature behavior. It is found that ``full spectrum'' bulbs, which have a relatively uniform radiant intensity across the visible spectrum, tend to have the lowest temperature measurement uncertainties and the broadest useful ranges, which are desirable calibration attributes. An interactive liquid crystal image processing toolbox was developed in MATLAB to assist in the analysis and processing of TLC images and in the subsequent calculation of heat transfer information. An overview of this toolbox is provided.

  13. Research on elliptic curve cryptography

    Microsoft Academic Search

    Qizhi Qiu; Qianxing Xiong

    2004-01-01

    There are many drawbacks in current encryption algorithms in respect of security, real-time performance and so on, and researchers are presenting various algorithms. Among them, the elliptic curve cryptography (ECC) is evolving as an important cryptography, and shows a promise to be an alternative of RSA. Small size, high security and other features characterize ECC. Based on the theory of

  14. Homemade Laser Show

    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.

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

    PubMed

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

    2014-01-01

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

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

    PubMed Central

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

    2014-01-01

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

  17. The Diane Rehm Show

    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.

  18. Producing Turkeys for Show

    E-print Network

    Thornberry, Fredrick D.

    2005-12-14

    . Use top-quality feeds. 4. Follow recommended management practices during the entire brooding and growing period. 5. Cull birds closely and select the show entry properly. Purchasing Poults Most youth livestock shows have rules and regulations governing... with an approved worm- ing compound. a73 Check turkeys monthly for parasites. Pay particular attention to skin around the vent area. Control external para- sites (lice, mites, etc.) with applications of Sevin ? dust. a73 Fire ants can cause skin blisters and must...

  19. Understand Centrifugal Compressor stage curves

    SciTech Connect

    Stadler, E.L.

    1986-08-01

    Multistage Centrifugal Compressor Performance is generally presented in the form of a composite curve showing discharge pressure and bhp plotted as a function of capacity. This composite curve represents the cumulative performance of each stage performance curve. A simple yet quite accurate means of measuring compressor total performance is to test each stage as a single-stage compressor, usually on air with atmospheric inlets. Stage curves are then generated from the test data and three important variables are plotted: head coefficient, work coefficient and adiabatic efficiency. These variables are plotted against a normalized flow coefficient, Q/N, which is inlet volume flow (cfm) divided by impeller speed (rpm). The nomenclature used to define these stage variables changes from manufacturer to manufacturer; however, the parameters presented are the same. An understanding of each parameter's theoretical derivation and determination from test data will help the engineer reviewing test curves to be more cognizant of the interrelationships between these variables; specifically, how they affect overall machine pressure rise and power consumption.

  20. Hysteresis phenomena and multipulse formation of a dissipative system in a passively mode-locked fiber laser

    SciTech Connect

    Liu Xueming [State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119 (China)

    2010-02-15

    A model describing the dissipative soliton evolution in a passively mode-locked fiber laser is proposed by using the nonlinear polarization rotation technique and the spectral filtering effect. It is numerically found that the laser alternately evolves on the stable and unstable mode-locking states as a function of the pump strength. Numerical simulations show that the passively mode-locked fiber lasers with large net normal dispersion can operate on multiple pulse behavior and hysteresis phenomena. The experimental observations confirm the theoretical predictions. The theoretical and experimental results achieved are qualitatively distinct from those observed in net-anomalous-dispersion conventional-soliton fiber lasers.

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

    PubMed Central

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

    2013-01-01

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

  2. Research on the dynamic hysteresis loop model of the residence times difference (RTD)-fluxgate.

    PubMed

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

    2013-01-01

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

  3. 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.

  4. Showing What They Know

    ERIC Educational Resources Information Center

    Cech, Scott J.

    2008-01-01

    Having students show their skills in three dimensions, known as performance-based assessment, dates back at least to Socrates. Individual schools such as Barrington High School--located just outside of Providence--have been requiring students to actively demonstrate their knowledge for years. The Rhode Island's high school graduating class became…

  5. Demonstration Road Show

    NSDL National Science Digital Library

    Shropshire, Steven

    2009-04-06

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

  6. Hide / Show Animal Ethics

    E-print Network

    New South Wales, University of

    the Ethics Secretariat for information on Animal Ethics Courses available at UNSW. All new added personnelHide / 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

  7. Stage a Water Show

    ERIC Educational Resources Information Center

    Frasier, Debra

    2008-01-01

    In the author's book titled "The Incredible Water Show," the characters from "Miss Alaineus: A Vocabulary Disaster" used an ocean of information to stage an inventive performance about the water cycle. In this article, the author relates how she turned the story into hands-on science teaching for real-life fifth-grade students. The author also…

  8. What Do Maps Show?

    ERIC Educational Resources Information Center

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

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

  9. The Ozone Show.

    ERIC Educational Resources Information Center

    Mathieu, Aaron

    2000-01-01

    Uses a talk show activity for a final assessment tool for students to debate about the ozone hole. Students are assessed on five areas: (1) cooperative learning; (2) the written component; (3) content; (4) self-evaluation; and (5) peer evaluation. (SAH)

  10. Show Me the Way

    ERIC Educational Resources Information Center

    Dicks, Matthew J.

    2005-01-01

    Because today's students have grown up steeped in video games and the Internet, most of them expect feedback, and usually gratification, very soon after they expend effort on a task. Teachers can get quick feedback to students by showing them videotapes of their learning performances. The author, a 3rd grade teacher describes how the seemingly…

  11. Source Discrimination from Magnitude Curve

    NASA Astrophysics Data System (ADS)

    Nguyen, B. V.

    2011-12-01

    Theoretical and numerical examinations on "magnitude curves" from explosions and earthquakes with various source time functions were made. The body-wave magnitude curve mb (T) is obtained by applying a series of narrow band-pass filters (0.75 f0 - 1.25 f0) at center frequencies f0 to instrument-corrected ground motions of P waves (0.1 <= f <= 10 Hz). The mb formula of Veith and Clawson (1972) is employed at these center periods. At each station, both raw and corrected magnitude curves have the same slopes and shapes with period since the correction factor depends not on frequency but on source depth and station distance. The surface-wave magnitude MS (T) curve is similarly obtained in the period range from 2 to 100 sec. The mb magnitude curves from an explosion source show sharp peaks with slopes +1 and -1 as well as +2 and -2 (1.5 and -1.5 for MS (T) magnitude curves) varied with log period at 0 or 5 km source depth. The mb magnitude curves from earthquakes are flat plateaus (slopes of 0; -0.5 for MS (T) curves) varied with log period at 0 or 5 km depth. For the case of an explosion plus tectonic release, a sharp magnitude peak for the explosion component and a flat plateau of slope 0 for the tectonic component for mb (T) (nearly flat plateau of slope -0.5 for MS (T)) are shown. The long-period magnitude falloff is controlled by the power dependence of T^(p+0-2) for body waves or T^(p+0.5-2) for surface waves: the T^p of the far-field (source) spectrum, the T^(-2) of amplitude to magnitude, T^0 of the far-field body-wave amplitude factor, and T^0.5 of the far-field surface-wave amplitude factor. The value of p is -2, -1, 0, +1, or +2. This approach is tested with ten events: five are known earthquakes and five are known explosions. With respect to body waves, the average body-wave magnitude curves for known explosion sources indicate triangular peaks of slopes +1 and -1 as well as +2 and -2 with log period. Known earthquake sources exhibit flat body-wave magnitude peaks with slopes 0 and the flanks with slopes +-1 and/or +-2. Known explosion events with tectonic release exhibit two body-wave magnitude peaks: one is an explosion triangular peak and the second peak which can be thought as slope combinations from explosion and earthquake.

  12. 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(+).

  13. A kill curve for Phanerozoic marine species

    NASA Technical Reports Server (NTRS)

    Raup, D. M.

    1991-01-01

    A kill curve for Phanerozoic species is developed from an analysis of the stratigraphic ranges of 17,621 genera, as compiled by Sepkoski. The kill curve shows that a typical species' risk of extinction varies greatly, with most time intervals being characterized by very low risk. The mean extinction rate of 0.25/m.y. is thus a mixture of long periods of negligible extinction and occasional pulses of much higher rate. Because the kill curve is merely a description of the fossil record, it does not speak directly to the causes of extinction. The kill curve may be useful, however, to li inverted question markmit choices of extinction mechanisms.

  14. Molecular thermal hysteresis in helix-dimer formation of sulfonamidohelicene oligomers in solution.

    PubMed

    Shigeno, Masanori; Kushida, Yo; Yamaguchi, Masahiko

    2013-07-29

    Sulfonamidohelicene oligomers up to the nonamer level were synthesized by the repeated coupling reactions of a building block. A tetramer formed a helix dimer in 1,3-difluorobenzene, which unfolded to a random coil with heating. This structural change exhibited thermal hysteresis in which different thermal responses were observed in the course of temperature increase and decrease. The feature of the hysteresis was examined under different heating/cooling modes, and the mechanisms are discussed on the basis of the population change and the presence of an induction period. A proposal regarding the use of thermal hysteresis for sensing a temperature increase/decrease is also given. PMID:23775763

  15. Effects of annealing, pre-tension and mounting on the hysteresis of polymer strain sensors

    NASA Astrophysics Data System (ADS)

    Abang, Ada; Webb, David J.

    2014-01-01

    When exposed to high levels of strain, polymer optical fibre grating sensors recorded in poly(methyl methacrylate) based fibre often exhibit hysteresis in the response of their Bragg wavelength to strain. We demonstrate that the application of pre-tension and annealing of the polymer fibre can reduce this hysteresis when the fibre is suspended freely between two supports, but much better performance is obtained when the sensor is attached directly to a substrate. In this case, the hysteresis can be lessened by more than a factor of 12.

  16. 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.

  17. On the Rayleigh law of magnetization: A new mathematical model of hysteresis loops

    NASA Astrophysics Data System (ADS)

    Ponomarev, Yu. F.

    2007-11-01

    A mathematical model of magnetic hysteresis loops for weak ac magnetic fields, which is applicable for both symmetrical hysteresis loops that are described by the Rayleigh law of magnetization and asymmetrical loops that are not, has been formulated. The asymmetrical hysteresis loops take place when the ferromagnet is affected, along with an ac magnetizing field, by a dc field. The frequency spectrum of a ferromagnet magnetization has been analyzed as a time function. A technique for experimental determination of parameters that enter into this model is proposed, which uses amplitudes and phases of the first three magnetization harmonic components (the first, the second, and the third ones).

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

    NASA Astrophysics Data System (ADS)

    Liu, Yanfang; Shan, Jinjun; Gabbert, Ulrich

    2015-01-01

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

  19. 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…

  20. Show-Me Magazine

    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.

  1. Keeping Show Pigs Healthy

    E-print Network

    Lawhorn, D. Bruce

    2006-10-13

    within a well-managed farm ? 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... of disease problems. 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...

  2. Viewing television talk shows

    Microsoft Academic Search

    Alan M. Rubin; Mary M. Step

    1997-01-01

    We examined how motivation, audience activity, and attitudes influenced the likelihood of watching societal?issue and relational topics on television talk programs. Path analysis supported differences in ritualized and instrumental motives for watching talk shows. Information and exciting?entertainment motivation predicted greater’ realism of, affinity with, involvement with, and intent to watch talk television. Pass?time motivation predicted reduced affinity with and intent

  3. Mars Slide Show

    NASA Technical Reports Server (NTRS)

    2006-01-01

    15 September 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a landslide that occurred off of a steep slope in Tithonium Chasma, part of the vast Valles Marineris trough system.

    Location near: 4.8oS, 84.6oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Autumn

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

    PubMed

    Othman, Sarbaz; Thomson, Robert; Lannér, Gunnar

    2010-01-01

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

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

    PubMed Central

    Othman, Sarbaz; Thomson, Robert; Lannér, Gunnar

    2010-01-01

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

  6. 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.

  7. The Curved Cube

    NSDL National Science Digital Library

    Hill, David R.

    2003-02-24

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

  8. Crystallography on Curved Surfaces

    Microsoft Academic Search

    Vincenzo Vitelli; Julius Lucks; David Nelson

    2007-01-01

    We present a theoretical and numerical study of the static and dynamical properties that distinguish two dimensional curved crystals from their flat space counterparts. Experimental realizations include block copolymer mono-layers on lithographically patterned substrates and self-assembled colloidal particles on a curved interface. At the heart of our approach lies a simple observation: the packing of interacting spheres constrained to lie

  9. 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…

  10. Tempo curves considered harmful

    Microsoft Academic Search

    Peter Desain; Henkjan Honing

    1993-01-01

    In the literature of musicology, computer music research and the psychology of music, timing or tempo measurements are mostly presented in the form of continuous curves. The notion of these tempo curves is dangerous, despite its widespread use, because it lulls its users into the false impression that a continuous concept of temporal flow has an independent existence, a musical

  11. Pairings on hyperelliptic curves

    Microsoft Academic Search

    Jennifer Balakrishnan; Juliana Belding; Sarah Chisholm; Kirsten Eisentraeger; Katherine E. Stange; Edlyn Teske

    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.

  12. The J-Meter Coercivity Spectrometer - Hysteresis Loop, IRM Acquisition Spectrum and Viscosity Spectrum in 6 Minutes

    NASA Astrophysics Data System (ADS)

    Enkin, R. J.; Nourgaliev, D.; Iassonov, P.

    2009-05-01

    The J-Meter Coercivity Spectrometer uses an innovative robust design for measuring a geological sample's magnetic hysteresis loop, IRM acquisition spectrum and viscosity spectrum in 6 minutes. With this tool, several labs around the world have been able measure large sample collections and develop useful magnetic proxies for a variety of paleoclimate, diagenesis and other studies. The main element of the J-meter is a pulse magnetometer, in which an electromotive force pulse is induced in an array of pick-up coils by the magnetic field of a sample moving at a high speed past the coils. The sample is placed near the rim of a 50 cm diameter plexiglas disk which rotates 18 times a second through the pole pieces of an electromagnet. Both the induced and remanent magnetization are measured during each rotation of the disk. Induced magnetization for hysteresis loops are measure with a set of pick-up coils mounted directly on the pole pieces, similar to the geometry used for a vibrating sample magnetometer. The magnetic remanence is measured with a second array of coils situated away from the electromagnet and surrounded by a three-layer mu-metal shield. The electromagnet field is ramped up to 500 mT, and the down to the opposite polarity (-500 mT). The J meter is called a coercivity spectrometer because it is particularly well suited to measuring the IRM acquisition curve with sufficient sensitivity and resolution to take the derivative which defines the coercivity spectrum. To finish each measurement, the magnetic field is cut to zero and the viscous demagnetization is monitored for 100s, mostly following a log(time) relationship but with perturbations determined by the grain size distribution of the finest grains. A suite of analysis programs have been developed to determine hysteresis parameters and S-ratios, and to characterize coercivity and viscosity spectra. We present a series of applications demonstrating the power of the J-Meter to trace sediment sources, paleoclimate variations and diagenetic alteration associate with bacterial activity.

  13. Hysteresis Affects Approximate Number Discrimination in Young Children

    PubMed Central

    Odic, Darko; Hock, Howard; Halberda, Justin

    2015-01-01

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

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

    PubMed

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

    2014-07-01

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

  15. 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.

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

    NASA Astrophysics Data System (ADS)

    Sharma, Auditya; Andreanov, Alexei; Müller, Markus

    2014-10-01

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

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

    PubMed

    Sharma, Auditya; Andreanov, Alexei; Müller, Markus

    2014-10-01

    We study avalanches along the hysteresis loop of long-range interacting spin glasses with continuous XY symmetry, which serves as a toy model of granular superconductors with long-range and frustrated Josephson couplings. We identify sudden jumps in the T=0 configurations of the XY phases as an external field is increased. They are initiated by the softest mode of the inverse susceptibility matrix becoming unstable, which induces an avalanche of phase updates (or spin alignments). We analyze the statistics of these events and study the correlation between the nonlinear avalanches and the soft mode that initiates them. We find that the avalanches follow the directions of a small fraction of the softest modes of the inverse susceptibility matrix, similarly as was found in avalanches in jammed systems. In contrast to the similar Ising spin glass (Sherrington-Kirkpatrick) studied previously, we find that avalanches are not distributed with a scale-free power law but rather have a typical size which scales with the system size. We also observe that the Hessians of the spin-glass minima are not part of standard random matrix ensembles as the lowest eigenvector has a fractal support. PMID:25375434

  18. 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.

  19. American History Picture Show

    NSDL National Science Digital Library

    Ms. Bennion

    2009-11-23

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

  20. Solar Light Show

    NSDL National Science Digital Library

    de Nie, Michael Willem.

    Over the last few days, the Earth has been buffeted by a geomagnetic storm caused by a major solar flare. In addition to disruptions in radio, telecommunications, and electric service, the flare may also produce a dramatic light show as it peaks tonight. Weather permitting, the aurora borealis, or northern lights, may be visible as far south as Washington, D.C. The best viewing time will be local midnight. The sun is currently at the peak of its eleven-year solar cycle, spawning flares and "coronal mass ejections" (CME), violent outbursts of gas from the sun's corona that can carry up to 10 billion tons of electrified gas traveling at speeds as high as 2000 km/s. Geomagnetic storms result when solar winds compress the magnetosphere, sometimes interfering with electric power transmission and satellites, but also creating beautiful aurorae, as many stargazers hope will occur tonight.

  1. Show-Me Center

    NSDL National Science Digital Library

    The Show-Me Center, located at the University of Missouri, is a math education project of the National Science Foundation. The center's Web site "provides information and resources needed to support selection and implementation of standards-based middle grades mathematic curricula." There are some sample lesson plans offered, but most of the material is solely for use by teachers. Five different middle grade math curriculums were started in 1992, and now, the implementation and results of each curriculum are presented on this site. Teachers can examine each one, view video clips, and read case studies and other reports to choose which parts of the curriculums would fit best into their own classes.

  2. Comprehensive modelling of dynamic hysteresis loops in the rolling and transverse directions for transformer laminations

    NASA Astrophysics Data System (ADS)

    Baghel, A. P. S.; Gupta, A.; Chwastek, K.; Kulkarni, S. V.

    2015-04-01

    Magnetic properties of grain-oriented materials are affected by hysteresis, anisotropy and dynamic effects. The attempts to describe dynamic hysteresis loops are usually limited to the rolling direction (RD). On the other hand, modelling of magnetic properties for the transverse direction (TD) is important for numerical analysis of core-joints and corner regions in transformers. For this direction, hysteresis loops reveal complex shapes particularly for dynamic magnetization conditions. This paper presents a comprehensive approach for modelling of dynamic hysteresis loops in RD and TD. This work uses the magnetic viscosity-based approach, which is able to describe irregular widening of dynamic loops. The loss separation scheme is also considered for both principal directions. Variations of loss components with frequency for both directions are discussed. The computed dynamic loops in RD and TD are in a close agreement with experimental ones.

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

    E-print Network

    Southern California, University of

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

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

    E-print Network

    Laughlin, David E.

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

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  6. Abstract --In electromagnetic applications, hysteresis phenomena in magnetic materials are responsible of

    E-print Network

    Boyer, Edmond

    13. M M Abstract -- In electromagnetic applications, hysteresis phenomena in magnetic materials, electrical engineering is concerned with energy efficiency. In addition, in the case of electromagnetic.. Following the predefined criteria such as induction response and losses computation, some compatible models

  7. Public medical shows.

    PubMed

    Walusinski, Olivier

    2014-01-01

    In the second half of the 19th century, Jean-Martin Charcot (1825-1893) became famous for the quality of his teaching and his innovative neurological discoveries, bringing many French and foreign students to Paris. A hunger for recognition, together with progressive and anticlerical ideals, led Charcot to invite writers, journalists, and politicians to his lessons, during which he presented the results of his work on hysteria. These events became public performances, for which physicians and patients were transformed into actors. Major newspapers ran accounts of these consultations, more like theatrical shows in some respects. The resultant enthusiasm prompted other physicians in Paris and throughout France to try and imitate them. We will compare the form and substance of Charcot's lessons with those given by Jules-Bernard Luys (1828-1897), Victor Dumontpallier (1826-1899), Ambroise-Auguste Liébault (1823-1904), Hippolyte Bernheim (1840-1919), Joseph Grasset (1849-1918), and Albert Pitres (1848-1928). We will also note their impact on contemporary cinema and theatre. PMID:25273491

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

    Microsoft Academic Search

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

    2000-01-01

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

  9. Three-Phase Four-Leg Inverter Based on Voltage Hysteresis Control

    Microsoft Academic Search

    Xiaoyong Zhang; Jun Wang; Chuan Li

    2010-01-01

    As the output unit of variety distributed generation systems, the final power quality is determined by three-phase four-leg inverter. For the three-phase four-leg inverter, this paper presents a dynamic reference voltage hysteresis control scheme. Firstly, based on the existing hysteresis comparison method, this method improves the systems control rapidity and stability through designing differential negative feedback. Secondly, through theoretical analysis

  10. Dynamic interface charge governing the current-voltage hysteresis in perovskite solar cells.

    PubMed

    Zhang, Huimin; Liang, Chunjun; Zhao, Yong; Sun, Mengjie; Liu, Hong; Liang, Jingjing; Li, Dan; Zhang, Fujun; He, Zhiqun

    2015-04-01

    The accumulation of mobile ions causes space charge at interfaces in perovskite solar cells. There is a slow dynamic process of ion redistribution when the bias is changed. The interface charge affects band bending and thus the photocurrent of the solar cells. Consequently the dynamic process of the interface charge governs the current-voltage hysteresis. Very low interface charge density leads to hysteresis-free devices. PMID:25772648

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

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

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

  12. Hot-carrier-induced degradation of drain current hysteresis and transients in thin gate oxide floating body partially depleted SOI nMOSFETs

    Microsoft Academic Search

    J. M. Rafí; E. Simoen; K. Hayama; A. Mercha; F. Campabadal; H. Ohyama; C. Claeys

    2006-01-01

    The impact of hot-carrier degradation on drain current (ID) hysteresis and switch-off ID transients of thin gate oxide floating body PD SOI nMOSFETs is analyzed. An extended characterization of these floating body effects (FBEs) is carried out for a wide range of transistor geometries and bias conditions. The results show a link between the hot-carrier-induced damage of the front channel

  13. The Great Cometary Show

    NASA Astrophysics Data System (ADS)

    2007-01-01

    The ESO Very Large Telescope Interferometer, which allows astronomers to scrutinise objects with a precision equivalent to that of a 130-m telescope, is proving itself an unequalled success every day. One of the latest instruments installed, AMBER, has led to a flurry of scientific results, an anthology of which is being published this week as special features in the research journal Astronomy & Astrophysics. ESO PR Photo 06a/07 ESO PR Photo 06a/07 The AMBER Instrument "With its unique capabilities, the VLT Interferometer (VLTI) has created itself a niche in which it provide answers to many astronomical questions, from the shape of stars, to discs around stars, to the surroundings of the supermassive black holes in active galaxies," says Jorge Melnick (ESO), the VLT Project Scientist. The VLTI has led to 55 scientific papers already and is in fact producing more than half of the interferometric results worldwide. "With the capability of AMBER to combine up to three of the 8.2-m VLT Unit Telescopes, we can really achieve what nobody else can do," added Fabien Malbet, from the LAOG (France) and the AMBER Project Scientist. Eleven articles will appear this week in Astronomy & Astrophysics' special AMBER section. Three of them describe the unique instrument, while the other eight reveal completely new results about the early and late stages in the life of stars. ESO PR Photo 06b/07 ESO PR Photo 06b/07 The Inner Winds of Eta Carinae The first results presented in this issue cover various fields of stellar and circumstellar physics. Two papers deal with very young solar-like stars, offering new information about the geometry of the surrounding discs and associated outflowing winds. Other articles are devoted to the study of hot active stars of particular interest: Alpha Arae, Kappa Canis Majoris, and CPD -57o2874. They provide new, precise information about their rotating gas envelopes. An important new result concerns the enigmatic object Eta Carinae. Using AMBER with its high spatial and spectral resolution, it was possible to zoom into the very heart of this very massive star. In this innermost region, the observations are dominated by the extremely dense stellar wind that totally obscures the underlying central star. The AMBER observations show that this dense stellar wind is not spherically symmetric, but exhibits a clearly elongated structure. Overall, the AMBER observations confirm that the extremely high mass loss of Eta Carinae's massive central star is non-spherical and much stronger along the poles than in the equatorial plane. This is in agreement with theoretical models that predict such an enhanced polar mass-loss in the case of rapidly rotating stars. ESO PR Photo 06c/07 ESO PR Photo 06c/07 RS Ophiuchi in Outburst Several papers from this special feature focus on the later stages in a star's life. One looks at the binary system Gamma 2 Velorum, which contains the closest example of a star known as a Wolf-Rayet. A single AMBER observation allowed the astronomers to separate the spectra of the two components, offering new insights in the modeling of Wolf-Rayet stars, but made it also possible to measure the separation between the two stars. This led to a new determination of the distance of the system, showing that previous estimates were incorrect. The observations also revealed information on the region where the winds from the two stars collide. The famous binary system RS Ophiuchi, an example of a recurrent nova, was observed just 5 days after it was discovered to be in outburst on 12 February 2006, an event that has been expected for 21 years. AMBER was able to detect the extension of the expanding nova emission. These observations show a complex geometry and kinematics, far from the simple interpretation of a spherical fireball in extension. AMBER has detected a high velocity jet probably perpendicular to the orbital plane of the binary system, and allowed a precise and careful study of the wind and the shockwave coming from the nova. The stream of results from the VLTI and AMBER

  14. space curves and surfaces 1 Plotting Space Curves

    E-print Network

    Verschelde, Jan

    space curves and surfaces 1 Plotting Space Curves the twisted cubic with matplotlib four subplots 2013 Scientific Software (MCS 507 L-16) space curves and surfaces 2 October 2013 1 / 43 #12;space curves and surfaces 1 Plotting Space Curves the twisted cubic with matplotlib four subplots

  15. Weak Curves In Elliptic Curve Cryptography Peter Novotney

    E-print Network

    Stein, William

    Weak Curves In Elliptic Curve Cryptography Peter Novotney March 2010 Abstract Certain choices of elliptic curves and/or underlying fields reduce the security of an elliptical curve cryptosystem of an elliptical curve that reduce the security in this manner, as well as a discussion of the attacks that cause

  16. GENERALIZED MORDELL CURVES, GENERALIZED FERMAT CURVES, AND THE HASSE PRINCIPLE

    E-print Network

    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 Acknowledgements 45 References 45 Abstract. A generalized Mordell

  17. 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.

  18. From the Cover: Hysteresis drives cell-cycle transitions in Xenopus laevis egg extracts

    NASA Astrophysics Data System (ADS)

    Sha, Wei; Moore, Jonathan; Chen, Katherine; Lassaletta, Antonio D.; Yi, Chung-Seon; Tyson, John J.; Sible, Jill C.

    2003-02-01

    Cells progressing through the cell cycle must commit irreversibly to mitosis without slipping back to interphase before properly segregating their chromosomes. A mathematical model of cell-cycle progression in cell-free egg extracts from frog predicts that irreversible transitions into and out of mitosis are driven by hysteresis in the molecular control system. Hysteresis refers to toggle-like switching behavior in a dynamical system. In the mathematical model, the toggle switch is created by positive feedback in the phosphorylation reactions controlling the activity of Cdc2, a protein kinase bound to its regulatory subunit, cyclin B. To determine whether hysteresis underlies entry into and exit from mitosis in cell-free egg extracts, we tested three predictions of the Novak-Tyson model. (i) The minimal concentration of cyclin B necessary to drive an interphase extract into mitosis is distinctly higher than the minimal concentration necessary to hold a mitotic extract in mitosis, evidence for hysteresis. (ii) Unreplicated DNA elevates the cyclin threshold for Cdc2 activation, indication that checkpoints operate by enlarging the hysteresis loop. (iii) A dramatic "slowing down" in the rate of Cdc2 activation is detected at concentrations of cyclin B marginally above the activation threshold. All three predictions were validated. These observations confirm hysteresis as the driving force for cell-cycle transitions into and out of mitosis.

  19. Modeling of hysteresis by means of a directional approach & G. Chagnon(1)

    E-print Network

    Paris-Sud XI, Université de

    silicone rubber and results show that the model predictions and experimental curves fit well. 1 the physical properties of the material, silicone rubbers are classically filled by mineral fillers, implying INTRODUCTION The characterization and modeling of rubber-like ma- terials behavior have been widely addressed

  20. 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.

  1. The Stackel systems and algebraic curves

    Microsoft Academic Search

    A. V. Tsiganov

    1997-01-01

    We show how the Abel-Jacobi map provides all the principal properties of an ample family of integrable mechanical systems associated to hyperelliptic curves. We prove that derivative of the Abel-Jacobi map is just the St\\\\\\

  2. Another Hilbert Curve Generator

    NSDL National Science Digital Library

    Students work step-by-step through the generation of a different Hilbert-like Curve (a fractal made from deforming a line by bending it), allowing them to explore number patterns in sequences and geometric properties of fractals.

  3. Logistic Curve Demo

    NSDL National Science Digital Library

    Roberts, Lila F.

    2002-02-03

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

  4. An Improved Technique for dry Soil Moisture Release Curves to Determine Soil Mineralogical and Physical Properties

    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.

  5. The Bell Curve

    NSDL National Science Digital Library

    2011-05-23

    This lesson is designed to introduce students to the normal distribution or bell curve. The lesson also discusses controversy behind the interpretation of the bell curve. This lesson provides links to discussions and activities related to the normal distribution as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one.

  6. Development of a Portable Mechanical Hysteresis Measurement and Imaging System for Impact Characterization in Honeycomb Sandwich Structures

    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.

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

    SciTech Connect

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

    2011-06-23

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

  8. 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.

  9. Molecular dynamics simulations of the melting curves and nucleation of nickel under pressure

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Jin; Liu, Zhong-Li; Peng, Yu-Feng

    2014-09-01

    Three embedded atom method potentials have been applied to investigate the melting properties of nickel under compression. In these three potentials, Mendelev's potential can reproduce a satisfying melting curve, which accords well with the experiments and first-principles calculations. Thus, we recommend that the Mendelev's potential should be a reliable potential for simulating melting properties of nickel. Using Mendelev's potential, we calculated the melting of Ni with two approaches, i.e., hysteresis approach and two-phase method. Both approaches produce results in very close proximity, with the disagreement less than 4.35% at the applied pressures. Fitting the well-known Simon equation to our melting data yields the melting curves for Ni: 1651(1+P/35.172)0.607 (hysteresis approach) and 1725(1+P/39.812)0.617 (two-phase approach). Based on the hysteresis method, we investigated in detail the melting nucleation of nickel at high pressure, and found that with pressure increasing, the critical nucleus size r* increases fast first and then decreases, and again rises. When taking account of the Gibbs free energy barrier ?G*, it found that the ?G* increase monotonically with pressure up to 300 GPa, and can be described as a third-order polynomial relation.

  10. "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.

  11. Determination of PRT Hysteresis in the Temperature Range from -50 °C to 300 °C

    NASA Astrophysics Data System (ADS)

    Žužek, V.; Batagelj, V.; Bojkovski, J.

    2010-09-01

    This paper discusses the contribution of hysteresis to the measurement uncertainty of industrial platinum resistance thermometers (IPRTs). Hysteresis is one of the sources of uncertainty that has so far not been sufficiently researched and documented. The term hysteresis applies to any system that is path dependent; the output depends on the history of the input. In our case, thermal hysteresis results in different resistance values at the same temperature point, depending on whether the temperature was increasing or decreasing. The reason for such behavior is related to the construction of the thermometer (strain due to thermal expansion and contraction) and also to possible moisture inside the encapsulation. In the process of evaluation of the calibration and measurement capabilities (CMCs) of IPRTs within Working Group 8, the Consultative Committee for Thermometry (CCT WG8) concluded that the uncertainty due to hysteresis is not uniformly defined and not always added to the total uncertainty of the resistance thermometer under calibration. In order to estimate the uncertainty contribution due to the hysteresis and compare different procedures, resistance measurements were carried out on a number of IPRTs of different qualities and tolerance classes. The temperature span was between -50 °C and 300 °C, which is the most frequent temperature range in the practical use of IPRTs. The hysteresis was then determined in different ways (change of resistance at the ice point and at the midpoint temperature according to the ASTM International Standard E644 and according to the new version of IEC Standard 60751), and a comparison of results was made.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  13. Extinction curves expected in young galaxies

    E-print Network

    Hiroyuki Hirashita; Takaya Nozawa; Takashi Kozasa; Takako T. Ishii; Tsutomu T. Takeuchi

    2005-01-10

    We investigate the extinction curves of young galaxies in which dust is supplied from Type II supernovae (SNe II) and/or pair instability supernovae (PISNe). We adopt Nozawa et al. (2003) for compositions and size distribution of grains formed in SNe II and PISNe. We find that the extinction curve is quite sensitive to internal metal mixing in supernovae (SNe). The extinction curves predicted from the mixed SNe are dominated by SiO2 and is characterised by steep rise from infrared to ultraviolet (UV). The dust from unmixed SNe shows shallower extinction curve, because of the contribution from large-sized (~ 0.1 um) Si grains. However, the progenitor mass is important in unmixed SNe II: If the progenitor mass is smaller than ~ 20 Msun, the extinction curve is flat in UV; otherwise, the extinction curve rises toward the short wavelength. The extinction curve observed in a high-redshift quasar (z=6.2) favours the dust production by unmixed SNe II. We also provide some useful observational quantities, so that our model might be compared with future high-z extinction curves.

  14. POINT COMPRESSION FOR KOBLITZ ELLIPTIC CURVES P. N. J. EAGLE, STEVEN D. GALBRAITH, AND J. ONG

    E-print Network

    Abstract. Elliptic curves over finite fields have applications in public key cryptography. A Koblitz curve of elliptic curve cryptography. Wiener and Zuccherato and Gallant, Lambert and Vanstone showed that one can bandwidth for a given security level. Keywords: Elliptic curve cryptography, Koblitz curves, point

  15. Current hysteresis by oxygen vacancy exchange between oxides in Pt/a-IGZO/TaOx/W

    NASA Astrophysics Data System (ADS)

    Kwon, Hyeon-Min; Kim, Myeong-Ho; Lee, Seung-Ryul; Kim, Young-Bae; Choi, Duck-Kyun

    2014-02-01

    ReRAM (resistance random access memory) has been receiving attention as the next-generation memory owing to advantages such as fast switching-speed, low power consumption, and simple structure. However, in order to improve the properties of the candidate materials that show resistive switching phenomenon, it is essential to understand the resistive switching mechanism. This study was conducted to investigate the switching mechanism of a ReRAM device with Pt/a-IGZO (amorphous In-Ga-Zn-O)/TaOx/Al2O3/W structure that exhibits useful properties such as forming free and self-rectifying properties in addition to the general memory properties of existing ReRAM devices. Based on a series of designed experiments and analysis, it was found that the current hysteresis in this device is based on the oxygen vacancy exchange between a-IGZO and TaOx. The movement of positively charged oxygen vacancy according to the relative polarity of applied voltage between the two oxides induces the resistance change of TaOx layer, which in turn results in the resistive switching.

  16. Electric field effect modulation and hysteresis in thin graphite using ferroelectric gate oxides

    NASA Astrophysics Data System (ADS)

    Hong, X.; Zou, K.; Zhu, J.; Posadas, A.; Reiner, J.; Ahn, C. H.

    2008-03-01

    We study the electronic properties of thin graphite field effect transistors (FETs) using ferroelectric gate oxide Pb (Zr,Ti)O3 (PZT). Thin graphite flakes (3-5nm) are exfoliated onto 300 nm PZT films epitaxially grown on doped SrTiO3 (STO) and fabricated into FET devices. Carriers are induced into the FETs by applying a voltage Vg on the STO substrate (backgate). We observe a maximum carrier density (n) of ˜4x10^13cm-2 and a density modulation of ˜2x^12cm-2/Vg(V), and extract a high dielectric constant ˜100 of PZT. We also explore the potential of non-volatile memory devices based on the large polarization of PZT (˜40 ?C/cm^2) and its field switching behavior. At 300 K, both the resistance and n of the devices show pronounced hysteretic behavior as Vg is swept beyond 3 V, with two distinct states. The unstable one decays exponentially with time, with a time constant of ˜6 hours at 300 K and a few days at 150 K, suggesting a thermally activated process. We discuss possible origins of the hysteresis, highlighting the importance of adsorbates at the interface of PZT and graphite.

  17. Hysteresis compensation for piezoelectric actuators in single-point diamond turning

    NASA Astrophysics Data System (ADS)

    Wang, Haifeng; Hu, Dejin; Wan, Daping; Liu, Hongbin

    2006-02-01

    In recent years, interests have been growing for fast tool servo (FTS) systems to increase the capability of existing single-point diamond turning machines. Although piezoelectric actuator is the most universal base of FTS system due to its high stiffness, accuracy and bandwidth, nonlinearity in piezoceramics limits both the static and dynamic performance of piezoelectric-actuated control systems evidently. To compensate the nonlinear hysteresis behavior of piezoelectric actuators, a hybrid model coupled with Preisach model and feedforward neural network (FNN) has been described. Since the training of FNN does not require a special calibration sequence, it is possible for on-line identification and real-time implementation with general operating data of a specific piezoelectric actuator. To describe the rate dependent behavior of piezoelectric actuators, a hybrid dynamic model was developed to predict the response of piezoelectric actuators in a wider range of input frequency. Experimental results show that a maximal error of less than 3% was accomplished by this dynamic model.

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

    PubMed

    Fauchald, Per

    2010-08-01

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

  19. 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.

  20. Numerical study of drop motion on a surface with stepwise wettability gradient and contact angle hysteresis

    NASA Astrophysics Data System (ADS)

    Huang, Jun-Jie; Huang, Haibo; Wang, Xinzhu

    2014-06-01

    In this work, the motion of a two-dimensional drop on a surface with stepwise wettability gradient (WG) is studied numerically by a hybrid lattice-Boltzmann finite-difference method. We incorporate the geometric wetting boundary condition that allows accurate implementation of a contact angle hysteresis (CAH) model. The method is first validated through a series of tests that check different constituents of the numerical model. Then, simulations of a drop on a wall with given stepwise WG are performed under different conditions. The effects of the Reynolds number, the viscosity ratio, the WG, as well as the CAH on the drop motion are investigated in detail. It was discovered that the shape of the drop in steady motion may be fitted by two arcs that give two apparent contact angles, which are related to the respective contact line velocities and the relevant contact angles (that specify the WG and CAH) through the relation derived by Cox ["The dynamics of the spreading of liquids on a solid surface. Part 1. viscous flow," J. Fluid Mech. 168, 169-194 (1986)] if the slip length in simulation is defined according to Yue et al. ["Sharp-interface limit of the Cahn-Hilliard model for moving contact lines," J. Fluid Mech. 645, 279-294 (2010)]. It was also found that the steady capillary number of the drop is significantly affected by the viscosity ratio, the magnitudes of the WG, and the CAH, whereas it almost shows no dependence on the Reynolds number.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  2. Tradeoff analysis of FPGA based elliptic curve cryptography

    Microsoft Academic Search

    Marcus Bednara; M. Daldrup; Jürgen Teich; Joachim Von Zur Gathen; Jamshid Shokrollahi

    2002-01-01

    FPGAs are an attractive platform for elliptic curve cryptography hardware. Since field multiplication is the most critical operation in elliptic curve cryptography, we have studied how efficient sev- eral field multipliers can be mapped to lookup table based FPGAs. Furthermore we have compared different curve coordinate repre- sentations with respect to the number of required field operations, and show how

  3. Observing the yield curve of compacted pack ice

    Microsoft Academic Search

    Keguang Wang

    2007-01-01

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

  4. Changes in Wetting Hysteresis During Bioremediation: Changes in fluid flow behavior monitored with low-frequency seismic attenuation

    Microsoft Academic Search

    W. Wempe; H. Spetzler; C. Kittleson; J. Pursley

    2003-01-01

    We observed significant reduction in wetting hysteresis with time while a diesel-contaminated quartz crystal was dipped in and out of an oil-reducing bacteria solution. This wetting hysteresis is significantly greater than the wetting hysteresis when the diesel-contaminated quartz crystal is dipped in and out of (1) water, (2) diesel and (3) the bacterial food solution that does not contain bacteria.

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

    Microsoft Academic Search

    Tao Huang; John G. Duman

    2002-01-01

    The gene for a thermal hysteresis (antifreeze) protein (sthp-64) from the bittersweet nightshade, Solanum dulcamara, was cloned and characterized. An expression cDNA library prepared from November S. dulcamara was screened using a polyclonal antibody generated against a previously purified 67 kDa thermal hysteresis protein, and positive clones were identified and sequenced. The full-length thermal hysteresis protein gene was cloned into an Escherichia

  6. Neck curve polynomials in neck rupture model

    SciTech Connect

    Kurniadi, Rizal; Perkasa, Yudha S.; Waris, Abdul [Nuclear Physics and Biophysics Research Division, Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung 40132 (Indonesia)

    2012-06-06

    The Neck Rupture Model is a model that explains the scission process which has smallest radius in liquid drop at certain position. Old fashion of rupture position is determined randomly so that has been called as Random Neck Rupture Model (RNRM). The neck curve polynomials have been employed in the Neck Rupture Model for calculation the fission yield of neutron induced fission reaction of {sup 280}X{sub 90} with changing of order of polynomials as well as temperature. The neck curve polynomials approximation shows the important effects in shaping of fission yield curve.

  7. Effect of lipids on sorption/desorption hysteresis in natural organic matter.

    PubMed

    Ding, Guangwei; Rice, James A

    2011-07-01

    The chemical composition and physical conformation of natural organic matter (NOM) play a major role in regulating its capacity to retain hydrophobic organic compounds. Naphthalene and phenanthrene were used to study the correlations between sorption/desorption isotherm nonlinearity and compositional data obtained from quantitative (13)C solid-state DPMAS NMR spectroscopy for soil and peat organic matter with or without lipids. Sorption experiments were conducted using a batch equilibration method. Desorption experiments were carried out immediately following the sorption experiments by three successive decant-refill cycles. Hysteresis was observed in all samples. Nonlinear sorption behavior was increased by removal of lipids from the NOM. The hysteresis index, obtained from the ratio of the Freundlich exponents (N values) for the desorption and sorption isotherms, was lower in the lipid-extracted NOM samples than in the same samples without lipid extraction. The relationship between the extent of hysteresis and the characteristics of the (13)C DPMAS NMR spectra indicates that altering NOM composition through lipid extraction not only increased the proportion of aromatic-C content, but also increased sorption/desorption hysteresis. Our data also suggest that the hysteresis index is negatively related to aromaticity. PMID:21458839

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

    SciTech Connect

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

    1992-05-01

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

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

    SciTech Connect

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

    1992-01-01

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

  10. Angular-dependent remanent magnetization curve for perpendicular magnetic recording media determined by precise polar-Kerr detection system

    NASA Astrophysics Data System (ADS)

    Hasegawa, D.; Saito, S.; Itagaki, N.; Meguro, S.; Konishi, Y.; Yanagisawa, E.; Akahane, K.; Takahashi, M.

    We developed the polar-Kerr detection system and evaluated the angular dependence of magnetization curves with applied field of various directions during the newly developed system. The polar-Kerr detection system enabled precise evaluation of angular dependence of remanent coercivity ( Hcr), as compared with the conventional VSM system. In addition, a cusp appeared in polar-Kerr hysteresis loop was observed to originate magnetization reversal by the thermal agitation.

  11. Complementary curves of descent

    NASA Astrophysics Data System (ADS)

    Mungan, Carl E.; Lipscombe, Trevor C.

    2013-01-01

    The shapes of two wires in a vertical plane with the same starting and ending points are described as complementary curves of descent if beads frictionlessly slide down both of them in the same time, starting from rest. Every analytic curve has a unique complement, except for a cycloid (solution of the brachistochrone problem), which is self complementary. A striking example is a straight wire whose complement is a lemniscate of Bernoulli. Alternatively, the wires can be tracks down which round objects undergo a rolling race. The level of presentation is appropriate for an intermediate undergraduate course in classical mechanics.

  12. Exploring Area between Curves

    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.

  13. New Curves from Branes

    E-print Network

    Landsteiner, K; Landsteiner, Karl; Lopez, Esperanza

    1998-01-01

    We consider configurations of Neveu-Schwarz fivebranes, Dirichlet fourbranes and an orientifold sixplane in type IIA string theory. Upon lifting the configuration to M-theory and proposing a description of how to include the effects of the orientifold sixplane we derive the curves describing the Coulomb branch of N=2 gauge theories with orthogonal and symplectic gauge groups, product gauge groups of the form SU(k_1)...SU(k_i) x SO(N) and SU(k_1)...SU(k_i) x Sp(N). We also propose new curves describing theories with unitary gauge groups and matter in the symmetric or antisymmetric representation.

  14. New Curves from Branes

    E-print Network

    Karl Landsteiner; Esperanza Lopez

    1997-08-22

    We consider configurations of Neveu-Schwarz fivebranes, Dirichlet fourbranes and an orientifold sixplane in type IIA string theory. Upon lifting the configuration to M-theory and proposing a description of how to include the effects of the orientifold sixplane we derive the curves describing the Coulomb branch of N=2 gauge theories with orthogonal and symplectic gauge groups, product gauge groups of the form SU(k_1)...SU(k_i) x SO(N) and SU(k_1)...SU(k_i) x Sp(N). We also propose new curves describing theories with unitary gauge groups and matter in the symmetric or antisymmetric representation.

  15. 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.

  16. Anomalous optical switching and thermal hysteresis behaviors of VO2 films on glass substrate

    NASA Astrophysics Data System (ADS)

    Li, Jian; Dho, Joonghoe

    2011-12-01

    In order to study the optical switching of vanadium dioxide (VO2) and its thermal hysteresis behavior, we fabricated VO2 films on glass substrates at various oxygen pressures. Only the VO2 films made at 5-10 mTorr displayed x-ray diffraction peaks and metal-insulator transition. Upon heating and cooling, remarkably, these samples exhibited significant optical switching behaviors with a clockwise thermal hysteresis in the infrared range of >850 nm or with a counterclockwise thermal hysteresis in the near visible range of 650-850 nm. The temperature dependence of optical absorption was explained by the O2p-V3d splitting depending on the structural transition of VO2.

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

    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.

  18. Modeling biaxial stress effects on magnetic hysteresis in steel with the field and stress axes noncoaxial

    NASA Astrophysics Data System (ADS)

    Sablik, M. J.; Augustyniak, B.; Chmielewski, M.

    1999-04-01

    A model based on the domain wall pinning magnetomechanical hysteresis model of Sablik and Jiles [M. J. Sablik and D. C. Jiles, IEEE Trans. Magn. 29, 2113 (1993)] was formulated to compute changes in magnetic hysteresis under biaxial stress conditions with the magnetic field and stress axes noncoaxial. The model included the Villari effect and other asymmetric stress effects. The magnetic field was taken at various angles relative to the stress axis. The Barkhausen noise, hysteresis loss, and maximum flux density were computed for fields varying between ±1 kA/m. The results compared favorably to experimental data on several steels—Polish St3 steel, Polish St41 steel, and US commercial grade steel pipe.

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

    NASA Astrophysics Data System (ADS)

    Tamion, Alexandre; Bonet, Edgar; Tournus, Florent; Raufast, Cécile; Hillion, Arnaud; Gaier, Oksana; Dupuis, Véronique

    2012-04-01

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

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

    SciTech Connect

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

    2008-10-14

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

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

    PubMed

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

    2011-03-01

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

  2. Curved nanostructured materials

    Microsoft Academic Search

    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

  3. The Bacterial Growth Curve.

    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)

  4. Statistical Decline Curve Analysis

    Microsoft Academic Search

    Robert McNulty; Roy Knapp

    1981-01-01

    The best hyberbolic curve is numerically fit to production decline data from selected oil wells. A non-linear optimization computer program finds the three best values of the general hyperbolic parameters using least squares regression. By using weighted residuals better history matching is obtained than with previous least squares methods. The future rate-time behavior of a well with only a few

  5. Elliptic Curve Cryptography Engineering

    Microsoft Academic Search

    ALESSANDRO CILARDO; LUIGI COPPOLINO; NICOLA MAZZOCCA; LUIGI ROMANO

    2006-01-01

    In recent years, elliptic curve cryptography (ECC) has gained widespread exposure and acceptance, and has already been included in many security standards. Engineering of ECC is a complex, interdisciplinary research field encompassing such fields as mathematics, computer science, and electrical engineering. In this paper, we survey ECC implementation issues as a prominent case study for the relatively new discipline of

  6. Extinction curves in AGN

    E-print Network

    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.

  7. 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.

  8. Characteristic Curves of PEMFC

    NSDL National Science Digital Library

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

  9. New Curves from Branes

    Microsoft Academic Search

    Karl Landsteiner; Esperanza Lopez

    We consider configurations of Neveu-Schwarz fivebranes, Dirichlet fourbranes and an orientifold sixplane in type IIA string theory. Upon lifting the configuration to M-theory and proposing a description of how to include the effects of the orientifold sixplane we derive the curves describing the Coulomb branch of N = 2 gauge theories with orthogonal and symplectic gauge groups, product gauge groups

  10. New curves from branes

    Microsoft Academic Search

    Karl Landsteiner; Esperanza Lopez

    1998-01-01

    We consider configurations of Neveu-Schwarz fivebranes, Dirichlet fourbranes and an orientifold sixplane in type IIA string theory. Upon lifting the configuration to M-theory and proposing a description of how to include the effects of the orientifold sixplane we derive the curves describing the Coulomb branch of N = 2 gauge theories with orthogonal and symplectic gauge groups, product gauge groups

  11. Vegetable Light Curves

    NSDL National Science Digital Library

    2009-04-22

    In this activity, students will observe the surface of rotating potatoes to help them understand how astronomers can sometimes determine the shape of asteroids from variations in reflective brightness. When astronomers graph data relating to reflective brightness as a function of time, the resulting graph is called a "light curve."

  12. Graphing Polar Curves

    ERIC Educational Resources Information Center

    Lawes, Jonathan F.

    2013-01-01

    Graphing polar curves typically involves a combination of three traditional techniques, all of which can be time-consuming and tedious. However, an alternative method--graphing the polar function on a rectangular plane--simplifies graphing, increases student understanding of the polar coordinate system, and reinforces graphing techniques learned…

  13. Simultaneous Arithmetic Progressions on Algebraic Curves

    E-print Network

    Schwartz, Ryan; de Zeeuw, Frank

    2009-01-01

    A simultaneous arithmetic progression (s.a.p.) of length k consists of k points (x_i, y_\\sigma(i)), where x_i and y_i are arithmetic progressions and \\sigma is a permutation. Garcia-Selfa and Tornero asked whether there is a bound on the length of an s.a.p. on an elliptic curve in Weierstrass form over Q. We show that 4319 is such a bound for curves over R. This is done by considering translates of the curve in a grid as a graph. A simple upper bound is found for the number of crossings and the 'crossing inequality' gives a lower bound. Together these bound the length of an s.a.p. on the curve. We then use a similar method to extend the result to arbitrary real algebraic curves. Instead of considering s.a.p.'s we consider k^2/3 points in a grid. The number of crossings is bounded by Bezout's Theorem. We then give another proof using a result of Jarnik bounding the number of grid points on a convex curve. This result applies as any real algebraic curve can be broken up into convex and concave parts, the number...

  14. ‘Universal’ recession curves and their geomorphological interpretation

    NASA Astrophysics Data System (ADS)

    Biswal, Basudev; Marani, Marco

    2014-03-01

    The study of recession flows offers fundamental insights into basin hydrological processes and, in particular, into the collective behavior of the governing dominant subsurface flows and properties. We use here an existing geomorphological interpretation of recession dynamics, which links the exponent in the classic recession curve -dQ/dt=kQ? to the geometric properties of the time-varying drainage network to study the general properties of recession curves across a wide variety of river basins. In particular, we show how the parameter k depends on the initial soil moisture state of the basin and can be made to explicitly depend on an index discharge, representative of initial sub-subsurface storage. Through this framework we obtain a non-dimensional, event-independent, recession curve. We subsequently quantify the variability of k across different basins on the basis of their geometry, and, by rescaling, collapse curves from different events and basins to obtain a generalized, or ‘universal’, recession curve. Finally, we analyze the resulting normalized recession curves and explain their universal characteristics, lending further support to the notion that the statistical properties of observed recession curves bear the signature of the geomorphological structure of the networks producing them.

  15. Three-body choreographies in given curves

    NASA Astrophysics Data System (ADS)

    Ozaki, Hiroshi; Fukuda, Hiroshi; Fujiwara, Toshiaki

    2009-10-01

    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 determine the motion of the planet completely. Even in the three-body problem, in some cases, the shape of the orbit, conservation of the center of mass and a constant of motion (the angular momentum or the total energy) determine 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 the 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 do not have point symmetry. Each body may have its own curve and its own non-vanishing masses.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  17. Curved microchannels and bacterial streamers

    NASA Astrophysics Data System (ADS)

    Rusconi, Roberto; Lecuyer, Sigolene; Guglielmini, Laura; Stone, Howard

    2010-03-01

    Bacterial biofilms are commonly identified as microbial communities attached to a surface and encased in a self-secreted extracellular matrix. Due to their increased resistance to antimicrobial agents, biofilms have an enormous impact on health and medicine (e.g., wound healing, implant-associated infections, disease transmission). On the other hand, they constitute a major component of the stream ecosystem by increasing transport of nutrients and retention of suspended particles. In this talk, we present an experimental study of bacterial biofilm development in a microfluidic device. In particular, we show the formation of filamentous structures, or streamers, in curved channels and how these suspended biofilms are linked to the underlying hydrodynamics.

  18. A neural model of hysteresis in amorphous materials and piezoelectric materials

    NASA Astrophysics Data System (ADS)

    Ma, Lianwei; Shen, Yu

    2014-08-01

    A new approach to constructing hysteretic operator (HO) is proposed in this paper. Based on the HO, the input space of neural networks is expanded from one-dimension to two-dimension and the multi-value mapping of hysteresis is transformed into a continuous mapping comprised of one-to-one mapping and multiple-to-one mapping. Based on the expanded input space, a neural network is employed to approximate hysteresis. The results of experimental examples suggest the proposed approach is effective.

  19. Effect of twist process on critical current and hysteresis loss of Nb 3Sn strands

    NASA Astrophysics Data System (ADS)

    Zhang, P. X.; Zhou, L.; Tang, X. D.; Liang, M.; Li, C. G.; Wu, Y.; Yan, G.; Yang, M.; Feng, Y.; Liu, X. H.; Weng, P. D.; Lu, Y. F.

    2007-10-01

    We have prepared Nb 3Sn strands by the internal tin process for superconducting conductor application in the international thermonuclear experimental reactor (ITER). The multifilamentary Nb 3Sn strands have a diameter of 0.82 mm and a unit length longer than 5000 m. We have investigated the effect of twist process on superconducting critical current density and hysteresis loss for Nb 3Sn strands. It has been found that the twist process significantly reduces the hysteresis loss of the strands, while the critical current density and the n-value remain nearly unchanged.

  20. Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO2: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J-V Hysteresis.

    PubMed

    O'Regan, Brian C; Barnes, Piers R F; Li, Xiaoe; Law, Chunhung; Palomares, Emilio; Marin-Beloqui, Jose M

    2015-04-22

    Methylammonium lead iodide (MAPI) cells of the design FTO/sTiO2/mpTiO2/MAPI/Spiro-OMeTAD/Au, where FTO is fluorine-doped tin oxide, sTiO2 indicates solid-TiO2, and mpTiO2 is mesoporous TiO2, are studied using transient photovoltage (TPV), differential capacitance, charge extraction, current interrupt, and chronophotoamperometry. We show that in mpTiO2/MAPI cells there are two kinds of extractable charge stored under operation: a capacitive electronic charge (?0.2 ?C/cm(2)) and another, larger charge (40 ?C/cm(2)), possibly related to mobile ions. Transient photovoltage decays are strongly double exponential with two time constants that differ by a factor of ?5, independent of bias light intensity. The fast decay (?1 ?s at 1 sun) is assigned to the predominant charge recombination pathway in the cell. We examine and reject the possibility that the fast decay is due to ferroelectric relaxation or to the bulk photovoltaic effect. Like many MAPI solar cells, the studied cells show significant J-V hysteresis. Capacitance vs open circuit voltage (Voc) data indicate that the hysteresis involves a change in internal potential gradients, likely a shift in band offset at the TiO2/MAPI interface. The TPV results show that the Voc hysteresis is not due to a change in recombination rate constant. Calculation of recombination flux at Voc suggests that the hysteresis is also not due to an increase in charge separation efficiency and that charge generation is not a function of applied bias. We also show that the J-V hysteresis is not a light driven effect but is caused by exposure to electrical bias, light or dark. PMID:25785843

  1. Central Rotation Curves of Spiral Galaxies

    E-print Network

    Y. Sofue; Y. Tutui; M. Honma; A. Tomita; T. Takamiya; J. Koda; Y. Takeda

    1999-05-06

    We present high-resolution central-to-outer rotation curves for Sb, SBb, Sc, and SBc galaxies. We discuss their general characteristics, particularly their central behavior, as well as dependencies on morphological types, activity, and peculiarity. The rotation curves generally show a steep nuclear rise, and high-velocity central rotation, followed by a broad maximum in the disk and then by a flat rotation due to the massive halo. Since the central high velocity and steep rise are common to all massive galaxies, it cannot be due to non-circular motions. Disk rotation curves of barred galaxies show larger dispersion than those of normal galaxies which is probably due to non-circular motions. Interacting galaxies show often perturbed outer rotation curves, while their central rotation shows no particular peculiarity. Also, central activities, such as starbursts and AGN, appear to show no particular correlation with the property of rotation curves. This would suggest that the central activities are triggered by a more local effect than the global dynamical property.

  2. Hysteresis effects in x-irradiated KH2PO4, KD2PO4, and RbH2PO4 ferroelectric single crystals observed with electron-spin resonance

    NASA Astrophysics Data System (ADS)

    Truesdale, Roger D.; Farach, Horacio A.; Poole, Charles P., Jr.

    1980-07-01

    Hysteresis curves were plotted from the ESR spectra of selected x-irradiated potassium dihydrogen phosphate (KDP) type ferroelectric single crystals. The data for the loops were obtained by measuring the difference in intensity of appropriate lines in the ESR spectra of the radicals formed by x irradiation in KH2PO4, KD2PO4, and RbH2PO4. Coercive field values at 90 K varied from 8 to kV/cm. These results are compared to coercive field values reported by other workers for x-irradiated KH2PO4 doped with selenium and arsenic ions.

  3. Hysteresis-free high-temperature precise bimorph actuators produced by direct bonding of lithium niobate wafers

    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.

  4. Thin-film photoconductor-electroluminescent memory device with a high brightness and a wide and stable hysteresis

    NASA Astrophysics Data System (ADS)

    Thioulouse, P.; Gonzalez, C.; Solomon, I.

    1987-04-01

    An improved thin-film photoconductor-electroluminescent memory and display device is described, which integrates an optimized ZnS:Mn active layer, Ta2O5 insulating films, and a-Si(1-x)C(x):H photoconducting material. The performance with a 1-kHz sinewave excitation is an hysteresis width of about 25 V, on ON luminance of about 650 cd/sq m, and an OFF luminance of about 0.1 cd/sq m. The memory effect shows no degradation over an estimated operating time of 2000 h. The electrical ON switching time is shorter than 10 microsec. The performance of a full-size panel based on this structure is briefly discussed.

  5. Super-mercuryphobic and hydrophobic diamond surfaces with hierarchical structures: Vanishment of the contact angle hysteresis with mercury

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    PubMed Central

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

    2012-01-01

    Abrupt climate transitions, known as Dansgaard-Oeschger and Heinrich events, occurred frequently during the last glacial period, specifically from 80–11 thousand years before present, but were nearly absent during interglacial periods and the early stages of glacial periods, when major ice-sheets were still forming. Here we show, with a fully coupled state-of-the-art climate model, that closing the Bering Strait and preventing its throughflow between the Pacific and Arctic Oceans during the glacial period can lead to the emergence of stronger hysteresis behavior of the ocean conveyor belt circulation to create conditions that are conducive to triggering abrupt climate transitions. Hence, it is argued that even for greenhouse warming, abrupt climate transitions similar to those in the last glacial time are unlikely to occur as the Bering Strait remains open. PMID:22493225

  8. A method for affine invariant curve smoothing

    NASA Astrophysics Data System (ADS)

    Nishida, Takahiro; Toriu, Takashi

    2014-01-01

    This paper proposes a new curve smoothing method invariant to affine transformation. Curve smoothing is one of the important challenges in computer vision as a procedure for noise suppression in shape analysis such as Curvature Scale Space (CSS). Currently, Gaussian filtering is widely used among a lot of smoothing methods. However Gaussian filtering is not affine invariant. This paper proposes a new method for curve smoothing that is invariant under affine transformation such that area of any region in the image does not change. Specifically, we introduce an affine invariant evaluate function with a metric tensor. The original curve is smoothed by minimizing the evaluation function. We mathematically prove that this method is affine invariant. Further, experimental results show that the proposed method is almost never affected by affine transformation different from usual Gaussian filtering. In the proposed method, processing results are expected to be not affected much by variation of the viewpoint.

  9. Stress dependence and effect of plastic deformation on magnetic hysteresis and anhysteretic magnetization of FeNi32% films

    Microsoft Academic Search

    P. Finkel; S. Lofland

    2007-01-01

    The magnetic hysteresis and anhysteretic magnetization of FeNi32% films were investigated as a function of isotropic stress. The magnetostriction contribution to dc magnetization under elastic stress and the effect of the plastic strain on the hysteresis loops are discussed. Also, a role of the plastic deformation interrelated with the elastic stress in the magnetization process is established. An experimental system

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  11. A time-based double-band hysteresis current regulation strategy for single-phase multilevel inverters

    Microsoft Academic Search

    Poh Chiang Loh; Gerwich H. Bode; Donald Grahame Holmes; Thomas A. Lipo

    2003-01-01

    Most multilevel inverter hysteresis current regulators use either multiple hysteresis bands, or a time-based switching logic that forces the current error back to zero by recursively stepping through successive voltage levels. Of these two alternatives, the time-based approach has the merit of only requiring simple analog circuitry and digital logic to implement the voltage level selection process for inverters of

  12. Feedforward controller based-on piezoelectric actuator's hysteresis model and its performance simulation of an XY plane motion stage

    Microsoft Academic Search

    Pan Lizhi; Zhan Min; Wang Wendong; Liang Yakun

    2009-01-01

    The piezoelectric actuator is a perfect nano-positioning drive element for its good performance except its hysteresis, creep, and nonlinearity, which make its control difficult. This paper proposed a control design methodology based on piezoelectric actuator's hysteresis model. First system identifying experiments were performed to identify the system model of a XY serial kinematics plane nanopositioning stage employing piezoelectric actuators. The

  13. Atlas of fatigue curves

    SciTech Connect

    Boyer, H.E.

    1986-01-01

    This Atlas was developed to serve engineers who are looking for fatigue data on a particular metal or alloy. Having these curves compiled in a single book will also facilitate the computerization of the involved data. It is pointed out that plans are under way to make the data in this book available in ASCII files for analysis by computer programs. S-N curves which typify effects of major variables are considered along with low-carbon steels, medium-carbon steels, alloy steels, HSLA steels, high-strength alloy steels, heat-resisting steels, stainless steels, maraging steels, cast irons, and heat-resisting alloys. Attention is also given to aluminum alloys, copper alloys, magnesium alloys, molybdenum, tin alloys, titanium and titanium alloys, zirconium, steel castings, closed-die forgings, powder metallurgy parts, composites, effects of surface treatments, and test results for component parts.

  14. Curved PN triangles

    Microsoft Academic Search

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

    2001-01-01

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

  15. Mouse Curve Biometrics

    SciTech Connect

    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.

  16. Diffusion in Curved Spacetimes

    E-print Network

    Matteo Smerlak

    2011-11-18

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

  17. Uniformizing Tropical Curves I: Genus Zero and One

    E-print Network

    Speyer, David E

    2007-01-01

    In tropical geometry, given a curve in a toric variety, one defines a corresponding graph embedded in Euclidean space. We study the problem of reversing this process for curves of genus zero and one. Our methods focus on describing curves by parameterizations, not by their defining equations; we give parameterizations by rational functions in the genus zero case and by non-archimedean elliptic functions in the genus one case. For genus zero curves, those graphs which can be lifted can be characterized in a completely combinatorial manner. For genus one curves, show that certain conditions identified by Mikhalkin are sufficient and we also identify a new necessary condition.

  18. A pore scale investigation of sorption hysteresis and its application in nano-petrophysics (Invited)

    NASA Astrophysics Data System (ADS)

    Prodanovic, M.; Mehmani, A.

    2013-12-01

    Experimental methods on organic-rich mud rock (shale) samples show a wide distri- bution of pore sizes (1 nm - 1 micron) and suggest complex spatial configurations. In any rock sample, pore sizes and pore connectivity have first-order impact on macroscopic properties such as permeability. We adapted gas flow physics in pore throat networks to nanoscale, specifically relevant to modeling shale reservoirs. Contrary to the classical pore scale flow modeling in conventional reservoirs, where permeability is only a function of topology and morphology of the pores, the permeability in shale depends on pressure as well. In addition to traditional viscous flow of Hagen-Poiseuille or Darcy type, we included slip flow, Knudsen diffusion as well as sorption on pore walls in our network model to simulate gas flow in shale systems that contain pores on both micrometer and nanometer scales. Diffusion and sorption have a significant impact on ultimate gas permeability, and the magnitude of the effect depends on pore connectivity, network geometry and size distribution. A direct observation on shale pore inter-connectivity in three dimensions is limited in length scale and field of view, however, and therefore it is imperative to quantify the pore structure indirectly. We further explore comparison of nitrogen sorption experiments and network simulation for the purpose of shale pore network structure quantification. Motivated by existing two-dimensional scanning electron microscopy images, we construct three network classes with distinct, three-dimensional multiscale types of interconnectivity. We simulate nitrogen sorption cycle hysteresis and helium endpoint relative permeability for each network type. We observe and classify signature behaviors for each type that can be compared to experimental data in order to infer actual 3D shale pore network interconnectivity.

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

    PubMed

    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

  20. Thermodynamic Analysis of Snowball Earth Hysteresis Experiment: Efficiency, Entropy Production, and Irreversibility

    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

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

    PubMed

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

    2014-12-01

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

  2. Rate-dependent elastic hysteresis during the peeling of pressure sensitive adhesives.

    PubMed

    Villey, Richard; Creton, Costantino; Cortet, Pierre-Philippe; Dalbe, Marie-Julie; Jet, Thomas; Saintyves, Baudouin; Santucci, Stéphane; Vanel, Loïc; Yarusso, David J; Ciccotti, Matteo

    2015-04-22

    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

  3. Pattern selection and hysteresis in the Rietkerk model for banded vegetation in semi-arid environments.

    PubMed

    Dagbovie, Ayawoa S; Sherratt, Jonathan A

    2014-10-01

    Banded vegetation is a characteristic feature of semi-arid environments. It occurs on gentle slopes, with alternating stripes of vegetation and bare ground running parallel to the contours. A number of mathematical models have been proposed to investigate the mechanisms underlying these patterns, and how they might be affected by changes in environmental conditions. One of the most widely used models is due to Rietkerk and co-workers, and is based on a water redistribution hypothesis, with the key feedback being that the rate of rainwater infiltration into the soil is an increasing function of plant biomass. Here, for the first time, we present a detailed study of the existence and stability of pattern solutions of the Rietkerk model on slopes, using the software package wavetrain (www.ma.hw.ac.uk/wavetrain). Specifically, we calculate the region of the rainfall-migration speed parameter plane in which patterns exist, and the sub-region in which these patterns are stable as solutions of the model partial differential equations. We then perform a detailed simulation-based study of the way in which patterns evolve when the rainfall parameter is slowly varied. This reveals complex behaviour, with sudden jumps in pattern wavelength, and hysteresis; we show that these jumps occur when the contours of constant pattern wavelength leave the parameter region giving stable patterns. Finally, we extend our results to the case in which a diffusion term for surface water is added to the model equations. The parameter regions for pattern existence and stability are relatively insensitive to small or moderate levels of surface water diffusion, but larger diffusion coefficients significantly change the subdivision into stable and unstable patterns. PMID:25142517

  4. 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.

  5. [LR7573E]059101PRE Contact-angle hysteresis in solid-on-solid wetting

    E-print Network

    Attard, Phil

    PROOF COPY [LR7573E]059101PRE Contact-angle hysteresis in solid-on-solid wetting Phil Attard Ian the solid surfaces. The deformation and contact area are obtained self-consistently as a function of load depend upon the interfacial energies of the phases. For a liquid drop on a solid in a vapor the Young

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

    PubMed Central

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

    2013-01-01

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

  7. Sensitivity of sulfate direct climate forcing to the hysteresis of particle phase transitions

    E-print Network

    , focusing on the sulfate-ammonium system. The phase transition affects the hygroscopic behavior]. The composition of sulfate-ammonium particles is charac- terized by the extent of neutralization, defined as XSensitivity of sulfate direct climate forcing to the hysteresis of particle phase transitions Jun

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

    E-print Network

    Neukirch, Sébastien

    Experiments on Snap Buckling, Hysteresis and Loop Formation in Twisted Rods by V.G.A. Goss, G. In this way, commonly encountered phenomena are investigated, such as snap buckling, the formation of loops, rod experiments, snap buckling, loop formation, snarling, hockling, welded boundary condi- tions

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

    E-print Network

    Neukirch, Sébastien

    Experiments on snap buckling, hysteresis and loop formation in twisted rods. V.G.A.Goss, G encountered phenomena such as snap­buckling, the formation of loops, and buckling into and out of planar, snap buckling, loop formation, snarling, hock­ ling, welded boundary conditions. 1 Introduction

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

    E-print Network

    van der Heijden, Gert

    Experiments on snap buckling, hysteresis and loop formation in twisted rods V.G.A. Goss , G phenomena such as snap buckling, the formation of loops, and buckling into and out of planar configurations are investigated. The effect of gravity is discussed. Key words: twisted rods, rod experiments, snap buckling, loop

  11. Cochlear hysteresis: Observation with low-frequency modulated distortion product otoacoustic emissions

    E-print Network

    Allen, Jont

    Cochlear hysteresis: Observation with low-frequency modulated distortion product otoacoustic of the MPs occurred at positive sound pressures for rising in bias pressure or loading of the cochlear levels. Both physiologic indices and model parameters suggest that the cochlear transducer dynamically

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

    E-print Network

    Martcheva, Maia

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

  13. Hysteresis, Discrete Memory, and Nonlinear Wave Propagation in Rock: A New Paradigm

    Microsoft Academic Search

    R. A. Guyer; K. R. McCall; G. N. Boitnott

    1995-01-01

    The structural elements in a rock are characterized by their density in Preisach-Mayergoyz space (PM space). This density is found for a Berea sandstone from stress-strain data and used to study the response of the sandstone to elaborate pressure protocols. Hysteresis with discrete memory, in agreement with experiment, is found. The relationship between strain, quasistatic modulus, and dynamic modulus is

  14. X-ray diffraction investigation of a spin crossover hysteresis loop. P Guionneau1,

    E-print Network

    Boyer, Edmond

    @icmcb-bordeaux.cnrs.fr The nature and the mechanism of the magnetic hysteresis for the thermal spin crossover exhibited by an iron(II) compound is investigated by mean of variable temperature powder and single crystals X-ray diffraction in the spin crossover features according to the nature of the sample ­ powder or single crystal ­ that should

  15. Simulation of AV hysteresis pacing using an integrated dual chamber heart and pacer model

    Microsoft Academic Search

    Jie Lian; Garth Garner; Hannes Krätschmer; Dirk Müssig

    2009-01-01

    Long term right ventricular apical pacing has been known to have adverse effects in cardiac function. The AV hysteresis (AVH) is a feature existing in many dual-chamber cardiac pacemakers that aims to minimize the right ventricular pacing, but its clinical efficacy remains inconclusive due to conflicting evidence from different studies. We have recently developed a novel integrated dual-chamber heart and

  16. Adaptive wavelet neural network control with hysteresis estimation for piezo-positioning mechanism.

    PubMed

    Lin, Faa-Jeng; Shieh, Hsin-Jang; Huang, Po-Kai

    2006-03-01

    An adaptive wavelet neural network (AWNN) control with hysteresis estimation is proposed in this study to improve the control performance of a piezo-positioning mechanism, which is always severely deteriorated due to hysteresis effect. First, the control system configuration of the piezo-positioning mechanism is introduced. Then, a new hysteretic model by integrating a modified hysteresis friction force function is proposed to represent the dynamics of the overall piezo-positioning mechanism. According to this developed dynamics, an AWNN controller with hysteresis estimation is proposed. In the proposed AWNN controller, a wavelet neural network (WNN) with accurate approximation capability is employed to approximate the part of the unknown function in the proposed dynamics of the piezo-positioning mechanism, and a robust compensator is proposed to confront the lumped uncertainty that comprises the inevitable approximation errors due to finite number of wavelet basis functions and disturbances, optimal parameter vectors, and higher order terms in Taylor series. Moreover, adaptive learning algorithms for the online learning of the parameters of the WNN are derived based on the Lyapunov stability theorem. Finally, the command tracking performance and the robustness to external load disturbance of the proposed AWNN control system are illustrated by some experimental results. PMID:16566470

  17. Calculation of hysteresis losses in hard superconductors carrying ac: isolated conductors and edges of thin sheets

    Microsoft Academic Search

    W T Norris

    1970-01-01

    Two methods of calculating hysteresis losses in hard superconductors are described. The London model is assumed in which the critical current density is taken independent of magnetic field. Losses in isolated wires of different cross section are considered but it is found that losses for solid wires vary by at most a factor of 3 for different shaped wires of

  18. Towards a truck-driver model using a hysteresis based analysis and verification approach

    E-print Network

    Towards a truck-driver model using a hysteresis based analysis and verification approach (Extended this methodology, we reuse a car driver model and build a truck driver model by considering relevant aspects. We. In this work we propose to produce a model of the behav- ior of truck drivers, which are known to have

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

    Microsoft Academic Search

    Peter J. Chen; Stephen T. Montgomery

    1980-01-01

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

  20. Thermodynamic Analysis of Snowball Earth Hysteresis Experiment: Efficiency, Entropy Production, and Irreversibility

    Microsoft Academic Search

    Valerio Lucarini; Klaus Fraedrich; Frank Lunkeit

    2010-01-01

    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

  1. The role of transport phenomena on efficacy, stability and hysteresis in encapsulated cellular systems

    Microsoft Academic Search

    Susan C. Roberts; Robert J. Fisher

    2000-01-01

    Multiple steady states are possible when transport limitations are imposed on cellular systems that exhibit some level of substrate inhibition. These distinct steady states can be achieved under identical operating conditions such as temperature, flowrate, and composition. Cells will exhibit different metabolisms depending on their environmental history and the path taken to the specific reactor operating conditions. Hysteresis is observed

  2. Strain and hysteresis by stochastic matrix cracking in ceramic matrix composites

    Microsoft Academic Search

    B. K. Ahn; W. A. Curtin

    1997-01-01

    A theory is presented to predict the stress\\/strain relations and unload\\/reload hysteresis behavior during the evolution of multiple matrix cracking in unidirectional fiber reinforced ceramic matrix composites (CMCs). The theory is based on the similarity between multiple matrix cracking and fiber fragmentation in a single fiber composite, and determines the crack and strain evolution as a function of the statistical

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

    E-print Network

    Perfect, Ed

    , and the air/water displacement suction), and A2 (a compound parameter that includes D2, and the critical, were significantly affected by hysteresis and/or the sludge treatments for the loam soil. Values of A1 of the loam soil. © 2006 Elsevier B.V. All rights reserved. 1. Introduction Continuous human population growth

  4. Experimental investigation on hysteresis effect of refrigerant flowing through a coiled adiabatic capillary tube

    Microsoft Academic Search

    Zhou Guobing; Zhang Yufeng

    2006-01-01

    This paper experimentally investigates the mass flow rate hysteresis of R22 in a coiled adiabatic capillary tube. The measured mass flow rate data in a coiled adiabatic capillary are found to be more dispersive than those in a straight one. The scatter bands of measured data are significantly dependent on how the state points are achieved. For increasing inlet subcooling

  5. Incorporating core hysteresis properties in three-dimensional computations of transformer inrush current forces

    Microsoft Academic Search

    A. A. Adly; H. H. Hanafy

    2009-01-01

    It is well known that transformer inrush currents depend upon the core properties, residual flux, switching instant, and the overall circuit parameters. Large transient inrush currents introduce abnormal electromagnetic forces which may destroy the transformer windings. This paper presents an approach through which core hysteresis may be incorporated in three-dimensional computations of transformer inrush current forces. Details of the approach,

  6. Hysteresis Loop for a No-loaded, Delta-connected Transformer Model Deduced from Measurements

    NASA Astrophysics Data System (ADS)

    Corrodi, Yves; Kamei, Kenji; Kohyama, Haruhiko; Ito, Hiroki

    At a transformer's steady-state condition, whereby a transformer and its load are constantly supplied by a sinusoidal source, the current-flux pair within the transformer core and its windings will cycle along a hysteresis loop. This nonlinear current-flux characteristic becomes important while at transformer gets reenergized. A remaining residual flux and the fact that a transformer is typically used up to its saturation level can lead to high-amplitude magnetizing inrush currents and associated voltage disturbances. These disturbances can be reduced by controlled transformer switching. In order to pre-evaluate the effect of a specific controlled transformer energization, pre-simulations can be applied. In that case the hysteresis loop and its saturation characteristic will become the most important model parameter. If the corresponding manufacturer specifications are not available a standard hysteresis loops can be used, but might come up with an inaccurate simulation result. Therefore, this paper analyses the measured 3-phase currents from two delta-connected power transformers by “Fourier Series” in order to deduce a single-phase hysteresis loop, which can be implemented into a typical 3-phase transformer model. Additionally, the saturation behavior of a power-transformer will be estimated and a comparison of ATP/EMTP simulations will conclude this paper.

  7. Hysteresis operators in phase-field models of Penrose-fife type

    Microsoft Academic Search

    Pavel Krej?í; Jürgen Sprekels

    1998-01-01

    Phase-field systems as mathematical models for phase transitions have drawn a considerable attention in recent years. However, while they are suitable for capturing many of the experimentally observed phenomena, they are only of restricted value in modelling hysteresis effects occurring during phase transition processes. To overcome this shortcoming of existing phase-field theories, the authors have recently proposed a new approach

  8. Series and parallel operation of hysteresis current-controlled PWM rectifiers

    Microsoft Academic Search

    J. W. Dixon; B. T. Ooi

    1989-01-01

    Different strategies for series and parallel connections of hysteresis current-controlled PWM rectifier have been investigated by experiments, computer simulations, and analyses. Each rectifier unit delivers near-sinusoidal current waveforms at unity (or even leading) power factor. Of particular concern are the questions of: (i) system stability; (ii) the capability of the modular units to share voltage (series connection) and current (parallel

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

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

    SciTech Connect

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

    2014-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  12. On planar rational cuspidal curves

    E-print Network

    Liu, Tiankai

    2014-01-01

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

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

    SciTech Connect

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

    2014-09-28

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

  14. Magnetic viscosity, hysteresis reptation, and their relationship with adjacent track interference in advanced perpendicular recording media

    NASA Astrophysics Data System (ADS)

    Srinivasan, Kumar; Roddick, Eric

    2012-08-01

    The role of exchange interactions and thermal relaxation in advanced three-layer exchange-coupled composite perpendicular recording media with graded anisotropy was investigated through studies on magnetic viscosity, magnetic hysteresis reptation, and spin-stand adjacent track interference. For this purpose, thickness series in the NiW seed and the three magnetic layers were made and studied. For each sample, both magnetic viscosity and reptation were evaluated using a magnetometer over a series of initial magnetic states. Magnetic viscosity, which is the change in the magnetization of the sample with time, showed a distinct second-order dependence on a logarithmic time-scale. In general, viscosity appeared to be more strongly influenced by exchange-coupling interactions in the media than the thermal stability. Magnetic reptation, which is the change in the magnetization when the external field was repeatedly cycled between a nonzero field and zero field, i.e., remanence, showed two types of distinct reptation phenomena—field reptation and remanence reptation—depending on whether the magnetic state was evaluated with the external field present or removed, respectively. Both field and remanence reptation showed a second-order logarithmic dependence on the number of cycles. A comparison of viscosity and field reptation revealed a correlation, indicating that the origin of field reptation in perpendicular recording media can be associated with viscosity. Such a correlation could not be established between viscosity and remanence reptation. Spin-stand signal amplitude change of written tracks, due to adjacent track interference, also followed a second-order logarithmic dependence on the number of adjacent writes. When compared appropriately, the signal amplitude change showed an excellent correlation with remanence reptation across all media samples. This suggests that adjacent track interference in magnetic recording can be associated with remanence reptation evaluated using a magnetometer, despite their vast difference in time-scales. Moreover, this correlation was observed irrespective of the thermal stability of the media, which corroborates the hypothesis that in composite media, exchange interaction effects have a more dominant role than thermal relaxation effects in influencing switchability vis-à-vis adjacent track interference. In consequence, remanence reptation can be a useful technique to study the interplay of exchange and thermal effects in magnetic media.

  15. Guide to Elliptic Curve Cryptography

    E-print Network

    Babinkostova, Liljana

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

  16. Introduction Computations on Elliptic Curves

    E-print Network

    § Security Aspects § Implementation in Software and Hardware Elliptic Curve Cryptography #12;§ Problem equivalent security are desirable § Solution: Elliptic Curve Cryptography uses a group of points (instead.) § In cryptography, we are interested in elliptic curves module a prime p: § Note that Zp = {0,1,..., p -1} is a set

  17. Multiple CubicBezier Curves.

    ERIC Educational Resources Information Center

    Khonsari, Michael M.; Horn, Douglas

    1990-01-01

    An algorithm is described for generating smooth curves of first-order continuity. The algorithm is composed of several cubic Bezier curves joined together at the user defined control points. Introduced is a tension control parameter which can be set thus providing additional flexibility in the design of free-form curves. (KR)

  18. Titration Curves: Fact and Fiction.

    ERIC Educational Resources Information Center

    Chamberlain, John

    1997-01-01

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

  19. Modeling the Keeling Curve

    NSDL National Science Digital Library

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

  20. Fitting Blazhko light curves

    NASA Astrophysics Data System (ADS)

    Szeidl, B.; Jurcsik, J.; Sódor, Á.; Hajdu, G.; Smitola, P.

    2012-08-01

    The correct amplitude and phase modulation formalism of the Blazhko modulation is given. The harmonic order dependent amplitude and phase modulation form is equivalent to the Fourier decomposition of multiplets. The amplitude and phase modulation formalism used in electronic transmission technique as introduced by Benk?, Szabó & Paparó for Blazhko stars oversimplifies the amplitude and phase modulation functions; thus, it does not describe the light variation in full detail. The results of the different formalisms are compared and documented by fitting the light curve of a real Blazhko star, CM UMa.

  1. Lenses on curved surfaces.

    PubMed

    Mitchell-Thomas, R C; Quevedo-Teruel, O; McManus, T M; Horsley, S A R; Hao, Y

    2014-06-15

    This Letter presents a theory that allows graded index lenses to be mapped onto arbitrary rotationally symmetric curved surfaces. Examples of the Luneburg and Maxwell fish-eye lens are given, for numerous surfaces, always resulting in isotropic permittivity requirements. The performance of these lenses is initially illustrated with full-wave simulations utilizing a waveguide structure. A transformation of the refractive index profiles is then performed to design surface-wave lenses, where the dielectric layer is not only isotropic but also homogenous, demonstrating the applicability and ease of fabrication. PMID:24978534

  2. 2013 Goat Shows Show Date Show Name Entries Due Eligibility Weigh In Show Time Contact Phone Extra Info

    E-print Network

    Grissino-Mayer, Henri D.

    2013 Goat Shows Show Date Show Name Entries Due Eligibility Weigh In Show Time Contact Phone Extra/13/2013 Cannon Co. Day of Show Youth Must 8 a.m. to 12 p.m. Carol 615-563-5260 Bring own Jr. Goat $1.00 a head Control 10 a.m. Melton Bedding Association Goat 7/20/2013 Overton Co. Day of Show Youth Before 5 p.m. 6

  3. Experimental investigation on the hysteresis phenomenon and the photostrictive effect of PLZT with coupled multi-physics fields

    NASA Astrophysics Data System (ADS)

    Huang, J. H.; Wang, X. J.; Cheng, W. X.; Wang, J.

    2015-04-01

    Lead lanthanum zirconate (PLZT) ceramic has been widely studied as an opto-electromechanical actuator activated by ultraviolet light for active vibration control of various structures. However, the slow response time of photodeformation and the hysteresis phenomenon between the photovoltage and photo-induced deformation greatly affect the performance of PLZT as an actuator. The primary purposes of this article are to provide a comprehensive analysis on the hysteresis phenomenon and seek the reason of the hysteresis phenomenon with the experimental method. To this end, this study proposed the hysteresis phenomenon by photostrictive static experiments and investigated the possible influence factors on the hysteresis phenomenon through a series of experiments. The experimental results indicate that the temperature elevation of PLZT ceramic subjected to light illumination plays a significant role in the hysteresis phenomenon. Therefore, reducing the temperature rise of PLZT ceramic exposed to ultraviolet light is an effective means to eliminate the hysteresis phenomenon and improve the respond speed of photo-induced deformation.

  4. Automated reasoning about cubic curves.

    SciTech Connect

    Padmanabhan, R.; McCune, W.; Mathematics and Computer Science; Univ. of Manitoba

    1995-01-01

    It is well known that the n-ary morphisms defined on projective algebraic curves satisfy some strong local-to-global equational rules of derivation not satisfied in general by universal algebras. For example, every rationally defined group law on a cubic curve must be commutative. Here we extract from the geometry of curves a first order property (gL) satisfied by all morphisms defined on these curves such that the equational consequences known for projective curves can be derived automatically from a set of six rules (stated within the first-order logic with equality). First, the rule (gL) is implemented in the theorem-proving program Otter. Then we use Otter to automatically prove some incidence theorems on projective curves without any further reference to the underlying geometry or topology of the curves.

  5. Hysteresis in the conductance of asymmetrically biased GaAs quantum point contacts with in-plane side gates

    NASA Astrophysics Data System (ADS)

    Bhandari, N.; Dutta, M.; Charles, J.; Cahay, M.; Newrock, R. S.

    2013-07-01

    We have observed hysteresis between the forward and reverse sweeps of a common mode bias applied to the two in-plane side gates of an asymmetrically biased GaAs quantum point contact (QPC). The size of the hysteresis loop increases with the amount of bias asymmetry ?Vg between the two side gates and depends on the polarity of ?Vg. Our results are in qualitative agreement with Non-Equilibrium Green's Function simulations including the effects of dangling bond scattering on the sidewalls of the QPC. It is argued that hysteresis may constitute another indirect proof of spontaneous spin polarization in the narrow portion of the QPC.

  6. Fast-response single-inductor dual-output hysteresis-current-controlled DC–DC buck converter

    Microsoft Academic Search

    Jiann-Jong Chen; Bo-Han Hwang; Jui-Hsuan Hsu; Yuh-Shyan Hwang; Cheng-Chieh Yu

    A fast-response single-inductor dual-output hysteresis-current-controlled DC–DC buck is proposed for enhancing the transient\\u000a characteristics of switching DC–DC converters and fabricated with TSMC 0.35 ?m DPQM CMOS processes. By adopting a hysteresis-current-controlled\\u000a DC–DC buck converter, it is demonstrated that the hysteresis-current-controlled technique have improved dynamic response of\\u000a load variations whether the load current is light or heavy. Fast-response structure achieves 5 ?s response

  7. Extinction Effects in Spiral Galaxy Rotation Curves

    Microsoft Academic Search

    Carlos Valotto; Riccardo Giovanelli

    2004-01-01

    Observations show that the slope of the inner part of the Halpha\\/[N II] rotation curve of disk galaxies is depressed by extinction: at fixed luminosity, the observed slope is in fact seen to depend on the disk inclination to the line of sight. Using a simple extinction model, we are able to reproduce well the observed trends. The model assumes

  8. Singular interactions supported by embedded curves

    E-print Network

    Burak Tevfik Kaynak; O. Teoman Turgut

    2012-06-10

    In this work, singular interactions supported by embedded curves on Riemannian manifolds are discussed from a more direct and physical perspective, via the heat kernel approach. We show that the renormalized problem is well defined, the ground state is finite and the corresponding wavefunction is positive. The renormalization group invariance of the model is also discussed.

  9. 7Carbon Dioxide Increases The Keeling Curve,

    E-print Network

    7Carbon Dioxide Increases The Keeling Curve, shown to the left, shows the variation in concentration of atmospheric carbon dioxide since 1958-1974. It is based on continuous measurements taken of rapidly increasing carbon dioxide levels in the atmosphere. Additional measurements by scientists working

  10. Curved nanostructured materials

    NASA Astrophysics Data System (ADS)

    Terrones, Humberto; Terrones, Mauricio

    2003-10-01

    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 nanostructures with positive and negative Gaussian curvature. In this context, we will also demonstrate that hexagonal boron nitride, tungsten disulfide (WS2), molybdenum disulfide (MoS2) and rhenium disulfide (ReS2) are also able to create nanocages, nanotubes and nano-arrangements exhibiting novel physico-chemical properties that could revolutionize materials science in the 21st century.

  11. Understanding curved detonation waves

    SciTech Connect

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

    1993-06-01

    The reaction zone of a detonation wave is very small compared to the dynamic length scale for a typical application. Consequently, it is impractical for numerical calculations to fully resolve the reaction zone. A non-zero reaction zone width is critical to describe curved detonation waves because it affects the wave speed. The curvature effect is the result of an the interaction between the rate of energy release and geometric source terms within the reaction zone. When the reaction zone width is determined by the computational cell size rather than the physical scale, the numerics introduces an artificial curvature effect which frequently dominates the physical effect and leads to mesh dependence of simulations. Modified Hugoniot jump conditions are derived which characterize the curvature effect. They express the conservation laws and are not sensitive to the detailed reaction dynamics but instead depend only on the reaction zone width, and averages of pressure and of mass, momentum and energy densities.

  12. Understanding curved detonation waves

    SciTech Connect

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

    1993-01-01

    The reaction zone of a detonation wave is very small compared to the dynamic length scale for a typical application. Consequently, it is impractical for numerical calculations to fully resolve the reaction zone. A non-zero reaction zone width is critical to describe curved detonation waves because it affects the wave speed. The curvature effect is the result of an the interaction between the rate of energy release and geometric source terms within the reaction zone. When the reaction zone width is determined by the computational cell size rather than the physical scale, the numerics introduces an artificial curvature effect which frequently dominates the physical effect and leads to mesh dependence of simulations. Modified Hugoniot jump conditions are derived which characterize the curvature effect. They express the conservation laws and are not sensitive to the detailed reaction dynamics but instead depend only on the reaction zone width, and averages of pressure and of mass, momentum and energy densities.

  13. Ironing Out Curves

    NSDL National Science Digital Library

    2012-08-03

    In this activity, students graph second and third order functions, discovering an inverse relationship between squares and square roots and between cubes and cube roots. Students graph these functions on both linear grid (evenly spaced numbers), and a log-log grid (evenly space exponents). Graph lines that curve on linear grids transform into straight lines on the log-log grids, with slopes equal to their exponential powers. This activity is activity E3 in the "Far Out Math" educator's guide. Lessons in the guide include activities in which students measure, compare quantities as orders of magnitude, become familiar with scientific notation, and develop an understanding of exponents and logarithms using examples from NASA's GLAST mission. These are skills needed to understand the very large and very small quantities characteristic of astronomical observations. Note: In 2008, GLAST was renamed Fermi, for the physicist Enrico Fermi.

  14. Vortices on curved surfaces

    NASA Astrophysics Data System (ADS)

    Turner, Ari M.; Vitelli, Vincenzo; Nelson, David R.

    2010-04-01

    Topological defects in thin films coating a deformed substrate interact with the underlying curvature. This coupling mechanism influences the shape of biological structures and provides a new strategy for the design of interfaces with prescribed functionality. In this article, a mathematical formalism based on the method of conformal mapping that is presented permits the calculation of the energetics of disclinations, dislocations, and vortices on rigid substrates of spatially varying Gaussian curvature. Special emphasis is placed on determining the geometric force exerted on vortices in curved superfluid films. This force, which attracts (repels) vortices towards regions of negative (positive) Gaussian curvature, is an illustration of how material shape can influence quantum mechanical degrees of freedom.

  15. Birational maps that send biquadratic curves to biquadratic curves

    NASA Astrophysics Data System (ADS)

    Roberts, John A. G.; Jogia, Danesh

    2015-02-01

    Recently, many papers have begun to consider so-called non-Quispel?Roberts?Thompson (QRT) birational maps of the plane. Compared to the QRT family of maps which preserve each biquadratic curve in a fibration of the plane, non-QRT maps send a biquadratic curve to another biquadratic curve belonging to the same fibration or to a biquadratic curve from a different fibration of the plane. In this communication, we give the general form of a birational map derived from a difference equation that sends a biquadratic curve to another. The necessary and sufficient condition for such a map to exist is that the discriminants of the two biquadratic curves are the same (and hence so are the j-invariants). The result allows existing examples in the literature to be better understood and allows some statements to be made concerning their generality.

  16. Declining rotation curves in interacting galaxies

    NASA Technical Reports Server (NTRS)

    Dettmar, Ralf-Juergen; Skiff, Brian A.

    1993-01-01

    A declining rotation curve was recently found for the galaxy NGC 3521 by HI synthesis telescope observations (Casertano and van Gorkom 1991). From a comparison of the shapes of rotation curves for a larger sample of galaxies Casertano and van Gorkom argue that this is due to initial properties during the phase of galaxy formation. In several studies of global properties of galaxies, NGC 3521 was always considered a 'normal' unbarred, non-interacting, isolated spiral. However, we present CCD surface photometry that shows at low surface brightness levels the typical signs of interaction or even merging.

  17. Managing Beef Cattle for Show

    E-print Network

    Herd, Dennis B.; Boleman, Chris; Boleman, Larry L.

    2001-11-16

    This publication gives advice on raising beef cattle to exhibit at shows. Topics include animal selection, feeding, general health management, disease prevention, calf handling, and preparing for the show....

  18. What Do Blood Tests Show?

    MedlinePLUS

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

  19. Asia: Showing the Changing Seasons

    NSDL National Science Digital Library

    Jesse Allen

    1998-09-09

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

  20. 90 3. RIEMANNIAN MANIFOLDS (d) Show that the curves , : R G given in these coordinates

    E-print Network

    Godinho, Leonor

    vector v TpM, there exists a unique geodesic cv : I M defined on a maximal open interval I R) = p and (0) = acv(0) = av, we see that is the unique geodesic with initial condition av TpM, that is in some open neighborhood U of the origin in TpM. The map expp : U TpM M thus obtained is called