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1

Hysteresis loop and scanning curves of argon adsorption in closed-end wedge pores.  

PubMed

The hysteresis loop and scanning curves for argon adsorbed in a wedge pore with one end closed are studied with grand canonical Monte Carlo simulation. We have found multiple hysteresis loops for pores with either the narrow end or the wider end closed. In pores with the narrow end closed, adsorption and desorption exhibits a two-stage sequence of rapid change, followed by a gradual change in adsorbate density. The pore can be divided into zones of commensurate packing and junctions of incommensurate packing. A striking feature is that the sequence of these two stages is opposite for the adsorption and desorption processes. This can be explained by cohesion in the adsorbate, in which a steep condensation process is associated with the zones and a steep evaporation process is associated with the junctions between them. For pores with the wider end closed, the processes of adsorption and desorption from various zones are correlated with each other. In pores with the narrow end closed, the scanning curves trace reversibly along the segment of the isotherm, where the isotherm shows gradual change, and when the scanning curve reaches a point between the gradual change segment and the sharp change segment, the scanning curve crosses from one boundary of the hysteresis loop to the corresponding point on the other boundary. This indicates that the condensation and evaporation states are not affected by scanning but that, in scanning across the hysteresis loop, the adsorbate passes through a sequence of metastable states as the distribution of density is rearranged, without any significant change in the overall density. In contrast, for pores with the wider end closed, both the descending curve from a partially filled pore and the ascending curve are identical to the desorption branch of the corresponding pore with its narrow end closed. PMID:25314672

Klomkliang, Nikom; Do, D D; Nicholson, D

2014-11-01

2

Hysteresis and uncertainty in soil water-retention curve parameters  

USGS Publications Warehouse

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.

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

2014-01-01

3

perature sensitive. Both electrode pairs show approximately the same thermal hysteresis.  

E-print Network

. A. In "Ion-Selective Electrodes in Analytical Chemistry"; Freiser, H., Ed.; Plenum: New York, 1978 n "Ion-Seiectlve Electrodes"; Durst, R. A,, Ed.; National Bureauof Standards: Washington, DC, NBS236 perature sensitive. Both electrode pairs show approximately the same thermal hysteresis. The E

Mandelis, Andreas

4

Influence of experimental methods on crossing in magnetic force-gap hysteresis curve of HTS maglev system  

NASA Astrophysics Data System (ADS)

The crossing in magnetic levitation force-gap hysteresis curve of melt high-temperature superconductor (HTS) vs. NdFeB permanent magnet (PM) was experimentally studied. One HTS bulk and PM was used in the experiments. Four experimental methods were employed combining of high/low speed of movement of PM with/without heat insulation materials (HIM) enclosed respectively. Experimental results show that crossing of the levitation force-gap curve is related to experimental methods. A crossing occurs in the magnetic force-gap curve while the PM moves approaching to and departing from the sample with high or low speed of movement without HIM enclosed. When the PM is enclosed with HIM during the measurement procedures, there is no crossing in the force-gap curve no matter high speed or low speed of movement of the PM. It was found experimentally that, with the increase of the moving speed of the PM, the maximum magnitude of levitation force of the HTS increases also. The results are interpreted based on Maxwell theories and flux flow-creep models of HTS.

Lu, Yiyun; Qin, Yujie; Dang, Qiaohong; Wang, Jiasu

2010-12-01

5

Simulation study shows hysteresis effect on oil recovery during a cyclic steam process  

SciTech Connect

The cyclic steam stimulation of heavy oil reservoirs is often difficult to simulate, primarily because individual fluid mobilities change drastically from the injection portion of a cycle to the production portion. To improve simulation capabilities, 2 major approaches have been proposed: one based on hysteresis of relative permeability and capillary pressure, and the other on vertical fractures. The results of simulation studies using 2 different commercial steamflood models indicate that the hysteresis approach is the most suitable choice when a mobile water zone is present in the reservoir and when there is no evidence that a vertical fracture exists. This work reviews the underlying basis for hysteresis and temperature effects on relative permeability and capillary pressure and discusses simulation results obtained with a set of 3-phase functions in a cyclic steam stimulation of heavy oil reservoirs (9 to 11 API crude bitumen). 21 references.

Bang, H.W.

1984-02-27

6

Simulation study shows hysteresis effect on oil recovery during a cyclic steam process  

Microsoft Academic Search

The cyclic steam stimulation of heavy oil reservoirs is often difficult to simulate, primarily because individual fluid mobilities change drastically from the injection portion of a cycle to the production portion. To improve simulation capabilities, 2 major approaches have been proposed: one based on hysteresis of relative permeability and capillary pressure, and the other on vertical fractures. The results of

Bang

1984-01-01

7

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

8

Interior detail, building 810, view to north showing curved chord ...  

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

Interior detail, building 810, view to north showing curved chord sections of roof trusses, 90mm lens plus electronic flash fill lighting. - Travis Air Force Base, B-36 Hangar, Between Woodskill Avenue & Ellis, adjacent to Taxiway V & W, Fairfield, Solano County, CA

9

Vortex instability and hysteresis effects in I- V curves of superconducting Y 1Ba 2Cu 3O 7- ?  

NASA Astrophysics Data System (ADS)

We have investigated the effect of the current sweep rate (CSR) on the vortex dynamics in superconducting bulk sample of Y 1Ba 2Cu 3O 7- ?. It has been found that the CSR has several dramatic effects on the vortex motion by giving rise enhancement in dissipation as decreasing the CSR, significant time effects, and instabilities in current-voltage ( I- V) curves. The hysteresis loops concerning the I- V curves in both the current-increase and -decrease branches of the forward current region, and also the branches of the reversed current region have been observed together with a gradual diminutive of the hysteresis effects with decreasing the CSR. Due to the field and temperature domain considered, it is also observed that the moving state becomes unstable giving rise some instabilities such as small jumps and steps for both low and moderate current values as a function of CSR. Those anomalies have been discussed in terms of the depinning-pinning correlated to the plastic flow regime together with the disorder in the coupling strength between the superconducting grains, and compared qualitatively to the numerical computer simulations. In addition, for a given field and temperature domain, it has been shown that the CSR together with a relevant current scale is of importance in evolution of the I- V curves and is a useful tool in investigating the details of the vortex dynamics.

Kiliç, A.; Kiliç, K.; Çetin, O.

2003-02-01

10

Thermohaline circulation hysteresis: A model intercomparison  

Microsoft Academic Search

We present results from an intercomparison of 11 different climate models of intermediate complexity, in which the North Atlantic Ocean was subjected to slowly varying changes in freshwater input. All models show a characteristic hysteresis response of the thermohaline circulation to the freshwater forcing; which can be explained by Stommel's salt advection feedback. The width of the hysteresis curves varies

Stefan Rahmstorf; Michel Crucifix; Andrey Ganopolski; Hugues Goosse; Igor Kamenkovich; Reto Knutti; Gerrit Lohmann; Robert Marsh; Lawrence A. Mysak; Zhaomin Wang; Andrew J. Weaver

2005-01-01

11

Hysteresis Simulation  

NSDL National Science Digital Library

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

Houle, Paul

12

Hysteresis characterization using charge feedback control for a LIPCA device  

NASA Astrophysics Data System (ADS)

In this paper, we study the no-load behavior of a lightweight piezo-composite curved actuator (LIPCA) subjected to voltage and charge control. First, we examine the effect of hysteresis and creep when the actuator is voltage controlled at a slow scan speed. The experimental results show that creep increases the displacement hysteresis by over 25% when scanning at 1/60 Hz. Afterwards, we discuss the design and implementation of a charge-feedback circuit to control the displacement of the actuator. The hysteresis curves between voltage- and charge-control modes are compared for the scan frequencies of 1 and 5 Hz. The results show that charge control (compared to voltage control) of a LIPCA device exhibits significantly less hysteresis, over 80% less.

Beck, James; Noras, Maciej; Kieres, Jerzy; Speich, John E.; Mossi, Karla M.; Leang, Kam K.

2006-03-01

13

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

14

Plant thermal hysteresis proteins.  

PubMed

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

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

1992-05-22

15

A magnetic hysteresis model  

NASA Technical Reports Server (NTRS)

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.

Flatley, Thomas W.; Henretty, Debra A.

1995-01-01

16

Mathematical models of hysteresis  

SciTech Connect

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

NONE

1998-08-01

17

ASYNCHRONOUS PERFORMANCES OF HYSTERESIS MOTORS UNDER UNBALANCED CONDITIONS  

Microsoft Academic Search

The torque-speed curves of an hysteresis motor under unbalanced conditions are computed by a numerical method. The magnetic characteristic of the rotor ring is represented by the Preisach-Néel's model. This method takes into account the minor loops which appear on the B(H) characteristic in the case under consideration. Computed and experimental curves are compared. This work shows that eddy currents

J. PERARD; M. POLOUJADOFF

1977-01-01

18

[Mathematical models of hysteresis  

SciTech Connect

The research described in this proposal is currently being supported by the US Department of Energy under the contract Mathematical Models of Hysteresis''. Thus, before discussing the proposed research in detail, it is worthwhile to describe and summarize the main results achieved in the course of our work under the above contract. Our ongoing research has largely been focused on the development of mathematical models of hysteretic nonlinearities with nonlocal memories''. The distinct feature of these nonlinearities is that their current states depend on past histories of input variations. It turns out that memories of hysteretic nonlinearities are quite selective. Indeed, experiments show that only some past input extrema leave their marks upon future states of hysteretic nonlinearities. Thus special mathematical tools are needed in order to describe nonlocal selective memories of hysteretic nonlinearities. Our research has been primarily concerned with Preisach-type models of hysteresis. All these models have a common generic feature; they are constructed as superpositions of simplest hysteretic nonlinearities-rectangular loops. Our study has by and large been centered around the following topics: various generalizations and extensions of the classical Preisach model, finding of necessary and sufficient conditions for the representation of actual hysteretic nonlinearities by various Preisach type models, solution of identification problems for these models, numerical implementation and experimental testing of Preisach type models. Although the study of Preisach type models has constituted the main direction of the research, some effort has also been made to establish some interesting connections between these models and such topics as: the critical state model for superconducting hysteresis, the classical Stoner-Wohlfarth model of vector magnetic hysteresis, thermal activation type models for viscosity, magnetostrictive hysteresis and neural networks.

Mayergoyz, I.D.

1991-01-01

19

EXPERIMENTAL MEASUREMENTS OF CAPILLARY PRESSURE AND RELATIVE PERMEABILITY HYSTERESIS  

Microsoft Academic Search

Capillary pressure and relative permeability hysteresis have been investigated on core samples with different wetting characteristics. The relative permeability and capillary pressure curves depend on the direction of saturation changes and on the maximum and minimum achieved saturations. A conceptual model to explain the hysteresis trends in both the relative permeability and capillary pressure is presented. The model attributes hysteresis

Shehadeh K. Masalmeh

20

The magnetization process: Hysteresis  

NASA Technical Reports Server (NTRS)

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

Balsamel, Richard

1990-01-01

21

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 with the Keeling Curve data that indicates a net annual increase of carbon dioxide of +11 gigatons/year? Space Math answer for the net change in Problem 2 match up with the Keeling Curve data that indicates a net annual

22

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

SciTech Connect

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

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

2004-03-12

23

Anomalous Ferroelectric Hysteresis Loops.  

National Technical Information Service (NTIS)

Materials that exhibit anomalous ferroelectric hysteresis loops appear throughout the literature. These loops have irregular shapes that diverge from the normal hysteresis loop which is characteristic of most ferroelectrics. The observation of a unique hy...

F. J. Murdoch

1971-01-01

24

Magnetization Process: Hysteresis.  

National Technical Information Service (NTIS)

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

R. Balsamel

1990-01-01

25

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

26

Design of experiment for hysteresis loops measurement  

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

27

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

PubMed Central

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

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

2014-01-01

28

Analysis of wasp-waist hysteresis loops  

NASA Astrophysics Data System (ADS)

Wasp-waist and pot-belly hysteresis loops have been observed in many materials. When only the major loop is reported, the results are insufficient to establish which processes are involved. We present two models for wasp-waist materials that produce virtually indistinguishable major loops, but show that first-order reversal curves can be used to separate the effects. In the simplest model, we take a soft magnetic material and a hard material and exchange couple them. When the exchange is positive, the loop is conventional. However, for negative (antiferromagnetic) exchange, the wasp-waist loop is obtained. Negative coupling of two materials with different switching field distributions leads to pot-bellied loops.

Bennett, Lawrence H.; Della Torre, Edward

2005-05-01

29

Mathematical models of hysteresis  

Microsoft Academic Search

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.

I. Mayergoyz

1986-01-01

30

Hysteresis in Metal Hydrides.  

ERIC Educational Resources Information Center

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

Flanagan, Ted B., And Others

1987-01-01

31

Efficient Computational Model of Hysteresis  

NASA Technical Reports Server (NTRS)

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.

Shields, Joel

2005-01-01

32

Magnetoimpedance hysteresis in amorphous microwires induced by core-shell interaction  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

33

Hysteresis in a quantized superfluid `atomtronic' circuit  

NASA Astrophysics Data System (ADS)

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).

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

34

Hysteresis in a quantized superfluid 'atomtronic' circuit.  

PubMed

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). PMID:24522597

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

2014-02-13

35

Torque calculation of hysteresis motor using vector hysteresis model  

Microsoft Academic Search

This paper presents how to determine the thickness of the hysteresis ring of hysteresis motor using the finite element method combined with a vector hysteresis model. From the magnitude and direction of the magnetic field intensity, the magnetization of each ring element is calculated by the vector hysteresis model and the torque can be obtained from the vector sum of

Sun-Ki Hong; Kong-Kyu Kim; Hyeong-Seok Kim; Hyun-Kyo Jung

2000-01-01

36

Hysteresis effects in Bose-Einstein condensates  

E-print Network

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

Andrea Sacchetti

2010-06-16

37

STP Hysteresis Program  

NSDL National Science Digital Library

The STP Hysteresis program is a Monte Carlo simulation of a two-dimensional Ising model demonstrating that the magnetization does not immediately change when the external magnetic field is changed. The default is a lattice of linear dimension L=32 (for a total of N=L^2 spins), a temperature T=1.8 and an external field that changes from H=1 to H=-1 and then returns to its original value. STP Hysteresis is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double clicking the stp_Hysteresis.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2009-03-13

38

Dynamical aspects of the adsorption hysteresis phenomenon.  

PubMed

Equilibrium and nonequilibrium transport properties of adsorbates in mesoporous Vycor porous glass have been experimentally studied using nuclear magnetic resonance techniques. With the known geometrical characteristics of porous glass and with measured self-diffusivities, transient sorption curves have been quantitatively compared to those predicted within a Fick's law model. This model correctly describes data outside a hysteresis region. In contrast, in the hysteresis region, a two-step mechanism of density relaxation is required to explain the behavior. These two mechanisms are identified as diffusion at early stages and activated density redistribution at later stages of adsorption. The latter mechanism, being intrinsically slow in nature, is anticipated to prevent the system from reaching equilibrium. PMID:17466768

Valiullin, Rustem; Naumov, Sergej; Galvosas, Petrik; Kärger, Jörg; Monson, Peter A

2007-05-01

39

Positive hysteresis of Ce-doped GAGG scintillator  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

40

Thermal hysteresis proteins.  

PubMed

Extreme environments present a wealth of biochemical adaptations. Thermal hysteresis proteins (THPs) have been found in vertebrates, invertebrates, plants, bacteria and fungi and are able to depress the freezing point of water (in the presence of ice crystals) in a non-colligative manner by binding to the surface of nascent ice crystals. The THPs comprise a disparate group of proteins with a variety of tertiary structures and often no common sequence similarities or structural motifs. Different THPs bind to different faces of the ice crystal, and no single mechanism has been proposed to account for THP ice binding affinity and specificity. Experimentally THPs have been used in the cryopreservation of tissues and cells and to induce cold tolerance in freeze susceptible organisms. THPs represent a remarkable example of parallel and convergent evolution with different proteins being adapted for an anti-freeze role. PMID:11240367

Barrett, J

2001-02-01

41

A modified Jiles method for hysteresis computation including minor loops  

NASA Astrophysics Data System (ADS)

This work presents a new methodology for determination of hysteresis curves based on the Jiles-Atherton method. The magnetic induction is adopted as an independent variable which is available in the vector potential magnetic field formulation. The presented method can be directly incorporated in a finite element software.

Koltermann, P. I.; Righi, L. A.; Bastos, J. P. A.; Carlson, R.; Sadowski, N.; Batistela, N. J.

2000-01-01

42

Optimizing the Jiles-Atherton model of hysteresis by a genetic algorithm  

Microsoft Academic Search

Modeling magnetic components for simulation in electric circuits requires an accurate model of the hysteresis loop of the core material used. It is important that the parameters extracted for the hysteresis model be optimized across the range of operating conditions that may occur in circuit simulation. This paper shows how to extract optimal parameters for the Jiles-Atherton model of hysteresis

Peter R. Wilson; J. Neil Ross; Andrew D. Brown

2001-01-01

43

Analysis of hysteresis motor using finite element method and magnetization-dependent model  

Microsoft Academic Search

In this paper, finite element analysis (FEA) of a hysteresis motor using a magnetization-dependent model is presented. The hysteresis loop in the hysteresis ring is calculated from the maximum flux density which is obtained by the FEA. The proposed method is applied to a sample motor and the simulation result shows a very good agreement with the experimental one. Various

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

2000-01-01

44

The significance of observed rotational magnetic hysteresis in lunar samples  

NASA Technical Reports Server (NTRS)

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

Wasilewski, P.

1974-01-01

45

Mathematical Models of Hysteresis (Dynamic Problems in Hysteresis).  

National Technical Information Service (NTIS)

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 magne...

I. Mayergoyz

2006-01-01

46

Hysteresis and magnetostriction of TbxDyyHo1-x-yFe1.95 [112] dendritic rods  

NASA Astrophysics Data System (ADS)

The magnetization and magnetostriction of a variety of 3/16-in.-diam Laves phase rods of TbxDyyHo1-x-yFe1.95 grown in the form of [112] oriented dendritic compounds were measured as a function of applied magnetic field -3000hysteresis with only slightly lower magnetostriction. The Ho concentration was kept relatively small (?0.3) to avoid a substantial decrease in the magnetostriction, while the ratio of x and y was chosen to examine alloys spanning the line of minimum magnetic anisotropy. Most of the compositions have twice the Ho content of the previous study. As expected, alloys with higher Ho concentrations showed narrower hysteresis curves. The data shows that at 22 MPa, the Tb0.28Dy0.57Ho0.15Fe1.95 composition has a minimal (3%) loss of magnetostriction, while the hysteresis width decreased by 15%. Between 15% and 20% Ho content, the magnetostriction drops abruptly. For alloys with a fixed Ho concentration, the strain showed a peak near the expected anisotropy minimum, but the hysteresis width always increased with increasing Tb content.

Wun-Fogle, M.; Restorff, J. B.; Clark, A. E.

1999-04-01

47

Hysteresis Model for Piezoceramic Materials.  

National Technical Information Service (NTIS)

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 ...

R. C. Smith, Z. Ounaies

1999-01-01

48

Numerical modelling in the time domain of dynamic hysteresis of soft materials in cylindrical coordinates  

NASA Astrophysics Data System (ADS)

This paper deals with the numerical analysis of soft magnetic materials with hysteresis in dynamic axial symmetric problems. We present a procedure based on a 1D Finite Difference Time Domain (FDTD) algorithm where there are implemented magnetization dependent Preisach based models. Experimental measurements of the virgin curve and the major loop are used to identify the models. The numerical scheme in the time domain proposed is discussed and a probe of its intrinsic stability is given. Numerical codes based on the above algorithm are used to show some of the possibilities of this numerical tool for the dynamic magnetic analysis.

Cardelli, Ermanno; Torre, Edward Della; Pinzaglia, Enrico

2003-05-01

49

High contact angle hysteresis of superhydrophobic surfaces: Hydrophobic defects  

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

50

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

PubMed

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

Duman, J G

1994-05-18

51

Revisiting the hysteresis effect in surface energy budgets  

NASA Astrophysics Data System (ADS)

The hysteresis effect in diurnal cycles of net radiation Rn and ground heat flux G0 has been observed in many studies, while the governing mechanism remains vague. In this study, we link the phenomenology of hysteresis loops to the wave phase difference between the diurnal evolutions of various terms in the surface energy balance. Rn and G0 are parameterized with the incoming solar radiation and the surface temperature as two control parameters of the surface energy partitioning. The theoretical analysis shows that the vertical water flux W and the scaled ratio As*>/AT* (net shortwave radiation to outgoing longwave radiation) play crucial roles in shaping hysteresis loops of Rn and G0. Comparisons to field measurements indicate that hysteresis loops for different land covers can be well captured by the theoretical model, which is also consistent with Camuffo-Bernadi formula. This study provides insight into the surface partitioning and temporal evolution of the energy budget at the land surface.

Sun, Ting; Wang, Zhi-Hua; Ni, Guang-Heng

2013-05-01

52

Dynamic Hysteresis in Compacted Magnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

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).

Chowdary, Krishna M.

53

Hysteresis in quantized vortex shedding  

NASA Astrophysics Data System (ADS)

It is shown using numerical simulations that flow patterns around an obstacle potential moving in a superfluid exhibit hysteresis. In a certain velocity region, there is a bistability between stationary laminar flow and periodic vortex shedding. The bistability exists in two- and three-dimensional systems.

Kadokura, Tsuyoshi; Yoshida, Jun; Saito, Hiroki

2014-07-01

54

Comparative experiments regarding approaches to feedforward hysteresis compensation for piezoceramic actuators  

NASA Astrophysics Data System (ADS)

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.

Gu, Guo-Ying; Zhu, Li-Min

2014-09-01

55

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

SciTech Connect

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

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

1999-05-01

56

Completely inverted hysteresis loops: Inhomogeneity effects or experimental artifacts  

SciTech Connect

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.

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

57

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

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.

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

58

Performance predictions for large hysteresis motors  

Microsoft Academic Search

This paper examines the possibilities of designing large, integral-horsepower hysteresis motors to have efficiency and power factor comparable with that of induction motors. Scaling techniques are used, together with a previously published analytical method, to scale up an existing laboratory hysteresis motor of 3 kW rating. The resulting design for a 200 kW hysteresis motor is predicted to have an

G. R. Slemon; R. D. Jackson; M. A. Rahman

1977-01-01

59

Hysteresis phenomenon in turbulent convection  

E-print Network

Coherent large-scale circulations of turbulent thermal convection in air have been studied experimentally in a rectangular box heated from below and cooled from above using Particle Image Velocimetry. The hysteresis phenomenon in turbulent convection was found by varying the temperature difference between the bottom and the top walls of the chamber (the Rayleigh number was changed within the range of $10^7 - 10^8$). The hysteresis loop comprises the one-cell and two-cells flow patterns while the aspect ratio is kept constant ($A=2 - 2.23$). We found that the change of the sign of the degree of the anisotropy of turbulence was accompanied by the change of the flow pattern. The developed theory of coherent structures in turbulent convection (Elperin et al. 2002; 2005) is in agreement with the experimental observations. The observed coherent structures are superimposed on a small-scale turbulent convection. The redistribution of the turbulent heat flux plays a crucial role in the formation of coherent large-scal...

Eidelman, A; Kleeorin, N; Markovich, A; Rogachevskii, I

2006-01-01

60

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

NASA Astrophysics Data System (ADS)

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.

Kocakaplan, Yusuf; Keskin, Mustafa

2014-09-01

61

Semiempirical model of soil water hysteresis  

USGS Publications Warehouse

In order to represent hysteretic soil water retention curves accurately using as few measurements as possible, a new semiempirical model has been developed. It has two postulates related to physical characteristics of the medium, and two parameters, each with a definite physical interpretation, whose values are determined empirically for a given porous medium. Tests of the model show that it provides high-quality optimized fits to measured water content vs. matric pressure wetting curves for a wide variety of media. A practical use of this model is to provide a complete simulated main wetting curve for a medium where only a main drying curve and two points on the wetting curve have been measured. -from Author

Nimmo, J. R.

1992-01-01

62

Study on the hunting in high speed hysteresis motors due to the rotor hysteresis material  

Microsoft Academic Search

Hysteresis motors behave very much like to classical synchronous motors, except that the motor magnetic pole definition varies slightly with torque. This paper presents a study on the hunting of a radial-flux type, high speed hysteresis motor caused by the hysteresis material of the rotor. Firstly, a nonlinear dynamic model of the PWM-controlled hysteresis motor drive is developed in d-q

H. R. Soroush; A. R. Rahmati; H. Moghbelli; A. Vahedi; A. H. Niasar

2009-01-01

63

MATHEMATICAL MODELS OF HYSTERESIS (DYNAMIC PROBLEMS IN HYSTERESIS)  

SciTech Connect

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.

Professor Isaak Mayergoyz

2006-08-21

64

Subsynchronous torque calculation in a shaded pole hysteresis motor  

Microsoft Academic Search

This paper deals with the synchronous dips in the torque-speed characteristic of a shaded pole hysteresis motor. The case under consideration is that of the synchronous dip related to the third harmonic of the air-gap field. First we show that the torque Varies between a maximum and a minimum value when the motor runs at one third of synchronous speed

J. Perard; M. Poloujadoff

1976-01-01

65

Hidden hysteresis - population dynamics can obscure gene network dynamics  

PubMed Central

Background Positive feedback is a common motif in gene regulatory networks. It can be used in synthetic networks as an amplifier to increase the level of gene expression, as well as a nonlinear module to create bistable gene networks that display hysteresis in response to a given stimulus. Using a synthetic positive feedback-based tetracycline sensor in E. coli, we show that the population dynamics of a cell culture has a profound effect on the observed hysteretic response of a population of cells with this synthetic gene circuit. Results The amount of observable hysteresis in a cell culture harboring the gene circuit depended on the initial concentration of cells within the culture. The magnitude of the hysteresis observed was inversely related to the dilution procedure used to inoculate the subcultures; the higher the dilution of the cell culture, lower was the observed hysteresis of that culture at steady state. Although the behavior of the gene circuit in individual cells did not change significantly in the different subcultures, the proportion of cells exhibiting high levels of steady-state gene expression did change. Although the interrelated kinetics of gene expression and cell growth are unpredictable at first sight, we were able to resolve the surprising dilution-dependent hysteresis as a result of two interrelated phenomena - the stochastic switching between the ON and OFF phenotypes that led to the cumulative failure of the gene circuit over time, and the nonlinear, logistic growth of the cell in the batch culture. Conclusions These findings reinforce the fact that population dynamics cannot be ignored in analyzing the dynamics of gene networks. Indeed population dynamics may play a significant role in the manifestation of bistability and hysteresis, and is an important consideration when designing synthetic gene circuits intended for long-term application. PMID:23800122

2013-01-01

66

Steady-State Performance of Polyphase Hysteresis-Reluctance Motors  

Microsoft Academic Search

It is well known that the hysteresis-reluctance motor produces a torque that combines hysteresis and reluctance effects. Consequently, the performance characteristics would be increased when compared to that of the plain hysteresis motor. This paper presents a new design of a hysteresis-reluctance rotor in which the magnetic saliency was created by cutting slots in the inside diameter of the hysteresis

M. A. Rahman; A. M. Osheiba

1986-01-01

67

Bradford Curves.  

ERIC Educational Resources Information Center

Discussion of informetric distributions shows that generalized Leimkuhler functions give proper fits to a large variety of Bradford curves, including those exhibiting a Groos droop or a rising tail. The Kolmogorov-Smirnov test is used to test goodness of fit, and least-square fits are compared with Egghe's method. (Contains 53 references.) (LRW)

Rousseau, Ronald

1994-01-01

68

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

E-print Network

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.

Falko Ziebert; Hervé Mohrbach; Igor M. Kuli?

2014-05-18

69

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

E-print Network

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.

Ziebert, Falko; Kuli?, Igor M

2014-01-01

70

Characteristic analysis of hysteresis-type Bi-2223 bulk motor with the use of equivalent circuit  

NASA Astrophysics Data System (ADS)

Characteristics of a hysteresis-type Bi-2223 bulk motor were studied based on the equivalent circuit. The Bi-2223 bulk motor consists of a disk shaped Bi-2223 bulk rotor and a 3-phase, 4-pole stator. The locked-rotor test results were discussed in this study. Stator impedance was directly obtained through the measurement, and then the rotor resistance was estimated from the equivalent circuit with some assumptions. In order to show the validity of the equivalent circuit, the experimental results were compared with the calculated results using the circuit. It was shown that the calculated results of the torque curves agree semi-quantitatively with the experimental results. Based on the equivalent circuit, temperature dependence of the rotor resistance is also to be presented and discussed.

Jung, H. J.; Nakamura, T.; Tanaka, N.; Muta, I.; Hoshino, T.

2004-06-01

71

Dynamic performance prediction of polyphase hysteresis motors  

Microsoft Academic Search

The dynamic performance characteristics of polyphase hysteresis motors are presented. A mathematical model to predict the starting and synchronization process of such motors under various operating conditions is given. The model offers a tool for studying the dynamic stability of the hysteresis motor for small-scale disturbances such as changes in load torque, supply voltage, and frequency. A parametric variation is

M. A. Rahman; ALI M. OSHEIBA

1990-01-01

72

Equivalent Circuit Modeling of Hysteresis Motors  

Microsoft Academic Search

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

J J Nitao; E T Scharlemann; B A Kirkendall

2009-01-01

73

Field Analysis of Polyphase Hysteresis Motor  

Microsoft Academic Search

A comprehensive theoretical field model has been developed for hysteresis motors. Using the stator current sheet technique, the motor field equations are rigoriously derived for the air gap and hysteresis ring regions. The analysis takes into account the contribution of the reaction field of rotor magnetization to the primary air gap field due to stator current sheets alone. Unlike induction

M. A. Rahman

1980-01-01

74

Analysis of a hysteresis motor with overexcitation  

Microsoft Academic Search

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

T. Kataoka; T. Ishikawa; T. Takahashi

1982-01-01

75

Study of a Radial-Exiting Hysteresis Gyro Motor.  

National Technical Information Service (NTIS)

Conventional hysteresis motors have small ratios of the output power to the motor volume as compared with conventional induction motors, because the hysteresis materials have small hysteresis loops. A new rotor structure is proposed in which anisotropic m...

H. Yamada

1973-01-01

76

Contact Angle Hysteresis on Superhydrophobic Stripes  

E-print Network

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 $\\phi_S\\leq 0.2$.

Alexander L. Dubov; Ahmed Mourran; Martin Möller; Olga I. Vinogradova

2014-02-11

77

Hysteresis and after-effects in massive substances. From spin-glasses to the sand hill  

E-print Network

to the spin-glass case. The magnetization relaxations at different temperatures (S(T) curves) and the Fulcher1095 Hysteresis and after-effects in massive substances. From spin-glasses to the sand hill J]. This will be done with the particular hindsight resulting from our spin-glass directed state of mind N6el

Boyer, Edmond

78

Modelling the Hysteresis of Interacting Pseudo-Single-Domain Magnetite Particles  

NASA Astrophysics Data System (ADS)

Recent studies have shown the importance of fine magnetite exsolution structures as remanence carriers in igneous rocks. These structures often form arrays of tightly spaced individual grains straddling the single domain (SD) to pseudo-single-domain (PSD) threshold. Due to the proximity of neighbouring particles, magnetostatic interactions are expected to play an important role for the magnetic properties of these particle assemblages. We have used an unconstrained, fully three dimensional finite element (FE) micromagnetic model to calculate hysteresis curves of 3x3 arrays of magnetite particles with aligned easy axes with grain sizes r=50 ... 200nm and grain spacings d=0 ... 3· r . The calculations show that the domain state of individual particles is not only dependent on their grain size but also on the grain separation. Closer d generally leads to an increased SD-PSD size threshold. Associated with that is a characteristic change in magnetic stability: For d<50nm MRS/MS decreases sharply for all modelled grain sizes. This decrease is related to the appearance of supervortex structures at zero external field. Our modelling approach allowed us to observe the formation of these supervortices in the course of a hysteresis cycle. As expected, SD sized particles retain a uniform particle magnetisation throughout the whole hysteresis cycle. The particle arrays, however, form intermediate supervortex structures even for relatively large d because the individual particles' magnetisation cannot collapse into a vortex state to reduce its magnetic stray field. Only when the spacing increases to 150nm (i. e. d=3· r), does the magnetisation of all particles in the array rotate coherently. In contrast, PSD particle arrays generally reverse their magnetisation by spin curling and the formation of individual vortex states. For almost touching particles, though, an SD like magnetisation structure of individual grains is maintained throughout the hysteresis cycle by forming supervortex states. The individual vortex state, however, is energetically more favourable as soon as d is only slightly increased. The paper will discuss the particle size and spacing dependence of the average interaction field and its influence on magnetic grain size determinations.

Krása, D.; Williams, W.

2007-12-01

79

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

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

80

The capillary hysteresis model HYSTR: User`s guide  

SciTech Connect

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

Niemi, A.; Bodvarsson, G.S.

1991-11-01

81

Hysteresis critical point of nitrogen in porous glass: occurrence of sample spanning transition in capillary condensation.  

PubMed

To examine the mechanisms for capillary condensation and for capillary evaporation in porous glass, we measured the hysteresis critical points and desorption scanning curves of nitrogen in four kinds of porous glasses with different pore sizes (Vycor, CPG75A, CPG120A, and CPG170A). The shapes of the hysteresis loop in the adsorption isotherm of nitrogen for the Vycor and the CPG75A changed with temperature, whereas those for the CPG120A and the CPG170A remained almost unchanged with temperature. The hysteresis critical points for the Vycor and the CPG75A fell on the common line observed previously for ordered mesoporous silicas. On the other hand, the hysteresis critical points for the CPG120A and the CPG170A deviated appreciably from the common line. This strongly suggests that capillary evaporation of nitrogen in the interconnected and disordered pores of both the Vycor and the CPG75A follows a cavitation process at least in the vicinity of their hysteresis critical temperatures in the same way as that in the cagelike pores of the ordered silicas, whereas the hysteresis critical points in the CPG120A and the CPG170A have origin different from that in the cagelike pores. The desorption scanning curves for the CPG75A indicated the nonindependence of the porous domains. On the other hand, for both the CPG120A and the CPG170A, we obtained the scanning curves that are expected from the independent domain theory. All these results suggest that sample spanning transitions in capillary condensation and evaporation take place inside the interconnected pores of both the CPG120A and the CPG170A. PMID:19466781

Morishige, Kunimitsu

2009-06-01

82

Trapping and hysteresis in two-phase flow in porous media 1: Pore-network modeling  

NASA Astrophysics Data System (ADS)

The parameters and parameter functions of classical formulations of two-phase flow in porous media - the relative permeability - saturation relationship, the capillary pressure - saturation relationship, and the associated residual saturations - show path dependence, i.e. their values depend not only on the state variables but also on their drainage and imbibition history. Many models incorporate these hysteretic effects through ad-hoc adaptations based on fitting curves to experimental data. In addition, various physically based models identify different pore-scale phenomena as crucial. They range from Preisach-type models for dependent or independent domains, to identifying new state variables - e.g. interfacial area or non-percolating fluid saturations - to resolve hysteresis. Several models identify trapping and connectivity of fluids as an important contribution to macro-scale hysteresis. This is especially true for hysteresis in relative permeabilities. The trapping models propose trajectories from the initial saturation to the end saturation in various ways and are based on experiments or pore-network model results for the endpoints. However, experimental data or pore-scale model results are not available for the trajectories, i.e. the fate of the connectivity of the fluids while saturation changes. Hence, a validation of the different models is yet to be accomplished. Here, using a quasi-static pore-network model we study how the topology of the fluids changes during drainage and imbibition for different initial saturations. The pore-network has been developed for different polygonal geometries to permit different degrees of corner flow and residual saturations in the crevices. The effect of pore geometry and flow history on continuum-scale variables such as capillary pressure, phase relative permeabilities, and non-connected non-wetting phase saturation, have been studied as a function of total wetting phase saturation. We find a strong hysteretic behavior in the relationship between non-connected non-wetting fluid saturation and the wetting fluid saturation as well as relative permeability curves. This hysteretic behavior is pronounced in angular cross section domains, where the corner flow is important.

Joekar-Niasar, V.; Doster, F.; Nordbotten, J. M.; Celia, M. A.

2011-12-01

83

Percolation model of relative permeability hysteresis  

NASA Astrophysics Data System (ADS)

A mathematical model of relative permeability hysteresis in drainage and imbibition is constructed on the basis of percolation theory. It is shown that the results are in qualitatively agreement with experimental data.

Kadet, V. V.; Galechyan, A. M.

2013-05-01

84

Quantized hysteresis in a superfluid atomtronic circuit  

E-print Network

Atomtronics is an emerging interdisciplinary field that seeks new functionality by creating devices and circuits where ultra-cold atoms play a role analogous to the electrons in electronics. Hysteresis in atomtronic circuits may prove to be a crucial feature for the development of practical devices, just as it has in electronic circuits like memory, digital noise filters (e.g., Schmitt triggers), and magnetometers (e.g., superconducting quantum interference devices [SQUIDs]). Here we demonstrate quantized hysteresis in an atomtronic circuit: a ring of superfluid, dilute-gas, Bose-Einstein condenstate (BEC) obstructed by a rotating weak link. Hysteresis is as fundamental to superfluidity (and superconductivity) as quantized persistent currents, critical velocity, and Josephson effects, but has not been previously observed in any atomic-gas, superfluid BEC despite multiple theoretical predictions. By contrast, hysteresis is routinely observed in superconducting circuits, and it is essential in rf-SQUIDs. Superf...

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

2014-01-01

85

Analysis of hunting in Synchronous Hysteresis Motor  

E-print Network

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 ...

Truong, Cang Kim, 1979-

2004-01-01

86

PERFORMANCE OF HYSTERESIS PERMANENT MAGNET MOTORS  

Microsoft Academic Search

There is an increasing interest in using permanent magnet (PM) hysteresis motors because of their superior performances over the conventional hysteresis motors. Recent NdBFe magnets have the advantages of higher magnetic energy product and remanence. It can develop significant accelerating torque during run-up and synchronization with limited temperature tolerance. The application of the NdBFe magnets in electrical machines Is attracting

A. M. OSHEIBA; J. QIAN; M. A. RAHMAN

1989-01-01

87

Dynamic performance prediction of hysteresis motors  

Microsoft Academic Search

The dynamic performance characteristics of polyphase hysteresis motors are presented. A mathematical model, based on the d-q-axis theory, for predicting the starting and synchronization processes of such motors under various operating conditions is presented. The model offers a tool for studying the dynamic stability of the hysteresis motor for small-scale disturbances such as load torque, supply voltage, and frequency. Moreover,

M. A. Rahman; A. M. Osheiba

1989-01-01

88

Analytical Models for Polyphase Hysteresis Motor  

Microsoft Academic Search

Using parallelogram model to the B-H characteristic of the hysteresis material, general expressions for the terminal quantities of a polyphase hysteresis machine are derived. Steady-state equivalent circuit models are developed for both the synchronous and sub-synchronous modes of operation. A comprehensive analysis of rotor parasitic loss components and stator saturation effects is made and these are represented by suitable parameters

M. Azizur Rahman

1973-01-01

89

Equivalent Circuit Modeling of Hysteresis Motors  

SciTech Connect

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.

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

2009-08-31

90

Spatial versus time hysteresis in damping mechanisms  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

91

Hysteresis motor using magnetically anisotropic Fe-Cr-Co magnet  

Microsoft Academic Search

For the rotor ring of the hysteresis motor, semihard Alnico magnets have been almost applied until now. However, the hysteresis motor using Alnico magnets has several disadvantages. In order to improve the disadvantages of conventional hysteresis motors, the Fe-Cr-Co magnet steel with magnetic anisotropy is applied for hysteresis rotor ring. Magnetic anisotropy is used to cause large reluctance torque and

Tomotsugu Kubota; Genjiro Wakui; Minoru Itagaki

1998-01-01

92

Hysteresis effects of changing the parameters of noncooperative games  

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

93

Steady-State Performance of Polyphase Hysteresis-Reluctance Motors  

Microsoft Academic Search

It is well known that the hysteresis-reluctance motor produces a torque that is a combination of the hysteresis and reluctance effects. Consequently, the performance characteristics of a hysteresis-reluctance motor would be improved when compared to that of the plain hysteresis motor. This paper presents a new design of a hysteresis-reluctance rotor in which the magnetic saliency is created by cutting

M. A. Rahman; A. M. Osheiba

1986-01-01

94

Contact angle hysteresis generated by strong dilute defects.  

PubMed

Water on solid decorated with hydrophobic defects (such as micropillars) often stays at the top of the defects in a so-called fakir state, which explains the superhydrophobicity observed in such case, provided that the density of defects is small enough. Here we show that this situation provides an ideal frame for studying the contact angle hysteresis; the phase below the liquid is "perfect" and slippery (it is air), contrasting with pillars' tops whose edges form strong pining sites for the contact line. This model system thus allows us to study the hysteresis as a function of the density of defects and to compare it to the classical theory by Joanny and de Gennes, which is based on very similar hypothesis. PMID:19673137

Reyssat, Mathilde; Quéré, David

2009-03-26

95

Hysteresis Behaviors of Poly (Naphthalene Quinone) Radical Electrorheological Fluid  

NASA Astrophysics Data System (ADS)

As a potential electrorheological(ER) material, poly(naphthalene quinone) radical (PNQR) ER fluid was prepared, and its rheological behavior and hysteresis phenomenon were investigated. PNQR was synthesized by Friedel-Crafts acylation between naphthalene and phthalic anhydride, using zinc chloride as a catalyst at 256°C. A Physica rheometer equipped with a high voltage generator was used to measure the rheological properties of the ER fluids, which were prepared by dispersing PNQR in silicone oil at several particle concentrations. Shear stresses were observed to decrease as shear rate increased in the region of slow deformation rate. It was further found that ER fluid showed different hysteresis behaviors according to the shear rate ranges; thixotropy was observed in the low shear rate region (0.007-0.51/s) and anti-thixotropy in the high shear rate region (0.5-10001/s). Controlled shear stress mode was also applied to observe similar behaviors.

Choi, Hyoung J.; Cho, Min S.; Jhon, Myung S.

96

Hysteresis in the Central African Rainforest  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

97

Two-Dimensional Computational Fluid Dynamics Analysis of Hysteresis around Supersonic Biplane in Supersonic Flow  

NASA Astrophysics Data System (ADS)

The Busemann biplane is well known as the airfoil that has zero wave drag at the supersonic flight in the linear theory. It is found that this airfoil has a hysteresis in drag values from the transonic speeds through the low supersonic speeds based on Computational Fluid Dynamics (CFD) analysis. This paper shows that this hysteresis is explained by the Kantrowitz-Donaldson Criteria that usually defines the start and unstart of the supersonic intake.

Yonezawa, Masahito; Yamashita, Hiroshi; Obayashi, Shigeru; Kusunose, Kazuhiro

98

Influence of mounting on the hysteresis of polymer fiber Bragg grating strain sensors.  

PubMed

Fiber Bragg grating sensors recorded in poly(methyl methacrylate) fiber often exhibit hysteresis in the response of Bragg wavelength to strain, particularly when exposed to high levels of strain. We show that, when such a fiber grating sensor is bonded directly to a substrate, the hysteresis is reduced by more than 12 times, compared to the case where the sensor is suspended freely between two supports. PMID:23632489

Abang, Ada; Webb, David J

2013-05-01

99

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

100

Statistical mechanical origin of hysteresis in ferroelectrics  

NASA Astrophysics Data System (ADS)

Hysteresis in ferroelectric materials is a strong non-linear phenomenon, the origin of which has drawn considerable attention. Based on the hopping probability function of the lattice-center ion crossing the ferroelectric double-well potential, a statistical mechanical theory is proposed to model ferroelectric hysteresis behavior. The hopping probability function is obtained from the statistical distribution function of ions in energy space, which is derived from the mathematical permutation and combination of the occupy-states of lattice-center ion. The calculated hysteresis agrees well with experimental measurements. In particular, the model provides interesting explanations to the polarization current and the coercive field, which differ from traditional microscopic models and thermodynamic theories.

Yang, Feng; Hu, Guangda; Xu, Baixiang; Wu, Weibing; Yang, Changhong; Wu, Haitao

2012-08-01

101

Hysteresis and Wavenumber Vacillation in Unstable Baroclinic Flows  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

102

Effect of the Bering Strait on the AMOC hysteresis and glacial climate stability (Invited)  

NASA Astrophysics Data System (ADS)

Abrupt climate transitions, such as Dansgaard-Oeschger and Heinrich events, occurred frequently during the last glacial period, especially from 80 - 11 thousand years before present, but were nearly absent during Holocene and the early stages of last glacial period. Here we show, with a fully coupled climate model, that closing the Bering Strait and preventing its throughflow between the Pacific and Arctic Oceans during the glacial period can lead to the emergence of stronger hysteresis behavior of the Atlantic meridional overturning circulation (AMOC) to create conditions that are conducive to triggering abrupt climate transitions. Hence, it is argued that even for greenhouse warming, abrupt climate transitions similar to those in the last glacial time are unlikely to occur as the Bering Strait remains open. Qualitatively the same result is arrived in new simulations by employing the glacial background conditions using the same climate model. Theoretical and simulated AMOC hysteresis curves (a, b) and the associated changes of Greenland surface temperature and meridional heat transport at 65°N in the Atlantic (c, d). In panel a), 'S' is the bifurcation point beyond which AMOC collapses and the '+/-F' values indicate the freshwater forcing strength. In panels b), c), and d), the black/red (blue/green) lines are for the closed (open) BS simulation. The black/blue (red/green) lines represent the phase of freshwater forcing increase (decrease) in these simulations. Note that a change of the freshwater forcing by 0.1 Sv (Sv?106m3s-1) in this figure takes place over 500 model years.

Hu, A.; Meehl, G. A.; Han, W.; Timmermann, A.; Otto-Bliesner, B. L.; Liu, Z.; Abe-Ouchi, A.

2013-12-01

103

Curved Mirrors  

NSDL National Science Digital Library

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

Horton, Michael

2009-05-30

104

Parametric Curves parametric curves (Splines)  

E-print Network

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

Treuille, Adrien

105

AVERAGING PRINCIPLE FOR DIFFERENTIAL EQUATIONS WITH HYSTERESIS  

E-print Network

this approximation holds is inverse propor- tional to the rate of change of slow variables. The system is described on the systems with the classical Preisach nonlinearity. Key words: Averaging technique, Hysteresis, Sweeping to Boole Centre for Research in Informatics and Department of Applied Mathematics, University College Cork

Schellekens, Michel P.

106

The Hysteresis Motor with an Anisotropic Rotor  

Microsoft Academic Search

An analysis of the hysterezis motor with anisotropic rotor has been carried out. Using an elliptical approximation for the hysteresis loop, the expression of the magnetic vector potential in the anisotropic region of the rotor has been obtained both in the case of a stator surface carrying a curent sheet with sinusoidal variation, and in the case of a rotor

N. Galan

1987-01-01

107

AN ANALYSIS OF THE HYSTERESIS MOTOR  

Microsoft Academic Search

The analysis of the hysteresis motor Is undertaken on the basis of a “rectified” representation of its structure. Maxwell's equations and Poyntlng's theorem are used In order to obtain the dependency of the developed force on the physical parameters and dimensions of the machine. Three different limiting cases are studied and their characteristics computed

S. GAVRIL; A. MOR

1982-01-01

108

Hunting in hysteresis motors, impact of supply  

Microsoft Academic Search

Hunting in synchronous motor is the continuous speed oscillation with a frequency around 3 to 5 Hz which arises from voltage or load distortions. This oscillation descends with exponential trend-line to steady state relative lower amplitude. This paper presents an investigation of hunting when a synchronous hysteresis motor is supplied with non-ideal input voltage sources. For studying of machine performance

Ahmad Darabi; Mohamadreza Rafiei; Teimoor Ghanbari

2007-01-01

109

Equivalent Circuit Modeling of Hysteresis Motors.  

National Technical Information Service (NTIS)

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,...

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

2009-01-01

110

Circuit increases capability of hysteresis synchronous motor  

NASA Technical Reports Server (NTRS)

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.

Markowitz, I. N.

1967-01-01

111

Design of hysteresis circuits using differential amplifiers  

NASA Technical Reports Server (NTRS)

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

Cooke, W. A.

1971-01-01

112

Flexible pivot mount eliminates friction and hysteresis  

NASA Technical Reports Server (NTRS)

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.

Highman, C. O.

1970-01-01

113

Managing Hysteresis: Three Cornerstones to Fiscal Stability  

ERIC Educational Resources Information Center

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…

Weeks, Richard

2012-01-01

114

Rate-dependent hysteresis losses in ensembles of magnetic nanoparticle clusters  

NASA Astrophysics Data System (ADS)

Hysteresis is ubiquitous in magnetic nanoparticle systems and understanding how it emerges from complex interactions and for different time scales is a long-standing issue in magnetism research. Understanding the phenomenon is most important for engineering magnetic nanoparticle structures of well-controlled properties in magnetic recording, hysteresis loss optimization in hyperthermia cancer treatment in biomedicine, or biological and chemical sensing, to name a few examples. In this work we address one of the general questions related to the influence of thermal activation processes on hysteresis loss. Employing large-scale computational modeling based on the master-equation framework we investigate the influence of dipolar interactions on thermal hysteresis loops in ensembles of magnetic nanoparticle chains and clusters. We show that the directional dependence of dipolar interactions results in enhanced or reduced hysteresis loss, depending on the distribution of particles' anisotropy axes and particle chain orientations with respect to the external field. Additional hysteresis loss reduction occurs in case of particle clusters due to possibility of the frustration phenomenon not present for topologically simpler chains.

Hovorka, Ondrej; Evans, Richard; Friedman, Gary; Chantrell, Roy

2012-02-01

115

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

NASA Astrophysics Data System (ADS)

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

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

2008-06-01

116

Muscle hysteresis and movement control: a theoretical study.  

PubMed

In this study we have tried to elaborate necessary theoretical approaches for the adequate analysis of the central motor commands to a mammalian muscle in the equilibrium states and during transition movements between these states. At present, the equilibrium point hypothesis has obtained a wide distribution in this field. The muscle is considered in the framework of the theory as an executive element of the reflex circuits originating in the muscle proprioceptors and being closed at the level of spinal cord and the supraspinal motor centres. The main parameter defining the muscle state is supposed to be the threshold of the stretch reflex--the minimal length value at which muscle begins to resist to the externally applied force. We have attempted to show that the theory has an essential shortcoming because it does not take into account such important non-linearity in the muscle behaviour as hysteresis. In the framework of the equilibrium point hypothesis, the muscle behaviour within the stretch reflex system does not depend on movement direction. The stretch and unloading reflexes are supposed to have the same length tension dependencies when the muscle is stretching or contracting with a rather slow velocity. However, powerful hysteresis of the stretch reflex system requires taking into account the direction of the current movement, the after-effects of previous movement led to a principal uncertainty in the muscle steady-state. We would like to stress that any process of active muscle shortening should be controlled by dynamic components in efferent inflow. At the same time, the resulting steady-state develops by using effective hysteresis mechanism for its maintenance. The following hypothesis was proposed to explain the length clamping mechanisms in shortening transition movements. A significant decrement of the arrived efferent activity at the phase of the length fixation can evoke an internal elongation of the contractile elements within the muscle and corresponding hysteresis-like enhancement of the contractile effectiveness. Hence, instead of considering the quasi-static and dynamic components of movement commands as in the equilibrium point hypothesis, it is preferable to adopt a model of the shared coding of both the final position and movement velocity. The dynamic component of the efferent discharge seems to be required for a complete definition of the final steady-state, but maintenance of the state is closely associated with energetically advantageous hysteresis mechanisms. It was concluded that the dynamic phase of efferent activity should play an extremely important role in the central coding of the real movements produced, in particular, by contraction of agonists in the absence of antagonist activation. PMID:9466419

Kostyukov, A I

1998-03-01

117

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

NASA Astrophysics Data System (ADS)

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

Khoury, Charbel N.

118

Reduction of hysteresis in PI-controlled systems  

SciTech Connect

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

Krakow, K.I. [Concordia Univ., Montreal, Quebec (Canada). Dept. of Mechanical Engineering

1998-10-01

119

Extending hysteresis operators to spaces of piecewise continuous functions  

E-print Network

.D. MAWBY Department of Mathematical Sciences, University of Bath, Bath BA2 7AY, United Kingdom Email: hl@maths.bath.ac.uk, am@maths.bath.ac.uk Abstract: We consider continuous-time hysteresis operators, de#12;ned of \\hysteresis" loops. The memory e#11;ects exhibited by hysteresis phenomena are rate independent in contrast

Bath, University of

120

A Free Energy Model for Hysteresis in Ferroelectric Materials  

E-print Network

A Free Energy Model for Hysteresis in Ferroelectric Materials Ralph C. Smith Stefan Seelecke.ncsu.edu Abstract This paper provides a theory for quantifying the hysteresis and constitutive nonlinearities in#ects, and extreme electromechanical sensitivity, also produce varying degrees of hysteresis and constitutive

121

A Free Energy Model for Hysteresis in Ferroelectric Materials  

E-print Network

A Free Energy Model for Hysteresis in Ferroelectric Materials Ralph C. Smith Stefan Seelecke.ncsu.edu Abstract This paper provides a theory for quantifying the hysteresis and constitutive nonlinearities in, and extreme electromechanical sensitivity, also produce varying degrees of hysteresis and constitutive

122

Torque meter aids study of hysteresis motor rings  

NASA Technical Reports Server (NTRS)

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

Cole, M.

1967-01-01

123

Hysteresis in the trade cycle  

NASA Astrophysics Data System (ADS)

The Kaldor model-one of the first nonlinear models of macroeconomics-is modified to incorporate a Preisach nonlinearity. The new dynamical system thus created shows highly complicated behaviour. This paper presents a rigorous (computer aided) proof of chaos in this new model, and of the existence of unstable periodic orbits of all minimal periods p>57.

Mc Namara, Hugh A.; Pokrovskii, Alexei V.

2006-02-01

124

Basin of Attraction Determines Hysteresis in Explosive Synchronization  

NASA Astrophysics Data System (ADS)

Spontaneous explosive emergent behavior takes place in heterogeneous networks when the frequencies of the nodes are positively correlated to the node degree. A central feature of such explosive transitions is a hysteretic behavior at the transition to synchronization. We unravel the underlying mechanisms and show that the dynamical origin of the hysteresis is a change of basin of attraction of the synchronization state. Our findings hold for heterogeneous networks with star graph motifs such as scale-free networks, and hence, reveal how microscopic network parameters such as node degree and frequency affect the global network properties and can be used for network design and control.

Zou, Yong; Pereira, Tiago; Small, Michael; Liu, Zonghua; Kurths, Jürgen

2014-03-01

125

Basin of Attraction Determines Hysteresis in Explosive Synchronization  

E-print Network

Spontaneous explosive emergent behavior takes place in heterogeneous networks when the frequencies of the nodes are positively correlated to the node degree. A central feature of such explosive transitions is a hysteretic behavior at the transition to synchronization. We unravel the underlying mechanisms and show that the dynamical origin of the hysteresis is a change of basin of attraction of the synchronization state. Our findings hold for heterogeneous networks with star graph motifs such as scale free networks, and hence reveal how microscopic network parameters such as node degree and frequency affect the global network properties and can be used for network design and control.

Yong Zou; Tiago Pereira; Michael Small; Zonghua Liu; Jürgen Kurths

2014-01-07

126

Hysteresis effects of changing the parameters of noncooperative games.  

PubMed

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. PMID:22587144

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

2012-03-01

127

Origin of hysteresis in bed form response to unsteady flows  

NASA Astrophysics Data System (ADS)

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.

Martin, Raleigh L.; Jerolmack, Douglas J.

2013-03-01

128

Wetting Hysteresis at the Molecular Scale  

NASA Technical Reports Server (NTRS)

The motion of a fluid-fluid-solid contact line on a rough surface is well known to display hysteresis in the contact angle vs. velocity relationship. In order to understand the phenomenon at a fundamental microscopic level, we have conducted molecular dynamics computer simulations of a Wilhelmy plate experiment in which a solid surface is dipped into a liquid bath, and the force-velocity characteristics are measured. We directly observe a systematic variation of force and contact angle with velocity, which is single-valued for the case of an atomically smooth solid surface. In the microscopically rough case, however, we find (as intuitively expected) an open hysteresis loop. Further characterization of the interface dynamics is in progress.

Jin, Wei; Koplik, Joel; Banavar, Jayanth R.

1996-01-01

129

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

PubMed

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

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

2012-12-01

130

Lift hysteresis at stall as an unsteady boundary-layer phenomenon  

NASA Technical Reports Server (NTRS)

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

Moore, Franklin K

1956-01-01

131

Analytic synthesis of a hysteresis motor  

Microsoft Academic Search

This paper presents the unique synthesis of a motor with a hysteresis torque–speed characteristic. The machine is synthesized from a conventional polyphase squirrel cage induction motor (SCIM) with a high rotor resistance to leakage reactance r2\\/x2 ratio, which is mechanically coupled to a polyphase transfer field (TF) machine but with an inversion of the usual torque–speed characteristic of the latter

Linus U. Anih; Emeka S. Obe; Eugene O. Agbachi

2011-01-01

132

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

133

PC Based Pulsed Field Hysteresis Loop Tracer  

NASA Astrophysics Data System (ADS)

The present paper describes the design and setting up of a PC based hysteresis loop tracer that enables quick characterization of magnetic materials at room temperature. A high magnetic field is generated in a solenoid by passing a pulse current of sinusoidal shape at an interval slow enough to produce minimum heating in the solenoid. A pickup coil system is kept in the solenoid to detect field and magnetization signal of a sample placed in the pickup coil. These transitory analog signals are converted into digital signals by a micro-controller integrated circuit. These digital signals are sent to a computer through a serial port. A software has been developed to interface the system to the PC and processing the data to calculate hysteresis parameters like saturation magnetization Ms, coercivity Hc and remanence Mr followed by plotting of the hysteresis loop. The data and graphs can be printed or stored as files. The sample holder is designed for samples in powder or pellet form. The data acquired for some standard magnetic samples are presented.

Likhite, S. D.; Likhite, Prachi; Radha, S.

2011-07-01

134

Rheological Hysteresis in Soft Glassy Materials  

NASA Astrophysics Data System (ADS)

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.

Divoux, Thibaut; Grenard, Vincent; Manneville, Sébastien

2013-01-01

135

"The Show"  

ERIC Educational Resources Information Center

For the past 16 years, the blue-collar city of Huntington, West Virginia, has rolled out the red carpet to welcome young wrestlers and their families as old friends. They have come to town chasing the same dream for a spot in what many of them call "The Show". For three days, under the lights of an arena packed with 5,000 fans, the state's best…

Gehring, John

2004-01-01

136

Trapping and hysteresis in two-phase flow in porous media 2: Impact of pore-network model results on continuum scale models  

NASA Astrophysics Data System (ADS)

The parameters and parameter functions of classical formulations of two-phase flow in porous media - the relative permeability - saturation relationship, the capillary pressure - saturation relationship, and the associated residual saturations - show path dependence, i.e. their values depend not only on the state variables but also on their drainage and imbibition history. Many models incorporate these hysteretic effects through ad-hoc adaptations based on fitting curves to experimental data. In addition, various physically based models identify different pore-scale phenomena as crucial. They range from Preisach-type models for dependent or independent domains, to identifying new state variables - e.g. interfacial area or non-percolating fluid saturations - to resolve hysteresis. Several models identify trapping and connectivity of fluids as an important contribution to macro-scale hysteresis. This is especially true for hysteresis in relative permeabilities. The trapping models propose trajectories from the initial saturation to the end saturation in various ways and are based on experiments or pore-network model results for the endpoints. However, experimental data or pore-scale model results are not available for the trajectories, i.e. the fate of the connectivity of the fluids while saturation changes. Hence, a validation of the different models is yet to be accomplished. Here, the impact of new results from a quasi-static pore-network model study on the change of the topology of the fluids during drainage and imbibition (see abstract: Trapping and hysteresis in two-phase flow in porous media 1: Pore-network modeling) on continuum scale models is discussed. The pore-network model results are compared to continuum-scale relationships from the literature and the consequences for the hysteresis models in which they are incorporated are evaluated. We find that while the models predict the qualitative trends they do not capture several interesting phenomena like a bifurcation depending on the connectivity of the remaining non-wetting phase at the endpoints of imbibition When one drainage follows one imbibition, the difference in fluid distributions due to this bifurcation is moderate. However, if the process type changes frequently, like in alternating injection scenarios for CO2 sequestration, models that do not include this phenomenon may lead to wrong estimates of trapped CO2.

Doster, F.; Joekar-Niasar, V.; Nordbotten, J. M.; Celia, M. A.

2011-12-01

137

Sci Show  

NSDL National Science Digital Library

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

138

Mechano-electric optoisolator transducer with hysteresis  

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

139

Hysteresis prediction inside magnetic shields and application  

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

140

Effects of Hysteresis Between Maximum CME Speed Index and Typical Solar Activity Indicators During Cycle 23  

NASA Astrophysics Data System (ADS)

Using the smoothed time series of maximum CME speed index for solar cycle 23, it is found that this index, analyzed jointly with six other solar activity indicators, shows a hysteresis phenomenon. The total solar irradiance, coronal index, solar radio flux (10.7 cm), Mg ii core-to-wing ratio, sunspot area, and H? flare index follow different paths for the ascending and the descending phases of solar cycle 23, while a saturation effect exists at the maximum phase of the cycle. However, the separations between the paths are not the same for the different solar activity indicators used: the H? flare index and total solar irradiance depict broad loops, while the Mg ii core-to-wing ratio and sunspot area depict narrow hysteresis loops. The lag times of these indices with respect to the maximum CME speed index are discussed, confirming that the hysteresis represents a clue in the search for physical processes responsible for changing solar emission.

Özgüç, A.; Kilcik, A.; Rozelot, J. P.

2012-12-01

141

Terrestrial Exoplanet Light Curves  

E-print Network

The phase or orbital light curves of extrasolar terrestrial planets in reflected or emitted light will contain information about their atmospheres and surfaces complementary to data obtained by other techniques such as spectrosopy. We show calculated light curves at optical and thermal infrared wavelengths for a variety of Earth-like and Earth-unlike planets. We also show that large satellites of Earth-sized planets are detectable, but may cause aliasing effects if the lightcurve is insufficiently sampled.

Eric Gaidos; Nicholas Moskovitz; Darren M. Williams

2005-11-23

142

Hysteresis variations of (Pb, La)(Zr, Ti)O3 capacitors baked in a hydrogen atmosphere  

Microsoft Academic Search

Baking (Pb, La)(Zr, Ti)O3 capacitors in a hydrogen atmosphere causes a significant loss of remanent polarization even at 150 °C. The hysteresis variations depend on the polarization states during baking. The hysteresis loop showed voltage shifts when the capacitor was polarized before baking, whereas it became a cramped shape when the baking was carried out on a virgin capacitor. Although

T. Tamura; K. Matsuura; H. Ashida; K. Kondo; S. Otani

1999-01-01

143

Magnetic hysteresis behavior and microstructure of severely cold-worked and aged Co-Fe-Nb alloy  

Microsoft Academic Search

The magnetic hysteresis behavior of severely cold-worked and aged 85Co-12Fe-3Nb alloy was studied in relation to the microstructure. Magnetic hardening of the alloy can be attributed to the pinning of the domain wall by quasispherical Co3Nb precipitates. Alloys cold worked to 97.8% reduction in area and aged at 700, 800, and 900 °C showed the hysteresis behavior characteristic of inhomogeneous

Yuichi Suzuki; Masato Sagawa; Masanori Okada; Zenzo Henmi

1979-01-01

144

Adsorption kinetics in the solution of a thermal hysteresis protein  

NASA Astrophysics Data System (ADS)

According to the properties of the interactions between the thermal hysteresis proteins (THPs) and an ice crystal surface in the THP solution, we present a kinetic theory of the adsorption of thermal hysteresis proteins on the ice crystal surface. The thermal hysteresis activities of the THP solutions are given. The cooperative properties in the adsorption process of the THPs on the ice crystal surface are discussed.

Li, Qianzhong; Luo, Liaofu

2000-04-01

145

Curved Knives  

Microsoft Academic Search

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

W. F. Sinclair

1897-01-01

146

Effect of Air gap variation on characteristics of an Axial flux hysteresis motor  

Microsoft Academic Search

Axial flux hysteresis motor (AFHM) such as other types of hysteresis motor is self-starting synchronous motor that use the hysteresis characteristics of magnetic materials. It is known that the magnetic characteristics of hysteresis motor could be easily affected by air gap and structure dimensions variation. Air gap length plays an important role in flux distribution in hysteresis ring that can

Mohammad Modarres; Abolfazl Vahedi; Mohammadreza Ghazanchaei

2010-01-01

147

Efficient parameter estimation techniques for hysteresis models  

NASA Astrophysics Data System (ADS)

Actuators employing ferroelectric or ferromagnetic compounds are solid-state, efficient, and compact making them well-suited for aerospace, aeronautic, industrial and military applications. However, they also exhibit frequency, stress and thermally-dependent hysteresis and constitutive nonlinearities which must be incorporated in models for accurate device characterization and control design. A critical step in the use of these models is the estimation or re-estimation of parameters in a manner that is both efficient and robust. In this presentation, we discuss techniques to estimate densities in the homogenized energy model based on Galerkin expansions using physically motivated basis functions. The yields highly tractable optimization algorithms in which initial parameter estimates can be obtained from measured properties of the data. The efficiency and accuracy of the models and estimation algorithms are validated with experimental data.

Ernstberger, J. M.; Smith, R. C.

2009-03-01

148

A Hysteresis Model for Piezoceramic Materials  

NASA Technical Reports Server (NTRS)

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.

Smith, Ralph C.; Ounaies, Zoubeida

1999-01-01

149

Oscillatory activity in cells: multi-stability and hysteresis  

NASA Astrophysics Data System (ADS)

Oscillatory activity of cells has been the topic of many studies. Oscillatory activity can be due to action potential firing corresponding to the well-known Hodgkin-Huxley (HH) type dynamics of ion-channels in the cell membrane or due to IP3-mediated calcium oscillations in the endoplasmic reticulum (ER) causing periodic oscillations of calcium transients in the cytosol. In this study we show that coupling of these two oscillatory mechanisms may reveal a complex, rich spectrum of both stable and unstable states of cells with hysteresis. The predicted bi-stability corresponds to experimentally observed states. This illustrates that the different behavior of cells is not the consequence of differentiation in cells with different properties, but rather reflects different states of a single cell type.

Kusters, J. M. A. M.; Cortes, J. M.; van Meerwijk, W. P. M.; Ypey, D. L.; Theuvenet, A. P. R.; Gielen, C. C. A. M.

2007-02-01

150

Application of the Preisach model in soil-moisture hysteresis  

E-print Network

Application of the Preisach model in soil-moisture hysteresis Denis Flynn, Hugh McNamara, Philip O- teresis effects in the relation between water retention and soil-moisture ten- sion. Special, one parameter, classes of Preisach operators are proposed to construct models of the soil-moisture hysteresis

Schellekens, Michel P.

151

Friction and Adhesion Hysteresis between Surfactant Monolayers in Water  

E-print Network

Friction and Adhesion Hysteresis between Surfactant Monolayers in Water Wuge H. Briscoe Physical friction between two surfaces in adhesive contact with the loading­unloading adhesion hysteresis between them. We then examine in light of this model the observed low friction between two mica surfaces coated

Klein, Jacob

152

A Temperature-Dependent Hysteresis Model for Relaxor Ferroelectric Compounds  

E-print Network

subsequently incorporated the hysteretic low-temperature behavior through the development of domain wall modelsA Temperature-Dependent Hysteresis Model for Relaxor Ferroelectric Compounds Julie K. Raye- ature-dependent hysteresis and constitutive nonlinearities inherent to relaxor ferroelectric materials

153

A Domain Wall Theory for Ferroelectric Hysteresis Ralph C. Smith  

E-print Network

A Domain Wall Theory for Ferroelectric Hysteresis Ralph C. Smith Center for Research in Scienti c and control design, we consider a theory for ferroelectric hysteresis which is based on domain wall dynamics been recognized that domain and domain wall mechanisms within ferroelectric materi- als result

154

A Domain Wall Theory for Ferroelectric Hysteresis Ralph C. Smith  

E-print Network

A Domain Wall Theory for Ferroelectric Hysteresis Ralph C. Smith Center for Research in Scientific and control design, we consider a theory for ferroelectric hysteresis which is based on domain wall dynamics been recognized that domain and domain wall mechanisms within ferroelectric materi­ als result

155

Analysis and Determination of Ring Flux Distribution in Hysteresis Motors  

Microsoft Academic Search

This paper presents the results of an experimental determination of the flux distributions inside different layers of the hysteresis ring. The flux measurements were made by means of search coils embedded in the stationary ring of an inside-out three phase hysteresis motor. It is found that the flux distribution is quite nonuniform and there exist phase shift between the flux

R. D. Jackson; M. A. Rahman; G. R. Slemon

1983-01-01

156

Sensitivity analysis to the design parameters of a hysteresis motor  

Microsoft Academic Search

Hysteresis motors are mainly used for some applications that need very smooth torque from starting to synchronous speed such as gyroscope and gas centrifuge. This paper presents a sensitivity analysis of 60 W, 400 V, 6000 rpm super-high speed hysteresis motor characteristics including electromagnetic torque, power factor, efficiency and stator current to the design parameters including mechanical, electrical and magnetic

Abolfazl Halvaei Niasar; Hassan Moghbelli

2012-01-01

157

Magnetic equivalent circuit of PM hysteresis synchronous motor  

Microsoft Academic Search

This paper presents the magnetic equivalent circuit of a permanent magnet hysteresis synchronous motor (PMHS). The hybrid synchronous motor consists of 36% cobalt steel hysteresis alloys with neodymium iron boron permanent magnets to improve the overall performances of such a motor. Based on the magnetic equivalent circuit, the control strategy of the PMHS motor is developed. Experimental results confirm the

R. Qin; M. A. Rahman

2003-01-01

158

A permanent magnet hysteresis hybrid synchronous motor for electric vehicles  

Microsoft Academic Search

This paper presents the design, analysis and PWM vector control of a hybrid permanent magnet hysteresis synchronous (PMHS) motor with a view to improve the performances of motors for electric vehicle applications. This hybrid design combines the advantageous performance features of both conventional hysteresis motors and permanent magnet motors. Electrical equivalent circuits of the PMHS motor are developed for both

M. Azizur Rahman; Ruifeng Qin

1997-01-01

159

Starting and synchronization of permanent magnet hysteresis motors  

Microsoft Academic Search

This paper presents the design and application of permanent magnets in hysteresis motors with a view to improve the overall performances of such motors. The novel rotor consists of 36% cobalt steel alloys with neodymium boron iron permanent magnets. This hybrid design combines advantageous performance features of both typical permanent magnet motors and conventional hysteresis motors. Machine models for steady

M. A. Rahman; Ruifeng Qin

1994-01-01

160

Design of a compact hysteresis motor used in a gyroscope  

Microsoft Academic Search

In this paper, it presents the computer-aided design and test results of a compact hysteresis synchronous motor used as the drive motor of a gyroscope. Hysteresis motor is the best choice for this application because of its compactness and reliability. Also it has self-starting capability and it does not require any position sensor and communication circuits.

Rajagopal KR

2003-01-01

161

Starting and synchronization of permanent magnet hysteresis motors  

Microsoft Academic Search

This paper presents the design, analysis, and application of permanent magnets in a hysteresis motor with a view to improve the overall performance of such motors. The novel rotor consists of 36% cobalt steel alloys with neodymium boron iron permanent magnets. This hybrid design combines the advantageous performance features of both typical permanent magnet motors and conventional hysteresis motors. The

M. Azizur Rahman; Ruifeng Qin

1996-01-01

162

Magnetic equivalent circuit of PM hysteresis synchronous motor  

Microsoft Academic Search

This paper presents the magnetic equivalent circuit of a permanent magnet hysteresis synchronous (PMHS) motor. The hybrid synchronous motor consists of 30% Cobalt-steel hysteresis alloys Neodymium Iron Boron (NdFeB) permanent magnets to improve the overall performances of motors.

Ruifeng Qin; M. A. Rahman

2003-01-01

163

Analysis and Determination of Ring Flux Distribution in Hysteresis Motors  

Microsoft Academic Search

This paper presents the results of an experimental determination of the flux distributions inside different layers of the hysteresis ring. The flux measurements were made by means of search coils embedded in the stationary ring of an inside-out three phase hysteresis motor. It is found that the flux distribution is quite non-uniform and there exist phase shift between the flux

R. D. Jackson; M. A. Rahman; G. R. Slemon

1983-01-01

164

A permanent magnet hysteresis hybrid motor drive for electric vehicles  

Microsoft Academic Search

This paper presents the design, analysis and PWM vector control of a hybrid permanent magnet hysteresis synchronous motor with a view to improve the performances of the motors for electric vehicle application. This hybrid design combines the advantageous performance features of both the conventional hysteresis motors and the permanent magnet motors. A PWM vector control simulation and experimental results for

M. A. Rahman; Ruifeng Qin

1996-01-01

165

Performance simulation of hysteresis motors using accurate rotor media models  

Microsoft Academic Search

Recently, there has been an increased demand for small and medium sized brushless-type synchronous motors. Among these types, hysteresis motors have been especially used in those applications requiring precise speed and constant starting torque capabilities. In the past, several digital techniques for simulating the performance of hysteresis motors have been developed. These technique, however, involved significant approximations to the rotor

Amr A. Adly

1995-01-01

166

Impact of relative permeability hysteresis on geological CO2 storage  

Microsoft Academic Search

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

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

2006-01-01

167

Bistability and Hysteresis in the Organization of Apparent Motion Patterns  

Microsoft Academic Search

In a paradigm for which 2 distinct patterns are perceived for the same stimulus, perceptual hysteresis (persistence of a percept despite parameter change to values favoring the alternative pattern) and temporal stability (persistence despite intrinsic propensities toward spontaneous change) are interdependent. Greater persistence during parameter change reduces temporal stability, slowing the rate of parameter change reduces hysteresis by increasing opportunity

Howard S. Hock; J. A. Scott Kelso; Gregor Schöner

1993-01-01

168

Preisach modeling of piezoceramic and shape memory alloy hysteresis  

Microsoft Academic Search

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

Declan Hughes; John T. Wen

1995-01-01

169

Lumped-circuit models for nonlinear inductors exhibiting hysteresis loops  

Microsoft Academic Search

A new mathematical model of dynamic hysteresis loops is presented. The model is completely specified by two strictly monotonically increasing functions: a restoring function f(.) and a dissipation function g(.). Simple procedures are given for constructing these two functions so that the resulting model will simulate a given hysteresis loop exactly. The model is shown to exhibit many important hysteretic

L. Chua; K. Stromsmoe

1970-01-01

170

The Effect of Liquid Structure on Contact Angle Hysteresis.  

National Technical Information Service (NTIS)

Contact angle hysteresis was measured for a variety of liquids on condensed monolayers of 17-(perfluoroheptyl)-heptadecanoic acid adsorbed on polished chromium. The hysteresis was shown to be simply related to the molecular volume of the liquid and to res...

C. O. Timmons, W. A. Zisman

1966-01-01

171

Circuit measures hysteresis loop areas at 30 Hz  

NASA Technical Reports Server (NTRS)

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

Hoffman, C.; Spilo, D.

1967-01-01

172

Modeling Loading/Unloading Hysteresis Behavior of Unidirectional C/SiC Ceramic Matrix Composites  

NASA Astrophysics Data System (ADS)

The loading/unloading tensile behavior of unidirectional C/SiC ceramic matrix composites at room temperature has been investigated. The loading/unloading stress-strain curve exhibits obvious hysteresis behavior. An approach to model the hysteresis loops of ceramic matrix composites including the effect of fiber failure during tensile loading has been developed. By adopting a shear-lag model which includes the matrix shear deformation in the bonded region and friction in the debonded region, the matrix cracking space and interface debonded length are obtained by matrix statistical cracking model and fracture mechanics interface debonded criterion. The two-parameter Weibull model is used to describe the fiber strength distribution. The stress carried by the intact and fracture fibers on the matrix crack plane during unloading and subsequent reloading is determined by the Global Load Sharing criterion. Based on the damage mechanisms of fiber sliding relative to matrix during unloading and subsequent reloading, the unloading interface reverse slip length and reloading interface new slip length are obtained by the fracture mechanics approach. The hysteresis loops of unidirectional C/SiC ceramic matrix composites corresponding to different stress have been predicted.

Longbiao, Li; Yingdong, Song; Youchao, Sun

2013-08-01

173

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

Microsoft Academic Search

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

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

1992-01-01

174

Quantification of Hysteresis and Nonlinear Effects on the Frequency Response of Ferroelectric and  

E-print Network

Quantification of Hysteresis and Nonlinear Effects on the Frequency Response of Ferroelectric. However, these materials also exhibit hysteresis and constitutive nonlinearities at all drive levels of hysteresis and nonlinearities on the frequency behavior of devices that employ these compounds. Whereas

175

Control of Hysteresis in Smart Actuators. Part 1. Modeling, Parameter Identification, and Inverse Control.  

National Technical Information Service (NTIS)

Hysteresis in smart actuators presents a challenge in control of these actuators. A fundamental idea to cope with hysteresis is inverse compensation. In this paper we study modeling, identification and inverse control of hysteresis in smart actuators thro...

X. Tan, J. S. Baras

2002-01-01

176

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

PubMed

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

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

2012-08-01

177

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

NASA Astrophysics Data System (ADS)

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

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

178

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

NASA Astrophysics Data System (ADS)

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.

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

2012-08-01

179

A constitutive model for the frequency dependence of magnetic hysteresis  

NASA Astrophysics Data System (ADS)

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

Ho, Kwangsoo

2014-10-01

180

Static measurements of slender delta wing rolling moment hysteresis  

NASA Technical Reports Server (NTRS)

Slender delta wing planforms are susceptible to self-induced roll oscillations due to aerodynamic hysteresis during the limit cycle roll oscillation. Test results are presented which clearly establish that the static rolling moment hysteresis has a damping character; hysteresis tends to be greater when, due to either wing roll or side slip, the vortex burst moves back and forth over the wing trailing edge. These data are an indirect indication of the damping role of the vortex burst during limit cycle roll oscillations.

Katz, Joseph; Levin, Daniel

1991-01-01

181

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

182

[Mathematical models of hysteresis]. Progress report No. 4, [January 1, 1991--December 31, 1991  

SciTech Connect

The research described in this proposal is currently being supported by the US Department of Energy under the contract ``Mathematical Models of Hysteresis``. Thus, before discussing the proposed research in detail, it is worthwhile to describe and summarize the main results achieved in the course of our work under the above contract. Our ongoing research has largely been focused on the development of mathematical models of hysteretic nonlinearities with ``nonlocal memories``. The distinct feature of these nonlinearities is that their current states depend on past histories of input variations. It turns out that memories of hysteretic nonlinearities are quite selective. Indeed, experiments show that only some past input extrema leave their marks upon future states of hysteretic nonlinearities. Thus special mathematical tools are needed in order to describe nonlocal selective memories of hysteretic nonlinearities. Our research has been primarily concerned with Preisach-type models of hysteresis. All these models have a common generic feature; they are constructed as superpositions of simplest hysteretic nonlinearities-rectangular loops. Our study has by and large been centered around the following topics: various generalizations and extensions of the classical Preisach model, finding of necessary and sufficient conditions for the representation of actual hysteretic nonlinearities by various Preisach type models, solution of identification problems for these models, numerical implementation and experimental testing of Preisach type models. Although the study of Preisach type models has constituted the main direction of the research, some effort has also been made to establish some interesting connections between these models and such topics as: the critical state model for superconducting hysteresis, the classical Stoner-Wohlfarth model of vector magnetic hysteresis, thermal activation type models for viscosity, magnetostrictive hysteresis and neural networks.

Mayergoyz, I.D.

1991-12-31

183

On the question of hysteresis in Hall magnetohydrodynamic reconnection  

SciTech Connect

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.

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

184

Hysteresis as a Marker for Complex, Overlapping Landscapes in Proteins  

PubMed Central

Topologically complex proteins fold by multiple routes as a result of hard-to-fold regions of the proteins. Oftentimes these regions are introduced into the protein scaffold for function and increase frustration in the otherwise smooth-funneled landscape. Interestingly, while functional regions add complexity to folding landscapes, they may also contribute to a unique behavior referred to as hysteresis. While hysteresis is predicted to be rare, it is observed in various proteins, including proteins containing a unique peptide cyclization to form a fluorescent chromophore as well as proteins containing a knotted topology in their native fold. Here, hysteresis is demonstrated to be a consequence of the decoupling of unfolding events from the isomerization or hula-twist of a chromophore in one protein and the untying of the knot in a second protein system. The question now is- can hysteresis be a marker for the interplay of landscapes where complex folding and functional regions overlap? PMID:23525263

Andrews, Benjamin T.; Capraro, Dominique T.; Sulkowska, Joanna I.; Onuchic, Jose N.; Jennings, Patricia A.

2013-01-01

185

Contact angle hysteresis: a review of fundamentals and applications  

E-print Network

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 ...

’t Mannetje, D. J. C. M.

186

Dynamic wetting on superhydrophobic surfaces: Droplet impact and wetting hysteresis  

E-print Network

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 ...

Smyth, Katherine M.

187

A high-speed hysteresis motor spindle for machining applications  

E-print Network

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 ...

Bayless, Jacob D. (Jacob Daniel)

2014-01-01

188

Low-Hysteresis Flow-Through Wind-Tunnel Balance  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

189

Hysteresis in Thin-Film Rechargeable Lithium Batteries  

SciTech Connect

Discharge - charge cycling of thin-film rechargeable lithium batteries with an amorphous or nanocrystalline LiXMn2.Y04 cathode reveals evidence for a true hysteresis in the lithium insertion reaction. This is compared with an apparent hysteresis attributed to a kinetically hindered phase transition near 3 V for batteries with either a crystalline or a nanocrystalline LiJ@Yo4 cathode.

Bates, J.B.; Dudney, N.J.; Evans, C.D.; Hart, F.X.

1999-04-25

190

Design of a compact hysteresis motor used in a gyroscope  

Microsoft Academic Search

This paper presents the computer-aided design and test results of a compact three-phase hysteresis synchronous motor used as the drive motor of a gyroscope. Hysteresis motor is the best choice for this application because of its compactness and reliability. Also, it has a self-starting capability and it does not require any position sensor and commutation circuits. The design of a

K. R. Rajagopal

2003-01-01

191

Transient performance analysis for permanent-magnet hysteresis synchronous motor  

Microsoft Academic Search

The combination of hysteresis and permanent-magnet materials in the rotor of a self-starting synchronous motor makes the motor analysis very difficult due to its inherent nonlinearity. This paper presents the simulation results of the transient performance of permanent magnet hysteresis synchronous (PMHS) motors. The major feature in this study is to combine the time-stepping finite-element technique with the model for

Kazumi Kurihara; M. Azizur Rahman

2004-01-01

192

Stabilization of supercooled fluids by thermal hysteresis proteins.  

PubMed Central

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

Wilson, P W; Leader, J P

1995-01-01

193

Hysteresis as an implicit prior in tactile spatial decision making.  

PubMed

Perceptual decisions not only depend on the incoming information from sensory systems but constitute a combination of current sensory evidence and internally accumulated information from past encounters. Although recent evidence emphasizes the fundamental role of prior knowledge for perceptual decision making, only few studies have quantified the relevance of such priors on perceptual decisions and examined their interplay with other decision-relevant factors, such as the stimulus properties. In the present study we asked whether hysteresis, describing the stability of a percept despite a change in stimulus property and known to occur at perceptual thresholds, also acts as a form of an implicit prior in tactile spatial decision making, supporting the stability of a decision across successively presented random stimuli (i.e., decision hysteresis). We applied a variant of the classical 2-point discrimination task and found that hysteresis influenced perceptual decision making: Participants were more likely to decide 'same' rather than 'different' on successively presented pin distances. In a direct comparison between the influence of applied pin distances (explicit stimulus property) and hysteresis, we found that on average, stimulus property explained significantly more variance of participants' decisions than hysteresis. However, when focusing on pin distances at threshold, we found a trend for hysteresis to explain more variance. Furthermore, the less variance was explained by the pin distance on a given decision, the more variance was explained by hysteresis, and vice versa. Our findings suggest that hysteresis acts as an implicit prior in tactile spatial decision making that becomes increasingly important when explicit stimulus properties provide decreasing evidence. PMID:24587045

Thiel, Sabrina D; Bitzer, Sebastian; Nierhaus, Till; Kalberlah, Christian; Preusser, Sven; Neumann, Jane; Nikulin, Vadim V; van der Meer, Elke; Villringer, Arno; Pleger, Burkhard

2014-01-01

194

Hysteresis as an Implicit Prior in Tactile Spatial Decision Making  

PubMed Central

Perceptual decisions not only depend on the incoming information from sensory systems but constitute a combination of current sensory evidence and internally accumulated information from past encounters. Although recent evidence emphasizes the fundamental role of prior knowledge for perceptual decision making, only few studies have quantified the relevance of such priors on perceptual decisions and examined their interplay with other decision-relevant factors, such as the stimulus properties. In the present study we asked whether hysteresis, describing the stability of a percept despite a change in stimulus property and known to occur at perceptual thresholds, also acts as a form of an implicit prior in tactile spatial decision making, supporting the stability of a decision across successively presented random stimuli (i.e., decision hysteresis). We applied a variant of the classical 2-point discrimination task and found that hysteresis influenced perceptual decision making: Participants were more likely to decide ‘same’ rather than ‘different’ on successively presented pin distances. In a direct comparison between the influence of applied pin distances (explicit stimulus property) and hysteresis, we found that on average, stimulus property explained significantly more variance of participants’ decisions than hysteresis. However, when focusing on pin distances at threshold, we found a trend for hysteresis to explain more variance. Furthermore, the less variance was explained by the pin distance on a given decision, the more variance was explained by hysteresis, and vice versa. Our findings suggest that hysteresis acts as an implicit prior in tactile spatial decision making that becomes increasingly important when explicit stimulus properties provide decreasing evidence. PMID:24587045

Thiel, Sabrina D.; Bitzer, Sebastian; Nierhaus, Till; Kalberlah, Christian; Preusser, Sven; Neumann, Jane; Nikulin, Vadim V.; van der Meer, Elke; Villringer, Arno; Pleger, Burkhard

2014-01-01

195

Aileron roll hysteresis effects on entry of space shuttle orbiter  

NASA Technical Reports Server (NTRS)

Six-degree-of-freedom simulations of the space shuttle orbiter entry with control hysteresis were conducted on the NASA Langley Research Center interactive simulator known as the automatic reentry flight dynamics simulator. These simulations revealed that the vehicle can tolerate control hysteresis producing a + or - 50 percent change in the nominal aileron roll characteristics and an offset in the nominal characteristics equivalent to a + or - 5 deg aileron deflection with little increase in the reaction control system's fuel consumption.

Powell, R. W.

1977-01-01

196

Compensator design for hysteresis of a stacked PZT actuator using a congruency-based hysteresis model  

NASA Astrophysics Data System (ADS)

This paper proposes a rate-independent hysteresis compensator for a stacked PZT (lead zirconate titanate) actuator. From a congruency-based hysteresis (CBH) model which is derived from the inherent properties of this actuator, especially the congruency, a feedforward compensator associated with it is developed. The formulation of the proposed compensator is based on an assumption that the inverse operator also possesses the same properties as the CBH model does. This implies that the compensator also possesses properties such as the wiped-out loop closing between the consecutive control points and congruency. Consequently, the expressions for the compensator can be conducted by exploiting the equations for the CBH model in two cases of monotonic increase and monotonic decrease of input excitation. In order to assess the performance of the compensator, several experiments in both open-loop and closed-loop controls are undertaken. In the open-loop control experiment, the performance of the feedforward compensator using the CBH model is compared with the classical Preisach model-based one in three cases of reference waveforms. In the closed-loop control experiment, the proposed compensator is incorporated into a PID (proportional-integral-derivative) control system and the performance of this integrated system is then evaluated and compared to that of the PID with and without compensator.

Nguyen, Phuong-Bac; Choi, Seung-Bok

2012-01-01

197

The hysteresis motor-advances whick permit economical fractional horsepower ratings  

Microsoft Academic Search

The theory of the development of torque in a hysteresis motor is analyzed from both the hysteresis lag angle and total loop energy points of view. A new development, comprising the use of a closed slot stator in co-operation with a hysteresis rotor, which permits building hysteresis motors of high power output at high efficiency is explained qualitatively and supplemented

Herbert C. Roters

1947-01-01

198

Torque computation of hysteresis motor using finite element analysis with asymmetric two dimensional magnetic permeability tensor  

Microsoft Academic Search

This paper deals with the analysis of the generated torque of the hysteresis motor using finite element method, The material property of the hysteresis ring in the hysteresis motor is characterized by the asymmetric two dimensional magnetic permeability tensor. The torque has been computed effectively by using permeability tensor instead of full hysteresis modeling or Maxwell stress tensor. The proposed

Hak-Yong Lee; Song-Yop Hahn; Gwan-Soo Park; Ki-Sik Lee

1998-01-01

199

Optimization of a new type of hysteresis motor using genetic algorithm  

Microsoft Academic Search

HYSTERESIS motors are self-starting synchronous motors that take advantage of the hysteresis characteristics of the magnetic materials. Robust structure, flat speed-torque characteristics, smooth operation and constant low starting current are the outstanding specifications of these machines. Nevertheless, low efficiency and low power factor are among the disadvantages of common hysteresis motors. Very recently, Coreless Dual Discs Hysteresis Motor (CDDHM) has

M. H. Sadeghi; A. Darabi

2010-01-01

200

Curves and Their Properties.  

ERIC Educational Resources Information Center

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,…

Yates, Robert C.

201

Steady-State Performance Analysis of Polyphase Hysteresis-Reluctance Motors  

Microsoft Academic Search

It is well-known that the hysteresis-reluctance motor produces a torque that is a combination of the hysteresis and reluctance effects. Consequently, the performance characteristics of a hysteresis-reluctance motor would be improved when compared to that of the plain hysteresis motor. A new design of a hysteresis-reluctance rotor is presented in which the magnetic saliency is created by cutting slots in

M. Azizur Rahman; Ali M. Osheiba

1985-01-01

202

Archimedes Curves  

ERIC Educational Resources Information Center

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.

Swain, Gordon A.

2013-01-01

203

Simulation of a vector hysteresis measurement system taking hysteresis into account by the vector Preisach model  

NASA Astrophysics Data System (ADS)

The paper deals with the numerical analysis of a rotational single sheet tester with round-shaped specimen (RRSST) which is now under construction. The measurement setup consists of an induction motor the rotor of which has been removed, and its windings have been replaced to a special two phase one which can generate homogeneous magnetic field inside the motor. The two orthogonal components of the magnetic field intensity and of the magnetic flux density vectors can be measured by H-coils and B-coils, respectively. The Finite Element Method (FEM) with the T, ?-? potential formulation has been applied in the simulations. The vector hysteresis property of the specimen has been approximated by the vector Preisach model. Finally, the nonlinear problem has been solved by the fixed-point technique. The aim of the present work is to focus on the design aspects of this kind of measurement system.

Kuczmann, Miklós

2008-02-01

204

Magnetic Study of Martensitic Transformation in Austenitic Stainless Steel by Low Field Hysteresis Loops Analysis  

SciTech Connect

Magnetic method has been used to evaluate the volume percentage of {alpha}' martensitic phase in austenitic stainless steels by measuring saturation magnetization, and it is said to be a candidate NDE method. However, nondestructive detection of saturation magnetization without high magnetic field is difficult. In the current work, we present a NDE method for evaluating the magnetic properties of strain induced {alpha}' martensitic phase. Low field hysteresis loops of an austenitic stainless steels type SUS 304 after cold rolling were measured by using a yoke sensor. The results show that the initial permeability {mu}i and the relative coercive field Hcl calculated by low field hysteresis loop analysis keep monotonic relation with saturation magnetization and coercive force measured by VSM, respectively. By this method, it is possible to characterize the volume content and particle properties of {alpha}' martensitic phase in stainless steels.

Zhang Lefu; Takahashi, Seiki; Kamada, Yasuhiro; Kikuchi, Hiroaki; Mumtaz, Khalid; Ara, Katsuyuki; Sato, Masaya [NDE Center, Faculty of Engineering, Iwate University, Morioka, 020-8551 (Japan)

2005-04-09

205

Polarization-dependent asymmetric hysteresis behavior in ZnCrO layers  

NASA Astrophysics Data System (ADS)

A ZnCrO layer grown on a Pt (111)/Al2O3 (0001) substrate exhibits a lattice displacement-induced ferroelectric behavior due to a modulation in the lattice translation symmetry. The top-to-bottom Pt/ZnCrO/Pt structure shows asymmetric hysteresis loops in positive and negative voltage bias regions. This is attributed to a change in the Schottky emission rate due to the nonlinear polarization of the ZnCrO barrier. The characteristics of the hysteresis loops depend on the film-textures of ZnCrO, which vary with the oxygen partial pressure during the growth stage of the ZnCrO layers. The results suggest that ZnCrO has efficacy characteristics for applications in the non-volatile resistive-switching systems.

Lee, Youngmin; Kim, Deuk Young; Lee, Sejoon; Fu, Dejun

2012-06-01

206

Microstructures in Low-Hysteresis Shape Memory Alloys: Scaling Regimes and Optimal Needle Shapes  

NASA Astrophysics Data System (ADS)

For certain martensitic phase transformations, one observes a close relation between the width of the thermal hysteresis and the compatibility of two phases. This observation forms the basis of a theory of hysteresis that assigns an important role to the microstructures in the transition layer and their energetics (Zhang et al., Acta Mater 57(15), 4332-4352, 2009). We study microstructures for almost compatible phases in the context of nonlinear elasticity. Using a scalar valued ansatz we show that one expects a transition from uniform to branched patterns for various typical models of the surface energy. We subsequently consider needle-type transition layers and study quantitative differences between hard and soft austenite, and between twins of different martensitic variants.

Zwicknagl, Barbara

2014-08-01

207

Impact of capillary hysteresis and trapping on vertically integrated models for CO2 storage  

NASA Astrophysics Data System (ADS)

Vertically integrated models are frequently applied to study subsurface flow related to CO2 storage scenarios in saline aquifers. In this paper, we study the impact of capillary-pressure hysteresis and CO2 trapping on the integrated constitutive parameter functions. Our results show that for the initial drainage and a subsequent imbibition, trapping is the dominant contributor to hysteresis in integrated models. We also find that for advective processes like injection and plume migration in a sloped aquifer the correct treatment of the hysteretic nature of the capillary fringe is likely of secondary importance. However, for diffusive/dispersive processes such as a redistribution of the CO2 plume due to buoyancy and capillary forces, the hysteretic nature of the capillary fringe may significantly impact the final distribution of the fluids and the timescale of the redistribution.

Doster, F.; Nordbotten, J. M.; Celia, M. A.

2013-12-01

208

Magnetic hysteresis of p(+) and He-3(2+) irradiated melt-textured YBa2Cu3O(7-delta)  

NASA Technical Reports Server (NTRS)

We have measured the magnetic hysteresis loops and temperature dependent trapped fields in melt-textured YBa2Cu3O(7-delta) samples before and after p(+) and He-3(2+) irradiation using a Hall effect magnetometer (HEM) as well as a commercial vibrating sample magnetometer (VSM). For proper He-3(2+) fluence, the critical current density may be enhanced by a factor of 10. Calculations based on various critical state models show that before the irradiation, the hysteresis loops can be well accounted for by a critical current density of a modified power law field dependence. After the irradiation, the best fit has been achieved by using an exponential form. Jc and its field dependence deduced from HEM hysteresis loops are in good agreement with those deduced from the VSM loops, suggesting that the Hall effect magnetometer can be conveniently used to characterize bulk high Tc oxide superconductors.

Song, S. N.; Liu, J.; Chen, I. G.; Weinstein, Roy

1992-01-01

209

Steady-state and unsteady-state two-phase relative permeability hysteresis and measurements of three-phase relative permeabilities using imaging techniques  

SciTech Connect

The objective of this work is to improve determination of two-phase and three-phase relative permeabilities by the use of saturation imaging techniques. The first part of the paper reports on steady-state and unsteady-state relative permeability experiments performed on restored-state carbonate reservoir cores. The aim was to study how relative permeability test methodology impacts relative permeability curves. hysteresis and residual oil saturations in these intermediate-wet cores. Refined oil was used. Significant hysteresis was observed in both the unsteady-state water and oil relative permeabilities. The characteristics of the unsteady-state water relative permeabilities imply that viscous instabilities were present during the waterflood. Centrifuge capillary pressure-wettability tests performed on companion core plugs both before and after the relative permeability tests showed good agreement with the unsteady-state results, but indicated change towards less oil-wetness during the steady-state tests. The main conclusion of this work is that extensive flushing of a restored-state core with refined oil may lead to a non representative relative permeability data and should therefore be avoided. The second part of the paper presents a summary of results obtained from three-phase unsteady-state flow in water-wet sandstone (Berea and Clashach) cores. In-situ saturation measurements show that the water relative permeability is dependent on water saturation alone, and that there is no change in water relative permeability due to three-phase flow. The waterflood residual oil saturation was found reduced in the presence of a gas phase, and may depend on the phase (oil or gas) injected prior to waterflooding.

Eleri, O.O.; Graue, A; Akauge, A.

1995-12-31

210

Thermodynamic Model for Contact Angle Hysteresis on Rough Surfaces  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

211

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

SciTech Connect

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.

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

212

Quotient curves of the GK curve  

E-print Network

For every $q=l^3$ with $l$ a prime power greater than 2, the GK curve $X$ is an $F_{q^2}$-maximal curve that is not $F_{q^2}$-covered by any $F_{q^2}$-maximal Deligne-Lusztig curve. Interestingly, $X$ has a very large $F_{q^2}$-automorphism group with respect to its genus. In this paper we compute the genera of a large variety of curves that are Galois-covered by the GK curve, thus providing several new values in the spectrum of genera of $F_{q^2}$-maximal curves.

Giulietti, Stefania Fanali; Massimo

2009-01-01

213

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

NASA Astrophysics Data System (ADS)

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.

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

2008-01-01

214

PREFACE: International Workshop on Multi-Rate Processes and Hysteresis  

NASA Astrophysics Data System (ADS)

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

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

2008-07-01

215

Linear systems on tropical curves  

Microsoft Academic Search

A tropical curve ? is a metric graph with possibly unbounded edges, and tropical rational functions are continuous piecewise\\u000a linear functions with integer slopes. We define the complete linear system |D| of a divisor D on a tropical curve ? analogously to the classical counterpart. We investigate the structure of |D| as a cell complex and show that linear systems

Christian Haase; Gregg Musiker; Josephine Yu

216

Hysteresis in the production of force by larval Dipteran muscle.  

PubMed

We describe neuromuscular hysteresis - the dependence of muscle force on recent motoneuron activity - in the body wall muscles of larval Sarcophaga bullata and Drosophila melanogaster. In semi-intact preparations, isometric force produced by a train of nerve impulses at a constant rate was significantly less than that produced by the same train of stimuli with a brief (200 ms) high-frequency burst of impulses interspersed. Elevated force did not decay back to predicted values after the burst but instead remained high throughout the duration of the stimulus train. The increased force was not due to a change in excitatory junction potentials (EJPs); EJP voltage and time course before and after the high-frequency burst were not statistically different. Single muscle and semi-intact preparations exhibited hysteresis similarly, suggesting that connective tissues of the origin or insertion are not crucial to the mechanism of hysteresis. Hysteresis was greatest at low motoneuron rates - yielding a approximately 100% increase over predicted values based on constant-rate stimulation alone - and decreased as impulse rate increased. We modulated motoneuron frequency rhythmically across rates and cycle periods similar to those observed during kinematic analysis of larval crawling. Positive force hysteresis was also evident within these more physiological activation parameters. PMID:20581278

Paterson, Bethany A; Anikin, Ilya Marko; Krans, Jacob L

2010-07-15

217

Journal of Instruction-Level Parallelism 5(2003) 1-32 Submitted 2/02; published 6/03 Exploiting Bias in the Hysteresis Bit of 2-bit Saturating Counters in  

E-print Network

in most branch predictor designs. Smith observed that using two bits per counter yields better predictor Bias in the Hysteresis Bit of 2-bit Saturating Counters in Branch Predictors Gabriel H. Loh LOH branch predictors. We show that counters exhibit a strong bias in the hysteresis bit as well, suggesting

Krishnamurthy, Arvind

218

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

219

Trapping and hysteresis in two-phase flow in porous media: A pore-network study  

NASA Astrophysics Data System (ADS)

Several models for two-phase flow in porous media identify trapping and connectivity of fluids as an important contribution to macroscale hysteresis. This is especially true for hysteresis in relative permeabilities. The trapping models propose trajectories from the initial saturation to the end saturation in various ways and are often based on experiments or pore-network model results for the endpoints. However, experimental data or pore-scale model results are often not available for the trajectories, that is, the fate of the connectivity of the fluids while saturation changes. Here, using a quasi static pore-network model, supported by a set of pore-scale laboratory experiments, we study how the topology of the fluids changes during drainage and imbibition including first, main and scanning curves. We find a strong hysteretic behavior in the relationship between disconnected nonwetting fluid saturation and the wetting fluid saturation in a water-wet medium. The coalescence of the invading nonwetting phase with the existing disconnected nonwetting phase depends critically on the presence (or lack thereof) of connected nonwetting phase at the beginning of the drainage process as well as on the pore geometry. This dependence involves a mechanism we refer to as "reversible corner filling." This mechanism can also be seen in laboratory experiments in volcanic tuff. The impact of these pore-network model results on existing macroscopic models is discussed.

Joekar-Niasar, V.; Doster, F.; Armstrong, R. T.; Wildenschild, D.; Celia, M. A.

2013-07-01

220

A Fluid Mechanical Interpretation of Hysteresis in Rhinomanometry  

PubMed Central

A hysteresis effect in the pressure/flow rate relationship of nasal breathing has frequently been observed in clinical tests and in lab investigations. Explanations that have been given in the literature are missing a fluid mechanic storage effect coming into play in reciprocating flows. This effect depends primarily on the way the rhinomanometric measurements are set up and not so much on the nose flow itself. This is to be shown by calculations and experiments. The experiments are carried out with orifices because they can represent nose flow and are often implemented in rhinomanometric equipment as flow gauges. To mimic reality also a 1?:?1 nose model is used. It is shown where the hysteresis comes from and what the key parameters for its prediction are. With these results hysteresis in nasal breathing appears in a new light. PMID:23724249

Gross, T. F.; Peters, F.

2011-01-01

221

The apparent hysteresis in hormone-agonist relationships  

PubMed Central

It has been noted in multiple studies that the calcium–PTH axis, among others, is subject to an apparent hysteresis. We sought to explain a major component of the observed phenomenon by constructing a simple mathematical model of a hormone and secretagogue system with concentration dependent secretion and containing two delays. We constructed profiles of the hormone–agonist axis in this model via four types of protocols, three of which emulating experiments from the literature, and observed a delay- and load-dependent hysteresis that is an expected mathematical artifact of the system described. In particular, the delay associated with correction allows for over-secretion of the hormone influencing the corrective mechanism; thus rate dependence is an artifact of the corrective mechanism, not a sensitivity of the gland to the magnitude of change. From these observations, the detected hysteresis is due to delays inherent in the systems being studied, not in the secretory mechanism. PMID:22154846

Pruett, William A.; Hester, Robert L.; Coleman, Thomas G.

2011-01-01

222

A modified Prandtl-Ishlinskii modeling method for hysteresis  

NASA Astrophysics Data System (ADS)

A modified Prandtl-Ishlinskii modeling method for rate-independent hysteresis in piezoelectric actuators is proposed in this paper. In this method, a generalized backlash operator (GBO) regarded as the elementary operator is introduced into the model so as to be more flexible for modeling of complex hysteresis. Moreover, the Levenberg-Marquardt algorithm is used to estimate the parameters of the model. Thus, all the parameters of the modified PI model can be determined automatically. From this way, it avoids the tedious procedure for the selection of the operator parameters by trial and error. Then, a group of proper Clarke subgradients of the GBO outputs with respect to their parameters at a non-smooth point is obtained based on the bundle method. Finally, the experimental results of applying the proposed method to the modeling of hysteresis in a piezoelectric actuator and an ultrasonic motor (USM) are illustrated, respectively.

Dong, Ruili; Tan, Yonghong

2009-05-01

223

Saturation overshoot and hysteresis for twophase flow in porous media  

NASA Astrophysics Data System (ADS)

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.

Hilfer, R.; Steinle, R.

2014-10-01

224

Unconventional dynamic hysteresis in a periodic assembly of paramagnetic colloids.  

PubMed

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

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

2013-06-01

225

Contact Hysteresis and Friction of Alkanethiol SAMs on Au  

SciTech Connect

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

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

1998-10-14

226

An Energy-Based Hysteresis Model for Magnetostrictive Transducers  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

227

Sinusoidal input describing function for hysteresis followed by elementary backlash  

NASA Technical Reports Server (NTRS)

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

Ringland, R. F.

1976-01-01

228

Hysteresis Modeling in Magnetostrictive Materials Via Preisach Operators  

NASA Technical Reports Server (NTRS)

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.

Smith, R. C.

1997-01-01

229

Standard Mastery Curves and Skew Curves.  

ERIC Educational Resources Information Center

The objective of the study is to convince educational researchers of the necessity for "standard mastery curves" for the graphical representation of scores on summative tests for a group of students. Attention is drawn to the study of theoretical and empirical skew curves in education and biology. Use of standard mastery curves and study of skew…

Warries, Egbert

230

Thin films of spin-crossover coordination polymers with large thermal hysteresis loops prepared by nanoparticle spin coating.  

PubMed

This communication describes the synthesis of spin-crossover nanoparticles, which can disperse in various organic solvents without an excess amount of surfactants. The nanoparticles form homogeneous thin films on substrates by spin coating. The films show abrupt spin transitions with large thermal hysteresis loops. PMID:25045761

Tanaka, Daisuke; Aketa, Naoki; Tanaka, Hirofumi; Tamaki, Takashi; Inose, Tomoko; Akai, Tomoki; Toyama, Hirotaka; Sakata, Osami; Tajiri, Hiroo; Ogawa, Takuji

2014-09-11

231

Interactive aesthetic curve segments  

Microsoft Academic Search

To meet highly aesthetic requirements in in- dustrial design and styling, we propose a new category of aesthetic curve segments. To achieve these aesthetic requirements, we use curves whose logarithmic curvature histograms(LCH) are represented by straight lines. We call such curves aesthetic curves. We identify the overall shapes of aesthetic curves depending on the slope of LCH ?, by imposing

Norimasa Yoshida; Takafumi Saito

2006-01-01

232

Overcoming Inhomogeneity and Hysteresis Limitations of Type R Thermocouples in an International Comparison  

NASA Astrophysics Data System (ADS)

Type R thermocouples are widely used and convenient high-temperature transfer standards; however, the achievable accuracy is limited by the effects of inhomogeneity and hysteresis. In this article, we summarize the results of the recent international comparison APMP-T-S1-04 and discuss the results of the thermoelectric scanning, spatially resolved over the length of the thermocouples. The thermoelectric signatures show both reversible (hysteresis) and irreversible inhomogeneities introduced by the calibration processes used by the participants. The results demonstrate that although the reversible hysteresis of Type R thermocouples limits their performance as a transfer standard in thermometry, this can be managed by appropriate design of the comparison protocol. By performing all calibrations from lower to higher temperatures from an initial 450°C anneal state, a pilot laboratory reproducibility of typically 0.03°C ( k = 2) and a reference value uncertainty of 0.03 0.06°C (at k = 2) over 0 1,100°C were achieved. This allowed statistically significant testing of the calibration capabilities of all the participants.

Jahan, Ferdouse; Ballico, Mark

2007-12-01

233

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

NASA Technical Reports Server (NTRS)

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.

Bachmann, Kurt T.; White, Oran R.

1994-01-01

234

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

USGS Publications Warehouse

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.

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

2014-01-01

235

A survey on hysteresis modeling, identification and control  

NASA Astrophysics Data System (ADS)

The various mathematical models for hysteresis such as Preisach, Krasnosel'skii-Pokrovskii (KP), Prandtl-Ishlinskii (PI), Maxwell-Slip, Bouc-Wen and Duhem are surveyed in terms of their applications in modeling, control and identification of dynamical systems. In the first step, the classical formalisms of the models are presented to the reader, and more broadly, the utilization of the classical models is considered for development of more comprehensive models and appropriate controllers for corresponding systems. In addition, the authors attempt to encourage the reader to follow the existing mathematical models of hysteresis to resolve the open problems.

Hassani, Vahid; Tjahjowidodo, Tegoeh; Do, Thanh Nho

2014-12-01

236

Hysteresis in Granular Media Subjected to Axisymmetrical Rotation  

NASA Astrophysics Data System (ADS)

In this work we have studied the hysteretic behavior for the mean slope of the free surface of noncohesive granular media under axisymmetricalrotation. In order to study the hysteresis loop the relationship between theaverage slope of the free surface (most important measurable quantity) andthe Froude number has been established. Differences between experiments andtheoretical predictions are also shown. Theory predicts that hysteresis mustdisappear as the friction coefficient µ of the granular materialreaches unity. However, this condition could not be reached experimentallyusing tapioca (where µ˜1), due to the important difference betweenthe angle of internal friction and the angle of repose for small containers.

Medina, Abraham; Treviño, Casay

1999-06-01

237

A compensation method for the hysteresis error of DVD VCM  

NASA Astrophysics Data System (ADS)

The present study considers an autofocusing laser probe system used for the measurement of the surface profile and roughness of an object. The system is based upon a modified pickup head of a commercially available DVD player which uses a voice coil motor (VCM) to drive an objective lens during the autofocusing process. It is known that hysteresis of the VCM during the autofocusing process reduces the precision of the measurement results. Consequently, the present investigation adopts a hysteresis model to develop a compensation method which can improve the accuracy of the optical pickup head within the measurement system.

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

2004-04-01

238

Wave interaction in acoustic resonators with and without hysteresis.  

PubMed

Nonlinear interaction of counterpropagating waves in solids is considered by using a general approach taking into account only the cumulative (resonant) nonlinear perturbations giving a nonzero contribution over the period and, consecutively, potentially able to significantly modify the linear solution. Different stress-strain relations are addressed, including those with hysteresis which serve as basic models for the recent acoustic experiments with rock and metals. An important case of the interaction of counterpropagating waves with close amplitudes in a high-Q resonator (bar) with hysteresis is specially addressed and compared with the case of a ring resonator. PMID:15658687

Ostrovsky, Lev A

2004-12-01

239

Large-scale separation and hysteresis in cascades  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

240

Modeling of Switching and Hysteresis in Molecular Transport  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

241

Memory characteristics of hysteresis and creep in multi-layer piezoelectric actuators: An experimental analysis  

NASA Astrophysics Data System (ADS)

In this paper we provide an experimental characterization of creep and hysteresis in a multi-layer piezoelectric actuator (PEA), taking into account their relationships in terms of memory structure. We fit the well-known log-t model to the response of the PEA when driven by piecewise-constant signals, and find that both the instantaneous and the delayed response of the PEA display hysteretic dependence on the voltage level. We investigate experimentally the dependence of the creep coefficient on the input history, by driving the PEA along first-order reversal curves and congruent minor loops, and find that it displays peculiar features like strict congruence of the minor loops and discontinuities. We finally explain the observed experimental behaviors in terms of a slow relaxation of the staircase interface line in the Preisach plane.

Biggio, Matteo; Butcher, Mark; Giustiniani, Alessandro; Masi, Alessandro; Storace, Marco

2014-02-01

242

Curves of constant width  

Microsoft Academic Search

Curves of constant width have the same breadth regardless of how they are rotated. Highly noncircular curves with this property may be constructed geometrically. Such curves make good rollers, manhole covers, and allow one to drill nearly square holes.

James A. Flaten

1999-01-01

243

Curves of constant width  

NASA Astrophysics Data System (ADS)

Curves of constant width have the same breadth regardless of how they are rotated. Highly noncircular curves with this property may be constructed geometrically. Such curves make good rollers, manhole covers, and allow one to drill nearly square holes.

Flaten, James A.

1999-10-01

244

A modeling approach to represent hysteresis in capillary pressure-saturation relationship based on fluid connectivity in void space  

NASA Astrophysics Data System (ADS)

This study presents a new model for description of hysteretic constitutive relationships between capillary pressure and saturation under capillary-dominated multiphase flow conditions in porous media. Hysteretic relationships are required for accurate prediction of spatial and temporal distribution of multiphase fluids in response to successively occurring drainage and imbibition events in porous media. In addition to contact angle effects, connectivity of the void space in the porous medium plays a central role for the macroscopic manifestation of hysteresis behavior and capillary entrapment of wetting and nonwetting fluids. The hysteretic constitutive model developed in this work uses void-size distribution and a measure of connectivity for void space to compute the hysteretic curves and to predict entrapped fluid-phase saturations. Two functions, the drainage connectivity function and the wetting connectivity function, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model results are verified by comparing the model predicted scanning curves with 3-D pore-scale simulations as well as with actual data sets obtained from column experiments found in the literature.

Cihan, Abdullah; Birkholzer, Jens; Illangasekare, Tissa H.; Zhou, Quanlin

2014-01-01

245

A Theoretical Approach Representing Hysteresis in Capillary Pressure-Saturation Relationship Based on Connectivity in Void Space  

NASA Astrophysics Data System (ADS)

This study presents a new theoretical model for description of hysteretic constitutive relationships between capillary pressure and saturation under capillary-dominated multiphase flow conditions in porous media. Hysteretic relationships are required for the accurate prediction of the spatial and temporal distribution of multiphase fluids in response to successively occurring drainage and imbibition events in porous media. In addition to contact angle effects, the connectivity of the void space in the porous medium plays a central role for the macroscopic manifestation of hysteresis behavior and capillary entrapment of wetting and non-wetting fluids. The hysteretic constitutive model developed in this work uses void-size distribution and a measure of connectivity of void space to compute the hysteretic curves and to predict entrapped fluid phase saturations. Two functions, the probability of drainage and the probability of wetting, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model results are verified by comparing the model predicted scanning curves with 3D pore-scale simulations as well as with actual data sets obtained from column experiments found in the literature.

Cihan, A.; Birkholzer, J. T.; Illangasekare, T. H.; Zhou, Q.

2013-12-01

246

Influence Factors on Critical Speed Hysteresis in Railway Vehicles  

Microsoft Academic Search

This research has been performed to estimate the hunting motion hysteresis of railway passenger cars. An old and a new car with almost the same structure are chosen for analysis models. To solve a set of simultaneous equations of motion that are strongly coupled with creep relations effectively, a shooting algorithm in which the nonlinear relations are regarded as a

Woo-Jin Chung; Jae-Kyung Shim

2003-01-01

247

A compensation method for the hysteresis error of DVD VCM  

Microsoft Academic Search

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

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

2004-01-01

248

PID Control of Second-Order Systems with Hysteresis  

E-print Network

Ryan Department of Mathematical Sciences University of Bath Bath BA2 7AY, UK May 2007 Revised: October]. By contrast, in this paper we deal with a large class of rate-independent causal hysteresis operators which/01 Corresponding author, e-mail: hl@maths.bath.ac.uk 2 #12;in [12, 13] which ensure existence, regularity

Ryan, E.P.

249

The back transition and hysteresis effects in DIII-D  

SciTech Connect

The back transition from H-mode to L-mode has been studied on DIII-D as a part of the investigation of the L-H transition power threshold scaling. Based on a density-dependent scaling for the H-mode power threshold, ITER will require substantial hysteresis in this parameter to remain in H-mode as n{sub e} rises. Defining the hysteresis in terms of the ratio of sustaining to threshold power, P{sub HL}/P{sub LH} may need to be as small as 50% for ITER. Operation of DIII-D at injection powers slightly above the H-mode threshold results in an oscillatory behavior with multiple forward-backward transitions in the course of a discharge. These discharges represent a unique system for studying various control parameters that may influence the H{leftrightarrow}L state transition. Careful analysis of the power flow through the edge gives values for the sustaining power which are well below the corresponding threshold powers (P{sub HL}/P{sub LH} = 35--70%), indicating substantial hysteresis can be achieved in this parameter. Studies of other control parameter candidates such as edge temperature during the back transitions are less clear: the amount of hysteresis seen in these parameters, if any, is primarily dependent on the nature (ELMing, ELM-free) of the parent H-state.

Thomas, D.M.; Groebner, R.J.; Burrell, K.H.; Osborne, T.H.; Carlstrom, T.N. [General Atomics, San Diego, CA (United States)

1997-09-01

250

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 design. i #12; 1 Introduction Piezoelectric materials provide the capability for designing actuators piezoelectric effects. As a result of the ferroelectric nature of the materials, they also exhibit varying

251

Nonlinear Reptation in Molecular Based Hysteresis Models for Polymers  

E-print Network

direction involves exploration of multiscale aspects of polymeric structural modeling with uncertaintyNonlinear Reptation in Molecular Based Hysteresis Models for Polymers H.T. Banks and Negash G. Medhin Center for Research in Scientific Computation North Carolina State University Raleigh, NC 27695

252

Parameter Estimation Techniques for a Polarization Hysteresis Model  

E-print Network

formulations [1, 2, 12, 19], and (iii) domain wall models [6, 8, 11, 14, 15]. The first two are formulated as integral equations whereas the domain wall models are typically posed as differential equations techniques for models quantifying hysteresis and constitutive nonlinearities in ferroelectric materials

253

Parameter Estimation Techniques for a Class of Nonlinear Hysteresis Models  

E-print Network

energy models [8,10,18­20,24,25], Preisach formulations [2,3,5,7,16,26], and domain wall models [6,8,14,21,22]. As detailed in [17], the domain wall framework is efficient to implement but requires a priori knowledge hysteresis and constitutive nonlinearities inherent to ferroelectric, ferromagnetic and ferroelastic

254

Test Analysis and Calculation of Polyphase Hysteresis Motors  

Microsoft Academic Search

This paper presents a method of analyzing hysteresis motors for their parameters, gross power, losses and magnetizing ampere turns. A method is shown for calculating performance from either calculated or tested parameters. A synthesis method is given for determining rotor ring thickness.

P. H. Trickey

1972-01-01

255

Modeling and optimum design of disk-type hysteresis motors  

Microsoft Academic Search

In this paper, calculation of electrical equivalent circuit parameters versus design parameters of high frequency disk-type hysteresis motors are presented in details for steady state operating conditions. It is demonstrated that some of the equivalent circuit parameters alter significantly with input voltage and for different operating conditions. Therefore an equivalent circuit with fixed elements may give an inaccurate prediction of

Ahmad Darabi; Hamid Lesani; Teimoor Ghanbari; A. Akhavanhejazi

2007-01-01

256

An Analysis of the Hysteresis Motor Part III: Parasitic Losses  

Microsoft Academic Search

A major constraint on the performance prediction of a hysteresis machine arises from the parasitic losses associated with the rotor magnetic material. These losses can be high enough to absorb much of the developed torque, particularly for small sizes and large numbers of poles. In this paper the phenomena which cause parasitic losses are examined in detail. Analytical expressions are

M. A. Rahman; Miles Copeland; Gordon Slemon

1969-01-01

257

ASYNCHRONOUS PERFORMANCE OF HYSTERESIS MOTOR CONSIDERING EDDY-CURRENT EFFECTS  

Microsoft Academic Search

A simplified model of the hysteresis motor is introduced, with eddy-current effects taken into consideration. The field analysis is based on Maxweell's equations; the output relations, such as forces, power and heat losses, are derived via Maxwell's stress tensor and Poynting's theorem, and a special variant of the circle diagram is proposed.

S. GAVRIL; A. MOR

1983-01-01

258

Design Optimization of Multistack Coreless Disk-Type Hysteresis Motor  

Microsoft Academic Search

Coreless dual disks hysteresis motors (CDDHM) have been recently introduced. The CDDHM presents some improve- ments in power factor and efficiency compared to general hystere- sis machines. However, there is not much design or manufacturing experience available and an initial design methodology has not yet been proposed for the new machine. According to this and existing inherent complexity in the

Ahmad Darabi; Mohammad Hossein Sadeghi; Amir Hassannia

2011-01-01

259

Computerized magnetic test and evaluation of hysteretic materials [hysteresis motors  

Microsoft Academic Search

Techniques are described which enable highly nonlinear hysteretic materials to be fully characterized. Major hysteresis loops and minor trajectories are presented for one particular material sample. Test time is reduced to less than 10s, ensuring that heating effects in the ring sample are negligible. The method is appropriate for detailed material investigation for design or development applications. It is recognized,

P. T. Jowett; D. I. MacInnes

1989-01-01

260

Hysteresis electrical motors with bulk melt-textured YBCO  

Microsoft Academic Search

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

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

261

Sensor Saturation for Hysteresis Reduction in GMR Magnetometers  

E-print Network

Sensor Saturation for Hysteresis Reduction in GMR Magnetometers Philip S. Mease and Robert R technologies for the development of general-purpose magnetometers. They are applicable for both AC and DC of a magnetic field and instruments that make this measurement are known as magnetometers. The most common

Krchnavek, Robert R.

262

A Differential Model of Adsorption Hysteresis with Applications to Chromatography  

E-print Network

A Differential Model of Adsorption Hysteresis with Applications to Chromatography M. Peszy- ena occuring in chromatography or other related disciplines, see [21]. These models have the general rise in the beginning of 20th century, chromatography has become a wide industrial domain delivering

Peszynska, Malgorzata

263

Accounting for slow drainage and hysteresis in irrigation scheduling  

Microsoft Academic Search

Soils continue to drain for several days following irrigation. Water budgeting predictions can be improved by accounting for this, provided hysteresis is recognized in the “field capacity” condition. Uncertainty in this condition was evident in experiments comparing predicted soil water depletions with neutron probe measurements. Comparisons were made for potato, lettuce and calabrese crops, irrigated by hose-reel machine. Best agreement

M. E. Parkes; D. B. Naysmith; M. A. McDowall

1989-01-01

264

Periodic solutions of a forced system with hysteresis.  

NASA Technical Reports Server (NTRS)

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

Drew, J. H.

1972-01-01

265

Elastic guides reduce hysteresis effect in Belleville spring package  

NASA Technical Reports Server (NTRS)

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

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

1967-01-01

266

Small hysteresis and high energy storage power of antiferroelectric ceramics  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

267

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

SciTech Connect

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

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

2010-10-15

268

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

USGS Publications Warehouse

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.

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

2013-01-01

269

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

NASA Astrophysics Data System (ADS)

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.

Qu, Minni; Li, Hui; Liu, Ran; Zhang, Shi-Li; Qiu, Zhi-Jun

2014-01-01

270

Hysteresis in the dynamic perception of scenes and objects.  

PubMed

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. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:25150947

Poltoratski, Sonia; Tong, Frank

2014-10-01

271

National Curve Bank  

NSDL National Science Digital Library

The National Curve Bank displays representations of two- and three-dimensional curves. Geometrical, algebraic, and historical aspects of curves are included. Educators and students have access to animations, interactions, java applets, Mathematica code, and more. Users may submit curves. Materials are reveiwed and selected by faculty at Cal State Los Angeles.

2009-03-01

272

Characterizations of Special Curves  

E-print Network

In this study, the new characterizations of special curves are investigated without using the curvatures of these special curves: general helices, slant helices, Bertrand curves, Mannheim curves. The curvatures are given by the help of the norms of the derivatives of Frenet vectors.

Yayli, Yusuf

2012-01-01

273

Darwin curves and galaxy arms  

NASA Astrophysics Data System (ADS)

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.

He, Jin

2014-07-01

274

Understanding curved detonation waves  

SciTech Connect

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

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

1992-10-01

275

Understanding curved detonation waves  

SciTech Connect

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

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

1992-01-01

276

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

Microsoft Academic Search

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

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

1998-01-01

277

Modeling and control with hysteresis and creep of ionic polymer-metal composite (IPMC) actuators  

Microsoft Academic Search

Hysteresis and creep hinder the effective use of IPMC in sensors and actuators. This paper proposes a hybrid model that can precisely portray hysteresis and creep in piezoelectric actuators, which is constructed by a Preisach operator with a piecewise uniform density function and creep operator. Then, the corresponding inverse models for both hysteresis and creep are developed. It studies online

Zhen Chen; Lina Hao; Dingyu Xue; Xinhe Xu; Yanmei Liu

2008-01-01

278

A Model for RateDependent Hysteresis in Piezoceramic Materials Operating at Low Frequencies  

E-print Network

A Model for Rate­Dependent Hysteresis in Piezoceramic Materials Operating at Low Frequencies Ralph contribute to hysteresis inherent to piezoelectric materials operating at low frequencies. While quasistatic the full capabilities of the materials. The model employed here quantifies the hysteresis in two steps

279

Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume.  

PubMed

The growth and reduction of Northern Hemisphere ice sheets over the past million years is dominated by an approximately 100,000-year periodicity and a sawtooth pattern (gradual growth and fast termination). Milankovitch theory proposes that summer insolation at high northern latitudes drives the glacial cycles, and statistical tests have demonstrated that the glacial cycles are indeed linked to eccentricity, obliquity and precession cycles. Yet insolation alone cannot explain the strong 100,000-year cycle, suggesting that internal climatic feedbacks may also be at work. Earlier conceptual models, for example, showed that glacial terminations are associated with the build-up of Northern Hemisphere 'excess ice', but the physical mechanisms underpinning the 100,000-year cycle remain unclear. Here we show, using comprehensive climate and ice-sheet models, that insolation and internal feedbacks between the climate, the ice sheets and the lithosphere-asthenosphere system explain the 100,000-year periodicity. The responses of equilibrium states of ice sheets to summer insolation show hysteresis, with the shape and position of the hysteresis loop playing a key part in determining the periodicities of glacial cycles. The hysteresis loop of the North American ice sheet is such that after inception of the ice sheet, its mass balance remains mostly positive through several precession cycles, whose amplitudes decrease towards an eccentricity minimum. The larger the ice sheet grows and extends towards lower latitudes, the smaller is the insolation required to make the mass balance negative. Therefore, once a large ice sheet is established, a moderate increase in insolation is sufficient to trigger a negative mass balance, leading to an almost complete retreat of the ice sheet within several thousand years. This fast retreat is governed mainly by rapid ablation due to the lowered surface elevation resulting from delayed isostatic rebound, which is the lithosphere-asthenosphere response. Carbon dioxide is involved, but is not determinative, in the evolution of the 100,000-year glacial cycles. PMID:23925242

Abe-Ouchi, Ayako; Saito, Fuyuki; Kawamura, Kenji; Raymo, Maureen E; Okuno, Jun'ichi; Takahashi, Kunio; Blatter, Heinz

2013-08-01

280

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

NASA Astrophysics Data System (ADS)

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.

Zheng, Jiashan; Wang, Yifu

2014-05-01

281

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

E-print Network

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 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.

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

2014-07-27

282

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

E-print Network

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 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.

Musterd, Michiel; Kleijn, Chris R; Kreutzer, Michiel T

2014-01-01

283

7 CFR 43.105 - Operating characteristics (OC) curves.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Operating characteristics (OC) curves. 43.105 Section 43.105 Agriculture... Sampling Plans § 43.105 Operating characteristics (OC) curves. The OC curves shows the ability of...

2010-01-01

284

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

NASA Astrophysics Data System (ADS)

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.

Landers, Mark N.; Sturm, Terry W.

2013-09-01

285

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

USGS Publications Warehouse

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.

Landers, Mark N.; Sturm, Terry W.

2013-01-01

286

Efficiency of Hysteresis Rods in Small Spacecraft Attitude Stabilization  

PubMed Central

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

Farrahi, Assal; Sanz-Andres, Angel

2013-01-01

287

Attachment/detachment hysteresis of fiber-based magnetic grabbers.  

PubMed

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

Gu, Yu; Kornev, Konstantin G

2014-04-28

288

Two liquids wetting and low hysteresis electrowetting on dielectric applications.  

PubMed

This study focuses on electrowetting using two immmiscible liquids on a dielectric coating. It is demonstrated that low contact angle of oil on the hydrophobic surfaces is a key parameter to obtain a low hysteresis system, below 2 degrees . On the basis of these results, three aspects of the wetting properties have been studied: the influence of the surface hydrophobic properties, the design of the liquids according to the hydrophobic surface, and a graphical method to solve the Bartell-Osterhof equation and predict the wetting properties of two liquids on a surface. These results define clear design rules to obtain a low hysteresis system, useful for many applications from liquid lenses to displays and laboratory-on-a-chip. PMID:19459706

Maillard, Mathieu; Legrand, Julien; Berge, Bruno

2009-06-01

289

Hysteresis in swelling and in sorption of wood tissue.  

PubMed

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

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

2013-06-01

290

Method of thermal strain hysteresis reduction in metal matrix composites  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

291

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

PubMed

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

Huang, Tao; Duman, John G

2002-03-01

292

Ignition, extinction, and thermal hysteresis of a heterogeneous exothermic reaction  

Microsoft Academic Search

Critical conditions of ignition and extinction are studied theoretically for the case of a heterogeneous exothermic reaction\\u000a proceeding on the uniformly accessible surface of a channel or a pore. Particular emphasis is placed on the thermal-hysteresis\\u000a effect of the reaction (an ignition temperature in excess of the extinction temperature), which ensures stability of the reaction\\u000a against changes in the external

I. G. Assovskii

1998-01-01

293

Applications of hysteresis switching in parameter adaptive control  

Microsoft Academic Search

The hysteresis switching algorithm of R.H. Middleton et al. (ibid., vol.33, no.1, p.50-8, Jan. 1988) is reexamined in a broader context. To demonstrate its utility, the algorithm is applied to various families of identifier-based parameterized controllers of both the direct and indirect control types. Application to the direct control type results in a model reference adaptive controller capable of stabilizing,

A. Stephen Morse; David Q. Mayne; Graham C. Goodwin

1992-01-01

294

Equivalent Circuits for Single-Phase Induction and Hysteresis Motors  

Microsoft Academic Search

General steady-state equivalent circuits are derived for the family of single-phase motors with unequal contrarotating magnetic fields produced by one or two stator windings and\\/or stator saliency, and rotor torque due to hysteresis and\\/or eddy- current action. The derivation of an equivalent quadrature motor, first shown by Kron, is extended to the range of motors under consideration. The idealized treatment

Denis O'Kelly

1971-01-01

295

TRANSIENT PERFORMANCE ANALYSIS OF POLYPHASE HYSTERESIS-RELUCTANCE MOTORS  

Microsoft Academic Search

This paper presents some important aspects of the run-up characteristics of polyphase hysteresis-reluctance motors. Analysis to predict the transient and asynchronous performances of these type of motors are presented. A general equivalent circuit model is developed for the sub-synchronous mode of operation. The experimental rotor was made of 36% cobalt-steel alloys and tested by using a stator of polyphase generalized

M. A. RAHMAN; A. M. OSHEIBA

1984-01-01

296

Transient Performance of Hysteresis Motors with Ferrite Magnets  

Microsoft Academic Search

This paper presents a general picture of basic features of the transient performance of circumferential-flux hysteresis motors when ferrite magnets (Ceramic–8) are oriented within the rotor. Based on the parallelogram approximation of the B-H loops of the magnetic materials, a mathematical model to predict the transient performance of such motors is given. This simple analysis is used in demonstrating various

A. M. Osheiba; M. A. Rahman

1986-01-01

297

Vector hysteresis measurements via a single disk tester  

NASA Astrophysics Data System (ADS)

In this paper we present a single disk tester (SDT) developed for vector hysteresis measurements of magnetic steels. The measurement system deals with a stator of a 3-phase induction motor and some suitable magnetic field and magnetic induction probes. Numerical calculations based to a FEM approach in time domain and experimental tests are shown in order to describe both accuracy and efficiency of this measurement system.

Cardelli, E.; Faba, A.

2006-02-01

298

Domain-wall motion in random potential and hysteresis modeling  

SciTech Connect

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.}

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

299

Novel thermal hysteresis proteins from low temperature basidiomycete, Coprinus psychromorbidus.  

PubMed

The low temperature basidiomycete, Coprinus psychromorbidus, produced three kinds of thermal hysteresis proteins (THPs) in the extracellular space. Molecular mass of purified fungal THPs were approximately 23 kDa, respectively, however those fungal THPs had different N-terminal amino acid sequences. Those fungal THPs formed ice crystals resembling "stone Age arrow head". These observations indicate that fungal THPs did not form hexagonal ice crystals to inhibit its growth. PMID:12908023

Hoshino, T; Kiriaki, M; Nakajima, T

2003-01-01

300

Magnetic hysteresis properties of melt-spun Nd-Fe-B alloys prepared by centrifugal method  

NASA Astrophysics Data System (ADS)

Magnetic hysteresis properties and microstructure peculiarities of melt spun Nd-Fe-B alloys (ribbons) prepared by melt quenching onto the internal surface of an iron spinning wheel at tangential speeds in the range 5-20 m/s are reported. The alloy composition was Nd-36% wt, B-1.2% wt. and Fe-remainder. It was found that the coercivity of ribbons does not practically depend on the wheel speed in applied range (18 kOe at 5 m/s and 22 kOe at 20 m/s), whereas the grain size of the basic phase (2-14-1) steadily decreases when the speed rises, starting from 2-3 ?m for 5 m/s alloy down to the 200-300 nm for 20 m/s alloy. All ribbons have normal convex demagnetization curves, even those prepared at low wheel speeds (without peculiar step near H˜0, which usually exists on such curves for traditionally prepared underquenched melt-spun Nd-Fe-B alloys). Grinding the ribbon in a vibration mill causes the coersivity drop to 7 kOe after 120 min of treatment. However, this operation increases the powder alignment ability and, as a result, the energy product for a fully dense magnet from anisotropic powder prepared from some ribbons rises to 20-23 MGOe.

Andreev, S. V.; Kudrevatykh, N. V.; Pushkarsky, V. I.; Markin, P. E.; Zaikov, N. K.; Tarasov, E. N.

1998-08-01

301

Influence of hysteresis on joint position sense in the human knee joint.  

PubMed

During muscle lengthening in a movement cycle the firing rate of muscle spindles is higher than during shortening. This phenomenon, known as hysteresis, has implications for movement control. Therefore, it should have an impact on joint position sense (JPS), the subject's awareness of the static position of a joint. JPS has been tested on the human knee joint by means of an angle reproduction test. This task included the following sequences. The leg was moved passively, by means of a motor drive, from two different start positions (15 degrees and 75 degrees) to a certain target angle and, after a time of 8 s, it was returned to the start position; subjects had to reproduce the former target angle. Several target angles, mild flexion (30 degrees), intermediate flexion (45 degrees), and strong flexion (60 degrees), were used. Depending on the start position, the movements matching these targets were flexions or extensions. At least for the intermediate position different threshold values should be expected for flexions and extensions, if hysteresis has an impact. Moreover, the JPS measure should show a dependence on movement velocity and independence on distance. Of the variables tested, only movement direction but not movement velocity or distance had a statistically significant impact on the dependent constant angle error (difference between reproduction and target angle). The target angle of 30 degrees was exactly reproduced (-0.14 degrees), independently of the start position. The 45 degrees target angle was significantly underestimated (-4.39 degrees) when matching that position by flexions (starting at 15 degrees) compared to an overestimation (2.27 degrees) when matching that position by extensions (starting at 75 degrees). The target angle of 60 degrees has been constantly underestimated (-3.80 degrees), independently of the start position. Therefore, hysteresis, the dependency of the movement's direction, neglected in the past, should be considered in future tests of JPS or studies considering the role of movement parameters for motor control. PMID:11131506

Weiler, H T; Awiszus, F

2000-11-01

302

Principal curves revisited  

Microsoft Academic Search

A principal curve (Hastie and Stuetzle, 1989) is a smooth curve passing through the ‘middle’ of a distribution or data cloud, and is a generalization of linear principal components. We give an alternative definition of a principal curve, based on a mixture model. Estimation is carried out through an EM algorithm. Some comparisons are made to the Hastie-Stuetzle definition.

Robert Tibshirani

1992-01-01

303

Measuring Extinction Curves of Lensing Galaxies  

E-print Network

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.

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

2005-01-22

304

Clapeyron slope reversal in the melting curve of AuGa2 at 5.5 GPa.  

PubMed

We use x-ray diffraction in a resistively heated diamond anvil cell to extend the melting curve of AuGa2 beyond its minimum at 5.5 GPa and 720 K, and to constrain the high-temperature phase boundaries between cubic (fluorite structure), orthorhombic (cottunite structure) and monoclinic phases. We document a large change in Clapeyron slope that coincides with the transitions from cubic to lower symmetry phases, showing that a structural transition is the direct cause of the change in slope. In addition, moderate (~30 K) to large (90 K) hysteresis is detected between melting and freezing, from which we infer that at high pressures, AuGa2 crystals can remain in a metastable state at more than 5% above the thermodynamic melting temperature. PMID:24025237

Geballe, Z M; Raju, S V; Godwal, B K; Jeanloz, R

2013-10-16

305

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

306

Ionically-mediated electromechanical hysteresis in transition metal oxides  

SciTech Connect

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.

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

2012-01-01

307

Mass Measurement System Using Relay Feedback with Hysteresis  

NASA Astrophysics Data System (ADS)

Mass measurement using a relay feedback system was studied experimentally. The measurement system has an on-off relay with hysteresis and switches force acting on the object in relation to its velocity. Such nonlinear control induces a limit cycle in the feedback system. The mass of the object is determined from the period of this limit cycle. The apparatus manufactured for experimental study uses two voice coil motors (VCM's), one of which is for driving the object and the other is for generating prescribed disturbances. The effects of system parameters and disturbances on measurement accuracy were examined experimentally.

Mizuno, Takeshi; Adachi, Takahiro; Takasaki, Masaya; Ishino, Yuji

308

Effect of contact angle hysteresis on moving liquid film integrity.  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

309

Effect of contact angle hysteresis on moving liquid film integrity  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

310

Local Condensation Curve from Dropwise to Glacial Region on Large Vertical Surface  

NASA Astrophysics Data System (ADS)

The existence of several regimes of condensation heat transfer is well known. Regimes are given academic names as dropwise, transition, film and glacial condensation along the condensation curve showing the relationship between heat flux and surface subcooling. In case of comparatively large vertical surface, the lower part on the gravitational direction is affected by condensate from the upper part, and will be covered by water stream like a rivulet. It has no longer an existence as dropwise condition, and it is absolutely impossible that heat transfer problems under constant temperature or constant heat flux take place. The reason is why as follows, heat transfer of film condensation is some orders of magnitude less than dropwise condensation, and various regimes exist together simultaneously. In the present paper we shall try to observe the coexisting appearance of regimes in steam condensation at atmospheric pressure and make researches in the local condensation curve from top to bottom on the same surface, that is divided into eight parts in the rear side. The main results are shown as follows (1) Enhancement of heat transfer by wiping of drops appears toward somewhat lower position from top. (2) Frazil ice is observed in the supercooled liquid film flowing down on glacial condensation. (3) The regime of glacial condensation describes a thermal hysteresis loop.

Haraguchi, Tadao; Shimada, Ryohachi; Takeyama, Toshiro

311

An Analysis of the Hysteresis Motor II-The Circumferential-Flux Machine  

Microsoft Academic Search

Part I of this paper presented an analysis of an idealized polyphase hysteresis machine having a radial-flux type of rotor. In this Part II, a hysteresis machine with a circumferential-flux type of rotor is analyzed. Using a rectangular loop approximation to the B-H characteristic of the hysteresis material, the flux density distribution in the machine is found and an equivalent

M. A. Copeland; G. R. Slemon

1964-01-01

312

Coreless Dual-rotor Disc Hysteresis Motor, Modeling, and Performance Prediction  

Microsoft Academic Search

Due to their robust structure, low and constant starting current, constant torque, and smooth and noiseless operation, small- and medium-sized power rating hysteresis motors are commonly employed in high-speed applications. However, hysteresis motors, in general, have a comparatively low power factor, efficiency, and torque density. In this article, a new structure, the coreless dual-rotor disc hysteresis motor, is introduced. Electromagnetic

Ahmad Darabi; Mohsen Sanati-Moghadam; Teymoor Ghanbari

2010-01-01

313

Modelling and analysis of a hysteresis motor used in space application  

Microsoft Academic Search

Summary form only given, as follows. We present the computer-aided modelling and analysis of a three-phase hysteresis synchronous motor used in the gyroscope as the gyro-rotor drive motor. A computer program is developed for the performance analysis of the hysteresis motor. The program accounts for all known losses in the hysteresis motor. The simulation program is tuned by incorporating the

K. R. Rajagopal; Christian Coltelli; Vasca Navale

2002-01-01

314

Experimental Investigation of the Pseudoelastic Hysteresis Damping Characteristics of Shape Memory Alloy Wires  

Microsoft Academic Search

An experimental investigation was conducted to determine the pseudoelastic hysteresis damping characteristics of Ni-Ti Shape Memory Alloy (SMA) wires. The comprehensive study examines the effects of cycling, oscillation frequency, strain amplitude, temperature, and static strain offset on the pseudoelastic stress-strain hysteresis of SMA wires under axial loading. Experimental data are obtained for complete austenite-martensite transformation hysteresis as well as partial

David Wolons; Farhan Gandhi; Brendon Malovrh

1998-01-01

315

Hysteresis zone or locus - Aerodynamic of bulbous based bodies at low speeds  

NASA Technical Reports Server (NTRS)

Experimental data are presented which seem to suggest that a well-defined hysteresis locus on bulbous based bodies at low speeds does not exist. Instead, if the experiment is repeated several times, the entire hysteresis region seems to fill with data rather than trace out a specific hysteresis locus. Data obtained on an oscillating model even at low reduced frequencies may be well defined but when applied to arbitrary motion lead to less accurate results than desired.

Covert, E. E.

1979-01-01

316

Water Repellency of Organic Growing Media and Its Consequences on Hysteretic Behaviours of the Water Retention Curve  

E-print Network

of the Water Retention Curve R. Naasz1, 2 , J.-C. Michel1 * and S. Charpentier1 * *Unit A462 1 Joint Research of this study was to estimate the influence of changes in wettability on the water retention properties of the two organic materials studied were observed. For peat, hysteresis was found in the water retention

Paris-Sud XI, Université de

317

The soil reference shrinkage curve  

E-print Network

A recently proposed model showed how a clay shrinkage curve is transformed to the soil shrinkage curve at the soil clay content higher than a critical one. The objective of the present work was to generalize this model to the soil clay content lower a critical one. I investigated (i) the reference shrinkage curve, that is, one without cracks; (ii) the superficial layer of aggregates, with changed pore structure compared with the intraaggregate matrix; and (iii) soils with sufficiently low clay content where there are large pores inside the intraaggregate clay (so-called lacunar pores). The methodology is based on detail accounting for different contributions to the soil volume and water content during shrinkage. The key point is the calculation of the lacunar pore volume variance at shrinkage. The reference shrinkage curve is determined by eight physical soil parameters: (1) oven-dried specific volume; (2) maximum swelling water content; (3) mean solid density; (4) soil clay content; (5) oven-dried structural porosity; (6) the ratio of aggregate solid mass to solid mass of intraaggregate matrix; (7) the lacunar factor that characterizes the rate of the lacunar pore volume change with water content; and (8) oven-dried lacunar pore volume. The model was validated using available data. The model predicted value of the slope of the reference shrinkage curve in the basic shrinkage area is equal to unity minus the lacunar factor value, and is between unity and zero in the agreement with observations.

V. Y. Chertkov

2014-03-11

318

Hysteresis of soft joints embedded with fluid-filled microchannels.  

PubMed

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

Ghatak, Animangsu; Majumder, Abhijit; Kumar, Rajendra

2009-02-01

319

Inelastic compaction, dilation and hysteresis of sandstones under hydrostatic conditions  

NASA Astrophysics Data System (ADS)

Sandstones display non-linear and inelastic behaviour such as hysteresis when subjected to cyclic loading. We present three hydrostatic compaction experiments with multiple loading-unloading cycles on Berea and Darley Dale sandstones and explain their hysteretic behaviour using non-linear inelastic compaction and dilation. Each experiment included eight to nine loading-unloading cycles with increasing maximum pressure in each subsequent cycle. Different pressure-volumetric strain relations during loading and unloading were observed. During the first cycles, under relatively low pressures, not all of the volumetric strain is recovered at the end of each cycle whereas at the last cycles, under relatively high pressures, the strain is recovered and the pressure-volumetric strain hysteresis loops are closed. The observed pressure-volumetric strain relations are non-linear and the effective bulk modulus of the sandstones changes between cycles. Observations are modelled with two inelastic deformation processes: irreversible compaction caused by changes in grain packing and recoverable compaction associated with grain contact adhesion, frictional sliding on grains or frictional sliding on cracks. The irreversible compaction is suggested to reflect rearrangement of grains into a more compact mode as the maximum pressure increases. Our model describes the `inelastic compaction envelope' in which sandstone sample will follow during hydrostatic loading. Irreversible compaction occurs when pressure is greater than a threshold value defined by the `inelastic compaction envelope'.

Shalev, Eyal; Lyakhovsky, Vladimir; Ougier-Simonin, Audrey; Hamiel, Yariv; Zhu, Wenlu

2014-05-01

320

Wavenumber selection and hysteresis in nonlinear baroclinic flow  

NASA Technical Reports Server (NTRS)

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.

Chou, Shih-Hung

1995-01-01

321

Curves, dynamical systems, and weighted point counting.  

PubMed

Suppose X is a (smooth projective irreducible algebraic) curve over a finite field k. Counting the number of points on X over all finite field extensions of k will not determine the curve uniquely. Actually, a famous theorem of Tate implies that two such curves over k have the same zeta function (i.e., the same number of points over all extensions of k) if and only if their corresponding Jacobians are isogenous. We remedy this situation by showing that if, instead of just the zeta function, all Dirichlet L-series of the two curves are equal via an isomorphism of their Dirichlet character groups, then the curves are isomorphic up to "Frobenius twists", i.e., up to automorphisms of the ground field. Because L-series count points on a curve in a "weighted" way, we see that weighted point counting determines a curve. In a sense, the result solves the analogue of the isospectrality problem for curves over finite fields (also know as the "arithmetic equivalence problem"): It states that a curve is determined by "spectral" data, namely, eigenvalues of the Frobenius operator of k acting on the cohomology groups of all ?-adic sheaves corresponding to Dirichlet characters. The method of proof is to show that this is equivalent to the respective class field theories of the curves being isomorphic as dynamical systems, in a sense that we make precise. PMID:23716684

Cornelissen, Gunther

2013-06-11

322

Parameter estimation of the Bouc Wen hysteresis model using particle swarm optimization  

NASA Astrophysics Data System (ADS)

Particle swarm optimization (PSO), which is a new robust stochastic evolutionary computational algorithm based on the movement and intelligence of swarms, is proposed to estimate parameters of the Bouc-Wen hysteresis model. The performance of the PSO method is compared with the more common genetic algorithms (GAs) in terms of parameter accuracy. Simulation results of the Bouc-Wen model with all the unknown parameters are illustrated to show that a higher quality solution with better computational efficiency than the GA method can be achieved by means of the PSO method. Furthermore, parameter estimation of the Bouc-Wen model with noisy data is considered. The results show that the proposed method is still effective even if the simulated data are corrupted by noise.

Ye, Meiying; Wang, Xiaodong

2007-12-01

323

The Curved Cube  

NSDL National Science Digital Library

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.

Hill, David R.

2003-02-24

324

Anodic Polarization Curves Revisited  

ERIC Educational Resources Information Center

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…

Liu, Yue; Drew, Michael G. B.; Liu, Ying; Liu, Lin

2013-01-01

325

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

PubMed

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

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

2006-05-28

326

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

327

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

NSDL National Science Digital Library

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.

Arup K. Chakraborty (Massachusetts Institute of Technology; Department of Chemical Engineering; REV); Jayajit Das (Massachusetts Institute of Technology; Department of Chemical Engineering; REV); Julie Zikherman (University of California; Department of Medicine; REV); Ming Yang (Massachusetts Institute of Technology; Department of Chemical Engineering; REV); Christopher C. Govern (Massachusetts Institute of Technology; Department of Chemical Engineering; REV); Mary Ho (University of California; Department of Anatomy; REV)

2009-04-14

328

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

SciTech Connect

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

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

1991-08-22

329

Interpretation of hysteresis behaviour of PI-PS multigraft copolymers by adapting to the dynamic flocculation model.  

SciTech Connect

Hysteresis behaviour of highly elastic multigraft copolymers with a polyisoprene (PI) backbone and branched polystyrene (PS) arms has been interpreted by applying the extended non-affine tube model of filler reinforced rubber elasticity (dynamic flocculation model), which takes into account that conformational fluctuations in bulk networks are strongly suppressed by packing effects. Originally, this model was developed to describe hyperelasticity of unfilled networks, and later, stress softening and hysteresis of filler reinforced elastomer materials like carbon black and silica filled rubbers. The evaluation of stress softening is obtained via pre-strain dependent hydrodynamic amplification of the rubber matrix by a fraction of rigid filler clusters with virgin filler filler bonds. The filler-induced hysteresis is described by a cyclic breakdown and re-aggregation of the residual fraction of more soft filler clusters with already broken filler filler bonds. We show, for the first time that the developed concept is in fair agreement with experimental stress strain data of superelastic PI PS multigraft copolymers. Depending on the PS-content and their functionality multigraft copolymers form microphase separated structures according to the constituting block copolymer concept, where the PS arms act as multi-domains in a PI matrix. The adaptation of the model is based on the assumption that the PS-domains are acting similar to filler clusters. The obtained microscopic material parameters appear reasonable for the description of the structure and mechanical properties of multigraft copolymers.

Staudinger, Ulrike [University of Jena, Institute of Materials Science and Technology, Jena Germany; Schlegel, Ralf [Fraunhofer IWM, Freiburg, German; Weidisch, Roland [Polymer Research Institute, Dresden Germany; Fritzsche, Juliane [Deutsches Institut fur Kautschuktechnologie e.V., Hannover, Germany; Kluppel, Manfred [Deutsches Institut fur Kautschuktechnologie e.V., Hannover, Germany; Heinrich, G. [Polymer Research Institute, Dresden Germany; Mays, Jimmy [ORNL; Uhrig, David [ORNL; Hadjichristidis, Nikos [University of Athens, Athens, Greece

2008-01-01

330

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

SciTech Connect

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.

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

331

Dissociative Recombination without a Curve Crossing  

NASA Technical Reports Server (NTRS)

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(+).

Guberman, Steven L.

1994-01-01

332

Relative permeability hysteresis and capillary trapping characteristics of supercritical CO2/brine systems: An experimental study at reservoir conditions  

NASA Astrophysics Data System (ADS)

We present the results of an experimental study on the effects of hysteresis on capillary trapping and relative permeability of CO2/brine systems at reservoir conditions. We performed thirty unsteady- and steady-state drainage and imbibition full-recirculation flow experiments in three different sandstone rock samples, low- and high-permeability Berea and Nugget sandstones. The experiments were carried out at various flow rates with both supercritical CO2 (scCO2)/brine and gaseous CO2 (gCO2)/brine fluid systems. The unsteady-state experiments were carried out with a wide range of flow rates to establish a broad range of initial brine saturations (Swi). This allowed investigation of the sensitivity of residual trapped CO2 saturation (S) to changes in Swi. The values were successfully compared with those available in the literature. For a given Swi, the trapped scCO2 saturation was less than that of gCO2 in the same sample. This was attributed to brine being less wetting in the presence of scCO2 than in the presence of gCO2. Post-imbibition dissolution of trapped CO2 and formation of dissolution front was also investigated. During the steady-state experiments, scCO2 and brine were co-injected with monotonically increasing or decreasing fractional flows to perform drainage and imbibition processes. We carried out seven sets of steady-state flow tests with various trajectories generating a comprehensive group of relative permeability hysteresis curves. The scanning curves revealed distinct features with potentially important implications for storage of scCO2 in geological formations. For both series of experiments, the ratio of S to initial CO2 saturation (1- Swi) was found to be much higher for low initial CO2 saturations. The results indicate that very promising fractions (about 49 to 83%) of the initial CO2 saturation can be stored through capillary trapping.

Akbarabadi, Morteza; Piri, Mohammad

2013-02-01

333

Measuring Model Rocket Engine Thrust Curves  

ERIC Educational Resources Information Center

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…

Penn, Kim; Slaton, William V.

2010-01-01

334

Cumulative growth of minor hysteresis loops in the Kolmogorov model  

SciTech Connect

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

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

2013-01-15

335

Inferring Pore Size and Network Structure from Sorption Hysteresis  

E-print Network

Sorption experiments are widely used to infer the pore size distribution of a mesoporous material. We present a simple model that explains the hysteresis observed on desorption in such experiments. The model is based on well-established relationships between the radius of a pore and the partial pressure at which it will fill, but additionally describes of the connectivity of the pore network. The model is able to explain both primary and scanning sorption isotherms for a range of materials with wide pore size distributions, such as cement paste and dental enamel. It allows quantification of the prevalence of macropores in the material, even though these pores are never filled during the sorption experiments. A distinct bump in the desorption isotherms is attributed to spinodal decomposition (or cavitation) at a partial pressure that depends on temperature, and experiments across a range of sorbents and sorbates are consistent with a universal scaling.

Matthew B. Pinson; Hamlin M. Jennings; Martin Z. Bazant

2014-02-14

336

Hysteresis and Contact forces in a Gas-fluidized Bed  

NASA Astrophysics Data System (ADS)

A gas-fluidized bed consists of an assembly of granular material fluidized by an upflow of gas. The "melting" of a static assembly of sand to the fluid state is hysteretic and proceeds through an intermediate state known as the "uniform fluid" which we have recently shown(Menon, N.; Durian, D.J. Particle motions in a gas-fluidized bed of sand. Phys. Rev. Lett., vol.79, 3407 (1997)) to be a weak, but motionless solid with enduring contacts between grains. We characterize the contact forces that stabilize this phase by measurements of the hysteresis in gas pressure vs gas velocity measurements and analyze them in terms of a yield stress for this soft solid. Since the chains of contact forces terminate at the boundaries of the bed, interesting boundary effects are anticipated. We probe finite-size effects in the magnitude of these forces obtained both by varying grain-size as well as aspect ratio of the bed.

Menon, Narayanan; Durian, Douglas

1998-03-01

337

The thermodynamic origin of hysteresis in insertion batteries  

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

338

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

PubMed

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

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

2014-01-01

339

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

PubMed

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

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

2014-01-24

340

Hysteresis and bistability in a realistic model for IP3-driven Ca2+ oscillations  

NASA Astrophysics Data System (ADS)

We present a new model for inositol triphosphate (IP3)-induced cytosolic Ca2+ oscillations in non-excitable cells. The model includes the various Ca2+ in- and efflux pathways reported to exist in these cells. In particular, it features the complex regulation of the Ca2+ release from the endoplasmic reticulum (ER) by IP3, cytosolic Ca2+ and Ca2+ in the ER. Bifurcation analysis revealed that the model accurately predicts the cytosolic Ca2+ dynamics in a typical non-excitable cell. Diffusional coupling of this model in a two-dimensional network shows hysteresis and bistability in its collective dynamics. Depending on the strength of the diffusion constant, we find traveling or spiral waves as solutions of this system.

Torres, J. J.; Willems, P. H. G. M.; Kappen, H. J.; Koopman, W. J. H.

2001-09-01

341

Hysteresis multicycles in nanomagnet arrays J. M. Deutsch, Trieu Mai, and Onuttom Narayan  

E-print Network

. INTRODUCTION Hysteresis in magnets 1,2 is a paradigm for all history dependent behavior in nature 3­5 . In addition, hysteresis is the cornerstone of the magnetic data storage industry, and of great technological- graph was measured. Whether a multicycle is present, and if so, its order, depended on the realization

California at Santa Cruz, University of

342

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

E-print Network

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

Libbrecht, Kenneth G.

343

Adaptive hysteresis band current control for transformerless single-phase PV inverters  

Microsoft Academic Search

Current control based on hysteresis algorithms are widely used in different applications, such as motion control, active filtering or active\\/reactive power delivery control in distributed generation systems. The hysteresis current control provides to the system a fast and robust dynamic response, and requires a simple implementation in standard digital signal platforms. On the other hand, the main drawback of classical

Gerardo Vázquez; Pedro Rodriguez; Rafael Ordoñez; Tamás Kerekes; Remus Teodorescu

2009-01-01

344

Physiological thermoregulation in a crustacean? Heart rate hysteresis in the freshwater crayfish Cherax destructor  

Microsoft Academic Search

Differential heart rates during heating and cooling (heart rate hysteresis) are an important thermoregulatory mechanism in ectothermic reptiles. We speculate that heart rate hysteresis has evolved alongside vascularisation, and to determine whether this phenomenon occurs in a lineage with vascularised circulatory systems that is phylogenetically distant from reptiles, we measured the response of heart rate to convective heat transfer in

Jacqueline E. Goudkamp; Frank Seebacher; Mark Ahern; Craig E. Franklin

2004-01-01

345

Isochronal annealing studies of a plastically deformed ferromagnetic metal using magnetic hysteresis measurements  

Microsoft Academic Search

An experimental study has been made of magnetic hysteresis in plastically deformed and annealed gadolinium (Gd) metal as a function of annealing temperature. Seven plastically deformed samples were annealed at temperatures ranging from 155° to 916°C; major and minor magnetic hysteresis loops of these seven samples plus one as-deformed sample were examined. The results are discussed in terms of the

Frederick Milstein; John A. Baldwin; Timothy W. James

1973-01-01

346

Temperature hysteresis of the domain structure of single-axis ferrimagnets  

Microsoft Academic Search

The temperature hysteresis of the domain structure of thin layers of single-axis ferrimagnets has been studied theoretically and experimentally varying the temperature. The relationships have been found for the qualitative description of the magnitude of the temperature hysteresis of the period of a band domain structure. The results of the calculation are in satisfactory agreement with experimental data obtained on

V. E. Ivanov; G. S. Kandaurova; E. F. Ledovskaya

1988-01-01

347

EXISTENCE OF FINITELY MANY SOLUTION BRANCHES AND NESTED HYSTERESIS LOOPS IN FERROELECTRIC MATERIALS  

E-print Network

. This results in nucleations and domain walls, and a relation between polarization and applied field, iEXISTENCE OF FINITELY MANY SOLUTION BRANCHES AND NESTED HYSTERESIS LOOPS IN FERROELECTRIC MATERIALS and Nested Hysteresis Loops in Ferroelectric Materials Jinhae Park Department of Mathematics Purdue

348

Analysis and microprocessor implementation of field oriented control for permanent magnet hysteresis synchronous motor  

Microsoft Academic Search

An analytical motor for a permanent magnet hysteresis hybrid synchronous motor has been developed. A microprocessor-based field oriented control scheme has been successfully experimented for a laboratory magnet hysteresis motor. A scheme for measuring the torque angle is proposed. The test results confirm the improvement of the dynamic performances using a field-oriented control strategy

J. Qian; M. Azizur Rahman

1991-01-01

349

Numerical and experimental comparison of electromechanical properties and efficiency of HTS and ferromagnetic hysteresis motors  

Microsoft Academic Search

Hysteresis motors are very attractive in a wide range of fractional power applications, due to its torque-speed characteristics and simplicity of construction. This motor's performance is expected to improve when HTS rotors are used, and in fact, hysteresis motors have shown to be probably the most viable electrical machines using HTS materials. While these motors, either conventional or HTS, are

D Inácio; S Inácio; J Pina; A Gonçalves; M Ventim Neves; A Leão Rodrigues

2008-01-01

350

Reinforcement Learning for Characterization of Hysteresis Behavior in Shape Memory Alloys, and Application to  

E-print Network

Reinforcement Learning for Characterization of Hysteresis Behavior in Shape Memory Alloys � Electric propulsion, advanced fuel cells, high- efficiency electric motors � Integrated advanced control�Strain Relationship: HYSTERESIS Behavior based on a 2-D FIELD, not a 2-D PATH #12;Kirkpatrick & Valasek - 6 CURRENT

Valasek, John

351

Cochlear hysteresis: Observation with low-frequency modulated distortion product otoacoustic emissions  

E-print Network

Cochlear hysteresis: Observation with low-frequency modulated distortion product otoacousticTr revealed a sigmoid-shaped hysteresis loop with counterclockwise traversal. Physiologic indices by the voltage- dependent conformational change of motor proteins, e.g., prestin Liberman et al., 2002 , residing

Allen, Jont

352

Analysis of a Hysteresis Motor on Asynchronous Speed Using Complex Permeability  

Microsoft Academic Search

This paper deals with a method for determining the complex permeability in analysis of hysteresis motors. The method assumes that the magnetic intensity distribution is sinusoidal in the direction of rotation. Analysis of the asynchronous speed of a hysteresis motor is then performed for cylindrical coordinates, using modified Bessel functions. The results of calculations are in good agreement with experimental

T. Horii; N. Yuge; G. Wakui

1994-01-01

353

Decentralized adaptive stabilization in the presence of unknown backlash-like hysteresis  

Microsoft Academic Search

Due to the difficulty of handling both hysteresis and interactions between subsystems, there is still no result available on decentralized stabilization of unknown interconnected systems with hysteresis, even though the problem is practical and important. In this paper, we provide solutions to this challenging problem by proposing two new schemes to design decentralized output feedback adaptive controllers using backstepping approach.

Changyun Wen; Jing Zhou

2007-01-01

354

Segmented shape memory alloy actuators using hysteresis loop control  

NASA Astrophysics Data System (ADS)

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

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

2006-04-01

355

The Art Show  

ERIC Educational Resources Information Center

This article describes what once was thought to be impossible--a formal art show extravaganza at an elementary school with 1,000 students, a Department of Defense Dependent School (DODDS) located overseas, on RAF Lakenheath, England. The dream of this this event involved the transformation of the school cafeteria into an elegant art show

Scolarici, Alicia

2004-01-01

356

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

PubMed Central

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

Othman, Sarbaz; Thomson, Robert; Lanner, Gunnar

2010-01-01

357

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

PubMed

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

Othman, Sarbaz; Thomson, Robert; Lannér, Gunnar

2010-01-01

358

The soil reference shrinkage curve  

E-print Network

A recently proposed model showed how a clay shrinkage curve is transformed to the soil shrinkage curve at the soil clay content higher than a critical one. The objective of the present work was to generalize this model to the soil clay content lower a critical one. I investigated (i) the reference shrinkage curve, that is, one without cracks; (ii) the superficial layer of aggregates, with changed pore structure compared with the intraaggregate matrix; and (iii) soils with sufficiently low clay content where there are large pores inside the intraaggregate clay (so-called lacunar pores). The methodology is based on detail accounting for different contributions to the soil volume and water content during shrinkage. The key point is the calculation of the lacunar pore volume variance at shrinkage. The reference shrinkage curve is determined by eight physical soil parameters: (1) oven-dried specific volume; (2) maximum swelling water content; (3) mean solid density; (4) soil clay content; (5) oven-dried structural...

Chertkov, V Y

2014-01-01

359

Breakpoint chlorination curves of greywater.  

PubMed

A study on chlorination of raw greywater with hypochlorite is reported in this paper. Samples were chlorinated in a variety of conditions, and residual chlorine (Cl2) was measured spectrophotometrically. For each sample, the chlorination curve (chlorine residuals versus chlorine dose) was obtained. Curves showed the typical hump-and-dip profile attributable to the formation and destruction of chloramines. It was observed that, after reactions with strong reductants and chloramines-forming compounds, the remaining organic matter exerted a certain demand of chlorine. The evolution of chlorination curves with addition of ammonia and dodecylbencene sulfonate sodium salt and with dilution of the greywater sample were studied. In addition, chlorination curves at several contact times have been obtained, resulting in slower chlorine decay in the hump zone than in the dip zone. In addition, the decay of coliforms in chlorinated samples was also investigated. It was found that, for a chlorination dosage corresponding to the maximum of the hump zone (average 8.9 mg Cl2/ L), samples were negative in coliforms after 10 to 30 minutes of contact time. After-growth was not observed within 3 days after chlorination. Implications in chlorination treatments of raw greywater can be derived from these results. PMID:17824528

March, J G; Gual, M

2007-08-01

360

Factors affecting drying and wetting soil-water characteristic curves of sandy soils  

Microsoft Academic Search

Drying and wetting soil-water characteristic curves (SWCCs) for five sandy soils are investigated using a Tempe pressure cell and capillary rise open tube. The test data are fitted to two SWCC equations using a least-squares algorithm. The obtained fitting parameters and some hysteretic behaviour are discussed and correlated with grain-size distribution parameters. A concept of total hysteresis is proposed to

Hong Yang; Harianto Rahardjo; Eng-Choon Leong; D. G. Fredlund

2004-01-01

361

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.

362

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

PubMed Central

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

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

2014-01-01

363

The Relevance and Implications of the Environmental Kuznets Curve Under Stock Effects and NonLinearities: A Hysteresis Based Approach  

Microsoft Academic Search

A number of studies in the past have come up in order to explain and verify the observation made by Grossman and Kruger that that there may exist an inverted U-shaped relationship between environmental pollution and income. While some studies have found this relationship to hold true for certain pollutants, other studies have rejected this hypothesis based upon empirical observations

Ram Ranjan; James S. Shortle; Elizabeth P. Marshall

2003-01-01

364

The Ozone Show.  

ERIC Educational Resources Information Center

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)

Mathieu, Aaron

2000-01-01

365

Showing What They Know  

ERIC Educational Resources Information Center

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…

Cech, Scott J.

2008-01-01

366

Chemistry Game Shows  

Microsoft Academic Search

We present a technological improvement to the use of game shows to help students review for tests. Our approach uses HTML files interpreted with a browser on a computer attached to an LCD projector. The HTML files can be easily modified for use of the game in a variety of courses.

Susan Campbell; Jennifer Muzyka

2002-01-01

367

Obesity in show cats.  

PubMed

Obesity is an important disease with a high prevalence in cats. Because obesity is related to several other diseases, it is important to identify the population at risk. Several risk factors for obesity have been described in the literature. A higher incidence of obesity in certain cat breeds has been suggested. The aim of this study was to determine whether obesity occurs more often in certain breeds. The second aim was to relate the increased prevalence of obesity in certain breeds to the official standards of that breed. To this end, 268 cats of 22 different breeds investigated by determining their body condition score (BCS) on a nine-point scale by inspection and palpation, at two different cat shows. Overall, 45.5% of the show cats had a BCS > 5, and 4.5% of the show cats had a BCS > 7. There were significant differences between breeds, which could be related to the breed standards. Most overweight and obese cats were in the neutered group. It warrants firm discussions with breeders and cat show judges to come to different interpretations of the standards in order to prevent overweight conditions in certain breeds from being the standard of beauty. Neutering predisposes for obesity and requires early nutritional intervention to prevent obese conditions. PMID:24612018

Corbee, R J

2014-12-01

368

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)

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.

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

2014-09-01

369

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

PubMed

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. PMID:25273736

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

2014-09-01

370

Show-Me Center  

NSDL National Science Digital Library

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

371

Show-Me Magazine  

NSDL National Science Digital Library

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.

2008-01-01

372

The Truman Show  

Microsoft Academic Search

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

Rolf F. Nohr

373

The Graphing Game Show  

NSDL National Science Digital Library

This lesson plan assesses student interpretation of graphs utilizing cooperative learning to further students understanding. Types of graphs used are horizontal and vertical bar graphs, picture graphs, and pictographs. In the lesson students play a game called the Graphing Game Show, in which they must work as a team to answer questions about specific graphs. The lesson includes four student resource worksheets and suggestions for extension and differentiation.

2011-01-01

374

A generalized Prandtl-Ishlinskii model for characterizing the hysteresis and saturation nonlinearities of smart actuators  

NASA Astrophysics Data System (ADS)

Smart actuators, such as shape memory alloy (SMA) and magnetostrictive actuators, exhibit saturation nonlinearity and hysteresis that may be symmetric or asymmetric. The Prandtl-Ishlinskii model employing classical play operators has been used to describe the hysteresis properties of smart actuators that are symmetric in nature. In this study, the application of a generalized play operator capable of characterizing symmetric as well as asymmetric hysteresis properties with output saturation is explored in formulating a generalized Prandtl-Ishlinskii model. The generalized play operator employs different envelope functions under increasing and decreasing inputs to describe asymmetric and saturated output-input hysteresis loops. The validity of the proposed generalized model to characterize symmetric and asymmetric hysteresis properties is demonstrated by comparing the model responses with the measured major and minor hysteresis loops of three different types of actuator, namely SMA, magnetostrictive, and piezoceramic actuators. The simulation results suggest that the proposed generalized Prandtl-Ishlinskii model can be directly applied for modeling the hysteresis loops of different smart actuators together with the output saturation.

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

2009-04-01

375

Exploring Area between Curves  

NSDL National Science Digital Library

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.

Monroy, Harumi

2006-01-01

376

Obesity in show dogs.  

PubMed

Obesity is an important disease with a growing incidence. Because obesity is related to several other diseases, and decreases life span, it is important to identify the population at risk. Several risk factors for obesity have been described in the literature. A higher incidence of obesity in certain breeds is often suggested. The aim of this study was to determine whether obesity occurs more often in certain breeds. The second aim was to relate the increased prevalence of obesity in certain breeds to the official standards of that breed. To this end, we investigated 1379 dogs of 128 different breeds by determining their body condition score (BCS). Overall, 18.6% of the show dogs had a BCS >5, and 1.1% of the show dogs had a BCS>7. There were significant differences between breeds, which could be correlated to the breed standards. It warrants firm discussions with breeders and judges in order to come to different interpretations of the standards to prevent overweight conditions from being the standard of beauty. PMID:22882163

Corbee, R J

2012-08-11

377

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

NASA Astrophysics Data System (ADS)

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

Lin, Yow-Jon; Lin, Yu-Cheng

2014-10-01

378

Implications of NiMH Hysteresis on HEV Battery Testing and Performance  

SciTech Connect

Nickel Metal-Hydride (NiMH) is an advanced high-power battery technology that is presently employed in Hybrid Electric Vehicles (HEVs) and is one of several technologies undergoing continuing research and development by FreedomCAR. Unlike some other HEV battery technologies, NiMH exhibits a strong hysteresis effect upon charge and discharge. This hysteresis has a profound impact on the ability to monitor state-of-charge and battery performance. Researchers at the Idaho National Engineering and Environmental Laboratory (INEEL) have been investigating the implications of NiMH hysteresis on HEV battery testing and performance. Experimental results, insights, and recommendations are presented.

Motloch, Chester George; Belt, Jeffrey R; Hunt, Gary Lynn; Ashton, Clair Kirkendall; Murphy, Timothy Collins; Miller, Ted J.; Coates, Calvin; Tataria, H. S.; Lucas, Glenn E.; Duong, T.Q.; Barnes, J.A.; Sutula, Raymond

2002-08-01

379

NPR: The Picture Show  

NSDL National Science Digital Library

National Public Radio's "The Picture Show" photo blog is a great way to avoid culling through the thousands of less interesting and engaging photographs on the web. With a dedicated team of professionals, this blog brings together different posts that profile various sets of photographs that cover 19th century war in Afghanistan, visual memories of WWII, unpublished photographs of JFK's presidential campaign, and abandoned buildings on the islands in Boston Harbor. Visitors can search through previous posts, use social media features to share the photo features with friends, and also sign up to receive new materials via their RSS feed. There's quite a nice mix of material here, and visitors can also comment on the photos and recommend the collection to friends and others.

380

Solar Light Show  

NSDL National Science Digital Library

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.

De Nie, Michael W.

381

Not a "reality" show.  

PubMed

The authors of the preceding articles raise legitimate questions about patient and staff rights and the unintended consequences of allowing ABC News to film inside teaching hospitals. We explain why we regard their fears as baseless and not supported by what we heard from individuals portrayed in the filming, our decade-long experience making medical documentaries, and the full un-aired context of the scenes shown in the broadcast. The authors don't and can't know what conversations we had, what documents we reviewed, and what protections we put in place in each televised scene. Finally, we hope to correct several misleading examples cited by the authors as well as their offhand mischaracterization of our program as a "reality" show. PMID:23631336

Wrong, Terence; Baumgart, Erica

2013-01-01

382

Avalanches and hysteresis in frustrated superconductors and XY spin glasses  

NASA Astrophysics Data System (ADS)

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.

Sharma, Auditya; Andreanov, Alexei; Müller, Markus

2014-10-01

383

Magnetoabsorption and magnetic hysteresis in Ni ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

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.

Hernández-Gómez, P.; Muñoz, J. M.; Valente, M. A.; Torres, C.; de Francisco, C.

2013-01-01

384

Graphing Polar Curves  

ERIC Educational Resources Information Center

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…

Lawes, Jonathan F.

2013-01-01

385

Atlas of fatigue curves  

Microsoft Academic Search

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

1986-01-01

386

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.

2012-07-11

387

Econophysics Master curve for  

E-print Network

-curve collapse of the price-impact function suggests that fluctuations from the supply- and-demand equilibrium this separately for buying and selling. The transactions are classified as being initiated by a buyer or seller is the liq- uidity and sign( ) is +1 or 1 for buying and selling, respectively. For all four years

388

Principal curve time warping  

Microsoft Academic Search

Time warping finds use in many fields of time series analysis, and it has been effectively implemented in many different application areas. Rather than focusing on a particular application area we approach the general problem definition, and employ principal curves, a powerful machine learning tool, to improve the noise robustness of existing time warping methods. The increasing noise level is

Umut Ozertem; Deniz Erdogmus

2009-01-01

389

Extinction curves in AGN  

E-print Network

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.

B. Czerny

2006-12-16

390

Extinction curves expected in young galaxies  

E-print Network

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.

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

2005-01-10

391

The Great Cometary Show  

NASA Astrophysics Data System (ADS)

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

2007-01-01

392

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

E-print Network

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

Laughlin, David E.

393

Investigation of the Temperature Hysteresis Phenomenon of a Loop Heat Pipe  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

394

Neck curve polynomials in neck rupture model  

SciTech Connect

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.

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

395

Numerical modeling of two-phase hysteresis combined with an interface condition for heterogeneous porous media  

Microsoft Academic Search

This paper presents a numerical implementation of two-phase capillary hysteresis and its combination with a capillary interface\\u000a condition for the treatment of heterogeneities. The hysteresis concepts chosen in this work are first implemented in a node-centered\\u000a FV discretization scheme and subsequently combined with the interface condition that predicts sharp saturation discontinuities\\u000a at material interfaces, based on a pressure equilibrium concept.

Alexandros Papafotiou; Hussam Sheta; Rainer Helmig

2010-01-01

396

Roughness dependent magnetic hysteresis of a few monolayer thick Fe films on Au(001)  

Microsoft Academic Search

We have studied quantitatively the surface and interface roughness of Fe films in a new monolayer regime on an Au(001) surface using the high-resolution low-energy electron diffraction technique. The hysteresis loops of those films were also measured in situ by the surface magneto-optical kerr effect technique. A correlation between the shape of hysteresis loops and the roughness of films was

Y.-L. He; G.-C. Wang

1994-01-01

397

Roughness dependent magnetic hysteresis of a few monolayer thick Fe films on Au(001)  

Microsoft Academic Search

We have studied quantitatively the surface and interface roughness of Fe films in a few monolayer regime on an Au(001) surface using the high-resolution low-energy electron diffraction technique. The hysteresis loops of those films were also measured insitu by the surface magneto-optical kerr effect technique. A correlation between the shape of hysteresis loops and the roughness of films was observed.

Y.-L. He; G.-C. Wang

1994-01-01

398

Studies on dielectric hysteresis of ferroelectric sodium vanadate, rubidium vanadate, cesium vanadate and their solid solutions  

Microsoft Academic Search

The dielectric hysteresis property of sodium vanadate, rubidium vanadate, cesium vanadate and their solid solutions has been\\u000a studied in the temperature range covering their transition points. The hysteresis loop method is used for coercive field measurements.\\u000a It was observed that the coercive field decreases with increasing temperature, and that it also decreases with increasing\\u000a sodium concentration in the solid solutions

V V Patil; A P Kashid; S H Chavan

1989-01-01

399

Ion-dosage-dependent room-temperature hysteresis in MOS structures with thin oxides  

Microsoft Academic Search

Two sets of metal-oxide-silicon (MOS) structures with oxide thicknesses of 115 and 350 Å, respectively, were exposed to 16-keV Si ion beams after dry oxidation. Small-signal capacitance-voltage measurements at room temperature revealed a hysteresis effect in the ion exposed samples, whose magnitude and direction depended on the ion dosage. No hysteresis could be detected in the control (unimplanted) samples. Mobile

Arya Raychaudhuri; S. Chatterjee; S. Ashok; S. Kar

1991-01-01

400

Neural modeling of rate-dependent and asymmetric hysteresis in ultrasonic motors  

Microsoft Academic Search

Usually, rotary travelling wave ultrasonic motor (RTWUSM) is involved with complex characteristic such as non-symmetric and rate-dependent hysteresis due to the inverse piezoelectric effect in the stator and the dynamics containing in the rotor. It is known that the hysteresis existing in RTWUSM is also a non-smooth nonlinearity with multi-valued mapping. Thus, the modeling of such characteristic of the RTWUSM

Xinliang Zhang; Yonghong Tan; Chun-Yi Su; Binyi Wu

2009-01-01

401

Fuzzy control design of a magnetically actuated optical image stabilizer with hysteresis compensation  

NASA Astrophysics Data System (ADS)

A fuzzy controller (FC) is designed for a magnetically actuated optical image stabilizer (OIS) in order to suppress the vibrations caused by hand shakings and hysteresis. To this end, the dynamic model of the OIS with consideration of hysteresis is first established, along with assuming the hand-shaking vibration as sinusoidal excitations. It is clearly shown that with capability of continuing parameter tuning, the FC is superior to the conventional PID for vibration suppression.

Tu, Tse-Yi; Chao, Paul C.-P.; Chiu, Chi-Wei; Wang, Chun-Chieh; Huang, Jeng-Shen

2009-04-01

402

An analytical solution for the field of a hysteresis motor based on complex permeability  

Microsoft Academic Search

A closed-form solution for the electromagnetic field distribution inside a hysteresis motor is presented. The solution is based upon Maxwell's field equations, considering the case of a circumferential-flux-type machine at synchronous speed. A hysteresis loop in the shape of an inclined ellipse is adopted. The application of the complex permeability concept to space rotating vectors is explained. A new form

Farouk A. A. Zaher

1990-01-01

403

Improved performance of polyphase hysteresis-reluctance motors fed from single-phase supplies  

Microsoft Academic Search

The balanced operation of a three-phase hysteresis-reluctance motor connected to a single-phase power supply was studied for both steady-state and dynamics modes of operation, and experimental tests were run to verify the analysis. Improved performance characteristics for balanced operation of a three-phase hysteresis-reluctance motor operated on a one-phase power supply are presented and optimum values of two-element balancers are shown

M. A. Rahman; A. M. Osheiba

1990-01-01

404

High-Efficiency operation of PWM inverter-driven hysteresis motor with short-duration overexcitation  

Microsoft Academic Search

This paper presents the new scheme for high-efficiency operation of PWM inverter-driven hysteresis motor with short-duration overexcitation. When the terminal voltage Vi of the hysteresis motor running at synchronous speed is continuously increased up to nVi (n>1) and then continuously decreased to Vi, input currents are reduced and output power is increased at the same time. Because of this, the

Tomotsugu Kubota; Takahiro Tamura; Kazumi Kurihara

2009-01-01

405

Analysis of field oriented control for permanent magnet hysteresis synchronous motors  

Microsoft Academic Search

A microprocessor implementation of the field-oriented control scheme for the permanent magnet (PM) hysteresis synchronous motor is reported. The basic principle is to decouple the torque-current component from the flux-current component so that these two components can be independently controlled. A d-q axis model of the PM hysteresis synchronous motor is presented, and the field-oriented control obtained from the basic

Jianhua Qian; M. Azizur Rahman

1993-01-01

406

Temperature response of soil respiration in a Chinese pine plantation: hysteresis and seasonal vs. diel Q10.  

PubMed

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

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

2013-01-01

407

Atlas of fatigue curves  

SciTech Connect

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.

Boyer, H.E.

1986-01-01

408

Curve parametrization by moments.  

PubMed

We present a method for deriving a parametric description of a conic section (quadratic curve) in an image from the moments of the image with respect to several specially-constructed kernel functions. In contrast to Hough-transform-type methods, the moment approach requires no large accumulator array. Judicious implementation allows the parameters to be determined using five multiplication operations and six addition operations per pixel. The use of moments renders the calculation robust in the presence of high-frequency noise or texture and resistant to small-scale irregularities in the edge. Our method is generalizable to more complex classes of curves with more parameters as well as to surfaces in higher dimensions. PMID:19029543

Popovici, Irina; Withers, William Douglas

2009-01-01

409

Curve-Skeleton Applications  

Microsoft Academic Search

Curve-skeletons are a 1D subset of the medial surface of a 3D object and are useful for many visualization tasks including virtual navigation, reduced-model formulation, visualization improvement, mesh repair, animation, etc. There are many algorithms in the literature describing extraction methodologies for different applications; however, it is unclear how general and robust they are. In this paper, we provide an

Nicu D. Cornea; Deborah Silver; Patrick Min

2005-01-01

410

Diffusion in Curved Spacetimes  

E-print Network

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.

Matteo Smerlak

2011-04-17

411

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

NASA Astrophysics Data System (ADS)

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.

Campbell, G. S.; Campbell, C. S.; Cobos, D. R.

2008-12-01

412

Curved microchannels and bacterial streamers  

NASA Astrophysics Data System (ADS)

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.

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

2010-03-01

413

The role of hysteresis in propagating acoustic wave in porous materials  

NASA Astrophysics Data System (ADS)

Hysteresis and end-point memory are universal behaviors of porous materials including rock, sandstone, soil, sediment, ceramic, and some cracked materials. Recently, there have been growing interests in studying hysteresis and linking this static property to dynamic behaviors, particularly in modeling nonlinear acoustic phenomena in porous materials. This study aims at exploring the role of hysteresis in propagation of an acoustic wave in soils. A modified triaxial cell was used to measure stress/strain and sound speed/strain relationships in a triaxial test. Soil samples were subjected to a load stress path that was designed to undergo a series of meso-scopic unload-reload stress cycles with axial strain in the range of 10Exp(-5)-10Exp(-4). It is found that the slope of the hysteresis loop is linearly correlated with the dynamic elastic modulus, which implies that the fluctuation of acoustic pressure may create micro-hysteresis loops that make the dynamic elastic modulus higher than static elastic modulus. This discovery may lead to a correction in the classical equation of state by adding a hysteresis term. [Work supported by the U.S. Department of Agriculture.

Lu, Zhiqu; Sabatier, James

2004-10-01

414

Rational curves and ruled orders on surfaces DANIEL CHAN 1  

E-print Network

Rational curves and ruled orders on surfaces DANIEL CHAN 1 , KENNETH CHAN University of New South projective surface Z ruled over a curve C say by f : Z - C. Let A be a maximal order of rank e2 on Z [ATV91], [A92]). Naturally, we would like to show that ruled orders have lots of rational curves

Chan, Daniel

415

Creases and Boundary Conditions for Subdivision Curves Jiri Kosinkaa  

E-print Network

control without introducing new control points. Keywords: Subdivision curve, B-spline, crease, boundary (including B´ezier end-conditions) in B-spline curves (and by extension in tensor- product B-spline surfaces), demonstrated on exam- ples of B-spline subdivision curves with creases. We show that relaxing some of our

Dodgson, Neil

416

Titania nanorods curve to lower their energy  

NASA Astrophysics Data System (ADS)

Spontaneous formation of curved nanorods is generally unexpected, since curvature introduces strain energy. However, electron microscopy shows that under hydrothermal conditions, some nanorods grown by oriented attachment of small anatase particles on {101} surfaces are curved and dislocation free. Molecular dynamics simulations show that the lattice energy of a curved anatase rod is actually lower than that of a linear rod due to more attractive long-range interatomic Coulombic interactions among atoms in the curved rod. The thermodynamic driving force stemming from lattice energy could be harnessed to produce asymmetric morphologies unexpected from classical Ostwald ripening with unusual shapes and properties.Spontaneous formation of curved nanorods is generally unexpected, since curvature introduces strain energy. However, electron microscopy shows that under hydrothermal conditions, some nanorods grown by oriented attachment of small anatase particles on {101} surfaces are curved and dislocation free. Molecular dynamics simulations show that the lattice energy of a curved anatase rod is actually lower than that of a linear rod due to more attractive long-range interatomic Coulombic interactions among atoms in the curved rod. The thermodynamic driving force stemming from lattice energy could be harnessed to produce asymmetric morphologies unexpected from classical Ostwald ripening with unusual shapes and properties. Electronic supplementary information (ESI) available: Synthesis of nanocrystalline titania; X-ray characterization of samples; electron microscopy (TEM and SEM) examination of samples; surface charges needed to bend an anatase nanorod; structure modeling and energy minimization; molecular dynamics (MD) simulations; structures of anatase nanorods from MD. See DOI: 10.1039/c3nr02616g

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

2013-07-01

417

Research and optimization on stator curve for roller pump  

NASA Astrophysics Data System (ADS)

By analyzing the advantages and disadvantages of common roller pump's stator curve (assuming that the roller on this stator curve has eliminated the void point), using curve fitting transitional method to pass the soft and hard impact point, then we can obtain a high order stator curve which has lower noise. By creating a smooth stator curve (and an inflection point with a common tangent) radial velocity mutation is eliminated. In order to avoid radial velocity mutation a symmetrical radial acceleration curve is used. In order to eliminate radial acceleration mutation, both ends of the radial acceleration change rate curve are valued zero. The results showed that due to the catastrophe point of the roller's stator curve, improving its stator curve eliminates the void point and the soft and hard impact point of the roller on the stator transitional curve. Compare the eighth-power stator curve with the improved stator curve, the improved curve also has the same superior performance. On the improved stator curve, the flow pulsation could be decreased by 241.39mL/min, with which the abrasion of the roller, the impact of the pump and the noise of the pump can be reduced.

Yang, G. L.; Zhang, J. F.; Su, H. S.; Zhang, L. Q.

2013-12-01

418

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

419

Rigid curves on $\\bar M_{0,n}$ and arithmetic breaks  

E-print Network

A result of Keel and McKernan states that a hypothetical counterexample to the F-conjecture must come from rigid curves on $\\bar {M}_{0,n}$ that intersect the interior. We exhibit several ways of constructing rigid curves. In all our examples, a reduction mod p argument shows that the classes of the rigid curves that we construct can be decomposed as sums of F-curves.

Castravet, Ana-Maria

2011-01-01

420

Large Thermal Hysteresis for Iron(II) Spin Crossover Complexes with N-(Pyrid-4-yl)isonicotinamide.  

PubMed

A new series of iron(II) 1D coordination polymers with the general formula [FeL1(pina)]·xsolvent with L1 being a tetradentate N2O2(2-) coordinating Schiff-base-like ligand [([3,3']-[1,2-phenylenebis(iminomethylidyne)]bis(2,4-pentanedionato)(2-)-N,N',O(2),O(2)'], and pina being a bridging axial ligand N-(pyrid-4-yl)isonicotinamide, are discussed. The X-ray crystal structure of [FeL1(pina)]·2MeOH was solved for the low-spin state. The compound crystallizes in the monoclinic space group P21/c, and the analysis of the crystal packing reveals the formation of a hydrogen bond network where additional methanol molecules are included. Different magnetic properties are observed for the seven samples analyzed, depending on the nature of the included solvent molecules. The widest hysteresis loop is observed for a fine crystalline sample of composition [FeL1(pina)]·xH2O/MeOH. The 88 K wide thermal hysteresis loop (T1/2? = 328 K and T1/2? = 240 K) is centered around room temperature and can be repeated without of a loss of the spin transition properties. For the single crystals of [FeL1(pina)]·2MeOH, a 51 K wide hysteresis loop is observed (T1/2? = 296 K and T1/2? = 245 K) that is also stable for several cycles. For a powder sample of [FeL1(pina)]·0.5H2O·0.5MeOH a cooperative spin transition with a 46 K wide hysteresis loop around room temperature is observed (T1/2? = 321 K and T1/2? = 275 K). This compound was further investigated using Mössbauer spectroscopy and DSC. Both methods reveal that, in the cooling mode, the spin transition is accompanied by a phase transition while in the heating mode a loss of the included methanol is observed that leads to a loss of the spin transition properties. These results show that the pina ligand was used successfully in a crystal-engineering-like approach to generate 1D coordination polymers and improve their spin crossover properties. PMID:25314334

Lochenie, Charles; Bauer, Wolfgang; Railliet, Antoine P; Schlamp, Stephan; Garcia, Yann; Weber, Birgit

2014-11-01

421

Generating artificial light curves: revisited and updated  

NASA Astrophysics Data System (ADS)

The production of artificial light curves with known statistical and variability properties is of great importance in astrophysics. Consolidating the confidence levels during cross-correlation studies, understanding the artefacts induced by sampling irregularities, establishing detection limits for future observatories are just some of the applications of simulated data sets. Currently, the widely used methodology of amplitude and phase randomization is able to produce artificial light curves which have a given underlying power spectral density (PSD) but which are strictly Gaussian distributed. This restriction is a significant limitation, since the majority of the light curves, e.g. active galactic nuclei, X-ray binaries, gamma-ray bursts, show strong deviations from Gaussianity exhibiting `burst-like' events in their light curves yielding long-tailed probability density functions (PDFs). In this study, we propose a simple method which is able to precisely reproduce light curves which match both the PSD and the PDF of either an observed light curve or a theoretical model. The PDF can be representative of either the parent distribution or the actual distribution of the observed data, depending on the study to be conducted for a given source. The final artificial light curves contain all of the statistical and variability properties of the observed source or theoretical model, i.e. the same PDF and PSD, respectively. Within the framework of Reproducible Research, the code and the illustrative example used in this paper are both made publicly available in the form of an interactive MATHEMATICA notebook.

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

2013-08-01

422

Heuristic Algorithm with Simulation Model for Searching Optimal Reservoir Rule Curves  

Microsoft Academic Search

This study proposes a heuristic algorithm to connect with simulation model for searching the optimal reservoir rule curves. The proposed model was applied to determine the optimal rule curves of the Ubolratana reservoir (the Chi River Basin, Thailand). The results showed that the pattern of the obtained rule curves similar to the existing rule curve. Then the obtained rule curves

Anongrit Kangrang; Sudarat Compliew; Witsanukorn Chaiyapoom

2009-01-01

423

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

NASA Astrophysics Data System (ADS)

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

Clark, Sarah; Ranganathan, Prabhakar; Friend, James

2009-11-01

424

Oscillatory model of crassulacean acid metabolism with a dynamic hysteresis switch  

PubMed Central

The mechanism of endogenous circadian photosynthesis oscillations of plants performing crassulacean acid metabolism (CAM) is investigated in terms of a nonlinear theoretical model. Unlike previous CAM models containing a discrete element, we use throughout continuous time differential equations which more adequately reflect the CAM dynamics. By incorporating results from a complementary and as well continuous membrane model, a detailed description of the molecular malate transport in and out of the vacuole through the tonoplast membrane is achieved. Our analysis shows that the membrane effectively acts as hysteresis switch regulating the oscillations. It thus provides a molecular basis for the circadian clock. The model shows regular endogenous limit cycle oscillations that are stable for a wide range of temperatures, in a manner that complies well with experimental data. The circadian period length is explained simply in terms of the filling time of the vacuole. The results emphasize the central role of membrane dynamics for the generation of circadian oscillations, and thus have general relevance for the explanation of biological clocks.

Blasius, B.; Neff, R.; Beck, F.; ttge, U. L

1999-01-01

425

Dielectric Hysteresis, Relaxation Dynamics, and Non-volatile Memory Effect in Carbon Nanotube Dispersed Liquid Crystal  

E-print Network

The self-organizing properties of nematic liquid crystals (LC) can be used to template carbon nanotubes (CNTs) on a macroscopic dimension. The nematic director field, coupled to the dispersed CNT long-axis, enables controlled director reorientation using well-established methods of LC alignment techniques, such as patterned-electrode-surface, electric fields, and magnetic fields. Electric field induced director rotation of a nematic LC+CNT system is of potential interests due to its possible applications as a nano electromechanical system. The relaxation mechanism for a LC+CNT composite, on the removal of the applied field, reveals the intrinsic dynamics of this anisotropic system. Dielectric hysteresis and temperature dependence of the dielectric constant coherently shows the ferroelectric-type behavior of the LC+CNT system in the nematic phase. The strong surface anchoring of LC molecules on CNT walls results in forming local isolated pseudo-nematic domains in the isotropic phase. These domains, being anisotropic, respond to external fields, but, do not relax back to the original state on switching of the field off, showing non-volatile memory effect.

Rajratan Basu; Germano S. Iannacchione

2009-05-07

426

A significant reduction of hysteresis in MnFe(P,Si) compounds  

NASA Astrophysics Data System (ADS)

The magnetocaloric effects in Mn1.3Fe0.7- x Co x P0.46Si0.54 compounds ( x = 0, 0.025, 0.05 and 0.1) were investigated systematically. X-ray diffraction shows that the compounds crystallize in the Fe2P-type hexagonal structure with space group P-62m symmetry. Magnetic measurements show that the paramagnetic-ferromagnetic transition temperatures range from 247 to 298 K. The maximal magnetic entropy changes in the Mn1.3Fe0.7P0.46Si0.54 compound reaches 8.3 J/kgK for a field change from 0 to 1.5 T. The thermal hysteresis of these compounds is less than 3 K. The maximum adiabatic temperature change is 2.2 K in Mn1.3Fe0.7P0.46Si0.54 and Mn1.3Fe0.65Co0.05P0.46Si0.54 compounds for a field change from 0 to 1.48 T, indicating this material system has potential for room-temperature magnetic refrigeration applications.

Huliyageqi, B.; Geng, Yao-xiang; Li, Ying-jie; Tegus, O.

2013-08-01

427

Planar dimers and Harnack curves  

E-print Network

In this paper we study the connection between dimers and Harnack curves discovered in math-ph/0311005. We prove that every Harnack curve arises as a spectral curve of some dimer model. We also prove that the space of Harnack curve of given degree is homeomorphic to a closed octant and that the areas of the amoeba holes and the distances between the amoeba tentacles give these global coordinates. We characterize Harnack curves of genus zero as spectral curves of isoradial dimers and also as minimizers of the volume under their Ronkin function with given boundary conditions.

Richard Kenyon; Andrei Okounkov

2003-11-05

428

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.

429

Crystallography on curved surfaces  

PubMed Central

We study static and dynamical properties that distinguish 2D crystals constrained to lie on a curved substrate from their flat-space counterparts. A generic mechanism of dislocation unbinding in the presence of varying Gaussian curvature is presented in the context of a model surface amenable to full analytical treatment. We find that glide diffusion of isolated dislocations is suppressed by a binding potential of purely geometrical origin. Finally, the energetics and biased diffusion dynamics of point defects such as vacancies and interstitials are explained in terms of their geometric potential. PMID:16894160

Vitelli, Vincenzo; Lucks, J. B.; Nelson, D. R.

2006-01-01

430

Lenses on curved surfaces.  

PubMed

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

Mitchell-Thomas, R C; Quevedo-Teruel, O; McManus, T M; Horsley, S A R; Hao, Y

2014-06-15

431

Curved cap corrugated sheet  

NASA Technical Reports Server (NTRS)

The report describes a structure for a strong, lightweight corrugated sheet. The sheet is planar or curved and includes a plurality of corrugation segments, each segment being comprised of a generally U-shaped corrugation with a part-cylindrical crown and cap strip, and straight side walls and with secondary corrugations oriented at right angles to said side walls. The cap strip is bonded to the crown and the longitudinal edge of said cap strip extends beyond edge at the intersection between said crown and said side walls. The high strength relative to weight of the structure makes it desirable for use in aircraft or spacecraft.

Davis, R. C.; Bales, T. T.; Royster, D. M.; Jackson, L. R. (inventors)

1984-01-01

432

Data Plotting and Curve Fitting in MATLAB Curve Fitting  

E-print Network

Data Plotting and Curve Fitting in MATLAB Curve Fitting Get the file pwl.dat from the class web(1)*pwl(:,1)+fit1(2)) If you're getting tired of typing pwl(:,1), etc., create new variables with shorter]') ylabel(`Output Current [mA]') title(`Curve Fitting Exercise') It is very important to always label your

Harrison, Reid R.

433

OP09O-OP404-9 Wide Field Camera 3 CCD Quantum Efficiency Hysteresis  

NASA Technical Reports Server (NTRS)

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.

Collins, Nick

2009-01-01

434

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

435

Attenuated total reflectance infrared spectroscopy study of hysteresis of water and n-alcohol coadsorption on silicon oxide.  

PubMed

The structure and thickness of the binary adsorbate layers formed on silicon oxide exposed in n-propanol/water and n-pentanol/water vapor mixtures under atmospheric pressure and room temperature conditions were investigated using attenuated total reflectance infrared spectroscopy (ATR-IR). The ATR-IR spectra of the adsorbate layers were analyzed while the vapor composition was varied stepwise by changing the mixing ratios of (a) n-propanol vapor stream with a 94% relative partial pressure (P/P(sat)) and 94% P/P(sat) water stream and (b) 83% P/P(sat)n-pentanol and 85% P/P(sat) water streams. The amount of the adsorbed water with solid-like structure in the binary adsorbate layer was larger in successive cycles of the water/alcohol vapor composition change, while n-alcohol showed negligible hysteresis in the amount adsorbed. The hysteresis behavior of the solid-like water structure was amplified in the coadsorption cycles of alcohol and water as compared to the water-only case. The origin of this behavior must be attributed to the structure of the alcohol/water binary adsorbate layer. The n-alcohol molecules present at the adsorbate/vapor interface can lower the surface energy of the system and stabilize the solid-like water structure in the alcohol-water binary adsorbate layer on silicon oxide. PMID:23098071

Barnette, Anna L; Kim, Seong H

2012-11-01

436

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

NASA Astrophysics Data System (ADS)

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

Barnard, Daniel J.; Hsu, David K.

2011-06-01

437

On planar rational cuspidal curves  

E-print Network

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 ...

Liu, Tiankai

2014-01-01

438

Curve walking in crayfish  

PubMed

Curve walking of crayfish Astacus leptodactylus was investigated by exploiting their optomotor response. The animal walked while spatially fixed on a motor-driven treadmill and turning behaviour was induced by an optical stimulus, a pattern consisting of vertical stripes moving in a horizontal direction. In this open-loop situation, the crayfish maintains the same step frequency for the legs on both sides of the body for low and intermediate turning speeds, but increases the step amplitude of the outer legs 2, 3 and 4 by shifting the posterior extreme position (PEP) of these legs in a posterior direction and reduces the step amplitude of inner leg 5 by shifting the PEP of this leg in an anterior direction. Furthermore, the main movement direction of the legs can change relative to the body. This was observed for outer leg 5 and also, at higher turning speeds, for outer leg 2. As coordinating influences between contra- and ipsilateral legs were found directly to influence only the anterior extreme position of the legs, these results indicate that the mechanisms controlling curve walking may be different from those controlling normal leg coordination. PMID:9319377

Cruse; Saavedra

1996-01-01

439

Static friction threshold effects on hysteresis and frequency spectra in rocks  

SciTech Connect

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

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

1999-06-01

440

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

PubMed

The industrial demand for machine tools with ever increasing speed and accuracy calls for a closer look at the physical phenomena that are present at small movements of those machine's slides. One of these phenomena, and probably the most dominant one, is the dependence of the friction force on displacement that can be described by a rate-independent hysteresis function with nonlocal memory. The influence of this highly nonlinear effect on the dynamics of the system has been theoretically analyzed in Part I of this paper. This part (II) aims at verifying these theoretical results on three experimental setups. Two setups, consisting of linearly driven rolling element guideways, have been built to specifically study the hysteretic friction behavior. The experiments performed on these specially designed setups are then repeated on one axis of an industrial pick-and-place device, driven by a linear motor and guided by commercial guideways. The results of the experiments on all the setups agree qualitatively well with the theoretically predicted ones and point to the inherent difficulty of accurate quantitative identification of the hysteretic behavior. They further show that the hysteretic friction behavior has a direct bearing on the dynamics of machine tools and its presence should therefore be carefully considered in the dynamic identification process of these systems. PMID:15836260

Symens, W; Al-Bender, F

2005-03-01

441

Hysteresis-based mechanism for the directed motility of the Ncd motor.  

PubMed

Ncd is a Kinesin-14 family protein that walks to the microtubule's minus end. Although available structures show its ?-helical neck in either pre- or post-stroke orientations, little is known about the transition between these two states. Using a combination of molecular dynamics simulations and structural analyses, we find that the neck sequentially makes intermediate contacts with the motor head along its mostly longitudinal path, and it develops a 24° twist in the post-stroke orientation. The forward (pre-stroke to post-stroke) motion has an ?4.5 k(B)T (where k(B) is the Boltzmann constant, and T=300 K) free-energy barrier and is a diffusion guided by the intermediate contacts. The post-stroke free-energy minimum is higher and is formed ?10° before reaching the orientation in the post-stroke crystal structure, consistent with previous structural data. The importance of intermediate contacts correlates with the existing motility data, including those for mutant Ncds. Unlike the forward motion, the recovery stroke goes nearly downhill in free energy, powered in part by torsional relaxation of the neck. The hysteresis in the energetics of the neck motion arises from the mechanical compliance of the protein, and together with guided diffusion, it may be key to the directed motility of Ncd. PMID:21889447

Lakkaraju, Sirish Kaushik; Hwang, Wonmuk

2011-09-01

442

Compositional, morphological, and hysteresis characterization of magnetic airborne particulate matter in Rome, Italy  

NASA Astrophysics Data System (ADS)

The magnetic properties of tree leaves may be used to delineate the abundance and dispersal of anthropogenic airborne particulate matter (PM) in urban environments. In the city of Rome, Italy, circulating vehicles are the main source of magnetic PM, already characterized as prevalently low-coercivity, magnetite-like particles. To further constrain the nature and origin of such magnetic particles, we carried out coupled field emission scanning electron microscopy and a variety of rock magnetic analyses on PM specimens from Quercus ilex leaves and from potential PM sources in circulating motor vehicles in Rome. Fe-rich particles are mostly 0.1-5 ?m in size, with irregular shapes and moss-like surface. Particles from disk brakes and diesel and gasoline exhaust pipes show distinct compositional and magnetic hysteresis signatures, suggesting that the magnetic PM collected on tree leaves consists of a mixture of particle populations deriving mostly from the abrasion of disk brakes and, to a lesser extent, from fuel combustion residuals emitted by diesel and gasoline exhausts. The contribution of fine superparamagnetic particles to the overall magnetic assemblage has been evaluated with specific rock magnetic analyses. The combined magnetic and microtextural-compositional analyses provide an effective and original tool to characterize urban PM air pollution.

Sagnotti, Leonardo; Taddeucci, Jacopo; Winkler, Aldo; Cavallo, Andrea

2009-08-01

443

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

NASA Astrophysics Data System (ADS)

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

Symens, W.; Al-Bender, F.

2005-03-01

444

Coexistence of phase transitions and hysteresis near the onset of Bose-Einstein condensation  

NASA Astrophysics Data System (ADS)

Multiple phases occurring in a Bose gas with finite-range interaction are investigated. In the vicinity of the onset of Bose-Einstein condensation (BEC), the chemical potential and the pressure show a van der Waals-like behavior indicating a first-order phase transition although there is no long-range attraction. Furthermore, the equation of state becomes multivalued near the BEC transition. For a Hartree-Fock or Popov (Hartree-Fock-Bogoliubov) approximation, such a multivalued region can be avoided by the Maxwell construction. For sufficiently weak interaction, the multivalued region can also be removed using a many-body T-matrix approximation. However, for strong interactions there remains a multivalued region even for the T-matrix approximation and after the Maxwell construction, which is interpreted as a density hysteresis. This unified treatment of normal and condensed phases becomes possible due to the recently found scheme to eliminate self-interaction in the T-matrix approximation, which allows one to calculate properties below and above the critical temperature.

Männel, M.; Morawetz, K.; Lipavský, P.

2013-05-01

445

Domain observations of titanomagnetites during hysteresis at elevated temperatures and thermal cycling  

NASA Astrophysics Data System (ADS)

Domain observations using Bitter patterns have been made on x = 0.6 titanomagnetites up to the Curie point. The principal results are: (1) there is no major increase in the number of domain walls before they are lost near the Curie point; (2) with increasing temperature, the fields at which saturation is reached and departed from during hysteresis decrease; (3) with increasing field, the temperatures at which saturation is reached during thermal cycling decrease; and (4) particles of the order of tens of microns were found to be in a saturated or near saturated state after cooling from the Curie point to room temperature in the ambient geomagnetic field. These results were observed on several different grains showing clear body domains. They attest to the predicted importance of the magnetostatic energy in the external field at elevated temperature. They also suggest that models of multidomain thermoremanent magnetization need not involve major increases in the number of walls at elevated temperature. Clearly the metastable single domain particles will be important in TRM due to the large moment they carry. Also discussed are the exotic patterns commonly found in titanomagnetites, and their possible role in determining magnetization state.

Metcalf, M.; Fuller, M.

1987-06-01

446

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

447

Numerical and experimental comparison of electromechanical properties and efficiency of HTS and ferromagnetic hysteresis motors  

NASA Astrophysics Data System (ADS)

Hysteresis motors are very attractive in a wide range of fractional power applications, due to its torque-speed characteristics and simplicity of construction. This motor's performance is expected to improve when HTS rotors are used, and in fact, hysteresis motors have shown to be probably the most viable electrical machines using HTS materials. While these motors, either conventional or HTS, are both hysteresis motors, they base their operation on different physical phenomena: hysteretic behaviour in conventional ferromagnetic materials is due to the material's non-linear magnetic properties, while in HTS materials the hysteresis has an ohmic nature and is related with vortices' dynamics. In this paper, theoretical aspects of both conventional and HTS hysteresis motors are discussed, its operation principles are highlighted, and the characteristics of both motors are presented. The characteristics, obtained both by experimental tests and numerical simulation (made with commercial software), are compared, in order to evaluate not only the motor's electromechanical performances but also the overall systems efficiency, including cryogenics for the HTS device.

Inácio, D.; Inácio, S.; Pina, J.; Gonçalves, A.; Ventim Neves, M.; Leão Rodrigues, A.

2008-02-01

448

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

Microsoft Academic Search

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

Tao Huang; John G. Duman

2002-01-01

449

Examples show system-performance upgrade  

SciTech Connect

This paper reviews several techniques to quantify the performance of a turboexpander refrigeration system's expander and compressor. It proposes that improvements in cycle efficiency can best be implemented through a combined effort of those responsible for the operation of the gas processing plant and the design engineers familiar with the performance of the specialized components within the system. It points out that the manufacturers of the turbomachinery should be able to recommend specific changes to improve performance and quantify the net benefits these changes have on plant efficiency. It presents graphs showing the effect of heat exchanger fouling, performance loss, and cost of lost performance. It attempts to operate a compressor at a higher efficiency on its efficiency vs. Q/N (flow rate/shaft speed) performance curve and explains that operating curves can be prepared based on field-measured values.

McIntire, R.

1982-07-12

450

Ironing Out Curves  

NSDL National Science Digital Library

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.

451

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

452

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

SciTech Connect

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.

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

453

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

SciTech Connect

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.

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

454

13. VIEW OF DRIVE TRAIN, SHOWING TWO PINIONS ENGAGING DOUBLE ...  

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

13. VIEW OF DRIVE TRAIN, SHOWING TWO PINIONS ENGAGING DOUBLE CURVED RACK. - Chicago, Milwaukee & St. Paul Railway, Bridge No. Z-6, Spanning North Branch of Chicago River, South of Cortland Street, Chicago, Cook County, IL

455

Physiological thermoregulation in a crustacean? Heart rate hysteresis in the freshwater crayfish Cherax destructor.  

PubMed

Differential heart rates during heating and cooling (heart rate hysteresis) are an important thermoregulatory mechanism in ectothermic reptiles. We speculate that heart rate hysteresis has evolved alongside vascularisation, and to determine whether this phenomenon occurs in a lineage with vascularised circulatory systems that is phylogenetically distant from reptiles, we measured the response of heart rate to convective heat transfer in the Australian freshwater crayfish, Cherax destructor. Heart rate during convective heating (from 20 to 30 degrees C) was significantly faster than during cooling for any given body temperature. Heart rate declined rapidly immediately following the removal of the heat source, despite only negligible losses in body temperature. This heart rate 'hysteresis' is similar to the pattern reported in many reptiles and, by varying peripheral blood flow, it is presumed to confer thermoregulatory benefits particularly given the thermal sensitivity of many physiological rate functions in crustaceans. PMID:15313496

Goudkamp, Jacqueline E; Seebacher, Frank; Ahern, Mark; Franklin, Craig E

2004-07-01

456

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

PubMed

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

Manor, Ofer

2014-06-17

457

Hysteresis between coral reef calcification and the seawater aragonite saturation state  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

458

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

SciTech Connect

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.

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

2008-10-14

459

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

460

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

461

ALMOST-COMPLEX CURVES IN S6 AND SPECTRAL CURVES  

Microsoft Academic Search

There are three types of almost-complex curves in the nearly-Kahler 6- sphere: they are totally geodesic, pseudo-holomorphic or superconformal, the last case being generic. This paper concerns superconformal almost-complex curves. We begin by giving a geometric construction of a particularly natural G2-framing for such curves. This framing can easily be shown to agree with that in (6); the exposition here

EMMA CARBERRY

462

Curve Matching by using B-spline Curves  

Microsoft Academic Search

This paper presents an algorithm for estimating the control points of the B-spline and curve matching which is achieved by using the dissimilarity measure based on the knot associated with the B-spline curves. The B-splines stand as one of the most efficient curve representations and possess very attractive properties such as spatial uniqueness, boundedness and continuity, local shape controllability, and

Tet Toe; Tang Van To

463

Generalized manifolds in products of curves  

E-print Network

The intent of this article is to study some special $n$-dimensional continua lying in products of $n$ curves. (The paper is an improved version of a portion of \\cite{K-K-S}.) We show that if $X$ is a locally connected, so-called, quasi $n$-manifold lying in a product of $n$ curves