Search results for "HYSTERESIS"

Multilayer Sequential Assembly of Thin Films That Display Room-Temperature Spin Crossover with Hysteresis

2006

Spin canting in Re(IV) complexes: magnetic properties of [ReX4(bpym)] ( X = Cl and Br; bpym = 2,2′-bipyrimidine)

2008

The mononuclear complexes [ReCl4(bpym)] (1) and [ReBr4(bpym)] (2) (bpym = 2,2′-bipyrimidine) are weak ferromagnets. Magnetic ordering occurs below 7.0 (1) and 20.0 K (2) and good hysteresis loops are observed for the two compounds at 2.0 K. A spin-canting phenomenon, i.e., a non-strict linearity of the individual spins aligned in an anti-parallel way by intermolecular antiferromagnetic coupling occurring in many Re(IV) complexes, accounts for these magnetic features which are unusual in molecular solids such as 1 and 2.

Hysteresis and frequency tunability of gyrotrons

2015

We present the first devoted experimental and theoretical study of hysteresis phenomenon in relation to frequency tunability of gyrotrons.

Pressure effect on temperature induced high-spin–low-spin phase transitions

2002

The effect of hydrostatic pressure on the transition temperature and the hysteresis widths of first-order spin crossover phase transitions is considered in the frame of the mean field theory and on the basis of the scope of recent pressure experiments. Relevant parameters for a qualitative description of the behaviour of spin transition compounds under pressure are derived and analysed.

Description of Hysteresis in Lithium Battery by Classical Preisach Model

2012

In this paper Preisach Model is applied to obtain a mathematical model of the hysteresis in lithium battery. Preisach Model allows to describe the hysteresis of charging and discharging cycles in a lithium battery. The identification of the model is obtained by using a neural network technique developed for magnetic systems. The model is verified on some experimental tests on commercial batteries.

Firefly optimization used to identify hysteresis parameter on rotational MR-damper

2014

In his paper the physical properties and mathematical models of a semi-active magnetorheological (MR) damper is studied. The considered models are the Dahl model and Bouc-Wen model. The parameters for these models are found by using a firefly optimization algorithm that minimizes the difference between experimental and simulated data. The objective of his paper is to compare different mathematical MR-damper models with the experimental data. The simulation results illustrate he effectiveness of he proposed optimization algorithm.

Molecular mechanism of capillary condensation of acetonitrile vapor on MCM-41 with the aid of a time-correlation function analysis of IR spectroscopy

1998

Abstract The adsorption isotherm and IR spectra of acetonitrile adsorbed on MCM-41 (pore-width=3.2 nm) were measured at 303 K. The adsorption isotherm had a sharp jump at P / P 0 =0.3 without adsorption hysteresis. The CN stretching ν 2 -band of adsorbed acetonitrile had two-component α- and β-bands at 2263 and 2254 cm −1 , respectively, assigned to hydrogen-bonded molecules on surface hydroxyls of MCM-41 and physisorbed molecules in mesopores whose walls are coated with hydrogen-bonded molecules, respectively. The β-band was analyzed with a time correlation function, giving a reorientation time τ . The τ value of the adsorbed molecule before capillary condensation was smaller than that of …

Identification of parameters of the Jiles-Atherton model by neural networks

2011

In this paper a procedure for the identification of the parameters of the Jiles–Atherton (JA) model is presented. The parameters of the JA model of a material are found by using a neural network trained by a collection of hysteresis curves, whose parameters are known. After a presentation of the Jiles–Atherton model, the neural network and the training procedure are described and the method is validated by using some numerical, as well as experimental, data.

Hemivariational Inequalities and Hysteresis

2001

Hemivariational inequalities introduced by P.D. Panagiotopoulos are generalizations of variational inequalities. This type of inequality problems arises, e.g. in variational formulation of mechanical problems whenever nonmonotone and multivalued relations or nonconvex energy functions are involved. Typical examples of such kind of phenomena are nonmonotone friction laws and adhesive contact laws. Mathematically these nonmonotone relations are described by means of generalized gradients (in sense of F.H. Clarke) of nonconvex potential functions. For applications and for their mathematical treatment we refer to [9],[10],[13]–[18].

Tuning the spin crossover above room temperature: iron(II) complexes of substituted and deprotonated 2,6-bis(benzimidazol-2-yl)pyridine

2005

Abstract The complex [Fe(tzimpy)2](ClO4)2 · 2H2O (tzimpy = 2,4,6-tris-(benzimidazol-2-yl)pyridine) shows an abrupt spin crossover (S = 0–2 transition) above room temperature centered at Tc = 323 K with a hysteresis width of ΔT = 35 K. The neutral iron(II) complex with deprotonated bzimpy ligands (bzimpy = 2,6-bis(benzimidazol-2-yl)pyridine) exhibits a gradual spin transition on the first heating with Tc = 424 K. There are irreversible changes between T = 503 and 523 K: the liberation of the crystal water, the color change (blue–green) followed by a structure change. Next thermal cycles are reproducible though, heating/cooling paths are different from the first heating.