This chapter presents benefits of noise in hysteretic systems by using the framework developed in the previous chapters. While it is mostly seen as a disruptive effect, noise can also have a constructive role by helping a system to...
moreThis chapter presents benefits of noise in hysteretic systems by using the framework developed in the previous chapters. While it is mostly seen as a disruptive effect, noise can also have a constructive role by helping a system to overcome a barrier in various activation processes, by providing some degree of randomness useful in audio or visual perceptions, or by activating some kind of resonance response in nonlinear systems. These aspects are introduced and intuitively explained while providing a short overview of key results obtained in this area. Although the applications of noise benefits spread over many areas, from climatology and signal processing to nanotechnology and neuroscience, most of the studies can be theoretically framed into two-state models or simple variants thereof, while complex multi-stable systems are rarely addressed. The major contribution of this chapter is to provide a unitary framework for studying constructive effects of arbitrary colored noise in complex hysteretic systems and its implementation in HysterSoft©. Several examples are discussed following the line of the recent articles published by our group.
RFID location systems for indoor and outdoor positioning are a promise for the future, even the performances of these systems are affected by many factors. We identified here that for a system working in the RF band near 900 MHz, the...
moreRFID location systems for indoor and outdoor positioning are a promise for the future, even the performances of these systems are affected by many factors. We identified here that for a system working in the RF band near 900 MHz, the objects interposed between the antenna system and the tags to be located may have a great influence in terms of accuracy of the measurement results. In closed areas multiple reflection paths may disturb the measurement systems, a percent of only 40 to 60 of total measurements are enough accurate to locate an object. In such conditions, there are small chances for this kind of systems to be used for high precision indoor applications requiring more than several tens of centimetres accuracy. The results obtained from the measurements we made in open area test sites are more promising, more than 93 percent of total result were not affected by notable errors. For speed measurement of mobile objects by using RFID systems, we may conclude there are many aspec...
A novel design for a mechanical-electrical transducer is presented in this article along with the preliminary testing of the transducer prototype. By using a Polaroid optocoupler as the motion sensor, this device combines the transducer...
moreA novel design for a mechanical-electrical transducer is presented in this article along with the preliminary testing of the transducer prototype. By using a Polaroid optocoupler as the motion sensor, this device combines the transducer feature to convert mechanical signals to electrical ones with the optoisolator feature of galvanic separation between two voltage modules. Signal conditioning circuit is a current-to-frequency converter, while the obtained signals are logically compatible and can be processed by a microprocessor. The device is aimed for application in the areas of automation and mechatronics.
ABSTRACT In spin crossover (SCO) systems, the shape of the hysteresis curves are closely related to the interactions between the molecules, which these play an important role in the response of the system to an external parameter. The...
moreABSTRACT In spin crossover (SCO) systems, the shape of the hysteresis curves are closely related to the interactions between the molecules, which these play an important role in the response of the system to an external parameter. The effects of short-range interactions on the different shape of the spin transition phenomena were investigated. In this contribution we solve the corresponding Hamiltonian for a three-dimensional SCO system taking into account short-range and long-range interaction using a biased Monte Carlo entropic sampling technique and a semi-analytical method. We discuss the competition between the two interactions which governs the low spin (LS) - high spin (HS) process for a three-dimensional network and the cooperative effects. We demonstrate a strong correlation between the shape of the transition and the strength of short-range interaction between molecules and we identified the role of the size for SCO systems.
Mechanical-electrical optoisolator transducers are position transducers which use as a sensor, a Polaroid optocoupler specialized in converting rotation and/or translation movements into electrical signals. The used sensor is an analog...
moreMechanical-electrical optoisolator transducers are position transducers which use as a sensor, a Polaroid optocoupler specialized in converting rotation and/or translation movements into electrical signals. The used sensor is an analog device whose transfer characteristic is non-linear. In this article is presented a method of linearizing this new type sensors’s characteristic. The method is based on the analysis of the physical processes which take place within the Polaroid optocoupler. The mechanical-electrical optoisolator transducer allows the extraction of the signals out of the areas with intense electromagnetic field. Being an analog linear transducer, the signal generated by it doesn’t impose the use of a microprocessor. This thing permits to obtain some systems of checking the position of a machine-tool’s components at a low cost price.
This article presents a theoretical prediction of stochastic resonance in spin-crossover materials. The analysis of stochastic resonance phenomenon in a spin-crossover system is performed in the framework of the phenomenological kinetic...
moreThis article presents a theoretical prediction of stochastic resonance in spin-crossover materials. The analysis of stochastic resonance phenomenon in a spin-crossover system is performed in the framework of the phenomenological kinetic model with light-induced transition described by dynamical potential in terms of the Lyapunov functions. By using numerical simulation of stochastic trajectories with white- and colored-noise action, the evaluation of stochastic resonance is carried out by signal-to-noise ratio of the system output. The corresponding signal-to-noise ratio features a two-peak behavior which is related to the asymmetric shape of the dynamic potential. For the case of the Ornstein-Uhlenbeck process, the variations of resonance condition with respect to different autocorrelation times are additionally studied.
This paper presents the framework of cyberinfrastructure and the state of the art in this area of research, as well as a preliminary analysis of a our university network capabilities for remote visualization and high performance...
moreThis paper presents the framework of cyberinfrastructure and the state of the art in this area of research, as well as a preliminary analysis of a our university network capabilities for remote visualization and high performance computing. References are made to the cyber-tools and methods, such as high-performance computing, communication technologies, and simulation models, enabling progress in cyberinfrastructure development. The
ABSTRACT In the current study we report on the unusual results obtained in the framework of the atom-phonon coupling model: two metastables states at low temperatures. These results can explain the experimental results reported by Ould...
moreABSTRACT In the current study we report on the unusual results obtained in the framework of the atom-phonon coupling model: two metastables states at low temperatures. These results can explain the experimental results reported by Ould Moussa et al. [9] and Matsumoto et al. [10] . This type of SCO behavior is due to the competition between the Light-Induced Excited Spin State Trapping (LIESST) effect, the elastic inter- action between the molecules and the thermal activation. In order to determine the stability of the states founded at low temperature, the free energy F is presented for the case of the two step spin transition of a SCO compound
ABSTRACT This paper presents the results of the analysis of Polaroid optocoupler mechanical-electrical sensor static characteristics. Our paper achieves analysis on distance adjustment Polaroid optocouplers of LED-photoresistor and...
moreABSTRACT This paper presents the results of the analysis of Polaroid optocoupler mechanical-electrical sensor static characteristics. Our paper achieves analysis on distance adjustment Polaroid optocouplers of LED-photoresistor and LED-phototransistor types. These optocouplers analysis was performed in two distinct cases by using 0.2 mm and 0.7 mm thick Polaroid filters. At present, this Polaroid optocoupler mechanical-electrical sensor is only a prototype.
ABSTRACT Mechanical-electrical Optoisolator Transducers are Polaroid optocouplers whose main function is to convert a rotational and/or a translation movement into electrical signal. These devices combine transducers feature to connect...
moreABSTRACT Mechanical-electrical Optoisolator Transducers are Polaroid optocouplers whose main function is to convert a rotational and/or a translation movement into electrical signal. These devices combine transducers feature to connect two physical systems operating with signals of different nature, with optocouplers feature of galvanic separation of two different voltage modules. This is achieved by introducing a mechanically controlled system of Polaroid filters on the light beam path performing the optical coupling. These transducers are generally suitable for automation and mecatronics applications.
... Octavian Modest MANU1, Mihai DIMIAN1, Ioan DUMITRU2, Adrian GRAUR1 1 Dept. of Electrical Engineering and Computer Science, Stefan cel Mare University of Suceava, Romania
octavianm@eed.usv.ro 2 Dept. of Physics, Alexandru Ioan Cuza...
more... Octavian Modest MANU1, Mihai DIMIAN1, Ioan DUMITRU2, Adrian GRAUR1 1 Dept. of Electrical Engineering and Computer Science, Stefan cel Mare University of Suceava, Romania
octavianm@eed.usv.ro 2 Dept. of Physics, Alexandru Ioan Cuza University of Iasi ...
ABSTRACT This paper presents a novel approach to studying electronics disciplines in technical educational programs based on a Mobile Studio Laboratory paradigm developed at the Rensselaer Polytechnic Institute. Several implementations...
moreABSTRACT This paper presents a novel approach to studying electronics disciplines in technical educational programs based on a Mobile Studio Laboratory paradigm developed at the Rensselaer Polytechnic Institute. Several implementations are discussed and a comparative analysis between the Mobile Studio laboratories and the current standard ones is presented. This new educational approach provides an interactive technology - enhanced learning environment as well as a high level of individual experimentation both inside and outside the classrooms. As a result, theoretical concepts can be explain in an easy-to-grasp manner during the lecture by using the studio format while simultaneous individual experiments also allow the students to better understand the experimental deviations and the practical implications of the discussed theory. Although this solution lacks some of the characteristics and quality of modern laboratory measuring equipments it comes with a much lower cost and space needs and a much higher degree of mobility, being accessible to almost any student, anytime and anywhere.
ABSTRACT A study of thermal behavior for two-dimensional spin-crossover compounds is performed by using an Ising-like model including both short-range and long-range interactions and a Monte Carlo entropic sampling technique for...
moreABSTRACT A study of thermal behavior for two-dimensional spin-crossover compounds is performed by using an Ising-like model including both short-range and long-range interactions and a Monte Carlo entropic sampling technique for determining the associated density of states. The effects of various factors, such as external pressure, internal interaction strength or system size, on the thermal transition are analyzed and compared to several experimental findings in this area. The study is focused on two-step transitions and the conditions for hysteresis behavior at each step which are especially important for the potential applications of spin-crossover materials in data storage devices or smart sensors.
ABSTRACT The spin – crossover compounds (SCO) have become of great interest recently due to their potential applications in memories, sensors, switches, and display devices. These materials are particularly interesting because upon...
moreABSTRACT The spin – crossover compounds (SCO) have become of great interest recently due to their potential applications in memories, sensors, switches, and display devices. These materials are particularly interesting because upon application of heat, light, pressure or other physical stimulus, they feature a phase transition between a low-spin (LS) diamagnetic ground state and a high-spin (HS) paramagnetic state, accompanied in some cases by color change. The phase transition can be discontinuous (with hysteresis), in two steps or gradual. Our analysis is performed by using the atom – phonon coupling (APC) model which considers that neighboring molecules are connected through a spring characterized by an elastic constant depending on molecules electronic state. By associating a fictitious spin to each molecule that has -1 and +1 eigenvalues corresponding to LS and HS levels respectively, an Ising type model can be developed for the analysis of metastable states and phase transitions in spin-crossover compounds. This contribution is aimed at providing a review of our recent results in this area, as well as novel aspects related to SCO compounds behavior at low temperature. In the framework of the APC model, we will discuss a bout the existence of metastable and unstable states, phase transitions and hysteresis phenomena, as well as their dependence on sample size.
ABSTRACT 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...
moreABSTRACT 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.
ABSTRACT The mixed hysteresis behavior of counter-clockwise and clockwise loops has recently attracted the attention of the magnetics community, due to several experimental findings in inhomogeneous and hetero-structure magnetic systems....
moreABSTRACT The mixed hysteresis behavior of counter-clockwise and clockwise loops has recently attracted the attention of the magnetics community, due to several experimental findings in inhomogeneous and hetero-structure magnetic systems. Various hybrid models are proposed here to address this behavior based on the superposition of standard hysteresis models and their newly developed clockwise variants. A special attention is also devoted to Bouc-Wen model, a typical clockwise often used by applied mechanics community, and to its relevance for mixed hysteresis. These clockwise and hybrid models have been implemented in an open-access academic software and their performance is illustrated by examples of hysteretic loops, first order reversal curves and diagrams simulated in this framework.
ABSTRACT The “inverse problem” approach to the analysis of precessional switching of magnetization in perpendicular media is presented. This approach is purely algebraic in nature, and it leads to the direct calculations of expressions...
moreABSTRACT The “inverse problem” approach to the analysis of precessional switching of magnetization in perpendicular media is presented. This approach is purely algebraic in nature, and it leads to the direct calculations of expressions for magnetic-field pulses that guarantee the precessional switching. The effectiveness of the developed technique is illustrated by examples.
The ``inverse problem'' approach to the analysis of precessional switching of magnetization in thin films is presented. This approach leads to the explicit expressions for magnetic field pulses that guarantee the...
moreThe ``inverse problem'' approach to the analysis of precessional switching of magnetization in thin films is presented. This approach leads to the explicit expressions for magnetic field pulses that guarantee the precessional switching. The effectiveness of the developed technique is illustrated by examples.
ABSTRACT The multiscale approach to the magnetization dynamics driven by external magnetic fields is presented. In this approach, the Landau-Lifshitz equations are represented in an equivalent form, where the magnetic free energy is used...
moreABSTRACT The multiscale approach to the magnetization dynamics driven by external magnetic fields is presented. In this approach, the Landau-Lifshitz equations are represented in an equivalent form, where the magnetic free energy is used as one of the state variables. This form clearly separates fast and slow dynamics and, consequently, it can be used for the development of perturbation and multiple scale techniques. Several applications of this approach to the precessional magnetization switching are discussed.
Anisotropy characterization of garnet films is important for the proper utilization of these films. Usually, ferromag-netic resonance1 or optical2 measurements are used for this purpose, but the required experimental techniques are highly...
moreAnisotropy characterization of garnet films is important for the proper utilization of these films. Usually, ferromag-netic resonance1 or optical2 measurements are used for this purpose, but the required experimental techniques are highly complex. In this article, we ...
The analytical solutions to the LandauLifshitz equation for damping and precessional switchings of materials with uniaxial anisotropy are found. These solutions lead to the expressions for the switching times and critical fields....
moreThe analytical solutions to the LandauLifshitz equation for damping and precessional switchings of materials with uniaxial anisotropy are found. These solutions lead to the expressions for the switching times and critical fields. Comparison of these two distinct ...
ABSTRACT Noise is mainly seen as a disruptive effect and poses fundamental limits for further improvements of various technologies, such as magnetic data storage. However, noise can also play a constructive role in nonlinear systems,...
moreABSTRACT Noise is mainly seen as a disruptive effect and poses fundamental limits for further improvements of various technologies, such as magnetic data storage. However, noise can also play a constructive role in nonlinear systems, activating some kind of resonance response. Here, it is proved that various hysteretic systems can exhibit such noise induced amplification of the system response. The quantities used in our study to characterize this behavior are signal amplification and signal-to-noise ratio, which displays a maximum at the resonant noise strength. The resulting statistical technique that includes various algebraic, differential, and integral models of hysteresis have been implemented in freely available academic software.
The precessional switching process of a uniformly magnetized thin film with in-plane anisotropy subject to pulsed magnetic fields applied in the film plane is analyzed. Critical fields required to achieve switching are studied for the...
moreThe precessional switching process of a uniformly magnetized thin film with in-plane anisotropy subject to pulsed magnetic fields applied in the film plane is analyzed. Critical fields required to achieve switching are studied for the case when the applied field is constant during the pulse duration and forms arbitrary angles with the hard axis. By using two integrals of magnetization
ABSTRACT A new hysteresis model is developed to describe clockwise hysteresis, in which the positive saturation is achieved for positive values of the input. The model is based on the traditional (counter-clockwise) Jiles-Atherton (JA)...
moreABSTRACT A new hysteresis model is developed to describe clockwise hysteresis, in which the positive saturation is achieved for positive values of the input. The model is based on the traditional (counter-clockwise) Jiles-Atherton (JA) model and describes the input-output relation in the form of a first-order differential equation. The most important characteristics such as initial susceptibility, coercive fields, remanence, thermal stability, first and higher order reversal curves are discussed. A comparison with other two clockwise hysteresis models of hysteresis (i.e., the Preisach and Bouc-Wen models) is provided. It is proven that the clockwise JA model can describe novel hysteretic behavior that cannot be reproduced by the previous two models. The novel model is also appealing due its relatively simple numerical implementation and its small number of parameters.
A globally convergent iterative technique for the solution of nonlinear magnetostatic problems is described. This technique can be naturally implemented by using the fast multipole method. In this technique, all computations are confined...
moreA globally convergent iterative technique for the solution of nonlinear magnetostatic problems is described. This technique can be naturally implemented by using the fast multipole method. In this technique, all computations are confined to the region occupied by ferromagnetic objects. For this reason, this technique may emerge as a viable alternative to the finite-element method. Numerical examples that highlight the
A unitary framework for the analysis of noise induced phenomena in complex hysteretic systems is developed and implemented in an open-access academic software. Various differential, integral, and algebraic models of hysteresis are...
moreA unitary framework for the analysis of noise induced phenomena in complex hysteretic systems is developed and implemented in an open-access academic software. Various differential, integral, and algebraic models of hysteresis are considered while the input processes are generated from arbitrary given spectra. The statistical algorithm based on Monte-Carlo techniques and used to compute the stochastic characteristics of hysteretic systems
ABSTRACT The temperature driven phase transition occurring in spin crossover nanochains has been studied by an Ising-like model considering both short-range and long-range interactions. Various types of spin crossover profiles have been...
moreABSTRACT The temperature driven phase transition occurring in spin crossover nanochains has been studied by an Ising-like model considering both short-range and long-range interactions. Various types of spin crossover profiles have been described in this framework, including a novel three-step transition identified in a nanosystem with eight molecules, which is modeled for the first time. A special interest has been also given to stepwise transitions accompanied by two hysteresis loops. The edge and size effects on spin crossover behavior have been investigated in order to get a deeper insight of the underlying mechanisms involved in these unusual spin transitions.
Relation between noise and hysteresis has been recently under intensive research focus due to the fundamental challenges posed by noise and fluctuations in ultrasmall semiconductor and magnetic devices. However, a systematic analysis of...
moreRelation between noise and hysteresis has been recently under intensive research focus due to the fundamental challenges posed by noise and fluctuations in ultrasmall semiconductor and magnetic devices. However, a systematic analysis of hysteretic materials and devices driven by noisy input has been rather limited. On the one hand, this situation is related to lack of general analytical tools for
