scholarly journals Universal phase dynamics in VO2 switches revealed by ultrafast operando diffraction

Science ◽  
2021 ◽  
Vol 373 (6552) ◽  
pp. 352-355
Author(s):  
Aditya Sood ◽  
Xiaozhe Shen ◽  
Yin Shi ◽  
Suhas Kumar ◽  
Su Ji Park ◽  
...  
Keyword(s):  
Time Scales ◽  
Metastable Phase ◽  
Dynamical Behavior ◽  
Electrical Excitation ◽  
Time Resolved ◽  
Fundamental Limits ◽  
Phase Dynamics ◽  
Transformation Pathway ◽  
Equilibrium Phases ◽  
Device Operation

Understanding the pathways and time scales underlying electrically driven insulator-metal transitions is crucial for uncovering the fundamental limits of device operation. Using stroboscopic electron diffraction, we perform synchronized time-resolved measurements of atomic motions and electronic transport in operating vanadium dioxide (VO2) switches. We discover an electrically triggered, isostructural state that forms transiently on microsecond time scales, which is shown by phase-field simulations to be stabilized by local heterogeneities and interfacial interactions between the equilibrium phases. This metastable phase is similar to that formed under photoexcitation within picoseconds, suggesting a universal transformation pathway. Our results establish electrical excitation as a route for uncovering nonequilibrium and metastable phases in correlated materials, opening avenues for engineering dynamical behavior in nanoelectronics.

scholarly journals A Survey of Function Analysis and Applied Dynamic Equations on Hybrid Time Scales

Entropy ◽  
2021 ◽  
Vol 23 (4) ◽  
pp. 450
Author(s):  
Chao Wang ◽  
Ravi P. Agarwal
Keyword(s):  
Time Scales ◽  
Function Analysis ◽  
Dynamical Behavior ◽  
Research Field ◽  
Dynamic Equations ◽  
Future Research ◽  
Dynamical Models ◽  
Time Scale Calculus ◽  
The Difference

As an effective tool to unify discrete and continuous analysis, time scale calculus have been widely applied to study dynamic systems in both theoretical and practical aspects. In addition to such a classical role of unification, the dynamic equations on time scales have their own unique features which the difference and differential equations do not possess and these advantages have been highlighted in describing some complicated dynamical behavior in the hybrid time process. In this review article, we conduct a survey of abstract analysis and applied dynamic equations on hybrid time scales, some recent main results and the related developments on hybrid time scales will be reported and the future research related to this research field is discussed. The results presented in this article can be extended and generalized to study both pure mathematical analysis and real applications such as mathematical physics, biological dynamical models and neural networks, etc.

scholarly journals Time Resolved Emission of Sidestream Smoke Particles

1992 ◽  
Vol 15 (2) ◽  
pp. 53-57
Author(s):  
R Dittmann ◽  
HJ Feld ◽  
BH Müller ◽  
W Schneider
Keyword(s):  
Time Scales ◽  
Time Resolved ◽  
Smoke Particles ◽  
Sidestream Smoke ◽  
Different Types ◽  
Short Time ◽  
Aerosol Properties

AbstractBy means of the dispersion quotient method, the aerosol properties of freshly produced sidestream smoke were measured during the puff and subsequent interpuff period. These measurements were made on short time scales and at high aerosol concentrations. Examples are presented, which show the influence of different combustion conditions during the puff (resulting from different degrees of ventilation and different types of tobacco) on the emission of sidestream particles during the interpuff period. The ratio of the volume concentrations of the particles before and during a puff is reduced by ventilation and is nearly unchanged by the variation of the tobacco type.

scholarly journals Non-steady wind turbine response to daytime atmospheric turbulence

2017 ◽  
Vol 375 (2091) ◽  
pp. 20160103 ◽  
Author(s):  
Tarak N. Nandi ◽  
Andreas Herrig ◽  
James G. Brasseur
Keyword(s):  
Field Experiment ◽  
Wind Turbine ◽  
Atmospheric Turbulence ◽  
Time Scales ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Atmospheric Conditions ◽  
Time Resolved ◽  
Eddy Simulation ◽  
Large Eddy

Relevant to drivetrain bearing fatigue failures, we analyse non-steady wind turbine responses from interactions between energy-dominant daytime atmospheric turbulence eddies and the rotating blades of a GE 1.5 MW wind turbine using a unique dataset from a GE field experiment and computer simulation. Time-resolved local velocity data were collected at the leading and trailing edges of an instrumented blade together with generator power, revolutions per minute, pitch and yaw. Wind velocity and temperature were measured upwind on a meteorological tower. The stability state and other atmospheric conditions during the field experiment were replicated with a large-eddy simulation in which was embedded a GE 1.5 MW wind turbine rotor modelled with an advanced actuator line method. Both datasets identify three important response time scales: advective passage of energy-dominant eddies (≈25–50 s), blade rotation (once per revolution (1P), ≈3 s) and sub-1P scale (<1 s) response to internal eddy structure. Large-amplitude short-time ramp-like and oscillatory load fluctuations result in response to temporal changes in velocity vector inclination in the aerofoil plane, modulated by eddy passage at longer time scales. Generator power responds strongly to large-eddy wind modulations. We show that internal dynamics of the blade boundary layer near the trailing edge is temporally modulated by the non-steady external flow that was measured at the leading edge, as well as blade-generated turbulence motions. This article is part of the themed issue ‘Wind energy in complex terrains’.

ALLOY PHASE FORMATION BY MECHANICAL ALLOYING: CONSTRAINTS AND MECHANISMS

1992 ◽  
Vol 06 (03) ◽  
pp. 127-138 ◽  
Author(s):  
E. MA ◽  
M. ATZMON
Keyword(s):  
Mechanical Alloying ◽  
Phase Formation ◽  
Single Phase ◽  
Metastable Phase ◽  
Interfacial Free Energy ◽  
Metastable Equilibrium ◽  
Heat Of Mixing ◽  
Layered Composites ◽  
Two Phase ◽  
Equilibrium Phases

Alloy phase formation in binary metallic systems by mechanical alloying (MA) of elemental powders is briefly reviewed. Our recent results indicate the inadequacy of the current understanding of the MA process, which has been depicted as an isothermal solid-state interdiffusion reaction under interfacial, metastable, equilibrium in layered composites. A structural and thermodynamic analysis of the supersaturation followed by amorphization in the Zr-Al system demonstrates that a system can be constrained to be a single phase without reaching two-phase (metastable) equilibrium during MA. Alloying, resulting in a single metastable phase, has also been achieved in immiscible systems with positive heat of mixing, such as Fe-Cu. In both cases, the interfacial free energy associated with a repeatedly deformed, fine-structured, two-phase alloy appears to pose polymorphous constraints. In addition, equilibrium phases can be formed during MA in an exothermic, self-sustained fashion, as observed for the formation of AlNi. Al-Ni phases formed under different milling conditions suggest that self-sustained reactions may occur, undetected, on a grain-by-grain basis.

POPULATION GROWTH MODELING WITH BOOM AND BUST PATTERNS: THE IMPULSIVE DIFFERENTIAL EQUATION FORMALISM

2015 ◽  
Vol 23 (supp01) ◽  
pp. S135-S149 ◽  
Author(s):  
FERNANDO CÓRDOVA-LEPE ◽  
GONZALO ROBLEDO ◽  
JAVIER CABRERA-VILLEGAS
Keyword(s):  
Differential Equation ◽  
Population Dynamics ◽  
Time Scales ◽  
Chaotic Dynamics ◽  
Impulsive Differential Equation ◽  
Dynamical Behavior ◽  
Single Species ◽  
Open Problems ◽  
Boom And Bust ◽  
Different Time Scales

This note gives an overview on basic mathematical models describing the population dynamics of a single species whose vital dynamics has different time scales. We present five cases combining two time–scales with Malthusian growth in at least one scale. The dynamical behavior shows a progressive complexity, from "naive" to chaotic dynamics (in the Li–Yorke's sense). In addition, some open problems and new results are presented.

scholarly journals Structural photoactivation of a full-length bacterial phytochrome

2016 ◽  
Vol 2 (8) ◽  
pp. e1600920 ◽  
Author(s):  
Alexander Björling ◽  
Oskar Berntsson ◽  
Heli Lehtivuori ◽  
Heikki Takala ◽  
Ashley J. Hughes ◽  
...  
Keyword(s):  
Time Scales ◽  
Conformational Changes ◽  
Structural Changes ◽  
Deinococcus Radiodurans ◽  
Full Length ◽  
Photon Absorption ◽  
Signaling Mechanism ◽  
Time Resolved ◽  
Binding Domains ◽  
Sensor Proteins

Phytochromes are light sensor proteins found in plants, bacteria, and fungi. They function by converting a photon absorption event into a conformational signal that propagates from the chromophore through the entire protein. However, the structure of the photoactivated state and the conformational changes that lead to it are not known. We report time-resolved x-ray scattering of the full-length phytochrome from Deinococcus radiodurans on micro- and millisecond time scales. We identify a twist of the histidine kinase output domains with respect to the chromophore-binding domains as the dominant change between the photoactivated and resting states. The time-resolved data further show that the structural changes up to the microsecond time scales are small and localized in the chromophore-binding domains. The global structural change occurs within a few milliseconds, coinciding with the formation of the spectroscopic meta-Rc state. Our findings establish key elements of the signaling mechanism of full-length bacterial phytochromes.

scholarly journals Time-resolved magnetic relaxation of a nanomagnet on subnanosecond time scales

2012 ◽  
Vol 85 (22) ◽  
Author(s):  
H. Liu ◽  
D. Bedau ◽  
J. Z. Sun ◽  
S. Mangin ◽  
E. E. Fullerton ◽  
...  
Keyword(s):  
Time Scales ◽  
Magnetic Relaxation ◽  
Time Resolved ◽  
Subnanosecond Time

Using Space-Time Correlations to Identify Transient Defects

MRS Advances ◽  
2018 ◽  
Vol 3 (31) ◽  
pp. 1755-1760
Author(s):  
William Lowe ◽  
Jacob Eapen
Keyword(s):  
Dynamical Behavior ◽  
Atomistic Simulations ◽  
Dynamic Tension ◽  
Time Resolved ◽  
Scale Free ◽  
Self Organized ◽  
Time Correlations ◽  
Simulation Results ◽  
Early Radiation ◽  
Cubic Silicon Carbide

ABSTRACTAtomistic simulations are employed to investigate the dynamical behavior of atoms in cubic silicon carbide (SiC) following a 5 keV radiation knock. Specifically, we have computed the time-resolved van Hove self-correlation function, Gs(r,t), separately for the silicon and carbon sub-lattices. Our goal is to probe the early radiation damage mechanisms using a dynamical methodology. The simulation results show that the carbon atoms engage in a dynamic hopping mechanism as the system recovers from the radiation knock. The silicon atoms, however, exhibit a strikingly different behaviour: the time variation of 4πr2Gs(r,t) indicates a dynamic tension between the crystalline and disordered regions of the Si sub-lattice. The power-law tail of the 4πr2Gs(r,t) correlation for silicon atoms suggests a scale-free self-organized critical (SOC) state – a possible precursor to the collapse of the Si sub-lattice.

Onset of optical emission in femtosecond laser-induced plasmas and its correlation with surface dynamics monitored by pump–probe time-resolved microscopy

2019 ◽  
Vol 34 (10) ◽  
pp. 2119-2125 ◽  
Author(s):  
I. Carrasco-García ◽  
José M. Vadillo ◽  
J. Javier Laserna
Keyword(s):  
Femtosecond Laser ◽  
Time Scales ◽  
Emission Spectroscopy ◽  
Optical Emission Spectroscopy ◽  
Optical Emission ◽  
Surface Dynamics ◽  
Time Resolved ◽  
Pump Probe ◽  
Molecular Emission ◽  
Probe Microscope

Femtosecond time-resolved images acquired by using a two-color pump–probe microscope have been used in combination with optical emission spectroscopy to determine the time scales for the onset of atomic and molecular emission in laser-induced plasmas.

scholarly journals Optimizing a Time-Resolved Spectrometer for All Time Scales

2017 ◽  
Vol 112 (3) ◽  
pp. 453a
Author(s):  
Christian Litwinski ◽  
Sebastian Tannert ◽  
Manoel Veiga ◽  
Felix Koberling ◽  
Marcus Sackrow ◽  
...  
Keyword(s):  
Time Scales ◽  
Time Resolved
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