A5035206469- Theoretical and Computational Physics
- Metallic Glasses and Amorphous Alloys
- Material Dynamics and Properties
- earthquake and tectonic studies
- Magnetic Properties and Applications
- High Entropy Alloys Studies
- Earthquake Detection and Analysis
- Physics of Superconductivity and Magnetism
- High-pressure geophysics and materials
- High-Temperature Coating Behaviors
- Complex Systems and Time Series Analysis
- Landslides and related hazards
- Magnetic properties of thin films
- Granular flow and fluidized beds
- Stochastic processes and statistical mechanics
- Force Microscopy Techniques and Applications
- Advanced Condensed Matter Physics
- Advanced Thermodynamics and Statistical Mechanics
- Microstructure and mechanical properties
- Seismology and Earthquake Studies
- Geomagnetism and Paleomagnetism Studies
- Nonlinear Dynamics and Pattern Formation
- Quantum many-body systems
- stochastic dynamics and bifurcation
- Geotechnical and Geomechanical Engineering
University of Illinois Urbana-Champaign
2016-2025
University of Illinois System
2014-2019
Center for Genomic Science
2005-2018
University of Tennessee at Knoxville
2017
B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine
2017
National Academy of Sciences of Ukraine
2017
University of Hong Kong
2017
Institute of Mechanics
2017
Zhengzhou University
2017
University of Southern California
2009
We use the zero-temperature random-field Ising model to study hysteretic behavior at first-order phase transitions. Sweeping external field through zero, exhibits hysteresis, return-point memory effect, and avalanche fluctuations. There is a critical value of disorder which jump in magnetization (corresponding an infinite avalanche) first occurs. universal this point using mean-field theory, also present results numerical simulations three dimensions.
The tasks of neural computation are remarkably diverse. To function optimally, neuronal networks have been hypothesized to operate near a nonequilibrium critical point. However, experimental evidence for dynamics has inconclusive. Here, we show that the cultured cortical critical. We analyze network data collected at individual neuron level using framework phase transitions. Among most striking predictions confirmed is mean temporal profiles avalanches widely varying durations quantitatively...
A basic micromechanical model for deformation of solids with only one tuning parameter (weakening $\ensuremath{\epsilon}$) is introduced. The can reproduce observed stress-strain curves, acoustic emissions and related power spectra, event statistics, geometrical properties slip, a continuous phase transition from brittle to ductile behavior. Exact universal predictions are extracted using mean field theory renormalization group tools. results agree recent experimental observations...
For the first time in metallic glasses, we extract both exponents and scaling functions that describe nature, statistics, dynamics of slip events during slow deformation, according to a simple mean field model. We model slips as avalanches rearrangements atoms coupled shear transformation zones (STZs). Using high temporal resolution measurements, find predicted, different statistics for small large thereby excluding self-organized criticality. The agreement between data across numerous...
Recent experimental and theoretical progress on the study of crackling noise in plastic deformation crystals, ferroelastics, porous materials is reviewed. We specifically point out opportunities potential pitfalls this approach to nonequilibrium dynamics disordered materials. Direct optical observation domain boundary movement under stress results from acoustic emission heat-flux measurements lead power-law scaling jerk distribution with energy exponents between 1.3 2.3. The collapse leads...
We explain Barkhausen noise in magnetic systems terms of avalanches domains near a plain old critical point the hysteretic zero-temperature random-field Ising model. The avalanche size distribution has universal scaling function, making nontrivial predictions shape up to 50% above point, where two decades are still observed. simulate with ${1000}^{3}$ domains, extract exponents 2, 3, 4, and 5 dimensions, compare our 2D $6\ensuremath{-}\ensuremath{\epsilon}$ predictions, variety experiments.
Simple models for ruptures along a heterogeneous earthquake fault zone are studied, focusing on the interplay between roles of disorder and dynamical effects. A class found to operate naturally at critical point whose properties yield power-law scaling statistics. Various effects can change behavior distribution small events combined with characteristic system size events. The studies employ various analytic methods as well simulations.
Hysteresis loops are often seen in experiments at first-order phase transformations, when the system goes out of equilibrium. They may have a macroscopic jump (roughly as supercooling liquids) or they be smoothly varying (as most magnets). We studied nonequilibrium zero-temperature random-field Ising-model model for hysteretic behavior transformations. As disorder is added, one finds transition where magnetization (corresponding to an infinite avalanche) decreases zero. At this we find...
We present numerical simulations of avalanches and critical phenomena associated with hysteresis loops, modeled using the zero-temperature random-field Ising model. study transition between smooth loops a sharp jump in magnetization, as disorder our model is decreased. In large region near point, we find scaling phenomena, which are well described by results an $\ensuremath{\epsilon}$ expansion about six dimensions. three, four, five dimensions, systems up to billion spins ${(1000}^{3}).$
We show that slowly sheared metallic nanocrystals deform via discrete strain bursts (slips), whose size distributions follow power laws with stress-dependent cutoffs. for the first time plasticity reflects tuned criticality, by collapsing slip-size onto a predicted scaling function. Both power-law exponents and function agree mean-field theory predictions. Our study of 7 materials 2 crystal structures, at various deformation rates, stresses, sizes down to 75 nm, attests universal...
A series of high entropy alloys (HEAs), AlxNbTiMoV, was produced by a vacuum arc-melting method. Their microstructures and compressive mechanical behavior at room temperature were investigated. It has been found that single solid-solution phase with body-centered cubic (BCC) crystal structure forms in these alloys. Among alloys, Al0.5NbTiMoV reaches the highest yield strength (1,625 MPa), which should be attributed to considerable strengthening behavior. Furthermore, serration crackling...
Ingots of the bulk metallic glass (BMG), Zr64.13Cu15.75Ni10.12Al10 in atomic percent (at. %), are compressed at slow strain rates. The deformation behavior is characterized by discrete, jerky stress-drop bursts (serrations). Here we present a quantitative theory for serration BMGs, which critical issue understanding characteristics BMGs. mean-field interaction model predicts scaling distribution, D(S), avalanche sizes, S, experiments. D(S) follows power law multiplied an...
Abstract The physical processes governing the onset of yield, where a material changes its shape permanently under external deformation, are not yet understood for amorphous solids that intrinsically disordered. Here, using molecular dynamics simulations and mean-field theory, we show at critical strain amplitude sizes clusters atoms undergoing cooperative rearrangements displacements (avalanches) diverges. We compare this non-equilibrium behaviour to prevailing concept ‘front depinning’...
Abstract High-entropy alloys (HEAs) are new that contain five or more elements in roughly-equal proportion. We present experiments and theory on the deformation behavior of HEAs under slow stretching (straining) observe differences, compared to conventional with fewer elements. For a specific range temperatures strain-rates, deform jerky way, sudden slips make it difficult precisely control deformation. An analytic model explains these as avalanches slipping weak spots predicts observed slip...
Abstract The search for scale-bridging relations in the deformation of amorphous materials presents a current challenge with tremendous applications material science, engineering and geology. While generic features flow microscopic dynamics support idea universal scaling theory deformation, direct evidence remains poor. Here, we provide first measurement internal granular matter. By combining macroscopic force fluctuation measurements strain imaging, demonstrate existence robust from...
Abstract Slowly-compressed single crystals, bulk metallic glasses (BMGs), rocks, granular materials and the earth all deform via intermittent slips or “quakes”. We find that although these systems span 12 decades in length scale, they show same scaling behavior for their slip size distributions other statistical properties. Remarkably, follow power law multiplied with exponential cutoff. The cutoff grows applied force spanning scales from nanometers to kilometers. tuneability of stress...
Abstract Refractory high-entropy alloys present attractive mechanical properties, i.e., high yield strength and fracture toughness, making them potential candidates for structural applications. Understandings of atomic electronic interactions are important to reveal the origins formation their structure−dominated thus enabling development a predictive approach rapidly designing advanced materials. Here, we report basis valence−electron-concentration-categorized principles observed serration...