Dynamic Scaling Research Articles

Signatures of nearly compensated magnetism and spin glass behavior in highly frustrated β-Mn-type Mn50Fe25+xAl25-x Heusler alloys.

The present study examines the effect of Fe/Al concentration on the structural and magnetic properties of Mn-rich Mn50Fe25+xAl25-x (x = 5, 10, 15) Heusler alloys through x-ray diffraction, temperature- and field-dependent DC magnetization, thermoremanent magnetization, magnetic memory effect, AC susceptibility measurements, and DFT calculations. The samples crystallize in a cubic β-Mn structure. The trend shows a reduction in lattice parameters (unit cell volume) with the increasing Fe proportion. These alloys exhibit strong antiferromagnetic interactions with large frustration parameters, indicating the presence of competing magnetic interactions. The DC magnetization data reveal spin glass-like features with a peak at spin glass freezing temperature (Tf). The observation of bifurcation in temperature-dependent zero-field-cooled and field-cooled magnetization curves, exponential dependence of the temperature variation of remanence and coercivity, magnetic relaxation, and magnetic memory effect below Tf support the spin-glass character of these alloys. The frequency dependence of Tf is also examined in the context of dynamic scaling laws, such as the Vogel-Fulcher law and critical slowing down model, which further supports the presence of spin glass behavior. In the theoretical DFT calculations, the electronic structure is found to be metallic and similar for both spin projections. Moreover, the antiferromagnetic arrangement of the magnetic moments, in line with the experimental observations, is stabilized by exchange interactions, resulting in an almost compensated total magnetic moment of 0.02-0.38µB/f.u. This is probably caused by the frustrated structure and non-stoichiometric compositions of Mn50Fe25+xAl25-x.

Dynamics of Water Clusters Confined in Ionic Liquid at an Elevated Pressure.

Over the years, numerous experimental and theoretical efforts have been dedicated to investigating the mysteries of water and determining its new unexplored physical properties. Despite this, high-pressure studies of water and aqueous mixtures close to the glass transition still represent an unknown area of research. Herein, we address a fundamental issue: the validity of the density scaling concept for fast water dynamics. For this purpose, we performed ambient and high-pressure dielectric measurements of a supercooled equimolar aqueous mixture of an acidic ionic liquid. All isothermal and isobaric relaxation data describing the time scale of charge transport (τσ) and fast dynamics within the water clusters (τν) reveal visual evidence of a liquid-glass transition. Furthermore, both relaxation processes satisfy the ργ/T scaling concept with a single exponent γ = 0.58. Thus, the scaling exponent is a state-point-independent parameter for the dynamics of water clusters confined in ionic liquid investigated in the pressure range up to 300 MPa.

Titanium Self-Intercalation Induced Formation of Orthogonal (1 × 1) Edge/Surface Reconstruction in 1T-TiSe2: Atomic Scale Dynamics and Mechanistic Study.

Edges and surfaces play indispensable roles in affecting the chemical-physical properties of materials, particularly in two-dimensional transition metal dichalcogenides (TMDCs) with reduced dimensionality. Herein, we report a novel edge/surface structure in multilayer 1T-TiSe2, i.e., the orthogonal (1 × 1) reconstruction, induced by the self-intercalation of Ti atoms into interlayer octahedral sites of the host TiSe2 at elevated temperature. Formation dynamics of the reconstructed edge/surface are captured at the atomic level by in situ scanning transmission electron microscopy (STEM) and further validated by density functional theory (DFT), which enables the proposal of the nucleation mechanism and two growth routes (zigzag and armchair). Via STEM-electron energy loss spectroscopy (STEM-EELS), a chemical shift of 0.6 eV in Ti L3,2 is observed in the reconstructed edge/surface, which is attributed to the change of the coordination number and lattice distortion. The present work provides insights to tailor the atomic/electronic structures and properties of 2D TMDC materials.

Energy Minimization Partial Task Offloading With Joint Dynamic Voltage Scaling and Transmission Power Control in Fog Computing

Energy Minimization Partial Task Offloading With Joint Dynamic Voltage Scaling and Transmission Power Control in Fog Computing

Selective harmonic elimination in PUC‐5 multilevel inverter using hybrid IGWO‐DE algorithm

AbstractThe use of a multilevel inverter has received significant attention in recent years due to its numerous advantages. Because of the widespread use of multilevel inverters in industries and applications that require a wide range of voltages, achieving high‐quality voltage has presented a number of challenges. Many studies have been carried out to address the problem of unwanted harmonics in multilevel inverters. The inverter switching can be done at a low frequency using the Selective Harmonic Elimination (SHE) technique, and the unwanted harmonics can be significantly reduced; however, the issue with SHE is solving the transcendental equations and determining the optimum switching angle. To address this problem, a new and improved hybrid algorithm is proposed that combines two evolutionary algorithms, gray wolf optimization (GWO) with an improved and new convergence factor and Differential evolution (DE) with a dynamic scaling factor using a crossover operator. In this paper, the optimum switching angles for a packed U cell 5‐level inverter are estimated using the proposed algorithm for distinct modulation index values, and simulation results are compared with different algorithms. The simulation result of the proposed algorithm, IGWO‐DE is confirmed through experiment.

Enhancing dragline operations supervision through computer vision: real time height measurement of dragline spoil piles dump using YOLO

Effective monitoring of spoil pile heights resulting from dragline dumps is critical in mining space management both safely and productively, particularly, during active overburden (OB) removal. This study addresses this concern by replicating stable dump piles in alignment with the dragline balancing diagrams at a dynamic scale, optimizing in-pit volume use. Real-time tracking of dump pile heights ensures efficient dump disposal management, garnering attention in the mining industry. Monitoring dump height and shape during OB disposal near the dragline is vital. It is proposed to employ an experimental setup, consistently dumping specific volume samples from predefined heights at constant velocities. The technique uses You Only Look Once (YOLO) for dump pile height measurements. A benchmark dataset is created, encompassing various dragline dump configurations. YOLO achieves an F1-confidence score of 84.6% and a mean average precision (mAP) value of 99.49% in accurately recognizing dump profiles. To validate its reliability, output is compared with photogrammetry (SFM-MVS and NeRF). Employing 2D computer vision (AI) on simulated video data offers a fast, cost-effective, real-time solution for secure dump pile profile detection and height measurement, enhancing dragline mining efficiency with stable and safe dump heights as per design.

Observation of Subdiffusive Dynamic Scaling in a Driven and Disordered Bose Gas.

We explore the dynamics of a tuneable box-trapped Bose gas under strong periodic forcing in the presence of weak disorder. In absence of interparticle interactions, the interplay of the drive and disorder results in an isotropic nonthermal momentum distribution that shows subdiffusive dynamic scaling, with sublinear energy growth and the universal scaling function captured well by a compressed exponential. We explain that this subdiffusion in momentum space can naturally be understood as a random walk in energy space. We also experimentally show that for increasing interaction strength, the gas behavior smoothly crosses over to wave turbulence characterized by a power-law momentum distribution, which opens new possibilities for systematic studies of the interplay of disorder and interactions in driven quantum systems.

High-fidelity correspondence imaging in complex media with varying thresholds and 1-bit compressive sensing

Here, we report high-fidelity correspondence imaging (CI) in complex media. By introducing varying thresholds to binarize single-pixel light intensities recorded in complex media, dynamic scaling factors can be eliminated. Then, the binarized light intensities and illumination patterns can be fed into a modified 1-bit compressive sensing algorithm to realize high-fidelity object reconstruction. The proposed method can implement object reconstruction with high fidelity in complex media without extra temporal carriers. It is experimentally verified that the method can effectively eliminate dynamic scaling factors and realize high-fidelity object reconstruction in complex media where conventional CI methods could fail. Experimental results demonstrate that the proposed method broadens a potential application of CI in complex media, e.g., turbid water, biological tissues, and dynamic smoke.

The dominating dimensionless numbers of an elastic-plastic thin plate under dynamic loading

The response of an elastic-plastic thin plate under dynamic loading cannot be solved theoretically since both geometrical and material nonlinearities are involved and also highly coupled. Obviously, the response will be affected by material properties, geometries, and loads, whose effects are usually studied separately. In order to avoid repeated investigations and save costs, identifying the combined dominant dimensionless number must be essential.For a plate under pressure loading, a dominating dimensionless number ξ (referred to as the loading intensity) is proposed based on energy conservation and dimensional analysis. As an input parameter, ξ whose physical meaning denotes the plastic to elastic share (energy ratio and deflection ratio), characterizes the combined effects of structure, material, and load. According to its value, responses could be classified into three cases: elastic deformation (0<ξ<1), elastic-plastic coupling deformation (1≤ξ≤100), and plastic dominating deformation (ξ>100). Furthermore, the dimensionless deflection of elastic-plastic plates could also be predicted, by combination of loading intensity ξ and relative stiffness β.In addition, for plates under other loading conditions, a series of dimensionless numbers are also given. Among them, some numbers have already been investigated by previous researchers, while others are still unconcerned. These numbers are then verified by FEM simulations, and their physical meanings are revealed. Employing these numbers, the analysis of experimental and simulation results will be in a normalized and comparable form. Particularly, it will provide scaling criteria for the dynamic scaling experiments.

Exploring music geography beyond the West: Clustering and mobility of Chinese musicians in the digital era

This study explores music geography beyond the Anglo-American circle through an investigation of the spatiality and mobility of musical workers in a Chinese context. Drawing on a dataset containing the information of 3,689 influential musicians in China’s music market, we investigated the (1) geographical landscape of China’s music industry, (2) spatial mobility of musicians at different stages of their careers, and (3) impact of digital technologies on the clustering of creative musical workers. Our study discovers a conspicuous clustering of post-work musicians in large metropolises, which reflects both the dynamics of scale and scope economies and the influence of state on the offering of cultural infrastructures and institutions in China. Most Chinese musicians have high trans-regional mobility and target locations (increasingly on the Chinese mainland) with large consumer markets or important art education institutions. The impact of geographical distance and agglomeration economies on musicians’ mobility varies at different stages of their careers. In addition, while digitalisation generates certain decentralising effects, enabling more musicians in formerly peripheral areas to enter the market and reducing the need for long-distance mobility, it also strengthens the advantages of dominant music clusters and produces precarious and volatile consequences in China’s music industry.

Heat release and flame scale effects on turbulence dynamics in confined premixed flows

As industry transitions to a net-zero carbon future, turbulent premixed combustion will remain an integral process for power generating gas turbines, aviation engines, and high-speed propulsion due to their ability to minimize pollutant emissions. However, accurately predicting the behavior of a turbulent reacting flow field remains a challenge. To better understand the dynamics of premixed reacting flows, this study experimentally investigates the effects of combustion heat release and flame scales on the evolution of turbulence in a high-speed, confined bluff-body combustor. The combustor is operated across a range of equivalence ratios from 0.7 to 1 to isolate the role of chemical heat release, flame speed, and flame thickness on the evolution of turbulence as the flow progresses from reactants to products. High-speed particle image velocimetry and CH* chemiluminescence imaging systems are simultaneously employed to quantify turbulent flame and flow dynamics. The results notably demonstrate that the flame augments turbulence fluctuations as the flow evolves from reactants to products for all cases, which opposes most simulations of premixed turbulent reactions. Notably, turbulence fluctuations increase monotonically with the heat of combustion and corresponding turbulent flame speed. Spatial profiles of turbulence statistics are conditioned on the mean flame front, and nondimensionalizing the turbulence profiles using laminar flame properties is shown to collapse all conditions onto a single curve. The resulting nondimensional profile confirms that turbulence dynamics scales with the heat of combustion and was used to develop a novel correlation to predict the increase in turbulent fluctuations across the premixed flame. A Reynolds averaged Navier Stokes decomposition is also explored to further characterize the effects of combustion heat release on the dominant mechanisms of turbulent energy transport. The cumulative results can guide modeling capabilities to better predict flame and flow dynamics and accelerate design strategies for premixed turbines with carbon-free fuels.

Dynamic Scaling Prediction Model and Application in Near-Wellbore Formation of Ultradeep Natural Gas Reservoirs

Summary To address the significant scaling challenges within the near-wellbore formation of ultradeep natural gas reservoirs characterized by high temperature and high salinity, we developed a dynamic scaling prediction model. This model is specifically designed for the prediction of scaling in gas-water two-phase seepage within fractured-matrix dual-porosity reservoirs. It accounts for the concentration effects resulting from the evaporation of water on formation water ions. Our scaling model is discretely solved using the finite volume method. We also conducted on-site dynamic scaling simulations for gas wells, allowing us to precisely predict the distribution of ion concentrations in the reservoir, as well as changes in porosity and permeability properties, and the scaling law dynamics. The simulation results reveal a significant drop in formation pressure, decreasing from 105 MPa to 76.7 MPa after 7.5 years of production. The near-wellbore formation is particularly affected by severe scaling, mainly attributed to the radial pressure drop funneling effect, leading to a reduction in scaling ion concentrations in the vicinity of the wellbore. Calcium carbonate is identified as the predominant scaling component within the reservoir, while calcium sulfate serves as a secondary contributor, together accounting for roughly 85.2% of the total scaling deposits. In contrast, the scaling impact on the matrix system within the reservoir remains minimal. However, the central fracture system exhibits notable damage, with reductions of 71.2% in porosity and 59.8% in permeability. The fracture system within a 5-m radius around the wellbore is recognized as the primary area of scaling damage in the reservoir. The use of the simulation approach proposed in this study can offer valuable support for analyzing the dynamic scaling patterns in gasfield reservoirs and optimizing scaling mitigation processes.

Chondrule formation during low‐speed collisions of planetesimals: A hybrid splash–flyby framework

AbstractChondrules probably formed during a small window of time ~1–4 Ma after CAIs, when most solid matter in the asteroid belt was already in the form of km‐sized planetesimals. They are unlikely, therefore, to be “building blocks” of planets or abundant on asteroids, but more likely to be a product of energetic events common in the asteroid belt at that epoch. Laboratory experiments indicate that they could have formed when solids of primitive composition were heated to temperatures of ~1600 K and then cooled for minutes to hours. A plausible heat source for this is magma, which is likely to have been abundant in the asteroid belt at that time, and only that time, due to the trapping of 26Al decay energy in planetesimal interiors. Here, we propose that chondrules formed during low‐speed () collisions between large planetesimals when heat from their interiors was released into a stream of primitive debris from their surfaces. Heating would have been essentially instantaneous and cooling would have been on the dynamical time scale, ~30 min, where is the mean density of a planetesimal. Many of the heated fragments would have remained gravitationally bound to the merged object and could have suffered additional heating events as they orbited and ultimately accreted to its surface. This is a hybrid of the splash and flyby models: We propose that it was the energy released from a body's molten interior, not its mass, that was responsible for chondrule formation by heating primitive debris that emerged from the collision.

Analysis of a test facility for transients in a supercritical water-cooled reactor using dynamic system scaling methodology

Depressurization in Supercritical Water-Cooled Reactors (SCWRs) presents challenges due to their unique operational conditions. Scaled-down facilities are preferred for analyzing depressurization phenomena due to the high costs associated with test facilities operating at 25 MPa. This study proposes the use of Dynamical System Scaling (DSS) methodology to analyze supercritical fluid depressurization processes and verify the similarity between the prototype and the model. A pressure vessel model is proposed, and fluid-to-fluid scaling indicates that carbon dioxide is the most suitable for similarity in this type of process. The analysis of depressurization compares a prototype that uses supercritical water with seven scaled models that use carbon dioxide as a model fluid. The similarity of these processes is assessed based on the temporal displacement rate. The results indicate error percentages below 4.5 %, validating the effectiveness of the proposed sizing method and highlighting the similarity of the depressurization processes over time.

A Foundation for Real-time Applications onFunction-as-a-Service

Serverless (or Function-as-a-Service) compute model enables new applications with dynamic scaling. However, all current Serverless systems are best-effort, and as we prove this means they cannot guarantee hard real-time deadlines, rendering them unsuitable for such real-time applications. We analyze a proposed extension of the Serverless model that adds a guaranteed invocation rate to the serverless model called Real-time Serverless. This approach aims to meet real-time deadlines with dynamically allocated function invocations. We first prove that the Serverless model does not support real-time guarantees. Next, we analyze Real-time Serverless, showing it can guarantee application real-time deadlines for rate-monotonic real-time workloads. Further, we derive bounds on the required invocation rate to meet any set of workload runtimes and periods. Subsequently, we explore an application technique, pre-invocation, and show that it can reduce the required guaranteed invocation rate. We derive bounds for the feasible rate guarantee reduction, and corresponding overhead in wasted compute resources. Finally, we apply the theoretical results to improve the experience quality of a distributed virtual reality/ augmented reality application as well as simplify the application design and resource management.

Progress in the Synthesis of Colloidal Machines.

For the past decade, the field of colloidal science has expanded the collection of colloidal particles to include an entire library of subunits that can be isotropic or anisotropic in terms of structural morphology or chemical composition. Using anisotropic subunits, the field has assembled a variety of static and dynamic structures. For this Account, we use the umbrella term "dynamic colloids" to describe subunits capable of movement, shape-shifting, or any other type of action in response to a stimulus and "static colloids" to describe those that are unresponsive to such stimuli. We view dynamic colloids as an access point to colloidal machines, a unique and emerging subfield of machines, and colloidal science. The assembly of dynamic subunits into colloidal machines differs from traditional self-assembly only in the final structures assembled, not the methods used. Dynamic assemblies have the capacity to interact with their environment in ways that traditional anisotropic self-assemblies do not. Here, we present the current state of the field of colloidal science toward the introduction of the next wave of colloidal machines. Machines are ubiquitous in nature and synthetic systems, governing every aspect of life. In mechanics, a machine is a device that transmits or modifies force or motion. In biology, nature's machines such as kinesin or ATP synthetase are essential to life. In the synthetic realm, molecular machines and nanomachines, recognized with the Nobel prize, include diverse systems, such as molecular rotors and elevators fabricated using bottom-up synthetic methods. On the microscale, microscopic motors based on microelectromechanical systems (MEMs) have been achieved via top-down methods such as micromachining. On the colloidal scale, machines are conspicuously absent due, in part, to the difficulty in navigating combinatory design spaces. We view colloidal machines (100 nm to 10 μm) as the next line of miniaturization in machines. Due to the bottom-up fabrication methods generally used in creating dynamic colloids, one can achieve complexity at a smaller scale than possible with top-down approaches. The introduction of colloidal scale machines would bridge the gap between the microscopic world with its macroscopic counterparts, the nanoworld with its molecular machines, and the biological world with nature's machinery. Reported colloidal machines to date are apparatuses that consist of multiple components of a single composition of dynamic subunits that come together to perform some work. The next step toward complex colloidal machines is systems containing multiple dynamic colloidal scale components that come together to act in tandem to perform some work on the surrounding environment. We envision repurposing a library of dynamic particles originally intended to be used as anisotropic subunits into dynamic components of a colloidal machine. Computationally, the idea of colloidal machines has been extensively explored; however, synthetically, there has been limited exploration. In order to implement this existing library into colloidal machines, the key next step is the development of synthetic combinatorial design spaces.

Dynamic Voltage and Frequency Scaling as a Method for Reducing Energy Consumption in Ultra-Low-Power Embedded Systems

Dynamic voltage and frequency scaling (DVFS) is a technique used to optimize energy consumption in ultra-low-power embedded systems. To ensure sufficient computational capacity, the system must scale up its performance settings. The objective is to conserve energy in times of reduced computational demand and/or when battery power is used. Fast Fourier Transform (FFT), Cyclic Redundancy Check 32 (CRC32), Secure Hash Algorithm 256 (SHA256), and Message-Digest Algorithm 5 (MD5) are focused functions that demand computational power to achieve energy-efficient performance. Selected operations are analyzed from the energy consumption perspective. In this manner, the energy required to perform a specific function is observed, thereby mitigating the influence of the instruction set or system architecture. For stable operating voltage scaling, an exponential model for voltage calculation is presented. Statistical significance tests are conducted to validate and support the findings. Results show that the proposed optimization technique reduces energy consumption for ultra-low-power applications from 27.74% to up to 47.74%.

Large magnetocaloric effect and exchange bias properties in Mn-Ni-Co-Sn full Heusler alloy

We have studied the structural, magnetic, magnetocaloric properties and exchange bias (EB) of a Mn-rich Mn-Ni-Co-Sn Heusler alloy, by means of the combined experimental and theoretical investigations. The alloy possesses tetragonal structure at room temperature (RT), and exhibits a first order martensitic transition at around 335 K. It also shows a large magnetocaloric effect in the vicinity of martensitic transition, with a maximum isothermal magnetic entropy change of around 35 J/kg.K, which is significantly larger than that reported for many other Heusler systems. Frequency dependence of spin freezing temperature obeying the dynamical scaling and Vogel-Fulcher law, along with the memory effect confirms the presence of cluster spin glass (CSG) state at low temperatures in the alloy. It shows EB effect at low temperatures, with a maximum EB field of 0.099 Tesla at 2 K, after field cooling in presence of 1 Tesla. Strong exchange coupling among the CSG clusters embedded in a strong ferrimagnetic matrix is found to be responsible for the observed EB. Ab-initio calculations using density functional theory on a representative Mn50Ni35.94Co6.25Sn7.81 alloy (very close to our experimental composition) shows the tetragonal structure with the ferrimagnetic ordering as the ground state, which is in good agreement with the experimental results. Exchange mechanism behind the observed EB in the present alloy has been discussed in the light of varying interatomic distances between different atomic pairs, and hence the magnetic coupling.

Study on scale formation and corrosion behavior of heat exchanger steel 20 at different temperatures

This study investigates the scaling and corrosion behavior of steel 20 of cooling water in two locations: oil depot working area and living quarters. Furthermore, it explores the effect of temperature on scaling rate and corrosion rate. Through static scaling test and dynamic scaling prediction, the scaling effect of water quality is analyzed. The results show that the scaling degree of two water quality conditions is different with the change of temperature. The water scaling initiates at 60 °C in the living quarters, while a slight amount of scaling occurs when the temperature reaches 75 °C at working area. Through the utilization of open circuit potential, polarization curve analysis, scanning electron microscope (SEM) imaging and X-ray diffraction, the corrosion potential, corrosion rate, macroscopic and microscopic corrosion samples, as well as corrosion products of steel 20 were comprehensively examined. It was found that, in the temperature range of 30 −50 °C, the corrosion rate of steel 20 in the working area showed a linear trend with water temperature, while the corrosion rate in the living quarters exhibited an exponential function trend with temperature. Considering the combined impact of scaling and corrosion on heat exchanger performance, if the operating conditions can exceed 40 °C, the water quality within the working area poses minimal risks and operational pressure to the heat exchanger. Therefore, it is more suitable as a cooling water source compared to that in living quarters.

Photomodulated phase-separation kinetics in block copolymer melts: a DPD simulation study

ABSTRACT We study phase-separation kinetics of symmetric diblock copolymer (BCP) melt in 3 d subjected to sequential light on/off cycles. The incompatible blocks of each BCP chain are connected by a photosensitive bond, which undergoes breakage during photo-illumination (on-cycle) and recombination during the off-cycle. We set a shorter fixed time limit for each on-cycles and focus on analysing how the much longer duration of the light off-cycles affects the segregation kinetics. We explore two scenarios for each off-cycle time variation: one with equal and another with increasing durations. For both cases, we determine the rate constants for bond formation and degradation reactions and assess their influence on the dynamical scaling functions and the growth scale of evolving morphologies. The average domain size typically exhibits diffusive growth ( R ( t ) ∼ t 1 / 3 ) for a couple of cycles in the beginning. However, the domain growth nearly freezes during the rest of the cycles, resulting in bicontinuous and nearly frozen isotropic morphologies.