Material Grain Size Determines Relaxation-Time Distributions in Slow-Dynamics Experiments

2022 ◽  
Vol 17 (1) ◽  
Author(s):  
J. Kober ◽  
A.S. Gliozzi ◽  
M. Scalerandi ◽  
M. Tortello
Keyword(s):  
Grain Size ◽  
Relaxation Time ◽  
Slow Dynamics ◽  
Material Grain Size

Slow Dynamics Due to the Metal-Nonmetal Transition in Liquids

2003 ◽  
Vol 217 (7) ◽  
pp. 803-816 ◽  
Author(s):  
Makoto Yao ◽  
Hirotaka Kohno ◽  
Hiroaki Kajikawa
Keyword(s):  
Relaxation Time ◽  
Glass Transition ◽  
Liquid Glass ◽  
Sound Attenuation ◽  
Slow Dynamics ◽  
Anomalous Increase ◽  
Relaxation Strength ◽  
Transition Range ◽  
Liquid Dynamics ◽  
Nonmetal Transition

AbstractIt is well known that the liquid dynamics slows down on approaching the liquid-gas critical point or the liquid-glass transition. Recently we have found by the sound attenuation measurements that the metal-nonmetal (M-NM) transition also induces slow dynamics. In the M-NM transition range of expanded liquid Hg, we have observed anomalous increase in the sound attenuation due to the structural relaxation process. Assuming a simple Debye-type relaxation, we have estimated that the relaxation time should be of the order of nanoseconds and revealed that the relaxation strength has a broad maximum in the M-NM transition range. Moreover, two types of anomalies have been observed also in the semiconductor-metal (S-M) transition range of liquid Te-Se mixtures. We present the recent experimental results of the sound attenuation measurements and discuss briefly the mechanisms of the slow dynamics in the metal-nonmetal transition range of liquids.

A laboratory study of NMR relaxation times in unconsolidated heterogeneous sediments

Geophysics ◽  
2011 ◽  
Vol 76 (4) ◽  
pp. G73-G83 ◽  
Author(s):  
Elliot Grunewald ◽  
Rosemary Knight
Keyword(s):  
Grain Size ◽  
Relaxation Time ◽  
Time Distribution ◽  
Relaxation Times ◽  
Nmr Relaxation ◽  
Unconsolidated Sediments ◽  
Relaxation Response ◽  
Relaxation Time Distribution ◽  
Near Surface ◽  
Heterogeneous Sediments

Nuclear magnetic resonance (NMR) relaxation-time measurements can provide critical information about the physiochemical properties of water-saturated media and are used often to characterize geologic materials. In unconsolidated sediments, the link between measured relaxation times and pore-scale properties can be complicated when diffusing water molecules couple the relaxation response of heterogeneous regions within a well-connected pore space. Controlled laboratory experiments have allowed us to investigate what factors control the extent of diffusional coupling in unconsolidated sediments and what information is conveyed by the relaxation-time distribution under varied conditions. A range of sediment samples exhibiting heterogeneity in the form of a bimodal mineralogy of quartz and hematite were mixed with varied mineral concentration and grain size. NMR relaxation measurements and geometric analysis of these mixtures demonstrate the importance of two critical length scales controlling the relaxation response: the diffusion length ℓD, describing the distance a water molecule diffuses during the NMR measurement, and the separation length ℓS, describing the scale at which heterogeneity occurs. For the condition of ℓS > ℓD, which prevails for samples with low hematite concentrations and coarser grain size, coupling is weak and the bimodal relaxation-time distribution independently reflects the relaxation properties of the two mineral constituents in the heterogeneous mixtures. For the condition of ℓS < ℓD, which prevails at higher hematite concentrations and finer grain size, the relaxation-time distribution no longer reflects the presence of a bimodal mineralogy but instead conveys a more complex averaging of the heterogeneous relaxation environments. This study has shown the potential extent and influence of diffusional coupling in unconsolidated heterogeneous sediments, and can serve to inform the interpretation of NMR measurements in near-surface environments where unconsolidated sediments are commonly encountered.

Influence of the Plow Filling and Thread Angle onto the Plow Head Efficiency / Wpływ Współczynnika Wypełnienia Organu Oraz Kąta Nawinięcia Płata Ślimaka Na Sprawność Ładowania Frezującymi Organami Ślimakowymi

2015 ◽  
Vol 60 (1) ◽  
pp. 143-156 ◽  
Author(s):  
Tomasz Wydro
Keyword(s):  
Grain Size ◽  
Filling Rate ◽  
Optimal Loading ◽  
Loading Efficiency ◽  
Laboratory Examinations ◽  
Material Grain Size

Abstract Laboratory examinations on the plow heads at various filling rate and material grain-size, as well as various values of worm thread angle of the plow head have been executed. Influence of the worm thread angle and plow head filling onto optimal loading efficiency, has also been tested.

Enthalpy Relaxation Near the Glass Transition of a Supercooled Liquid [Ca(NO 3) 2]0.4[KNO3]0.6

1995 ◽  
Vol 407 ◽  
Author(s):  
I. K. Moon ◽  
Yoon-Hee Jeong
Keyword(s):  
Relaxation Time ◽  
Glass Transition ◽  
Specific Heat ◽  
Transition Region ◽  
Exponential Function ◽  
Supercooled Liquid ◽  
Frequency Range ◽  
Slow Dynamics ◽  
Glass Transition Region ◽  
Equilibrium Dynamics

ABSTRACTWe have investigated the slow dynamics in the glass transition region of a supercooled liquid [Ca(NO3)2]0.4[KN3]0.6 by measuring the dynamic specific heat in the frequency range from 0.01 Hz to 5 kHz. The equilibrium dynamics of the system in this range is well described by the stretched exponential function, exp[-(t/τ)β], and the Vogel-Fulcher type relaxation time, τ = τ0exp[Δ/(T − T0)].

Monitoring material grain size by laser‐generated ultrasound

1991 ◽  
Vol 59 (27) ◽  
pp. 3530-3532 ◽  
Author(s):  
A. Aharoni ◽  
M. Tur ◽  
K. M. Jassby
Keyword(s):  
Grain Size ◽  
Material Grain Size

scholarly journals Effect of Roughness on Discharge

2013 ◽  
Vol 4 (3) ◽  
pp. 29-33 ◽  
Author(s):  
T.W. Lau ◽  
N.R. Afshar
Keyword(s):  
Grain Size ◽  
Flow Rate ◽  
Roughness Coefficient ◽  
Coefficient Increase ◽  
Different Types ◽  
Channel Slope ◽  
Experimental Works ◽  
Bed Roughness ◽  
Material Grain Size ◽  
Effect Of Surface

These Water resource projects and hydraulic engineering works have been developing rapidly throughout the world, thus prediction of water roughness coefficient is becoming an importance criteria for the designs of hydraulic related structure like open channel, and dam structure. The purposes of this research are to determine the effect of roughness on discharge and study on the factors that affect roughness coefficient. The roughness coefficient for this study is expressed in terms of Manning’s n. Experimental works were carried out to study the effect of roughness by using flumes (8m x 0.3m x 0.4m) with different types of roughened bed such as 2mm grain size plate and 5mm grain size plate. The experiments were being tested with various flow rates for slope equal to 1:300, 1:600 and 1:900 to determine the effect of slope on roughness coefficient. The results of the experimental study were presented and shown that the effect of surface roughness, material grain size, channel slope, and Manning’s roughness coefficient on flow rate. For the range of conditions tested, the discharge was found to be decreased as roughness coefficient increase. From the experiments, it shows smoother surface is having lower roughness coefficient and less retarding effect on the water flow, higher flow rate is produced. As conclusion, flow rate and roughness coefficient were influenced by bed roughness and slope.

Elimination of membrane compliance in undrained triaxial testing. I. Measurement and evaluation

1993 ◽  
Vol 30 (5) ◽  
pp. 727-738 ◽  
Author(s):  
P.G. Nicholson ◽  
R.B. Seed ◽  
H.A. Anwar
Keyword(s):  
Grain Size ◽  
Test Results ◽  
Factors Affecting ◽  
Grain Sizes ◽  
Wide Range ◽  
Specimen Density ◽  
Thin Membranes ◽  
Alternative Approaches ◽  
Measurement And Evaluation ◽  
Material Grain Size

Several alternative approaches have been suggested for evaluation and correction of the testing errors caused by membrane compliance. The degree to which membrane compliance may affect the results of an undrained test is a function of the soil grain size and overall geometry of the test specimen, as well as specimen density and range of effective confining stresses during a given test. Membrane-compliance effects may be negligible for fine sands and silts tested in conventional 71 mm diameter samples, since even very thin membranes cannot penetrate significantly into the small surficial voids. For medium to coarse sands and gravels, however, membrane-compliance effects may have a significant influence on test results. The scope of this paper is threefold: firstly, to review, examine, and evaluate the variety of methods to measure and characterize membrane compliance; secondly, to develop an improved understanding of the factors affecting membrane compliance; and thirdly, to provide an enhanced, updated, and expanded correlation for estimating membrane compliance characteristics as a function of material grain size for a range of soil types, including a wide range of gradation types and representative grain sizes from silts through gravels. Key words : membrane, penetration, compliance, undrained testing, triaxial, measurement, evaluation.

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