Equivalent Time Temperature Model for Physical Aging and Temperature Effects on Polymer Creep and Relaxation

The equivalent time temperature method (ETT) is a novel extension of the equivalent time method. ETT is developed in this work to deal with time-temperature shifting of long-term polymer and polymer composite creep data, including the effects of physical aging at nonuniform temperature. Modifications to classical testing methods and protocols are presented to obtain accurate and repeatable data that can support long-term predictions with nonuniform temperature conditions through time. These techniques are used to generate momentary Time temperature superposition (TTSP) master curves, temperature shift factor rates, and aging shift factor rates. Novel interpretation and techniques are presented to deal with the coupled age-temperature behavior over long times. Validation of predictions against over 20,000 Hr of long-term data in field conditions is presented.

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Temperature Correction of Backcalculated Moduli and Deflections Using Linear Viscoelasticity and Time-Temperature Superposition

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1570-13 ◽

1997 ◽

Vol 1570 (1) ◽

pp. 108-117 ◽

Cited By ~ 6

Author(s):

Sun Woo Park ◽

Y. Richard Kim

Keyword(s):

Linear Viscoelasticity ◽

Superposition Principle ◽

Asphalt Mixture ◽

Temperature Shift ◽

Relaxation Modulus ◽

Analytical Description ◽

Shift Factor ◽

Temperature Correction ◽

Temperature Superposition ◽

Time Temperature Superposition

New analytical procedures for temperature correction of backcalculated asphalt concrete moduli and surface deflections were developed based on the theory of linear viscoelasticity and the time-temperature superposition principle and verified using falling weight deflectometer data and field temperature measurements. The new correction procedures explicitly utilize the thermorheological properties of the asphalt mixture. The resulting temperature-modulus correction factors depend only on the relaxation modulus and time-temperature shift factor of the mixture. The temperature-deflection correction factor depends on both the material properties and the layer thicknesses of the pavement section. Emphasis has been placed on the analytical description of the mixture’s thermoviscoelasticity responsible for temperature effects on mixture modulus and pavement deflection. A mechanistic framework for dealing with temperature correction problems for asphalt pavement has been introduced.

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Time–Temperature Superposition for Asphalt Mixtures with Growing Damage and Permanent Deformation in Compression

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1832-20 ◽

2003 ◽

Vol 1832 (1) ◽

pp. 161-172 ◽

Cited By ~ 27

Author(s):

Yanqing Zhao ◽

Y. Richard Kim

Keyword(s):

Permanent Deformation ◽

Superposition Principle ◽

Asphalt Mixture ◽

Temperature Shift ◽

Shift Factor ◽

Compression Tests ◽

Loading Test ◽

Temperature Superposition ◽

Time Temperature Superposition ◽

Time Temperature Superposition Principle

The objective in this study was to check the validity of the time–temperature superposition principle for hot-mix asphalt (HMA) with growing damage and viscoplastic strain in the compression state, which is essential for the permanent deformation characterization of HMA. Constant crosshead rate compression tests were conducted at temperatures between 25°C and 55°C, and data were analyzed to construct the stresslog reduced-time master curves for various strain levels. Research results indicate that HMA with growing damage remains thermorheologically simple in the temperature range used in this study and that the time–temperature shift factor is only a function of temperature and is independent of the strain level. Two types of tests, the repeated creep and recovery test and the cyclic sinusoidal loading test, were performed in this study to validate the time–temperature superposition in loading histories commonly used in asphalt mixture testing. The results further confirm that the time–temperature superposition is valid for HMA with growing damage and permanent deformation and that the response of HMA depends only on the reduced loading history.

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Rheological Characterization and Modeling of Thermally Unstable Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)

Polymers ◽

10.3390/polym13142294 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2294

Author(s):

Silvia Lajewski ◽

Annika Mauch ◽

Kalman Geiger ◽

Christian Bonten

Keyword(s):

Temperature Shift ◽

Processing Parameters ◽

Shift Factor ◽

Master Curves ◽

Plastic Pollution ◽

High Activation ◽

Rheological Characterization ◽

Rheological Measurement ◽

Frequency Sweeps ◽

High Temperature Sensitivity

Presently, almost every industry uses conventional plastics. Its production from petroleum and extensive plastic pollution cause environmental problems. More sustainable alternatives to plastics include bioplastics such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), which is produced by bacteria and is biodegradable even in seawater. High temperature sensitivity as well as massive thermal degradation cause difficulties during the processing of PHBV. The aim of this work is to create a detailed rheological characterization and master curves to gain deeper knowledge about the material and its processing parameters. The rheological characterization was performed with frequency sweeps in the range of 0.1 rad/s to 628 rad/s and time sweeps over 300 s. Creating master curves at the reference temperature of 180 °C with the software IRIS delivers Carreau and Arrhenius parameters. These parameters allow for a calculation of the master curves for all other temperatures by means of the temperature shift factor. Moreover, the rheological measurements reveal a minimum rheological measurement temperature of 178 °C and a surprisingly high activation energy of 241.8 kJ/mol.

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Hydrogeological responses in tropical mountainous springs

Memorias del I Congreso Internacional de Ciencias Exactas y Naturales ◽

10.15359/cicen.1.37 ◽

2019 ◽

Author(s):

Ricardo Sánchez-Murillo

Keyword(s):

Costa Rica ◽

Isotope Composition ◽

Central Valley ◽

Distribution Functions ◽

Geochemical Composition ◽

Transit Times ◽

Management Plans ◽

Best Fit ◽

Term Data

This study presents a hydrogeochemical analysis of spring responses (2013-2017) in the tropical mountainous region of the Central Valley of Costa Rica. The isotopic distribution of δ18O and δ2H in rainfall resulted in a highly significant meteoric water line: δ2H = 7.93×δ18O + 10.37 (r2=0.97). Rainfall isotope composition exhibited a strong dependent seasonality. The isotopic variation (δ18O) of two springs within the Barva aquifer was simulated using the FlowPC program to determine mean transit times (MTTs). Exponential-piston and dispersion distribution functions provided the best-fit to the observed isotopic composition at Flores and Sacramento springs, respectively. MTTs corresponded to 1.23±0.03 (Sacramento) and 1.42±0.04 (Flores) years. The greater MTT was represented by a homogeneous geochemical composition at Flores, whereas the smaller MTT at Sacramento is reflected in a more variable geochemical response. The results may be used to enhance modelling efforts in central Costa Rica, whereby scarcity of long-term data limits water resources management plans.

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Morphometric studies of artemia males from different populations of the Altai region

Rybovodstvo i rybnoe hozjajstvo (Fish Breeding and Fisheries) ◽

10.33920/sel-09-2007-03 ◽

2020 ◽

pp. 28-38

Author(s):

L. Vesnina ◽

G. Lukerina ◽

T. Ronzhina ◽

A. Savos’kin ◽

D. Surkov

Keyword(s):

Sexual Dimorphism ◽

Hydrogen Index ◽

Morphometric Parameters ◽

Altai Region ◽

Sexual Structure ◽

Different Populations ◽

Artemia Population ◽

Term Data ◽

Brine Salinity

The long-term data from morphometric studies of Artemia males from bisexual and parthenogenetic populations from hyperhaline reservoirs of the Altai region (Bolshoe Yarovoe Lake, Maloe Shklo Lake, and the Tanatar Lakes system) is analyzed in this paper. The description of signs of sexual dimorphism and sexual structure in different populations is given. The influence of brine salinity and hydrogen index on morphometric parameters of males was analyzed. There are differences in the sexual structure of the Artemia population: in the lakes Maloe Shklo and the thanatar system, the populations are bisexual (the share of males is 28.5 — 75.0 %), in the lake Bolshoe yarovoe — parthenogenetic (the share of males on average does not exceed 3 %). At the same time, sexual dimorphism is typical for both types of populations: females are larger than males, males have a larger head (the distance between the eyes is greater by 15.5 %, the diameter of the eye is 26.1 %, the length of the antenna is 22.3 %) and a larger number of bristles (36.1 %). The greatest variability is observed in the parameters of the Furka structure associated with the salinity of water by feedback and the pH — line indicator. Significant differences between the samples of males were revealed. The largest number of significant differences in morphometric indicators was found between samples of males from bisexual populations (lake thanatar and lake Maloe Shklo), the smallest — between males from the parthenogenetic population of lake Bolshoe yarovoe and males from lake Maloe Shklo.

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Information technology. Digitally recorded media for information interchange and storage. Test method for the estimation of lifetime of optical disks for long-term data storage

10.3403/30341531u ◽

2017 ◽

Keyword(s):

Information Technology ◽

Data Storage ◽

Test Method ◽

Storage Test ◽

Optical Disks ◽

Information Interchange ◽

And Storage ◽

Term Data

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Information technology. Digitally recorded media for information interchange and storage. Test method for the estimation of lifetime of optical disks for long-term data storage

10.3403/30341531 ◽

2017 ◽

Keyword(s):

Information Technology ◽

Data Storage ◽

Test Method ◽

Storage Test ◽

Optical Disks ◽

Information Interchange ◽

And Storage ◽

Term Data

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Diel, lunar and seasonal vertical migration in the deep western Gulf of Mexico evidenced from a long-term data series of acoustic backscatter

Progress In Oceanography ◽

10.1016/j.pocean.2021.102562 ◽

2021 ◽

pp. 102562

Author(s):

Laura Ursella ◽

Sara Pensieri ◽

Enric Pallàs-Sanz ◽

Sharon Z. Herzka ◽

Roberto Bozzano ◽

...

Keyword(s):

Gulf Of Mexico ◽

Vertical Migration ◽

Acoustic Backscatter ◽

Data Series ◽

Term Data

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Chances and challenges of a long-term data repository in multiple sclerosis: 20th birthday of the German MS registry

Scientific Reports ◽

10.1038/s41598-021-92722-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Lisa-Marie Ohle ◽

David Ellenberger ◽

Peter Flachenecker ◽

Tim Friede ◽

Judith Haas ◽

...

Keyword(s):

Multiple Sclerosis ◽

Sociodemographic Factors ◽

Healthcare Research ◽

Structure Design ◽

Data Repository ◽

Research Projects ◽

Real World Data ◽

Data Repositories ◽

Term Data

AbstractIn 2001, the German Multiple Sclerosis Society, facing lack of data, founded the German MS Registry (GMSR) as a long-term data repository for MS healthcare research. By the establishment of a network of participating neurological centres of different healthcare sectors across Germany, GMSR provides observational real-world data on long-term disease progression, sociodemographic factors, treatment and the healthcare status of people with MS. This paper aims to illustrate the framework of the GMSR. Structure, design and data quality processes as well as collaborations of the GMSR are presented. The registry’s dataset, status and results are discussed. As of 08 January 2021, 187 centres from different healthcare sectors participate in the GMSR. Following its infrastructure and dataset specification upgrades in 2014, more than 196,000 visits have been recorded relating to more than 33,000 persons with MS (PwMS). The GMSR enables monitoring of PwMS in Germany, supports scientific research projects, and collaborates with national and international MS data repositories and initiatives. With its recent pharmacovigilance extension, it aligns with EMA recommendations and helps to ensure early detection of therapy-related safety signals.

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