scholarly journals Long-Term Cathodoluminescent Characterization of Thin-Film Oxide Phosphors in a Wide Range of Electron Excitation Densities

2001 ◽  
Vol 667 ◽  
Author(s):  
Vyacheslav D. Bondar ◽  
Thomas E. Felter ◽  
Charles E. Hunt ◽  
Yuri G. Dubov ◽  
Andrei G. Chakhovskoi
Keyword(s):  
Thin Film ◽  
Electron Excitation ◽  
Beam Irradiation ◽  
Specific Behavior ◽  
Wide Range ◽  
Time Dependencies ◽  
Current Densities ◽  
Power Densities

ABSTRACTLong-term processes of cathodoluminescence degradation of thin film phosphors Zn2SiO4:Ti and Zn2GeO4:Mn were investigated in a wide range of e-beam energies, current and power densities. The time dependencies describing the decreasing of emission intensity have been found. At higher current densities of e-beam irradiation, the specific behavior of long-term degradation processes was observed, which is characterized by rapid initial degradation and a slower long term decrease. The most probable mechanisms are proposed for long-term processes of degradation in the investigated phosphors.

scholarly journals Creep Behavior of Passive Bovine Extraocular Muscle

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Lawrence Yoo ◽  
Hansang Kim ◽  
Andrew Shin ◽  
Vijay Gupta ◽  
Joseph L. Demer
Keyword(s):  
Relaxation Function ◽  
Loading Rate ◽  
Creep Function ◽  
Testing Conditions ◽  
Loading Rates ◽  
Creep Coefficient ◽  
Wide Range ◽  
The Mean

This paper characterized bovine extraocular muscles (EOMs) using creep, which represents long-term stretching induced by a constant force. After preliminary optimization of testing conditions, 20 fresh EOM samples were subjected to four different loading rates of 1.67, 3.33, 8.33, and 16.67%/s, after which creep was observed for 1,500 s. A published quasilinear viscoelastic (QLV) relaxation function was transformed to a creep function that was compared with data. Repeatable creep was observed for each loading rate and was similar among all six anatomical EOMs. The mean creep coefficient after 1,500 seconds for a wide range of initial loading rates was at1.37±0.03(standard deviation, SD). The creep function derived from the relaxation-based QLV model agreed with observed creep to within 2.7% following 16.67%/s ramp loading. Measured creep agrees closely with a derived QLV model of EOM relaxation, validating a previous QLV model for characterization of EOM biomechanics.

Holistic Characterization of Carbon Nanotube Membrane for Capacitive Deionization Electrodes Application

2015 ◽  
Vol 1752 ◽  
pp. 125-130 ◽  
Author(s):  
Yamila M. Omar ◽  
Carlo Maragliano ◽  
Chia-Yun Lai ◽  
Francesco Lo Iacono ◽  
Nicolas Bologna ◽  
...  
Keyword(s):  
Thin Film ◽  
Material Characterization ◽  
Capacitive Deionization ◽  
Carbon Nanostructure ◽  
Rate Dependent ◽  
Wide Range ◽  
Materials Used ◽  
Multiwall Carbon ◽  
Mechanical Surface

ABSTRACTOne of the main areas of improvement in capacitive deionization technologies is the materials used for electrodes which have very specific requirements. In the present work, a wide range of material characterization techniques are employed to determine the suitability of a multiwall carbon nanostructure thin film as electrode material. The electrical, mechanical, surface and wetting characteristics are studied proving the membrane highly conductive (σ=7.25 103 S/m), having competitive electro-sorption capacity (11.7 F/g at 10 mV/s) and surface area (149 m2/g), strain rate dependent mechanical properties and hydrophobic wetting behavior.

Current Chemistry: Characterization of Thin-Film Surfaces and Interfaces Using Neutron Reflectometry

2001 ◽  
Vol 54 (8) ◽  
pp. 487 ◽  
Author(s):  
Michael James
Keyword(s):  
Thin Film ◽  
Data Analysis ◽  
Experimental Design ◽  
Extreme Environments ◽  
Neutron Reflectometry ◽  
Buried Interfaces ◽  
Surfaces And Interfaces ◽  
Wide Range ◽  
Non Destructive

Neutron reflectometry has become an increasingly important technique in the characterization of thin-film surfaces and interfaces. Recent advances in instrumentation, experimental design, sample environments and methods of data analysis now make it possible to obtain an angstrom-precision depth profile of the film composition. Neutrons are non-destructive and highly penetrating which makes them ideal probes for the study of buried interfaces as well as surfaces under a wide range of extreme environments. Isotopic H/D substitution (particularly in colloidal, polymeric or biological systems) provides a unique tool for selectively labelling different components of complex planar architectures. The fundamental aspects of neutron reflectometry are discussed, and the utility of this technique is illustrated by a review of several recent studies.

Correlating Laboratory Conditioning with Field Aging for Asphalt using Rheological Parameters

2020 ◽  
Vol 2674 (5) ◽  
pp. 393-404 ◽  
Author(s):  
Runhua Zhang ◽  
Jo E. Sias ◽  
Eshan V. Dave
Keyword(s):  
Asphalt Binder ◽  
Life Time ◽  
Rheological Parameters ◽  
Performance Grade ◽  
Wide Range ◽  
Binder Aging ◽  
Long Term Performance ◽  
Term Performance

Aging has a significant effect on performance of asphalt materials. Reliable characterization of asphalt binder properties with aging is crucial to improving asphalt binder specifications as well as modification and formulation methods. The objective of this study is to correlate the laboratory conditioning methods with field aging using evolution of binder rheological parameters with time and pavement depth. Loose mixtures are aged in the lab (5 and 12 days aging at 95°C, and 24 h at 135°C) and recovered binder rheological properties are compared with those from different layers of field cores. The virgin binder results with 20 h pressure aging vessel (PAV) aging are also included. Binder testing is conducted using a dynamic shear rheometer with a 4 mm plate over a wide range of frequencies and temperatures. Rheological parameters calculated from the master curves, performance grade system, and binder Christensen–Anderson–Marasteanu model are used to evaluate changes with aging. The field aging gradient is evaluated, and the laboratory conditioning durations corresponding with the field aging durations at different pavement depths are calculated. The results show that 5 days of aging can simulate around 8 years of field aging (in New Hampshire) for the top 12.5 mm pavement, and 12 days’ aging can simulate approximately 20 years; 20 h PAV binder aging is not adequate to capture the long-term performance of the pavement. This study provides a way to optimize the laboratory conditioning durations and evaluate the performance of asphalt material with respect to pavement life (time) and depth (location) within the pavement structure.

Large-sample hydrology to foster open and collaborative research: a review of recent progress and grand challenges

2020 ◽  
Author(s):  
Gemma Coxon ◽  
Nans Addor ◽  
Camila Alvarez-Garreton ◽  
Hong X. Do ◽  
Keirnan Fowler ◽  
...  
Keyword(s):  
Human Impacts ◽  
Individual Case ◽  
Large Sample ◽  
Large Sets ◽  
Uncertainty Estimates ◽  
Wide Range ◽  
Diverse Data

<p>Large-sample hydrology (LSH) relies on data from large sets (tens to thousands) of catchments to go beyond individual case studies and derive robust conclusions on hydrological processes and models and provide the foundation for improved understanding of the link between catchment characteristics, climate and hydrological responses. Numerous LSH datasets have recently been released, covering a wide range of regions and relying on increasingly diverse data sources to characterize catchment behaviour. These datasets offer novel opportunities for open hydrology, yet they are also limited by their lack of comparability, accessibility, uncertainty estimates and characterization of human impacts.</p><p>Here, we underscore the key role of LSH datasets in open hydrologic science and highlight their potential to enhance the transparency and reproducibility of hydrological studies.  We provide a review of current LSH datasets and identify their limitations, including the current difficulties of inter-dataset comparison and limited accessibility of hydrological observations. To overcome these limitations, we propose simple guidelines alongside long-term coordinated actions for the community, which aim to standardize and automatize the creation of LSH datasets worldwide. This presentation will highlight how, by producing and using common LSH datasets, the community can increase the comparability and reproducibility of hydrological research.</p><p>This research was performed as part of the Panta Rhei Working Group on large-sample hydrology and is based on https://doi.org/10.1080/02626667.2019.1683182.</p>

scholarly journals Characterization of high-precision resistive voltage divider and buffer amplifier for ac voltage metrology

2019 ◽  
Vol 10 ◽  
pp. 8
Author(s):  
Bjørnar Karlsen ◽  
Kåre Lind ◽  
Helge Malmbekk ◽  
Per Ohlckers
Keyword(s):  
High Precision ◽  
Electrical Power ◽  
Voltage Divider ◽  
Long Term Stability ◽  
Wide Range ◽  
Precision Voltage ◽  
Best Fit ◽  
Better Than

A high-precision voltage buffer and a 10:1 resistive voltage divider have been constructed for use in ac voltage and electrical power metrology. Long-term stability of the buffer's dc response has been demonstrated by two dc sweeps performed 20 days apart, with best-fit linearized gain varying less than 1 μV/V. The absolute ac gain has been measured using a high-precision digital multimeter for 10 Hz and 1 kHz with results consistent with dc within 5 μV/V. This value agrees with the characterization of ac–dc difference using thermal converters from different producers with a variety of resistance for various voltages from 1 V to 5 V. The ac–dc difference was further characterized better than 40 μV/V for the same voltages up to 100 kHz and better than 100 μV/V for 3 V at 1 MHz. Absolute ac gain and ac–dc difference has also been measured for the voltage divider and buffer combination from 10 V to 50 V, with similar agreement up to 1 kHz. The ac–dc difference from 10 Hz to 100 kHz of this combination shows an agreement well within 30 μV/V in this entire voltage span with a total response not exceeding 125 μV/V. This make the voltage divider and buffer combination suitable for sampling electrical powers for a wide range of voltages.

scholarly journals Negative Piezoresistive Effect in a Stretchable Device Based on a Soft Tunneling Barrier

2020 ◽  
Author(s):  
Soosang Chae ◽  
Ivan Fotev ◽  
Eva Bittrich ◽  
Won Jin Choi ◽  
Petra Uhlmann ◽  
...  
Keyword(s):  
Thin Film ◽  
Electron Tunneling ◽  
Essential Feature ◽  
Metal Electrode ◽  
Strain Sensing ◽  
Poisson Effect ◽  
Wide Range ◽  
Standby Power ◽  
Swelling Volume

Abstract Piezoresistive soft composite materials are widely used in strain sensing and typically exhibit a decrease in conductivity upon elongation—the so-called positive gauge effect. We demonstrate a thin-film architecture that features the inverse behavior: a strain-induced transition from insulating to metallic conductivity, spanning nine orders of magnitude in conductivity. Our approach is based on a nanometer-scale sandwiched bilayer Au thin film with a polydimethylsiloxane elastomeric barrier layer. Upon application of strain, the thickness of the thin soft barrier decreases because of the strain governed by the Poisson effect, followed by electron-tunneling currents through the barrier, forming an interconnected bilayer metal electrode. An extremely high on–off electrical conductivity ratio (~ 109) is observed over a wide range of working strains (as high as 130%), which mimics the ideal features of a mechanical-force-controlled electric transistor. This conceptual design strategy is expected to benefit a wide range of applications in which operation under minimal standby power could be an essential feature, such as in implantable soft strain sensors and in prosthetic long-term monitoring systems for detecting sudden a swelling/volume expansion of human body organs or blood vessels, thereby helping to avoid acute and severe syndromes.

Surface characterization of thin film induced by He+ ion-beam irradiation into PLLA

2005 ◽  
Vol 196 (1-3) ◽  
pp. 383-388 ◽  
Author(s):  
Tasuku Yotoriyama ◽  
Yoshiaki Suzuki ◽  
Takaya Mise ◽  
Takeyo Tsukamoto ◽  
Masaya Iwaki
Keyword(s):  
Thin Film ◽  
Surface Characterization ◽  
Ion Beam ◽  
Beam Irradiation ◽  
Ion Beam Irradiation

Impact of Various Trucks on Pavement Design and Analysis

2013 ◽  
Vol 2339 (1) ◽  
pp. 120-127
Author(s):  
Olga Selezneva ◽  
Aditya Ramachandran ◽  
Endri Mustafa ◽  
Regis Carvalho
Keyword(s):  
Pavement Design ◽  
Loading Conditions ◽  
Vehicle Class ◽  
Load Spectra ◽  
Heavy Trucks ◽  
Weigh In Motion ◽  
Wide Range ◽  
Design Guide

This investigation assessed the sensitivity of Mechanistic–Empirical Pavement Design Guide (MEPDG) outcomes to normalized axle load spectra representing various loading conditions observed in the Specific Pavement Studies Transportation Pooled Fund Study of the Long-Term Pavement Performance program. The goal was to determine what vehicle classes and axle types with a wide range of axle loading conditions are likely to cause differences in pavement design outcomes when the MEPDG is used. Significant differences found in the MEPDG outcomes support the need for characterization of axle loading beyond a single default value for heavy trucks that dominate vehicle class distributions, especially for Class 9 trucks. The absence of differences for lightweight and under-represented trucks indicates that load spectra from various sites could be combined to develop a single default for some vehicle classes and axle types. The effect of bias in weigh-in-motion (WIM) axle weight measurements on the normalized axle load spectra estimates and the associated MEPDG outcomes was also investigated. It was found that drift in WIM system calibration leading to a more than 5% bias in mean error between true and WIM-measured axle weight could lead to significant differences in MEPDG design outcomes. These results were used to develop recommendations for creating axle loading defaults for the MEPDG.

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