scholarly journals Notable Enhancement of Phase Transition Performance and Luminous Transmittance in VO2 Films via Simple Method of Ar/O Plasma Post-Treatment

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 102 ◽  
Author(s):  
Jingcheng Jin ◽  
Dongping Zhang ◽  
Xiaonan Qin ◽  
Yu Yang ◽  
Ying Huang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Amplitude ◽  
Interfacial Area ◽  
Post Treatment ◽  
Simple Method ◽  
Plasma Irradiation ◽  
Boundary State ◽  
Surface Migration ◽  
Interfacial Boundary ◽  
Better Than

Ar/O plasma irradiation is proposed for post-treatment of vanadium dioxide (VO2) films. Oxidation and surface migration were observed in the VO2 films following irradiation. This combined effect leads to an effective stoichiometry refinement and microstructure reconstruction in the interfacial area. A notable improvement in luminous transmittance and an enhancement in phase transition performance of the treated VO2 films were achieved. Compared with that of as-deposited VO2 films, the electrical phase transition amplitude of treated films increased more than two-fold. The relative improvement in luminous transmittance (380–780 nm) is 47.4% (from 25.1% to 37%) and the increase in solar transmittance is 66.9% (from 29.9% to 49.9%), which is comparable to or better than the previous work using anti-reflection (AR) coatings or doping methods. The interfacial boundary state proved to be crucial and Ar/O plasma irradiation offers an effective approach for further refinement of thermochromic VO2 films.

scholarly journals Fish bone-derived interconnected carbon nanofibers for efficient and lightweight microwave absorption

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Yangyang Gu ◽  
Peng Dai ◽  
Wen Zhang ◽  
Zhanwen Su
Keyword(s):  
Microwave Absorption ◽  
Carbon Nanofibers ◽  
Three Dimensional ◽  
Fish Bone ◽  
Absorption Properties ◽  
Simple Method ◽  
Microwave Absorption Properties ◽  
Absorption Performance ◽  
Microwave Absorption Performance ◽  
Better Than

AbstractIn this work, we demonstrated a simple method for preparing three-dimensional interconnected carbon nanofibers (ICNF) derived from fish bone as an efficient and lightweight microwave absorber. The as-obtained ICNF exhibits excellent microwave absorption performance with a maximum reflection loss of –59.2 dB at the filler content of 15 wt%. In addition, the effective absorption bandwidth can reach 4.96 GHz at the thickness of 2 mm. The outstanding microwave absorption properties can be mainly ascribed to its well-defined interconnected nanofibers architecture and the doping of nitrogen atoms, which are also better than most of the reported carbon-based absorbents. This work paves an attractive way for the design and fabrication of highly efficient and lightweight electromagnetic wave absorbers.

scholarly journals Simple Method for Estimating the Contribution of Neighbouring n-beam Interactions to Two-beam Structure Factors

1988 ◽  
Vol 41 (3) ◽  
pp. 469
Author(s):  
HJ Juretschke ◽  
HK Wagenfeld
Keyword(s):  
Experimental Determination ◽  
Structure Factor ◽  
Beam Structure ◽  
Simple Method ◽  
Experimental Configuration ◽  
Structure Factors ◽  
Special Cases ◽  
Better Than

Unless special precautions are taken, the experimental determination of two-beam structure factors to better than 1 % may include contributions from neighbouring n-beam interactions. In any particular experimental configuration, corrections for such contributions are easily carried out using the modified two-beam structure factor formalism developed recently (Juretschke 1984), once the full indexing of the pertinent n-beam interactions is known. The method is illustrated for both weak and strong primary reflections and its applicability in special cases, as well as for less than perfect crystals, is discussed.

Numerical Simulation of Boiling Flows Using an Eulerian Multi-Fluid Model

2005 ◽  
Author(s):  
J. Han ◽  
D.-M. Wang ◽  
D. Filipi
Keyword(s):  
Mathematical Model ◽  
Fluid Model ◽  
Bubble Diameter ◽  
Interfacial Area ◽  
Nucleate Boiling ◽  
Industrial Applications ◽  
Turbulent Dispersion ◽  
Steady State Mode ◽  
Simple Method ◽  
Bubble Number

A mathematical model to simulate boiling flows in industrial applications is presented. Following the Eulerian multifluid framework, separate sets of mass, momentum, and energy conservation equations are solved for liquid and vapor phases, respectively. The interactions between the phases are accounted for by including relevant mass, momentum, heat exchanges and turbulent dispersion effects. Velocity-pressure coupling is achieved through a multiphase version of the SIMPLE method and the standard k-ε turbulence model is employed. In order to validate and assess the accuracy of the boiling model, subcooled nucleate boiling flows in a vertical annular pipe are simulated in the steady-state mode. The computed axial velocities, volume fractions, temperature profiles are compared with available experimental data (Roy et al., ASME J. of Heat Transfer, Vol. 119, 1997). The result obtained by assuming a constant value for the bubble diameter shows a reasonable agreement, but several limitations are observed in the details. A more advanced mathematical model incorporating separate transport equations for the bubble number density and the interfacial area is suggested.

Thermochromic VO2 Thin Film Prepared by Post Annealing Treatment of V2O5 Thin Film

2009 ◽  
Vol 79-82 ◽  
pp. 747-750 ◽  
Author(s):  
Dong Qing Liu ◽  
Wen Wei Zheng ◽  
Hai Feng Cheng ◽  
Hai Tao Liu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transition ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Annealing Treatment ◽  
Simple Method ◽  
X Ray ◽  
Post Annealing ◽  
Vo2 Thin Films

Thermochromic vanadium dioxide (VO2) exhibits a semi-conducting to metallic phase transition at about 68°C, involving strong variations in electrical and optical properties. A simple method was proposed to prepare VO2 thin films from easily gained V2O5 thin films. The detailed thermodynamic calculation was done and the results show that V2O5 will decompose to VO2 when the post annealing temperature reaches 550°C at the atmospheric pressure of less than 0.06Pa. The initial V2O5 films were prepared by sol-gel method on fused-quartz substrates. Different post annealing conditions were studied. The derived VO2 thin film samples were characterized using X-ray diffraction and X-ray photoelectron spectroscopy. The electrical resistance and infrared emissivity of VO2 thin films under different temperatures were measured. The results show that the VO2 thin film derived from the V2O5 thin film annealed at 550°C for 10 hours is pure dioxide of vanadium without other valences. It was observed that the resistance of VO2 thin film with thickness about 600nm can change by 4 orders of magnitude and the 7.5-14μm emissivity can change by 0.6 during the phase transition.

THE SORPTION OF VAPORS BY ACTIVE SILICA

1935 ◽  
Vol 12 (1) ◽  
pp. 41-56 ◽  
Author(s):  
L. M. Pidgeon
Keyword(s):  
Water Vapor ◽  
Silica Gel ◽  
Dynamic Method ◽  
Activated Alumina ◽  
Simple Method ◽  
Commercial Alumina ◽  
Method Of Production ◽  
Effective Sorbent ◽  
Better Than

The sorptive properties of a new active silica have been examined. This sorbent is prepared by the action of acids on the mineral serpentine. The quartz spiral sorption balance has been employed to obtain isotherms for water, benzene and alcohol. Relative rates of sorption have been measured and compared with those for silica gel.Efficiency measurements have also been made, using the dynamic method, with water vapor as the sorbate. Comparative measurements have been carried out on commercial silica gel, and data are cited from the literature for activated alumina. A comparison of the data indicates that active silica is inferior to silica gel but somewhat better than commercial alumina. Its simple method of production combined with reasonably good sorptive properties should result in a cheap and effective sorbent for technical purposes.The type of isotherm exhibited by active silica is similar to that associated with the "chalky" gels described by Holmes. Certain theoretical aspects of sorption by "chalky" and "vitreous" gels are discussed.

Turbulent Heat Transfer in a Backward-Facing Step Flow Using a Non-Linear k-ε Model

2002 ◽  
Author(s):  
Marcelo Assato ◽  
Marcelo J. S. de Lemos
Keyword(s):  
Heat Transfer ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Backward Facing Step ◽  
Simple Method ◽  
Wall Functions ◽  
Non Linear ◽  
Standard Linear ◽  
Experimental Values ◽  
Better Than

This work presents numerical results for heat transfer in turbulent flow past a backward-facing step. It is shown that nonlinear k-ε models perform better than their linear counterparts when simulations are compared with experimental values. Wall functions are used for simplicity of the simulations. The finite-volume technique is employed for discretizing the transport equation set on a non-orthogonal grid system. The SIMPLE method is used for correcting the pressure field. Results for the reattachment length using the non-linear model are closer to the experimental values when compared with similar calculations using the standard linear closure.

scholarly journals Coverage Evaluation on Probabilistically Linked Data

2015 ◽  
Vol 31 (3) ◽  
pp. 415-429 ◽  
Author(s):  
Loredana Di Consiglio ◽  
Tiziana Tuoto
Keyword(s):  
Administrative Data ◽  
Simulation Study ◽  
Record Linkage ◽  
Linked Data ◽  
Data Sources ◽  
Simple Method ◽  
Population Total ◽  
Linkage Error ◽  
Capture Recapture ◽  
Better Than

Abstract The Capture-recapture method is a well-known solution for evaluating the unknown size of a population. Administrative data represent sources of independent counts of a population and can be jointly exploited for applying the capture-recapture method. Of course, administrative sources are affected by over- or undercoverage when considered separately. The standard Petersen approach is based on strong assumptions, including perfect record linkage between lists. In reality, record linkage results can be affected by errors. A simple method for achieving linkage error-unbiased population total estimates is proposed in Ding and Fienberg (1994). In this article, an extension of the Ding and Fienberg model by relaxing their conditions is proposed. The procedures are illustrated for estimating the total number of road casualties, on the basis of a probabilistic record linkage between two administrative data sources. Moreover, a simulation study is developed, providing evidence that the adjusted estimator always performs better than the Petersen estimator.

Simple method of measuring vibration amplitudes at better than nanometer sensitivity

1988 ◽  
Vol 59 (12) ◽  
pp. 2626-2628 ◽  
Author(s):  
T. J. Greaves ◽  
F. L. Curzon
Keyword(s):  
Simple Method ◽  
Better Than

Effects of State-Trait Anxiety and Task Difficulty on Paired-Associate Learning

1977 ◽  
Vol 41 (1) ◽  
pp. 179-185 ◽  
Author(s):  
Robert A. Reeves ◽  
William W. May
Keyword(s):  
Paired Associate ◽  
Paired Associate Learning ◽  
Post Treatment ◽  
Associate Learning ◽  
Trait Theory ◽  
Learning Tasks ◽  
Treatment Conditions ◽  
Pre Treatment ◽  
Trait Groups ◽  
Better Than

The prediction from state-trait theory and drive theory that high A-State subjects will perform better than low A-State subjects on an easy task and more poorly on a more difficult task was tested using paired-associate learning tasks. This prediction was not supported, as low A-State subjects made fewer errors than high A-State subjects on both the easy and difficult tasks. High A-Trait groups responded with higher A-State in both pre- and post-treatment conditions than did low A-Trait groups as predicted by state-trait theory. Low A-Trait groups showed greater gains in pre-treatment to post-treatment A-State than did high A-Trait groups, a result which supported neither state-trait theory nor Saltz's (1970) hypothesis. Implications for research were discussed.

Two psychological treatments for hypochondriasis

1998 ◽  
Vol 173 (3) ◽  
pp. 218-225 ◽  
Author(s):  
David M. Clark ◽  
Paul M. Salkovskis ◽  
Ann Hackmann ◽  
Adrian Wells ◽  
Melanie Fennell ◽  
...  
Keyword(s):  
Stress Management ◽  
Cognitive Therapy ◽  
Specific Treatment ◽  
Post Treatment ◽  
Waiting List ◽  
Control Group ◽  
One Year ◽  
Almost All ◽  
Better Than

BackgroundHypochondriasis is generally considered difficult to manage. This study aimed to assess the effectiveness of cognitive therapy and to compare it with an equally credible, alternative treatment.MethodForty-eight patients with hypochondriasis were initially randomly assigned to either cognitive therapy, behavioural stress management or a no treatment waiting list control group. At the end of the waiting period, patients in the control group were randomly assigned to one of the two treatments. Assessments were at pre-, mid- and post-treatment or waiting list and at three-, six- and 12-month post-treatment follow-up.ResultsComparisons with the waiting list group showed both treatments were effective. Comparisons between the treatments showed that cognitive therapy was more effective than behavioural stress management on measures of hypochondriasis, but not general mood disturbance at mid-treatment and at post-treatment. One year after treatment patients who had received either treatment remained significantly better than before treatment, and on almost all measures the two therapies did not differ from each other.ConclusionsCognitive therapy is a specific treatment for hypochondriasis. Behavioural stress management is also effective but its specificity remains to be demonstrated.

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