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Theoretical investigation of vanadium oxide film with surface microstructure

Hong W., Wang Z., Chen Q., Sheng C., Gu G., Luo P., Xie Y.

Optica Applicata

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2017

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Vol. 47, nr 4

601--609

EN

This paper presents a method to design a surface microstructure of vanadium oxide to enhance optical absorption. This method, using a density of eigenfrequency, can be calculated by a planar wave expand method, to indicate the absorption efficiency of a dispersion material, which can be used as an approach method for further design. Based on this, a nanostructure-based vanadium oxide film is designed and simulated to validate this method. The simulation results show that the tendency of density of eigenfrequency is corresponding to the tendency of optical absorption enhancement. Moreover, this structure can achieve high optical broadband absorption when the material dispersion is considered. High optical absorption enhancement can be achieved by adjusting the geometrical parameters; our maximum overall enhancement absorption ratio was 31.84% at the metal phase, which can be attributed to the enhancement effect of a photonic band edge.

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VO2(B) conversion to VO2(A) and VO2(M) and their oxidation resistance and optical switching properties

Zhang Y.

Materials Science Poland

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2016

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Vol. 34, No. 1

169--176

EN

Vanadium dioxide VO2 has been paid in recent years increasing attention because of its various applications, however, its oxidation resistance properties in air atmosphere have rarely been reported. Herein, VO2 (B) nanobelts were transformed into VO2 (A) and VO2 (M) nanobelts by hydrothermal route and calcination treatment, respectively. Then, we comparatively studied the oxidation resistance properties of VO2 (B), VO2 (A) and VO2 (M) nanobelts in air atmosphere by thermo-gravimetric analysis and differential thermal analysis (TGA/DTA). It was found that the nanobelts had good thermal stability and oxidation resistance below 341 degrees C, 408 degrees C and 465 degrees C in air, respectively, indicating that they were stable in air at room temperature. The fierce oxidation of the nanobelts occurred at 426, 507 and 645 degrees C, respectively. The results showed that the VO2 (M) nanobelts had the best thermal stability and oxidation resistance among the others. Furthermore, the phase transition temperatures and optical switching properties of VO2 (A) and VO2 (M) were studied by differential scanning calorimetry (DSC) and variable-temperature infrared spectra. It was found that the VO2 (A) and VO2 (M) nanobelts had outstanding thermochromic character and optical switching properties.

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The influence of 3D kinematic and electromyographical parameters on cycling economy

Sinclair J., Hebron J., Atkinson S., Hurst H., Taylor P. J.

Acta of Bioengineering and Biomechanics

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2014

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Vol. 16, no. 4

91--97

EN

Purpose: Economy is considered to be a key factor for the determination of performance in endurance events such as cycling. There have been no investigations which have related cycling economy to simultaneous measurements of 3D kinematics and muscular activation. This study examined selected biomechanical and neuromuscular parameters which have the strongest association with cycling economy. Methods: Twenty-five trained cyclists (31.27±3.19 years) completed steady state cycling time trials at a workload of 180 W. Simultaneous measurements of 3D kinematics and electromyographical parameters were obtained. Continuous measurements of expired gases were used to provide a measure of cycling economy. Results: A multiple regression analysis showed that key parameters of peak knee extension velocity and mean activity of the rectus femoris muscles were significant predictors of VO2 during steady state cycling (P<0.01). Conclusion: This study has documented the key biomechanical parameters pertinent to cycling economy. As economy has been shown to influence aerobic performance, future work should focus on optimising these parameters to improve cycling economy.

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Performance on a Work-Simulating Firefighter Test Versus Approved Laboratory Tests for Firefighters and Applicants

Von Heimburg E., Medbo J. I., Sandsund M., Reinertsen R. E.

International Journal of Occupational Safety and Ergonomics

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2013

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Vol. 19, No. 2

227--243

EN

Aim. Firefighters must meet minimum physical demands. The Norwegian Labour Inspection Authority (NLIA) has approved a standardised treadmill walking test and 3 simple strength tests for smoke divers. The results of the Trondheim test were compared with those of the NLIA tests taking into account possible effects of age, experience level and gender. Methods. Four groups of participants took part in the tests: 19 young experienced firefighters, 24 senior male firefighters and inexperienced applicants, 12 male and 8 female. Results. Oxygen uptake (VO2) at exhaustion rose linearly by the duration of the treadmill test. Time spent on the Trondheim test was closely related to performance time and peak VO2 on the treadmill test. Senior experienced firefighters did not perform better than equally fit young applicants. However, female applicants performed poorer on the Trondheim test than on the treadmill test. Performance on the Trondheim test was not closely related to muscle strength beyond a minimum. Conclusion. Firefighters completing the Trondheim test in under 19 min fit the requirements of the NLIA treadmill test. The Trondheim test can be used as an alternative to the NLIA tests for testing aerobic fitness but not for muscular strength. Women’s result of the Trondheim test were poorer than the results of the NLIA treadmill test, probably because of their lower body mass.