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Optical and visual metrics
Published in Pablo Artal, Handbook of Visual Optics, 2017
The full width at half maximum (FWHM) is an expression of the extent of the PSF given by the distance between points on the curve at which the intensity reaches half its maximum value. Half width at half maximum (HWHM) is half of the FWHM (Charman and Jennings 1976; Westheimer and Campbell 1962). If the PSF is expressed in polar coordinates, the HWHM is computed as the average width of every cross section of the PSF: HWHM=1π∫02π∫0∞Π(r,φ)rdrdφ
MEMS-Based Lamellar Grating Fourier Transform Spectrometers
Published in Vikas Choudhary, Krzysztof Iniewski, MEMS, 2017
Hongbin Yu, Guangya Zhou, Fook Siong Chau
The final spectrum is obtained by performing a complex Fourier transform on the recorded interferogram (as described earlier) and taking the modulus of the transform. From the results shown in Figure 12.11, it can be seen that two separate sharp peaks at 632.07 and 531.49 nm appear in the spectrum corresponding to the wavelengths of the two input laser beams. The spectral accuracy of the detected wavelengths is better than 1 nm. The full-width at half-maximum (FWHM) spectral resolution is determined to be around 3.8 nm at 632.8 nm wavelength, and 3.44 nm at 532 nm wavelength.
Antennae
Published in Le Nguyen Binh, Wireless And Guided Wave Electromagnetics, 2017
where Pant(θ, ϕ); Piso(θ, ϕ) are the power radiation over the surface or intensity distribution dependent on the solid angle of the antenna under consideration and the isotropic antenna, respectively. G(θ, ϕ) is the gain and relies on the intensity term and radiation pattern. Normally the intensity is calculated over the entire angle of the radiation pattern, from the peak to the half-power point (the full width at half maximum, FWHM).
Effects of variations in the tragus expansion angle on physical comfort for in-ear wearables
Published in Ergonomics, 2022
Mengcheng Wang, Hao Fan, Suihuai Yu, Xiao Zhao, Long Wang, Wenhua Li, Lei Wang, Mingjiu Yu, Jianjie Chu, Shuai Zhang, Dengkai Chen
Statistical analysis was conducted at α = 0.05 with Matlab R2018a, and p < 0.05 was considered statistically significant. The independent-samples t-test was performed to examine the differences between genders in the TEI of each ATMC prototype. The paired-samples t-test was conducted to examine the differences between both ears in terms of the ratings and corresponding TEI values. Gaussian peak function (GaussAmp) was employed to explore the (dis)comfort rating model of the TEI (Equations 3, 4). where is the offset, is the centre, is the width, and is the amplitude. FWHM means full width at half maximum.
Behaviors of Adsorption and Elution on Amidoxime Resin for Gallium, Vanadium, and Aluminium Ions in Alkaline Aqueous Solution
Published in Solvent Extraction and Ion Exchange, 2021
Qi Zheng, Chunlin He, Jiejie Meng, Toyohisa Fujita, Chunhui Zheng, Wei Dai, Yuezhou Wei
Fourier transformed infrared (FTIR) spectra of AO-resin before and after sorption were obtained on a Shimadzu-IR 100 spectrometer with KBr pellets at room temperature. Surface elements were investigated by X-ray photoelectron spectroscopy (XPS) using an ESCALAB 250XI spectrophotometer (Thermo Fisher Scientific, USA) equipped with a monochromatized Al-Kα X-ray source. The high-resolution X-ray photoelectron spectra peaks were analyzed using subcomponents by mixed Lorentzian-Gaussian functions through the XPS peak 4.1 software packages after subtraction of the Shirley-type background. During curve fitting, the line width (full width at half-maximum or fwhm) of the peaks was maintained constant for all components in a particular spectrum. Samples were referenced to the C1s sp2 peak at 284.6 eV.[27]
Enhanced adhesion property of aramid fibers by polyphenol-metal iron complexation and silane grafting
Published in The Journal of Adhesion, 2021
Lei Wang, Bo Zhang, Xue Li, Wencai Wang, Ming Tian, Zhaodong Fan, Liqun Zhang
Fourier transform infrared spectroscopy (FTIR) analysis was used to characterize the functional groups and bonding status of the PPTA fibers, which was performed in a Tensor 27 spectrophotometer in attenuated total reflectance (ATR) mode. All the spectra were acquired at a resolution of 4 cm−1 in the wavenumber range of 600–4000 cm−1. X-ray photoelectron spectroscopy (XPS) characterization was performed using a ESCALAB 250 with an Al Kα X-ray source working at 150 W. The emission angle for photoelectron is 45° with respect to the sample surface. All binding energies (BEs) were referenced to the C 1s hydrocarbon peak at 284.6 eV to compensate for surface charging effects. In peak fitting, the full width at half-maximum (FWHM) of Gaussian peaks was kept constant for all components in a spectrum. The residual of measured and fitted data for PPTA, PPTA-TA/FeIII and PPTA- TA/FeIII-Si69 are 37.7, 36.5 and 37.4, respectively. Thermo-gravimetric analysis (TGA) tests were conducted on a METTLER-TOLEDO analyzer. Fiber samples were heated under a continuous nitrogen flow at 10°C/min from 30°C to 800°C. The surface morphology of the fibers was characterized by scanning electron microscopy (SEM) at 5 kV accelerating voltage. Each sample was coated with a 10nm-thick layer of gold before measurement. The adhesion property of the aramid fibers was measured through the pull-out test according to ISO 4647:2010. The illustration of the test piece and the test piece grip are shown in Figure 2. The pull-out tests were carried out using a tensile strength tester with a speed of the movable grip of 100 mm/min±10 mm/min, and the direction of the applied force was along the longitudinal axis of the fibers. Data were treated and reported by presenting the arithmetic mean of the maximum pull-out forces of at least 10 specimens in each group.