Extension of measurement area of stereo deflectometry

2021 ◽  
Author(s):  
Yurong Ren ◽  
Xiangchao Zhang ◽  
Wei Wang ◽  
Shaoliang Li ◽  
Xinyue Liu ◽  
...  
Keyword(s):  
Measurement Area

HVPE-GROWN AlGaN/GaN HEMTs

2003 ◽  
Vol 764 ◽  
Author(s):  
B. Luo ◽  
F. Ren ◽  
M. A. Mastro ◽  
D. Tsvetkov ◽  
A. Pechnikov ◽  
...  
Keyword(s):  
High Electron Mobility Transistors ◽  
Hydride Vapor Phase Epitaxy ◽  
Root Mean Square Roughness ◽  
High Electron ◽  
Electron Mobility Transistors ◽  
Current Collapse ◽  
Collapse Characteristics ◽  
Capacitance Voltage ◽  
Source Current ◽  
Measurement Area

AbstractHigh quality undoped AlGaN/GaN high electron mobility transistors(HEMTs) structures have been gorwn by Hydride Vapor Phase Epitaxy (HVPE). The morphology of the films grown on Al2O3 substrates is excellent with root-mean-square roughness of ∼0.2nm over 10×10μm2 measurement area. Capacitance-voltage measurements show formation of dense sheet of charge at the AlGaN/GaN interface. HEMTs with 1μm gate length fabricated on these structures show transconductances in excess of 110 mS/mm and drain-source current above 0.6A/mm. Gate lag measurements show similar current collapse characteristics to HEMTs fabricated in MBE- or MOCVD grown material.

scholarly journals Impact on Ultrafine Particles Concentration and Turbulent Fluxes of SARS-CoV-2 Lockdown in a Suburban Area in Italy

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 407
Author(s):  
Antonio Donateo ◽  
Adelaide Dinoi ◽  
Gianluca Pappaccogli
Keyword(s):  
Ultrafine Particles ◽  
Particle Number ◽  
Ultrafine Particle ◽  
Turbulent Fluxes ◽  
Number Concentration ◽  
Suburban Area ◽  
Observation Site ◽  
Meteorological Forcing ◽  
Restrictive Measures ◽  
Measurement Area

In order to slow the spread of SARS-CoV-2, governments have implemented several restrictive measures (lockdown, stay-in-place, and quarantine policies). These provisions have drastically changed the routines of residents, altering environmental conditions in the affected areas. In this context, our work analyzes the effects of the reduced emissions during the COVID-19 period on the ultrafine particles number concentration and their turbulent fluxes in a suburban area. COVID-19 restrictions did not significantly reduce anthropogenic related PM10 and PM2.5 levels, with an equal decrement of about 14%. The ultrafine particle number concentration during the lockdown period decreased by 64% in our measurement area, essentially due to the lower traffic activity. The effect of the restriction measures and the reduction of vehicles traffic was predominant in reducing concentration rather than meteorological forcing. During the lockdown in 2020, a decrease of 61% in ultrafine particle positive fluxes can be observed. At the same time, negative fluxes decreased by 59% and our observation site behaved, essentially, as a sink of ultrafine particles. Due to this behavior, we can conclude that the principal particle sources during the lockdown were far away from the measurement site.

Enhancing and Tuning broadband near-infrared (NIR) photoluminescence properties in Cr3+-doped Ca2YHf2Al3O12 garnet phosphors via Ce3+/Yb3+-codoping for LED applications

2021 ◽  
Author(s):  
Qianqian Zhang ◽  
Guogang Li ◽  
Peipei Dang ◽  
Dongjie Liu ◽  
Dayu Huang ◽  
...  
Keyword(s):  
Near Infrared ◽  
Light Emitting Diode ◽  
Food Composition ◽  
Night Vision ◽  
Photoluminescence Properties ◽  
Light Emitting ◽  
Measurement Area

Near-infrared emitting phosphor-converted light-emitting diode (NIR pc-LED) attracts much attention as the promising applications in night vision, biosensor, food composition and freshness measurement area and so on, while the discovery...

Optimal measurement area of articulated coordinate measuring machine calculated by ant colony algorithm

2017 ◽  
Vol 25 (6) ◽  
pp. 1486-1493 ◽  
Author(s):  
胡 毅 HU Yi ◽  
江 超 JIANG Chao ◽  
黄 炜 HUANG Wei ◽  
胡鹏浩 HU Peng-hao
Keyword(s):  
Ant Colony Algorithm ◽  
Coordinate Measuring Machine ◽  
Ant Colony ◽  
Optimal Measurement ◽  
Measuring Machine ◽  
Measurement Area

scholarly journals The Difference in Repeatability of Automated Superficial Retinal Vessel Density according to the Measurement Area Using OCT Angiography

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Hyung Bin Lim ◽  
Tae Seen Kang ◽  
Yeo Kyoung Won ◽  
Jung Yeul Kim
Keyword(s):  
Intraclass Correlation ◽  
Retinal Vessel ◽  
Vessel Density ◽  
Foveal Avascular Zone ◽  
Capillary Plexus ◽  
The Difference ◽  
Retinal Vessel Density ◽  
Perfusion Density ◽  
Measurement Area ◽  
Central Fovea

Purpose. To evaluate the difference in the repeatability of automated superficial retinal vessel density and foveal avascular zone (FAZ) metrics according to the measurement area of optical coherence tomography angiography (OCTA). Methods. A total of 127 normal eyes from 127 healthy subjects were included. Macular angiography images were acquired from all subjects using the Zeiss Cirrus 5000 with AngioPlex™ OCTA software. Scans of 3 × 3 mm and 6 × 6 mm were each performed twice in a randomly arranged sequence. Vessel density (VD), perfusion density (PD), and FAZ metrics of the superficial capillary plexus were calculated automatically for all scans, and the repeatabilities for both scan patterns were assessed based on intraclass correlation (ICC), coefficient of variation (CV), and coefficient of repeatability (CR) parameters. The average measured values in the two scan patterns were also compared. Results. VD was significantly greater in the 3 × 3 mm scan than in the 6 × 6 mm scan according to all parameters, whereas PD was significantly less in the 3 × 3 mm scan than in the 6 × 6 mm scan. The ICCs for VDs in the central fovea were 0.826 and 0.741 for the 3 × 3 and 6 × 6 mm scans, respectively, and the CVs were 8.00% and 12.75%. For PDs, the ICCs were 0.839 and 0.762 and the CVs were 9.32% and 14.90%. The FAZ metrics in the 3 × 3 mm scan showed good repeatability with an ICC >0.75 and a CV <10.0%. However, all ICCs for the 6 × 6 mm scans were <0.75, and the CVs were all >10%. Conclusions. The 6 × 6 mm macular angiography scans resulted in lower repeatabilities than the 3 × 3 mm scans according to all OCTA parameters, particularly in the central fovea and FAZ metrics. The 3 × 3 mm scan was more suitable than the 6 × 6 mm scan for analyzing macular microvascular density and FAZ metrics.

Application of Optical Scanning and Photogrammetry for Evaluation of Geometrical Tolerance Values

2013 ◽  
Author(s):  
Andrzej Gessner ◽  
Roman Staniek ◽  
Jakub Michałek
Keyword(s):  
Cross Sections ◽  
Optical Measurement ◽  
Measurement Techniques ◽  
Reference Method ◽  
Test Stand ◽  
Optical Methods ◽  
Test Surface ◽  
Test Plate ◽  
Optical Scanning ◽  
Measurement Area

The hereby presented research, funded by the restricted grant LIDER, NCBiR, deals, in part, with the identification of the full implementation potential of the proposed optical measurement techniques in determination of surface flatness parameters, and their comparative assessment. The test methods included the photogrammetric measurement technique (TRITOP, GOM) and the structural light scanning approach (scanner ATOS, GOM), while the CMM measurement (DEA Global Image Clima) was the reference method. The accordingly designed and assembled experimental test stand comprised 2 steel plates. The test surfaces of the plates were appropriately ground; subsequently, the entire test stand was blackened to ascertain efficient optical scanning. Furthermore, the plates were connected by means of 8 screws, thus introducing considerable distortion. A measurement area of 140 × 240 mm was defined on the plate test surface, as determined by CMM, denoting 15 measurement paths of 240 mm in length, distributed every 10 mm, and characterized by measurement point densities of 1, 5, and 20 pt/mm. The reference CMM measurements were conducted on 3 consecutive days at different times (22 measurements in total) to exclude any possible surface modifications. Subsequently, optical scanning was applied and the measurement points lying at the cross-sections of the CMM measurement paths were isolated from the obtained polygon mesh. To further apply the photogrammetric method, the test surface was labeled with markers distributed every 10 mm and coinciding with the CMM measurement paths. Comparative analysis of the flatness parameter for the selected CMM measurement and the measurement values obtained by means of the tested optical methods included: - the entire measurement area, - the sections comprising 80, 60, 50, 45, 40, 30, 20, 15, and 10 % of the entire measurement area, decreasing centrically, - the measurement sub-areas of 30 × 50 mm allotted in the corners and in the center of the test plate. The photogrammetric error of the tested parameter was established at 1.26–19.82 %, depending on the size of the measurement area. The corresponding error value, as determined by the structural light scanning technique, amounted to 0.03–4.31 %.

Sign in / Sign up

Export Citation Format

Share Document