scholarly journals A rapid and robust gradient measurement technique using dynamic single-point imaging

2016 ◽  
Vol 78 (3) ◽  
pp. 950-962 ◽  
Author(s):  
Hyungseok Jang ◽  
Alan B. McMillan
Keyword(s):  
Measurement Technique ◽  
Single Point ◽  
Gradient Measurement

Gradient measurement technique to identify phase transitions in nano-dispersed liquid crystalline compounds

2015 ◽  
Vol 89 (9) ◽  
pp. 902-909 ◽  
Author(s):  
P. Pardhasaradhi ◽  
B.T.P. Madhav ◽  
M. Venugopala Rao ◽  
R.K.N.R. Manepalli ◽  
V.G.K.M. Pisipati
Keyword(s):  
Phase Transitions ◽  
Measurement Technique ◽  
Liquid Crystalline ◽  
Gradient Measurement

scholarly journals 3D DEFORMATION MEASUREMENT OF CONCRETE WALL USING CLOSE-RANGE PHOTOGRAMMETRY

2020 ◽  
Vol XLIII-B2-2020 ◽  
pp. 1175-1179
Author(s):  
T.-A. Teo
Keyword(s):  
Measurement Technique ◽  
Surface Deformation ◽  
Single Point ◽  
Research Area ◽  
Deformation Monitoring ◽  
Concrete Wall ◽  
Dense Matching ◽  
Wall Deformation ◽  
Displacement Transducers ◽  
Photogrammetric Measurement

Abstract. Due to the development of digital image processing, digital photogrammetry is becoming an interesting research area in the field of structural monitoring in civil engineering. This study presents a photogrammetric measurement technique for concrete wall deformation monitoring in the destructive experiment. The non-contact photogrammetric measurement technique which provides surface deformation, is more flexible than the contacted single-point measurement technique (e.g., linear variable displacement transducers, LVDT). The major steps of the proposed scheme include (1) camera calibration, (2) orientation modeling, (3) 3D dense matching, and (4) filtering and interpolation for surface deformation. This experiment used two non-metric digital cameras to measure the deformation of a concrete wall in destructive experiment. The validation compared the image-derived and ranger-derived displacements during the experiment with mean error and standard errors of 32 epochs were −0.02mm and 0.81mm, respectively. The correlation between image-derived displacement and LVDT-derived displacement was 0.9803. The advantage of photogrammetry is to derive surface deformation which covered the whole wall during the experiment. In summary, this study demonstrated that photogrammetry is a useful measurement technique for concrete wall destructive experiment.

scholarly journals “One stop” liver-focused endoscopy: EUS-guided portal pressure gradient measurement technique

VideoGIE ◽  
2020 ◽  
Vol 5 (12) ◽  
pp. 658-659
Author(s):  
Shawn L. Shah ◽  
Qais Dawod ◽  
Sonal Kumar ◽  
Brett Fortune ◽  
Reem Z. Sharaiha
Keyword(s):  
Pressure Gradient ◽  
Measurement Technique ◽  
Portal Pressure ◽  
One Stop ◽  
Gradient Measurement

scholarly journals The Visual Measurement of Velocity Profile Distribution in Silt Carrying Flow by Using Ultrasound PIV and Iterative Multi-Grid Deformation Technique

2021 ◽  
Vol 11 (15) ◽  
pp. 6952
Author(s):  
Xianjian Zou ◽  
Wenbin Hu ◽  
Huan Song ◽  
Bingrui Chen
Keyword(s):  
Velocity Profile ◽  
Flow Velocity ◽  
Measurement Technique ◽  
Imaging System ◽  
Single Point ◽  
Interrogation Window ◽  
Measured Velocity ◽  
Visual Measurement ◽  
Grid Deformation ◽  
Profile Distribution

Flow velocity in silt carrying flow is one key parameter to many river engineering problems. A visual measurement technique of velocity profile distribution in silt carrying flow is provided using a portable ultrasound imaging system and an improved iterative multi-grid deformation algorithm. A convex array probe in the system is used to obtain a series of ultrasonic images at different times. Window offset and an iterative computing scheme for reducing interrogation window size in the algorithm improve the accuracy and efficiency of flow velocity measurement in regions with velocity gradients. Results show that the measured profile velocities can be more acceptable after being compared with time-averaged stream-wise velocities of profiles at ten positions in the same silt carrying flow and subsequently verified by comparing the point-by-point standard value. The measured velocity is more in agreement with the theoretical value, with the minimum root mean square error in the ultrasound beam sweep effect calculated by using optimal interrogation size parameters. The system is a feasible alternative to the single-point measurement technique in silt carrying flow. The iterative multi-grid deformation algorithm can analyze velocity profile distribution with gradients simultaneously, which can help the real-time measurement of multiple spatial velocity distribution and turbulence.

Fine-scale taxonomic and temporal variability in the energy density of invertebrate prey of juvenile Chinook salmon Oncorhynchus tshawytscha

2020 ◽  
Vol 655 ◽  
pp. 185-198
Author(s):  
J Weil ◽  
WDP Duguid ◽  
F Juanes
Keyword(s):  
Energy Density ◽  
Chinook Salmon ◽  
Temporal Variability ◽  
Energy Content ◽  
Single Point ◽  
Single Species ◽  
Fine Scale ◽  
Temporal Differences ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

Variation in the energy content of prey can drive the diet choice, growth and ultimate survival of consumers. In Pacific salmon species, obtaining sufficient energy for rapid growth during early marine residence is hypothesized to reduce the risk of size-selective mortality. In order to determine the energetic benefit of feeding choices for individuals, accurate estimates of energy density (ED) across prey groups are required. Frequently, a single species is assumed to be representative of a larger taxonomic group or related species. Further, single-point estimates are often assumed to be representative of a group across seasons, despite temporal variability. To test the validity of these practices, we sampled zooplankton prey of juvenile Chinook salmon to investigate fine-scale taxonomic and temporal differences in ED. Using a recently developed model to estimate the ED of organisms using percent ash-free dry weight, we compared energy content of several groups that are typically grouped together in growth studies. Decapod megalopae were more energy rich than zoeae and showed family-level variability in ED. Amphipods showed significant species-level variability in ED. Temporal differences were observed, but patterns were not consistent among groups. Bioenergetic model simulations showed that growth rate of juvenile Chinook salmon was almost identical when prey ED values were calculated on a fine scale or on a taxon-averaged coarse scale. However, single-species representative calculations of prey ED yielded highly variable output in growth depending on the representative species used. These results suggest that the latter approach may yield significantly biased results.

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