The Diverging Collimator

1970 ◽  
Vol 09 (01) ◽  
pp. 84-94
Author(s):  
G. Muehllehner
Keyword(s):  
Unit Area ◽  
Field Of View ◽  
Imaging Camera ◽  
Good Agreement ◽  
Parallel Hole

SummaryThe diverging collimator makes it possible to increase the field of view of a radioisotope imaging camera. The larger field of view is obtained by sacrificing efficiency per unit area of the field of view while preserving the resolution of the system. This situation is analogous to that of the scanner, where the efficiency per unit area is inversely proportional to the total area scanned.Efficiency and resolution of diverging collimators can be calculated quite accurately as is evidenced by the good agreement between calculated and measured values. The problem of septum penetration, however, needs to be further investigated for both parallel-hole as well as diverging collimators, so that the influence of the shape and arrangement of the holes upon septum penetration is taken into account.

Tensile Properties of Triaxially Woven Fabrics Under Biaxial Loading

1980 ◽  
Vol 102 (4) ◽  
pp. 327-332 ◽  
Author(s):  
P. Schwartz ◽  
R. E. Fornes ◽  
M. H. Mohamed
Keyword(s):  
Tensile Properties ◽  
Biaxial Loading ◽  
Unit Area ◽  
Woven Fabrics ◽  
Experimental Results ◽  
Cover Factor ◽  
Axes Of Symmetry ◽  
Good Agreement ◽  
Loading Analysis

Classical results in the behavior of woven fabrics are extended to the case of fabrics having three planar, nonorthogonal axes of symmetry (triaxial). The biaxial loading analysis due to Grosberg is extended to the loading of triaxial fabrics in the machine and cross-machine directions in an attempt to predict fabric modulus during the crimp removal stage. Preliminary experimental results showing reasonably good agreement with moderately open fabrics are given. In addition, relationships are developed to allow the construction of conventional fabrics which are equivalent to triaxial fabrics in terms of cover factor and intersections or interfacings per unit area.

scholarly journals Non-contact smartphone-based fundus imaging compared to conventional fundus imaging: a low-cost alternative for retinopathy of prematurity screening and documentation

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Maximilian W. M. Wintergerst ◽  
Michael Petrak ◽  
Jeany Q. Li ◽  
Petra P. Larsen ◽  
Moritz Berger ◽  
...  
Keyword(s):  
Retinopathy Of Prematurity ◽  
Low Cost ◽  
Cost Effective ◽  
Field Of View ◽  
Fundus Examination ◽  
Fundus Imaging ◽  
Examination Time ◽  
Sensitivity Specificity ◽  
Rop Screening ◽  
Good Agreement

AbstractRetinopathy of prematurity (ROP) is a frequent cause of treatable childhood blindness. The current dependency of telemedicine-based ROP screening on cost-intensive equipment does not meet the needs in economically disadvantaged regions. Smartphone-based fundus imaging (SBFI) allows for affordable and mobile fundus examination and, therefore, could facilitate cost-effective telemedicine-based ROP screening in low-resources settings. We compared non-contact SBFI and conventional contact fundus imaging (CFI) in terms of feasibility for ROP screening and documentation. Twenty-six eyes were imaged with both SBFI and CFI. Field-of-view was smaller (ratio of diameters, 1:2.5), level of detail was equal, and examination time was longer for SBFI as compared to CFI (109.0 ± 57.8 vs. 75.9 ± 36.3 seconds, p < 0.01). Good agreement with clinical evaluation by indirect funduscopy was achieved for assessment of plus disease and ROP stage for both SBFI (squared Cohen’s kappa, 0.88 and 0.81, respectively) and CFI (0.86 and 0.93). Likewise, sensitivity/specificity for detection of plus disease and ROP was high for both SBFI (90%/100% and 88%/93%, respectively) and CFI (80%/100% and 100%/96%). SBFI is a non-contact and low-cost alternative to CFI for ROP screening and documentation that has the potential to considerably improve ROP care in middle- and low-resources settings.

scholarly journals Selection of the size of field of view in thermal imaging observations of small areas

2019 ◽  
Vol 28 ◽  
pp. 01040
Author(s):  
Krzysztof Dziarki ◽  
Arkadiusz Hulewicz ◽  
Zbigniew Krawiecki
Keyword(s):  
Temperature Distribution ◽  
Thermal Imaging ◽  
Field Of View ◽  
Thermal Imaging Camera ◽  
Small Areas ◽  
Imaging Camera ◽  
Single Detector ◽  
Selection Of

The paper explains the effect of matrix resolution on the field of view of a single detector. The dependency of the field of view of a single detector as a function of distance between the lens of thermal imaging camera and the surface observed is shown. It was proposed how to select the lens of thermal imaging camera so that the obtained thermogram it would be able to achieve such a geometric resolution that would allow for sufficiently accurate mapping of temperature distribution on the surface observed.

scholarly journals The diffusion of gases through metals

1935 ◽  
Vol 150 (869) ◽  
pp. 172-197 ◽  
Keyword(s):  
Unit Area ◽  
The Other ◽  
Effect Of Temperature ◽  
Metal System ◽  
The Subject ◽  
Temperature And Pressure ◽  
Theoretical Considerations ◽  
Diffusion Of Hydrogen ◽  
Good Agreement ◽  
Diffusion Of Gases

Since the original discovery by Graham in 1866 that hydrogen could diffuse through platinum, the phenomena of diffusion of gases through metals have been the subject of many investigations. Various empirical equations have been proposed to represent the effect of temperature and pressure on the rate of diffusion, and in 1904 Richardson, Nicol, and Parnell arrived at an equation from theoretical considerations which was in good agreement with their own measurements of the diffusion of hydrogen through platinum. This equation, generally known as Richard­ son’s equation, may be written D = k / d . P ½ T ½ e ─ b /T , (1) where D is the rate of diffusion per unit area of surface, P is the gas pressure, T the temperature, d the thickness of the metal, and b a constant for the gas-metal system. The equation applies to conditions in which gas is maintained at a pressure P on one side of the metal, whilst a vacuum is maintained on the other side. If instead of a vacuum a pressure P 1 , where P 1 < P, exists, the term √P in the equation is replaced by (√P ─ √P 1 ).

scholarly journals Non-Intrusive Luminance Mapping via High Dynamic Range Imaging and 3-D Reconstruction

2021 ◽  
Vol 2042 (1) ◽  
pp. 012113
Author(s):  
Michael Kim ◽  
Athanasios Tzempelikos
Keyword(s):  
Dynamic Range ◽  
Low Cost ◽  
High Dynamic Range ◽  
Field Of View ◽  
High Dynamic Range Imaging ◽  
3D Space ◽  
Short Video ◽  
High Dynamic ◽  
Daylighting Control ◽  
Good Agreement

Abstract Continuous luminance monitoring is challenging because high-dynamic-range cameras are expensive, they need programming, and are intrusive when placed near the occupants’ field-of-view. A new semi-automated and non-intrusive framework is presented for monitoring occupant-perceived luminance using a low-cost camera sensor and Structure-from- Motion (SfM)-Multiview Stereo (MVS) photogrammetry pipeline. Using a short video and a few photos from the occupant position, the 3D space geometry is automatically reconstructed. Retrieved 3D context enables the back-projection of the camera-captured luminance distribution into 3D spaces that are in turn re-projected to occupant-FOVs. The framework was tested and validated in a testbed office. The re-projected luminance field showed with good agreement with luminance measured at the occupant position. The new method can be used for non-intrusive luminance monitoring integrated with daylighting control applications.

Field-of-view enhancement for commercially available active imaging camera using time-of-flight technology

2018 ◽  
Author(s):  
Marc-Antoine Legault ◽  
Mathieu Gagnon ◽  
Simon Thibault ◽  
Anne-Sophie Poulin-Girard ◽  
Michael Smith
Keyword(s):  
Time Of Flight ◽  
Field Of View ◽  
Imaging Camera ◽  
Active Imaging

Observations on the development of the fleece and follicle population in Suffolk sheep

1954 ◽  
Vol 44 (1) ◽  
pp. 86-99 ◽  
Author(s):  
Marca Burns
Keyword(s):  
Body Weight ◽  
Surface Area ◽  
Fibre Type ◽  
Unit Area ◽  
Skin Samples ◽  
Good Agreement ◽  
Suffolk Sheep

Observations were made on four Suffolk lambs from birth to 14 months of age, wool and skin samples being taken periodically. The lambs were on a high nutritional plane and grew well throughout the experiment.1. There is good agreement between estimates of growth based on body weight, calculated surface area, and expansion of tattooed squares.2. Fibre Type Arrays were Valley or Plain.3. Benzene tests showed considerable medullation in the fleeces of all the lambs, mainly in the posterior parts. There were practically none on the shoulder.4. The weight of keratin produced daily per unit area of skin reached or exceeded the figure given as maximal by Galpin (1948) in only six samples, of which four were grown prior to 1 month old.5. The follicle population completes its development early, only a few secondary follicles being added after birth. The definitive S/P ratio is 5/, which is similar to the Leicester, and lower than in the Romney breed. The follicle density, although high at birth, is lower than in the Romney or Leicester, after 9 months old. Both S/P ratio and follicle density are higher than in the Blackface breed.6. The transitory black colour of the birth-coat of Suffolk lambs is due to pigmentation of the tips of many fibres; this may affect any type of fibre from haloes and sickles to histerotrichs. With very few exceptions all follicles cease to produce pigmented fibre at or shortly after birth of the lamb. Large amoebic melanoblasts are present in the skin.

Application of the Visual Fast Count for the quantification of temperate epibenthic communities from video footage

2006 ◽  
Vol 86 (5) ◽  
pp. 939-945 ◽  
Author(s):  
James Asa Strong ◽  
Matthew Service ◽  
Annika Jane Mitchell
Keyword(s):  
Substantial Reduction ◽  
Field Of View ◽  
Pairwise Comparisons ◽  
Video Footage ◽  
Use Of Time ◽  
Strangford Lough ◽  
Non Destructive ◽  
Epibenthic Communities ◽  
Good Agreement ◽  
Direct Counts

Video transects of epibenthic communities provide a valuable and non-destructive surveying methodology. The use of unstable platforms for video collection, such as divers and remotely operated vehicles, can lead to variation in the field of view, and consequently the dimensions of the surveyed area. Unless this can be accounted for, quantifying the species present can be time consuming or unworkable. Use of time-based, rather than areas-based, enumeration techniques, such as the visual fast count (VFC), can overcome this variation. Using seabed video footage from Strangford Lough, the reliability of the VFC was assessed through comparison with direct counts. Multivariate analysis of variance indicates that data derived from the VFC did not differ from that obtained from direct counts. Pairwise comparisons between locations in Strangford Lough using analysis of similarities (PRIMER) also indicated good agreement between the two methods. Use of the VFC method therefore provides: (1) a reliable alternative to direct counts for epibenthic enumeration; (2) a substantial reduction in post-survey processing time and; (3) a method capable of allowing variation in the visual field/sampled area.

scholarly journals Assessment of the Hyperspectral Infrared Atmospheric Sounder (HIRAS)

2019 ◽  
Vol 11 (24) ◽  
pp. 2950 ◽  
Author(s):  
Fabien Carminati ◽  
Xianjun Xiao ◽  
Qifeng Lu ◽  
Nigel Atkinson ◽  
James Hocking
Keyword(s):  
Standard Deviation ◽  
Spectral Resolution ◽  
Weather Prediction ◽  
Field Of View ◽  
Double Difference ◽  
Fourier Transform Spectrometer ◽  
Spectral Bands ◽  
Data Quality Assessment ◽  
Nwp Model ◽  
Good Agreement

The hyperspectral infrared atmospheric sounder (HIRAS), the first Chinese hyperspectral infrared instrument, was launched in 2017 on board the fourth polar orbiter of the Feng Yun 3 series, FY-3D. The instrument is a Fourier transform spectrometer with 2275 channels covering three spectral bands (650–1136, 1210–1750, and 2155–2550 cm−1) with 0.625 cm−1 spectral resolution. The first data quality assessment of HIRAS observations at full and normal spectral resolutions is presented. Comparisons with short-range forecasts from the Met Office numerical weather prediction (NWP) global system have revealed biases (standard deviation) generally less than 2.6 K (2 K) in the spectral regions mostly unaffected by trace gases where the confidence in the NWP model is largest. Of particular concern, HIRAS detector 3 seems to suffer from sunlight contamination of its calibration towards the end of the descending node. This, together with an obstruction of the detector field of view by an element of the platform, results in accentuated bias and noise in the observations from this detector. At normal spectral resolution, a background departure double difference analysis has been conducted between HIRAS and the NOAA-20 crosstrack infrared sounder (CrIS). The results show that HIRAS and CrIS are in good agreement with a mean difference across the three bands of −0.05 K (±0.26 K at 1σ) and 75.2% of the channels within CrIS radiometric uncertainty, noting though that HIRAS is noisier than CrIS with, on average, a standard deviation 0.34 K larger.

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