Accuracy of customized abutment data superimposition according to the extent of scanning area

2021 ◽  
Author(s):  
Tae-Min Park ◽  
Chang-Mo Jung ◽  
Mi-Jung Yoon ◽  
Jung-Bo Huh ◽  
So-Hyoun Lee ◽  
...  
Keyword(s):  
Scanning Area

scholarly journals OCT angiography metrics predict intradialytic hypotension episodes in chronic hemodialysis patients: a pilot, prospective study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Giuseppe Coppolino ◽  
Adriano Carnevali ◽  
Valentina Gatti ◽  
Caterina Battaglia ◽  
Giorgio Randazzo ◽  
...  
Keyword(s):  
Chronic Hemodialysis ◽  
Dialysis Session ◽  
Intradialytic Hypotension ◽  
Inverse Association ◽  
Non Invasive ◽  
Kaplan Meier ◽  
Optimal Thresholds ◽  
Scanning Area ◽  
Before And After ◽  
Capillary Plexus

AbstractIn chronic hemodialysis (HD) patients, intradialytic hypotension (IDH) is a complication that increases mortality risk. We run a pilot study to analyzing possible relationships between optical coherence tomography angiography (OCT-A) metrics and IDH with the aim of evaluating if OCT-A could represent a useful tool to stratify the hypotensive risk in dialysis patients. A total of 35 eyes (35 patients) were analyzed. OCT-A was performed before and after a single dialysis session. We performed OCT-A 3 × 3 mm and 6 × 6 mm scanning area focused on the fovea centralis. Patients were then followed up to 30 days (10 HD sessions) and a total of 73 IDHs were recorded, with 12 patients (60%) experiencing at least one IDH. Different OCT-A parameters were reduced after dialysis: central choroid thickness (CCT), 6 × 6 mm foveal whole vessel density (VD) of superficial capillary plexus (SPC) and 6 × 6 mm foveal VD of deep capillary plexus (DCP). At logistic regression analysis, IDH was positively associated with baseline foveal VD of SCP and DCP, while an inverse association was found with the choroid. In Kaplan–Meier analyses of patients categorized according to the ROC-derived optimal thresholds, CCT, the 3 × 3 foveal VD of SCP, the 3 × 3 mm and 6 × 6 mm foveal VD of DCP and the 6 × 6 mm foveal VD of SCP were strongly associated with a higher risk of IDH over the 30-days follow-up. In HD patients, a single OCT-A measurement may represent a non-invasive, rapid tool to evaluate the compliance of vascular bed to HD stress and to stratify the risk of IDH in the short term.

Research on Five-Axis Dual-NURBS Adaptive Interpolation Algorithm for Flank Milling

2010 ◽  
Vol 443 ◽  
pp. 330-335 ◽  
Author(s):  
Yu Han Wang ◽  
Jing Chun Feng ◽  
Sun Chao ◽  
Ming Chen
Keyword(s):  
Tool Path ◽  
Flank Milling ◽  
Interpolation Algorithm ◽  
Machining Time ◽  
Surface Machining ◽  
Tool Axis ◽  
Scanning Area ◽  
Nurbs Interpolation ◽  
Milling Method ◽  
Five Axis

In order to exploit the advantages of five-axis flank milling method for space free surface machining to the full, a definition of non-equidistant dual-NURBS tool path is presented first. On this basis, the constraint of velocity of points on the tool axis and the constraint of scanning area of the tool axis are deduced. Considering both of these constraints, an adaptive feed five-axis dual-NURBS interpolation algorithm is proposed. The simulation results show that the feedrate with the proposed algorithm satisfies both of the constraints and the machining time is reduced by 38.3% in comparison with the constant feed interpolator algorithm.

Line-Shaped Electron Beam System and Soi Films Prepared by The System

1985 ◽  
Vol 45 ◽  
Author(s):  
Y. Hayafuji ◽  
A. Shibata ◽  
T. Yanada ◽  
A. Sawada ◽  
S. Usui ◽  
...  
Keyword(s):  
Electron Beam ◽  
Crystalline Silicon ◽  
Semiconductor Industry ◽  
High Energy ◽  
Silicon Films ◽  
High Energy Density ◽  
Present System ◽  
Single Crystalline ◽  
Beam System ◽  
Scanning Area

ABSTRACTThe line-shaped electron beam annealing system which generates an electron beam of a length of 4 cm and a width af less than 100 um with a high energy density exceeding well over 100 kW/cm2 was developed for the first time with a purpose of SOI processing as its primary application. An pccelaration voltage of up to 20 kV can be used in this system. Seeded single crystalline islands with areas several mm long and 30 to 100 um in width were obtained by a single scan of the electron beam. The electron beam is generated in a pulsed way in the system due to the power restriction of the power supplies. An area of 4×5 cm2 was processed by a single scan of an electron beam at a sample speed of 530 cm/sec and a beam duration of 9.5 msec. The scanning area for one scan is determined by the beam length and the duration of the beam and sample speed.The present system could give single crystalline silicon films without any grain boundaries. The electron mobility of the electron beam recrystallized films, obtained from FETs made as a vehicle to test the electrical properties of the films, was comparable to that of the bulk silicon. A very rapid migration of silicon atoms in solid polycrystalline silicon films, which is controllable by process parameters, was also found with a migration speed of the order of 1 m/sec in a capped structure. The present electron beam system is useful in studying basic mechanisms of crystal growth in thin films. The system can have a very high throughput, a desirable feature in semiconductor industry. The present system can also be used to study the rapid thermal treatment of materials other than semiconductors including rapidly solidified materials.

Large scanning area near field optical microscopy

1998 ◽  
Vol 69 (10) ◽  
pp. 3614-3617 ◽  
Author(s):  
P. K. Wei ◽  
W. S. Fann
Keyword(s):  
Optical Microscopy ◽  
Near Field ◽  
Scanning Area

DIRECTIONAL DIFFUSION OF K ATOMS ON A GaAs(110) SURFACE

2006 ◽  
Vol 05 (06) ◽  
pp. 895-900 ◽  
Author(s):  
NOBUYUKI ISHIDA ◽  
AGUS SUBAGYO ◽  
KAZUHISA SUEOKA
Keyword(s):  
Dipole Moment ◽  
Electric Field ◽  
Radial Direction ◽  
Negative Sample ◽  
Directional Diffusion ◽  
Sample Bias ◽  
Induced Dipole ◽  
High K ◽  
Scanning Area ◽  
The Relationship

We performed STM measurements on the K/GaAs (110) surface with high K coverage. The K atoms gradually disappeared while scanning the tip over the surface at negative sample bias voltage. The phenomenon strongly occurred over the scanning area and can be explained by the field-induced surface diffusion from the scanning area to radial direction. Considering the interaction between the dipole moment of the adsorbed K atoms and the electric field, we discuss the relationship between the static and induced dipole moment of K atoms on a GaAs (110) surface.

Broadband wide-angle active phased L-band antenna array emitters

Antennas ◽  
2021 ◽  
Author(s):  
N. V. Samburov ◽  
R. O. But
Keyword(s):  
Antenna Array ◽  
Frequency Band ◽  
Mutual Influence ◽  
Wide Angle ◽  
Structural Elements ◽  
Scanning Area ◽  
Phased Antenna Array ◽  
Working Frequency ◽  
L Band ◽  
Spurious Emission

The purpose of this article is to review and justify the choice of emitters for constructing energy-efficient high-performance broadband active phased L-band antenna array with wide-angle scanning in 2 planes. Phased antenna array characteristics, accepted as reference: wide scan angle in the H-plane  not less than ± 450; a wide range of frequencies  at least 40%; small overall dimensions of the radiating aperture, not allowing to consider the canvas without taking into account edge effects; high energy potential, which means high electric strength (up to 1 kW per channel); reduced spurious emission outside the scanning area (more than 45 °). Here are the requirements for the emitters of the above-described active phased antenna array: Emitters dimensions must comply with the structural requirements for the antenna array construction (array step, emitters arrangement method) and not «obscure» each other in the area of the working scanning angles in the E and H plane. Emitters spatial bottom width in the grating should not be less than the angular width of the area of electronic scanning of the active phased antenna array beam. Beam main lobe distortion in the scanning area by an amount higher than 1 dB is not allowed. The emitter in the grating should be consistent with the power system in the working range of scanning angles and frequencies. Reduced spurious emission in directions outside the scanning area. High efficiency, to ensure both reception and transmission, and sufficient dielectric strength with limited dimensions. As active phased antenna array emitters, the simplest weakly directional antennas are used, which is associated with their low cost and high manufacturability. Technical solutions in the class of vibrator antennas (dipoles) are subjected to further analysis. The use of dipole antenna arrays in wide-angle and broadband applications leads to a number of technical limitations, such as: limited broadband emitters (including and as part of the antenna array), determined by their design features and mutual influence; a limited sector of the formation of unidirectional radiation (shape stability (radiation pattern) in the frequency band, determined by the condition for the appearance of interference lobes and the mutual influence of the emitters, leading to distortion of the amplitude-phase distribution; the occurrence of the effect of «blinding» of the lattice in individual sectors of the scan and frequencies associated with the effects of external (spatial) and internal interaction of emitters. Based on the above requirements for emitters, taking into account the design features of the AFAR, the following most important technical problems can be identified, the solution of which must be considered: ensuring a wide working frequency band; ensuring consistency in a wide sector of scanning angles; ensuring a stable spatial pattern of the emitter in the grating. Consider the general constructive methods that can be used to solve the above problems. Group them according to the constituent structural elements of the vibrator: Shoulders shape of the vibrators. The main limitation of the classical symmetric vibrator emitter using is its small working frequency band (up to 10%). So the passband ( 2f ) of a symmetric half-wave vibrator can be estimated by the following expression [5, p. 187]: 4 73,1 2 f f0 ,  WВ where is WВ  the wave impedance of the vibrator. It is determined by the cross section, shape and length of the shoulders. Balancing device type. Using a coaxial line determines the presence of balancing devices to power the shoulders of the vibrators. In the decimeter range, various types of balancing devices are used, the basis of which are various loops (including the U-elbow), glasses, transformers and slots, as well as their combinations. 3. Reflector shape (including matching structural elements). In fixed sector vibrator headlamps, a solid conductive surface is usually used as a reflector. Its shape and location relative to the shoulders has a strong effect on the bottom of the emitter in the grating and the matching of the grating in wide scanning angles and in the frequency range. The factor taking into account the influence of a flat aperiodic reflector on the DN is estimated by the expression: Fра  sin(kdr cos ) , where is dr  the distance from the vibrator to the reflector.

scholarly journals Laser ultrasonic imaging of wavefield spatial gradients for damage detection

2020 ◽  
pp. 147592172095133
Author(s):  
Zihan Wu ◽  
See Yenn Chong ◽  
Michael D Todd
Keyword(s):  
Laser Scanning ◽  
Ultrasonic Imaging ◽  
Image Processing Technique ◽  
Spatial Gradient ◽  
Spatial Covariance ◽  
Laser Ultrasonic ◽  
Spatial Gradients ◽  
Orientation Map ◽  
Scanning Area ◽  
Damage Visualization

This article describes a new damage visualization method to investigate and analyze propagating guided Lamb waves using analyses of wavefield spatial gradients. A laser ultrasonic interrogation system was used to create full-field ultrasonic data measurements for ultrasonic wavefield imaging. The laser scanning process was performed based on both a raster scan and a circle scan. From the high-resolution wavefield data, a spatial gradient–based image processing technique was developed using gradient vectors to extract features sensitive to defects. Local impedance changes at the damaged area would result in a local distortion of the waveform which was captured and quantified by the variation of the gradient vectors in the scanning area as time evolves. Such variation was accumulated over time with a statistical threshold filter to generate a gradient-orientation map for damage visualization. The proposed algorithm was capable of producing distinctive damage patterns when tested experimentally on a 3-mm aluminum plate with multiple simultaneous simulated defects. Compared to conventional techniques like local wavenumber estimation, the generation of the accumulated orientation map involves no filtering process in the frequency or wavenumber domain, at the expense of more accurate shaping of the defect. A spatial covariance analysis was adopted to locate damage from the results as well as to evaluate the correlation between different kinds of defects. Combining the proposed approach with conventional laser ultrasonic imaging techniques enables a fast and robust damage identification and characterization process which requires lower computational burden and practical operation.

442 ULTRASONOGRAPHIC TESTICULAR ECHOTEXTURE IN NELORE BULLS

2010 ◽  
Vol 22 (1) ◽  
pp. 378
Author(s):  
D. S. Costa ◽  
F. J. C. Faria ◽  
J. C. Borges
Keyword(s):  
Tunica Albuginea ◽  
Specific Area ◽  
Mato Grosso ◽  
Ultrasound Waves ◽  
Scanning Area ◽  
Significant Difference ◽  
Lilliefors Test ◽  
Pixel Value ◽  
Portable Ultrasonography ◽  
The Right

The objective of this research was to determine the minimum area representative of the testicular parenchyma echotexture in Nelore bulls, and to evaluate the presence of echotexture homogeneity between the right and left testicles and between different regions of testicle. Twenty-nine Nelore bulls raised under extensive management and free of reproductive disorders were used. The average body weight was 352.8 ± 51.0 kg and age ranged between 18 and 24 months. Echotexture was assessed using a portable ultrasonography device equipped with a 7.5-MHz linear transducer. All measurement was done by a single, experienced operator, and scanner settings that affect image attributes (i.e. proximal, distal, and total gains; focus area; brightness and contrast) were standardized to predetermined values. In the examinations, a layer of gel was applied to the transducer scanning area, which was positioned in the testicular longitudinal plane, proceeding with enough pressure to capture an image. The frozen images were obtained with minimal artifacts (refraction, dispersion, and attenuation of ultrasound waves) taking care to avoid the mediastinum testis and tunica albuginea, and recorded as .bmp files in a USB pen drive connected to the ultrasound device. Echotexture was defined in terms of mean pixel value quantified using values from 0 (black) to 255 (white) through the ImageJ 1.41 software. After the selection of a specific area of testicular parenchyma, the average tonality of the gray pixels in the selected region was calculated by the software and expressed in 256 gray-scales. Squares selections of 400 (20 × 20), 1600 (40 × 40), 3600 (60 × 60), and 6400 (80 × 80) pixels were assessed from images of the extremitas capitata, middle, and extremitas caudata regions of both testicles to determine the minimum sampling area of an image needed to represent the echotexture of testicular parenchyma. The normal distribution verification (Lilliefors test) of the variable mean pixel value was tested in each area, followed by variance analysis. The averages were compared through Tukey’s test with 5% significance. There was no significant difference between the different pixel areas assessed (P > 0.05), indicating that all were samples representative of testicular echotexture. Furthermore, the extremitas capitata, middle, and extremitas caudata regions showed no significant difference in echotexture (P > 0.05) regardless of the area analyzed, and there was no significant difference between the right and left testicles (P > 0.05) in any of the assessed areas. In conclusion, this research shows that testicular echotexture assessments can be made in Nelore bulls through selections of 400, 1600, 3600, or 6400 pixels, and that images can be captured from any region of any testicle. Fundect - Fundação deApoio ao Desenvolvimento do Ensino, CiÊncia e Tecnologia do Estado de Mato Grosso do Sul.

18. Small saccades restrict visual scanning area in Parkinson’s disease

2012 ◽  
Vol 123 (9) ◽  
pp. e91
Author(s):  
Hideyuki Matsumoto ◽  
Yasuo Terao ◽  
Toshiaki Furubayashi ◽  
Akihiro Yugeta ◽  
Hideki Fukuda ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Visual Scanning ◽  
Scanning Area
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