scholarly journals Role of chemiluminescence and radius of curvature in the stabilization of methane/helium lifted flames

2018 ◽  
Vol 36 (4) ◽  
pp. 1249-1255
Author(s):  
Narayan P. Sapkal
Keyword(s):  
Radius Of Curvature ◽  
Lifted Flames

scholarly journals The Role of Axial Length-Corneal Radius of Curvature Ratio in Refractive State Categorization in a Nigerian Population

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Eghosasere Iyamu ◽  
Joy Iyamu ◽  
Christian Izuchukwu Obiakor
Keyword(s):  
Axial Length ◽  
Inverse Correlation ◽  
Radius Of Curvature ◽  
Spherical Equivalent ◽  
Refractive State ◽  
Spherical Equivalent Refraction ◽  
Nigerian Population ◽  
Corneal Radius ◽  
The Mean

The aim of this study was to investigate the association of axial length (AL)/corneal radius of curvature (CRC) ratio (AL/CRC) with spherical equivalent refractive state (SER) in young adults. A total of seventy () subjects consisting of 31 males and 39 females participated in this study. Subjects were categorized into emmetropia, hyperopia and myopia using the spherical equivalent refraction. The axial length was measured with I-2100 A-Scan ultrasonography/Biometer (CIMA Technology, USA), the corneal radius of curvature with Bausch & Lomb H-135A (Bausch & Lomb Corp., USA), and the refractive state by static retinoscopy and subjective refraction. The mean AL, CRC and AL/CRC ratio of all subjects were 23.74 ± 0.70 mm, 7.84 ± 0.19 mm, and 3.03 ± 0.14, respectively. Myopes had significantly longer AL, steeper CRC and higher AL/CRC ratio than the emmetropes and hyperopes. There was statistically significant inverse correlation between AL and CRC (, ), SER (, ), and between SER and AL/CRC (, ). A significant positive correlation was found between CRC and SER (, ). The categorization of the refractive state of an individual is better done by using the AL/CRC ratio index.

The Role of Grain Tip Radius in Fine Grinding

1975 ◽  
Vol 97 (3) ◽  
pp. 1119-1125 ◽  
Author(s):  
G. K. Lal ◽  
M. C. Shaw
Keyword(s):  
Grain Size ◽  
Surface Finish ◽  
Chip Thickness ◽  
Radius Of Curvature ◽  
Undeformed Chip Thickness ◽  
Fine Grinding ◽  
Abrasive Grains ◽  
Grinding Conditions ◽  
Tip Radius

The scratches produced by single abrasive grains in overcut fly milling show that the transverse shape of a grain is closely approximated by an arc of a circle. This radius of curvature is found to be independent of grain type and grinding conditions but varies with the grain size. The equation for undeformed chip thickness for surface grinding is rederived in terms of this radius. The important role that the transverse curvature of the grain plays relative to surface finish is also discussed.

Feed adjustment when milling curved surfaces

2019 ◽  
pp. 14-24
Author(s):  
E.Y. Matasova ◽  
D.V. Vinogradov
Keyword(s):  
Scientific Literature ◽  
Radius Of Curvature ◽  
Curved Surfaces ◽  
Flat Surfaces ◽  
Maximum Thickness ◽  
Manufacturing Operations ◽  
Milling Machines ◽  
One Machine ◽  
Range Of Values

Recently, there has been a trend to perform most manufacturing operations on one machine-tool. Such technology requires machining various internal and external cylindrical surfaces using not turning but milling machines. However, the role of feed in milling curved surfaces is not sufficiently studied in the scientific literature. The developed calculation method makes it possible to study the influence of milling parameters for curved surfaces on the maximum thickness of the cut layer. It is established that when milling convex surfaces, the maximum thickness of the cut layer decreases relative to that for plane milling, while for concave surfaces it increases. Equations are obtained for calculating feed per tooth for the cut layer thickness when milling curved surfaces. It is shown that the feed calculated for milling flat surfaces cannot be used for curved surfaces and, therefore, should be adjusted. The relative radius of curvature and the relative thickness of milling have an impact on the feed adjustment. The smaller these values, the larger the value of the feed adjustment should be. The range of values that requires feed re-calculation relative to the feed for flat milling is determined.

The Effect of Moore&s Law on the Growing Role of Transmission Electron Microscopy in the Semiconductor Industry

2001 ◽  
Vol 7 (S2) ◽  
pp. 510-511
Author(s):  
John Mardinly
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cross Sections ◽  
Semiconductor Device ◽  
Semiconductor Industry ◽  
Radius Of Curvature ◽  
Transmission Electron ◽  
Frequency Of Use ◽  
Pass Through

TEM has been used for semiconductor device characterization since the 1980's, when Marcus and Cheng first demonstrated the feasibility and utility of applying TEM to semiconductors. The frequency of use of TEM has accelerated briskly due to the continual shrinkage of devices as predicted by Gordon Moore and now documented in the SIA roadmap (http://public.itrs.net/Home.htm). TEM use has also grown due to application of FIB techniques which make possible high precision cross-sections of specific structures. This relentless shrinking has resulted in difficulties in preparing suitable specimens. Many of the features and interfaces in a device may be curved rather than planar, and as the radius of curvature begins to approach the thickness of a TEM specimen, it can result in “geometrical blurring” of features, both for imaging and microanalysis. The origin of this blurring is illustrated in Figure 1, where it can be seen that a single electron may pass through two different features, and as a result, they are not resolved.

Corotating or Codeforming Models for Thermoforming: Free Forming

2013 ◽  
Author(s):  
H. M. Baek ◽  
A. J. Giacomin
Keyword(s):  
Differential Equation ◽  
Analytical Solution ◽  
Maxwell Model ◽  
Radius Of Curvature ◽  
Disk Radius ◽  
Differential Model ◽  
Sheet Deformation ◽  
Sheet Curvature ◽  
Upper Convected Maxwell Model

Our previous work [J Pol Eng, 32, 245 (2012)] explores the role of viscoelasticity for the simplest relevant problem in thermoforming, the manufacture of cones. In this previous work, we use a differential model employing the corotational derivative [the corotational Maxwell model (CM)] for which we find an analytical solution for the sheet deformation as a function of time. This previous work also identifies the ordinary nonlinear differential equation corresponding to the upper convected Maxwell model (UCM), for which she finds no analytical solution. In this paper, we explore the role of convected derivative by solving this UCM equation numerically by finite difference. We extend the previous work to include sag by incorporating a finite initial sheet curvature. We treat free forming step in thermoforming and find that the convected derivative makes the free forming time unreasonably sensitive to the initial curvature. Whereas, for the CM model, we get a free forming time that is independent of initial sheet curvature, so long as the sheet is nearly flat to begin with. We cast our results into dimensionless plots of thermoforming times versus disk radius of curvature.

Alveolar septal structure in different species

1994 ◽  
Vol 77 (3) ◽  
pp. 1060-1066 ◽  
Author(s):  
R. R. Mercer ◽  
M. L. Russell ◽  
J. D. Crapo
Keyword(s):  
Connective Tissue ◽  
Volume Fraction ◽  
Lung Parenchyma ◽  
Radius Of Curvature ◽  
Electron Microscopic ◽  
Vascular Perfusion ◽  
Lung Structure ◽  
Alveolar Duct ◽  
Alveolar Septa

Because the retractive forces due to surface tension decrease with increasing radius of curvature, there should be a greater contribution to lung recoil attributable to the stress-bearing role of elastic elements in the lung parenchyma of species with larger alveoli. To examine alterations in lung structure that may relate to this stress-bearing role, the lungs of mice, hamsters, rats, rabbits, rhesus monkeys, baboons, and humans were preserved by vascular perfusion of fixative. The number of alveoli per lung, alveolar radius of curvature, surface area, and volume were measured by serial section reconstruction. Electron-microscopic determinations were made of the volume fraction and thickness of the epithelium, interstitium, and endothelium and of the connective tissue fibers of the alveolar septa and the portions of alveolar septa that form the alveolar ducts. The thickness of the alveolar septal interstitium increased linearly with the increase in radius of curvature of alveoli. The increase in interstitial thickness in lungs with larger alveoli was paralleled by large increases in the volume of collagen and elastin fibers present in this space. Comparable changes in the thickness of connective tissue fibers in alveolar duct walls were also found. This study demonstrates species-related changes in the structure of alveolar septa and in lung collagen and elastin fibers that are consistent with connective tissue fibers having a greater stress-bearing role in both the alveolar septa and alveolar ducts of species with larger alveoli.

scholarly journals The role of peripheral ocular length and peripheral corneal radius of curvature in determining refractive error

2021 ◽  
Author(s):  
Saleh H.A. Alhussain ◽  
Edward A.H. Mallen ◽  
Niall C. Strang ◽  
Sven Jonuscheit
Keyword(s):  
Refractive Error ◽  
Radius Of Curvature ◽  
Corneal Radius

scholarly journals On the horseshoe conjecture for maximal distance minimizers

2018 ◽  
Vol 24 (3) ◽  
pp. 1015-1041 ◽  
Author(s):  
Danila Cherkashin ◽  
Yana Teplitskaya
Keyword(s):  
Convex Set ◽  
Minimal Length ◽  
Radius Of Curvature ◽  
Compact Set ◽  
Local Minimizers ◽  
One Dimensional ◽  
Connected Sets ◽  
Minimal Radius ◽  
Closed Connected Sets

We study the properties of sets Σ having the minimal length (one-dimensional Hausdorff measure) over the class of closed connected sets Σ ⊂ ℝ2 satisfying the inequality maxy∈M dist (y,Σ) ≤ r for a given compact set M ⊂ ℝ2 and some given r > 0. Such sets play the role of shortest possible pipelines arriving at a distance at most r to every point of M, where M is the set of customers of the pipeline. We describe the set of minimizers for M a circumference of radius R > 0 for the case when r < R ∕ 4 .98, thus proving the conjecture of Miranda, Paolini and Stepanov for this particular case. Moreover we show that when M is the boundary of a smooth convex set with minimal radius of curvature R, then every minimizer Σ has similar structure for r < R ∕ 5. Additionaly, we prove a similar statement for local minimizers.

scholarly journals Deformation of soap films pushed through tubes at high velocity

2010 ◽  
Vol 652 ◽  
pp. 529-539 ◽  
Author(s):  
BENJAMIN DOLLET ◽  
ISABELLE CANTAT
Keyword(s):  
Simple Model ◽  
High Velocity ◽  
Equilibrium Configuration ◽  
Hydraulic Diameter ◽  
Radius Of Curvature ◽  
Inertial Effects ◽  
Soap Films ◽  
Small Parameters ◽  
Tube Geometry

The behaviour of soap films pushed through tubes at large velocities, up to several metres per second, is investigated in this paper. The film shape deviates from its equilibrium configuration perpendicular to the walls and gets curved downstream. A simple model relates the radius of curvature of the film to the friction in the lubrication films touching the wall, and the scaling of Bretherton (J. Fluid Mech., vol. 10, 1961, pp. 166–188) holds up to surprisingly high velocities, at which the capillary and Weber numbers are no longer small parameters. The tube geometry is varied and accounted for through the notion of hydraulic diameter. A limit of stability of the films, beyond which they burst or evolve unsteadily, is predicted, and it quantitatively captures the observations. The new questions raised by our results on the dissipation in soap films are discussed, especially the role of Plateau borders and inertial effects.

scholarly journals Role of the Crystallographic Phase of NiTi Rotary Instruments in Determining Their Torsional Resistance during Different Bending Conditions

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6324
Author(s):  
Alessio Zanza ◽  
Marco Seracchiani ◽  
Rodolfo Reda ◽  
Dario Di Nardo ◽  
Gianluca Gambarini ◽  
...  
Keyword(s):  
Nickel Titanium ◽  
Radius Of Curvature ◽  
Maximum Torque ◽  
Torsional Resistance ◽  
Rotary Instruments ◽  
Significant Difference ◽  
Torsional Test ◽  
Torque Values ◽  
Niti Rotary Instruments

The aim of this study was to assess the role of the crystallographic phase of Nickel-titanium (NiTi) rotary instruments in determining their torsional resistance during different bending conditions, such as different degrees and angles of curvature. 200 F-One 20.04 instruments (Fanta Dental, Shanghai, China) were used, 100 austenitic instruments and 100 martensitic instruments. Each group was divided in 5 subgroups according to the different bending conditions (straight canal, 90° or 60° of curvature degrees and 3 mm or 5 mm of radius of curvature). The static torsional test was performed by using a device composed of an electric motor capable of recording torque values (N·cm); a vice used to secure the instruments at 3 mm from the tip; and artificial canals, which allow instruments to remain flexed during test. Each instrument was rotated at 500 rpm with a torque limit set to 5.5 Ncm until its fracture. Torque at Fracture (TtF) was registered. A scanning electron microscopy (SEM) observation was conducted. The collected data confirm that an increase in the angle of curvature and a decrease in the radius of curvature of the artificial canals lead to an increase of TtF values with a statistically significant difference (p < 0.05), both in the austenitic and martensitic groups. Regarding the comparison between austenitic and martensitic groups in the same bending condition, a statistically significant difference was found only when the torsional test was performed in the canals with the degrees of curvature of 90° and the radius of curvature of 3 mm and 5 mm, with the austenitic instruments showing a higher TtF than the martensitic ones. In conclusion, it can be stated that the crystallographic phase influences the maximum torque at fracture when the instruments are subjected to severe bending and that the radius of curvature significantly influences their torsional resistance.

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