Geometric Modeling of the Nasal Valve

2017 ◽  
Vol 33 (04) ◽  
pp. 444-450 ◽  
Author(s):  
Wasnard Victor ◽  
Matthew Sclafani ◽  
Anthony Sclafani
Keyword(s):  
Geometric Modeling ◽  
Geometric Model ◽  
Geometric Analysis ◽  
Lateral Wall ◽  
Nasal Valve ◽  
Total Change ◽  
Cross Sectional ◽  
Cantilevered Beam ◽  
Nasal Function ◽  
Length Reduction

AbstractWe have used a simple geometric model to examine forces affecting the nasal valve after dorsal reduction and spreader graft placement. The study was designed on the geometric modeling of the internal nasal valve (INV). Published measurements of the leptorrhine nose were used to construct a geometric model of the INV. The changes in the cross-sectional area (CSA) occurring after reduction rhinoplasty were calculated algebraically, as was the effect of these changes on the tendency of the lateral wall of the INV to collapse. The effect of spreader grafting on the CSA was determined, and the total change in CSA of the INV in various scenarios was determined and compared with the reported normal CSA. Relative to published norms, the gain in CSA from spreader grafting can be significant if thick grafts are used. When the lateral wall of the INV is conceptualized as a cantilevered beam fixed medially, the reduction of length reduction of the lateral segment of the INV can significantly reduce the tendency for the inward collapse of the lateral wall. The reduction in CSA of the INV associated with dorsal nasal reduction can be ameliorated through the placement of spreader grafts. Moreover, the reduction in length of the INV sidewall also limits inward collapse, assuming it is firmly reattached to the dorsal septum. An enhanced appreciation of the physical properties of the INV anticipated through a simplified geometric analysis will be invaluable to the rhinological surgeon interested in enhancing nasal function.

BIOMECHANICAL MODEL PREDICTING VALUES OF MUSCLE FORCES IN THE SHOULDER GIRDLE DURING ARM ELEVATION

2010 ◽  
Vol 10 (04) ◽  
pp. 643-666 ◽  
Author(s):  
ERIC BERTHONNAUD ◽  
MELISSA MORROW ◽  
GUILLAUME HERZBERG ◽  
KAI-NAN AN ◽  
JOANNES DIMNET
Keyword(s):  
Geometric Modeling ◽  
Geometric Model ◽  
Contractile Element ◽  
Muscle Forces ◽  
Active Muscle ◽  
Cross Sectional ◽  
Shoulder Complex ◽  
Arm Elevation

A three-dimensional (3D) geometric model for predicting muscle forces in the shoulder complex is proposed. The model was applied throughout the range of arm elevation in the scapular plan. In vitro testing has been performed on 13 cadaveric shoulders. The objectives were to determine homogeneous values of physiological parameters of shoulder muscles and to locate sites of muscular attachment to any bone of the shoulder complex. Muscular fiber lengths, lengths of contractile element (CE), and muscle volumes were measured, corresponding physiological cross-sectional area (PCSA) were calculated, and force/length muscle relations were found. An in vivo biplanar radiography was performed on five volunteers. The photogrammetric reconstruction of bone axes and landmarks were coupled with a geometric modeling of bones and muscle sites of attachment. Muscular paths were drawn and changes in lengths during movement have been estimated. Directions of muscle forces are the same as that of muscular path at the point of attachment to bone. Magnitudes of muscular forces were found from muscle lengths coupled with force/length relations. Passive forces were directly determined contrary to active muscle forces. A resulting active muscle force is calculated from balancing weight and passive forces at each articular center. Active muscle forces were calculated by distributing the resulting force among active muscles based on the muscular PCSA values.

IMAGING CHARACTERISTIS OF MDCT IN NASOPHARYNGEAL CARCINOMA

2014 ◽  
pp. 159-167
Author(s):  
Huu Thuan Ngo ◽  
Minh Loi Hoang ◽  
Van Dinh Nguyen ◽  
Dinh Duyen Nguyen
Keyword(s):  
Nasopharyngeal Carcinoma ◽  
Lymph Nodes ◽  
Lateral Wall ◽  
Cross Sectional Study ◽  
Slice Thickness ◽  
Cross Sectional ◽  
Lymph Nodes Metastasis ◽  
Contrast Enhanced Ct ◽  
Contrast Enhanced ◽  
Key Words Nasopharyngeal Carcinoma

Objectives: Imaging characteristis of MDCT in nasopharyngeal carcinoma. Subject and methods: Cross- sectional study in 51patients with nasopharyngeal carcinoma by MDCT at Danang Cancer Hospital from January 2013 to July 2014. Results: The findings reveal that the tumor in lateral wall (66.7%), diameter > 2cm (64.7%), hypodensity (98%), contrast- enhanced CT (62.7%). Blunting of fossa of Rosenmuller (96.1%), invasion of parapharyngeal space (62.7%), destruction of pterygoid bone (19.6%), invasion of skull base (17.6%), destruction of sphenoid bone (9.8%). Lymph nodes metastasis (96.1%), diameter (> 1- 3cm) is 58.8%. T-staging by CT showed T1 (35.3%), T2 (37.3%), T3 (17.6%) and T4 (9.8%). N- staging by CT showed N2 (66.7%), N3a- N3b (19.6%). Staging of Nasopharyngeal carcinoma: stage II-III (60.8%), stage IVA-IVB (23.5%) and stage IVC (11.8%). Conclusions: MDCT with a thinner slice thickness and high quality images is able to detect lymph nodes metastasis with small size and those in deep neck area and assess comprehensively the invasion of the tumor. Key words: Nasopharyngeal carcinoma, MDCT

Study of Correctly Expanded Sonic Jet with Air Tabs

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Arun Prasad R ◽  
Thanigaiarasu S ◽  
Sembaruthi M ◽  
Rathakrishnan E
Keyword(s):  
Numerical Study ◽  
Cross Sectional ◽  
Potential Core ◽  
Convergent Nozzle ◽  
Jet Mixing ◽  
Pressure Profiles ◽  
Constant Diameter ◽  
Sonic Jet ◽  
Sectional Shape ◽  
Length Reduction

AbstractThe present numerical study is to understand the effect of air tabs located at the exit of a convergent nozzle on the spreading and mixing characteristics of correctly expanded sonic primary jet. Air tabs used in this study are two secondary jets issuing from constant diameter tubes located diametrically opposite at the periphery of the primary nozzle exit, normal to the primary jet. Two air tabs of Mach numbers 1.0 to 1.4, in steps of 0.1 are considered in this study. The mixing modification caused by air tabs are analysed by considering the mixing of uncontrolled (free) primary jet as a reference. Substantial enhancement in jet mixing is achieved with Mach 1.4 air tabs, which results in 80 % potential core length reduction. The total pressure profiles taken on the plane (YZ) normal to the primary jet axis, at various locations along the primary jet centreline revealed the modification of the jet cross sectional shape by air tabs. The stream-wise vortices and bifurcation of the primary jet caused by air tabs are found to be the mechanism behind the enhanced jet mixing.

Geometric Modeling of Ceramics Dendrites to Modulate Energy and Material Flows by Using Stereolithography

2014 ◽  
Vol 783-786 ◽  
pp. 2439-2444 ◽  
Author(s):  
Soshu Kirihara
Keyword(s):  
Computer Aided Design ◽  
Geometric Modeling ◽  
Lattice Structure ◽  
Photonic Band Gap ◽  
Ultra Violet ◽  
Terahertz Time Domain Spectroscopy ◽  
Cross Sectional ◽  
Air Atmosphere ◽  
Micro Patterning ◽  
Micro Pattern

Through computer aided design, manufacturing and evaluation, various ceramics dendrites with spatially ordered micro cavities were successfully fabricated by utilizing stereolithography. Micrometer order ceramic lattices were propagated spatially in computer graphic space. Ceramics nanoparticles were dispersed in to photo sensitive liquid resins to obtain thixotropic slurries. The paste material was spread on a grass substrate by using a mechanical knife edge, and an ultra violet micro pattern was exposed to create cross sectional solid layer. After the layer stacking process, the obtained composite precursor was dewaxed and sintered in an air atmosphere. By the micro patterning stereolithography, solid electrolyte dendrites of yttria stabilized zirconia with spatially ordered porous structures were fabricated for fuel cell miniaturizations. Gaseous fluid profiles and pressure distributions in the formed ceramic lattices with various porosity percent were visualized and analyzed by a finite element method. Subsequently, alumina micro photonic crystals with a diamond lattice structure were fabricated. Electromagnetic wave properties were measured by using a terahertz time domain spectroscopy. A complete photonic band gap was exhibited, and a localized mode to select the wavelength was obtained by introducing a defect cavity.

scholarly journals The Method of High Accuracy Calculation of Robot Trajectory for the Complex Curves

2020 ◽  
Vol 28 (4) ◽  
pp. 247-252
Author(s):  
Alexander Lozhkin ◽  
Pavol Bozek ◽  
Konstantin Maiorov
Keyword(s):  
Calculation Method ◽  
Geometric Modeling ◽  
Classical Method ◽  
Geometric Model ◽  
New Method ◽  
Approximation Methods ◽  
Linear Transformations ◽  
Design Quality ◽  
Complex Curves ◽  
Internal Properties

AbstractThe geometric model accuracy is crucial for product design. More complex surfaces are represented by the approximation methods. On the contrary, the approximation methods reduce the design quality. A new alternative calculation method is proposed. The new method can calculate both conical sections and more complex curves. The researcher is able to get an analytical solution and not a sequence of points with the destruction of the object semantics. The new method is based on permutation and other symmetries and should have an origin in the internal properties of the space. The classical method consists of finding transformation parameters for symmetrical conic profiles, however a new procedure for parameters of linear transformations determination was acquired by another method. The main steps of the new method are theoretically presented in the paper. Since a double result is obtained in most stages, the new calculation method is easy to verify. Geometric modeling in the AutoCAD environment is shown briefly. The new calculation method can be used for most complex curves and linear transformations. Theoretical and practical researches are required additionally.

scholarly journals MODELING ARCHITECTURAL FORM SURFACE DEPENDENT SECTIONS

2021 ◽  
pp. 53-58
Author(s):  
A. A. Chekalin ◽  
M. K. Reshetnikov ◽  
V. V. Shpilev ◽  
S. V. Borodulina ◽  
S. A. Ryazanov
Keyword(s):  
Geometric Modeling ◽  
Geometric Model ◽  
Residential Building ◽  
Cubic Splines ◽  
Piecewise Smooth ◽  
Additional Parameter ◽  
Mathematical Apparatus ◽  
Surface Design ◽  
Fourth Degree ◽  
Architectural Form

For the design of surfaces in architecture, as a rule, universal techniques developed for other technical industries are used. First of all, these are general kinematic surfaces and interpolation cubic splines for modeling complex piecewise smooth surfaces. The authors propose to use the fourth degree inerodifferential spline developed by them for problems of geometric modeling of architectural forms. For calculations and constructions on a computer, the proposed spline is not much more complicated than traditional cubic splines, since it has one additional parameter - a coefficient. However, this allows you to locally control the shape of a curve or surface during design, that is, to change the shape in individual areas without affecting other areas. The article proposes a method for constructing a geometric model of the kinematic surface of dependent sections with a fourth degree parabola as a generator. When using cubic splines as a guide, the surface is a 3 × 4 non-uniform (heterogeneous) spline. The article shows that the surface on the basis of the proposed mathematical apparatus can be composite piecewise-smooth. A particular case of surface design is considered on the example of creating a model of the surface of the facade of a residential building according to the existing concept. The algorithm can be easily programmed and added as a tool to existing CAD systems.

scholarly journals Geometric modeling of surfaces dependent cross sections in the tasks of spinning and laying

2019 ◽  
Vol 110 ◽  
pp. 01057
Author(s):  
Yuri Deniskin ◽  
Pavel Miroshnichenko ◽  
Andrew Smolyaninov
Keyword(s):  
Composite Materials ◽  
Cross Sections ◽  
Geometric Modeling ◽  
Geometric Model ◽  
Solid Modeling ◽  
Uniform Method ◽  
Calculation Methods ◽  
Related Process

The article is devoted to the development of a geometric model of surfaces of dependent sections to solve the problems of winding by continuous fibers in the direction of the force and its related process of automated winding of composite materials. A uniform method for specifying the surfaces of dependent sections with a curvilinear generator and a method for solid modeling of the shell obtained by winding or calculation methods are described.

Shell form in the biconvex articulate Brachiopoda: a geometric analysis

Paleobiology ◽  
1980 ◽  
Vol 6 (1) ◽  
pp. 57-76 ◽  
Author(s):  
George R. McGhee
Keyword(s):  
Geometric Model ◽  
Geometric Analysis ◽  
Small Region ◽  
Shell Morphology ◽  
Shell Surface ◽  
Absolute Size ◽  
Shell Form ◽  
Geometric Space ◽  
Biological Optimization ◽  
Area And Volume

Using a geometric model of shell morphology, it is demonstrated that biconvex brachiopods occupy only a small region of the potential geometric space available to organisms with planispiral exoskeletons composed of two articulated valves. Measurements taken for a sample of 324 genera of the articulate orders Pentamerida, Rhynchonellida, Spiriferida, and Terebratulida were analyzed using a simple geometric model of shell form and ontogeny. The frequency distribution of brachiopod shell morphologies exhibited by the four orders represents the biological optimization of the spatial relationships between area and volume. Biconvex brachiopods develop shells which are designed to minimize shell surface area while maximizing internal shell volume. The means by which optimization is achieved is related directly to the effects of increase in absolute size during ontogeny. The boundaries upon shell geometries utilizable by biconvex brachiopods are determined by (1) limitations of articulation, and (2) limitations of surface and volume.

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