Articles de revues : « Shape Analysi »

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Franceschi, Eleonora, Astrid Moser-Reischl, Mohammad A. Rahman, Stephan Pauleit, Hans Pretzsch et Thomas Rötzer. « Crown Shapes of Urban Trees-Their Dependences on Tree Species, Tree Age and Local Environment, and Effects on Ecosystem Services ». Forests 13, n^o 5 (12 mai 2022) : 748. http://dx.doi.org/10.3390/f13050748.

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Crown shapes of common European urban tree species differ from tree species to tree species and are modified by the age of a tree and its local environment. A tree’s crown shape has a great influence on the crown volume and thus on the ecosystem service provision of a tree such as the shade area or the shade density. We used the data of 3852 tree individuals from eight German cities and the crown shape data of 528 trees for the species Acer platanoides, Acer pseudoplatanus, Aesculus hippocastanum, Fraxinus excelsior, Platanus × acerifolia, Robinia pseudoacacia and Tilia cordata to analyze tree structural dimensions and the crown volume and shade dependency on a tree’s crown shapes. Ovoid (57% of all tree individuals) and spherical (24%) crown shapes were mostly observed. However, columnar shape was observed for light-demanding R. pseudoacacia in close proximity of objects. The greatest shade areas were measured for spherical shape and the highest shade density for ovoid shape. Logistic regression analysis showed significant effects of age and distance to objects on crown shapes. Significant probability of crown shapes was found for different tree species, e.g., A. hippocastanum strongly showed half-ellipsoid crown shapes.

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Bender-Heine, Adam, Michelle Russell, Allen Rickards, J. Holmes, Mark Armeni, H. Lambert et Matthew Zdilla. « Optimal Costal Cartilage Graft Selection According to Cartilage Shape : Anatomical Considerations for Rhinoplasty ». Facial Plastic Surgery 33, n^o 06 (décembre 2017) : 670–74. http://dx.doi.org/10.1055/s-0037-1607972.

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AbstractCostal cartilage grafting is a commonly used reconstruction procedure, particularly in rhinoplasty. Although costal cartilage is broadly used in reconstructive surgery, there are differing opinions regarding which costal cartilage levels provide the most ideal grafts. Grafts are typically designed to match the shape of the recipient site. The shapes of costal cartilage grafts have been described as “boat-shaped,” “C-shaped,” “canoe-shaped,” “U-shaped,” “crescent-shaped,” “L-shaped,” “semilunar,” “straight,” and “Y-shaped.” The shapes of costal cartilages are thought to lend themselves to the shapes of certain grafts; however, there has been little study of the shapes of costal cartilages, and most reports have been anecdotal. Therefore, this study is aimed to detail the average shapes of the most commonly grafted cartilages (i.e., the fifth to seventh cartilages). A total of 96 cadaveric costal cartilages were analyzed through geometric morphometric analysis. The fifth costal cartilage was determined to have the straightest shape and would therefore be particularly suitable for nasal dorsum onlay grafting. The lateral portions of the sixth and, particularly, the seventh costal cartilages have the most acute curvature. Therefore, they would lend themselves to the construction of an en bloc “L”-shaped or hockey stick-shaped nasal dorsum-columellar strut graft.

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Kumar, Pramod, Santanu Dwari, Shailendra Singh, Ashok Kumar, N. K. Agrawal et Utkarsh Kumar. « Analysis and Optimization of Conformal Patch Excited Wideband DRA of Several Shapes ». Frequenz 72, n^o 5-6 (25 avril 2018) : 197–208. http://dx.doi.org/10.1515/freq-2017-0039.

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AbstractIn this paper various shapes of DR antennas excited by common feed have been proposed and successfully implemented for wideband applications. Proposed structures are Hemispherical, Arrow-shaped and Triangular DRA, while common excited feed is inverted trapezoidal conformal patch. These shapes of DR offer significant optimization in several parameters such as impedance bandwidth, peak gain and bandwidth per unit volume of the antenna. By using inverted trapezoidal patch feed mechanism an impedance bandwidth (VSWR<2) of about 63 % for hemispherical shape, 66 % for arrow shape, and 72 % for triangular shape DRA has been achieved with maximum bandwidth per unit volume. Proposed wideband DRAs i. e. triangular, hemispherical, and arrow shapes of DR antennas cover almost complete C-band (4 GHz–8 GHz) frequency spectrum of microwave. The average peak gain within the operating band for hemispherical, arrow, and triangular shape DRA are about 5, 5.4, and 5.5 dB respectively. A comparative analysis of proposed structures for various antenna parameters has been analyzed by HFSS (High-Frequency Structure Simulator) and validated by experimental results.

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Kumar B., Varun, G. Manikandan, P. Kanna, Dawid Taler, Jan Taler, Marzena Nowak-Ocłoń, Karol Mzyk et Hoong Toh. « A Performance Evaluation of a Solar Air Heater Using Different Shaped Ribs Mounted on the Absorber Plate—A Review ». Energies 11, n^o 11 (9 novembre 2018) : 3104. http://dx.doi.org/10.3390/en11113104.

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In this paper, the effect of various shapes of ribs used in Solar Air Heaters (SAHs) was discussed. The review is concentrated on the geometry of the rib and its location on the SAH panel. Both numerical and experimental works were considered for discussion with dry air and Nano fluids as a working fluid. The influence of various shapes, such as an L shape, W shape, V shape, Multiple V shape, V shape with a gap, detachable & attachable ribs etc., was analyzed. The common fact observed from this analysis is that the implementation of artificial roughness in the absorber plate results in a considerable increase in the rate of heat transfer. Further, it is observed that ‘Multiple V-shaped with open between the ribs’ results in the maximum thermal enhancement when compared to the other shapes.

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Asha, S. K., G. Sunitha et Chandrashekhar M. Hadapad. « Different shapes of nanoparticles on peristaltic transport of a Casson fluid in the presence of MHD, thermal radiation and Porous medium ». International Journal of Computational Materials Science and Engineering 10, n^o 02 (13 mai 2021) : 2150008. http://dx.doi.org/10.1142/s2047684121500081.

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The influence of different shapes of nanoparticles on peristaltic flow of Casson fluid in an asymmetric channel is studied in this paper. The suspension of Copper oxide nanoparticles of needle, platelet and lamina shapes is taken into account. The problem is modeled in partial differential equations with suitable slip boundary conditions. The standard nonlinear equations are solved by the Homotopy Analysis Method in Mathematica Software. The influences of different shapes of nanoparticles on concentration, velocity profile and temperature profile are analyzed through the graphs. It is observed that the different shape of nanoparticles has different thermal conductivity, but the lamina shaped nanoparticles have high thermal conductivity as compared to needle and platelet shaped nanoparticles.

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Lee, Sang-ik, Jin-Yong Choi et Won Choi. « Effect of Groove Shape on Head Loss and Filtration Performance of Disc Filters ». Water 13, n^o 12 (17 juin 2021) : 1683. http://dx.doi.org/10.3390/w13121683.

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To analyze the effect of a groove cross-sectional shape on disc filters, a head loss analysis and filtration performance test were conducted using disc filters with different groove shapes (semi-elliptical- and trapezoidal-shaped grooves). Furthermore, the groove shapes were analyzed using field emission scanning electron microscopy and the relationship between flow rate and head loss was derived from the head loss test. Even if the filters were designed with the same mesh standard, the sectional areas of the grooves were different depending on the shape. Therefore, the head loss was compared under the condition that the grooves have the same sectional area by applying the relationship between head loss and sectional area, and a smaller head loss was observed in the semi-elliptical-shaped groove. Additionally, the semi-elliptical-groove-shaped disc filter was evaluated to sufficiently filter the soil particles corresponding to the 120 mesh standard. Therefore, an optimum disc filter can be designed by considering the cross-sectional shape of the disc groove to reduce energy consumption and provide stable filtration. The elliptical groove shape, which is hydraulically advantageous, is preferred for the disc filter design.

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Baechler, J., C. A. Beck et W. D. Bowen. « Dive shapes reveal temporal changes in the foraging behaviour of different age and sex classes of harbour seals (Phoca vitulina) ». Canadian Journal of Zoology 80, n^o 9 (1 septembre 2002) : 1569–77. http://dx.doi.org/10.1139/z02-150.

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Classifying dives into two-dimensional shapes based on time and depth is an attempt to extract additional information about the behaviour of aquatic air-breathing predators. In some species, there is considerable circumstantial evidence that different dive shapes represent different behaviours. However, few studies have provided direct evidence of the relationship between dive shape and function. We classified over 283 000 dives of adults (31 males and 45 females) and suckling (13) and recently weaned (15) harbour seal (Phoca vitulina) pups into seven shapes using supervised discriminant function analysis. Changes in the percentage of U-shaped dives over time within adults and weaned pups were associated with changes in food intake derived from water-flux studies on subsets of the same individuals. The changes in the percentage of U-shaped dives were accompanied by roughly reciprocal changes in V-shaped dives, whereas there was little change in other dive shapes, indicating that V-shaped dives are not generally exhibited during foraging. Video of adult males (from an animal-borne video system) also showed that there was a strong but not exclusive association between foraging and U-shaped dives. Our results indicate that changes in the percentage of U-shaped dives may serve as a reasonable index of changes in foraging behaviour. However, behaviours of suckling pups and adult males during the breeding season cannot be easily inferred from dive shape alone.

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ONISHI, Keiko, et Daisuke FUJITA. « Novel Tip Shape Reconstruction Method for Restoration of AFM Topography Images Using Nano-structures with Given Shapes ». Analytical Sciences 27, n^o 2 (2011) : 157. http://dx.doi.org/10.2116/analsci.27.157.

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Milenkovic, Jovana, Milica Vasiljevic, Nemanja Jovicic, Dragan Milovanovic, Dragica Selakovic et Gvozden Rosic. « Criteria for the Classification of the Interradicular Septum Shape in Maxillary Molars with Clinical Importance for Prosthetic-Driven Immediate Implant Placement ». Diagnostics 12, n^o 6 (10 juin 2022) : 1432. http://dx.doi.org/10.3390/diagnostics12061432.

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The aim of this study was to use cone-beam computed tomography (CBCT) to evaluate the morphometric properties of the interradicular septum (IRS) in the maxillary molar region that may be indicative for prosthetic-driven implant placement. Following the repetitive algorithm based on the visual identification of IRS shapes, we described the following IRS shapes: arrow, boat, drop, and palatal and buccal convergence. The incidence of IRS shapes showed significant differences for the first and second maxillary molars (the highest frequency for the arrow shape, and the lowest for the drop shape) with no significant difference between the molars. The most prominent width indicative for implant placement was observed in the palatal convergence shape, whereas the height criteria were the most satisfying in the buccal convergence-shaped IRS for both molars. Apart from the parameters in the coronal view, the image analysis in the axial view revealed that IRS surface area, required for the implant placement, was the most prominent in the palatal convergence shape for the first, and boat shape for the second molars. Our results showed the benefits of CBCT diagnostics in posterior maxilla morphometric analysis. IRS shape classification may be helpful in achieving more rapid and accurate planning for interventions in this region.

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BANERJEE, MOLOY K., DEBABRATA NAG, RANJAN GANGULY et AMITAVA DATTA. « HEMODYNAMICS IN STENOSED ARTERIES — EFFECTS OF STENOSIS SHAPES ». International Journal of Computational Methods 07, n^o 03 (septembre 2010) : 397–419. http://dx.doi.org/10.1142/s021987621000226x.

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A numerical analysis has been carried out to investigate the hemodynamic flow through stenosed arteries having mild (S = 25%) to severe (S = 65%) occlusions and under different regimes of flow Reynolds numbers ( Re ) ranging from 50 to 400. Influence of different stenosis shapes (rectangular, trapezoidal, cosine, and Gaussian) on key hemodynamic parameters e.g., recirculation length, wall shear stress (WSS), pressure drop, and irreversible pressure loss coefficient (C I ) are studied. It has been observed that for S = 25%, no flow separation takes place with cosine and Gaussian shaped stenoses for all the Re values considered, while for rectangular or trapezoidal shapes the flow begins to separate at Re = 400. At higher degrees of stenosis, post-stenotic recirculation is noticed for all the shapes considered — the largest recirculation length being observed with the rectangular shape. The peak centerline velocity in the stenosed region is more sensitive to a change in the degree of occlusion for rectangular stenosis than the other shapes. From the study, it is also revealed that the irreversible pressure loss coefficient (C I ) is the maximum for rectangular shaped stenosis, while it is the least for Gaussian shape. It is observed that at high Re regime, C I becomes insensitive to Re values and can be approximated to be a function of the degree of stenosis (S) and the stenosis shape only.

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Lavrova, Olga, Viktor Polevikov et Lutz Tobiska. « NUMERICAL STUDY OF THE ROSENSWEIG INSTABILITY IN A MAGNETIC FLUID SUBJECT TO DIFFUSION OF MAGNETIC PARTICLES ». Mathematical Modelling and Analysis 15, n^o 2 (20 avril 2010) : 223–33. http://dx.doi.org/10.3846/1392-6292.2010.15.223-233.

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The present study is devoted to the classical problem on stability of a magnetic fluid layer under the influence of gravity and a uniform magnetic field. A periodical peak‐shaped stable structure is formed on the fluid surface when the applied magnetic field exceeds a critical value. The mathematical model describes a single peak in the pattern assuming axial symmetry of the peak shape. The field configuration in the whole space, the magnetic particle concentration inside the fluid and the free surface structure are unknown quantities in this model. The unknown free surface is treated explicitly, using a parametric representation with respect to the arc length. The nonlinear problem is discretized by means of a finite element method for the Maxwell's equations and a finite‐difference method for the free surface equations. Numerical modelling allows to get over‐critical equilibrium free surface shapes in a wide range of applied field intensities. Our numerical results show a significant influence of the particle diffusion on the overcritical shapes.

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Karpouzian, G., G. Spedding et H. K. Cheng. « Lunate-tail swimming propulsion. Part 2. Performance analysis ». Journal of Fluid Mechanics 210 (janvier 1990) : 329–51. http://dx.doi.org/10.1017/s0022112090001318.

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The theory of an oscillating, high-aspect-ratio, lifting surface with a curved centreline (Cheng & Murillo 1984) is applied to a performance analysis of lunate-tail swimming propulsion. Thrust, power and propulsive efficiency are calculated for model lunate tails with various combinations of mode shapes and morphological features to ascertain the viability of the proportional-feathering concept, and to determine the influence of sweep and centreline curvature. One of the principal conclusions concerns the interchangeability of the heaving amplitude of the peduncle (identified with the major pitching axis) with the centreline sweep, and its effect on the propulsive efficiency, while maintaining the same thrust. Hydrodynamic reasons are also offered for the apparent preference for the crescent-moon fin shape over the V-shape at moderate sweep angles, and for the large sweep angles often found in V-shaped fins.

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Inkpen, Rob, et Kevin Hall. « Universal Shapes ? Analysis of the Shape of Antarctic Tafoni ». Geosciences 9, n^o 4 (2 avril 2019) : 154. http://dx.doi.org/10.3390/geosciences9040154.

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Using dimensional data from over 700 tafoni in Antarctica, this paper identifies how the dimensionless ratios of width/length (W/L) and depth/length (D/L) vary with tafoni length. The analysis suggests that these ratios do tend to converge to values that are similar to those found for fragments produced by brittle fracture and fragmentation. Dividing the data into quintiles and deciles, it is possible to assess how tafoni size and shape change as tafoni length increases. Smaller tafoni do tend to have a rounder plan form which rapidly changes as tafoni length increases towards the W/L ratio of 0.67. It is suggested that initial tafoni development is limited by the conditions set out in a recent mathematical model of tafoni development. This model focuses on tafoni development through the interactions of variable rock strength and the varying concentration gradient of a corrosive agent. Erosion involves the removal of relatively small sections of rock and is analogous to a continuous erosional process. This model produces tafoni of relatively circular plan form. Above a certain tafoni length it is suggested that processes associated with brittle fracture begin to dominant the development and shape of tafoni.

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Ma, Wen Yu, Jian Wei Yang, Ye Yao, Yong Qiang Zhang et Jun Zhang. « The Analysis on the Stamping Formability of High Strength Steel ». Key Engineering Materials 885 (mai 2021) : 3–9. http://dx.doi.org/10.4028/www.scientific.net/kem.885.3.

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Recently the high strength steel has been applied in the automotive more and more widely. In this study, the effect of blank shape on the formability of an automotive part was analyzed. The three kinds of blank shapes were chosen, including a rectangular shaped blank, a blank with two corners cut straightly and a blank with two corners cut in curve. The effect of the variable blank holder force on the formability was studied. The four kinds of variable blank holder force were applied. The blank shape in this part is the blank with two corners cut curve. The results show that the blank with two corners curve is the most suitable. And the blank holder force from 1000 kN to 1500 kN is the most useful for the formability.

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Gheta, Siprianus, Agustina Mei et Agnes Pendy. « EKSPLORASI KONSEP-KONSEP ETNOMATEMATIKA PADA RUMAH ADAT “KEDA NUA PU’U NIDA” DESA WATUNGGERE ». JUPIKA : JURNAL PENDIDIKAN MATEMATIKA 4, n^o 2 (28 septembre 2021) : 152–61. http://dx.doi.org/10.37478/jupika.v4i2.1191.

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The objectives of this research are 1). to find out a brief history of the Keda Nua Pu'u Nida traditional house; 2). To explore the ethnomathematical concepts contained in the Nua Pu'u Nida Traditional House. This type of research is exploratory research using an ethnographic approach with taxonomic analysis. The subjects in this study were four people and the researchers themselves. The instruments used are observation sheets, interview guidelines, and documentation. Data analysis used is a triangulation of data sources from researchers, namely by means of documentation and observation and is strengthened by reference books. The results of this study indicate the existence of geometric shapes in the traditional house of Keda Nida. The geometric shapes found are: 1) trapezoidal roof; 2) beam-shaped bearings; 3) a line-shaped roof pole; 4) the roof to the side is triangular in shape; 5) the meeting between two logs that form a corner. The shape of the parts of the traditional house can change the paradigm of students and the community under mathematics which is closely related to daily activities with culture.

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Eghwerido, Joseph Thomas. « The alpha power Teissier distribution and its applications ». Afrika Statistika 16, n^o 2 (1 avril 2021) : 2733–47. http://dx.doi.org/10.16929/as/2021.2733.181.

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Statistical distribution that represents the true characteristics of real-life data is paramount to data analysis. Thus, this study introduces a tractable alpha power Teissier distribution (APOT). Some statistical properties of the proposed model like moments, probability generating function, moment generating function and order statistic were examined. The shape of the hazard rate and survival functions were investigated. The shapes of the hazard rate function indicated increasing, decreasing, J-shaped and bathtub shapes. The results of the data analysis indicated that the APOT model performed better when compared to some existing classical statistical distributions.

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Asha, K. N., et Neetu Srivastava. « Analysis of Copper nanoparticle suspension in a stenosed non-permeable vasculature in presence of magnetic field ». Journal of Physics : Conference Series 2332, n^o 1 (1 septembre 2022) : 012012. http://dx.doi.org/10.1088/1742-6596/2332/1/012012.

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Abstract In the present article, impact of shape of Copper nanoparticle with water as base fluid on the fluid flow criteria in the congested non-permeable arteries is analyzed under the magnetic effect. Mathematically, a significant response is recorded when various shapes of nanoparticles are considered in the stenosed vasculature. To explore the effect of different shaped nanoparticles, extensive range of nanofluid volume fractions, magnetic parameters and shape factors of nanoparticle is utilized. The significant parameters are solved using analytical method as well as analyzed using the graphs. It is found that the laminar nanoparticles show finer results for flow properties like flow rate in the stenosed artery and the impedance resistance.

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Shim, H. B., et K. C. Son. « Optimal Blank Design for the Drawings of Arbitrary Shapes by the Sensitivity Method ». Journal of Engineering Materials and Technology 123, n^o 4 (24 juillet 2000) : 468–75. http://dx.doi.org/10.1115/1.1398082.

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The sensitivity method is employed in this work in order to find initial blank shapes which result in desired shapes after deformation. By assuming the final deformation shape be the drawn cup with uniform trimming allowance at the flange, the corresponding initial blank which gives the desired final shape after deformation has been found. With the aid of a well-known dynamic explicit analysis code PAM-STAMP, shape sensitivity has been obtained. To get the shape sensitivity numerically, a couple of deformation processes have been analyzed. Drawings of trapezoidal cup, oil pan, and Audi front door panel, the benchmark test problem of Numisheet ’99, have been chosen as the examples. In every case the optimal blank shape has been obtained after only a few modifications without a predetermined deformation path. With the predicted optimal blank, both computer simulation and experiment are performed. Excellent agreements are obtained between simulation and experiment in every case. Through this investigation, the sensitivity method is found to be very effective in the design of arbitrary shaped drawing processes.

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CHANG, CHIN-CHEN, YAW-WEN CHEN et DANIEL JAMES BUEHRER. « A TWO-DIMENSIONAL SHAPE RECOGNITION SCHEME BASED ON PRINCIPAL COMPONENT ANALYSIS ». International Journal of Pattern Recognition and Artificial Intelligence 08, n^o 04 (août 1994) : 859–75. http://dx.doi.org/10.1142/s0218001494000449.

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In this paper, we propose a simple, but efficient method to recognize two-dimensional shapes without regard to their translation, rotation, and scaling factors. In our scheme, we use all of the boundary points to calculate the first principal component, which is the first shape feature. Next, by dividing the boundary points into groups by projecting them onto the first principal component, each shape is partitioned into several blocks. These blocks are processed separately to produce the remaining shape features. In shape matching, we compare two shapes by calculating the difference between the two sets of features to see whether the two shapes are similar or not. The amount of storage used to represent a shape in our method is fixed, unlike most other shape recognition schemes. The time complexity of our shape matching algorithm is also O(n), where n is the number of blocks. Therefore, the matching algorithm takes little computation time, and is independent of translation, rotation, and scaling of shapes.

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Davidson, M. « Special relativity and the intrinsicality of shape ». Analysis 74, n^o 1 (15 décembre 2013) : 57–58. http://dx.doi.org/10.1093/analys/ant100.

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Jalaal, Maziyar, Dave Kemper et Detlef Lohse. « Viscoplastic water entry ». Journal of Fluid Mechanics 864 (11 février 2019) : 596–613. http://dx.doi.org/10.1017/jfm.2019.32.

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The impact of viscoplastic droplets on a free surface of water is studied. The droplet undergoes an elasto-plastic deformation at the early stages of water entry. At large time, the yield stress dominates; therefore, the droplet solidifies and reaches an equilibrium shape. Depending on the impact velocity and the rheology of the droplet, the final morphologies vary from pear-shaped to capsules that contain bubbles. We perform an analysis of the orders of magnitude of the forces and introduce the relevant dimensionless groups. Furthermore, we categorize the final shapes in a phase diagram and analyse their geometrical properties. The process presents a method of making non-spherical beads and capsules with tunable shapes and provides information on the general problem of the impact of highly deformable objects on a liquid surface.

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Li, Peng, Brian Corner et Steven Paquette. « Shape analysis of female torsos based on discrete cosine transform ». International Journal of Clothing Science and Technology 27, n^o 5 (7 septembre 2015) : 677–91. http://dx.doi.org/10.1108/ijcst-03-2014-0035.

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Purpose – The purpose of this paper is to present results of shape analysis of female torso shape using the discrete cosine transform (DCT) from a three-dimensional (3D) whole body scan database. Design/methodology/approach – Torso shape is a central part of body shape and difficult to describe by linear measurements. In order to analyze body shape variation within a population the authors employed a DCT-based shape description method to compresses a dense 3D body scan surface into a small vector that preserves shape and removes size. The DCT-based shape descriptors of torso surfaces are further fed to principal component analysis (PCA) that decompose shape variation into constituent shape components. A visualization program was developed to observe principal components of torso shape and interpret their meanings. Findings – Extreme shapes of the first ten principal components summarize major shape variations and identify shapes that are difficult to capture with traditional anthropometric measurements. PCA results also help to find and retrieve similar shapes from a population-level database. Originality/value – Using the DCT for PCA of torso shape is a unique and original approach. It provides a basis for the description and classification of torso shape in 3D and the results from the shape analysis are potentially useful for designers of clothing and personal protective equipment.

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Attard, Marie R. G., Emma Sherratt, Paul McDonald, Iain Young, Marta Vidal-García et Stephen Wroe. « A new, three-dimensional geometric morphometric approach to assess egg shape ». PeerJ 6 (27 juin 2018) : e5052. http://dx.doi.org/10.7717/peerj.5052.

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This paper proposes a new methodology to quantify patterns of egg shape variation using geometric morphometrics of three-dimensional landmarks captured on digitally reconstructed eggshells and demonstrates its performance in capturing shape variation at multiple biological levels. This methodology offers unique benefits to complement established linear measurement or two-dimensional (2D) contour profiling techniques by (i) providing a more precise representation of eggshell curvature by accounting for variation across the entire surface of the egg; (ii) avoids the occurrence of correlations from combining multiple egg shape features; (iii) avoids error stemming from projecting a highly-curved three-dimensional (3D) object into 2D space; and (iv) enables integration into 3D workflows such as finite elements analysis. To demonstrate, we quantify patterns of egg shape variation and estimate morphological disparity at multiple biological levels, within and between clutches and among species of four passerine species of different lineages, using volumetric dataset obtained from micro computed tomography. The results indicate that species broadly have differently shaped eggs, but with extensive within-species variation so that all four-focal species occupy a range of shapes. Within-species variation is attributed to between-clutch differences in egg shape; within-clutch variation is surprisingly substantial. Recent comparative analyses that aim to explain shape variation among avian taxa have largely ignored potential biases due to within-species variation, or use methods limited to a narrow range of egg shapes. Through our approach, we suggest that there is appreciable variation in egg shape across clutches and that this variation needs to be accounted for in future research. The approach developed in this study to assess variation in shape is freely accessible and can be applied to any spherical-to-conical shaped object, including eggs of non-avian dinosaurs and reptiles through to other extant taxa such as poultry.

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Covantev, Serghei, Rasul Uzdenov, Daria Turovets et Olga Belic. « Spleen : an organ of multiple shapes ». Iberoamerican Journal of Medicine 3, n^o 4 (5 octobre 2021) : 326–31. http://dx.doi.org/10.53986/ibjm.2021.0052.

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Introduction: The spleen is located in the upper part of the abdominal cavity. As an organ, the spleen can have various shapes and size. Material and methods: The human spleen was studied in 273 cadavers (154 men and 119 women) who did not have diseases of the spleen. The shape of the spleen was analyzed based on splenic index, Michels classification. Results: The most common shape of the spleen in men is the elongated one. It was encountered in 79 (51.3%) cases out of 154. In women, the most common shape was the intermediate. It was encountered in 51 (42.9%) of the 119 cases. Based on Michels classification the clinoid (wedge) shape was encountered in 102 (37.74%) cases, triangular in 59 (21.83%) and tetrahedral in 30 (11.1%). In 30.26% the shape of the spleen couldn’t be classified according to Michels classification. In 21 cases (7.77%) the spleen had a flat shape; in 27 (9.99%) – dome-shaped; in 1 case (0,37%) – Z-shape; in 18 (6.66%) – round shape; in 6 (2.22%) – irregular shape; in 2 (0.66%) - shape with a node in the hilum; in 1 (0,37%) – rhomboid shape, in 2 (0,74%) – bilobed shape and in 4 cases (1,48%) – lobular shape. The splenic fissures located on the upper edge of the organ were found in 81 (29.91%) cases, and also on the lower edge - in 41 (14.02%) cases. In 13 (4.67%) cases fissures were encountered on both sides. In 148 (51.4%) cases the spleen had no fissures on its surface. Conclusions: The spleen has various shapes beyond the classical wedge, triangular and tetrahedral. All of these shapes do not represent a pathological finding but in certain situation may require further analysis and interpretation depending on the imaging technique and experience of the physician.

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Kim, Soyeon, Dai-Soon Kwak et In-Beom Kim. « Morphometric Analysis and Classification of the Cross-Sectional Shape of the C2 Lamina ». BioMed Research International 2017 (2017) : 1–7. http://dx.doi.org/10.1155/2017/7276946.

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A thorough understanding of the morphology of the lamina of the second cervical vertebra (C2) is important for safe C2 translaminar screw placement. Although anatomical characteristics of the C2 lamina have been widely documented, individual differences in morphology have not been addressed. The aim of this study was to morphometrically analyze the cross-sectional shape of the C2 lamina and classify the shape to describe individual differences. Morphometric analysis was conducted on 145 three-dimensional C2 models based on computerized tomography images from Korean adult cadavers. Several parameters were measured on a cross-section image of the lamina model. Based on numerical criteria, all of the C2 lamina’s cross-sectional shapes could be categorized into three distinctive morphological types: pyriform, ellipse, and obpyriform shapes. We confirmed that most Koreans can accommodate C2 translaminar screw placement with a lower limit of the 95% confidence interval of thickness measured at 6.26 mm. Morphometric analysis suggested that the obpyriform-shaped lamina (4.48%) is likely to require screw trajectory adjustment to avoid cortical breakout of the screw. Our results will enhance current anatomical understanding of the C2 lamina and thus facilitate safer C2 translaminar screw placement.

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Kim, Young-Chan, Seyed Javad Mortazavi, Alireza Farzampour, Jong-Wan Hu, Iman Mansouri et Paul Oluwaseun Awoyera. « Optimization of the Curved Metal Damper to Improve Structural Energy Dissipation Capacity ». Buildings 12, n^o 1 (11 janvier 2022) : 67. http://dx.doi.org/10.3390/buildings12010067.

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Structural curved metal dampers are implemented in various applications to mitigate the damages at a specific area efficiently. A stable and saturated hysteretic behavior for the in-plane direction is dependent on the shape of a curved-shaped damper. However, it has been experimentally shown that the hysteretic behavior in the conventional curved-shaped damper is unstable, mainly as a result of bi-directional deformations. Therefore, it is necessary to conduct shape optimization for curved dampers to enhance their hysteretic behavior and energy dissipation capability. In this study, the finite element (FE) model built in ABAQUS, is utilized to obtain optimal shape for the curved-shaped damper. The effectiveness of the model is checked by comparisons of the FE model and experimental results. The parameters for the optimization include the curved length and shape of the damper, and the improved approach is conducted by investigating the curved sections. In addition, the design parameters are represented by B-spline curves (to ensure enhanced system performance), regression analysis is implemented to derive optimization formulations considering energy dissipation, constitutive material model, and cumulative plastic strain. Results determine that the energy dissipation capacity of the curved steel damper could be improved by 32% using shape optimization techniques compared to the conventional dampers. Ultimately, the study proposes simple optimal shapes for further implementations in practical designs.

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Klassen, E., A. Srivastava, W. Mio et S. H. Joshi. « Analysis of planar shapes using geodesic paths on shape spaces ». IEEE Transactions on Pattern Analysis and Machine Intelligence 26, n^o 3 (mars 2004) : 372–83. http://dx.doi.org/10.1109/tpami.2004.1262333.

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Rahbar-Ranji, Ahmad. « Modal analysis of a box-shape girder by numerical method ». Odes’kyi Politechnichnyi Universytet. Pratsi, n^o 2 (20 août 2016) : 21–25. http://dx.doi.org/10.15276/opu.2.49.2016.06.

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Ivasenko, I. B., O. R. Berehulyak et R. A. Vorobel. « Analysis of dimple shape on fractographic heat-resistant steel images ». Information extraction and processing 2018, n^o 46 (27 décembre 2018) : 34–37. http://dx.doi.org/10.15407/vidbir2018.46.034.

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Chermant, Jean-Louis, et Michel Coster. « Analyse de la forme. / Shape analysis ». Sciences Géologiques. Bulletin 46, n^o 1 (1993) : 45–78. http://dx.doi.org/10.3406/sgeol.1993.1897.

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Milanovic, Pavle, Dragica Selakovic, Milica Vasiljevic, Nemanja U. Jovicic, Dragan Milovanović, Miroslav Vasovic et Gvozden Rosic. « Morphological Characteristics of the Nasopalatine Canal and the Relationship with the Anterior Maxillary Bone—A Cone Beam Computed Tomography Study ». Diagnostics 11, n^o 5 (20 mai 2021) : 915. http://dx.doi.org/10.3390/diagnostics11050915.

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The aim of this study was to evaluate the interconnection between the type of nasopalatine canal (NPC) and morphometric characteristics of the anterior maxilla. The investigation involved 113 subjects, and the morphometric parameters were obtained using cone beam computed tomography (CBCT). NPC shapes were classified into four types: banana-, hourglass-, cylindrical-, and funnel-shaped (distribution of approximately 9, 25, 31, and 35%, respectively). The analysis revealed that the NPC shape was significantly connected with the morphometric properties of anterior maxilla horizontal dimensions. In general, a banana-shaped NPC was accompanied with an overall reduction in anterior maxilla diameters when compared to other NPC shapes, with no significant difference between the other three NPC shapes. Furthermore, the morphometric characteristics that depend on NPC shape at the sagittal cross-section were significantly correlated with diameters of the incisive foramen, nasal foramen, and NPC length. According to the results of our study, it seems that the presented analyses of morphometric data may allow useful insight into the algorithms of various interconnections between the measures obtained in the region of the anterior maxilla, which could be of interest for a time rationale approach when planning some surgical procedures, such as immediate dental implant placement planning.

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De Sanctis, Angela, et Stefano Antonio Gattone. « Information Geometry Tools for Shape Analysis ». Nonlinear Phenomena in Complex Systems 23, n^o 2 (9 juillet 2020) : 243–50. http://dx.doi.org/10.33581/1561-4085-2020-23-2-243-250.

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In this work, the use of Information Geometry tools in Shape Analysis is investigated. Landmarks of complex shapes are represented as probability distributions in a statistical manifold where geodesics with respect to different Riemannian metrics could be defined. Geodesics are considered both for studying the shape evolution in time and for deriving shape distances to be used in shape clustering.

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Micheas, Athanasios C., et Dipak K. Dey. « Modeling shape distributions and inferences for assessing differences in shapes ». Journal of Multivariate Analysis 92, n^o 2 (février 2005) : 257–80. http://dx.doi.org/10.1016/j.jmva.2003.09.013.

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Wondo, Trisna, Maria Fatima Mei et Finsensius Y. Naja. « Exploration of geometry Symbol in Traditional Houses of the Lio District of Ende for Geometry Learning ». Jurnal Pendidikan dan Kebudayaan Missio 12, n^o 1 (30 janvier 2020) : 32–44. http://dx.doi.org/10.36928/jpkm.v12i1.71.

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This study aims to describe the symbols and geometry that exist in the traditional house of the Lio tribe of Wolokoli Village, Wolowaru District, Ende Regency in ethnomathematics perspective in terms of mathematical concepts. This type of research is qualitative research with an ethnographic approach. The subjects of this study consisted of several informants (chiefs, village heads, teachers and students). Using observation and interview techniques, and using qualitative descriptive analysis. The results showed the existence of symbol shapes and geometry in the building of traditional houses of the Lio tribe of Wolokoli Village, Wolowaru District, Ende Regency. Other symbolic forms include leke (foundation pillars made of stone and wood), there are twenty oval-shaped stone pillars and one rectangular wooden pole, Tenga (lante beam) in the form of a tube. Dalo is rectangular in shape. Rectangular lure. Wisu (four main pillars) shaped beam. Kebi (wall) is rectangular in shape. Mangu (nok pole) shaped beam. Block shaped jara. Pene / Pere is rectangular in shape. Eba beams. Lara is a block. Hubu (roof) is made of trapezoid-shaped reeds. Form symbols and geometrical structures that exist in the traditional Lio Tribe of Wolokoli Village, namely lines, angles, squares, rectangles, triangles, trapezoid, parallelogram, triangles, hexagons, beams, tubes, and triangular prisms. The shape in these parts of the house can change the paradigm of children and society that mathematics has a relationship with daily activities and relationships with culture and can be learned in a fun way in solving problems of learning geometry material.

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Liu, Yang, Chun Ting Yang et Jing Yu. « A Novel Method for Body Shape Analysis in E-MTM ». Applied Mechanics and Materials 20-23 (janvier 2010) : 1482–86. http://dx.doi.org/10.4028/www.scientific.net/amm.20-23.1482.

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Body shape analysis module is an important part in the e- Measure to Made. In this article, we discuss the body shape analysis approach based on fuzzy particle swarm optimization clustering algorithm.First we extract parameters features of the body shapes in body shape database which obtained from 3D scanner. Then fuzzy particle swarm optimization clustering algorithm is implemented to classify these body shapes and the clustering results are obtained.The results show it’s a effective method.

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Lu, Jinming, et Ewald A. Werner. « Cathode Shape Design for Steady-State Electrochemical Machining ». Algorithms 16, n^o 2 (19 janvier 2023) : 67. http://dx.doi.org/10.3390/a16020067.

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The inverse or cathode shape design problem of electrochemical machining (ECM) deals with the computation of the shape of the tool cathode required for producing a workpiece anode of a desired shape. This work applied the complex variable method and the continuous adjoint-based shape optimization method to solve the steady-state cathode shape design problem with anode shapes of different smoothnesses. An exact solution to the cathode shape design problem is proven to exist only in cases when the function describing the anode shape is analytic. The solution’s physical realizability is shown to depend on the aspect ratio of features on the anode surface and the width of the standard equilibrium front gap. In cases where an exact and physically realizable cathode shape exists, the continuous adjoint-based shape optimization method is shown to produce accurate numerical solutions; otherwise, the method produces cathode shapes with singularities. For the latter cases, the work demonstrates how perimeter regularization can be applied to compute smooth approximate cathode shapes suitable for producing workpieces within the range of manufacturing tolerance.

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Grande-del-Arco, Jessica, Ricardo Becerro-de-Bengoa-Vallejo, Patricia Palomo-López, Daniel López-López, César Calvo-Lobo, Eduardo Pérez-Boal, Marta Elena Losa-Iglesias, Carlos Martin-Villa et David Rodriguez-Sanz. « Radiographic Analysis on the Distortion of the Anatomy of First Metatarsal Head in Dorsoplantar Projection ». Diagnostics 10, n^o 8 (2 août 2020) : 552. http://dx.doi.org/10.3390/diagnostics10080552.

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Background: The diagnostic of flat and crest-shaped of first metatarsal heads has been associated as an important risk factor for hallux deformities, such as hallux valgus and hallux rigidus. The rounded form of the first metatarsal head on the dorsoplantar radiograph of the foot has been believed to be associated with the development of hallux valgus. Purpose: The aim of this study was to clarify the effect of tube angulation on the distortion of first metatarsal head shape, and verify the real shape of the metatarsal head in anatomical dissection after an X-ray has been taken. Materials and Methods: In this prospective study at Universidad Complutense de Madrid, from December 2016 to June 2019, 103 feet from embalmed cadavers were included. We performed dorsoplantar radiograph tube angulation from 0° until 30° every 5° on all specimens; then, two observers verified the shape of the first metatarsal head in the radiographs and after its anatomic dissection. Kappa statistics and McNemar Bowker tests were used to assess and test for intra and interobserver agreement of metatarsal shape. Results: We calculated the intraobserver agreement, and the results showed that the first metatarsal head is distorted and crested only when the angle of the X-ray beam is at 20° of inclination (p < 0.001). The interobserver agreement showed good agreement at 0°, 5°, 10°, 20°, and 25° and was excellent at 30° (p < 0.001). Conclusion: All of the studies that we identified in the literature state that there are three types of shapes of the first metatarsal head and relate each type of head to the diagnosis of a foot pathology, such as hallux valgus or hallux rigidus. This study demonstrates that there is only the round-shaped form, and not three types of metatarsal head shape. Therefore, no diagnoses related to the shape of the first metatarsal head can be made.

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Zhang, Enhui, et Ren He. « Numerical analysis on the sloshing of free oil liquid surface based on fuel tanks of different shapes ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 234, n^o 18 (8 avril 2020) : 3584–99. http://dx.doi.org/10.1177/0954406220916483.

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The shape of fuel tank is one of the main factors influencing oil liquid sloshing in fuel tank without baffles. The change of oil liquid sloshing pressure and free oil liquid surface area in fuel tanks of different shapes is the focus of this study. First, the reliability of the simulation method is verified by the test. Second, three different shapes of fuel tanks, which are rectangle, ellipse, and triangle, are proposed, and each shape of fuel tank is improved. A series of simulations are carried out under the same condition. The related history curves of oil liquid sloshing pressure and free oil liquid surface area are obtained, and the pressure contours of oil liquid sloshing and position diagrams of free oil liquid surface are displayed in the process of oil liquid sloshing. Finally, simulation data are compared and analyzed. In three different shapes of fuel tanks, it is found that the pressure of oil liquid sloshing in elliptical fuel tank is the biggest and time-area value of free oil liquid surface area in triangular fuel tank is the smallest. The curved bottom wall of fuel tank is beneficial to reduce the pressure amplitude of oil liquid sloshing and time-area value. All things considered, the heart-shaped fuel tank is optimal for reducing the pressure amplitude of oil liquid sloshing and evaporative emission under the same condition.

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Duplij, Steven. « Arity Shape of Polyadic Algebraic Structures ». Zurnal matematiceskoj fiziki, analiza, geometrii 15, n^o 1 (25 mars 2019) : 3–56. http://dx.doi.org/10.15407/mag15.01.003.

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Radvilaitė, Urtė, Álvaro Ramírez-Gómez, Arūnas Jaras, Rimantas Kačianauskas et Dainius Rusakevičius. « LOW-RESOLUTION SPHERICAL HARMONICS MODELS IN APPLICATION TO QUASI-QUADRIC PARTICLE SHAPES ». Engineering Structures and Technologies 8, n^o 4 (16 décembre 2016) : 131–42. http://dx.doi.org/10.3846/2029882x.2016.1268073.

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In this paper a numerical analysis was performed developing low-resolution spherical harmonics (LRSH) models in order to describe particle shapes. The potential of LRSH, limited by the expansion degree L ≤ 3, to describe quasi-regular particle shapes was explored. The term “quasi” is used hereafter to indicate the monomeric, almost regular shaped, particle described by a single continuous function. This approach reflects the shape of a major part of soil minerals. It was shown, that even the simplest case of the suggested low-resolution harmonics technique with L = 1 showed sufficient accuracy. The main drawback of the suggested approach was that the low-resolution harmonics yield particle shapes with nearly sharp angles, there-fore, enhanced analysis of local surface curvatures becomes necessary. An application using quasi-ellipsoidal particles is enclosed.

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Fairley, Neal, Pascal Bargiela, Adam Roberts, Vincent Fernandez et Jonas Baltrusaitis. « Practical guide to understanding goodness-of-fit metrics used in chemical state modeling of x-ray photoelectron spectroscopy data by synthetic line shapes using nylon as an example ». Journal of Vacuum Science & ; Technology A 41, n^o 1 (janvier 2023) : 013203. http://dx.doi.org/10.1116/6.0002196.

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Chemical state analysis of a sample surface through fitting bell-shaped curves to x-ray photoelectron spectroscopic polymer data is reviewed using nylon to introduce and discuss aspects of data analysis. Different strategies for modeling chemistry in nylon spectra are presented and in so doing, a case is made to include in published science the design logic and implementation in terms of line shapes and optimization parameter constraints between components in a peak model. Imperfections in line shape relative to the true shape for photoemission lines, when compensated for using constraints to optimization parameters, are shown to provide chemical state information about a sample that justify, for peak models constructed with these limitations, metrics for goodness-of-fit different from those expected for pulse-counted data.

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Kráľ, Ján, et Ján Kráľ. « Verification of Manufacturing Accuracy of Mathematically Defined Shaped Surfaces on 3D CNC Milling Machine ». Key Engineering Materials 581 (octobre 2013) : 423–30. http://dx.doi.org/10.4028/www.scientific.net/kem.581.423.

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Verification of programming of various control systems and production of mathematically defined shaped surfaces on 3D CNC milling machine is a challenging technological process. Appropriate design and optimization of tool path is essential for the production of high-quality surfaces with the required accuracy and roughness. This paper presents the design of shaped surfaces in various programming means in order to evaluate both the accuracy of the shape manufactured by the production machine and also by program created shapes for control systems of 3D milling machines. Based on the analysis of mathematically defined shaped surfaces to evaluate both accuracy of shape of 3D milling machine and also applied programs for the programming of the selected control system the shaped surface "Interface" was chosen. The advantage of mathematically described surface is a better way to evaluate the accuracy compare to surface modeled e.g. by Bezier ́s curves. Mathematically described surfaces enable us to optimize their shapes by available mathematical functions. Typical example the derivatives are, which make it possible to search extremes. Verification of the shaped surfaces accuracy according to created control programs was solved using the 3D Carl-Zeiss coordinate system and also HOLOS software. Verified programs for the NC machine programming were in CATIA V5, Pro/Engineer and EqCAM. The result is an optimally designed original EqCAM program for 3D CNC milling machine programming, which generates optimal NC codes and bypasses various built-in interpolations, and by precise control at every step it is possible to achieve maximum accuracy and quality of machined surface for each 3D CNC milling machine.

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Wang, Hao, et E. S. Takle. « Model-Simulated Influences of Shelterbelt Shape on Wind-Sheltering Efficiency ». Journal of Applied Meteorology 36, n^o 6 (1 juin 1997) : 695–704. http://dx.doi.org/10.1175/1520-0450-36.6.695.

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Abstract The authors report results of a numerical model used to simulate wind and turbulence fields for porous, living shelterbelts with seven different cross-sectional shapes. The simulations are consistent with results of Woodruff and Zingg whose wind-tunnel study demonstrated that all shelterbelts with very different shapes have nearly identical reduction of wind and turbulence. The simulations also showed that the pressure-loss (resistance) coefficient for smooth-shaped or streamlined shelterbelts is significantly smaller than that for rectangle-shaped or triangle-shaped shelterbelts with a windward vertical side. However, the shelter effects are not proportional to the pressure-loss coefficient (drag). Analysis of the momentum budget demonstrated that in the near lee and in the far lee, both vertical advection and pressure gradient have opposite roles in the recovery of wind speed. This behavior, combined with differences in permeability, is the likely cause of reduced sensitivity of shelter effects to shelterbelt shape.

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Tasker, Lorna H., Nigel G. Shapcott, Alan J. Watkins et Paul M. Holland. « The effect of seat shape on the risk of pressure ulcers using discomfort and interface pressure measurements ». Prosthetics and Orthotics International 38, n^o 1 (17 mai 2013) : 46–53. http://dx.doi.org/10.1177/0309364613486918.

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Background: It is clinically known that shape is important when selecting or designing a wheelchair support surface for the prevention of pressure ulcers (a £2 billion annual cost to the National Health Service, UK); however, the effect of different levels of shape contouring has not been adequately studied. Objectives: To investigate the effect of seat shape on the risk of pressure ulcers using discomfort and interface pressure measurements. Study design: Randomised, repeated trial. Methods: Thirty able-bodied participants sat with restricted movement for 30 min in three sessions to evaluate two cushion shapes against a flat baseline surface. Visual Analog Scaling and pressure mapping were used to measure surrogates for pressure ulcer risk, discomfort and interface pressures, respectively. Results: Linear regression revealed a reduction in discomfort ( p < 0.05) on the custom contoured shapes. Interface pressures measured were also lower ( p < 0.05) on the custom contoured shapes, and a negative Pearson’s correlation ( p < 0.05) indicated an association between smaller hip widths and increased discomfort for the commercially shaped cushion. Conclusions: The results of this study confirm that custom contoured shapes were effective at reducing pressure ulcer surrogate measures in the participants of this study and therefore suggests that the contribution of a cushion’s three-dimensional contours on pressure ulcer risk should be further researched. Clinical relevance The measurement of seat shape, discomfort and interface pressure in surrogate participants can help inform the design of wheelchair seating for individuals who are insensate or otherwise at risk of developing pressure ulcers. This knowledge can now be implemented using modern three-dimensional shape acquisition, analysis and fabrication technologies.

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Noh, Eun Sun, Sergio E. Ulloa et Hyuck Mo Lee. « The Effect of the Geometrical Shape and Size of the Cross Section on the Spin-Polarized Transport and the Giant Magnetoresistance : Finite Element Method Analysis ». Solid State Phenomena 124-126 (juin 2007) : 843–46. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.843.

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We analyze the effect of the geometrical shape and size of the cross section on the spin-polarized transport and the giant magnetoresistance (GMR) by a finite element method, and evaluate the stability and the physical properties of nano-scale spin valves. We calculate the transmission coefficients in the ballistic regime by using a transfer-matrix method, and evaluate the GMR of the current perpendicular to the plane (CPP) by using a circuit theory. The conduction-band structure is simplified to the potential step, which is determined by combining the interfacial parameters calculated by first-principles with the free electron model. The geometrical shapes of the cross section are line and square. As a result, the cross sectional shape has a significant effect on the spin-polarized transport and the GMR. The square-shaped cross section has an advantage of the large GMR, which is contrary to the line-shaped cross section. These phenomena result from the difference of the cut-off energies with the transverse modes and, consequently, the different spin-down transmission coefficients.

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Mele, A. R. « Synchronic self-control revisited : Frog and Toad shape up ». Analysis 58, n^o 4 (1 octobre 1998) : 305–10. http://dx.doi.org/10.1093/analys/58.4.305.

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Xu, Lei, Rui Peng Guo, Jia Feng Lei et Rui Yang. « Densification Process and Properties of Powder Metallurgy Ti-5Al-2.5Sn Alloy ». Applied Mechanics and Materials 552 (juin 2014) : 278–82. http://dx.doi.org/10.4028/www.scientific.net/amm.552.278.

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Net shape process from pre-alloyed powder has become a viable approach to manufacture high-performance, complex shaped titanium alloy components. In this work densification of Ti-5Al-2.5Sn powder compacts in mild steel containers by means of hot isostatic pressing was studied. Due to the shielding effect of the container, inhomogeneous deformation of Ti-5Al-2.5Sn powder compacts was observed during the experiment and this was also predicted by a finite element analysis. The mechanical properties of powder metallurgy (PM) Ti-5Al-2.5Sn alloy of different density were compared. Near-net-shape forming processes of PM titanium alloy parts are studied. By using metal capsules and metal internal tooling, near-net-shaping of PM parts with complex shapes was demonstrated. The design of capsules and tooling was found very important because of the different shrinkage ratio of the differently shaped regions of the component.

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Bocharova, E. N., P. V. Chistyakov et R. K. Zhdanov. « Using 3D Scanning to Study Composite Slotted Tools from the Early Holocene of Eastern Siberia (the Case of Kazachka-1 Site) ». Problems of Archaeology, Ethnography, Anthropology of Siberia and Neighboring Territories 27 (2021) : 57–65. http://dx.doi.org/10.17746/2658-6193.2021.27.0057-0065.

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The article demonstrates the potential applications of 3D scanning of composite slotted tools and the use of models as a basis for further scientific research. The scanning was carried out with high-precision equipment (Solutionix D700 scanner). The scanner provides high precision data acquisition of the geometry and surface of an artefact. As examples of archaeological artefacts we used composite slotted tools from the site of Kazachka-I. There were two bone tools from cultural layers 19 and 11. As a result of three-dimensional scanning application, a series of high-resolution scaled models was created. The series of cross-sections and metric measurements were made on the obtained models with the use of special software. Through analysis of cross-sectional shapes and comparison with experimental modelling data, conclusions on the basic process steps in slotted tools manufacture have been drawn. V-, U- and W-shaped cross-sections have been identified. Slots of bone tool from layer 19 has V- and U-shaped cross-sections. Slots of bone tool from layer 11 have U- and W-shaped cross-sections. The variety of cross-sectional shapes may indicate different techniques in the manufacture of the slots. The U-shaped cross-section may have been created by cutting the slot with a stone tool, the edge of which has been broken in the process. The W-shape may indicate that the direction of motion of the tool in this section was changed during operation. The V-shape was obtained by using a sharp tool throughout the slotting process. These conclusions are preliminary and need to be verified by a series of experiments and use-wear analysis.

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Shingaki, Ryuji, Yasuhiro Kasahara, Megumi Iwano, Masayoshi Kuwano, Tomomasa Takatsuka, Tetsuyoshi Inoue, Susumu Kokeguchi et Kazuhiro Fukui. « Induction of L-form-like cell shape change of Bacillus subtilis under microculture conditions ». Microbiology 149, n^o 9 (1 septembre 2003) : 2501–11. http://dx.doi.org/10.1099/mic.0.26259-0.

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A remarkable cell shape change was observed in Bacillus subtilis strain 168 under microculture conditions on CI agar medium (Spizizen's minimal medium supplemented with a trace amount of yeast extract and Casamino acids). Cells cultured under a cover glass changed in form from rod-shaped to spherical, large and irregular shapes that closely resembled L-form cells. The cell shape change was observed only with CI medium, not with Spizizen's minimum medium alone or other rich media. The whole-cell protein profile of cells grown under cover glass and cells grown on CI agar plates differed in several respects. Tandem mass analysis of nine gel bands which differed in protein expression between the two conditions showed that proteins related to nitrate respiration and fermentation were expressed in the shape-changed cells grown under cover glass. The cell shape change of CI cultures was repressed when excess KNO3 was added to the medium. Whole-cell protein analysis of the normal rod-shaped cells grown with 0·1 % KNO3 and the shape-changed cells grown without KNO3 revealed that the expression of the branched-chain α-keto acid dehydrogenase complex (coded by the bfmB gene locus) was elevated in the shape-changed cells. Inactivation of the bfmB locus resulted in the repression of cell shape change, and cells in which bfmB expression was induced by IPTG did show changes in shape. Transmission electron microscopy of ultrathin sections demonstrated that the shape-changed cells had thin walls, and plasmolysis of cells fixed with a solution including 0·1 M sucrose was observed. Clarifying the mechanism of thinning of the cell wall may lead to the development of a new type of cell wall biosynthetic inhibitor.

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Yang, Yeong-Bin, et Jae-Hoon Kang. « Comparisons of Paraboloidal Shells and Sinusoidal-Shaped Shells in Natural Frequencies ». Volume 24, No 3, September 2019 24, n^o 3 (septembre 2019) : 451–57. http://dx.doi.org/10.20855/ijav.2019.24.312.

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Natural frequencies and mode shapes are obtained for a sinusoidal-shaped shell of revolution by using the Ritz method from a three-dimensional (3-D) analysis instead of a mathematically two-dimensional (2-D) thin shell theory or high order thick shell theory. The present analysis uses circular cylindrical coordinates instead of 3-D shell coordinates, which have been used in traditional shell analyses. Convergence studies can analyze the first five frequencies to four-digit exactitude. Results are given for a variety of shallow and deep sinusoidal-shaped shells with different boundary conditions. The sinusoidal-shaped shells are very similar to paraboloidal shells in shape. The frequencies of the sinusoidal-shaped shells from the present 3-D method are compared with those from 2-D thin shell theories for paraboloidal shells. The present 3-D method is applicable to very thick as well as thin shells.

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