The Influence of Foot Abduction on Differences between Two-Dimensional and Three-Dimensional Rearfoot Motion

1998 ◽  
Vol 19 (1) ◽  
pp. 26-31 ◽  
Author(s):  
Irene McClay ◽  
Kurt Manal
Keyword(s):  
Dimensional Analysis ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Dimensional Approach ◽  
Foot Placement ◽  
Time To Peak ◽  
The Past ◽  
Study Results ◽  
Recreational Runners ◽  
Rearfoot Motion

The advantage of a three-dimensional over a two-dimensional approach to rearfoot analysis has been questioned in the past. The purpose of this study was to examine differences in typical rearfoot variables obtained using a two-dimensional analysis compared with a three-dimensional approach. In addition, the influence of foot placement angle on these differences was assessed. Two- and three-dimensional rearfoot kinematics were collected from 18 recreational runners. Two-dimensional values for eversion at toe-off and time to peak eversion were found to be significantly different from the three-dimensional results. Differences between two-dimensional and three-dimensional variables were magnified with increased toe-out. Differences between eversion values were found to be minimal when the foot was abducted between 7 and 10°. The premise that excessive pronators have more pronounced toe-out was not supported by this study. Results suggest that caution should be exercised when assessing two-dimensional rearfoot motion in subjects with excessive toe-out.

Cilia Microtubule Deformation: A Preliminary Report

1976 ◽  
Vol 34 ◽  
pp. 80-81
Author(s):  
R. Redding
Keyword(s):  
Dimensional Analysis ◽  
Preliminary Report ◽  
Recent Literature ◽  
Three Dimensional ◽  
Curvilinear Relationship ◽  
Two Dimensional ◽  
Dimensional Approach ◽  
Cross Sectional

Various hypotheses for the mechanism of ciliar motility either purport or oppose the concept of microtubule contraction. Recent literature supporting the Sliding Microtubule Model has established that microtubule doublets move relative to one another during the process of bending. Satir (1968) concluded that there is no change of length in the doublets during bending of cilia. He based his conclusion upon: (1) circular relationships and (2) a two dimensional configuration of the microtubules. Accuracy of the circular relationships is dependent upon how close the approximation is to the true curvilinear relationship expressed by a ciliutn. Cross sectional rotation during bending may limit the validity of two dimensional analysis. This communication is a preliminary report on a new, three dimensional approach for determining the deformational characteristics of elongation or shortening of microtubules as they may be expressed in cilia.

Reducing two-dimensional rearfoot motion variability during walking

1993 ◽  
Vol 83 (7) ◽  
pp. 394-397 ◽  
Author(s):  
MW Cornwall ◽  
TG McPoil
Keyword(s):  
Dimensional Analysis ◽  
Clinical Setting ◽  
Three Dimensional ◽  
Movement Analysis ◽  
Two Dimensional ◽  
Motion Measurements ◽  
Time Required ◽  
Rearfoot Motion

Although three-dimensional movement analysis is the preferred method of assessing rearfoot motion during gait, the high cost of equipment and the time required to use it often make it unreasonable or impractical in a clinical setting. The authors discuss a method of minimizing the variability of rearfoot motion measurements during walking, using two-dimensional analysis when three-dimensional is not available to the clinician.

scholarly journals Accurate Characterization of Land Cover in Urban Environments: Determining the Importance of Including Obscured Impervious Surfaces in Urban Heat Island Models

Atmosphere ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 347 ◽  
Author(s):  
Paul Coseo ◽  
Larissa Larsen
Keyword(s):  
Land Cover ◽  
Dimensional Analysis ◽  
Explanatory Power ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Impervious Surfaces ◽  
Dimensional Approach ◽  
Land Cover Types ◽  
Tree Canopies ◽  
Urban Heat

Urban heat islands (UHI) increase summer temperatures and can threaten human well-being during extreme heat events. Since urbanization plays a key role in UHI development, accurate quantification of land cover types is critical to their identification. This study examines how quantifying land cover types using both two- and three-dimensional approaches to land cover quantification affects an UHI model’s explanatory power. Two-dimensional approaches treat tree canopies as a land cover, whereas three-dimensional approaches document the land cover areas obscured under tree canopies. We compare how accurately the two approaches explain elevated air temperatures in Chicago, Illinois. Our results show on average 14.1% of impervious surface areas went undocumented using a two-dimensional approach. The most common concealed impervious surfaces were sidewalks, driveways, and parking lots (+6.2%), followed by roads (+6.1%). Yet, the three-dimensional approach did not improve the explanatory power of a UHI model substantially. At 2 a.m., the adjusted R2 increased from 0.64 for a two-dimensional analysis to 0.68 for a three-dimensional analysis. We found that the less time consuming two-dimensional quantification of land covers was sufficient to predict neighborhood UHIs. As climate change exacerbates UHI, more cities will map urban hotspots and this research increases our understanding of alternative approaches.

Shifting perspectives: method, media and the complex image

1998 ◽  
Vol 10 (1-3) ◽  
pp. 100-108 ◽  
Author(s):  
Alicia Colson ◽  
Ross Parry
Keyword(s):  
Image Processing ◽  
Three Dimensional ◽  
Geographical Location ◽  
Spatial Relationship ◽  
Two Dimensional ◽  
Dimensional Approach ◽  
Complex Image ◽  
Cultural Resonance

This article argues that the analysis of a threedimensional image demanded a three-dimensional approach. The authors realise that discussions of images and image processing inveterately conceptualise representation as being flat, static, and finite. The authors recognise the need for a fresh acuteness to three-dimensionality as a meaningful – although problematic – element of visual sources. Two dramatically different examples are used to expose the shortcomings of an ingrained two-dimensional approach and to facilitate a demonstration of how modern (digital) techniques could sanction new historical/anthropological perspectives on subjects that have become all too familiar. Each example could not be more different in their temporal and geographical location, their cultural resonance, and their historiography. However, in both these visual spectacles meaning is polysemic. It is dependent upon the viewer's spatial relationship to the artifice as well as the spirito-intellectual viewer within the community. The authors postulate that the multi- faceted and multi-layered arrangement of meaning in a complex image could be assessed by working beyond the limitations of the two-dimensional methodological paradigm and by using methods and media that accommodated this type of interconnectivity and representation.

A Three-Dimensional Analysis of Thermohydrodynamic Performance of Sector-Shaped, Tilting-Pad Thrust Bearings

1983 ◽  
Vol 105 (3) ◽  
pp. 406-412 ◽  
Author(s):  
Kyung Woong Kim ◽  
Masato Tanaka ◽  
Yukio Hori
Keyword(s):  
Dimensional Analysis ◽  
Environmental Conditions ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Thrust Bearings ◽  
Tilting Pad ◽  
Dimensional Variation ◽  
Lubricant Viscosity

The thermohydrodynamic performance of the bearing is analyzed, taking into account the three-dimensional variation of lubricant viscosity and density. The effect of pivot position and operating and environmental conditions on the performance is studied. The present analysis is compared with the isoviscous or the two-dimensional analysis, and is found to predict the bearing performance more accurately.

scholarly journals Design and Testing of Swept and Leaned Outlet Guide Vanes to Reduce Stator-Strut-Splitter Aerodynamic Flow Interactions

1998 ◽  
Author(s):  
A. R. Wadia ◽  
P. N. Szucs ◽  
K. L. Gundy-Burlet
Keyword(s):  
Dimensional Analysis ◽  
Test Performance ◽  
Potential Flow ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Angle Distribution ◽  
Two Dimensional ◽  
Guide Vanes ◽  
Flow Interactions ◽  
Design And Testing

Large circumferential varying pressure levels produced by aerodynamic flow interactions between downstream stators and struts present a potential noise and stability margin liability in a compression component. These interactions are presently controlled by tailoring the camber and/or stagger angles of vanes neighboring the fan frame struts. This paper reports on the design and testing of a unique set of swept and leaned fan outlet guide vanes (OGVs) that do not require this local tailoring even though the OGVs are closely coupled with the fan frame struts and splitter to reduce engine length. The swept and leaned OGVs not only reduce core-duct diffusion, but they also reduce the potential flow interaction between the stator and the strut relative to that produced by conventional radial OGVs. First, the design of the outlet guide vanes using a single bladerow three-dimensional viscous flow analysis is outlined. Next, a two-dimensional potential flow analysis was used for the coupled OGV-frame system to obtain a circumferentially non-uniform stator stagger angle distribution to further reduce the upstream static pressure disturbance. Recognizing the limitations of the two-dimensional potential flow analysis for this highly three-dimensional set of leaned OGVs, as a final evaluation of the OGV-strut system design, a full three-dimensional viscous analysis of a periodic circumferential sector of the OGVs, including the fan frame struts and splitter, was performed. The computer model was derived from a NASA-developed code used in simulating the flow field for external aerodynamic applications with complex geometries. The three-dimensional coupled OGV-frame analysis included the uniformly-staggered OGVs configuration and the variably-staggered OGVs configuration determined by the two-dimensional potential flow analysis. Contrary to the two-dimensional calculations, the three-dimensional analysis revealed significant flow problems with the variably-staggered OGVs configuration and showed less upstream flow non-uniformity with the uniformly-staggered OGVs configuration. The flow redistribution in both the radial and tangential directions, captured fully only in the three-dimensional analysis, was identified as the prime contributor to the lower flow non-uniformity with the uniformly-staggered OGVs configuration. The coupled three-dimensional analysis was also used to validate the design at off-design conditions. Engine test performance and stability measurements with both uniformly- and variably-staggered OGVs configurations with and without the presence of inlet distortion confirmed the conclusions from the three-dimensional analysis.

Preliminary Ship Design Using One and Two-Dimensional Models

1999 ◽  
Vol 36 (02) ◽  
pp. 102-112
Author(s):  
Michael D. A. Mackney ◽  
Carl T. F. Ross
Keyword(s):  
Finite Element ◽  
Dimensional Analysis ◽  
Three Dimensional ◽  
Two Dimensional ◽  
One Dimensional ◽  
Dimensional Finite Element ◽  
Dimensional Models ◽  
Support Conditions ◽  
The One ◽  
Three Dimensional Finite Element

Computational studies of hull-superstructure interaction were carried out using one-, two-and three-dimensional finite element analyses. Simplification of the original three-dimensional cases to one- and two-dimensional ones was undertaken to reduce the data preparation and computer solution times in an extensive parametric study. Both the one- and two-dimensional models were evaluated from numerical and experimental studies of the three-dimensional arrangements of hull and superstructure. One-dimensional analysis used a simple beam finite element with appropriately changed sections properties at stations where superstructures existed. Two-dimensional analysis used a four node, first order quadrilateral, isoparametric plane elasticity finite element, with a corresponding increase in the grid domain where the superstructure existed. Changes in the thickness property reflected deck stiffness. This model was essentially a multi-flanged beam with the shear webs representing the hull and superstructure sides, and the flanges representing the decks One-dimensional models consistently and uniformly underestimated the three-dimensional behaviour, but were fast to create and run. Two-dimensional models were also consistent in their assessment, and considerably closer in predicting the actual behaviours. These models took longer to create than the one-dimensional, but ran in very much less time than the refined three-dimensional finite element models Parametric insights were accomplished quickly and effectively with the simplest model and processor, but two-dimensional analyses achieved closer absolute measure of the displacement behaviours. Although only static analysis with simple loading and support conditions were presented, it is believed that similar benefits would be found for other loadings and support conditions. Other engineering components and structures may benefit from similarly judged simplification using one- and two-dimensional models to reduce the time and cost of preliminary design.

Reduction of Three-Dimensional Stress Distributions to Two-Dimensional Analysis by Superposition

1957 ◽  
Vol 24 (3) ◽  
pp. 478-480
Author(s):  
G. A. Zizicas
Keyword(s):  
Dimensional Analysis ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Stress Distributions ◽  
Mohr Circle ◽  
Analytical Results ◽  
Stress Components ◽  
Total Shear

Abstract In a recent note the author proposed a graphical procedure which supplements the classical three-dimensional Mohr-circle representation by specifying the direction of the total shear on any element of surface. The same results are reached here by superposition which simplifies and clarifies the analysis considerably. The associated analytical results are presented in a more useful form and are shown to lead readily to the classical Mohr representation. An application is made to the practically important stress components on the octahedral planes.

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