3D ultrasound as sparse data for intraoperative brain deformation model

2001 ◽  
Author(s):  
Karen E. Lunn ◽  
Alex Hartov ◽  
Francis E. Kennedy ◽  
Michael I. Miga ◽  
David W. Roberts ◽  
...  
Keyword(s):  
3D Ultrasound ◽  
Sparse Data ◽  
Deformation Model ◽  
Brain Deformation

Development of a Single-Degree-of-Freedom Mechanical Model for Predicting Strain-Based Brain Injury Responses

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Lee F. Gabler ◽  
Hamed Joodaki ◽  
Jeff R. Crandall ◽  
Matthew B. Panzer
Keyword(s):  
Brain Injury ◽  
Degree Of Freedom ◽  
Deformation Model ◽  
Maximum Magnitude ◽  
Natural Period ◽  
Single Degree Of Freedom ◽  
Head Kinematics ◽  
Single Degree ◽  
Brain Deformation ◽  
Deformation Mechanics

Linking head kinematics to injury risk has been the focus of numerous brain injury criteria. Although many early forms were developed using mechanics principles, recent criteria have been developed using empirical methods based on subsets of head impact data. In this study, a single-degree-of-freedom (sDOF) mechanical analog was developed to parametrically investigate the link between rotational head kinematics and brain deformation. Model efficacy was assessed by comparing the maximum magnitude of displacement to strain-based brain injury predictors from finite element (FE) human head models. A series of idealized rotational pulses covering a broad range of acceleration and velocity magnitudes (0.1–15 krad/s2 and 1–100 rad/s) with durations between 1 and 3000 ms were applied to the mechanical models about each axis of the head. Results show that brain deformation magnitude is governed by three categories of rotational head motion each distinguished by the duration of the pulse relative to the brain's natural period: for short-duration pulses, maximum brain deformation depended primarily on angular velocity magnitude; for long-duration pulses, brain deformation depended primarily on angular acceleration magnitude; and for pulses relatively close to the natural period, brain deformation depended on both velocity and acceleration magnitudes. These results suggest that brain deformation mechanics can be adequately explained by simple mechanical systems, since FE model responses and experimental brain injury tolerances exhibited similar patterns to the sDOF model. Finally, the sDOF model was the best correlate to strain-based responses and highlighted fundamental limitations with existing rotational-based brain injury metrics.

In vivo quantification of a homogeneous brain deformation model for updating preoperative images during surgery

2000 ◽  
Vol 47 (2) ◽  
pp. 266-273 ◽  
Author(s):  
M.I. Miga ◽  
K.D. Paulsen ◽  
P.J. Hoopes ◽  
F.E. Kennedy ◽  
A. Hartov ◽  
...  
Keyword(s):  
Deformation Model ◽  
Brain Deformation

Placental volume measurement by 3D-ultrasound in the first trimester and prediction of fetal growth

2008 ◽  
Vol 68 (S 01) ◽  
Author(s):  
B Meurer ◽  
B Meurer ◽  
N Dinkel ◽  
N Hart ◽  
J Siemer ◽  
...  
Keyword(s):  
Fetal Growth ◽  
First Trimester ◽  
3D Ultrasound ◽  
Volume Measurement ◽  
Placental Volume

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

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