Influence of the Lateral Ventricles and Irregular Skull Base on Brain Kinematics due to Sagittal Plane Head Rotation

2002 ◽  
Vol 124 (4) ◽  
pp. 422-431 ◽  
Author(s):  
J. Ivarsson ◽  
D. C. Viano ◽  
P. Lo¨vsund
Keyword(s):  
Skull Base ◽  
High Speed ◽  
Sagittal Plane ◽  
Liquid Paraffin ◽  
Angular Acceleration ◽  
Surface Displacement ◽  
Human Head ◽  
Physical Models ◽  
Peak Strain ◽  
Lateral Ventricles

Two-dimensional physical models of the human head were used to investigate how the lateral ventricles and irregular skull base influence kinematics in the medial brain during sagittal angular head dynamics. Silicone gel simulated the brain and was separated from the surrounding skull vessel by paraffin that provided a slip interface between the gel and vessel. A humanlike skull base model (HSB) included a surrogate skull base mimicking the irregular geometry of the human. An HSBV model added an elliptical inclusion filled with liquid paraffin simulating the lateral ventricles to the HSB model. A simplified skull base model (SSBV) included ventricle substitute but approximated the anterior and middle cranial fossae by a flat and slightly angled surface. The models were exposed to 7600 rad/s2 peak angular acceleration with 6 ms pulse duration and 5 deg forced rotation. After 90 deg free rotation, the models were decelerated during 30 ms. Rigid body displacement, shear strain and principal strains were determined from high-speed video recorded trajectories of grid markers in the surrogate brains. Peak values of inferior brain surface displacement and strains were up to 10.9X (times) and 3.3X higher in SSBV than in HSBV. Peak strain was up to 2.7X higher in HSB than in HSBV. The results indicate that the irregular skull base protects nerves and vessels passing through the cranial floor by reducing brain displacement and that the intraventricular cerebrospinal fluid relieves strain in regions inferior and superior to the ventricles. The ventricles and irregular skull base are necessary in modeling head impact and understanding brain injury mechanisms.

scholarly journals Monitoring and Data Analysis in Small-Scale Landslide Physical Model

2021 ◽  
Vol 11 (11) ◽  
pp. 5040
Author(s):  
Sara Pajalić ◽  
Josip Peranić ◽  
Sandra Maksimović ◽  
Nina Čeh ◽  
Vedran Jagodnik ◽  
...  
Keyword(s):  
Physical Modeling ◽  
High Speed ◽  
Laser Scanning ◽  
Surface Displacement ◽  
Physical Models ◽  
Small Scale ◽  
Advantages And Disadvantages ◽  
Artificial Rainfall ◽  
Landslide Development ◽  
Fast Flow

Physical modeling of landslides using scaled landslide models began in the 1970s in Japan at scaled natural slope physical models. Laboratory experiments of landslide behavior in scaled physical models (also known as flume or flume test) started in the 1980s and 1990s in Canada, Japan, and Australia under 1 g conditions. The main purpose of the landslide physical modeling in the last 25 years was research of initiation, motion, and accumulation of fast flow-like landslides caused by infiltration of water in a slope. In October 2018, at the Faculty of Civil Engineering University of Rijeka, started a four-year research project “Physical modeling of landslide remediation constructions’ behavior under static and seismic actions” funded by the Croatian Science Foundation. This paper presents an overview of the methods and monitoring equipment used in the physical models of a sandy slope exposed to artificial rainfall. Landslide development was monitored by observation of volumetric water content and acceleration as well as by observations of surface displacement by means of high-speed stereo cameras, terrestrial laser scanning, and structure-from-motion photogrammetry. Some of the preliminary results of the initial series of experiments are presented, and advantages and disadvantages of the used equipment are discussed.

Experimental Design and Mechanics Study on Brain Injury Tolerance under Sagittal Angular Acceleration Based on Shearing Strain Equivalent Coupling Method

2013 ◽  
Vol 387 ◽  
pp. 55-58
Author(s):  
Sheng Xiong Liu ◽  
Zhi Yong Yin ◽  
Kui Li ◽  
Dai Qin Tao ◽  
Ya Fang Luo ◽  
...  
Keyword(s):  
Human Brain ◽  
High Speed ◽  
Traffic Accidents ◽  
Angular Acceleration ◽  
Physical Models ◽  
Three Dimension ◽  
Human Brain Tissue ◽  
Strain Data ◽  
Injury Tolerance ◽  
Shearing Strain

s: Brain impact injury is the leading cause of death in traffic accidents. In this paper, a brain multi-functional rotary impacting platform will first be set up. After this, the living animal brain sagittally rotary impacts will be executed and the injury tolerance will be achieved. Then, the sagittal physical models of animal and human brains will be produced and the four-point markers will be placed widely on the models sagittal sections. In succession, the high-speed camera and the three-dimension infrared motion analysis meter will be used to record the rotary impacting process, the exterior angular acceleration course and the shearing strain data of interior four-point markers. Thus, with the exterior angular acceleration course, the living animals experiments and the experiments based on the animal physical brain model can be coupled equivalently. In the same way, through the maximum shearing strain data of interior four-point markers, the experiments based on the animal physical brain model can be equivalently coupled with the experiments based on the human physical brain model. Finally, according to the comparability in pathology and physiology between animal and human brain tissue, the injury tolerance of human brain under its sagittally rotary impacts can expect to be obtained through the mechanics study.

scholarly journals Evidence for a vertebrate catapult: elastic energy storage in the plantaris tendon during frog jumping

2011 ◽  
Vol 8 (3) ◽  
pp. 386-389 ◽  
Author(s):  
Henry C. Astley ◽  
Thomas J. Roberts
Keyword(s):  
Energy Storage ◽  
Elastic Energy ◽  
High Speed ◽  
Angular Acceleration ◽  
Whole Body ◽  
Joint Motion ◽  
Joint Movement ◽  
Fascicle Length ◽  
Muscle Fascicle ◽  
Muscle Shortening

Anuran jumping is one of the most powerful accelerations in vertebrate locomotion. Several species are hypothesized to use a catapult-like mechanism to store and rapidly release elastic energy, producing power outputs far beyond the capability of muscle. Most evidence for this mechanism comes from measurements of whole-body power output; the decoupling of joint motion and muscle shortening expected in a catapult-like mechanism has not been demonstrated. We used high-speed marker-based biplanar X-ray cinefluoroscopy to quantify plantaris muscle fascicle strain and ankle joint motion in frogs in order to test for two hallmarks of a catapult mechanism: (i) shortening of fascicles prior to joint movement (during tendon stretch), and (ii) rapid joint movement during the jump without rapid muscle-shortening (during tendon recoil). During all jumps, muscle fascicles shortened by an average of 7.8 per cent (54% of total strain) prior to joint movement, stretching the tendon. The subsequent period of initial joint movement and high joint angular acceleration occurred with minimal muscle fascicle length change, consistent with the recoil of the elastic tendon. These data support the plantaris longus tendon as a site of elastic energy storage during frog jumping, and demonstrate that catapult mechanisms may be employed even in sub-maximal jumps.

scholarly journals A Hybrid Remaining Useful Life Prediction Method for Cutting Tool Considering the Wear State

2022 ◽  
Author(s):  
Yifan Li ◽  
Yongyong Xiang ◽  
Baisong Pan ◽  
Luojie Shi
Keyword(s):  
Tool Wear ◽  
High Speed ◽  
Cutting Tool ◽  
Bayesian Framework ◽  
Remaining Useful Life ◽  
Physical Models ◽  
Data Driven ◽  
Support Vector ◽  
Wear Model ◽  
Useful Life

Abstract Accurate cutting tool remaining useful life (RUL) prediction is of significance to guarantee the cutting quality and minimize the production cost. Recently, physics-based and data-driven methods have been widely used in the tool RUL prediction. The physics-based approaches may not accurately describe the time-varying wear process due to a lack of knowledge for underlying physics and simplifications involved in physical models, while the data-driven methods may be easily affected by the quantity and quality of data. To overcome the drawbacks of these two approaches, a hybrid prognostics framework considering tool wear state is developed to achieve an accurate prediction. Firstly, the mapping relationship between the sensor signal and tool wear is established by support vector regression (SVR). Then, the tool wear statuses are recognized by support vector machine (SVM) and the results are put into a Bayesian framework as prior information. Thirdly, based on the constructed Bayesian framework, parameters of the tool wear model are updated iteratively by the sliding time window and particle filter algorithm. Finally, the tool wear state space and RUL can be predicted accordingly using the updating tool wear model. The validity of the proposed method is demonstrated by a high-speed machine tool experiment. The results show that the presented approach can effectively reduce the uncertainty of tool wear state estimation and improve the accuracy of RUL prediction.

scholarly journals Operation of the alula as an indicator of gear change in hoverflies

2011 ◽  
Vol 9 (71) ◽  
pp. 1194-1207 ◽  
Author(s):  
Simon M. Walker ◽  
Adrian L. R. Thomas ◽  
Graham K. Taylor
Keyword(s):  
High Speed ◽  
Aerodynamic Force ◽  
Angular Acceleration ◽  
The State ◽  
The Body ◽  
Kinematic Parameters ◽  
Wing Kinematics ◽  
Change Mechanism ◽  
The Third ◽  
Gear Change

The alula is a hinged flap found at the base of the wings of most brachyceran Diptera. The alula accounts for up to 10 per cent of the total wing area in hoverflies (Syrphidae), and its hinged arrangement allows the wings to be swept back over the thorax and abdomen at rest. The alula is actuated via the third axillary sclerite, which is a component of the wing hinge that is involved in wing retraction and control. The third axillary sclerite has also been implicated in the gear change mechanism of flies. This mechanism allows rapid switching between different modes of wing kinematics, by imposing or removing contact with a mechanical stop limiting movement of the wing during the lower half of the downstroke. The alula operates in two distinct states during flight—flipped or flat—and we hypothesize that its state indicates switching between different flight modes. We used high-speed digital video of free-flying hoverflies ( Eristalis tenax and Eristalis pertinax ) to investigate whether flipping of the alula was associated with changes in wing and body kinematics. We found that alula state was associated with different distributions of multiple wing kinematic parameters, including stroke amplitude, stroke deviation angle, downstroke angle of incidence and timing of supination. Changes in all of these parameters have previously been linked to gear change in flies. Symmetric flipping of the alulae was associated with changes in the symmetric linear acceleration of the body, while asymmetric flipping of the alulae was associated with asymmetric angular acceleration of the body. We conclude that the wings produce less aerodynamic force when the alula is flipped, largely as a result of the accompanying changes in wing kinematics. The alula changes state at mid-downstroke, which is the point at which the gear change mechanism is known to come into effect. This transition is accompanied by changes in the other wing kinematic parameters. We therefore find that the state of the alula is linked to the same parameters as are affected by the gear change mechanism. We conclude that the state of the alula does indeed indicate the operation of different flight modes in Eristalis , and infer that a likely mechanism for these changes in flight mode is the gear change mechanism.

scholarly journals Measurement of Strain in Physical Models of Brain Injury: A Method Based on HARP Analysis of Tagged Magnetic Resonance Images (MRI)

2004 ◽  
Vol 126 (4) ◽  
pp. 523-528 ◽  
Author(s):  
P. V. Bayly, ◽  
S. Ji, ◽  
S. K. Song, ◽  
R. J. Okamoto, ◽  
P. Massouros, ◽  
...  
Keyword(s):  
Brain Injury ◽  
Magnetic Resonance ◽  
Closed Head Injury ◽  
Angular Acceleration ◽  
Strain Analysis ◽  
Experimental Models ◽  
Magnetic Resonance Images ◽  
Physical Models ◽  
Harmonic Phase ◽  
Closed Head

Two-dimensional (2-D) strain fields were estimated non-invasively in two simple experimental models of closed-head brain injury. In the first experimental model, shear deformation of a gel was induced by angular acceleration of its spherical container. In the second model the brain of a euthanized rat pup was deformed by indentation of its skull. Tagged magnetic resonance images (MRI) were obtained by gated image acquisition during repeated motion. Harmonic phase (HARP) images corresponding to the spectral peaks of the original tagged MRI were obtained, following procedures proposed by Osman, McVeigh and Prince [1]. Two methods of HARP strain analysis were applied, one based on the displacement of tag line intersections, and the other based on the gradient of harmonic phase. Strain analysis procedures were also validated on simulated images of deformed grids. Results show that it is possible to visualize deformation and to quantify strain efficiently in animal models of closed head injury.

Sagittal and Coronal Dimensions of the Ethmoid Roof: A Radioanatomic Study

2005 ◽  
Vol 19 (4) ◽  
pp. 348-352 ◽  
Author(s):  
Mark A. Zacharek ◽  
Joseph K. Han ◽  
Robert Allen ◽  
Jane L. Weissman ◽  
Peter H. Hwang
Keyword(s):  
Skull Base ◽  
Normative Data ◽  
Sagittal Plane ◽  
Ethmoid Sinus ◽  
Nasal Floor ◽  
Equidistant Points ◽  
The Right ◽  
3D Software ◽  
Anterior Ethmoid Artery ◽  
Ct Studies

Background Understanding the anatomy of the ethmoid roof is critical to safe surgical outcomes. Normative data regarding the height and slope of this region have been somewhat limited, derived primarily from cadaveric coronal computed tomography (CT) studies. With triplanar imaging programs, precise multidimensional measurements of the ethmoid roof are now possible. We present a radioanatomic study to characterize normative sagittal and coronal dimensions of the ethmoid roof. Methods Bilateral measurements were taken in 100 consecutive sinus CT scans using ThinClient 3D software. In the sagittal plane, the height of the ethmoid roof was measured in quadrants at five equidistant points between the frontal beak and sphenoid face, referencing the nasal floor. In the coronal plane, the ethmoid roof was measured at three points at the level of the anterior ethmoid artery and at two points at the junction of the posterior ethmoid and sphenoid sinuses. Results When examined sagittally, the right side showed significantly lower skull base heights in the anterior ethmoid compared with the left side (59.0 mm versus 59.8 mm, p = 0.017; 53.7 mm versus 54.5 mm, p = 0.0004). Coronal measurements of the anterior ethmoid roof showed similar significant differences. The anterior ethmoid roof had greater asymmetries of height compared with the posterior ethmoid roof, which was fairly constant. Conclusion This study provides numerical correlates to accepted concepts regarding the shape and slope of the ethmoid roof. Differences in height of the skull base between right and left sides, especially in the anterior ethmoid sinus, may be an important surgical consideration. The posterior ethmoid roof appears to be relatively constant and should serve as a reliable surgical landmark.

scholarly journals Effect of different helmet shell configurations on the protection against head trauma

2019 ◽  
Vol 54 (7-8) ◽  
pp. 408-415 ◽  
Author(s):  
Marta Palomar ◽  
Ricardo Belda ◽  
Eugenio Giner
Keyword(s):  
Head Trauma ◽  
High Speed ◽  
Composite Shell ◽  
Human Head ◽  
High Rate ◽  
Finite Element Models ◽  
High Speed Impact ◽  
Full Metal Jacket ◽  
The Impact ◽  
Single Combat

Head trauma following a ballistic impact in a helmeted head is assessed in this work by means of finite element models. Both the helmet and the head models employed were validated against experimental high-rate impact tests in a previous work. Four different composite ply configurations were tested on the helmet shell, and the energy absorption and the injury outcome resulting from a high-speed impact with full metal jacket bullets were computed. Results reveal that hybrid aramid–polyethylene configurations do not prevent bullet penetration at high velocities, while 16-layer aramid configurations are superior in dissipating the energy absorbed from the impact. The fabric orientation of these laminates proved to be determinant for the injury outcome, as maintaining the same orientations for all the layers led to basilar skull fractures (dangerous), while alternating orientation of the adjacent plies resulted in an undamaged skull. To the authors knowledge, no previous work in the literature has analysed numerically the influence of different stack configurations on a single combat helmet composite shell on human head trauma.

scholarly journals The Geometry and Mechanics of Insect Wing Deformations in Flight: A Modelling Approach

Insects ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 446
Author(s):  
Robin Wootton
Keyword(s):  
Remote Control ◽  
Deformation Process ◽  
High Speed ◽  
Physical Models ◽  
Insect Wing ◽  
Stable Conditions ◽  
Torsional Component ◽  
Wing Deformation ◽  
Shaped Section ◽  
Modelling Approach

The nature, occurrence, morphological basis and functions of insect wing deformation in flight are reviewed. The importance of relief in supporting the wing is stressed, and three types are recognized, namely corrugation, an M-shaped section and camber, all of which need to be overcome if wings are to bend usefully in the morphological upstroke. How this is achieved, and how bending, torsion and change in profile are mechanically interrelated, are explored by means of simple physical models which reflect situations that are visible in high speed photographs and films. The shapes of lines of transverse flexion are shown to reflect the timing and roles of bending, and their orientation is shown to determine the extent of the torsional component of the deformation process. Some configurations prove to allow two stable conditions, others to be monostable. The possibility of active remote control of wing rigidity by the thoracic musculature is considered, but the extent of this remains uncertain.

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