Flow and Compression in Asymmetric Stenosis Models: Influence of Compliance on Flow and Compression

2002 ◽  
Author(s):  
Shunichi Kobayashi ◽  
Daisuke Tsunoda ◽  
Hirohisa Morikawa ◽  
Dalin Tang ◽  
David N. Ku
Keyword(s):  
Pulsatile Flow ◽  
High Speed ◽  
Fluid Pressure ◽  
Arterial Disease ◽  
External Pressure ◽  
Distal Embolization ◽  
Severe Stenosis ◽  
Internal Fluid ◽  
Flow Through ◽  
Flow Experiments

Blood flow through the constricted area of a severe stenosis is similar to that through a venturi or flow nozzle. In the contraction section, the blood can accelerate to high speed. In this situation, the external pressure may be greater than the internal fluid pressure, and the artery could collapse. This collapse may be important in the development of atherosclerotic plaque fracture and subsequent thrombosis or distal embolization [1]. We have developed an asymmetric experimental model that closely approximates the arterial disease situation and performed steady and pulsatile flow experiments. The characteristics of flow and compression concerned with the geometry of the model were discussed [2, 3]. This paper was to examine the influence of compliance on flow and compression under steady and pulsatile flow.

Pulsatile Flow and Deformation in Curved Stenosis Models of Arterial Disease

2004 ◽  
Author(s):  
Shunichi Kobayashi ◽  
Yutaka Fukuzawa ◽  
Yuuki Ayama ◽  
Hirohisa Morikawa ◽  
Dalin Tang ◽  
...  
Keyword(s):  
Experimental Model ◽  
Pulsatile Flow ◽  
Coronary Stenosis ◽  
High Speed ◽  
Fluid Pressure ◽  
Arterial Disease ◽  
External Pressure ◽  
Internal Fluid ◽  
Flow Through ◽  
Flow Experiments

Blood flow through the constricted area of a severe stenosis is similar to that through a venturi or flow nozzle. In the contraction section, the blood can accelerate to high speed. In this situation, the external pressure may be greater than the internal fluid pressure, and the artery could collapse. This collapse may be important in the development of atherosclerotic plaque fracture and subsequent thrombosis or distal embolization. We have developed an experimental model that closely approximates the arterial disease situation and performed steady and pulsatile flow experiments, and the characteristics of flow and compression concerned with the geometry and compliance of the model were discussed [1]. But we had not focused on the coronary stenosis. As the first step to develop the experimental model of coronary stenosis, the curved stenosis model was made. This paper was to examine the influence of curvature and stretch of the stenosis model on flow and collapse under pulsatile flow.

Nonquasi-Steady Character of Pulsatile Flow in Human Coronary Arteries

1985 ◽  
Vol 107 (1) ◽  
pp. 24-28 ◽  
Author(s):  
F. F. Mark ◽  
C. B. Bargeron ◽  
O. J. Deters ◽  
M. H. Friedman
Keyword(s):  
Coronary Arteries ◽  
Pulsatile Flow ◽  
Laser Doppler Anemometry ◽  
Main Channel ◽  
Left Main ◽  
Vascular Cast ◽  
Pulsatile Flows ◽  
Flow Through ◽  
The Mean ◽  
Flow Experiments

This experiment was conducted to determine if the pulsatile flow through the proximal portion of the left coronary artery system in man exhibits quasi-steady characteristics. Steady and pulsatile flows were passed through an idealized model whose dimensions were based on a vascular cast. The mean Reynolds number was 180 and the unsteadiness number was 2.7. Velocity profiles were measured by laser Doppler anemometry at several locations along diameters in the parent and both daughter channels in the neighborhood of the “left main” bifurcation. Analysis of the results along one diameter in the “left main” channel shows that unsteady flow in the larger coronary arteries may not be simulated by a series of steady flow experiments.

Pulsatile flow through a bifurcation with applications to arterial disease

1976 ◽  
Vol 9 (9) ◽  
pp. 575-580 ◽  
Author(s):  
R.C. Fernandez ◽  
K.J. De Witt ◽  
M.R. Botwin
Keyword(s):  
Pulsatile Flow ◽  
Arterial Disease ◽  
Flow Through

In-Plane Parametric Vibrations of Curved Bellows Subjected to Oscillating Internal Fluid Pressure Excitation

2004 ◽  
Author(s):  
Masahiro Watanabe ◽  
Eiji Tachibana ◽  
Nobuyuki Kobayashi
Keyword(s):  
Stability Analysis ◽  
Natural Frequencies ◽  
Parametric Instability ◽  
Fluid Pressure ◽  
Parametric Vibrations ◽  
Internal Fluid ◽  
Mathieu’S Equation ◽  
Stability Maps ◽  
Plane Direction ◽  
Pressure Excitation

This paper deals with the theoretical stability analysis of in-plane parametric vibrations of a curved bellows subjected to periodic internal fluid pressure excitation. The curved bellows studied in this paper are fixed at both ends rigidly, and are excited by the periodic internal fluid pressure. In the theoretical stability analysis, the governing equation of the curved bellows subjected to periodic internal fluid pressure excitation is derived as a Mathieu’s equation by using finite element method (FEM). Natural frequencies of the curved bellows are examined and stability maps are presented for in-plane parametric instability. It is found that the natural frequencies of the curved bellows decrease with increasing the static internal fluid pressure and buckling occurs due to high internal fluid pressure. It is also found that two types of parametric vibrations, longitudinal and transverse vibrations, occur to the curved bellows in-plane direction due to the periodic internal fluid pressure excitation. Moreover, effects of axis curvature on the parametric instability regions are examined theoretically.

scholarly journals Tactile Perception for Teleoperated Robotic Exploration within Granular Media

2021 ◽  
Vol 10 (4) ◽  
pp. 1-27
Author(s):  
Shengxin Jia ◽  
Veronica J. Santos
Keyword(s):  
Granular Media ◽  
Fluid Pressure ◽  
Tactile Sensor ◽  
Tactile Perception ◽  
Test Accuracy ◽  
Contact State ◽  
Buried Objects ◽  
Media Type ◽  
Additional Information ◽  
Internal Fluid

The sense of touch is essential for locating buried objects when vision-based approaches are limited. We present an approach for tactile perception when sensorized robot fingertips are used to directly interact with granular media particles in teleoperated systems. We evaluate the effects of linear and nonlinear classifier model architectures and three tactile sensor modalities (vibration, internal fluid pressure, fingerpad deformation) on the accuracy of estimates of fingertip contact state. We propose an architecture called the Sparse-Fusion Recurrent Neural Network (SF-RNN) in which sparse features are autonomously extracted prior to fusing multimodal tactile data in a fully connected RNN input layer. The multimodal SF-RNN model achieved 98.7% test accuracy and was robust to modest variations in granular media type and particle size, fingertip orientation, fingertip speed, and object location. Fingerpad deformation was the most informative modality for haptic exploration within granular media while vibration and internal fluid pressure provided additional information with appropriate signal processing. We introduce a real-time visualization of tactile percepts for remote exploration by constructing a belief map that combines probabilistic contact state estimates and fingertip location. The belief map visualizes the probability of an object being buried in the search region and could be used for planning.

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