scholarly journals Bond Graph Model of Cerebral Circulation: Toward Clinically Feasible Systemic Blood Flow Simulations

2020 ◽  
Author(s):  
Shan Su ◽  
Pablo J. Blanco ◽  
Lucas O. Müller ◽  
Peter J. Hunter ◽  
Soroush Safaei
Keyword(s):  
Cerebral Circulation ◽  
Graph Model ◽  
Bond Graph ◽  
The Body ◽  
Lumped Parameter Model ◽  
Desktop Computer ◽  
Detailed Model ◽  
Simulation Speed ◽  
Lumped Parameter ◽  
Proposed Model

The primary paper Safaei et al. (2018) proposed an anatomically detailed model of the human cerebral circulation that runs faster than real-time on a desktop computer and is designed for use in clinical settings when the speed of response is important. Based on a one-dimensional formulation of the flow of an incompressible fluid in distensible vessels, a lumped parameter model was developed for 218 arterial segments. The proposed model improved simulation speed by approximately 200-fold while preserved accuracy. Bond graph formulation was used to ensure mass and energy conservation. The model predicted the pressure and flow signatures in the body.

scholarly journals Bond Graph Model of Cerebral Circulation: Toward Clinically Feasible Systemic Blood Flow Simulations

2020 ◽  
Author(s):  
Shan Su ◽  
Pablo J. Blanco ◽  
Lucas O. Müller ◽  
Peter J. Hunter ◽  
Soroush Safaei
Keyword(s):  
Cerebral Circulation ◽  
Graph Model ◽  
Bond Graph ◽  
The Body ◽  
Lumped Parameter Model ◽  
Desktop Computer ◽  
Detailed Model ◽  
Simulation Speed ◽  
Lumped Parameter ◽  
Proposed Model

The primary paper Safaei et al. (2018) proposed an anatomically detailed model of the human cerebral circulation that runs faster than real-time on a desktop computer and is designed for use in clinical settings when the speed of response is important. Based on a one-dimensional formulation of the flow of an incompressible fluid in distensible vessels, a lumped parameter model was developed for 218 arterial segments. The proposed model improved simulation speed by approximately 200-fold while preserved accuracy. Bond graph formulation was used to ensure mass and energy conservation. The model predicted the pressure and flow signatures in the body.

A Lumped Parameter Electromechanical Model for Describing the Nonlinear Behavior of Piezoelectric Actuators

1997 ◽  
Vol 119 (3) ◽  
pp. 478-485 ◽  
Author(s):  
M. Goldfarb ◽  
N. Celanovic
Keyword(s):  
System Analysis ◽  
Nonlinear Behavior ◽  
Piezoelectric Actuators ◽  
Bond Graph ◽  
Lumped Parameter Model ◽  
Input Output ◽  
Mechanical Stiffness ◽  
Analysis And Design ◽  
Lumped Parameter ◽  
Proposed Model

A lumped-parameter model of a piezoelectric stack actuator has been developed to describe actuator behavior for purposes of control system analysis and design, and in particular for control applications requiring accurate position tracking performance. In addition to describing the input-output dynamic behavior, the proposed model explains aspects of nonintuitive behavioral phenomena evinced by piezoelectric actuators, such as the input-output rate-independent hysteresis and the change in mechanical stiffness that results from altering electrical load. Bond graph terminology is incorporated to facilitate the energy-based formulation of the actuator model. The authors propose a new bond graph element, the generalized Maxwell resistive capacitor, as a lumped-parameter causal representation of rate-independent hysteresis. Model formulation is validated by comparing results of numerical simulations to experimental data.

Bond Graph Sign Conventions

1975 ◽  
Vol 97 (2) ◽  
pp. 184-188 ◽  
Author(s):  
A. S. Perelson
Keyword(s):  
Graph Model ◽  
Bond Graph ◽  
Equivalence Classes ◽  
Parameter System ◽  
Bond Graphs ◽  
Lumped Parameter ◽  
Oriented Object

The lack of arbitrariness in the choice of bond graph sign conventions is established. It is shown that an unoriented bond graph may have no unique meaning and that with certain choices of orientation a bond graph may not correspond to any lumped parameter system constructed from the same set of elements. Network interpretations of these two facts are given. Defining a bond graph as an oriented object leads to the consideration of equivalence classes of oriented bond graphs which represent the same system. It is also shown that only changes in the orientation of bonds connecting 0-junctions and 1-junctions can lead to changes in the observable properties of a bond graph model.

scholarly journals Bond Graph Model of Cerebral Circulation: Toward Clinically Feasible Systemic Blood Flow Simulations

2018 ◽  
Vol 9 ◽  
Author(s):  
Soroush Safaei ◽  
Pablo J. Blanco ◽  
Lucas O. Müller ◽  
Leif R. Hellevik ◽  
Peter J. Hunter
Keyword(s):  
Blood Flow ◽  
Cerebral Circulation ◽  
Graph Model ◽  
Bond Graph ◽  
Systemic Blood ◽  
Systemic Blood Flow ◽  
Flow Simulations

Lumped Parameter Modeling of Counterbalance Valves Considering the Effect of Flow Forces

2019 ◽  
Author(s):  
Annalisa Sciancalepore ◽  
Andrea Vacca ◽  
Oscar Pena ◽  
Steven T. Weber
Keyword(s):  
Controller Design ◽  
Complex Geometry ◽  
Control Volume ◽  
Analytical Description ◽  
Lumped Parameter Model ◽  
Hydraulic Control ◽  
Lumped Parameter ◽  
Proposed Model ◽  
Lumped Parameter Models ◽  
High Level

Abstract The lumped parameter approach based on equations describing of the physical behavior of the system still represents one of the most convenient way to simulate hydraulic control systems. The key advantages of this approach are given by its intrinsic simulation swiftness as well as the ease of deriving state space formulations for controller design purposes. However, the common limitation of lumped parameter models is the high level of simplification of for certain physical aspects. For the case of hydraulic control valves with complex geometry, the flow forces are usually one of the most difficult aspects to describe accurately. The present paper presents a lumped parameter model for counterbalance valves, which includes an accurate analytical approach to model the effect of the flow forces based acting on the valve poppet and piston. The model is based on a classic control volume scheme for the description of the flow through the valve, and it is coupled with a dynamic model for the descriptions of the motion of the moving parts inside the valve. The novelty of the proposed approach consists on the analytical description of the flow forces, which is based on fluid momentum considerations. After describing the modeling approach, the paper details the authors’ efforts for experimentally validate the model on the basis of tests performed on actual components. The comparison between simulation results and experimental data confirms the validity of the proposed model and also highlights the importance of accounting for flow forces while describing the operation of counterbalance valves, particularly for cases of high flow rates.

Initial Steps Toward Development of a Lumped-Parameter Model of the Lymphatic Network

2013 ◽  
Author(s):  
Samira Jamalian ◽  
Christopher D. Bertram ◽  
James E. Moore
Keyword(s):  
Blood Circulation ◽  
Lymphatic Vessel ◽  
Lymphatic System ◽  
Lymphatic Vessels ◽  
The Body ◽  
Lumped Parameter Model ◽  
Circulation System ◽  
Blood Circulation System ◽  
Lumped Parameter ◽  
Lymphatic Network

One of the primary functions of the lymphatic system is maintaining fluid and protein balance in the body. The system holds this balance by collecting about four liters of fluid every day from the interstitial space and returning it back to the subclavian vein. In contrast to the blood circulation system that relies on the heart for pumping, there is no central pump in the lymphatic system. Thus, the transport of viscous fluid against gravity and pressure difference occurs by recruiting extrinsic and intrinsic pumping mechanisms. Extrinsic pumping is the transport of lymph due to the movements outside the lymphatic vessel such as the pulse in blood vessels, whereas the intrinsic pumping is transport of lymph by contraction of lymphatic muscle cells embedded in the walls of lymphatic vessels. Similar to the veins, the bi-leaflet valves throughout the lymphatic network prevent backflow. Lymphatic valves are biased open and allow for small amounts of back flow before they completely shut.

Modeling of the Seated Human Body in a Vibrational Medium

2014 ◽  
Vol 658 ◽  
pp. 401-406 ◽  
Author(s):  
Daniela Mariana Barbu
Keyword(s):  
Human Body ◽  
Degrees Of Freedom ◽  
Dynamic Environment ◽  
The Body ◽  
Lumped Parameter Model ◽  
Vibration Effect ◽  
Mechanical Oscillations ◽  
Lumped Parameter ◽  
Irregular Period ◽  
Multi Body

Vibrations are mechanical oscillations produced by regular or irregular period movements of a member or body about its rest position. Vibration can affect visual perception, muscles, concentration, circulation and the respiratory system and at certain levels can even result in physical harm to the body. The effect of vibration on the human body is related to the natural frequency of parts of the human body affected. This paper studies the dynamic characteristics of a seated human body system in a vibration environment. The main result is a multi degrees of freedom lumped parameter model. The model provided an analytical tool for human body dynamics research. It also enabled a primary tool for seat and cushioning design. Combining the geometry and the mechanical characteristics of a structure under large deformation into a lumped parameter model enables successful analysis of the human/seat interface system and provides practical results for body protection in dynamic environment. The relative displacements of human parts are evaluated, which can be a basis for the assessment of vibration risk. It is suggested that the multi-body dynamic model is used to evaluate the vibration effect to the seated subjects.

Estimation of otoacoustic emission and excitation force of bone conduction actuator by combined lumped parameter model

2021 ◽  
Vol 263 (1) ◽  
pp. 5012-5018
Author(s):  
Akiko Fujise
Keyword(s):  
Equivalent Circuit ◽  
Preliminary Investigation ◽  
Bone Conduction ◽  
Otoacoustic Emission ◽  
The Body ◽  
Lumped Parameter Model ◽  
Environmental Sound ◽  
Optimal Output ◽  
Lumped Parameter ◽  
Parameter Values

In sound presentation system using actuators which excite the surface of the pinna or head, both otoacoustic emission and vibration transmission inside the body contribute to the perception of the sound. The contribution of these pathways is affected by both the location of the excitation and mechanical characteristic of the actuator, leaving the optimal output level of the actuator to mask environmental sound or to present information yet to be estimated. This study, therefore, proposes a simplified model which combines an acoustic equivalent circuit of ear canal and a mechanical equivalent circuit of the tissues of the head. The model enables to estimate both otoacoustic emission component directly corresponding with the loudness for air conducted sound and the component of the transmission inside the head which requires the measurement of the loudness level individually by each excitation location. As the preliminary investigation preceding the establishment of the proposed model towards the human, these two components were calculated using the known parameter values for artificial ear and artificial mastoid. The results indicate that the stiffness of the excited soft tissue and the type of the actuator strongly affect the cutoff frequencies, resonances, and anti-resonances observed within the audible range.

Hybrid Dynamic Modeling and Analysis of High-speed Thin-rimmed Gears

2021 ◽  
pp. 1-23
Author(s):  
Changzhao Liu ◽  
Yu Zhao ◽  
Yong Wang ◽  
Tie Zhang ◽  
Hanjie Jia
Keyword(s):  
Finite Element ◽  
Dynamic Model ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Lumped Parameter Model ◽  
Modeling And Analysis ◽  
Lumped Parameter ◽  
Proposed Model ◽  
Angular Displacements

Abstract In this study, a hybrid dynamic model of high-speed thin-rimmed gears is developed. In this model, the translational and angular displacements (including the rigid and vibration displacements) with a total of six degrees of freedom (DOFs) are selected as the generalized coordinates for each gear, and the meshing force distributions along the contact line and between the teeth are considered. Thus, the model can be implemented under stationary and non-stationary conditions. The condensed finite element models are developed with the centrifugal and inertia forces for gear bodies. This paper proposes a novel method to couple the lumped parameter model and condensed finite element model for the hybrid dynamic model system, which considers the variation of the meshing tooth during the gear operation, namely, the variations of the acting point of meshing force. Based on the model, the dynamic analysis of high-speed thin-rimmed gears is conducted under stationary speed and acceleration processes. The effects of the flexible gear body, high speed, and tooth errors on the system dynamics and tooth load distribution are investigated. The analysis results are also compared with the current reference and pure finite element method to validate the proposed model.

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