scholarly journals Simulation of the Cardiovascular Mechanical System Based on Pressure-Flow Model Rest Condition

2020 ◽  
Vol 5 (7) ◽  
pp. 104-115
Author(s):  
Dimas Primasatya ◽  
Erry Rimawan ◽  
Hendi Herlambang ◽  
Horas Canman S
Keyword(s):  
Cardiovascular System ◽  
Flow Model ◽  
Physiological State ◽  
Left Ventricular ◽  
Ventricular Pressure ◽  
Parameter Method ◽  
Pressure Flow ◽  
Lumped Parameter ◽  
Rest Condition ◽  
Lumped Parameter Method

Non-invasive measurement method has made rapid developments in the field of biomedical engineering. One of research is impedance cardiography (ICG), which provide information of pulsation basic. By knowing this kind of measurement technique, it will assist inspection of the patient's physiological condition with cardiovascular system. This research is aimed to determine the mechanical characteristics of the cardiovascular system in the human body such as a wave graph of pressure, flow, and volume, based on pressure–flow model in rest condition, and analyze the simulation results by implementing state of the physiology cardiovascular disease. To obtain the wave chart that is modeled by the cardiovascular system using a lumped parameter method, formulate the differential equations of the pressure–flow dynamics equation for an incompressible fluid in a segment of a cylindrical elastic tube and simulate the model using the Simulink toolboxes from Matlab R2008b. The simulation with lumped parameter method resulted wave graphics of pressure, flow, and volume of physiological state a person in rest condition, the left ventricular pressure is 120 mmHg , right ventricular pressure is 30 mmHg , left ventricular outflow is 800 mL / sec and volume in the left ventricle is 160 mL . By implementing the simulation have been developed on the physiological state of cardiovascular disease, hypertension occurs when the arteries resistance R3i = 0.61 mmHg × s mL with the pressure of the left ventricle is 145 mmHg. For coronary heart condition, ventricular pressure decreased until 82 mmHg in the value of the coronary arteries resistance is R3o = 0.852 mmHg × s mL. This research assumed heart haves the character of passive because there is no feedback signal that can compensate if the pressure in the systemic circulation is reduced. The research can be concluded that the graph from simulation shows the results are not much different from the reference chart, this results indicates that the equation and the simulation was able to reflect on the human circulatory physiological circumstances. A little different of a graphic simulation result due to differences in the parameters and assumptions used.

An improved lumped parameter method for calculating static characteristics of multi-recess hydrostatic journal bearings

2019 ◽  
Vol 234 (2) ◽  
pp. 301-310
Author(s):  
Yongtao Zhang ◽  
Shijie Yu ◽  
Changhou Lu ◽  
Haixia Zhao ◽  
Peng Liang
Keyword(s):  
Total Pressure ◽  
Control Volume ◽  
Journal Bearings ◽  
Parameter Method ◽  
Static Characteristics ◽  
Application Range ◽  
Continuity Equations ◽  
Pressure Distributions ◽  
Lumped Parameter ◽  
Lumped Parameter Method

This paper proposes an improved lumped parameter method for calculating the static characteristics of multi-recess hydrostatic journal bearings. The improved lumped parameter method can estimate the total pressure distribution in the circumferential direction by introducing control volume in the middle of each inter-recess land, and utilizing the flow continuity equations for each recess and each control volume with the assumption that the pressure distributions are parabolic on the inter-recess land. Then the recess pressure and the fluid film force can be calculated. The calculation accuracy of the improved lumped parameter method and the traditional lumped parameter method is comparatively discussed under different eccentricity ratios and wrap angles of the recess. The results show that the improved lumped parameter method has higher calculation accuracy and wider application range.

Effects of arterial input impedance on mean ventricular pressure-flow relation

1984 ◽  
Vol 247 (6) ◽  
pp. H978-H983 ◽  
Author(s):  
W. L. Maughan ◽  
K. Sunagawa ◽  
K. Sagawa
Keyword(s):  
Characteristic Impedance ◽  
Peripheral Resistance ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Ventricular Pressure ◽  
Pressure Flow ◽  
Inotropic State ◽  
End Diastolic Volume ◽  
State Compliance ◽  
Slope Change

The mean left ventricular pressure-flow relationship (Pv-Fv), determined under a constant preload and variable peripheral resistance, has been proposed as a quantitative representation of ventricular pump function (9). We determined the Pv-Fv relation in seven isolated cross-perfused canine hearts by varying resistance of a simulated arterial load in five steps from 6.0 to 0.375 mmHg X s X ml-1 while keeping end-diastolic volume, inotropic state, compliance, and characteristic impedance at various constant values. All of the 27 Pv-Fv relations thus determined were moderately nonlinear. Varying end-diastolic volume at three levels shifted the relation curve in an approximately parallel fashion (P less than 0.0001). At three levels of inotropic state (mean LVP of isovolumic contractions 34.3 +/- 8.2, 48.0 +/- 6.3, and 59.2 +/- 9.6 mmHg), the Pv-Fv relation shifted with predominantly a slope change (P less than 0.0001). Changing compliance at three levels (0.2, 0.4, and 0.8 ml/mmHg) caused a statistically significant but quantitatively small crossover of the Pv-Fv curves (P less than 0.0001). Changing characteristic impedance to 0.1, 0.2, and 0.4 mmHg X s X ml-1 caused a highly significant (P less than 0.0001) divergence of Pv-Fv relation over the high Fv range. We conclude that this sensitivity of the Pv-Fv relation to characteristic impedance limits its use as a contractility index.

scholarly journals Analysis and Application of Screens for Acoustic Impedance in a Speaker Box with a Passive Radiator to Decrease Standing-Wave Influence

2020 ◽  
Vol 10 (3) ◽  
pp. 866
Author(s):  
Yuan-Wu Jiang ◽  
Dan-Ping Xu ◽  
Zhi-Xiong Jiang ◽  
Jun-Hyung Kim ◽  
Ki-Hong Park ◽  
...  
Keyword(s):  
Standing Wave ◽  
Acoustic Resonance ◽  
Experimental Result ◽  
Parameter Method ◽  
Analysis Tool ◽  
Analysis Method ◽  
The Finite Element Method ◽  
Lumped Parameter ◽  
Acoustic Domain ◽  
Lumped Parameter Method

Micro speakers are playing an increasingly important role with the development of multimedia devices. This study applies the lumped-parameter method, which uses an equivalent circuit to model the electromagnetic and mechanical domains. The acoustic domain is modeled using the finite element method. Based on the analysis tool, the use of a screen is analyzed, and the screen is designed to depress the acoustic resonance in the sound-pressure-level curve and improve the performance. The samples are fabricated, and the experiment verifies the analysis method. The experimental result shows that the peak and dip due to the standing wave are cancelled, and the frequency response is smooth when the screen is used.

A Simple Shear and Torsion-Free Beam Model for Multibody Dynamics

2017 ◽  
Vol 12 (5) ◽  
Author(s):  
Juan Carlos García Orden ◽  
Javier Cuenca Queipo
Keyword(s):  
Computer Animation ◽  
Axial Stiffness ◽  
Parameter Method ◽  
Beam Model ◽  
Nonlinear Dynamical ◽  
Lumped Parameter ◽  
Proposed Model ◽  
Space Mechanisms ◽  
Lumped Parameter Method ◽  
Free Beam

This paper describes a very simple beam model, amenable to be used in multibody applications, for cases where the effects of torsion and shear are negligible. This is the case of slender rods connecting different parts of many space mechanisms, models useful in polymer physics, computer animation, etc. The proposed new model follows a lumped parameter method that leads to a rotation-free formulation. Axial stiffness is represented by a standard nonlinear truss model, while bending is modeled with a force potential. Several numerical experiments are carried out in order to assess accuracy, which is usually the main drawback of this type of approach. Results reveal a remarkable accuracy in nonlinear dynamical problems, suggesting that the proposed model is a valid alternative to more sophisticated approaches.

Image-Based Modeling of Blood Flow in Human Coronary Arteries With and Without Bypass Grafts During Rest and Simulated Exercise

2008 ◽  
Author(s):  
Jessica Shih ◽  
Hyun Jin Kim ◽  
Charles A. Taylor
Keyword(s):  
Coronary Artery ◽  
Coronary Bypass ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Ventricular Pressure ◽  
Bypass Grafts ◽  
Heart Model ◽  
Intramyocardial Pressure ◽  
Image Based Modeling ◽  
Lumped Parameter

The number of patients with coronary artery disease continues to rise, with approximately 469,000 coronary bypass procedures in 2005 alone [1]. A priori knowledge of the flow features within the coronary vascular system could prove useful in predicting flow changes due to coronary bypass surgery. Image-based modeling and 3-D computational simulations could be used to compute flow and pressure in a patient-specific manner. However, modeling coronary flow requires knowledge of the intramyocardial pressure that compresses coronary vessels, resulting in decreased flow in systole and increased flow in diastole. Left ventricular pressure can provide an estimate to intramyocardial pressure, but the aortic pressure and left ventricular pressure must be coupled in systole when the aortic valve is open. Previously, we have developed a method to couple a lumped-parameter heart model to the inlet of a 3-D model to compute aortic and ventricular pressure [2]. In this study, we use the lumped-parameter heart model and computational fluid dynamics to calculate flow dynamics in a patient model with coronary artery bypass grafts.

scholarly journals Analysis and Design of Helmholtz Protector to Improve High-Frequency Response of Insert Earphone

2019 ◽  
Vol 9 (12) ◽  
pp. 2541 ◽  
Author(s):  
Yuan-Wu Jiang ◽  
Dan-Ping Xu ◽  
Zhi-Xiong Jiang ◽  
Jun-Hyung Kim ◽  
Sang-Moon Hwang
Keyword(s):  
Frequency Response ◽  
High Frequency ◽  
Experimental Result ◽  
Parameter Method ◽  
Analysis Tool ◽  
Analysis Method ◽  
Analysis And Design ◽  
High Frequency Response ◽  
Lumped Parameter ◽  
Lumped Parameter Method

With the development of multimedia devices, earphones are playing an increasingly important role. This article applies the lumped parameter method using an equivalent circuit to model the electromagnetic, mechanical, and acoustic domains of earphones. Then, parameters are determined according to the dimensions and material properties of earphone parts. On the basis of the analysis tool and determined parameters, a Helmholtz protector is analyzed and designed to improve the high-frequency response. Samples are fabricated, and the experiment verifies the analysis method. The experimental result shows that the peaks at 7 k and 10 k are decreased at 8.05 dB and 7.89 dB. The root means square value of SPL deviation compared with target curve decreased from 9.77 to 4.39. High-frequency response is improved by using the Helmholtz protector.

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