High-Speed Biaxial Tissue Properties of the Human Cadaver Aorta

2005 ◽  
Author(s):  
Chirag S. Shah ◽  
Matthew J. Mason ◽  
King H. Yang ◽  
Warren N. Hardy ◽  
Chris A. Van Ee ◽  
...  
Keyword(s):  
High Speed ◽  
Nonlinear Behavior ◽  
Longitudinal Direction ◽  
Traumatic Rupture ◽  
Tissue Properties ◽  
Automobile Crashes ◽  
Human Cadavers ◽  
Causes Of Mortality ◽  
Constitutive Representation ◽  
Automotive Crashes

Traumatic rupture of the aorta (TRA) is one of the leading causes of mortality in automobile crashes. Finite element (FE) modeling, used in conjunction with laboratory experiments, has emerged as increasingly important tool to understand the mechanisms of TRA. Appropriate material modeling of the aorta is a key aspect of such efforts. The current study focuses on obtaining biaxial mechanical properties of aorta tissue at strain rates typically experienced during automotive crashes. Five descending thoracic aorta samples from human cadavers were harvested in a cruciate shape. The samples were subjected to equibiaxial stretch at a strain rate of 44 s−1 using a new biaxial tissue-testing device. Inertially compensated loads were measured. High-speed videography was used to track ink dots marked on the center of each sample to obtain strain. The aorta tissue exhibited anisotropic and nonlinear behavior. The tissue was stiffer in the circumferential direction with a modulus of 10.64 MPa compared to 7.94 MPa in longitudinal direction. The peak stresses along the circumferential and longitudinal directions were found to be 1.89 MPa and 1.76 MPa, respectively. The tissue behavior can be used to develop a better constitutive representation of the aorta, which can be incorporated into FE models of the aorta.

A New Device for High-Speed Biaxial Tissue Testing: Application to Traumatic Rupture of the Aorta

2005 ◽  
Author(s):  
Matthew J. Mason ◽  
Chirag S. Shah ◽  
Muralikrishna Maddali ◽  
King H. Yang ◽  
Warren N. Hardy ◽  
...  
Keyword(s):  
High Speed ◽  
Traumatic Rupture ◽  
New Device

A study of modeling experiments of the vibration behavior of elevated railway box girder

2018 ◽  
Vol 25 (5) ◽  
pp. 984-995 ◽  
Author(s):  
Kun Luo ◽  
Xiaoyan Lei
Keyword(s):  
High Speed ◽  
Similarity Theory ◽  
Longitudinal Direction ◽  
Calculation Model ◽  
Scale Model ◽  
Box Girder ◽  
Vibration Transmissibility ◽  
Girder Bridge ◽  
Structure Simplification ◽  
Model Similarity

Based on the model similarity theory, this article deduces the model similarity relationship of the elevated railway box girder at the elastic stage and designs a 1/10 box girder scale model by adopting a 32 m simply-supported box girder bridge from the Beijing–Shanghai Railway as the prototype. It then verifies the validity of the model design and the dynamic similarity between the 1/10 model and the prototype through constraint mode and free mode experiments on the 1/10 scale model, together with transient finite element calculation. The dynamic calculation model is utilized here for the analysis of the errors occurring in the production of the model, and the effect of the model structure simplification on the box girder mode frequency and vibration response. Finally, the article studies the vibration transmissibility characteristics between the plates and along the longitudinal direction by means of model testing. It also discusses the effect of different bridge support stiffness on the box girder vibration. The results presented in this paper can provide a method for forecasting and evaluating the existing or plan-to-build high speed railway environment vibration.

Dynamic Modeling and Simulation of Short-Duration Over-excitation Phenomenon in Hysteresis Motor

2017 ◽  
Vol 8 (2) ◽  
pp. 623
Author(s):  
Sayyed Hossein Edjtahed ◽  
Amir Hossein Pir Zadeh ◽  
Abolfazl Halavaei Niasar
Keyword(s):  
Dynamic Model ◽  
Short Duration ◽  
Dynamic Modeling ◽  
High Speed ◽  
Nonlinear Behavior ◽  
Permanent Magnet Synchronous Motors ◽  
Small Power ◽  
Modeling And Analysis ◽  
Synchronous Motors ◽  
Terminal Voltage

The hysteresis motor is a well-known synchronous motor that is used in special small power, high speed applications. Dynamic modeling and analysis of this motor is more complicated than permanent magnet synchronous motors (PMSMs) or induction motors (IMs) due to nonlinear behavior of rotor magnetic material. Short over-excitation is a unique phenomenon that only occurs in hysteresis motor in which the terminal voltage increase at synchronous speed for a short duration, and then continuously is decrease to initial value. Therefore, the input current is reduced, this leads to more power factor and efficiency enhancement. Till now, there isn’t any analytic dynamic model of this phenomenon. In this paper, based on a novel dynamic model of hysteresis motor, the over-excitation phenomenon is investigated and transient performance of the motor during over-excitation is simulated via Simulink.

Near Side Lateral Impacts and Aortic Injury: A Parametric Study

2011 ◽  
Author(s):  
Aditya Belwadi ◽  
King H. Yang
Keyword(s):  
Head Injury ◽  
Cause Of Death ◽  
High Speed ◽  
Motor Vehicle ◽  
Flail Chest ◽  
The United States ◽  
Aortic Injury ◽  
Blunt Injury ◽  
Traumatic Rupture ◽  
Sternal Fracture

Traumatic rupture of the aorta (TRA) remains the second most common cause of death associated with motor vehicle crashes after brain injury. On an average, nearly 8,000 people die annually in the United States due to blunt injury to the aorta. It is observed that more than 80% of occupants who suffer an aortic injury die at the scene due to exsanguination into the chest cavity. TRA and blunt aortic injury (BAI) are leading causes of death in high-speed blunt impact trauma. More specific injuries that fall under these classifications include myocardial contusion (MC), traumatic aortic disruption (TAD), sternal fracture (SF), flail chest (FC) and tracheobronchial disruption (TBD) (Swan et al. 2001). Smith and Chang (1986) reported on 387 cases of blunt traumatic death in vehicular crashes and found that aortic injury was second only to head injury as the leading cause of death. Burkhart et al. (2001) reviewed 242 autopsy cases with fatal BAI and concluded that in most cases aortic injury was accompanied by head injury, rib fractures and/or hepatic trauma.

On The Steady State and Dynamic Performance Characteristics of Floating Ring Bearings

1981 ◽  
Vol 103 (3) ◽  
pp. 389-397 ◽  
Author(s):  
Chin-Hsiu Li ◽  
S. M. Rohde
Keyword(s):  
Steady State ◽  
Linear Theory ◽  
High Speed ◽  
Dynamic Performance ◽  
Equations Of Motion ◽  
Nonlinear Behavior ◽  
Journal Bearings ◽  
Transient Problem ◽  
The Stability ◽  
Bearing System

An analysis of the steady state and dynamic characteristics of floating ring journal bearings has been performed. The stability characteristics of the bearing, based on linear theory, are given. The transient problem, in which the equations of motion for the bearing system are integrated in real time was studied. The effect of using finite bearing theory rather than the short bearing assumption was examined. Among the significant findings of this study is the existence of limit cycles in the regions of instability predicted by linear theory. Such results explain the superior stability characteristics of the floating ring bearing in high speed applications. An understanding of this nonlinear behavior, serves as the basis for new and rational criteria for the design of floating ring bearings.

scholarly journals Nonlinear terahertz effects of gold nanofilms

2021 ◽  
Vol 14 (1) ◽  
pp. 20-30
Author(s):  
Peidi Yang ◽  
Baolong Zhang ◽  
Jinglong Ma ◽  
Yutong Li ◽  
Jungang Miao ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
High Speed ◽  
Strong Field ◽  
Nonlinear Behavior ◽  
Nonlinear Effects ◽  
Tunneling Effect ◽  
High Resistivity ◽  
New Paradigm ◽  
Terahertz Waves ◽  
Hybrid Substrates

Nonlinear interaction between strong-field terahertz electromagnetic waves and matters will become one of the next hot research frontiers in nonlinear optics. However, the lack of strong terahertz radiation sources and appropriate nonlinear terahertz materials have impeded its progress. Here we systematically have investigated the strong-field terahertz nonlinear effects of gold (Au) nanofilms on different substrates, including SiO2, high-resistivity Si and SiO2-high-resistivity Si hybrid substrates. The strong-field terahertz waves are emitted from lithium niobate crystals via tilted pulse front technique, and obvious nonlinear transmission responses are observed along with varying the incident field strengths for all the Au samples on the three types of the substrates. The nonlinear behavior is enhanced when the gold nanofilm thickness increases, which can be qualitatively understood by introducing the quantum tunneling effect and carrier multiplication theory generated at the Au nano-slits under the illumination of the strong-field terahertz pulses. Our demonstrations not only open a new paradigm for nonlinear terahertz investigations and future high-speed terahertz devices, but also provide an effective platform for exploring extreme terahertz sciences.

Planing force identification in high-speed underwater vehicles

2016 ◽  
Vol 22 (20) ◽  
pp. 4176-4191 ◽  
Author(s):  
Mojtaba Mirzaei ◽  
Mohammad Eghtesad ◽  
Mohammad Mahdi Alishahi
Keyword(s):  
High Speed ◽  
Hybrid Control ◽  
Equations Of Motion ◽  
Nonlinear Behavior ◽  
Underwater Vehicles ◽  
The Body ◽  
Force Identification ◽  
Control Approach ◽  
Control Scheme ◽  
Highly Nonlinear

One of the most important issues, which high-speed underwater vehicles (HSUV) deal with, is the so-called planing force. The dynamic of HSUV includes two separate phases called planing phase and non-planing phase. Ideally, in perfect flight, the vehicle should fly within the cavity walls. However, in practice, the vehicle impacts on the cavity boundaries due to disturbances. The magnitude of the planing force is large and has a strong effect on dynamics of HSUV. However, planing force modeling is often too simple and therefore inaccurate, due to the nonlinear interaction among the solid, liquid, and gaseous phases, which is not well understood yet. Consequently, planing force identification is of great importance and should be studied in details. The present paper discusses the identification of the planing force in HSUV. For this purpose, the equations of motion are developed for the HSUV in the planing phase while the tail and the body end impact on the cavity wall. Then, a robust hybrid switching control approach is employed to deal with the highly nonlinear behavior of the underwater vehicle as it is influenced by the liquid-gas boundary interactions. An on-line planing force identification based on Lyapunov function is considered within designing controller procedure, thus the stability of the system is guaranteed. Lateral and longitudinal planing force identification are achieved and discussed. Compared to the proportional-integral-derivative control scheme, the hybrid control scheme seems to increase the stabilization of HSUV, which is useful in avoiding unsteady changes of cavity shape.

scholarly journals Morphology, Hardness and Wear Properties of Plasma Cladding NiCrCu Coating on M2 High-Speed Steel

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 641 ◽  
Author(s):  
Shengwei Zhang ◽  
Min Lei ◽  
Mingpan Wan ◽  
Chaowen Huang
Keyword(s):  
Wear Resistance ◽  
High Speed ◽  
High Speed Steel ◽  
Longitudinal Direction ◽  
Wear Properties ◽  
Cladding Layer ◽  
Plasma Cladding ◽  
M2 High Speed Steel ◽  
Red Hardness ◽  
Composition Fluctuations

To improve the cutting performance, the red hardness and wear resistance of M2 high-speed steel, as well as expand the application field, in this work, a coating was fabricated via plasma cladding on M2 high-speed steel using Ni, Cr and Cu alloy elements as precursor materials. The distribution and composition of alloying elements, microhardness and wear resistance of the coating were studied. The results show that the NiCrCu cladding layer contains many types of carbides. The secondary hardening caused by the dispersion of carbides can significantly improve the hardness, red hardness and wear resistance of material. The hardness of cladding layer is above 950 HV, after holding at 600 °C for 4 h, the hardness is above 932 HV. The alloy elements are evenly distributed, but, due to the rapid solidification after the cladding, there are composition fluctuations in the longitudinal direction. The wear resistance of the cladding layer is excellent; the wear rate is reduced from 1.75 to 1.44 × 10−6 mm3 N−1 m−1 or less; and the wear mechanism is a combination of abrasive wear and adhesive wear.

scholarly journals Characteristics of fire in high-speed train carriages

2019 ◽  
Vol 38 (1) ◽  
pp. 75-95
Author(s):  
Haiquan Bi ◽  
Yuanlong Zhou ◽  
Honglin Wang ◽  
Qilin Gou ◽  
Xiaoxia Liu
Keyword(s):  
Numerical Simulation ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Ignition Temperature ◽  
High Speed ◽  
Rapid Development ◽  
Longitudinal Direction ◽  
High Speed Train ◽  
Fire Source

With the rapid development of high-speed railways, safety hazards presented by train fires cannot be ignored. An effective design for protection against fire in high-speed trains is essential to ensure passenger safety. In this study, the cone calorimeter and ignition temperature tester were used to carry out combustion experiments on materials constituting the main components of the train. The heat release rate, smoke yield, CO yield, and ignition temperature of combustible materials were tested. Based on the experimental data of material combustion, a numerical model of the high-speed train carriage fire was simulated. The accuracy of the numerical simulation was verified by drawing a comparison with the full-scale train fire experiment in existing literature. The numerical simulation results revealed that when the fire source is present at the corner of the carriage end door, the fire develops to the maximum possible extent in approximately 25 min, with a peak heat release rate of approximately 38.4 MW. Increase in the carriage fire heat release rate and breakage of windows occur almost simultaneously. Improvement of the fireproof performance of windows can inhibit and delay the carriage fire development. For the flashover of carriage fire, the spread speed of the flashover area in the longitudinal direction inside the carriage is approximately 1.9 m/s. The end door area furthest from the fire source in the carriage has strong flashover, while the flashover in other areas is weak.

scholarly journals Estimating Vocal Fold Contact Pressure from Raw Laryngeal High-Speed Videoendoscopy Using a Hertz Contact Model

2019 ◽  
Vol 9 (11) ◽  
pp. 2384 ◽  
Author(s):  
Manuel E. Díaz-Cádiz ◽  
Sean D. Peterson ◽  
Gabriel E. Galindo ◽  
Víctor M. Espinoza ◽  
Mohsen Motie-Shirazi ◽  
...  
Keyword(s):  
Contact Pressure ◽  
Video Processing ◽  
Vocal Fold ◽  
High Speed ◽  
Numerical Models ◽  
Objective Assessment ◽  
Direct Methods ◽  
Vocal Folds ◽  
Processing Technique ◽  
Tissue Properties

The development of trauma-induced lesions of the vocal folds (VFs) has been linked to a high collision pressure on the VF surface. However, there are no direct methods for the clinical assessment of VF collision, thus limiting the objective assessment of these disorders. In this study, we develop a video processing technique to directly quantify the mechanical impact of the VFs using solely laryngeal kinematic data. The technique is based on an edge tracking framework that estimates the kinematic sequence of each VF edge with a Kalman filter approach and a Hertzian impact model to predict the contact force during the collision. The proposed formulation overcomes several limitations of prior efforts since it uses a more relevant VF contact geometry, it does not require calibrated physical dimensions, it is normalized by the tissue properties, and it applies a correction factor for using a superior view only. The proposed approach is validated against numerical models, silicone vocal fold models, and prior studies. A case study with high-speed videoendoscopy recordings provides initial insights between the sound pressure level and contact pressure. Thus, the proposed method has a high potential in clinical practice and could also be adapted to operate with laryngeal stroboscopic systems.

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