Simulated experiment on buckling blockage of trachea model using collapsible tube

Negative effort dependence (NED), decreased airflow despite increased driving pressure, has been proposed as a specific obstructive sleep apnea (OSA) phenotypic characteristic. We examined conditions under which NED occurs in a collapsible tube, pharyngeal airway bench model with the chamber enclosed, focusing on relationships with surrounding pressure levels and longitudinal strain. Using a vacuum source, graded airflows (V̇; 0–5 l/s) were generated through a thin-walled latex tube enclosed within a rigid, cylindrical chamber, sealed with initial chamber pressures (Pci) of 0–5 cmH2O (separate runs), or opened to the atmosphere. Upstream minus downstream pressure (Pu − Pd), maximum airflow (V̇max), and chamber pressure (Pc) were measured at 0–50% longitudinal strain. NED occurred across the range of Pci and strains studied but was most pronounced for the chamber open condition. With a sealed chamber, V̇ increased and Pc decreased with increasing Pu − Pd until the onset of NED at V̇max and a Pc value that was designated as critical (Pcc). Pcc was lowest (−17 cmH20) and V̇max was highest (~5 l/s) with chamber sealed: Pci = 0 cmH2O and 12.5 to 25% strain. We conclude that for our collapsible tube model, the achievable V̇max before the onset of NED depends on both the initial conditions (Pci and strain) and the dynamics of feedback between driving pressure and chamber pressure (chamber sealed vs. open). NED-based phenotypic analyses for OSA may need to focus on potential feedback control mechanisms (eg lung volume change, muscle activity) that may link peripharyngeal tissue pressure levels to driving pressures for airflow. NEW & NOTEWORTHY A collapsible tube, pharyngeal airway bench model was used to study the role of surrounding pressure and longitudinal wall strain at the onset of negative effort dependence (NED). NED occurred to varying degrees across all conditions tested, but maximum airflow was achieved with 1) low initial surrounding pressure, 2) a feedback mechanism between surrounding pressure and driving pressure; and 3) a moderate amount of strain applied. Potential impacts on OSA phenotypic analyses are discussed.

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Biomechanical evaluation and finite element analysis of axial-loading simulated experiment of wrist fracture

10.21203/rs.2.24404/v2 ◽

2020 ◽

Author(s):

Yuan-Wei Zhang ◽

Liang-Yu Xiong ◽

Zu-Tai Huang ◽

Xin Xiao ◽

Su-Li Zhang ◽

...

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Axial Loading ◽

Wrist Fracture ◽

Element Analysis ◽

Simulated Experiment ◽

Biomechanical Evaluation

Abstract The authors have withdrawn this preprint due to author disagreement.

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In COM we trust: Feasibility of USB-based event marking

Behavior Research Methods ◽

10.3758/s13428-021-01571-z ◽

2021 ◽

Author(s):

Stefan Appelhoff ◽

Tristan Stenner

Keyword(s):

Data Analysis ◽

Data Streams ◽

Cost Effective ◽

Computer Hardware ◽

Parallel Port ◽

Simulated Experiment ◽

Extensive Documentation ◽

Electrical Pulses ◽

Acquisition Device ◽

Data Acquisition Device

AbstractModern experimental research often relies on the synchronization of different events prior to data analysis. One way of achieving synchronization involves marking distinct events with electrical pulses (event markers or “TTL pulses”), which are continuously recorded with research hardware, and can later be temporally aligned. Traditionally, this event marking was often performed using the parallel port in standard personal computers. However, the parallel port is disappearing from the landscape of computer hardware, being replaced by a serial (COM) port, namely the USB port. To find an adequate replacement for the parallel port, we evaluated four microcontroller units (MCUs) and the LabJack U3, an often-used USB data acquisition device, in terms of their latency and jitter for sending event markers in a simulated experiment on both Windows and Linux. Our results show that all four MCUs were comparable to the parallel port in terms of both latency and jitter, and consistently achieved latencies under 1 ms. With some caveats, the LabJack U3 can also achieve comparable latencies. In addition to the collected data, we share extensive documentation on how to build and use MCUs for event marking, including code examples. MCUs are a cost-effective, flexible, and performant replacement for the disappearing parallel port, enabling event marking and synchronization of data streams.

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Oscillations in a Collapsed-Tube Analog of the Brachial Artery Under a Sphygmomanometer Cuff

Journal of Biomechanical Engineering ◽

10.1115/1.3168364 ◽

1989 ◽

Vol 111 (3) ◽

pp. 185-191 ◽

Cited By ~ 19

Author(s):

C. D. Bertram ◽

C. J. Raymond ◽

K. S. A. Butcher

Keyword(s):

High Frequency ◽

Flow Characteristics ◽

Low Frequency ◽

Collapsible Tube ◽

Tube Size ◽

Low Frequency Oscillations ◽

Central Segment ◽

Experimental Parameters ◽

Aqueous Flow ◽

Low Frequency Mode

To determine whether self-excited oscillations in a Starling resistor are relevant to physiological situations, a collapsible tube conveying an aqueous flow was externally pressurized along only a central segment of its unsupported length. This was achieved by passing the tube through a shorter and wider collapsible sleeve which was mounted in Starling resistor fashion in a pressure chamber. The tube size and material, and all other experimental parameters, were as used in our previous Starling resistor studies. Both low- and high-frequency self-excited oscillations were observed, but the low-frequency oscillations were sensitive to the sleeve type and length relative to unsupported distance. Pressure-flow characteristics showed multiple oscillatory modes, which differed quantitatively from those observed in comparable Starling resistors. Slow variation of driving pressure gave differing behavior according to whether the pressure was rising or falling, in accord with the hysteresis noted on the characteristics and in the tube law. The results are discussed in terms of the various possible mechanisms of collapsible tube instability, and reasons are presented for the absence of the low-frequency mode under most physiological circumstances.

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SOME ANALYSIS ON THE COLLAPSIBLE TUBE-JET SYSTEM

Frontiers of Fluid Mechanics ◽

10.1016/b978-0-08-036232-8.50182-1 ◽

1988 ◽

pp. 1023-1028

Author(s):

Wang Yaping ◽

Liu Zhaorong

Keyword(s):

Collapsible Tube

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An Optimized HT-Based Method for the Analysis of Inter-Area Oscillations on Electrical Systems

Energies ◽

10.3390/en12152935 ◽

2019 ◽

Vol 12 (15) ◽

pp. 2935 ◽

Cited By ~ 3

Author(s):

Francesco Bonavolontà ◽

Luigi Pio Di Noia ◽

Davide Lauria ◽

Annalisa Liccardo ◽

Salvatore Tessitore

Keyword(s):

Phasor Measurement Unit ◽

Measurement Unit ◽

Frequency Interval ◽

Electrical System ◽

Characteristic Parameters ◽

Electrical Systems ◽

Electromechanical Oscillations ◽

Simulated Experiment ◽

Novel Method ◽

The Individual

The paper deals with a novel method to measure inter-area oscillations, i.e., electromechanical oscillations involving groups of generators geographically distant from one another and ranging within the frequency interval from 0.1 Hz up to 1 Hz. The estimation of the parameters characterizing inter-area oscillations is a crucial objective in order to take the necessary actions to avoid the instability of the transmission electrical system. The proposed approach is a signal-based method, which uses samples of electrical signals acquired by the phasor measurement unit (PMU) and processes them to extract the individual oscillations and, for each of them, determine their characteristic parameters such as frequency and damping. The method is based on Hilbert transformations, but it is optimized through further algorithms aiming at (i) improving the ability to separate different oscillatory components, even at frequencies very close to each other, (ii) enhancing the accuracy associated with the damping estimates of each oscillation, and (iii) increasing the robustness to the noise affecting the acquired signal. Results obtained in the presence of signals involving the composition of two oscillations, whose damping and frequency have been varied, are presented. Tests were conducted with signals either synthesized in simulated experiment or generated and acquired with actual laboratory instrumentation.

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