scholarly journals Vacuum-Actuated Bending for Grasping

Robotics ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 73
Author(s):  
Jay Miller ◽  
Nathan Wicks
Keyword(s):  
Negative Pressure ◽  
Atmospheric Pressure ◽  
Ambient Pressure ◽  
Positive Pressure ◽  
Cellular Solids ◽  
Pressure Application ◽  
Bending Actuator ◽  
Robotic Devices ◽  
Good Agreement

Soft robotic devices typically are actuated with the application of a positive pressure (compared to ambient pressure), but some exciting work has been done with negative pressure application, with advantages for safety and robustness. Here, we present a negative pressure bending actuator inspired by previous work by Yang et al., fabricated using rapid prototyping techniques and elastomeric polymers. We describe the mechanical behavior of the system from a cellular solids perspective, showing the steps needed for the analysis and characterization of future similar systems. We find good agreement between experimentally measured values of displacement and force generated in atmospheric pressure conditions.

Effect of intrathoracic pressure on pressure-volume characteristics of the lung in man

1975 ◽  
Vol 38 (3) ◽  
pp. 411-417 ◽  
Author(s):  
H. S. Goldberg ◽  
W. Mitzner ◽  
K. Adams ◽  
H. Menkes ◽  
S. Lichtenstein ◽  
...  
Keyword(s):  
Negative Pressure ◽  
Total Lung Capacity ◽  
Human Subjects ◽  
Ambient Pressure ◽  
Intrathoracic Pressure ◽  
Dynamic Compliance ◽  
Positive Pressure ◽  
Lung Capacity ◽  
Airway Opening ◽  
Volume Characteristics

Quasi-static pressure-volume (P-V) curves in normal seated human subjects were determined with pressure at the airway opening (Pa0) set below (negative pressure), above (positive pressure), or equal to ambient pressure. Dynamic compliance (Cdyn) during controlled continuous negative pressure breathing (CNPB) was also studied. Quasi-static P-V curves at negative pressure were decreased in slope, reflected a decrease in total lung capacity, and intersected the P-V curve obtained at ambient Pa0. At positive pressure the P-V curves showed an increase in slope and an increase in total lung capacity. During CNPB a fall in Cdyn was found. The fall in Cdyn was rapid and persisted for the duration of CNPB. Cdyn promptly returned to control levels when Pa0 was adjusted to ambient pressure.

Effect of continuous pressure breathing on right ventricular volumes

1967 ◽  
Vol 22 (6) ◽  
pp. 1053-1060 ◽  
Author(s):  
Maylene Wong ◽  
Edgardo E. Escobar ◽  
Gilberto Martinez ◽  
John Butler ◽  
Elliot Rapaport
Keyword(s):  
Right Ventricular ◽  
Negative Pressure ◽  
Atmospheric Pressure ◽  
Diastolic Pressure ◽  
Venous Pressure ◽  
Intrathoracic Pressure ◽  
Transmural Pressure ◽  
Positive Pressure ◽  
End Diastolic Volume ◽  
Negative Pressure Breathing

We measured the end-diastolic volume (EDV) and stroke volume (SV) in the right ventricle of anesthetized dogs during continuous pressure breathing and compared them to measurements taken during breathing at atmospheric pressure. During intratracheal positive-pressure breathing, EDV, and SV decreased and end-diastolic pressure became more positive relative to atmospheric pressure. During intratracheal negative-pressure breathing, EDV enlarged and SV tended to increase; end-diastolic pressure became more negative. During extrathoracic negative-pressure breathing SV decreased, EDV fell, though not significantly, and end-diastolic pressure rose, but insignificantly. Changes in EDV observed during intratracheal positive-pressure breathing and intratracheal negative-pressure breathing were associated with minor shifts in transmural pressure (end-diastolic pressure minus intrapleural pressure) in the expected directions, but during extrathoracic negative-pressure breathing a large increase in transmural pressure took place with the nonsignificant reduction in EDV. We believe that intrathoracic pressure influences right ventricular filling by changing the peripheral-to-central venous pressure gradient. The cause of the alteration in diastolic ventricular distensibility demonstrated during extra-thoracic negative-pressure breathing remains unexplained. positive-pressure breathing; negative-pressure breathing; extrathoracic negative-pressure breathing Submitted on August 16, 1966

Effect of increases in lung volume on clearance of aerosolized solute from human lungs

1985 ◽  
Vol 59 (4) ◽  
pp. 1242-1248 ◽  
Author(s):  
J. D. Marks ◽  
J. M. Luce ◽  
N. M. Lazar ◽  
J. N. Wu ◽  
A. Lipavsky ◽  
...  
Keyword(s):  
Lung Volume ◽  
Negative Pressure ◽  
Ambient Pressure ◽  
Pressure Control ◽  
Positive Pressure ◽  
Healthy Humans ◽  
Human Lungs ◽  
Solute Uptake ◽  
Residual Capacity ◽  
Negative Pressure Breathing

To study the effect of increases in lung volume on solute uptake, we measured clearance of 99mTc-diethylenetriaminepentaacetic acid (Tc-DTPA) at different lung volumes in 19 healthy humans. Seven subjects inhaled aerosol (1 micron activity median aerodynamic diam) at ambient pressure; clearance and functional residual capacity (FRC) were measured at ambient pressure (control) and at increased lung volume produced by positive pressure [12 cmH2O continuous positive airway pressure (CPAP)] or negative pressure (voluntary breathing). Six different subjects inhaled aerosol at ambient pressure; clearance and FRC were measured at ambient pressure and CPAP of 6, 12, and 18 cmH2O pressure. Six additional subjects inhaled aerosol at ambient pressure or at CPAP of 12 cmH2O; clearance and FRC were determined at CPAP of 12 cmH2O. According to the results, Tc-DTPA clearance from human lungs is accelerated exponentially by increases in lung volume, this effect occurs whether lung volume is increased by positive or negative pressure breathing, and the effect is the same whether lung volume is increased during or after aerosol administration. The effect of lung volume must be recognized when interpreting the results of this method.

Cavitation in Negative-pressure Microcapillary Devices with Tapered Constrictions: Experiment and Numerical Simulation

2012 ◽  
Vol 13 (5) ◽  
Author(s):  
Xing Yang ◽  
Jiang Li ◽  
Haosheng Chen
Keyword(s):  
Numerical Simulation ◽  
Negative Pressure ◽  
Atmospheric Pressure ◽  
Microfluidic Devices ◽  
Cavitation Number ◽  
Experimental Results ◽  
Positive Pressure ◽  
Pressure System ◽  
Recirculation Flow ◽  
Simulation Results

AbstractMicrocapillary devices with tapered constrictions were fabricated for the study of the features of the cavitation. The cavitation was induced by applying negative pressure at the outlet with opening the inlet to atmospheric pressure, and the experimental results show that the cavitation bubbles generated at the center of the tapered tip flow upstream and adhere on the wall near the orifice, which is explained by the recirculation flow according to the numerical simulation results. The desinent cavitation number keeps constant for a microcapillary device, and the device works in a negative-pressure system is more susceptible to the cavitation than that works in a positive-pressure system. In addition, the effect of the orifice size on the incipient cavitation number and the desinent cavitation number has been studied with five devices with different sizes of the orifices from 50 to 120 microns. Both the incipient and desinent cavitation numbers increase monotonely with the size of the orifice. These results may be helpful to the design of the geometries of the microfluidic devices for various applications.

Experimental Characterization of Flow Regimes for a Rotating Disc Over a Range of Gas Pressures

2013 ◽  
Author(s):  
Tathagata Acharya ◽  
Jordan Falgoust ◽  
Michael J. Martin ◽  
Richard E. Rasmussen
Keyword(s):  
Atmospheric Pressure ◽  
Ambient Pressure ◽  
Characteristic Dimension ◽  
Viscous Drag ◽  
Frictional Torque ◽  
Experimental Setup ◽  
Experimental Characterization ◽  
Rotating Disc ◽  
Gas Pressures

Experimental measurement of viscous drag is done on a rotating disc using a disc spin-down experiment in various air pressures ranging from atmospheric pressure through a vacuum pressure of 0.3 kPa. The torque is non-dimensionalized using the dynamic viscosity of air, angular velocity, and the characteristic dimension of the disc. The results can be classified as two different sets. Between atmospheric pressure and 13.3 kPa, the curves have a vertical downward trend and are connected to each other while at lower pressures the curves appear to be more horizontal. It is shown that the present experimental setup is an improvement over the old setup because the frictional torque associated with the experiment has been reduced by 25 % approximately, and the ambient pressure reached in the chamber is a fourth of the ultimate pressure reached before.

Electron microscope characterization of MOCVD-grown gap layers on Si

1986 ◽  
Vol 44 ◽  
pp. 724-725
Author(s):  
K.M. Jones ◽  
M.M. Al-Jassim ◽  
J.M. Olson
Keyword(s):  
Atmospheric Pressure ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Organic Chemical ◽  
Lattice Match ◽  
Si Substrates ◽  
Metal Organic ◽  
Good Lattice ◽  
Antiphase Domains

The epitaxial growth of III-V semiconductors on Si for integrated optoelectronic applications is currently of great interest. GaP, with a lattice constant close to that of Si, is an attractive buffer between Si and, for example, GaAsP. In spite of the good lattice match, the growth of device quality GaP on Si is not without difficulty. The formation of antiphase domains, the difficulty in cleaning the Si substrates prior to growth, and the poor layer morphology are some of the problems encountered. In this work, the structural perfection of GaP layers was investigated as a function of several process variables including growth rate and temperature, and Si substrate orientation. The GaP layers were grown in an atmospheric pressure metal organic chemical vapour deposition (MOCVD) system using trimethylgallium and phosphine in H2. The Si substrates orientations used were (100), 2° off (100) towards (110), (111) and (211).

Characterization of Colloidal Amorphous Arrays Prepared by Uniaxial Pressure Application

Langmuir ◽  
2019 ◽  
Vol 35 (43) ◽  
pp. 13983-13990 ◽  
Author(s):  
Yui Naoi ◽  
Takahiro Seki ◽  
Ryosuke Ohnuki ◽  
Shinya Yoshioka ◽  
Yukikazu Takeoka
Keyword(s):  
Uniaxial Pressure ◽  
Pressure Application

scholarly journals Synthesis and characterization of analcime (ANA) zeolite using a kaolinitic rock

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daniela Novembre ◽  
Domingo Gimeno
Keyword(s):  
Ambient Pressure ◽  
Added Value ◽  
Emission Spectrometry ◽  
Quantitative Phase Analysis ◽  
Crystallization Time ◽  
Experimental Protocol ◽  
Economic Point ◽  
Cell Parameters ◽  
Synthesis Protocol

AbstractAnalcime is nowadays an important component in dental porcelain systems, in heterogeneous catalysis, in the nanoelectronic field, in selective adsorption and in stomatology (dental filling and prosthesis). Analcime synthesis from an impure, silica-rich kaolinite rock coming from Romana (Sassari, Italy) is here presented. A synthesis protocol is proposed that aims to make an improvement of synthesis conditions compared to the past. The hydrothermal treatment is in fact here achieved without aging times and without the use of sodium silicate or other additional silica source reported in the literature. Lower calcination temperature, synthesis temperature and crystallization time are verified in this work. The kaolin is subjected to calcination at the temperature of 650 °C and then mixed with NaOH. The experiment is performed at ambient pressure and 170 ± 0.1 °C. The degree of purity of analcime is calculated in 97.57% at 10 h. Analcime is characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, inductively coupled plasma optical emission spectrometry and thermal analysis. Density is also calculated. Cell parameters and the amount of amorphous phase in the synthesis powders is estimated with quantitative phase analysis using the combined Rietveld and reference intensity ratio methods. The experimental conditions make the synthesis protocol particularly attractive from an economic point of view. Also this work does not use a commercial kaolin but silica-rich impure kaolinitic rock from a disused quarry. This further reduces the costs of the experimental protocol. It also gives the protocol an added value, as the synthesis of a useful mineral is obtained through the valorization of an otherwise unused georesource. Both chemical and physical characterization of analcime is satisfactory making the experimental protocol very promising for an industrial transfer.

scholarly journals Characterization of Tiled Architecture for C-Band 1-Bit Beam-Steering Transmitarray

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1259
Author(s):  
Dmitry Kozlov ◽  
Irina Munina ◽  
Pavel Turalchuk ◽  
Vitalii Kirillov ◽  
Alexey Shitvov ◽  
...  
Keyword(s):  
Communication Systems ◽  
Beam Steering ◽  
Unit Cell ◽  
Electromagnetic Simulations ◽  
Fifth Generation ◽  
Full Wave ◽  
Array Architecture ◽  
Modulation Pattern ◽  
Good Agreement

A new implementation of a beam-steering transmitarray is proposed based on the tiled array architecture. Each pixel of the transmitarray is manufactured as a standalone unit which can be hard-wired for specific transmission characteristics. A set of complementary units, providing reciprocal phase-shifts, can be assembled in a prescribed spatial phase-modulation pattern to perform beam steering and beam forming in a broad spatial range. A compact circuit model of the tiled unit cell is proposed and characterized with full-wave electromagnetic simulations. Waveguide measurements of a prototype unit cell have been carried out. A design example of a tiled 10 × 10-element 1-bit beam-steering transmitarray is presented and its performance benchmarked against the conventional single-panel, i.e., unibody, counterpart. Prototypes of the tiled and single-panel C-band transmitarrays have been fabricated and tested, demonstrating their close performance, good agreement with simulations and a weak effect of fabrication tolerances. The proposed transmitarray antenna configuration has great potential for fifth-generation (5G) communication systems.

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