scholarly journals A Portable & Disposable Ultra-Low Velocity Flow Sensor from Bioinspired Hair-Like Microstructures

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 731 ◽  
Author(s):  
Harish Devaraj ◽  
Rajnish Sharma ◽  
Enrico Haemmerle ◽  
Kean Aw
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Modular Design ◽  
Measurement Range ◽  
Flow Sensor ◽  
Design Development ◽  
Low Velocity ◽  
Velocity Flow ◽  
Loop Feedback ◽  
Air Flow Velocity

We present, for the first time, the design, development and testing of a portable ultra-lowvelocity flow sensor with a disposable architecture for use in medical applications. 3Dmicroprintingtechnique was used to fabricate high aspect ratio microscopic hair-like structuresfrom conducting polymers, in particular, poly(3,4-ethylenedioxythiophene):polystyrene-sulfonate(PEDOT:PSS). These high aspect ratio micro-hairs are flexible and conductive that can respond toair flowing over them. A disposable and portable flow sensor with a modular design that allowstuning of measurement range was developed, for integration with an automated neonatalresuscitator to provide closed-loop feedback. The developed portable sensor architecture is capableof real-time indication of the air flow velocity range down to few millimeters/second.

scholarly journals High aspect ratio nanotubes assembled from macrocyclic iminium salts

2018 ◽  
Vol 115 (36) ◽  
pp. 8883-8888 ◽  
Author(s):  
Chao Sun ◽  
Meng Shen ◽  
Anton D. Chavez ◽  
Austin M. Evans ◽  
Xiaolong Liu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Modular Design ◽  
Chlorinated Solvents ◽  
Iminium Salts ◽  
Iminium Ions ◽  
Iminium Ion ◽  
Dynamics Simulations ◽  
Organic Nanotubes

One-dimensional nanostructures such as carbon nanotubes and actin filaments rely on strong and directional interactions to stabilize their high aspect ratio shapes. This requirement has precluded making isolated, long, thin organic nanotubes by stacking molecular macrocycles, as their noncovalent stacking interactions are generally too weak. Here we report high aspect ratio (>103), lyotropic nanotubes of stacked, macrocyclic, iminium salts, which are formed by protonation of the corresponding imine-linked macrocycles. Iminium ion formation establishes cohesive interactions that, in organic solvent (tetrahydrofuran), are two orders of magnitude stronger than the neutral macrocycles, as explained by physical arguments and demonstrated by molecular dynamics simulations. Nanotube formation stabilizes the iminium ions, which otherwise rapidly hydrolyze, and is reversed and restored upon addition of bases and acids. Acids generated by irradiating a photoacid generator or sonicating chlorinated solvents also induced nanotube assembly, allowing these nanostructures to be coupled to diverse stimuli, and, once assembled, they can be fixed permanently by cross-linking their pendant alkenes. As large macrocyclic chromonic liquid crystals, these iminium salts are easily accessible through a modular design and provide a means to rationally synthesize structures that mimic the morphology and rheology of carbon nanotubes and biological tubules.

scholarly journals High Aspect Ratio Nanotubes Assembled from Macrocyclic Iminium Salts

2018 ◽  
Author(s):  
Chao Sun ◽  
Meng Shen ◽  
Anton Davidovich Chavez ◽  
Austin Evans ◽  
Xiaolong Liu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Modular Design ◽  
Chlorinated Solvents ◽  
Iminium Salts ◽  
Iminium Ions ◽  
Iminium Ion ◽  
Dynamics Simulations ◽  
Organic Nanotubes

<p>One-dimensional nanostructures such as carbon nanotubes rely on strong and directional interactions that stabilize their high aspect ratio shapes from fracture. This requirement has precluded making isolated, long, thin organic nanotubes by stacking molecular macrocycles, as their noncovalent stacking interactions are generally too weak. Here we report high aspect ratio (>10<sup>3</sup>), lyotropic nanotubes of stacked, macrocyclic, iminium salts, which are formed by protonation of the corresponding imine-linked macrocycles. Iminium ion formation establishes cohesive interactions that are two orders-of-magnitude stronger than the neutral macrocycles, as estimated by molecular dynamics simulations. Nanotube formation stabilizes the iminium ions, which otherwise rapidly hydrolyze, and is reversed and restored upon addition of bases and acids. Acids generated by irradiating a photoacid generator or sonicating chlorinated solvents also induced nanotube assembly, allowing these nanostructures to be coupled to diverse stimuli, and, once assembled, they can be fixed permanently by crosslinking their pendant alkenes. As the largest, and the first macrocyclic chromonic liquid crystals, macrocyclic iminium salts are easily accessible through a modular design and provide a means to rationally synthesize structures that mimic the morphology and rheology of carbon nanotubes and biological tubules.</p>

Effects of Aeroelastic Nonlinearity on Flutter and Limit Cycle Oscillations of High-Aspect-Ratio Wings

2011 ◽  
Vol 110-116 ◽  
pp. 4297-4306 ◽  
Author(s):  
Keivan Eskandary ◽  
Morteza Dardel ◽  
Mohammad Hadi Pashaei ◽  
Abdol Majid Kani
Keyword(s):  
Aspect Ratio ◽  
Limit Cycle ◽  
High Aspect Ratio ◽  
Large Deflection ◽  
Limit Cycle Oscillation ◽  
Low Velocity ◽  
Wing Model ◽  
Structural Nonlinearities ◽  
Cycle Oscillation ◽  
Compressibility Effects

In this study aeroelastic characteristics of long high aspect ratio wing models with structural nonlinearities in quasi-steady aerodynamics flows are investigated. The studied wing model is a cantilever wing with double bending and torsional vibrations and with large deflection ability in according to Dowell-Hodges wing model. This wing model is valid for long, straight and thin homogeneous isotropic beams. Aerodynamics model is based on quasi-steady aerodynamic which is valid for aerodynamic flows in low velocity and without wake, viscosity and compressibility effects. The effect of different parameters such as mass ratios and stiffness ratios on flutter and divergence velocities and limit cycle oscillation amplitudes are carefully studied.

scholarly journals High Aspect Ratio Nanotubes Assembled from Macrocyclic Iminium Salts

2018 ◽  
Author(s):  
Chao Sun ◽  
Meng Shen ◽  
Anton Davidovich Chavez ◽  
Austin Evans ◽  
Xiaolong Liu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Modular Design ◽  
Chlorinated Solvents ◽  
Iminium Salts ◽  
Iminium Ions ◽  
Iminium Ion ◽  
Dynamics Simulations ◽  
Organic Nanotubes

<p>One-dimensional nanostructures such as carbon nanotubes rely on strong and directional interactions that stabilize their high aspect ratio shapes from fracture. This requirement has precluded making isolated, long, thin organic nanotubes by stacking molecular macrocycles, as their noncovalent stacking interactions are generally too weak. Here we report high aspect ratio (>10<sup>3</sup>), lyotropic nanotubes of stacked, macrocyclic, iminium salts, which are formed by protonation of the corresponding imine-linked macrocycles. Iminium ion formation establishes cohesive interactions that are two orders-of-magnitude stronger than the neutral macrocycles, as estimated by molecular dynamics simulations. Nanotube formation stabilizes the iminium ions, which otherwise rapidly hydrolyze, and is reversed and restored upon addition of bases and acids. Acids generated by irradiating a photoacid generator or sonicating chlorinated solvents also induced nanotube assembly, allowing these nanostructures to be coupled to diverse stimuli, and, once assembled, they can be fixed permanently by crosslinking their pendant alkenes. As the largest, and the first macrocyclic chromonic liquid crystals, macrocyclic iminium salts are easily accessible through a modular design and provide a means to rationally synthesize structures that mimic the morphology and rheology of carbon nanotubes and biological tubules.</p>

Study of the Velocity Flow Field Under Distorted Inflow Conditions for a High Aspect Ratio Low Speed Contra Rotating Fan

2013 ◽  
Author(s):  
Chetan S. Mistry ◽  
A. M. Pradeep
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Total Pressure ◽  
Flow Behavior ◽  
Low Speed ◽  
Inlet Distortion ◽  
Velocity Magnitude ◽  
Velocity Flow ◽  
Design Speed ◽  
Inflow Conditions

In this paper, results from an experimental study on the effect of circumferential inflow distortion on the flow behavior of a high aspect ratio, low speed contra rotating fan, are reported. The total pressure at the inlet is artificially distorted by means of (i) 90° sector mesh having porosity of 0.70, (ii) 90° sector mesh having porosity combination of 0.70 and 1/3rd section at the hub region covered by mesh of porosity 0.64 (hub covered combined distortion) and (iii) 90° sector mesh having porosity combination of 0.7 and 1/3rd section at the tip region covered by mesh of porosity 0.64 (tip covered combined distortion). Detailed flow analyses were conducted under design speed combination and design mass flow rate of 6 kg/s. In order to understand the extent of inlet distortion, the distortion sector was rotated circumferentially at intervals of 15° to cover the entire annulus. Detailed measurements of velocity components and flow angles were carried out at the inlet of the first rotor, between the two rotors and at the exit of the second rotor. The study reveals a few interesting aspects on the effect of circumferential and combined distortion inflow distortion on the flow behavior of a contra-rotating stage. The presence of low porosity screen reduces the axial velocity magnitude and generates higher spread of distortion near the localized region of placement of the screen. The pure circumferential distortion has a greater effect on the performance of both the rotors compared to hub and tip covered combined distortion.

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