Proppant Transport Characterization of Hydraulic-Fracturing Fluids Using a High-Pressure Simulator Integrated With a Fiber-Optic/Light-Emitting-Diode (LED) Vision System

2001 ◽  
Vol 16 (01) ◽  
pp. 42-49 ◽  
Author(s):  
Subhash N. Shah ◽  
Asadi Mahmoud ◽  
David L. Lord
Keyword(s):  
High Pressure ◽  
Hydraulic Fracturing ◽  
Fiber Optic ◽  
Vision System ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
Proppant Transport ◽  
Fracturing Fluids

Remote Fiber-Optic Flow Cell for the Detection of Uranium(VI) in Groundwater

2002 ◽  
Vol 56 (4) ◽  
pp. 464-468 ◽  
Author(s):  
Greg E. Collins ◽  
Qin Lu ◽  
Sitra Abubeker ◽  
Elizabeth Vajs
Keyword(s):  
Metal Ion ◽  
Fiber Optic ◽  
Light Emitting Diode ◽  
Red Light ◽  
Arsenazo Iii ◽  
Reagent Solution ◽  
Light Emitting ◽  
Low Levels ◽  
Exchange Membrane

Optimization and initial characterization of a remote probe for extremely low levels (<20 μg/L) of uranium(VI) in groundwater are described. The monitor takes advantage of a small length of Nafion cation exchange membrane tubing, which permits diffusion of the uranyl ion into an internally renewable reagent solution of Arsenazo III. The sensitive, colorimetric metal complexation of uranium(VI) by Arsenazo III is measured by recording the absorbance change in a fiber-optic SMA Z-cell that is coupled to a red-light-emitting diode. The entire system is packaged on a 2 × 11 in. breadboard and attached to a 100-ft power and data transmission cord. The final optimized pH of 1.5 was utilized for maximizing sensitivity to uranium while minimizing interferences from other metal ion impurities. The addition of 1 mM diethylenetriaminepentaacetic acid to the reagent further assisted in the elimination of metal ion interferences. Two Nafion membrane tubings with different internal diameters and wall thicknesses are evaluated. Using a 20 min diffusion time and the Nafion 20 membrane, the detection limit obtained for uranium(VI) in groundwater was 1.4 ppb. Of the twenty metal ion interferents examined, all gave essentially no response, with the exception of calcium and thorium, for which a 30 mg/L and a 100 μg/L solution, respectively, gave signals representative of 4.7 and 6.0 ppb uranium(VI).

Characterization and Elimination of Forward Snapback Defects in GaAs Light Emitting Diodes

1996 ◽  
Author(s):  
J. Zimmer ◽  
D. Nielsen ◽  
T.A. Anderson ◽  
M. Schade ◽  
N. Saha ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Light Emitting Diode ◽  
Elevated Concentration ◽  
Forward Voltage ◽  
Light Emitting ◽  
Intermittent Yield ◽  
Si Doped ◽  
Secondary Ion ◽  
Furnace Pressure

Abstract The p-n junction of a GaAs light emitting diode is fabricated using liquid phase epitaxy (LPE). The junction is grown on a Si doped (~1018/cm3) GaAs substrate. Intermittent yield loss due to forward voltage snapback was observed. Historically, out of specification forward voltage (Vf) parameters have been correlated to abnormalities in the junction formation. Scanning electron (SEM) and optical microscopy of cleaved and stained samples revealed a continuous layer of material approximately 2.5 to 3.0 urn thick at the n-epi/substrate interface. Characterization of a defective wafer via secondary ion mass spectroscopy (SIMS) revealed an elevated concentration of O throughout the region containing the defect. X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) data taken from a wafer prior to growth of the epi layers did not reveal any unusual oxidation or contamination. Extensive review of the processing data suggested LPE furnace pressure was the obvious source of variability. Processing wafers through the LPE furnace with a slight positive H2 gas pressure has greatly reduced the occurrence of this defect.

scholarly journals Implantable Optrode Array for Optogenetic Modulation and Electrical Neural Recording

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 725
Author(s):  
Saeyeong Jeon ◽  
Youjin Lee ◽  
Daeho Ryu ◽  
Yoon Kyung Cho ◽  
Yena Lee ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Neural Recording ◽  
Electrophysiological Recording ◽  
Light Emitting ◽  
Technological Advances ◽  
Neuroscience Research ◽  
Cell Type Specific ◽  
Novel Design

During the last decade, optogenetics has become an essential tool for neuroscience research due to its unrivaled feature of cell-type-specific neuromodulation. There have been several technological advances in light delivery devices. Among them, the combination of optogenetics and electrophysiology provides an opportunity for facilitating optogenetic approaches. In this study, a novel design of an optrode array was proposed for realizing optical modulation and electrophysiological recording. A 4 × 4 optrode array and five-channel recording electrodes were assembled as a disposable part, while a reusable part comprised an LED (light-emitting diode) source and a power line. After the characterization of the intensity of the light delivered at the fiber tips, in vivo animal experiment was performed with transgenic mice expressing channelrhodopsin, showing the effectiveness of optical activation and neural recording.

Design, Measurements and Characterization of Smart Electronic Board for PV Streetlight based on LED and High Intensity Discharge Lamps

2013 ◽  
pp. 153-165
Author(s):  
Paolo Visconti ◽  
Daniele Romanello ◽  
Giovanni Zizzari ◽  
Vito Ventura ◽  
Giorgio Cavalera
Keyword(s):  
Rural Areas ◽  
High Intensity ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
Electronic Board ◽  
Lighting Systems ◽  
And Control ◽  
Near Future ◽  
Hid Lamps

This work presents an electronic board for driving and control of High Intensity Discharge (HID) lamps and Light Emitting Diode (LED) lamps. The proposed electronic board is able to drive HID or LED lamps by means of a reconfigurable output. This feature allows using the ballast in lighting systems that currently use traditional discharge lamps, as well as keeping the same ballast when discharge lamps are replaced by LED modules in the near future, when LED street lighting systems will be more affordable. Additionally, since the lighting system is designed to be used in rural areas where there is no public electricity, each lighting point incorporates a system to convert solar energy into continuous voltage by means of photovoltaic panels. In this work, energy saving issues are taken into account.

scholarly journals Fabrication and Characterization of Light Emitting Diode Based on n-ZnO Nanorods Grown Via a Low-Temperature

2020 ◽  
Vol 1535 ◽  
pp. 012009
Author(s):  
Sabah M. Mohammad ◽  
Nabeel M. Abd-Alghafour ◽  
Z. Hassan ◽  
Naser M. Ahmed ◽  
Amal Mohamed Ahmed Ali ◽  
...  
Keyword(s):  
Low Temperature ◽  
Light Emitting Diode ◽  
Zno Nanorods ◽  
Light Emitting ◽  
Fabrication And Characterization
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