A new device for highly accurate gas flow control with extremely fast response times

2011 ◽  
Author(s):  
Kevin Boyd ◽  
Adam Monkowski ◽  
Jialing Chen ◽  
Tao Ding ◽  
Ray Malone ◽  
...  
Keyword(s):  
Flow Control ◽  
Gas Flow ◽  
Response Times ◽  
Fast Response ◽  
New Device

Nanostructure of semiconductor quantum dots in a borosilicate glass matrix by complementary use of HREM and AEM

1990 ◽  
Vol 48 (4) ◽  
pp. 728-729
Author(s):  
M.J. Kim ◽  
L.C. Liu ◽  
S.H. Risbud ◽  
R.W. Carpenter
Keyword(s):  
Quantum Dots ◽  
Borosilicate Glass ◽  
Glass Matrix ◽  
Optical Switching ◽  
Response Times ◽  
Fast Response ◽  
Processing Technique ◽  
Internal Stresses ◽  
Electron Hole ◽  
Spatial Dimensions

When the size of a semiconductor is reduced by an appropriate materials processing technique to a dimension less than about twice the radius of an exciton in the bulk crystal, the band like structure of the semiconductor gives way to discrete molecular orbital electronic states. Clusters of semiconductors in a size regime lower than 2R {where R is the exciton Bohr radius; e.g. 3 nm for CdS and 7.3 nm for CdTe) are called Quantum Dots (QD) because they confine optically excited electron- hole pairs (excitons) in all three spatial dimensions. Structures based on QD are of great interest because of fast response times and non-linearity in optical switching applications.In this paper we report the first HREM analysis of the size and structure of CdTe and CdS QD formed by precipitation from a modified borosilicate glass matrix. The glass melts were quenched by pouring on brass plates, and then annealed to relieve internal stresses. QD precipitate particles were formed during subsequent "striking" heat treatments above the glass crystallization temperature, which was determined by differential thermal analysis.

Compact and efficient gas diffusion electrodes based on nanoporous alumina membranes for microfuel cells and gas sensors

The Analyst ◽  
2020 ◽  
Vol 145 (1) ◽  
pp. 122-131 ◽  
Author(s):  
Wanda V. Fernandez ◽  
Rocío T. Tosello ◽  
José L. Fernández
Keyword(s):  
Response Times ◽  
Hydrogen Oxidation ◽  
Fast Response ◽  
Gas Diffusion ◽  
Limiting Current ◽  
Gas Diffusion Electrodes ◽  
Nanoporous Alumina ◽  
Alumina Membranes ◽  
Current Densities ◽  
Microfuel Cells

Gas diffusion electrodes based on nanoporous alumina membranes electrocatalyze hydrogen oxidation at high diffusion-limiting current densities with fast response times.

scholarly journals FEM Simulation of Frequency-Selective Surface Based on Thermoelectric Bi-Sb Thin Films for THz Detection

Photonics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 119
Author(s):  
Anastasiia Tukmakova ◽  
Ivan Tkhorzhevskiy ◽  
Artyom Sedinin ◽  
Aleksei Asach ◽  
Anna Novotelnova ◽  
...  
Keyword(s):  
Thin Films ◽  
Response Times ◽  
Fem Simulation ◽  
Film Surface ◽  
Frequency Selective Surface ◽  
Fast Response ◽  
Radiation Absorption ◽  
Thz Radiation ◽  
Frequency Filter ◽  
Frequency Selective

Terahertz (THz) filters and detectors can find a wide application in such fields as: sensing, imaging, security systems, medicine, wireless connection, and detection of substances. Thermoelectric materials are promising basis for THz detectors’ development due to their sensitivity to the THz radiation, possibility to be heated under the THz radiation and produce voltage due to Seebeck effect. Thermoelectric thin films of Bi-Sb solid solutions are semimetals/semiconductors with the band gap comparable with THz energy and with high thermoelectric conversion efficiency at room temperature. Detecting film surface can be transformed into a periodic frequency selective surface (FSS) that can operate as a frequency filter and increases the absorption of THz radiation. We report for the first time about the simulation of THz detector based on thermoelectric Bi-Sb thin-filmed frequency-selective surface. We show that such structure can be both detector and frequency filter. Moreover, it was shown that FSS design increases not only a heating due to absorption but a temperature gradient in Bi-Sb film by two orders of magnitude in comparison with continuous films. Local temperature gradients can reach the values of the order of 100 K·mm−1. That opens new perspectives for thin-filmed thermoelectric detectors’ efficiency increase. Temperature difference formed due to THz radiation absorption can reach values on the order of 1 degree. Frequency-transient calculations show the power dependence of film temperature on time with characteristic saturation at times around several ms. That points to the perspective of reaching fast response times on such structures.

Novel optical oxygen sensing by phosphorescence quenching of palladium porphyrin self-assembled film on alumina plate

2000 ◽  
Vol 04 (02) ◽  
pp. 179-184 ◽  
Author(s):  
YUTAKA AMAO ◽  
KEISUKE ASAI ◽  
ICHIRO OKURA
Keyword(s):  
Oxygen Pressure ◽  
Oxygen Sensor ◽  
Response Times ◽  
Oxygen Sensing ◽  
Fast Response ◽  
Phosphorescence Quenching ◽  
Highly Sensitive ◽  
Optical Oxygen Sensor ◽  
Self Assembled ◽  
Quenching By Oxygen

An optical oxygen sensor based on the phosphorescence quenching of palladium tetrakis(4-carboxyphenyl)porphyrin (PdTCPP) self-assembled film (SAM) on alumina plate was developed. The phosphorescence intensity of PdTCPP film decreased with increasing oxygen pressure, indicating that the film can be used as an optical oxygen-sensing device based on phosphorescence quenching by oxygen. The ratio I0/I100 as a sensitivity measure of the sensing film is estimated to be 17.7, showing that the film is a highly sensitive device for oxygen pressure. The film obeyed Stern–Volmer plots with a multisite model and possessed good operational stability and a fast response. Response times are 36 s for deoxygenated to oxygenated conditions and 148 s for the reverse conditions.

Blast furnace model for gas flow control

1999 ◽  
Vol 96 (6) ◽  
pp. 715-720
Author(s):  
G. Danloy ◽  
J. Mignon ◽  
L. Bonte
Keyword(s):  
Blast Furnace ◽  
Flow Control ◽  
Gas Flow

A thermally activated paraffin-based actuator for gas-flow control in a satellite electrical propulsion system

2003 ◽  
Vol 105 (3) ◽  
pp. 237-246 ◽  
Author(s):  
Lena Klintberg ◽  
Mikael Karlsson ◽  
Lars Stenmark ◽  
Greger Thornell
Keyword(s):  
Flow Control ◽  
Gas Flow ◽  
Propulsion System ◽  
Thermally Activated ◽  
Electrical Propulsion

Sound suppressing gas flow control device

1980 ◽  
Vol 67 (4) ◽  
pp. 1413-1413
Author(s):  
George J. Kay ◽  
Alan Keskimen
Keyword(s):  
Flow Control ◽  
Gas Flow ◽  
Control Device ◽  
Flow Control Device

Gas Flow Control Employing Temperature and Pressure Compensation

1971 ◽  
Vol 93 (3) ◽  
pp. 200-205
Author(s):  
Seth R. Goldstein ◽  
Andrew C. Harvey
Keyword(s):  
Flow Control ◽  
Gas Flow ◽  
Absolute Temperature ◽  
Control Technique ◽  
Order Error ◽  
Upstream Pressure ◽  
Nonlinear Temperature ◽  
High Pressure Oxygen ◽  
Trapped Gas ◽  
Pressure Compensation

Two passive gas flow controllers are presented which provide compensation for variations in ambient temperature and supply pressure. One technique, which provides first-order error compensation, utilizes a choked orifice having its area linearily varied in proportion to a diaphragm deflection. Compensation is achieved by applying upstream pressure to one side of the diaphragm, and by applying a trapped gas pressure proportional to absolute temperature on the other side of the diaphragm. General design relationships are presented, and a prototype unit constructed to control a minute flow rate of high-pressure oxygen is described. A second flow control technique is presented which provides the required nonlinear temperature compensation for flow supplied through a constant-area choked orifice. This is achieved by utilizing a compliant volume of trapped gas to generate a pressure proportional to the square root of absolute temperature. This pressure is used to control the pressure upstream of the choked orifice, thus providing constant flow.

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