Modeling and Validation of Sensor and Actuator Dynamics for, And Real-Time Feedback Control of Thermal Chlorine Etching of Gallium Arsenide

1999 ◽  
Vol 569 ◽  
Author(s):  
I. G. Rosen ◽  
T. Parent ◽  
R. Mancera ◽  
P. Chen ◽  
A. Madhukar
Keyword(s):  
Gallium Arsenide ◽  
Real Time ◽  
Optical Measurements ◽  
Etch Depth ◽  
Linear Quadratic ◽  
Feedback Controllers ◽  
Actuator Dynamics ◽  
Primary Motivation ◽  
Design And Testing

ABSTRACTA dynamic model for the simulation of thermal chlorine etching of gallium arsenide is developed. The primary motivation for the development of the model is the design and testing of real time feedback controllers which rely upon in-situ optical measurements of etch depth obtained via spectroscopic ellipsometry. Unmeasurable parameters which appear in the model are identified, and the model is validated using experimental data. A linear-quadratic controller based on our model is designed and tested.

In Situ Control of Wet Etching Using Spectroscopic Ellipsometry

1998 ◽  
Vol 535 ◽  
Author(s):  
Sang-Jun Cho ◽  
P. G. Snyder
Keyword(s):  
Citric Acid ◽  
Real Time ◽  
Spectroscopic Ellipsometry ◽  
Wet Etching ◽  
Etch Depth ◽  
Algaas Layer ◽  
In Situ Control ◽  
Etch Rates

AbstractEtching of a GaAs/Al0.3Ga0.7As/GaAs heterostructure in a nonselective etch solution of 25:1:75 (citric acid: H2O2:H2O) was studied in-situ using real time spectroscopic ellipsometry (RTSE). Etch rates for GaAs and AIGaAs of 15.3 nm/min and 17.6 nm/min, respectively, were determined by numerically fitting RTSE data. RTSE was successfully used to stop the etch after removal of the thin GaAs cap, while removing very little of the underlying AlGaAs layer. In addition, etch depth into the AIGaAs layer was accurately controlled, using RTSE to stop the etch with 100 nm remaining. Finally, RTSE data for wet etching of a patterned sample (75% coverage with photoresist) showed similar behavior to that for the unpattemed sample.

scholarly journals Dosimetry with gafchromic films based on a new micro-opto-electro-mechanical system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
C. Guardiola ◽  
A. Márquez ◽  
M. C. Jiménez-Ramos ◽  
J. García López ◽  
A. Baratto-Roldán ◽  
...  
Keyword(s):  
Mechanical System ◽  
Real Time ◽  
Optical Measurements ◽  
Radiochromic Film ◽  
Light Emitting ◽  
Radiochromic Films ◽  
New Device ◽  
Active Sensor ◽  
Gafchromic Films

AbstractThis work presents the first tests performed with radiochromic films and a new Micro‒Opto‒Electro-Mechanical system (MOEMS) for in situ dosimetry evaluation in radiotherapy in real time. We present a new device and methodology that overcomes the traditional limitation of time-delay in radiochromic film analysis by turning a passive detector into an active sensor. The proposed system consists mainly of an optical sensor based on light emitting diodes and photodetectors controlled by both customized electronic circuit and graphical user interface, which enables optical measurements directly. We show the first trials performed in a low‒energy proton cyclotron with this MOEMS by using gafchromic EBT3 films. Results show the feasibility of using this system for in situ dose evaluations. Further adaptation is ongoing to develop a full real‒time active detector by integrating MOEM multi‒arrays and films in flexible printed circuits. Hence, we point to improve the clinical application of radiochromic films with the aim to optimize radiotherapy treatment verifications.

Probing the Dynamic Self-Assembly Behaviour of Photoswitchable Wormlike Micelles in Real Time

2018 ◽  
Author(s):  
Elaine A. Kelly ◽  
Judith E. Houston ◽  
Rachel Evans
Keyword(s):  
Real Time ◽  
Absorption Spectroscopy ◽  
Self Assembly ◽  
Uv Light ◽  
Wormlike Micelles ◽  
Tetraethylene Glycol ◽  
Light Illumination ◽  
First Time ◽  
Dependent Processes

Understanding the dynamic self-assembly behaviour of azobenzene photosurfactants (AzoPS) is crucial to advance their use in controlled release applications such as<i></i>drug delivery and micellar catalysis. Currently, their behaviour in the equilibrium <i>cis-</i>and <i>trans</i>-photostationary states is more widely understood than during the photoisomerisation process itself. Here, we investigate the time-dependent self-assembly of the different photoisomers of a model neutral AzoPS, <a>tetraethylene glycol mono(4′,4-octyloxy,octyl-azobenzene) </a>(C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>) using small-angle neutron scattering (SANS). We show that the incorporation of <i>in-situ</i>UV-Vis absorption spectroscopy with SANS allows the scattering profile, and hence micelle shape, to be correlated with the extent of photoisomerisation in real-time. It was observed that C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>could switch between wormlike micelles (<i>trans</i>native state) and fractal aggregates (under UV light), with changes in the self-assembled structure arising concurrently with changes in the absorption spectrum. Wormlike micelles could be recovered within 60 seconds of blue light illumination. To the best of our knowledge, this is the first time the degree of AzoPS photoisomerisation has been tracked <i>in</i><i>-situ</i>through combined UV-Vis absorption spectroscopy-SANS measurements. This technique could be widely used to gain mechanistic and kinetic insights into light-dependent processes that are reliant on self-assembly.

Flat Flexible Thin Milli-electrode Array for Real-time in situ Water Quality Monitoring in Distribution Systems

2017 ◽  
Vol 2017 (4) ◽  
pp. 5598-5617
Author(s):  
Zhiheng Xu ◽  
Wangchi Zhou ◽  
Qiuchen Dong ◽  
Yan Li ◽  
Dingyi Cai ◽  
...  
Keyword(s):  
Water Quality ◽  
Real Time ◽  
Distribution Systems ◽  
Electrode Array ◽  
Water Quality Monitoring ◽  
Quality Monitoring

scholarly journals Real-Time Energy Management of Parallel Hybrid Electric Vehicles Using Linear Quadratic Regulation

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5538
Author(s):  
Bảo-Huy Nguyễn ◽  
João Pedro F. Trovão ◽  
Ronan German ◽  
Alain Bouscayrol
Keyword(s):  
Real Time ◽  
Energy Management ◽  
Electric Vehicles ◽  
Hybrid Electric Vehicles ◽  
Engine Fuel ◽  
Linear Quadratic ◽  
Loop Control ◽  
Parallel Hybrid ◽  
Linear Quadratic Regulation ◽  
Hybrid Electric

Optimization-based methods are of interest for developing energy management strategies due to their high performance for hybrid electric vehicles. However, these methods are often complicated and may require strong computational efforts, which can prevent them from real-world applications. This paper proposes a novel real-time optimization-based torque distribution strategy for a parallel hybrid truck. The strategy aims to minimize the engine fuel consumption while ensuring battery charge-sustaining by using linear quadratic regulation in a closed-loop control scheme. Furthermore, by reformulating the problem, the obtained strategy does not require the information of the engine efficiency map like the previous works in literature. The obtained strategy is simple, straightforward, and therefore easy to be implemented in real-time platforms. The proposed method is evaluated via simulation by comparison to dynamic programming as a benchmark. Furthermore, the real-time ability of the proposed strategy is experimentally validated by using power hardware-in-the-loop simulation.

scholarly journals Underground Microseismic Event Monitoring and Localization within Sensor Networks

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2830
Author(s):  
Sili Wang ◽  
Mark P. Panning ◽  
Steven D. Vance ◽  
Wenzhan Song
Keyword(s):  
Sensor Networks ◽  
Real Time ◽  
Information Needs ◽  
Localization Algorithm ◽  
Distributed Sensors ◽  
Distributed Sensor ◽  
Microseismic Events ◽  
The Stability ◽  
Stability And Accuracy

Locating underground microseismic events is important for monitoring subsurface activity and understanding the planetary subsurface evolution. Due to bandwidth limitations, especially in applications involving planetarily-distributed sensor networks, networks should be designed to perform the localization algorithm in-situ, so that only the source location information needs to be sent out, not the raw data. In this paper, we propose a decentralized Gaussian beam time-reverse imaging (GB-TRI) algorithm that can be incorporated to the distributed sensors to detect and locate underground microseismic events with reduced usage of computational resources and communication bandwidth of the network. After the in-situ distributed computation, the final real-time location result is generated and delivered. We used a real-time simulation platform to test the performance of the system. We also evaluated the stability and accuracy of our proposed GB-TRI localization algorithm using extensive experiments and tests.

Sign in / Sign up

Export Citation Format

Share Document