Epitaxy of Arsenic-Pressure-Controlled MBE-Grown GaAs Layers

1985 ◽  
Vol 56 ◽  
Author(s):  
Y.H. Wang ◽  
W.C. Liu ◽  
C.Y. Chang ◽  
M.S. Jean ◽  
S.A. Liao
Keyword(s):  
Control Method ◽  
Defect Density ◽  
Growth Parameters ◽  
Pressure Control ◽  
Effusion Cell ◽  
Substrate Type ◽  
Temperature Growth ◽  
Surface Morphologies ◽  
Oval Defect ◽  
Pressure Controlled

AbstractSurface morphologies of the molecular beam epitaxy (MBE)-grown GaAs layers using the background-arsenic-pressure-control method were investigated. The growth parameters, such as substrate temperature, growth rate, epilayer thickness, As/Ga ratio, doping concentration, substrate type, etc., are related to the observed oval defect density. Protrusions and Ga-droplets caused oval defects during growth. The origin of the oval defects in our system is found to be the gallium oxide, not Ga "spitting" from the effusion cell.

Influence of growth parameters and conditions on the oval defect density in GaAs layers grown by MBE

1989 ◽  
Vol 96 (3) ◽  
pp. 533-540 ◽  
Author(s):  
P.S. Kop'ev ◽  
S.V. Ivanov ◽  
A.Yu. Yegorov ◽  
D.Yu. Uglov
Keyword(s):  
Defect Density ◽  
Growth Parameters ◽  
Oval Defect

Stoichiometry Control of Compound Semiconductors

1992 ◽  
Vol 242 ◽  
Author(s):  
Jun-Ichi Nishizawa ◽  
Ken Suto ◽  
Yutaka Oyama
Keyword(s):  
Vapor Pressure ◽  
Emission Spectra ◽  
Pressure Control ◽  
Optical Microscope ◽  
Double Crystal ◽  
Temperature Growth ◽  
Bulk Crystal Growth ◽  
Group I ◽  
P Type ◽  
Stoichiometry Control

ABSTRACTVapor pressure control technology is successfully applied to the bulk crystal growth, epitaxial growth and diffusion process of ZnSe crystals. Surface morphology and the crystal quality are investigated by the optical microscope and the X-ray double crystal diffractometry as the function of the growth temperature and the applying Zn vapor pressure. The cathode luminescence is also measured to evaluate the optical properties and the effect of low temperature growth and the application of Zn vapor pressure are demonstrated, p-type ZnSe crystals are grown from the Se solution with group Ia element as a dopant under controlled Zn vapor pressure, p-n junction diodes are also prepared by the Ga diffusion from Zn solution under Se vapor pressure. Emission spectra from the p-n junction and its Zn and Se vapor pressure dependencies are also presented.

Crisis Ventilator: A 3D Printed Option for Pressure Controlled Ventilation

2020 ◽  
Author(s):  
Alex Brito ◽  
Evan Fontaine ◽  
S. James El Haddi ◽  
Albert Chi MD FACS
Keyword(s):  
Raw Materials ◽  
Tension Pneumothorax ◽  
Pressure Control ◽  
Control Ventilation ◽  
Pressure Control Ventilation ◽  
Controlled Ventilation ◽  
Pressure Controlled Ventilation ◽  
Clinical Scenarios ◽  
3D Printed ◽  
Pressure Controlled

Abstract During the Coronavirus-19, or COVID-19, pandemic there was an early shortage of available ventilators. Domestic production was limited by dependence on overseas sources of raw materials despite partnering with automotive manufacturers. Our group has developed a 3D printed alternative called the CRISIS ventilator. Its design is similar to existing resuscitator devices on the market and uses a modified Pressure-Control ventilation. Here we compare the performance of the device on a simulated ARDS lung and handling of different clinical scenarios included tension pneumothorax and bronchospasm.

Three-Dimensional Pressure Controlled Vortex Design of a Turbine Stage

2012 ◽  
Author(s):  
Qingfeng Deng ◽  
Qun Zheng ◽  
Guoqiang Yue ◽  
Hai Zhang ◽  
Mingcong Luo
Keyword(s):  
Pressure Gradient ◽  
Secondary Flow ◽  
Three Dimensional ◽  
Pressure Control ◽  
Turbine Stage ◽  
Stream Surface ◽  
Control Approach ◽  
Flow Losses ◽  
Pressure Controlled ◽  
Surface Thickness

A three-dimensional (3D) Pressure Controlled Vortex Design (PCVD) method for turbine stage design is proposed and discussed in this paper. The concept is developed from conventional Controlled Vortex Design (CVD) via pressure control approach and CVD technology. By specifying the static pressure and axial velocity distributions, the spanwise pressure gradient incorporated with pressure gradient in streamwise and azimuthal directions is moderated. Not only can profile loss profit from pressure control approach, but also secondary flow can be managed. The reasons for CVD are derived from stream surface thickness and stream surface twist. Through modifying stream surface thickness and inducing large stream surface twist, the secondary flow migrations are controlled properly and orderly. The relations of pressure control approach and CVD technology complement one another and finally lead to a well-posed flow pattern in turbine stage. The first stage redesign of a well-designed low pressure turbine demonstrates this technique application. A significant reduction of secondary flow losses and a corresponding increase of stage efficiency have achieved.

scholarly journals Stable Switching Control Strategy of the Support Pressure and Velocity of Shield Machine Gripper Shoes

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Nannan Liu ◽  
Jishen Peng ◽  
Liye Song ◽  
Pinhe Wang ◽  
Kun Zhang
Keyword(s):  
Position Control ◽  
Control Method ◽  
Control Strategies ◽  
Pressure Control ◽  
Surrounding Rock ◽  
Support Pressure ◽  
Hydraulic Pressure ◽  
Compound Control ◽  
Hydraulic Servo ◽  
Shield Machine

An electro-hydraulic servo position and pressure compound control method was investigated considering the working principle of a hydraulic stepping motor of a shield machine gripper shoe and its practical working characteristics in the supporting process. The control targets were to improve the support efficiency and reduce the disturbance of gripper shoes on the surrounding rock. In this method, a fuzzy switching controller was used to switch between electro-hydraulic position control and electro-hydraulic pressure control. Numerical and prototype simulation experiments were conducted on the control method. The theoretical analysis and experimental results showed that the control method could effectively convert the gripper shoes from an unsupported state to a supported state in a short amount of time, as well as realize surge-free switching between position control and pressure control. Thus, disturbance of the gripper shoes on the surrounding rock could be reduced. The results of this study provide a theoretical basis for research on control strategies of hydraulic stepping propulsion of shield machines.

Research on the Key Technology of NC Abrasive Belt Grinding for the Leading and Trailing Edges of Aeroengine Blades

2012 ◽  
Vol 565 ◽  
pp. 76-81 ◽  
Author(s):  
Yun Huang ◽  
Xiao Xiao Ye ◽  
Ming De Zhang ◽  
Hong Wen Fang
Keyword(s):  
Control Method ◽  
Dimensional Accuracy ◽  
Pressure Control ◽  
Grinding Process ◽  
Belt Grinding ◽  
Key Technology ◽  
Abrasive Belt ◽  
Model Research ◽  
Trailing Edges ◽  
Blade Machining

This document provides an analysis of the structure characteristics and grinding process requirements of leading and trailing edges, and proposes a grinding process of leading and trailing edges, established a uneven grinding margin model, research the quantitative grinding pressure control method of uneven margin, as well as the error compensation technology of blade machining deformation, and experiments were carried out on the basis of theories above. The experimental results demonstrate that: after grinding, the edge roundness improved greatly, dimensional accuracy of edge radius can reach ±0.07mm.Compared with the traditional manual polishing method, the grinding quality improved significantly.

Control and Optimization of Negative Pressure in Scrap Copper Smelting

2011 ◽  
Vol 103 ◽  
pp. 399-403
Author(s):  
Ying Dao Li ◽  
Wei Hong Zhong ◽  
Hong Wei Guan ◽  
Xiu Shui Ma
Keyword(s):  
Pid Control ◽  
Negative Pressure ◽  
Control Method ◽  
Control Variable ◽  
Pressure Control ◽  
Copper Smelting ◽  
Smelting Process ◽  
Adjustment Process ◽  
Optimization Control

Negative pressure is the main control variable in scrap copper smelting process, the control of negative pressure is not only closely related with producing safely, but also produces a direct impact on the quality of the anode plate, it is also a key breakthrough in energy saving. This paper first analyses the characteristics of negative pressure control in scrap copper smelting process, aims to larger overshoot and longer regulation under conventional PID control method, and then utilizes fuzzy control to correct the PID parameters online, to achieve the optimization control of negative pressure. Simulation result shows that the adjustment process of optimized control of negative pressure is steady and rapid, usually no or slightly overshoot, and the settling time is also reduced significantly.

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