Electron holography of p-n junctions

1996 ◽  
Vol 54 ◽  
pp. 974-975
Author(s):  
B.G. Frost ◽  
D.C. Joy ◽  
L.F. Allard ◽  
E. Voelkl
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Field Emission ◽  
Ccd Camera ◽  
Image Plane ◽  
Reference Wave ◽  
Field Of View ◽  
Control Mode ◽  
Objective Lens ◽  
Electron Holography

A wide holographic field of view (up to 15 μm in the Hitachi-HF2000) is achieved in a TEM by switching off the objective lens and imaging the sample by the first intermediate lens. Fig.1 shows the corresponding ray diagram for low magnification image plane off-axis holography. A coherent electron beam modulated by the sample in its amplitude and its phase is superimposed on a plane reference wave by a negatively biased Möllenstedt-type biprism.Our holograms are acquired utilizing a Hitachi HF-2000 field emission electron microscope at 200 kV. Essential for holography are a field emission gun and an electron biprism. At low magnification, the excitation of each lens must be appropriately adjusted by the free lens control mode of the microscope. The holograms are acquired by a 1024 by 1024 slow-scan CCD-camera and processed by the “Holoworks” software. The hologram fringes indicate positively and negatively charged areas in a sample by the direction of the fringe bending (Fig.2).

Automation Surprise

2017 ◽  
Vol 7 (1) ◽  
pp. 28-41 ◽  
Author(s):  
Robert J. de Boer ◽  
Karel Hurts
Keyword(s):  
Flight Control ◽  
Representative Sample ◽  
Aviation Safety ◽  
Control Mode ◽  
Cognitive Errors ◽  
Laboratory Studies ◽  
Airline Pilots ◽  
Flight Operations ◽  
Widespread Phenomenon ◽  
Few Data

Abstract. Automation surprise (AS) has often been associated with aviation safety incidents. Although numerous laboratory studies have been conducted, few data are available from routine flight operations. A survey among a representative sample of 200 Dutch airline pilots was used to determine the prevalence of AS and the severity of its consequences, and to test some of the factors leading to AS. Results show that AS is a relatively widespread phenomenon that occurs three times per year per pilot on average but rarely has serious consequences. In less than 10% of the AS cases that were reviewed, an undesired aircraft state was induced. Reportable occurrences are estimated to occur only once every 1–3 years per pilot. Factors leading to a higher prevalence of AS include less flying experience, increasing complexity of the flight control mode, and flight duty periods of over 8 hr. It is concluded that AS is a manifestation of system and interface complexity rather than cognitive errors.

Intensive care of a complicated form of asthmatic status (clinical case)

2019 ◽  
Vol 2 (31) ◽  
pp. 46-51
Author(s):  
D. A. Temerov ◽  
L. V. Vorobyova ◽  
S. V. Vyzhevsky ◽  
S. B. Savchenkov ◽  
Yu. V. Marchenkov
Keyword(s):  
Clinical Case ◽  
Mixture Distribution ◽  
Severe Pneumonia ◽  
Control Mode ◽  
Respiratory Support ◽  
Oxygen Mixture ◽  
Bronchial Obstruction ◽  
Optimal Regime ◽  
Pulmonary Barotrauma ◽  
Airway Patency

The article presents a clinical case of successful treatment of a patient with prolonged asthmatic status. The pathogenesis of purulent-septic and other life-threatening complications developing as a result of the above critical condition is described. The positive effect of a differentiated approach in conducting respiratory support depending on the stage of the disease is justified: at the beginning, when airway obstruction is in the foreground, and in the future, when restrictive respiratory disorders develop. When conducting respiratory support, the most reasonable methods for ensuring airway patency were selected. The necessity of neurovegetative blockade and myoplegia for the prevention of pulmonary barotrauma during respiratory support by aggressive ventilation modes and with the goal of antihypoxic protection of the brain is emphasized. During the treatment of the patient, it was confirmed that the optimal regime for obstruction of the bronchi is forced volume-cyclic ventilation of the lungs to provide the necessary minute volume of breathing, and in severe pneumonia, in the case of relief of bronchial obstruction, respiratory support is carried out in pressure control mode for better air-oxygen mixture distribution in the airways. The need for early tracheostomy and daily therapeutic fibrobronchoscopy to ensure airway patency and treat pneumonia has been confirmed.

scholarly journals Optimization of the Fuel Cell Renewable Hybrid Power System Using the Control Mode of the Required Load Power on the DC Bus

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1889 ◽  
Author(s):  
Nicu Bizon ◽  
Valentin Alexandru Stan ◽  
Angel Ciprian Cormos
Keyword(s):  
Energy Source ◽  
Fuel Cell ◽  
Power System ◽  
Control Mode ◽  
Variable Load ◽  
Hybrid Power System ◽  
Hybrid Power ◽  
Load Power ◽  
Load Demand ◽  
Dc Bus

In this paper, a systematic analysis of seven control topologies is performed, based on three possible control variables of the power generated by the Fuel Cell (FC) system: the reference input of the controller for the FC boost converter, and the two reference inputs used by the air regulator and the fuel regulator. The FC system will generate power based on the Required-Power-Following (RPF) control mode in order to ensure the load demand, operating as the main energy source in an FC hybrid power system. The FC system will operate as a backup energy source in an FC renewable Hybrid Power System (by ensuring the lack of power on the DC bus, which is given by the load power minus the renewable power). Thus, power requested from the batteries’ stack will be almost zero during operation of the FC hybrid power system based on RPF-control mode. If the FC hybrid power system operates with a variable load demand, then the lack or excess of power on the DC bus will be dynamically ensured by the hybrid battery/ultracapacitor energy storage system for a safe transition of the FC system under the RPF-control mode. The RPF-control mode will ensure a fair comparison of the seven control topologies based on the same optimization function to improve the fuel savings. The main objective of this paper is to compare the fuel economy obtained by using each strategy under different load cycles in order to identify which is the best strategy operating across entire loading or the best switching strategy using two strategies: one strategy for high load and the other on the rest of the load range. Based on the preliminary results, the fuel consumption using these best strategies can be reduced by more than 15%, compared to commercial strategies.

scholarly journals A Cost-Effective Decentralized Control for AC-Stacked Photovoltaic Inverters

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2262 ◽  
Author(s):  
Hua Han ◽  
Chao Luo ◽  
Xiaochao Hou ◽  
Mei Su ◽  
Wenbin Yuan ◽  
...  
Keyword(s):  
Decentralized Control ◽  
Cost Effective ◽  
Current Control ◽  
Control Mode ◽  
Communication Link ◽  
Grid Voltage ◽  
Point Tracking ◽  
Pv Inverter ◽  
Communication Links ◽  
Voltage Phase

For an AC-stacked photovoltaic (PV) inverter system with N cascaded inverters, existing control methods require at least N communication links to acquire the grid synchronization signal. In this paper, a novel decentralized control is proposed. For N inverters, only one inverter nearest the point of common coupling (PCC) needs a communication link to acquire the grid voltage phase and all other N − 1 inverters use only local measured information to achieved fully decentralized local control. Specifically, one inverter with a communication link utilizes the grid voltage phase and adopts current control mode to achieve a required power factor (PF). All other inverters need only local information without communication links and adopt voltage control mode to achieve maximum power point tracking (MPPT) and self-synchronization with grid voltage. Compared with existing methods, the communication link and complexity is greatly reduced, thus improved reliability and reduced communication costs are achieved. The effectiveness of the proposed control is verified by simulation tests.

Analysing integration issues of the microgrid system with utility grid network

2021 ◽  
Vol 22 (1) ◽  
pp. 113-127
Author(s):  
Mulualem Tesfaye ◽  
Baseem Khan ◽  
Om Prakash Mahela ◽  
Hassan Haes Alhelou ◽  
Neeraj Gupta ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Distribution System ◽  
Reactive Power ◽  
Renewable Energy Sources ◽  
Operating Conditions ◽  
Control Mode ◽  
Voltage Source ◽  
Modulation Scheme ◽  
Main Challenge ◽  
Utility Grid

Abstract Generation of renewable energy sources and their interfacing to the main system has turn out to be most fascinating challenge. Renewable energy generation requires stable and reliable incorporation of energy to the low or medium voltage networks. This paper presents the microgrid modeling as an alternative and feasible power supply for Institute of Technology, Hawassa University, Ethiopia. This microgrid consists of a 60 kW photo voltaic (PV) and a 20 kW wind turbine (WT) system; that is linked to the electrical distribution system of the campus by a 3-phase pulse width modulation scheme based voltage source inverters (VSI) and supplying power to the university buildings. The main challenge in this work is related to the interconnection of microgrid with utility grid, using 3-phase VSI controller. The PV and WT of the microgrid are controlled in active and reactive power (PQ) control mode during grid connected operation and in voltage/frequency (V/F) control mode, when the microgrid is switched to the stand-alone operation. To demonstrate the feasibility of proposed microgrid model, MATLAB/Simulink software has been employed. The performance of fully functioning microgrid is analyzed and simulated for a number of operating conditions. Simulation results supported the usefulness of developed microgrid in both mode of operation.

Real power regulation design for multi-terminal VSC-HVDC systems

2013 ◽  
Vol 3 (2) ◽  
Author(s):  
Guo-Jie Li ◽  
Si-Ye Ruan ◽  
Tek Lie
Keyword(s):  
Control Strategy ◽  
Control Mode ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Real Power ◽  
The Real ◽  
Hvdc System ◽  
High Voltage Direct Current ◽  
Power Regulation ◽  
Regulation Functions

AbstractA multi-terminal voltage-source-converter (VSC) based high voltage direct current (HVDC) system is concerned for its flexibility and reliability. In this study, a control strategy for multiple VSCs is proposed to auto-share the real power variation without changing control mode, which is based on “dc voltage droop” power regulation functions. With the proposed power regulation design, the multiple VSCs automatically share the real power change and the VSC-HVDC system is stable even under loss of any one converter while there is no overloading for any individual converter. Simulation results show that it is effective to balance real power for power disturbance and thus improves operation reliability for the multi-terminal VSC-HVDC system by the proposed control strategy.

Key Technologies of the Embedded Deformation Measuring Control System Based on SOPC

2014 ◽  
Vol 644-650 ◽  
pp. 773-776
Author(s):  
Qiu Hong Song
Keyword(s):  
Deformation Measurement ◽  
Control Mode ◽  
Precision Engineering ◽  
Automatic Data ◽  
Industrial Buildings ◽  
The Status ◽  
Rock Mass Deformation ◽  
Crust Deformation ◽  
Measuring Control ◽  
Automatic Data Acquisition

Deformation measurement is an important content of engineering surveying and the main objects of the deformation measurement are civilians, industrial buildings, precision engineering, large dam, bridge and the earth's crust deformation of rock mass. Deformation measurement aims to obtain the deformation data in the process of displacement deformation, and to get the deformation of the status, trend and possible results through the analysis of these data. The existing automatable solution for measuring the deformation all adopt the 3-dimension displacement test, which based on high precision total station, unattended, automatic data acquisition and transmission control mode.

Study on Reactive Power Compensation Control of STATCOM Based on MMC

2014 ◽  
Vol 530-531 ◽  
pp. 1022-1025
Author(s):  
Yan Xie ◽  
Ya Ne Liao ◽  
Hong Xie
Keyword(s):  
Reactive Power ◽  
Power Level ◽  
Response Speed ◽  
Reactive Power Compensation ◽  
Current Control ◽  
Control Mode ◽  
Compensation Control ◽  
Control Response ◽  
In Series ◽  
Level Converter

This paper introduced a new modular multi-level converter (MMC), which could enhance the voltage and power level by sub-converter modules in series and was easy to extend to any level of output. Its structure and working mechanism were described. By analyzing the performance of STATCOM based on MMC working conditions in the reactive power compensation, this paper studied compensation control theory in reactive changing conditions. To obtain compensation control response speed faster and better compensation effect, a compensation control strategy was proposed based on direct current control mode. The simulation results show the strategy has a better tracking precision and response speed for the reactive power compensation.

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