Tests of an Improved Rotating Stall Control System on a J-85 Turbojet Engine

1980 ◽  
Vol 102 (4) ◽  
pp. 903-911 ◽  
Author(s):  
G. R. Ludwig ◽  
J. P. Nenni
Keyword(s):  
Control System ◽  
Response Time ◽  
Detection System ◽  
Response Speed ◽  
Rotating Stall ◽  
The Past ◽  
Turbojet Engine ◽  
Design Speed ◽  
Stall Control ◽  
Selection Of

An improved version of a rotating stall control system has been tested successfully on a J-85-B turbojet engine. Past tests had pointed out the desirability of increasing the response speed of the control. In this study, the installation of the stall control on the J-85 was modified so as to decrease the response time of the control by a factor of ten over that attained in the past tests. The modified control was tested to see if the decreased response time improved the ability to clear rotating stall once it has started, and also to see if rotating stall could be anticipated and prevented by proper selection of the variables in the stall control detection system. The performance of the stall control was tested by closing the bleed doors on the engine until rotating stall occurred or until the control anticipated stall and held the bleed doors open. The tests showed that the control is capable of anticipating stall before it occurs and keeping the engine completely clear of stall at speeds up to 80 percent of design speed. No tests were performed above 80 percent of design speed because opening the bleed doors at such speeds might aggravate the stall rather than clear it.

A Rotating Stall Control System for Turbojet Engines

1979 ◽  
Vol 101 (3) ◽  
pp. 305-313 ◽  
Author(s):  
G. R. Ludwig ◽  
J. P. Nenni
Keyword(s):  
Control System ◽  
Rotating Stall ◽  
Prototype System ◽  
Variable Geometry ◽  
Hydraulic Actuator ◽  
Low Speed ◽  
Correction Signal ◽  
Geometry Feature ◽  
Stall Control ◽  
Stagger Angle

This paper describes the operating principle of a rotating stall control system and the results of testing a prototype control on a low-speed research compressor and on a J-85-5 turbojet engine. The control is an electrical feed-back control system which uses unsteady pressure signals produced by sensors within the compressor to detect the presence of stall and provide a correction signal when stall occurs. In the prototype system, the correction signal is used to drive a hydraulic actuator which provides a mechanical operation on some variable geometry feature of the compressor being controlled. On the low-speed research compressor the variable geometry was the stagger angle of the stator rows. On the J-85 engine, the control was installed to override the normal operating schedule of the compressor bleed doors and flaps on the inlet guide vanes. Both series of tests were successful in that the control rapidly eliminated rotating stall when it occurred and in some cases did not allow rotating stall to occur at all.

scholarly journals Striatal BOLD and midfrontal theta power express motivation for action

2020 ◽  
Author(s):  
Johannes Algermissen ◽  
Jennifer C. Swart ◽  
René Scheeringa ◽  
Roshan Cools ◽  
Hanneke E.M. den Ouden
Keyword(s):  
Response Time ◽  
Temporal Resolution ◽  
Response Speed ◽  
Action Selection ◽  
Learning Task ◽  
Dual Nature ◽  
Evidence Accumulation ◽  
Theta Power ◽  
Selection Of

AbstractAction selection is biased by the valence of anticipated outcomes. To assess mechanisms by which these motivational biases are expressed and controlled, we measured simultaneous EEG-fMRI during a motivational Go/NoGo learning task (N=36), leveraging the temporal resolution of EEG and subcortical access of fMRI. VmPFC BOLD encoded cue valence, importantly predicting trial-by-trial valence-driven response speed differences and EEG theta power around cue onset. In contrast, striatal BOLD encoded selection of active Go responses and correlated with theta power around response time. Within trials, theta power ramped in the fashion of an evidence accumulation signal for the value of making a ‘Go’ response, capturing the faster responding to reward cues. Our findings reveal a dual nature of midfrontal theta power, with early components reflecting the vmPFC contribution to motivational biases, and late components reflecting their striatal translation into behavior, in line with influential recent “value of work” theories of striatal processing.

scholarly journals Stall Inception and the Prospects for Active Control in Four High Speed Compressors

1997 ◽  
Author(s):  
I. J. Day ◽  
T. Breuer ◽  
J. Escuret ◽  
M. Cherrett ◽  
A. Wilson
Keyword(s):  
Control System ◽  
Active Control ◽  
High Speed ◽  
Rotating Stall ◽  
Collaborative Project ◽  
Stall Inception ◽  
Speed Range ◽  
Full Speed ◽  
Stall Warning ◽  
Stall Control

As part of a European collaborative project, four high speed compressors were tested to investigate the generic features of stall inception in aero-engine type compressors. Tests were run over the full speed range to identify the design and operating parameters which influence the stalling process. A study of data analysis techniques was also conducted in the hope of establishing early warning of stall. The work presented here is intended to relate the physical happenings in the compressor to the signals that would be received by an active stall control system. The measurements show a surprising range of stall related disturbances and suggest that spike-type stall inception is a feature of low speed operation while modal activity is clearest in the mid speed range. High frequency disturbances were detected at both ends of the speed range and non-rotating stall, a new phenomenon, was detected in three out of the four compressors. The variety of the stalling patterns, and the ineffectiveness of the stall warning procedures, suggests that the ultimate goal of a flightworthy active control system remains some way off.

scholarly journals SPHIRE-crYOLO: A fast and accurate fully automated particle picker for cryo-EM

2018 ◽  
Author(s):  
Thorsten Wagner ◽  
Felipe Merino ◽  
Markus Stabrin ◽  
Toshio Moriya ◽  
Claudia Antoni ◽  
...  
Keyword(s):  
Image Processing ◽  
Detection System ◽  
Learning Object ◽  
Electron Cryomicroscopy ◽  
High Recall ◽  
Essential Step ◽  
The Past ◽  
General Network ◽  
Manual Selection ◽  
Selection Of

AbstractSelecting particles from digital micrographs is an essential step in single particle electron cryomicroscopy (cryo-EM). Since manual selection of complete datasets typically comprising many thousands of particles is a tedious and time-consuming process, many automatic particle pickers have been developed in the past few decades. However, non-ideal datasets pose a challenge to particle picking. Here, we present a novel automated particle picking software called crYOLO, which is based on the deep learning object detection system “You Only Look Once” (YOLO). After training the network with 500 – 2,500 particles per dataset, it automatically recognizes particles with high recall and precision reaching a speed of up to five micrographs per second. Importantly, we demonstrate a powerful general network trained on more than 40 datasets to select previously unseen datasets, thus paving the way for completely automated “on-the-fly” cryo-EM data pre-processing during data acquisition. CrYOLO is available as a standalone program under http://sphire.mpg.de/ and will be part of the image processing workflow in SPHIRE.

Decoupled controller for mixed exhausts turbofan engine

2006 ◽  
Vol 110 (1114) ◽  
pp. 783-792
Author(s):  
T. R. Nada
Keyword(s):  
Control System ◽  
Fuzzy Controller ◽  
Response Speed ◽  
Similar Response ◽  
Turbofan Engines ◽  
Engine Control System ◽  
Surge Margin ◽  
Simple Logic ◽  
Temperature Margin ◽  
Selection Of

This paper points out the capabilities of fully decoupled fuzzy controller which introduces simple design approach to deal with the coupling effects in controlling two spools, mixed exhausts turbofan engines. The decoupling is performed through proper selection of input parameters to the controller. Digital nonlinear engine/control system simulation is used to construct the fuzzy rules depending on simple logic. The performance of this controller is compared with that of an optimal controller representing efficient classical and conventional techniques. The decoupled fuzzy control system produces favorable transient strategies that other conventional controllers can not attempt due to its inherent proportionality characteristics. It displays improvements in surge margin for both fan and compressor, and temperature margin with almost similar response time during acceleration. Also, the proposed controller has the capabilities to increase the response speed during deceleration independently from acceleration transient.

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