4,271 research outputs found
Improved intensifying screen reduces X-ray exposure
X-ray intensifying screen may make possible radiographic procedures where detection speed and X-ray tube power have been the limiting factors. Device will reduce total population exposure to harmful radiation in the United States
Evaluation of a fault tolerant system for an integrated avionics sensor configuration with TSRV flight data
The performance analysis results of a fault inferring nonlinear detection system (FINDS) using sensor flight data for the NASA ATOPS B-737 aircraft in a Microwave Landing System (MLS) environment is presented. First, a statistical analysis of the flight recorded sensor data was made in order to determine the characteristics of sensor inaccuracies. Next, modifications were made to the detection and decision functions in the FINDS algorithm in order to improve false alarm and failure detection performance under real modelling errors present in the flight data. Finally, the failure detection and false alarm performance of the FINDS algorithm were analyzed by injecting bias failures into fourteen sensor outputs over six repetitive runs of the five minute flight data. In general, the detection speed, failure level estimation, and false alarm performance showed a marked improvement over the previously reported simulation runs. In agreement with earlier results, detection speed was faster for filter measurement sensors soon as MLS than for filter input sensors such as flight control accelerometers
An On-line Diagnostic Method for Open-circuit Switch Faults in NPC Multilevel Converters
On-line condition monitoring is of paramount importance for multilevel converters used in safety-critical applications. A novel on-line diagnostic method for detecting open-circuit switch faults in neutral-point-clamped (NPC) multilevel converters is introduced in this paper. The principle of this method is based on monitoring the abnormal variation of the dc-bus neutral-point current in combination with the existing information on instantaneous switching states and phase currents. Advantages of this method include simpler implementation and faster detection speed compared to other existing diagnostic methods in the literature. In this method, only one additional current sensor is required for measuring the dc-bus neutral-point current, therefore the implementation cost is low. Simulation and experimental results based on a lab-scale 50 kVA adjustable speed drive (ASD) with a three-level NPC inverter validate the efficacy of this novel diagnostic method
Sensitivity limitations in optical speed meter topology of gravitational-wave antennae
The possible design of QND gravitational-wave detector based on speed meter
principle is considered with respect to optical losses. The detailed analysis
of speed meter interferometer is performed and the ultimate sensitivity that
can be achieved is calculated. It is shown that unlike the position meter
signal-recycling can hardly be implemented in speed meter topology to replace
the arm cavities as it is done in signal-recycled detectors, such as GEO 600.
It is also shown that speed meter can beat the Standard Quantum Limit (SQL) by
the factor of in relatively wide frequency band, and by the factor of
in narrow band. For wide band detection speed meter requires quite
reasonable amount of circulating power MW. The advantage of the
considered scheme is that it can be implemented with minimal changes in the
current optical layout of LIGO interferometer.Comment: 20 pages, 12 figure
A surface defect detection method of steel plate based on YOLOV3
At present, the steel plate surface defect detection technology based on machine vision and convolutional neural network (CNN) has achieved good results. However, these models are mostly two-stage methods, extracting features first and then classifying them, which is slow and inaccurate. Therefore, this paper proposes a single-stage surface defect detection method of steel plate based on yolov3, which can classify defects, determine the location of defects, and greatly improve the detection speed. It is of great significance to realize the automation of cold rolling production line. The experiment shows that the detection speed of this model reaches 62 fps and the accuracy reaches 73 %, which has a good prospect in industry
A surface defect detection method of steel plate based on YOLOV3
At present, the steel plate surface defect detection technology based on machine vision and convolutional neural network (CNN) has achieved good results. However, these models are mostly two-stage methods, extracting features first and then classifying them, which is slow and inaccurate. Therefore, this paper proposes a single-stage surface defect detection method of steel plate based on yolov3, which can classify defects, determine the location of defects, and greatly improve the detection speed. It is of great significance to realize the automation of cold rolling production line. The experiment shows that the detection speed of this model reaches 62 fps and the accuracy reaches 73 %, which has a good prospect in industry
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