1,350 research outputs found
Analysis of the impact of data compression on condition monitoring algorithms for ball screws
The overall equipment effectiveness (OEE) is a management ratio to evaluate the added value of machine tools. Unplanned machine downtime reduces the operational availability and therefore, the OEE. Increased machine costs are the consequence. An important cause of unplanned machine downtimes is the total failure of ball screws of the feed axes due to wear. Therefore, monitoring of the condition of ball screws is important. Common concepts rely on high-frequency acceleration sensors from external control systems to detect a change of the condition. For trend and detailed damage analysis, large amounts of data are generated and stored over a long time period (>5 years), resulting in corresponding data storage costs. Additional axes or machine tools increase the data volume further, adding to the total storage costs. To minimize these costs, data compression or source coding has to be applied. To achieve maximum compression ratios, lossy coding algorithms have to be used, which introduce distortion in a signal. In this work, the influence of lossy coding algorithms on a condition monitoring algorithm (CMA) using acceleration signals is investigated. The CMA is based on principal component analysis and uses 17 features such as standard deviation to predict the preload condition of a ball screw. It is shown that bit rate reduction through lossy compression algorithms is possible without affecting the condition monitoring - as long as the compression algorithm is known. In contrast, an unknown compression algorithm reduces the classification accuracy of condition monitoring by about 20 % when coding with a quantizer resolution of 4 bit/sample
MaskLab: Instance Segmentation by Refining Object Detection with Semantic and Direction Features
In this work, we tackle the problem of instance segmentation, the task of
simultaneously solving object detection and semantic segmentation. Towards this
goal, we present a model, called MaskLab, which produces three outputs: box
detection, semantic segmentation, and direction prediction. Building on top of
the Faster-RCNN object detector, the predicted boxes provide accurate
localization of object instances. Within each region of interest, MaskLab
performs foreground/background segmentation by combining semantic and direction
prediction. Semantic segmentation assists the model in distinguishing between
objects of different semantic classes including background, while the direction
prediction, estimating each pixel's direction towards its corresponding center,
allows separating instances of the same semantic class. Moreover, we explore
the effect of incorporating recent successful methods from both segmentation
and detection (i.e. atrous convolution and hypercolumn). Our proposed model is
evaluated on the COCO instance segmentation benchmark and shows comparable
performance with other state-of-art models.Comment: 10 pages including referenc
Generative Compression
Traditional image and video compression algorithms rely on hand-crafted
encoder/decoder pairs (codecs) that lack adaptability and are agnostic to the
data being compressed. Here we describe the concept of generative compression,
the compression of data using generative models, and suggest that it is a
direction worth pursuing to produce more accurate and visually pleasing
reconstructions at much deeper compression levels for both image and video
data. We also demonstrate that generative compression is orders-of-magnitude
more resilient to bit error rates (e.g. from noisy wireless channels) than
traditional variable-length coding schemes
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