We propose a simple feature extraction algorithm for license plate location, which can reduce the occurrence of pseudo-licenses significantly. Our scheme arises from a novel L0-norm image smoothing, in which the multiple local textures in the complex backgrounds can be suppressed remarkably without changing the structures and edges of the license objects. Due to this “edgeaware” property, we then combine a feature filtering with an efficient binarized image, a simple multi-scale image analysis algorithm, to remove the potential false license plates. Finally, we extract license plates with a projection method. Experimental results show the proposed method provides a flexible and powerful way to the license plate location in complex backgrounds.

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In order to study the influence of different stenosis rates of blood vessels on the fatigue strength and service life of lower limb arterial stent, numerical simulation was conducted for the mechanical behavior of four types of nickel-titanium alloy lower limb arterial stents (Absolute Pro, Complete SE, E-luminexx-B and Pulsar-35) under the action of radial compression, release and pulsating loads, so as to predict the fatigue life and safety of stents at different stenosis rates (0%, 30%, 50% and 70%). The study found that with increased vascular stenosis rate, both the elastic stress and strain of stent tend to increase, while the fatigue strength, service life and safety tend to decrease. When a stent is implanted in a normal blood vessel, its fatigue strength satisfies the requirement of a 10-year service life requirement, with maximum elastic stress and strain occurring on both sides of the connecting ribs at the end of stent. When the vascular stenosis rate is greater than 30%, the fatigue strength of the stent does not meet requirement of a 10-year service life, and fatigue fracture is likely to occur at the most stenotic part of the blood vessel. With increased vascular stenosis rate, the E-luminexx-B stent with the largest width of support had a significant decrease in its service life. The stent whose supporting unit is of symmetric wave peak structure has a longer service life compared with that whose supporting unit is of offset wave peak structure. The revealing of the influence of vascular stenosis rate on the mechanical properties and fatigue life of stents provides theoretical reference for the fracture failure mechanism of stents.