scholarly journals BLIND CONTRAST ENHANCEMENT ASSESSMENT BY GRADIENT RATIOING AT VISIBLE EDGES

2011 ◽  
Vol 27 (2) ◽  
pp. 87 ◽  
Author(s):  
Nicolas Hautière ◽  
Jean-Philippe Tarel ◽  
Didier Aubert ◽  
Éric Dumont
Keyword(s):  
Image Quality ◽  
Contrast Enhancement ◽  
Image Quality Assessment ◽  
Weather Conditions ◽  
Reference Image ◽  
Tone Mapping ◽  
Adverse Weather Conditions ◽  
Adverse Weather ◽  
Before And After ◽  
Visibility Enhancement

The contrast of outdoor images acquired under adverse weather conditions, especially foggy weather, is altered by the scattering of daylight by atmospheric particles. As a consequence, differentmethods have been designed to restore the contrast of these images. However, there is a lack of methodology to assess the performances of the methods or to rate them. Unlike image quality assessment or image restoration areas, there is no easy way to have a reference image, which makes the problem not straightforward to solve. In this paper, an approach is proposed which consists in computing the ratio between the gradient of the visible edges between the image before and after contrast restoration. In this way, an indicator of visibility enhancement is provided based on the concept of visibility level, commonly used in lighting engineering. Finally, the methodology is applied to contrast enhancement assessment and to the comparison of tone-mapping operators.

Effect of Stern Flaps on Powering Performance of the FFG-7 Class

1993 ◽  
Vol 30 (01) ◽  
pp. 39-50
Author(s):  
William L. Cave ◽  
Dominic S. Cusanelli
Keyword(s):  
Fuel Consumption ◽  
Weather Conditions ◽  
Full Scale ◽  
Wave System ◽  
Test Results ◽  
Adverse Weather Conditions ◽  
Adverse Weather ◽  
Before And After ◽  
The Cost ◽  
Percent Decrease

The effect of a stern flap on the powering performance and annual fuel consumption of an FFG-7 Oliver Hazard Perry Class Guided Missile Frigate is presented. Analytical analysis using free surface potential flow theory was conducted to evaluate the flow on the afterbody of the ship. Model tests were conducted to determine the optimum geometrical characteristics of the stern flap. Based on the analytical and model test results, a stern flap was retrofitted to an FFG-7 Class frigate, and full-scale results on powering performance were collected. Results of model powering experiments showed that the flap, set at 10 deg trailing edge down, decreased the delivered power by 8.4 percent at 26 knots, and provided for a 3.8 percent decrease in annual fuel consumption. This decrease in annual fuel consumption places the payback period on the cost of the flap installation at only 10 months. The full-scale comparison of the flap's effectiveness was marred by adverse weather conditions and differences in the pre-and post-flap ship configurations. However, observations of the full-scale stern wave system, before and after the installation of the stern flap, lead the authors to conclude that the flap will produce a larger decrease in delivered power at full scale than shown by the model experiments.

scholarly journals A HIGH-FIDELITY ARTIFICIAL AIRPORT ENVIRONMENT FOR SESAR APOC VALIDATION EXPERIMENTS

2017 ◽  
Vol 8 (1) ◽  
pp. 31-50 ◽  
Author(s):  
Florian Piekert ◽  
Nils Carstengerdes ◽  
Sebastian Schier ◽  
Reiner Suikat ◽  
Alan Marsden
Keyword(s):  
Situation Awareness ◽  
Weather Conditions ◽  
High Fidelity ◽  
Airport Management ◽  
Traffic System ◽  
Adverse Weather Conditions ◽  
Artificial Environment ◽  
Wide Range ◽  
Adverse Weather ◽  
Before And After

Europe’s SESAR Program develops a wide range of solutions to increase the performance of the Air Traffic System. At airport level, the Airport Operations Center (APOC) is expected to provide the most benefit in adverse weather conditions, being the ultimate communication platform to pursue the Total Airport Management (TAM) Collaborative Decision Making Process. It will increase mutual and common situation awareness and allows the joint definition and implementation of the operational strategy. The assessment of APOC benefits in a live airport environment is rather limited and requires implementation and “right” weather and traffic situations. This work argues for validation trials in high fidelity artificial airport environments as a more reliable and less costly alternative which allows comparison between operations before and after implementation of new solutions. Based on requirements provided by SESAR concept documentation and from live operations this work presents an approach for such a high fidelity artificial environment.

No-Reference Image Quality Assessment Based on Multi-Order Gradients Statistics

2020 ◽  
Vol 64 (1) ◽  
pp. 10505-1-10505-16
Author(s):  
Yin Zhang ◽  
Xuehan Bai ◽  
Junhua Yan ◽  
Yongqi Xiao ◽  
C. R. Chatwin ◽  
...  
Keyword(s):  
Neural Network ◽  
Image Quality ◽  
Quality Assessment ◽  
Image Quality Assessment ◽  
Assessment Method ◽  
Image Distortion ◽  
Image Feature ◽  
Reference Image ◽  
Gradient Magnitude ◽  
Distortion Type

Abstract A new blind image quality assessment method called No-Reference Image Quality Assessment Based on Multi-Order Gradients Statistics is proposed, which is aimed at solving the problem that the existing no-reference image quality assessment methods cannot determine the type of image distortion and that the quality evaluation has poor robustness for different types of distortion. In this article, an 18-dimensional image feature vector is constructed from gradient magnitude features, relative gradient orientation features, and relative gradient magnitude features over two scales and three orders on the basis of the relationship between multi-order gradient statistics and the type and degree of image distortion. The feature matrix and distortion types of known distorted images are used to train an AdaBoost_BP neural network to determine the image distortion type; the feature matrix and subjective scores of known distorted images are used to train an AdaBoost_BP neural network to determine the image distortion degree. A series of comparative experiments were carried out using Laboratory of Image and Video Engineering (LIVE), LIVE Multiply Distorted Image Quality, Tampere Image, and Optics Remote Sensing Image databases. Experimental results show that the proposed method has high distortion type judgment accuracy and that the quality score shows good subjective consistency and robustness for all types of distortion. The performance of the proposed method is not constricted to a particular database, and the proposed method has high operational efficiency.

scholarly journals Ship Handling in Unprotected Waters: A Review of New Technologies in Escort Tugs to Improve Safety

2021 ◽  
Vol 2 (1) ◽  
pp. 46-62
Author(s):  
Santiago Iglesias-Baniela ◽  
Juan Vinagre-Ríos ◽  
José M. Pérez-Canosa
Keyword(s):  
High Performance ◽  
New Technologies ◽  
Weather Conditions ◽  
Hull Form ◽  
Best Available Technologies ◽  
Adverse Weather Conditions ◽  
Adverse Weather ◽  
New Type ◽  
Technological Challenge ◽  
And Performance

It is a well-known fact that the 1989 Exxon Valdez disaster caused the escort towing of laden tankers in many coastal areas of the world to become compulsory. In order to implement a new type of escort towing, specially designed to be employed in very adverse weather conditions, considerable changes in the hull form of escort tugs had to be made to improve their stability and performance. Since traditional winch and ropes technologies were only effective in calm waters, tugs had to be fitted with new devices. These improvements allowed the remodeled tugs to counterbalance the strong forces generated by the maneuvers in open waters. The aim of this paper is to perform a comprehensive literature review of the new high-performance automatic dynamic winches. Furthermore, a thorough analysis of the best available technologies regarding towline, essential to properly exploit the new winches, will be carried out. Through this review, the way in which the escort towing industry has faced this technological challenge is shown.

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