Study on detection and identification model of passive teraherz imaging system for extended target

2010 ◽  
Author(s):  
Hongguang Li ◽  
Hongru Yang ◽  
Liang Yuan ◽  
Baoning Wu
Keyword(s):  
Imaging System ◽  
Detection And Identification ◽  
Extended Target ◽  
Identification Model

scholarly journals A Parasitic Array Receiver for ISAR Imaging of Ship Targets Using a Coastal Radar

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Fabrizio Santi ◽  
Debora Pastina
Keyword(s):  
Ad Hoc ◽  
Imaging System ◽  
Range Resolution ◽  
Bounded Number ◽  
Detection And Identification ◽  
Isar Imaging ◽  
Illegal Activities ◽  
Simulated Analysis ◽  
Parasitic Array ◽  
Array Receiver

The detection and identification of ship targets navigating in coastal areas are essential in order to prevent maritime accidents and to take countermeasures against illegal activities. Usually, coastal radar systems are employed for the detection of vessels, whereas noncooperative ship targets as well as ships not equipped with AIS transponders can be identified by means of dedicated active radar imaging system by means of ISAR processing. In this work, we define a parasitic array receiver for ISAR imaging purposes based on the signal transmitted by an opportunistic coastal radar over its successive scans. In order to obtain the proper cross-range resolution, the physical aperture provided by the array is combined with the synthetic aperture provided by the target motion. By properly designing the array of passive devices, the system is able to correctly observe the signal reflected from the ships over successive scans of the coastal radar. Specifically, the upper bounded interelement spacing provides a correct angular sampling accordingly to the Nyquist theorem and the lower bounded number of elements of the array ensures the continuity of the observation during multiple scans. Anad hocfocusing technique has been then proposed to provide the ISAR images of the ships. Simulated analysis proved the effectiveness of the proposed system to provide top-view images of ship targets suitable for ATR procedures.

scholarly journals Design of thermal imaging continuous-zoom optical system

2021 ◽  
Vol 2127 (1) ◽  
pp. 012070
Author(s):  
A V Kryukov ◽  
Yu Yu Kachurin ◽  
Yu S Datiy
Keyword(s):  
Optical System ◽  
Thermal Imaging ◽  
Imaging System ◽  
Focal Length ◽  
Optical Parameters ◽  
Secondary System ◽  
System A ◽  
Detection And Identification ◽  
Objective System ◽  
Analytical Expressions

Abstract The report tells about the design of a middle wave infrared continuous-zoom imaging optical system. To capture the image in an «eye-type» infrared optical system a multi-element sensor is used. To increase the contrast of the thermal image the sensor is equipped with a cold aperture. The use of an optical system based on the continuous-zoom lens makes it possible to solve the problems of object detection and identification more effectively but requires taking into account some features of varifocal lenses. The optical system being analyzed in the report includes front zoom objective system and secondary imaging system. The front zoom optical system is composed of four groups and provides the focal length that is continuously changed with a large zoom ratio (15–20X) under the condition of a constant total length of the system. The secondary imaging system is designed for zoom system exit stop and sensor cold stop conjugation. The design technique represents analytical expressions and equations to obtain optical parameters of the front and secondary system components and the motion curves for movable groups.

A Model to Predict Range Performance of Imaging System for Extended Target Based on Mininum Resolvable Contrast

2009 ◽  
Vol 29 (6) ◽  
pp. 1552-1556
Author(s):  
金伟其 Jin Weiqi ◽  
高绍姝 Gao Shaoshu ◽  
王吉晖 Wang Jihui ◽  
王霞 Wang Xia ◽  
李力 Li Li ◽  
...  
Keyword(s):  
Imaging System ◽  
Extended Target

Anthropometric and performance measures for the development of a talent detection and identification model in youth handball

2009 ◽  
Vol 27 (3) ◽  
pp. 257-266 ◽  
Author(s):  
Hasan Mohamed ◽  
Roel Vaeyens ◽  
Stijn Matthys ◽  
Marc Multael ◽  
Johan Lefevre ◽  
...  
Keyword(s):  
Performance Measures ◽  
Detection And Identification ◽  
And Performance ◽  
Identification Model

scholarly journals Indonesian Spelling Error Detection and Type Identification Using Bigram Vector and Minimum Edit Distance Based Probabilities

SinkrOn ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 183-190
Author(s):  
Emmy Erwina ◽  
Tommy Tommy ◽  
Mayasari Mayasari
Keyword(s):  
Test Data ◽  
Error Detection ◽  
Edit Distance ◽  
Spelling Error ◽  
Correct Word ◽  
Error Type ◽  
Detection And Identification ◽  
Younger Generation ◽  
Identification Model ◽  
Error Types

Spelling error has become an error that is often found in this era which can be seen from the use of words that tend to follow trends or culture, especially in the younger generation. This study aims to develop and test a detection and identification model using a combination of Bigram Vector and Minimum Edit Distance Based Probabilities. Correct words from error words are obtained using candidates search and probability calculations that adopt the concept of minimum edit distance. The detection results then identified the error type into three types of errors, namely vowels, consonants and diphthongs from the error side on the tendency of the characters used as a result of phonemic rendering at the time of writing. The results of error detection and identification of error types obtained are quite good where most of the error test data can be detected and identified according to the type of error, although there are several detection errors by obtaining more than one correct word as a result of the same probability value of these words.

New Aspects in the Design of Electron Optical Magnification Systems

1972 ◽  
Vol 30 ◽  
pp. 606-607
Author(s):  
Willem H.J. Andersen
Keyword(s):  
Electron Microscope ◽  
Imaging System ◽  
Chromatic Aberration ◽  
Research Tool ◽  
Energy Losses ◽  
Objective Lens ◽  
Theoretical Limit ◽  
Optical Magnification ◽  
Chromatic Aberrations ◽  
High Degree

Electron microscope design, and particularly the design of the imaging system, has reached a high degree of perfection. Present objective lenses perform up to their theoretical limit, while the whole imaging system, consisting of three or four lenses, provides very wide ranges of magnification and diffraction camera length with virtually no distortion of the image. Evolution of the electron microscope in to a routine research tool in which objects of steadily increasing thickness are investigated, has made it necessary for the designer to pay special attention to the chromatic aberrations of the magnification system (as distinct from the chromatic aberration of the objective lens). These chromatic aberrations cause edge un-sharpness of the image due to electrons which have suffered energy losses in the object.There exist two kinds of chromatic aberration of the magnification system; the chromatic change of magnification, characterized by the coefficient Cm, and the chromatic change of rotation given by Cp.

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