Non-Bayesian Image Feature Detectors
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In this paper non-Bayesian and heuristic approaches are applied to the well known problem of image segmentation. The two subproblems in segmentation that were considered were region merge and line detection. For the region merge problem, a comparison was made between the classical Bayes and fuzzy set based approach. Simulations, using a "block world" type real image, were implemented in ZETALISP on the Symbolics 3675 computer. They contrasted the proposed region merge method with the classical implementations. The performance measures of the classical line detection problem, using the Hough transform, are reinterpreted in a non-traditional framework using fuzzy sets and heuristics. Several alternative real-time optical Hough transform schemes are presented as well.Keywords:
Feature (linguistics)
In this paper, the disadvantages of using the Hough transform as a detector have been considered in a search radar. To illustrate the effect of these disadvantages on the performance of the detector, its performance has been compared with the optimum detectors. To do this, the Average Likelihood Ratio detector has been extracted for detecting a target line with a known normal parameter pair in the search environment. Then, the performance of this detector has been compared with the Hough detector by extracting their Receiver Operation Characteristics. The results of this comparison, which has been done through simulations, show that the Average Likelihood Ratio detector has a better performance.
Hough Transform
Line (geometry)
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False alarm
Sample (material)
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V-detector algorithm is unable to guarantee a large coverage for generated detector.The shortcoming usually results in a large number of detectors in the detector sets and low detection efficiency.An optimized V-detector algorithm was proposed.In the optimized algorithm,a detector was generated on the basis of a randomly chosen uncovered non-self sample,and the detector generation process ensured the detector covered the non-self sample and extended the detector's coverage by determining the detector's center and detection radius reasonably.Meanwhile,hypothesis testing process was used to estimate the coverage of a detector set,and hypothesis testing process was integrated with detector generation process to ensure the generated detector set fully covered the non-self region,and reduced the number of detectors in the detector set.Experimental results indicate that compared with the V-detector algorithm,the optimized algorithm generates a much smaller detector set and increases the detection efficiency.
Sample (material)
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A new architecture for 3D silicon radiation detectors is proposed which simplifies the fabrication process and avoids the limitations of 3D detectors technology. The detector consists in a three-dimensional array of electrodes that penetrate into the detector bulk. The geometry of the detector is such that a central anode is surrounded by four cathode contacts. This geometry gives a uniform electric field with the maximum drift and depletion distance set by the electrode spacing rather than detector thickness. This structure is similar to a conventional 3D detector, but has a simpler fabrication process. The technological and the electrical simulations together with the fabrication steps of this new detector configuration are reported in this paper.
X-ray detector
Particle detector
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Monte Carlo simulation was used to study the effect detector scatter has on the decoding accuracy of a depth of interaction (DOI) detector module and on the quantitative imaging characteristics of a DOI detector system. The detector module consisted of a 4/spl times/4 array of detector units, Each unit consisted of a 2/spl times/2 block of 2/spl times/2/spl times/20 mm LSO crystals. The detector units use light sharing and ratio information to estimate DOI. The detector system consisted of 24 detector modules. Positioning methods using different criteria to select the first interaction point in a detector module to improve decoding accuracy were investigated (e.g., maximum energy, second maximum, minimum DOI). Selecting the detector unit corresponding to the minimum DOI provided the best decoding accuracy for photons entering perpendicular to the detector. However, for photons entering at large angles of incidence (e.g., 30 degrees) the maximum energy selection criterion performed the best. The average DOI offset due to scatter within a detector unit was 1.7 mm. Detector scatter only had a minimal effect on the image resolution of the simulated DOI detector system. It had a slightly larger effect on the quantitative recovery of small regions of interest.
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The time response characteristic of the detector is crucial in radiation imaging systems. Unfortunately, existing parallel plate ionization chamber detectors have a slow response time, which leads to blurry radiation images. To enhance imaging quality, the electrode structure of the detector must be modified to reduce the response time. This paper proposes a gas detector with a grid structure that has a fast response time. In this study, the detector electrostatic field was calculated using COMSOL, while Garfield++ was utilized to simulate the detector’s output signal. To validate the accuracy of simulation results, the experimental ionization chamber was tested on the experimental platform. The results revealed that the average electric field intensity in the induced region of the grid detector was increased by at least 33%. The detector response time was reduced to 27% –38% of that of the parallel plate detector, while the sensitivity of the detector was only reduced by 10%. Therefore, incorporating a grid structure within the parallel plate detector can significantly improve the time response characteristics of the gas detector, providing an insight for future detector enhancements.
Helium ionization detector
Discharge ionization detector
SIGNAL (programming language)
Response time
Particle detector
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A new type of three-dimensional (3D) detector, namely 3D-Open-Shell-Electrode Detector (3DOSED), is proposed in this study. In a 3DOSED, the trench electrode can be etched all the way through the detector thickness, totally eliminating the low electric field region existed in the conventional 3D-Trench-Electrode detector. Full 3D technology computer-aided design (TCAD) simulations have been done on this novel silicon detector structure. Through comparing of the simulation results of the detector, we can obtain the best design of the 3SOSED. In addition, simulation results show that, as compared to the conventional 3D detector, the proposed 3DOSED can improve not only detector charge collection efficiency but also its radiation hardness with regard to solving the trapping problem in the detector bulk. What is more, it has been shown that detector full depletion voltage is also slightly reduced, which can improve the utility aspects of the detector. When compared to the conventional 3D detector, we find that the proposed novel 3DOSED structure has better electric potential and electric field distributions, and better electrical properties such as detector full depletion voltage. In 3DOSED array, each pixel cell is isolated from each other by highly doped trenches, but also electrically and physically connected with each other through the remaining silicon bulk between broken electrodes.
Particle detector
Radiation hardening
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Spectrum analyzer is one of the radio frequency measuring instruments in common use.Appropriate detector types should be chosen to analyze and measure a variety of signals to show their characteristics correctly,the results would be inaccurate or absolutely wrong when inappropriate detector types are chosen.Various kinds of detector types of spectrum analyzer are introduced,the features and applications of sample detector,max peak detector,min peak detector,auto peak detector,normal detector,average detector,RMS detector and quasi-peak detector are analyzed in detail,the differences among them are concluded.
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