Digital Image Processing

In this paper we give a tutorial overview of the field of digital image processing. Following a brief discussion of some basic concepts in this area, image processing algorithms are presented with emphasis on fundamental techniques which are broadly applicable to a number of applications. In addition to several real-world examples of such techniques, we also discuss the applicability of digital image processing to one particular field, that of medical radiography.     

Simultaneous Model Selection,Robust Data Reconciliation and Outlier Detection with Swarm Intelligence in a Thermal Reactor Power calculation

Data Reconciliation (DR) and Gross Errors Detection (GED) are techniques of increasing interest in Nuclear Power Plants and used in order to keep Mass and Energy balance into account. These Techniques have been extensively studied in Chemical and Petrochemical Industry due to its benefits, which include closing the mass and energy balance and the yield of promising financial results. Many techniques were developed to solve Data Reconciliation and Outlier Detection, some of them use, for example, Quadratic Programming, Lagrange Multipliers, Mixed-Integer NonLinear Programming and others use Evolutionary Algorithms like Genetic Algorithms (GA) and Particle Swarm Optimization (PSO). Nowadays, Robust Statistics is also increasing in interest and it is being used in order to surpass some methods limitation, e.g., assuming that the errors are Normally Distributed, which does not always reflects real problems situation. In this paper we present a novel method to perform simultaneously: (a) the tuning of the Hampel’s Three Part Redescending Estimator (HTPRE) constants; (b) the Robust Data Reconciliation and (c) the Gross Error Detection. The automatic tuning procedure is based on the minimization of the Robust Akaike Criteria and the Particle Swarm Algorithm is used as a global optimization method. Simulations were made considering a nonlinear process commonly used as a benchmark by several authors and also in calculating the Thermal Reactor Power based on a simplified example. The results show the potential use of the technique even in an on-line Process to solve Data Reconciliation and Gross Error Detection problem and do not need a separate procedure to tune first redescending estimator and later perform the DR and GED method.     

数字化多道脉冲幅度分析技术研究

多道脉冲幅度分析技术正在朝数字化方向发展,基于数字信号处理技术的数字化多道具有脉冲处理能力强、速度快、稳定性高和灵活性强等特点。文章分析了数字核脉冲处理关键技术,利用MATLAB完成了梯形成形、数字基线估计、数字极零零极补偿、极零点识别等核心算法的模拟。给出了数字化多道初步总体设计方案,探讨了工程没计中的关键技术问题,为研制国产数字化核谱仪打下了基础。     

Recent developments in data mining and soft computing for JET with a view on ITER

In order to handle the vast amount of information collected by JET diagnostics, which can exceed 10 Gbytes of data per shot, a series of new soft computing methods are being developed. They cover various aspects of the data analysis process, ranging from information retrieval to statistical confidence and machine learning. In this paper some recent developments are described. History effects in the plasma evolution leading to disruptions have been investigated with the use of Artificial Neural Networks. New image processing algorithms, based on optical flow techniques, are being used to derive quantitative information about the movement of objects like filaments at the edge of JET plasmas. Adaptive filters, mainly of the Kalman type, have been successfully implemented for the online filtering of MSE data for real time purposes.     

Managing patient dose in digital radiology. A report of the International Commission on Radiological Protection

Digital techniques have the potential to improve the practice of radiology but they also risk the overuse of radiation. The main advantages of digital imaging, i.e. wide dynamic range, post processing, multiple viewing options, and electronic transfer and archiving possibilities, are clear but overexposures can occur without an adverse impact on image quality. In conventional radiography, excessive exposure produces a 'black' film. In digital systems, good images are obtained for a large range of doses. It is very easy to obtain (and delete) images with digital fluoroscopy systems, and there may be a tendency to obtain more images than necessary. In digital radiology, higher patient dose usually means improved image quality, so a tendency to use higher patient doses than necessary could occur. Different medical imaging tasks require different levels of image quality, and doses that have no additional benefit for the clinical purpose should be avoided. Image quality can be compromised by inappropriate levels of data compression and/or postprocessing techniques. All these new challenges should be part of the optimisation process and should be included in clinical and technical protocols. Local diagnostic reference levels should be re-evaluated for digital imaging, and patient dose parameters should be displayed at the operator console. Frequent patient dose audits should occur when digital techniques are introduced. Training in the management of image quality and patient dose in digital radiology is necessary. Digital radiology will involve new regulations and invoke new challenges for practitioners. As digital images are easier to obtain and transmit, the justification criteria should be reinforced. Commissioning of digital systems should involve clinical specialists, medical physicists, and radiographers to ensure that imaging capability and radiation dose management are integrated. Quality control requires new procedures and protocols (visualisation, transmission, and archiving of the images).     

核信号数值仿真方法的研究及应用

提出并建立了一种数值仿真方法,通过计算机模拟,生成各种数字化核信号波形,以此作为工具开展核信号数字处理方法的研究.通过准高斯滤波、梯形滤波和匹配滤波算法对数字核信号处理结果的研究与比较表明,提出的方法是准确而可行的.     

基于最优化线抽样法的XAPR自然循环功能失效研究与分析

针对多维不确定性参数、小失效概率的功能可靠性分析,提出了一种优化线抽样的可靠性分析方法。该方法采用遗传算法求解约束条件的优化模型来寻求最优化重要方向,进而得到失效概率的高效估计。以西安脉冲堆（XAPR）自然循环冷却堆芯能力的可靠性评价为例,考虑模型与输入参数的不确定性,对中破口失水事故下的自然循环功能失效概率进行了量化分析。结果表明：与其他概率评估方法相比,本文方法具有很高的计算效率,同时又能保证很好的计算精度;对隐式非线性的功能可靠性分析是有效可行的,具有很强的适应性。     

Digital pulse processor for ion beam microprobe imaging

Capabilities of spectroscopic ion beam analysis (IBA) techniques that are available in ion microprobe facilities can be greatly improved by the use of digital pulse processing. We report here development of a digital multi parameter data acquisition system suitable for IBA imaging applications. Input signals from charge sensitive preamplifier are conditioned by using a simple circuit and digitized with fast ADCs. The digitally converted signals are processed in real time using FPGA. Implementation of several components of the system is presented.     

钴-60铁路货车在线检测系统研制

研制了钴 6 0铁路货车在线检测系统。采用辐射成像原理在货运列车通过检测通道时自动获取每节车厢的辐射投射图像 ,再根据对应的海关报关信息 ,利用数字图像处理技术查看车厢内货物是否与申报结果相符。该系统已在满洲里海关投入使用。     

A new digital pulse processing method for 2πa and 2πβemitter measurement

Digital pulse processing has developed rapidly during recent years. Moreover, it has been widely applied in many fields. In this study, we introduce a digital pulse processing method for 2πa and 2πβemitter measurement. Our digital pulse processing method for 2πa and 2πβemitter measurement is comprised of a field-programmable gate-array-based acquisition card and a pulse-height anal-ysis routine. We established two channels (one for the a emitter and one for theβemitter) on an acquisition board using an analog-to-digital converter with a 16-bit resolu-tion at a speed of 100 million samples per second. In this study, we used captured and stored data to analyze emis-sion rate counts and spectrums. The method we established takes into account noise cancelation, dead-time correction, background subtraction, and zero-energy extrapolation. We carefully designed control procedures in order to simplify pulse-width fitting and threshold-level setting. We trans-mitted data and commands through a universal serial bus between the acquisition board and the computer. The results of our tests prove that our method performs well in pulse reconstruction fidelity and amplitude measurement accuracy. Compared with the current standard method for measuring 2πa and 2πβ emission rates, our system demonstrates excellent precision in emission rate counting.     

Image Processing in Nuclear Medicine

A survey of various image processing techniques as applied to images in nuclear medicine is presented. These have been classified as procedures to improve detectability, to correct for distortion, to compress, and to aid automation. On evaluation, rather disappointing results fromconventional image'enhancing' techniques have been found. On the other hand, the use of image 'transforming' procedures is highly satisfactory and of increasing importance in this field. This survey has been prepared for the image processor who knows little of nuclear medicine, or the nuclear medicine practitioner who knows little of image processing.     

Digital Signal Processing for Mass Identification in a $4pi$-Detector, Using Time of Flight Measurement

CHIMERA is the only 4 pi-multidetector, used in intermediate nuclear physics experiments, able to perform mass identification of the reaction products. To this purpose, it employs time of flight measurements done with traditional time to digital converters. In order to improve the resolution in mass identification, we have applied digital signal processing to time of flight measurements. This paper presents the methodology for data analysis, the adopted algorithms and the results obtained at different sampling frequencies (mass identification up to A = 33 for the reaction products produced by a 20.5 MeV/u ²⁰Ne beam on ²⁷Al target).     

基于示波器的数字化能谱仪构建

针对正电子寿命测量中能量窗口调节较为繁琐的特点,论文基于高分辨数字示波器LeCroy HDO6104和PC,使用MATLAB软件搭建了数字化能谱测量系统,可对BaF_2探测器阳极输出信号进行实时处理和分析。通过对比最大脉冲幅度、曲线拟合与波形面积等方法,选出了最佳的能谱测量方法,实现了数字化的~(22)Na能谱测量及能量窗口调节功能。     

Reliability assessment method for NPP digital I&C systems considering the effect of automatic periodic tests

Since digital technologies have been improved, the analog systems in nuclear power plants (NPPs) have been replaced with digital systems. Recently, new NPPs have adapted various kinds of digital instrumentation and control (I&C) systems. Even though digital I&C systems have various fault-tolerant techniques for enhancing the system availability and safety compared to conventional analog I&C systems, the effects of these fault-tolerant techniques on system safety have not been properly considered yet in most probabilistic safety assessment models. Therefore, it is necessary to develop the safety evaluation method for digital I&C systems with consideration of fault-tolerant techniques. Among the various issues in the safety model for digital I&C systems, one of the important issues is how to exclude the duplicated effect of fault-tolerant techniques implemented at each hierarchy level of the system. The exact relation between faults and fault-tolerant techniques should be identified in order to exclude this duplicated effect. In this work, the relation between faults and fault-tolerant techniques are identified using fault injection experiments. As an application, the proposed method was applied to a module of a digital reactor protection system.     

The BaBar Data Reconstruction Control System

The BaBar experiment is characterized by extremely high luminosity and very large volume of data produced and stored, with increasing computing requirements each year. To fulfill these requirements a control system has been designed and developed for the offline distributed data reconstruction system. The control system described in this paper provides the performance and flexibility needed to manage a large number of small computing farms, and takes full benefit of object oriented (OO) design. The infrastructure is well isolated from the processing layer, it is generic and flexible, based on a light framework providing message passing and cooperative multitasking. The system is distributed in a hierarchical way: the top-level system is organized in farms, farms in services, and services in subservices or code modules. It provides a powerful finite state machine framework to describe custom processing models in a simple regular language. This paper describes the design and evolution of this control system, currently in use at SLAC and Padova on$sim$450 CPUs organized in nine farms.     

A multi-channel real-time digital integrator for magnetic diagnostics in HL-2A tokamak

A novel full-digital integrator has been developed for the magnetic diagnostics in HL-2A. Based on the pipeline processing of the field-programmable gate array and high-speed PCI extensions for instrumentation platform, the digital integrator has realized octal-channel10-k Hz real-time integration and data transmission. In order to reduce the integration drift, a 24-bit analog-todigital converter and simple analog processing circuits are applied for high-precision sampling, while certain correction algorithms are used to minimize the drift. With simple and highly integrated circuits and high-performance digital processor, the digital integrator is of high stability and functional expansibility which greatly simplifies the operation procedure. The digital integrator has been tested in the plasma discharge experiments, and the experimental results have confirmed that the drift performance and accuracy of the digital integrator could fully meet the requirements of HL-2A.     

基于FPGA+DSP的核信号数字时间谱仪设计

针对核电子学中核脉冲信号的高速实时数字化处理,设计了基于FPGA+DSP的两通道核信号数字时间谱仪。该实验平台基于数字恒比定时(dCFD)原理,采用高速运放和ADC进行模拟信号成型采样,数字信号送入FPGA完成波形判选、数据缓冲、FIR滤波和基线恢复,利用DSP实时信号重构和函数定时,通过USB2.0接口与上位机通信。该系统的主要特点是具有模数电路的高度集成、数字信号的实时运算,接近模拟定时的精度。     

EPICS interface to Libera electron beam position monitor

SSRF diagnostics system will adopt a new generation digital electron beam position processor,Libera,as the signal condition,signal processing and data acquisition device for beam position monitor.In order to provide a uniform data and control interface for users,we developed an EPICS interface based on Control System Programming Interface(CSPI)layer,allowing the performance of the electron beam to be monitored through EPICS channels.In this interface a new record type for BPM was defined and its associated support routines were implemented.     

The Use of Computers for Image Processing in Nuclear Medicine

A survey of various image processing techniques as applied to images in nuclear medicine is presented. These may be classified as procedures to improve detectability, to correct for distortion, to compress, to quantitate and to aid automation. On evaluation, although rather disappointing results from conventional image 'enhancing' techniques have been found, the use of various image 'transforming' procedures seems highly satisfactory and, in particular using array processors, of increasing importance in this field.