發(fā)布時(shí)間：2018-08-23 19:33

【摘要】：人類(lèi)合理開(kāi)發(fā)利用核能過(guò)程中,就開(kāi)始研究核放射源安全問(wèn)題。對(duì)于丟失、被盜放射源等安全事故發(fā)生情況下,如何還原未知核放射源輻射場(chǎng)以及如何在高輻射環(huán)境下,快速搜索并清除散落區(qū)域內(nèi)的核放射性物質(zhì)是核技術(shù)運(yùn)用中重要的安全保障問(wèn)題。對(duì)核安全應(yīng)急響應(yīng)策略具有重大現(xiàn)實(shí)意義。丟失、被盜的核放射性物質(zhì)搜索大多局限于從事核技術(shù)專(zhuān)業(yè)的工作者,借助伽馬射線檢測(cè)儀器或其他射線探測(cè)儀,憑經(jīng)驗(yàn)來(lái)搜索放射源的位置。但由于放射源搜索難度大或者特殊環(huán)境情況下的搜索效率低,放射源危害人們的身體安全等問(wèn)題是制約放射源搜索的技術(shù)發(fā)展瓶頸問(wèn)題。在核能產(chǎn)業(yè)迅猛發(fā)展和核技術(shù)廣泛應(yīng)用的今天,核放射源的安保研究,尤其是未知放射源的智能搜索研究,顯得更加重要。本文從研究核放射源輻射場(chǎng)的物理特性入手,考慮到核輻射場(chǎng)自身的特點(diǎn),利用數(shù)學(xué)構(gòu)造方法,構(gòu)造了稀疏數(shù)據(jù)下具有核放射源特性的輻射場(chǎng)函數(shù)。采用還原的未知放射源輻射場(chǎng)數(shù)據(jù),設(shè)計(jì)了啟發(fā)式智能搜索算法,實(shí)現(xiàn)了計(jì)算機(jī)輔助智能搜索,提出了人機(jī)互動(dòng)模式下放射源搜索技術(shù)路線。有效降低了搜索放射源的輻照風(fēng)險(xiǎn)和搜索成本；有利于快速降低和污染區(qū)域輻射水平；有利于保護(hù)公眾的人身安全和環(huán)境生態(tài)安全。本研究主要從以下四個(gè)方面展開(kāi)：(1)對(duì)未知放射源存在的區(qū)域進(jìn)行進(jìn)行網(wǎng)格劃分,并采集網(wǎng)格節(jié)點(diǎn)數(shù)據(jù)。在充分考慮到輻射場(chǎng)內(nèi)任意點(diǎn)輻射劑量值與放射源距離平方成反比關(guān)系,運(yùn)用數(shù)學(xué)構(gòu)造方法還原放射源輻射劑量場(chǎng),構(gòu)造了網(wǎng)格線上斜率逐段連續(xù)變化的網(wǎng)格線上的輻射劑量曲線,同時(shí)結(jié)合鄰點(diǎn)輻射劑量占優(yōu)方法構(gòu)造了輻射劑量場(chǎng)來(lái)反演還原輻射劑量場(chǎng),得到了具有放射源特征的尖陡的凹函數(shù)輻射場(chǎng),從而得到輻射場(chǎng)內(nèi)任意點(diǎn)近似輻射劑量值。模擬實(shí)驗(yàn)計(jì)算得反演構(gòu)造的輻射場(chǎng)與實(shí)際真實(shí)輻射場(chǎng)誤差3.19%(見(jiàn)P47誤差分析實(shí)驗(yàn)),反演構(gòu)造輻射劑量函數(shù)形態(tài)更具放射源特征,因此構(gòu)造輻射場(chǎng)方法切實(shí)可行且更接近真實(shí)輻射劑量場(chǎng)。提出了數(shù)學(xué)構(gòu)造法反演還原核輻射場(chǎng)的思路。(2)在核放射源存在的區(qū)域范圍,對(duì)放射源搜索區(qū)域進(jìn)行了定義。同時(shí)針對(duì)放射源搜索問(wèn)題中如何判斷搜索到的輻射劑量極大值是否是放射源進(jìn)行了研究,構(gòu)造了適合不同情況的閾值算法理論來(lái)進(jìn)行判斷。以放射源輻射劑量最高處為對(duì)稱的凹函數(shù)特性設(shè)計(jì)的確定放射源判斷的數(shù)學(xué)算法為主。(3)在建立核輻射劑量場(chǎng)的理論基礎(chǔ)上,為了能在較短的時(shí)間內(nèi)快速搜索到未知放射源,本文選用了啟發(fā)式算法,設(shè)計(jì)了線掃搜索算法。鑒于放射源僅出現(xiàn)在輻射劑量極大值點(diǎn)處,改進(jìn)了啟發(fā)式線掃算法,設(shè)計(jì)了僅局部擬合波峰段輻射劑量曲線的二次擬合線掃算法,簡(jiǎn)化了搜索過(guò)程,提高了搜索的運(yùn)行效率；針對(duì)由于數(shù)據(jù)誤讀可能造成放射源搜索失敗,設(shè)計(jì)了三次擬合線掃搜索算法,提高了搜索成功率。同時(shí)模擬實(shí)驗(yàn)驗(yàn)證了線掃算法,二次擬合和三次擬合線掃算法及其優(yōu)化算法均能在合理時(shí)間內(nèi)較好實(shí)現(xiàn)放射源搜索。(4)提出隨機(jī)搜索概率優(yōu)化模型。模仿典型常規(guī)搜索放射源的經(jīng)驗(yàn),并在計(jì)算機(jī)上實(shí)現(xiàn)典型的搜索過(guò)程。將啟發(fā)式搜索思想與隨機(jī)搜索結(jié)合,使得隨機(jī)搜索適應(yīng)實(shí)際搜索中各種復(fù)雜情況,設(shè)計(jì)了帶有自動(dòng)識(shí)別校正數(shù)據(jù)誤讀、大步長(zhǎng)快速搜索以及跳出低輻射劑量區(qū)域等功能的智能隨機(jī)搜索算法。特別對(duì)于多個(gè)放射源并存區(qū)域情況進(jìn)行了深入討論,設(shè)計(jì)了單鏈?zhǔn)胶投噫準(zhǔn)街悄軉l(fā)式隨機(jī)搜索算法。對(duì)于有障礙物的情況,設(shè)計(jì)了具有追蹤輻射劑量極大方向隨機(jī)搜索算法,使得隨機(jī)搜索算法具有較強(qiáng)的適應(yīng)性。最后在計(jì)算機(jī)上模擬了上述多種復(fù)雜情況,利用計(jì)算機(jī)智能搜索處于障礙區(qū)內(nèi)的多點(diǎn)放射源,驗(yàn)證了隨機(jī)搜索算法能有效解決放射源搜索問(wèn)題,較好實(shí)現(xiàn)了計(jì)算機(jī)對(duì)放射源的準(zhǔn)確定位功能。隨機(jī)搜索算法節(jié)約數(shù)據(jù)采集量,降低輻照風(fēng)險(xiǎn),同時(shí)在計(jì)算機(jī)上實(shí)現(xiàn)人機(jī)互動(dòng)智能隨機(jī)搜索。
[Abstract]:In the process of rational development and utilization of nuclear energy, people begin to study the safety of nuclear radiation sources. How to restore the radiation field of unknown nuclear radiation sources and how to quickly search and remove the radioactive materials in scattered areas under high radiation environment are important in the application of nuclear technology in the case of loss and stolen radioactive sources. Safety and security issues. It is of great practical significance for nuclear safety emergency response strategies. Lost, the search for stolen nuclear and radioactive materials is mostly confined to workers engaged in nuclear technology, with the help of gamma ray detection instruments or other ray detectors, to search the location of radioactive sources by experience. However, the search for radioactive sources is difficult or special. Nowadays, with the rapid development of nuclear energy industry and the wide application of nuclear technology, the security research of nuclear radioactive sources, especially the intelligent search of unknown radioactive sources, is becoming more and more important. The physical properties of radiation field of nuclear radiation source are studied. Considering the characteristics of nuclear radiation field itself, the radiation field function with nuclear radiation source characteristics under sparse data is constructed by using mathematical construction method. This paper puts forward the technical route of searching radioactive sources under man-machine interaction mode, which effectively reduces the radiation risk and searching cost of searching radioactive sources, helps to rapidly reduce and pollute the radiation level in the region, and helps to protect the public's personal safety and environmental ecological safety. The radiation dose field of the radiation source is restored by mathematical construction method, and the radiation dose curve on the grid line with continuous gradient variation is constructed. A radiation dose field is constructed by combining the adjacent radiation dose dominance method to retrieve the reduced radiation dose field, and the sharp concave function radiation field with the characteristics of the radiation source is obtained. The approximate radiation dose value at any point in the radiation field is obtained. The error between the retrieved radiation field and the actual radiation field is 3.19% (see P47). The error analysis experiment shows that the inversion of the structure radiation dose function is more characteristic of radiation source, so the method of constructing radiation field is feasible and closer to the real radiation dose field. This paper studies how to judge whether the maximum radiation dose is a radioactive source in the problem of searching for radioactive sources, and constructs a threshold algorithm theory suitable for different situations to judge whether the maximum radiation dose is a radioactive source. Based on the theory of radiation dose field, in order to search the unknown radiation source quickly in a short time, this paper chooses the heuristic algorithm and designs a line scan algorithm. The sub-fitting line sweeping algorithm simplifies the search process and improves the search efficiency; aiming at the possible failure of radioactive source search due to data misreading, a cubic fitting line sweeping search algorithm is designed to improve the search success rate. Simultaneously, the line sweeping algorithm, the quadratic fitting and the cubic fitting line sweeping algorithm and its optimization algorithm are verified by simulation experiments. (4) A random search probability optimization model is proposed, which imitates the experience of typical conventional search for radioactive sources and realizes the typical search process on a computer. Intelligent random search algorithm with the functions of automatic identification and correction of data misreading, large step-size fast search and jumping out of low radiation dose area is designed. Especially for the case of multiple radiation sources coexisting in the region, a single-chain and multi-chain intelligent heuristic random search algorithm is designed. Random search algorithm for maximum direction of radiation dose tracing makes the random search algorithm have strong adaptability. Finally, the above-mentioned complex situations are simulated on a computer, and multi-point radiation sources in obstacle areas are searched intelligently by computer. The results show that the random search algorithm can effectively solve the problem of radiation source searching and better realize the design. Random search algorithm saves the amount of data acquisition and reduces the risk of radiation. At the same time, it realizes intelligent random search of man-machine interaction on computer.
【學(xué)位授予單位】：南華大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：TL73

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本文編號(hào)：2199695