利用MONTECARLO方法分析高能电子加速器中中子引起的感生放射性——微观分析

在高能电子加速器中，高能电子与物质相互作用产生电磁簇射，生成的高能光子与 介质发生光核反应，其后的中子、介子又引发核反应，并引发感生辐射场.本系列文章利用 Monte Carlo方法分析了高能电子加速器中中子引起的感生放射性以及对加速器周围环境的 影响，对于制定关于停机后等待时间的规定具有指导性意义.在微观上利用多步动力学模型 （Many Stage Dynamical Model，MSDM）计算了中子与不同靶材Fe、Cu、Ni的辐射损伤总截 面，然后计算了能量为10、140和700 MeV的中子与加速器相互作用所产生的放射性同位素的 分布及生成截面，并且对3种情况进行了比较和分析.     

低能电子加速器的感生放射性

运行在１０ＭｅＶ能量以上的放射治疗和工业辐照用的电子加速器，均可能产生感生放射性，其强度取决于加速电子能量，束功率和被照材料的类型。电子能量在阈能或近似于２５ＭｅＶ之间，中子基本上产生于“巨光核共振”。医用加速器的Ｘ射线靶，固定和可变准直辐照容器等也是感生放射性的主要来源。     

正确认识天然石材的放射性

介绍了我国天然石材放射性的主要来源和放射性水平，以及应用天然石材装饰室内所致辐射对人体健康产生的不良影响，结合实际情况提出正确选择天然石村的方法，提出了加强对天然石材产品使用管理的相关建议。     

建筑石材的绿色化选用

石材在建筑上的应用越来越广泛，然而由于人们普遍缺乏对石材性能的全面认识，而使得在选择和使用石材时往往形成误区，产生危害。本文在倡导人们选择和使用绿色石材的同时，主要从石材品种、色彩花纹、规格尺寸以及使用寿命等四个方面对其绿色化选用问题进行了探讨。     

正确认识和防护日常天然放射性辐射

天然放射性辐射客观存在于我们日常生存环境空间中,我们需要掌握正确防护方法,免受不必要的辐射照射,以确保自身生命健康安全。辐射是一种以波、粒子或光子的能量束形式传播的能量,分为电离辐射和非电离辐射。天然放射性辐射对人体的照射分为内照射和外照射。它一是来源于外层空间的宇宙射线,二是来源于地壳中放射性物质产生的放射性辐射。防护要针对岩石和土壤中的高放射性物质产生的辐射及室内放射性物质产生的辐射而采取不同的防护方法和措施,从而有效控制和降低其对人体的伤害。     

图象处理中不等精度观测数据的等概率归一法

不等精度的观测数据可能对图象产生较大的干扰，等概率归一法是建立在概率统计理论基础上的，适合于对任何服从正态分布的随机变量做归一化处理。归一化以了从同一正态分布，可以减少或消除不等精度的干扰，突出图象中的有用信息。     

高放废物地质处置库安全评价的地球化学天然类比研究

某铀矿床中水－岩反应的时间范围和强度，可通过对铀天然衰变系放射性不平衡的研究得到半定量化。该铀矿床在形成５１Ｍａ以来，由于水－岩反应较弱，矿石中铀系核素并未发生远距离迁移。铀矿体及近矿岩石至今仍基本处于化学封闭状态。虽然岩石裂隙附近局部发生核素微弱迁移和沉淀，但由于裂隙细小且大多充填粘土等，向上迁移不足３５ｍ，且仅发生在于１０６～１０４ａ及至今时段内。类比研究结果表明，在无开启断裂的含裂隙花岗岩中处置高放废物是安全的     

环境中的放射性污染及其危害

声、光、电(无线电电磁波)、热和放射性,已经成为环境中最为重要的五个物理性污染因子。人类活动产生的噪声污染,光污染,电磁波污染和热污染,已经对环境产生了普遍而显著的不良影响,成为当前严重的社会公害。然而,人为活动产生的放射性污染,除了原子弹、氢弹爆炸,核电厂爆炸事故以外,在通常情况,一般不会对公众造成危害。天然放射性,是构成环境中的放射性本底的物质基础,对人体无害。天然的放射性污染,微乎其微,对环境中的放射性本底没有显著影响,对人类也不构成危害。环境中的放射性污染,远不如光污染,噪声污染,电磁波污染和热污染问题那么严重,那么迫在眉睫、亟待解决。但是,世界上超级大国核武器库中的原子弹、氢弹的数量,足以把整个地球毁灭十次以上。世界上核电站的数量越来越多,核事故时有发生。放射性污染对人类生命和健康构成的潜在威胁,有增无减。天灾人祸,核灾难、核事故,在所难免。为了预防和控制核灾难、核事故的发生,确保我们生存环境的安全,研究放射性的基本物理性质和特征,了解放射性污染及其防护的基本知识,是十分必要的。     

信号自控显示在放射性测量中的应用

为了使在信号测量中省电，本文提出信号自控显示方法，并设计Ｆ－ＳＴ组合延时电路，以解决因用这个方法而产生的计数不稳定性问题。     

伽马能谱系统的改装及应用

对ＧＲＳＡＳ－８０油田岩样伽马能谱分析系统进行了改装，改装后使命名ＧＰＹＳ－１，在新系统下进行了伽马能谱解析工作，并用效率法求解天然放射性核活度，采用标准计量法给出某口井的测量结果。实验应用表明，经过改装后的系统的许多指标已接近国外同类仪器指标，并自行设计出解析软件。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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