强流加速器束晕控制中填充因子对束粒子密度的影响

运用PIC多粒子模拟程序，采用延迟反馈控制法，研究了离子束在运行过程中粒子分布情况．通过分析比较，得到了对束晕进行有效控制后的粒子分布规律，为强流加速器的应用提供了有用的参考．     

强流离子束物理问题及其束晕-混沌的控制方法

强流离子束在国防和国民经济领域中有着极其重要的广泛的应用和发展前景。特别是强流加速器驱动的放射性洁净核能系统。比常规核电更安全、更干净、更便宜，成为20世纪90年代以来国内外该领域的研究热点。但是，处理强流束产生的复杂时空束晕-混沌现象已经成为强流离子束应用中的关键技术之一，需要有效地控制束晕才能确保强流离子束的许多重要应用。在此对强流离子束的主要用途、物理技术问题、宏观粒子模拟的基本方法，尤其是束晕-混沌的控制方法的研究进展，进行简要评述，并指出今后的研究方向。     

束晕-混沌的复杂性、控制方法及应用

 粒子加速器中束流传输系统是由许多电磁聚焦单元为节点组成的复杂网络,强流粒子束在其束流传输网络系统中产生特有的束晕-混沌现象,是一种奇特的复杂性问题,是一个令人关注的、极其重要的课题。本文概述混沌王国里这个特殊的束晕-混沌的复杂性、物理机理、控制方法和实际应用。     

发现的引擎：一个世纪以来粒子加速器的发展

加速器物理学领域非常活跃，发达国家与发展中国家每年都在粒子物理学研究上花费几十亿美元。它是一门纯科学，不仅对于理解粒子物理，而且对于理解天文学和宇宙学具有重要的意义。本书第一次按年代记载了粒子加速器的发展，从静电加速器、线性加速器及回旋加速器的发明直到当今的电子对撞机，它还涉及了以医学为目的以及在工业应用中利用加速器作为x射线源的许多应用。作者指出了推动应用物理与工程领域进步的决定性发现，介绍了做出这些发现的人们，了解了他们使用的方法。粒子加速器利用了当代最先进技术的每一个方面，并且将其发挥到极致，同时它本身也对这些技术作出了贡献。这完全是一个传奇，就象人类在一个世纪之前掌握运输与通讯技术一样引人入胜。     

含黏性力最速降线问题的最优化解法及其在ADS设计中的应用

为优化加速器驱动次临界系统(ADS)靶件束窗形状设计,该文研究了一类含黏性力的最速降线问题。采用变分法进行分析,最终需数值求解一组非线性积分方程。针对Newton迭代法在高黏性系数情况下难以获得收敛解且无法获得近似解的缺陷,提出一种最优化求解思路。通过数值试验比较了4种启发式最优化算法的计算效率,并选择粒子群算法与Newton迭代法作进一步对比。结果表明:在高黏性系数情况下粒子群算法计算效率优于Newton迭代法,并且粒子群算法在该问题上近似线性收敛。用最速降线取代半椭圆的束窗形状后,流动分离更晚且流道滞止区更小,有利于提升换热效率。     

真空相移对束晕-混沌控制影响的一些研究

运用PIC多粒子模拟程序及延迟反馈控制器，通过数值模拟，研究了K—V分布束束晕-混沌控制中真空相移对束晕-混沌的影响，得到了控制效果最好的真空相移的范围，为强流加速器工程实现提供了有用的参考．     

反对称简易十二极场磁铁的设计

在散裂靶或废束站上形成均匀的、形状规则化的束斑分布,是散裂中子源、加速器驱动次临界系统(ADS)等高功率强流质子束应用研究课题中共性的关键技术.目前国际上一般认为采用反对称非线性高阶场磁铁进行打靶束斑均匀化变换是较为合适的.提出了一种新颖的非线性场磁铁——反对称垂直双向聚焦简易十二极场磁铁,该磁铁可以在交叉垂直的两个方向同时聚焦束晕粒子至束核内层或束团中心区域,可以较好地控制束晕;并配合其他反对称高阶场磁铁或阶梯场磁铁,可以在靶上较容易地得到基本均匀分布的近似圆斑束.同时给出了该种磁铁的结构装置及其制造方法.     

激光加速器装置CLAPA-II的研究进展

粒子加速器作为核物理科学中的核心仪器设备,是衡量综合国力的一项重要标志.常规粒子加速器已经有了百年的发展史,目前挑战主要集中在高流强、低发射度、更高加速梯度等方面.新加速机制的提出与研究是粒子加速器技术的新兴研究方向.由于激光与等离子体作用不存在击穿问题,产生的加速电场梯度远高于常规加速器,具有可以更加经济地实现高能粒子加速的潜力,一旦达到工程应用标准,将大幅降低加速器的建造应用门槛.但由于激光加速技术发展时间较短,在实际投入工程应用中仍面临很大挑战.为了实现激光加速技术从实验到实际应用的转化,在国家科技部和北京市的支持下,北京大学在怀柔科学城开展了激光加速器装置CLAPA-II的研发与建造.本文主要介绍了CLAPA-II装置的主要组成,以及关键核心技术相关研究进展.     

加速器高频扫描电压的传输与屏蔽

论述了在２．５ＭｅＶ质子静电加速器束流脉冲化装置中，提供尾部聚束所需的１２ＭＨｚ高频扫描电压系统的特点和问题，分析了产生高压传输和伴随干扰故障原因，提出了解决这些问题的方法，使之工作稳定，为加速器成功地实现了束流脉冲化．     

关于平面束一般方程的应用

在空间解析几何中，求解直线或平面的方程是一类重要题型，而应用平面束方程解题可达到事半功倍的作用。本文在介绍平面束一般方程的前提下，着重探讨了平面束方程在求解直线或平面方程中的应用。     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

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     

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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