蒙特卡罗方法用于研究堆的屏蔽计算

为解决研究堆的屏蔽计算问题 ,讨论了应用 MonteCarlo方法的 MCNP程序进行反应堆的屏蔽计算 ,引入了结合抽样技术的 MCNP分步计算的方法。该方法特别适用于计算物理模型比较大 ,屏蔽层比较厚 ,粒子的穿透距离比较长的问题。在这一类的问题中 ,单步计算根本无法计算出结果 ,利用分步计算和抽样技术则能在较短的时间内以较高的精度 (统计误差小于 10 % )得出结果。结合抽样技术的MCNP分步计算方法能够很好地解决深穿透问题     

风对建筑物体绕流的数值模拟

利用有限分析法数值模拟了风对建筑物体的绕流，对高雷诺数问题引进了一个经验公式较好地克服了实际中的困难，对方形、圆形及两头尖等各种形状物体绕流的计算结果表明数值方法在准确模拟各种形状建筑物体的绕流流场方面是成功的。     

基于Mask R-CNN的物体识别和定位

为了让机器人能识别物体类别、探测物体形状、判断物体距离,提出一种基于Mask R-CNN模型的双目视觉的物体识别和定位方法。该方法利用Mask R-CNN处理双目图像,对每张图像进行物体识别和形状分割,然后利用神经网络特征对双目图像中的相同目标进行匹配。以物体形状为依据,使用最近点搜索算法估计视差并计算距离。实验结果表明,该方法能够以准实时的速度进行物体的识别和定位,与传统的依赖计算全局视差图的方法相比,在速度和精度上都有提高。     

柔性物体实时可视化仿真

柔性物体形状的变化通常很复杂。如何实现柔性物体形状的实时更新是一个难点，以随风飘扬的旗子为例，给出了一种联合使用粒子系统和弹簧结构实时构造柔性物体的方法，为了提高场景渲染速度，又提出了一种快速计算顶点法线的简化算法，还介绍了柔性物体实时可视化仿真所涉及到的关键技术。     

深穿透屏蔽计算的离散坐标法

建立了堆芯几何和孔道几何边界源相耦合的离散坐标法。并用于计算反应堆孔道的深穿透屏蔽问题;推导出可用于堆芯几何屏蔽计算的半对称求积基,以及用于孔道几何屏蔽计算的偏向求积基。     

用于盲人视觉辅助的多目标快速识别并同步测距方法

提出一种以摄像头实现的可用于盲人视觉辅助的多运动目标快速识别并同步测距方法.该方法以深度学习多目标检测算法(single shot multibox detector,SSD)识别各类目标,并通过SSD输出的目标类别及检测框(bounding box)高度来提出测距模型,从而同步地获取多个目标的测量距离.本方法仅通过普通摄像头便能识别较多类物体且识别类别数量可拓展,能够将测距模块和障碍物识别模块同步执行,从而可对多个物体实时识别并同步测距.实验结果表明,本方法能有效地识别障碍物,具有良好的测距精度,为盲人视觉辅助的一种有效探索.     

基于射影对应的距离信息扩展原理及其应用

利用稀疏距离图象与灰度图象相结合，通过射影对应可使灰度图象特征有条件地获取距离信息，这称为基于射影对应的距离信息扩展原理。利用这些距离信息可计算物体表面平面图形的欧氏空间不变量并对景物中的物体产生假设。由于初始假设建立在可靠的基础上，并使用了带反馈的混合控制策略，使这种基于模型的物体识别定位技术具有实用的前景。本文讨论了整个方法的原理及其实施方案，并用实验验证了原理的正确性与有效性。     

用MCNP程序计算水平辐照孔道屏蔽

研究堆中水平辐照孔道用以从堆芯附近引出高能中子流。由于水平辐照孔道的几何形状比较复杂 ,采用两维输运计算模型将会引入较大的误差 ;同时 ,在计算过程中由于粒子穿行的距离比较长 ,所需的计算时间也是很大的。讨论了如何用 Monte Carlo方法的 MCNP程序进行水平孔道的屏蔽计算 ,引入了分段 -衔接计算方法 ,着重介绍了与 MC-NP的接口和表面源的设置问题。计算结果表明 ,分段 -衔接的 MCNP方法能够大大的改善 Monte Carlo方法的抽样 ,很好地解决水平辐照孔道的屏蔽计算问题     

材料表面硬度及形状的AFM分析方法

利用AFM测量软性材料如聚合体、生物物质时，AFM探针对被测软性材料表面施加一定的力而引起材料表面产生变形。通过测力-位移曲线，基于AFM测力-压痕曲线分析，探讨了减轻该影响并获得高精度软性材料表面形状测量结果的方法，进而计算材料表面微观杨氏弹性模量。该方法不仅可决定物体的表面弹塑性，获得高精度的表面形状测量结果，而且通过了解物体变形机理，进一步分析材料的微观特性。     

非线性因素对远场涡流探头特性的影响

采用线性和非线性有限元方法对带磁路和磁电组合屏蔽的远场涡流探头的信号——距离特性进行了计算机模拟,给出探头的信号——距离特性曲线。结果表明：铁磁材料的非线性因素导致激励电流密度与二次穿透区的位置直接相关联。     

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     

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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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has