水下飞出“战斧”——SSGN超级火力攻击潜艇

SSGN超级火力攻击潜艇,是美国即将开发的新潜艇。据《美国新闻与世界报道》周刊报道,美国方面围绕该潜艇的开发与否进行过一场辩论。争论的焦点是,反对者认为开发该潜艇的费用太高。据估计,若将一艘即将退役、运载远程核导弹的“轰炸潜艇”加以改造,至少需要5亿美元。另一派赞成者的理由则是,该潜艇在发射“战斧”导弹的基础上,可以形成一套隐形武器系统。这套系统可以“在一个星期内摧毁一个国家。”     

高速圆射流中典型非球形颗粒的扩散特性

低氧稀释(moderate and intense low-oxygen dilution,MILD)燃烧具有传热均匀、 NO_x污染物排放低的特点。新一代MILD煤粉燃烧技术主要通过高速射流引起强烈的湍流混合来实现。其中,煤颗粒在高速射流中的扩散行为非常关键。目前对球形颗粒在气固射流中扩散行为的研究已非常深入,然而化石燃料属于典型的非球形颗粒,其在射流中的扩散行为与球形颗粒具有一定的差异,该类非球形颗粒在高速射流下的扩散特性值得进一步研究。为此,该文采用玻璃珠、玻璃渣和煤粉等颗粒开展了宽Re范围下的高速两相圆射流实验,通过激光Doppler相位分析技术(phase-Doppler anemometry,PDA)获取并分析了颗粒的质量浓度、速度及湍动能分布随球形度、粒径以及射流速度的变化规律。结果表明:非球形颗粒在射流中的质量浓度、速度、湍动能分布与粒径较小的球形颗粒具有一定相似性,但其扩散行为不能仅通过Stokes数进行定量表征,除曳力之外,升力对非球形颗粒扩散也具有一定影响;与球形颗粒相比,非球形颗粒的扩散更为显著,其主要原因是其径向湍动能显著增强所致;射流速度的增加促进了颗粒的剪切层集聚和径向扩散,对非球形颗粒的促进作用更强。     

高密度弗劳德数热浮力射流特性实验

为研究潜艇热尾流的浮升规律与水面特征,将潜艇冷却水排放形成的热尾流等效简化为水平圆形热浮力射流,在高弗劳德数条件下,采用给定的射流出口速度和不同的射流管径与射流温差组合条件进行系列实验.结果表明:当管径相同时,热浮力射流到达水面时的水平运动距离随密度弗劳德数增加而增大;同时,采用特征参数进行无量纲化处理后,各工况下的浮升轨迹中心线归一于同一曲线;热射流浮升引起的水面温升峰值出现在中心轨迹线与水面的交界位置,射流开始后温升峰值先随时间增大,达到最大值后趋于稳定;通过拟合分析,得到了最小稀释度与密度弗劳德数及射流淹没度的函数关系.     

潜艇电力推进系统及其电源变换技术

针对探测潜艇综合全电力系统的供电电压低,无法使推进电机工作在最佳工况的问题,设计一套为主推进电机供电的DC-DC变换器,并配置一套主推进变频器.分析探测潜艇的电力系统和主推进变频器的工作原理,给出DC-DC变换器主电路的元件参数和控制电路的设计过程.实验结果表明,在额定负载时,主推进电动机运转稳定,变换器效率较高.     

掺气坎射流空腔积水计算

采用力学分析的方法,从理论上建立了掺气坎射流空腔积水的方程式,结合考虑空腔内负压及运动液体所受离心惯性力影响的射流水舌下缘液体质点运动轨迹的微分方程,可以计算掺气坎射流空腔内的积水深度和净空腔长度,计算结果与实验值趋势一致,吻合良好,可供设计单位参考．与此同时,从理论上对掺气坎射流空腔积水的机理进行了初步探讨,对计算误差的产生原因进行了详细分析并提出了提高计算精度的下一步研究思路．     

基于目标流量拟合的微型燃烧室流量分配设计方法

通过改变射流孔的布置调节燃烧室的流量分配是提高燃烧室燃烧性能的重要设计方法.为了降低燃烧室流量分配设计时总结各射流孔流量规律所需的仿真计算成本,根据在研的微型燃烧室几何模型和初次仿真结果建立了燃烧室流量-压力数学模型,提出用计算替代大量仿真获取射流孔当地流量规律的流量放缩拟合法,并进一步根据燃烧室流量-压力数学模型和射流孔当地流量规律设计得到满足目标流量分配要求的射流孔布置方案.结果表明:在初始算例流量分配误差较大的情况下,仅需两次设计计算流程即可以将燃烧室各排射流孔流量与目标流量的相对误差减小到5%以下.与传统方法相比,该方法总结射流孔当地流量规律所需的数据量小,且考虑了燃烧室整体几何因素对横向射流的影响.     

体积力在潜艇自航因子预报中的应用

借助于CFD软件,在螺旋桨参数未知的情况下,用均匀分布的体积力模拟螺旋桨力场,对潜艇自航因子进行了预报,并与潜艇带桨自航试验数值模拟的结果进行了对比.发现:若体积力参数仅考虑螺旋桨轴向力,则潜艇阻力的计算误差可达7％,在引入螺旋桨旋转的影响后,这一误差值可降低至2％以内,同时,推力减额分数和平均轴向伴流分数的计算误差可控制在5％以内,而潜艇快速性的预报误差可控制在2％以内.用均布体积力模拟螺旋桨力场的方法,能够有效地预报潜艇伴流和推力减额分数,为螺旋桨的设计提供可靠的输入参数,也可以用于潜艇线型优化设计和快速性预报.     

荷兰推出迷你微型潜艇可载4人海底探险

荷兰沃克斯潜艇公司最近推出的4人座微型潜艇，外形与描写未来太空时代高科技生活的美国老动画片《杰森一家》中的飞船很相像，但是这种微型潜水艇的设计目的是潜入大海深处。     

几种碰撞时间计算公式的推导

本文是继《碰撞时间的定量计算》一文之后,再对斜碰撞、定点碰撞和非球形物体碰撞时间的计算问题作出讨论,并给出相应的时间计算公式。     

垂直温差射流轴心速度的计算

在通风工程设计中，通过风口空气射流轴心速度的计算是设计的重要依据，目前，计算空气射流有效射流段内相应轴心速度的计算式是等温射流的计算式，实际上通风口空气射流与周围空气的温度是不相等的，有时温差还比较大。     

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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