被动轮式推进器设计

针对连续管水平井钻进过程中存在的屈曲锁死、钻压不足等问题,设计一种基于钻柱侧向弹性的增强动力轮式推进器,可获得较高的轴向推拉力。应用钻柱纵横弯曲理论和齿轮-钻屑的几何关系,分别建立包含轮式推进器的底部钻具组合力学模型和蜗轮蜗杆卡阻力学模型,利用模型分析轮式推进器的工作特性。结果表明仅靠钻柱自重产生的推拉力有限,利用偏心垫块与推进器串联组合所产生的钻柱侧向弹性可大幅提高轴向推拉力;偏心垫块-推进器组合的轴向推拉力随两者间距的减小而增大、随偏心距增大而增大,较自重式推进器提高10倍。最大被卡钻屑尺寸随齿轮模数和齿数的增大而增大;卡阻力与钻屑和齿轮材料的强度比正相关。     

螺旋推进器与机器的配合

机器与推进器裝在船上成为一个复杂的联动机,由机器供給能量,將推进器軸旋转,推进器把此旋转的动能转化为推力动能,克服船的阻力使船前进,所以机器与推进器的能量轉換是相互牵制、相互有关的,这与在試驗台上的机器或推进器單独进行試驗的情况不同。造船設計人員及輪机工作人員經常对机器与推进器的相互关系感到苦惱,因为在实际工作中,时常遇到风浪、輕載、倒車等各种負荷情况;結果不是馬力不足,就是转数加大,造成机器过負荷。一般我們虽也略知其控制办法,但对其确切的規律则知道甚少,这是由于其中的变数太多;当外界負荷不同时,在机器方面就要牵涉到馬力N,轉速n,轉矩M,工質参数ε,燃油消耗量q,机器效率ηM等的变化;在推进器方面則要牽涉到推进器馬力N_R,船速v,轉速n,轉矩M,推进器效率η等的变化。并且这許多变数中又是相互关联、相互平衡的,所以螺旋推进器与机器的配合与工作是一个很複杂的問題。現分下面几方面来进行探討: 一、机器与螺旋推进器的性能二、螺旋槳与机器在額定情况下的配合三、机器部分負荷特性曲线与外界負荷特性曲线四、部分螺旋槳的工作情况五、轉速与船速的关系六、开車、加减速、回轉、卡住、飞車与倒車的工作情况七、結束語 八、参考文献     

拖式与推式吊舱推进器水动力性能数值仿真及对比

为研究吊舱推进器在直航和回转工况下的推进性能,通过RANS方法结合标准k-ε湍流模型对拖式与推式吊舱推进器在不同工况下的水动力性能进行对比分析.分别计算拖式与推式吊舱推进器直航与回转工况下的推力系数与转矩系数,并与试验结果进行对比以验证数值计算的准确性.直航工况推进特性曲线、回转工况的推力系数与转矩系数曲线对比结果表明,数值计算可以准确预报吊舱推进器的水动力性能.根据该模型计算了斜流工况时两种推进器的推力、转矩系数以及轴向力和侧向力系数随角度的变化规律.结果表明,本文提出的水动力模型可以准确预报不同工况下吊舱推进器的水动力性能.     

螺旋推进器叶型数值模拟研究

全地形两栖螺旋管道机器人采用螺旋式推进结构，适用于在水面、淤泥、沼泽等多种复杂环境工作，被广泛应用于城市排水管道系统中。为探究螺旋推进器叶型在地面与敞水中的最佳动力性能参数，通过公式计算出螺旋推进器在地面运动最佳螺旋升角范围，并对该范围内不同叶型螺旋推进器进行敞水数值模拟，分析了螺旋推进器不同叶型在敞水中的推力以及速度特性。结果表明：螺旋推进器叶型在地面最佳角度范围内，随着叶片螺旋升角逐渐增大，螺旋推进器获得的推力逐渐变大，叶片螺旋升角在29°～31°范围内螺旋推进器速度存在极大值，此区间内螺旋推进器对周围流体环境影响最大。研究结果对全地形两栖螺旋管道机器人叶型设计具有一定的参考价值。     

一个组合数学问题

讨论展开式（η＿１＋ｂη＿０）（η＿２＋ｂη＿０＋ｂη＿０）…（η＿ｎ＋ｂη＿（ｎ－１）…＋ｂ￣ｎη＿０）．引入个迅速求得Ａｆ（ｎ）的计算规则，以及系数的计算公式，这公式是牛顿二项式展开系数公式的推广。     

全内腔式632.8nm氦氖激光管工作寿命的快速测试公式

通过对三厂家全内腔式６３２．８ｎｍ氦氖激光管寿命试验数据的分析，得到其正常工作寿命的快速测试公式：η０＝４．６０ηｉ，η０＝４．８６ηｉ，这表明，在２０ｍＡ电流下短时间测得的特征寿命ηｉ能以快近５倍的时间快速推知氦氖激光管额定工作电流５ｍＡ下的工作寿命η０。推得的结果与实际符合很好。     

Ni基与Ni-P基含MoS_2复会电刷镀层的减摩特性

在“球－盘”试验机上对Ｎｉ／ＭｏＳ２与 Ｎｉ－Ｐ／ＭｏＳ２两种复合镀层的摩擦磨损性能进行全面的测试与比较，并对其作用机理进行了分析。试验结果表明，两种复合镀层在油润滑条件下的摩擦系数，一般均可达到 ０．０５～０．０６的水平，而 Ｎｉ－Ｐ／ＭｏＳ２的承载能力或磨损寿命要比 Ｎｉ／ＭｏＳ２提高 ４～６倍以上。     

烯酮光化二聚反应中非绝热跃迁的经典轨迹方法研究

用经典轨迹方法，在π－ＣＩ势能面水平上计算了烯酮光化二聚的Ｈｕｃｋｅｌ途径和Ｍｏｂｉｕｓ途径的非绝热耦合项。根据非绝热跃迁几率的Ｌａｎｄａｕ－Ｚｅｎｅｒ公式，定义η＝ｌｎＰ（Ｈ）／ｌｎＰ（Ｍ）并用以讨论光化学反应的立体选择性。计算结果表明，光化学反应受两态Ｓ１和Ｓ０接近交叉处的能量间隙ΔＥｃ的控制，ΔＥｃ越小非绝热跃迁几率越大。     

POD推进器推进性能预报理论研究

基于已有的螺旋桨数字计算方法,建立了POD推进器定常水动力性能的理论计算方法,并进行了实例计算,其结果与试验相比具有较高的精度．应用升力面理论涡格法和面元法探索了POD推进器的定常水动力性能预报理论方法．     

应用扩展的Monod模型关联醋酸菌比生长速率

应用扩展的Ｍｏｎｏｄ模型关联了醋酸菌ＩＡＭ１８０２和Ｍ２３的比生长速率，ＩＡＭ１８０２的比生长速率关联式为μ＝０．４８７（１－ＣＰ／２３．８）＾０．２４８ＣＡ／ＣＭ＋ＣＡ；Ｍ２３的关联式为μ＝０．５６８（１－ＣＰ／６１．０）＾０．３０６ＣＡ／ＣＭ＋ＣＡ除临界生长抑制剂浓度附近外，模型良好地表达了两种醋力的比生长速率。     

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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