燃气轮机装置热力参数优选下的回热器结构参数优化

引入无量纲熵产数Ns表示燃气轮机装置热力性能的完善程度,对其进行热力性能熵产分析,综合考虑压力比π、温度比τ和回热度σ对熵产数Ns的影响,进行了熵产数Ns尽可能小的热力性能参数优选.以板翅式回热器为例,采用穷举法优化计算方法,期望传热面密度达到最优.经热力参数与结构参数优化,达到提高燃气轮机循环效率、减少耗能的目的.     

时间延迟和关联噪声对基因转录调节系统统计性质的影响

研究延迟时间τ和交叉关联噪声对基因转录调节系统关联函数C(s)和弛豫时间TC的影响.在小延迟近似下,利用微扰理论,得到了系统的定态概率分布函数Pst(x).基于Pst(x),通过Stratonovich解耦近似框架导出了C(s)和TC的近似表达式.数值计算结果表明,TC随乘性噪声强度D的变化曲线呈一单峰结构,τ和噪声间正关联时的关联强度λ的增大均使TC增大,而噪声间负关联时|λ|和加性噪声强度α的增大则使TC减小;系统态变量x(蛋白质浓度)的C(s)随时间s呈指数规律衰减,τ对C(s)的影响显示一个临界行为,即存在一个临界值τC,当ττC时,τ的增大使C(s)增大,而ττC时,使C(s)减小.λ0时,λ增大使C(s)增大,而λ0时,使其减小.D对C(s)的影响也显示一个临界行为,即D较小和较大时D的增大对C(s)的影响相反,然而,α的增大只会使C(s)值减小.     

洱海泥炭质土滞回曲线形态特征的定量研究

以重塑泥炭质土为研究对象,利用全球数字系统(global digital systems,GDS)动三轴仪对土体进行循环加载试验,分析一系列围压、固结比(Kc)、频率下土体滞回曲线演化规律,采用滞回曲线长轴斜率(k)、中心偏移量(d)、动应变幅值(εm)和包围的面积(S)对洱海高原湖相泥炭质土滞回曲线形态特征进行定量描述.试验结果表明:泥炭质土滞回曲线较为封闭,整体呈长梭形,在相同动应力幅值下,εm随围压、固结比、频率增大而减小,且减小速度逐渐降低;k随动应力幅值(σm)增大呈对数关系衰减,随围压、固结比、频率增大而增大,加载前期对频率变化表现不敏感;d和S随σm增大呈两阶段增大,加载前期增大平缓,后以指数关系快速增大;d和S随围压和频率增大而减小,且对频率变化表现更敏感;非等压固结(Kc≠1.0)条件下的d比等压固结(Kc=1.0)条件下更大,且S即土体完成一个荷载循环消耗能量更小.     

石灰土填料动力特性试验研究

在大量动三轴试验的基础上,深入研究了石灰土填料的动力特性.试验结果表明:动应变εd是影响土样动弹模量及阻尼比的最主要因素,随着动应变水平的提高,动弹模量Ed成倍减小而阻尼比λ成倍增大.随着掺灰比的增大,石灰土的动弹模量和阻尼比相应增大.动弹模量随围压σ3增减而增减,阻尼比λ随围压σ3的增加而减小.最大动弹模量Edmax与围压σ3呈指数递增关系;最大阻尼比λmax在7%～40%之间,与围压σ3呈指数递减关系,并建立了相应的经验公式.图10,表4,参14.     

熵变和周期固定时二热源制冷循环的最优化

本文讨论受热阻影响的二热源制冷循环的最优化问题。对循环周期τ和工质在膨胀过程中的熵变σ给定的情况下,导得了各种性能界限。这些性能界限比起可逆界限更有现实意义,指明了不可逆性和约束条件对循环性能的具体影响。此外,还指出,循环时间的最优分配是放热的时间比吸热的时间长。     

两类噪声对光学双稳系统性质的影响

利用斯特拉托诺维奇近似得到关联函数C(s)表达式的基础上,分析高斯噪声和非高斯噪声对系统性质的影响。结果表明:①C(s)随非高斯噪声参数Q的增大出现峰值,表明随Q的增大,输出x的涨落的衰减先慢后快;②高斯噪声强度D较小时,C(s)随D的增大而增大,但D超过一定数值时,C(s)不再随D的增大而变化;③C(s)随自关联时间τ的增大出现极大值,且关联强度λ越小,该极大值越明显;④λ取值较小时,C(s)随非高斯噪声参数q的增大而增大,λ取值较大时,C(s)随q的增大而减小,表明由于λ的取值不同,q既可以延缓也可以加快x涨落的消退。     

熵变和周期固定时放热是定压过程的二热源制冷循环的最优化

本文讨论了受热阻影响的二热源的内循环的放热过程是定压过程的制冷循环的最优化问题。对循环周期τ和工质在膨胀过程中的熵变σ给定情况下,导得了等压过程等效的等温过程和各种性能的界限。这些性能界限比起可逆界限及内循环定可逆卡诺循环的界限更有实际意义。     

部分相干厄米高斯光束的湍流距离

根据广义惠更斯-菲涅耳原理和积分变换技术,推导出了部分相干厄米高斯(H-G)光束传输于大气湍流的湍流距离表达式,并定量地研究了湍流对部分相干H-G光束扩展的影响.研究表明,湍流距离ZT与折射率结构常数C2n、光束阶数m、相干长度σ0及波长λ有关,且ZT随C2n、σ0的增大而减小,随m的增大而增大.即随着C2n、σo的增大,m的减小,湍流对部分相干H-G光束扩展的影响将增大.因此,选择合理的光束参数可减小湍流对部分相干H-G光束扩展的影响.     

黄土邓肯-张模型有限元计算参数的试验

为配合有限元计算分析的需要，从工地现场取样，进行了黄土的室内三轴试验，并对试验结果进行了分析，得到了邓肯-张非线性模型有限元计算的8个参数。黄土的有限元参数随着试样的压实度和试验时围压的不同而变化。在含水量保持不变的情况下，邓肯-张E～μ模型的8个参数中，参数K、n、Rf、C、φ、G均随压实度的提高而增大；F、D随K的变化规律不明显。在含水量和压实度保持不变的情况下进行三轴试验，土样的（σ1-σ3）f、（σ1-σ3）ult、Ei、Rf均随σ3的增大而增大，μi随σ3的增大而减小，D随σ3变化的规律不明显。     

有限时间的蒸气压缩制冷循环热力参数优化

基于有限时间热力学的理论,引入无因次熵产率,提出转换温度的概念,以无因次熵产率和无因次制冷率表示实际制冷循环热力性能完善程度和制冷能力大小,分析了实际蒸气压缩制冷循环反映温差的各无量纲量和性能参数比等对循环性能的影响及相互关系.研究结果表明,在不增加不可逆传热温差的情况下,环境温度不变,可采用提高低温热源温差比、降低高低温热源比和性能参数比的方法来提高制冷率.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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