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恒温下含硫酸钠盐粗颗粒土盐胀特征及过程研究 被引量:33
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作者 吴青柏 孙涛 +1 位作者 陶兆祥 李强 《冰川冻土》 CSCD 北大核心 2001年第3期238-243,共6页
通过恒温条件下粗颗粒土盐胀试验 ,对粗颗粒土盐胀特性进行了分析和讨论 ,试验结果表明 ,粗颗粒土不具有强烈盐胀特性 .然而 ,粗颗粒土体一旦形成硫酸钠盐聚集层后 ,遇外来水分 ,会发生突发的破坏性盐胀 ,造成建筑物的破坏 .
关键词 粗颗粒土 盐胀 恒温条件 硫酸钠盐 冰胀
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完美整数k-匹配和k-因子临界图
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作者 张燕红 张磊 任海珍 《数学杂志》 2024年第3期189-194,共6页
本文研究完美整数k-匹配和k-因子临界图的存在性.扩张常数表示图的连通强度,对于正则图,利用扩张常数给出了完美整数k-匹配存在的一个充分条件,这推广了Hamers等人和Cioabǎ等人的结果.此外,对于正则图,基于扩张常数还给出了k-因子临界... 本文研究完美整数k-匹配和k-因子临界图的存在性.扩张常数表示图的连通强度,对于正则图,利用扩张常数给出了完美整数k-匹配存在的一个充分条件,这推广了Hamers等人和Cioabǎ等人的结果.此外,对于正则图,基于扩张常数还给出了k-因子临界图存在的一个充分条件. 展开更多
关键词 完美整数k-匹配 k-因子临界图 连通性 扩张常数
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X射线衍射测量晶体材料的热膨胀 被引量:4
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作者 赵慧 王银海 《广东工业大学学报》 CAS 2011年第1期38-40,共3页
简述X射线衍射法测量材料热膨胀系数的基本原理,通过比较X射线衍射方法与传统热膨胀测量方法之间的不同,用测量实例说明了X射线衍射方法的使用范围.
关键词 X射线 热膨胀 晶格常数 衍射 布拉格公式
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Numerical analysis of acoustic band gaps in two-dimensional periodic materials 被引量:4
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作者 ZHAO Yan-cheng ZHAO Fang YUAN Li-bo 《Journal of Marine Science and Application》 2005年第4期65-69,共5页
Using the plane-wave expansion (PWE)method , the band gaps of the two-dimension phononic crystals composed of square, triangle and honeycomb arrays aluminum cylinders in the air are calculated numerically. The band st... Using the plane-wave expansion (PWE)method , the band gaps of the two-dimension phononic crystals composed of square, triangle and honeycomb arrays aluminum cylinders in the air are calculated numerically. The band structures of three lattices were compared and analyzed. It is concluded that the band-gap of honeycomb lattices is located at lower frequency fields, compared with square and triangle lattices. When the filling fraction is between 0.091 and 0.6046, the honeycomb lattices have larger band gaps and gain an advantage over square and triangle lattices. In addition, the gap map is introduced to illustrate the influences of filling fraction on the number, the relative width and the limit frequency of the band-gap. 展开更多
关键词 phononic crystal acoustic: band gap plane-wave expansion (PWE) method lattice constant
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膨胀水箱容积计算与安装接管问题 被引量:2
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作者 邹平华 孙宗宇 李祥立 《暖通空调》 北大核心 2004年第2期13-17,共5页
分析了常用计算公式存在的问题 ,给出了膨胀水箱容积计算公式。分析了水箱最低安装高度与系统形式和连接位置的关系、膨胀管和循环管与水箱及系统的连接位置对水循环的影响 ,指出对于高层建筑这两根管的连接间距和管径都可减小。指出了... 分析了常用计算公式存在的问题 ,给出了膨胀水箱容积计算公式。分析了水箱最低安装高度与系统形式和连接位置的关系、膨胀管和循环管与水箱及系统的连接位置对水循环的影响 ,指出对于高层建筑这两根管的连接间距和管径都可减小。指出了同时具备膨胀管和循环管的系统中定压点的位置。 展开更多
关键词 膨胀水箱 容积计算 安装 膨胀管 循环管 渗漏
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Standard Model Review and a New 5D Multi-Brane Proposition
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作者 Jami Hossain 《Journal of High Energy Physics, Gravitation and Cosmology》 2022年第1期195-227,共33页
Based on a comprehensive review of mainly the non-quantum aspects of the standard model of cosmology, the 5 dimensional models, and the analysis here, we propose a 5 dimensional model with expanding 4D multi-branes. A... Based on a comprehensive review of mainly the non-quantum aspects of the standard model of cosmology, the 5 dimensional models, and the analysis here, we propose a 5 dimensional model with expanding 4D multi-branes. A review of the standard model in the context of many new developments and discoveries in cosmology in the recent times, such as the accelerated expansion of the universe, Plank cosmic microwave measurements, dark energy survey, Hubble tension etc. tends to indicate that the standard model is essentially a patchwork of different theoretical models that have been pieced together in an attempt to explain different aspects of the astrophysical observations, which do not necessarily emanate from a full end-to-end understanding of a physical process. The purpose of each individual theoretical piece such as “inflation” is limited to providing an explanation to the problem area or a gap in our understanding. A number of new theories such as the five-dimensional universe, the bulk and brane, extended theories of gravity, and conformal cyclic cosmology offer alternate ways of addressing the existential aspects of the universe but these models too remain hypothetical with shortcomings and a lack of conclusive evidence. The model proposed by us, presents a way forward in addressing dark matter and dark energy as manifestations of the multiple underlying branes in the aftermath of the big-bang. In the process, we present a theorem of the dimensionality of the expanding universe, which necessitates the need for at least one more dimension in addition to the 4 dimensions of spacetime. While carrying out the review of the standard model, we present new analysis and facts that strengthen the case for the 5<sup>th</sup> dimension. According to the multi-brane hypothesis presented here, our observed universe could be one of the many branes, and it is more likely than not that in the <i>aftermath</i> of the big-bang that generated <i>our brane</i>, more branes were generated, which further points towards a much more 展开更多
关键词 BIG-BANG Dark Matter Dark Energy Cosmological constant Standard Model BRANE 5D Universe Accelerated expansion
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多晶粉末样品热膨胀的X射线衍射测量 被引量:2
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作者 赵淼 周严 +1 位作者 傅斌 郝延明 《天津师范大学学报(自然科学版)》 CAS 2005年第4期37-39,共3页
利用X射线衍射方法精确测量了2∶17型稀土化合物N d2A lFe15M n的晶胞参数及热膨胀系数并研究了其结构特征.结果表明,室温下,N d2A lFe15M n化合物具有单相的Th2Zn17型菱方结构(空间群为R 3m).对该化合物晶格常数的测量误差可以达到1-0... 利用X射线衍射方法精确测量了2∶17型稀土化合物N d2A lFe15M n的晶胞参数及热膨胀系数并研究了其结构特征.结果表明,室温下,N d2A lFe15M n化合物具有单相的Th2Zn17型菱方结构(空间群为R 3m).对该化合物晶格常数的测量误差可以达到1-0 4,基本上可满足对一般位移型相变测量要求的精度. 展开更多
关键词 X射线衍射 热膨胀 晶胞参数
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基于晶格动力学的硅单晶热学性质研究(II)——晶格非和谐势能和格律纳森参数 被引量:2
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作者 贺业鹏 黄建平 《应用物理》 CAS 2020年第11期467-475,共9页
为用晶格动力学方法研究硅单晶的热膨胀性质,必须首先计算作为微扰哈密顿的硅单晶晶格的三阶非和谐势能,而三阶非和谐势能的计算又可以建立在已知不同晶格常数所对应的晶格和谐势能的基础上,因此本文运用他人计算得到的最近邻和次近邻... 为用晶格动力学方法研究硅单晶的热膨胀性质,必须首先计算作为微扰哈密顿的硅单晶晶格的三阶非和谐势能,而三阶非和谐势能的计算又可以建立在已知不同晶格常数所对应的晶格和谐势能的基础上,因此本文运用他人计算得到的最近邻和次近邻原子间的相互作用力常数,推导了的硅单晶的晶格和谐势能公式,并在此基础上根据不同晶格常数下的晶格和谐势能推导了三阶非和谐势能公式,为后续硅单晶的热膨胀系数计算公式的推导做了必要准备。最后还运用本文提出的三阶非和谐势能模型,计算了不同温度下硅单晶的格律纳森参数,发现其与他人的实验结果吻合,从而验证了本文所提出的三阶非和谐势能模型的正确性。 展开更多
关键词 硅单晶 热膨胀 晶格动力学 力常数 非和谐势能 格律纳森参数
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无穷求和与渐近展开 被引量:2
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作者 邱为钢 《大学物理》 北大核心 2015年第10期23-24,34,共3页
利用欧拉麦克劳林求和公式,得到了圆链上马德隆常数的渐近展开和解析表达式.
关键词 欧拉麦克劳林公式 渐近展开 圆链 马德隆常数
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低温氢膨胀叶轮设计及其变工况性能预测
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作者 滕越 赵骞 +3 位作者 王缔 陈世雄 张启勇 陈国宏 《低温与超导》 CAS 北大核心 2022年第10期100-106,共7页
氢透平是氢液化循环系统的重要部件之一,其三元叶轮的设计与分析是氢透平设计的主要内容。本文针对5吨/天氢液化循环中的一台透平,设计了向心式氢膨胀叶轮及喷嘴,采用数值仿真对其进行了流动特性分析,进一步预测了透平在定转速和定特性... 氢透平是氢液化循环系统的重要部件之一,其三元叶轮的设计与分析是氢透平设计的主要内容。本文针对5吨/天氢液化循环中的一台透平,设计了向心式氢膨胀叶轮及喷嘴,采用数值仿真对其进行了流动特性分析,进一步预测了透平在定转速和定特性比调节方式下的变工况运行性能。结果表明,流道内流体整体上处于亚音速流动状态,流动损失主要发生在喷嘴出口、叶片压力面进口处、叶片吸力面中部及叶顶间隙内;喷嘴中压降、温降均大于叶轮;当流量在0.4~0.6 kg/s的区间内变化时,功率与质量流量呈现了拟线性的增长关系;变工况运行时,定特性比调节比定转速调节具有更高的等熵效率,且低负荷工况下这种优势更为明显。 展开更多
关键词 氢透平 膨胀叶轮 定转速 定特性比 变工况性能
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An Algorithm to Determine RBFNN’s Center Based on the Improved Density Method
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作者 Mingwen Zheng Yanping Zhang 《Open Journal of Applied Sciences》 2014年第1期1-5,共5页
It takes more time and is easier to fall into the local minimum value when using the traditional full-supervised learning algorithm to train RBFNN. Therefore, the paper proposes one algorithm to determine the RBFNN’s... It takes more time and is easier to fall into the local minimum value when using the traditional full-supervised learning algorithm to train RBFNN. Therefore, the paper proposes one algorithm to determine the RBFNN’s data center based on the improvement density method. First it uses the improved density method to select RBFNN’s data center, and calculates the expansion constant of each center, then only trains the network weight with the gradient descent method. To compare this method with full-supervised gradient descent method, the time not only has obvious reduction (including to choose data center’s time by density method), but also obtains better classification results when using the data set in UCI to carry on the test to the network. 展开更多
关键词 RADIAL BASIS Function Neural Network Data CENTER expansion constant Density Method Full-Supervised ALGORITHM
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Gravity vs. Dark Energy, about the Expansion of the Universe
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作者 Olivier Serret 《Journal of Modern Physics》 2018年第1期84-97,共14页
Dark energy is argued by the accelerating expansion of the Universe but has not been directly measured. In this article, some uncertainties are pointed out, first one being the determination of the Hubble constant. An... Dark energy is argued by the accelerating expansion of the Universe but has not been directly measured. In this article, some uncertainties are pointed out, first one being the determination of the Hubble constant. And the main parameters (magnitude, distance, redshift, velocity) are checked. Distinguishing the instantaneous velocity from the average velocity, it is then concluded from the same data that the expansion would not be accelerating, and that the Gravity would slightly slow down the motion of explosion. Moreover, at the end of the paper, it is proposed a neo-Newtonian approach to get the computed values in a closer agreement with the observed values;this Neo-Newtonian Mechanics is in coherence with the Quantum Mechanics. 展开更多
关键词 Acceleration expansion Inflation Universe COSMOS Magnitude REDSHIFT HUBBLE constant Uncertainties of Measure Dark Energy GRAVITATION Relativity Neo-Newtonian Mechanics
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Thermodynamics in the Evolution of the Dark Universe
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作者 Carlos A. Melendres 《Journal of Modern Physics》 2021年第11期1527-1544,共18页
We present a model of the universe based on the theory that space consists of energy quanta. We use the thermodynamics of an ideal gas to elucidate the composition, accelerated expansion, and the nature of dark energy... We present a model of the universe based on the theory that space consists of energy quanta. We use the thermodynamics of an ideal gas to elucidate the composition, accelerated expansion, and the nature of dark energy and dark matter without an Inflation stage. From wave-particle duality, the space quanta can be treated as an ideal gas. The universe started from an atomic size volume at very high temperature and pressure. Upon expansion and cooling, phase transitions occurred to form fundamental particles, and matter. These nucleate and grew into stars, galaxies, and clusters due to gravity. From cooling data, a thermodynamic phase diagram of cosmic composition was constructed which yielded a correlation between dark energy and the energy of space. Using Friedmann’s equations, our model fits well the Williamson Microwave Anisotropy Platform (WMAP) data on cosmic composition with an equation of state parameter, <em>w</em> = -0.7. The dominance of dark energy started at 7.25 × 10<sup>9</sup> years, in good agreement with Baryon Oscillation Spectroscopic Survey (BOSS) measurements. The expansion of space can be attributed to a scalar space field. Dark Matter is identified as a plasma form of matter similar to that which existed before recombination and during the reionization epoch. The expansion of the universe was adiabatic and decelerating during the first 7 billion years after the Big Bang;it accelerated thereafter. A negative pressure for Dark Energy is required to sustain it;this is consistent with the theory of General Relativity and energy conservation. We propose a mechanism for the acceleration as due to the consolidation of matter to form Black Holes and other massive compact objects. The resulting reduction in gravitational potential energy feeds back energy for the acceleration. It is not due to a repulsive form of gravity. Our Quantum Space model fits well the observed behavior of the universe and resolves the outstanding questions in Inflationary Big Bang Theory. 展开更多
关键词 THERMODYNAMICS Quantum Space Model Dark Universe Composition and expansion Phase Diagram Spaceons Dark Energy Dark Matter Cosmological constant INFLATION
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An Extended Version of Hubble’s Law
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作者 G. Alagar Ramanujam Keith Fitzcharles S. Muralidharan 《Journal of Modern Physics》 2017年第7期1067-1071,共5页
Friedmann-like cosmological equations were derived by us in a recent paper by using axioms proposed by us for the so called empty Space. By using one of our cosmological equations we have derived in this paper a relat... Friedmann-like cosmological equations were derived by us in a recent paper by using axioms proposed by us for the so called empty Space. By using one of our cosmological equations we have derived in this paper a relation between the expansion velocity of the universe and the radius of the universe. This relation may be considered as an extended version of Hubbles’ Law. According to our relation derived here, the Hubble factor H goes on decreasing as the radius increases. 展开更多
关键词 COSMOLOGICAL EQUATIONS expansion of the UNIVERSE Hubble’s constant DARK Energy
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Revised Newtonian Formula of Gravity and Equation of Cosmology in Flat Space-Time Transformed from Schwarzschild Solution
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作者 Xiaochun Mei Ping Yu 《International Journal of Astronomy and Astrophysics》 2012年第1期6-18,共13页
By transforming the geodesic equation of the Schwarzschild solution of the Einstein’s equation of gravity field to flat space-time for description, the revised Newtonian formula of gravity is obtained. The formula ca... By transforming the geodesic equation of the Schwarzschild solution of the Einstein’s equation of gravity field to flat space-time for description, the revised Newtonian formula of gravity is obtained. The formula can also describe the motion of object with mass in gravity field such as the perihelion precession of the Mercury. The space-time singularity in the Einstein’s theory of gravity becomes the original point r = 0 in the Newtonian formula of gravity. The singularity problem of gravity in curved space-time is eliminated thoroughly. When the formula is used to describe the expansive universe, the revised Friedmann equation of cosmology is obtained. Based on it, the high red-shift of Ia supernova can be explained well. We do not need the hypotheses of the universe accelerating expansion and dark energy again. It is also unnecessary for us to assume that non-baryon dark material is 5 - 6 times more than normal baryon material in the universe if they really exist. The problem of the universal age can also be solved well. The theory of gravity returns to the traditional form of dynamic description and becomes normal one. The revised equation can be taken as the foundation of more rational cosmology. 展开更多
关键词 General Relativity SCHWARZSCHILD Metric COSMOLOGY Friedmann Equation NEWTONIAN GRAVITY Supernova Hubble constant DARK Material DARK Energy UNIVERSE Accelerating expansion UNIVERSE Age
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Accelerating Expansion in a Closed Universe
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作者 Martin Tamm 《Journal of Modern Physics》 2015年第3期239-251,共13页
In this paper, I suggest a possible explanation for the accelerating expansion of the universe. This model does not require any dark energy or quintessence. Rather, the idea is to suggest a different view on the origi... In this paper, I suggest a possible explanation for the accelerating expansion of the universe. This model does not require any dark energy or quintessence. Rather, the idea is to suggest a different view on the origin of general relativity. Since it is very difficult to say something in general, I will mainly restrict myself to the case of very low curvature. The question about the underlying reasons for the acceleration is also closely related to the question whether the universe is a finite or infinite. It is part of the purpose of this paper to argue that a phase of accelerating expansion may be very well compatible with the idea of a closed universe. 展开更多
关键词 DARK Energy Theory QUINTESSENCE Modified Gravity General RELATIVITY Accelerating expansion COSMOLOGICAL constant
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关于变参数离散动力系统的生成子问题 被引量:1
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作者 宋晓倩 《高师理科学刊》 2009年第1期22-24,共3页
引进了变参数离散动力系统的生成子、弱生成子的概念,证明了变参数离散动力系统有生成子当且仅当它有弱生成子,并且研究了变参数离散动力系统的生成子的其它性质,从而扩展了变参数离散动力系统的研究范围.
关键词 离散动力系统 生成子 弱生成子 开覆盖 扩张常数
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玻璃态聚合物的Grüneisen常数计算 被引量:1
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作者 邹义龙 周永祥 《华东化工学院学报》 CSCD 1991年第3期297-301,共5页
本文用似谐振子模型得出了聚合物非线性振动的Gruneisen常数计算式,并用聚甲基丙烯酸甲酯的实验值加以比较,所得结果与文献报道一致。
关键词 玻璃态 聚合物 膨胀系数 计算
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Thermal Expansion of Solids
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作者 Zdzislaw Pluta Tadeusz Hryniewicz 《Journal of Modern Physics》 2012年第8期793-802,共10页
The work covers a novel approach to the description of the phenomenon of thermal expansion of solids. The reason for undertaking the scientific quest is presented to follow with the analysis of existing knowledge on t... The work covers a novel approach to the description of the phenomenon of thermal expansion of solids. The reason for undertaking the scientific quest is presented to follow with the analysis of existing knowledge on the characteristics of phenomenon of thermal expansion of bodies being in the state of aggregation. A critical approach to the existing law of the linear thermal expansion is given. The paper presents an adequate approach to this considered phenomenon. The description provides parametric and functional characteristics of this phenomenon. The relationships of the coefficients of linear expansion on temperature for particular interstate zones, as well as the initial coefficients related to these zones, are presented. In the summary a synthesis of all actions and considerations with the directions to the adequate knowledge with advantage on the subjected phenomenon has been performed. It regards also to the latest thermal characteristics of solids, referred to the phase transformations. All they are realized by dilatometric studies together with determination of curves of thermal expansions of solids. 展开更多
关键词 Thermal expansion Coefficient of Linear Thermal expansion Relative Length Increment Temperature constant Temperature Potential Field Deformation Potential Field Nominal Potential Field Deformation-Temperature Space
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坝后空间明弯压力钢管自承方式的试验研究
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作者 邓训 马善定 +1 位作者 王文安 陈黎明 《武汉水利电力学院学报》 CSCD 1990年第6期17-24,共8页
本文通过坝后空间明弯压力钢管的整体模型试验研究,验证了采用自承方式(不设置三向伸缩节和镇墩)的压力钢管工程应用的可行性,给出了在诸多工况因素偶和作用下,试验模型测点处的应力及相当应力。其成果与SAP—V电算结果进行了比较。
关键词 压力管 空间 自承方式 试验
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