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Simulation of small particle penetration in a random medium 随机介质中小颗粒穿透的模拟
Pub Date : 1990-12-01 DOI: 10.1051/JPHYS:0199000510230267300
P. Meakin, R. Jullien
Random packings of identical spheres of unit diameter were built according to a procedure in which spheres are released one after another along randomly positionned vertical trajectories and then follow the path of steepest descent on the others until they reach a stable position under gravity. Once a packing has been built, smaller spheres, of diameter d does not diverge but saturates to c 11 and the histogram N reaches an exponential shape whose large ΔZ tail is well fitted by N α exp(−0.103 ΔZ). It is shown that such behavior is due to a non zero proportion of equilateral triangles of tangent spheres in the random packing
在重力作用下,球体沿着随机定位的垂直轨迹一个接一个地释放,然后沿着其他球体上最陡的下降路径,直到它们达到稳定的位置,按照这样的程序,构建了单位直径的相同球体的随机填料。一旦建立了一个填料,直径为d的较小的球体不会发散,而是饱和到c11,直方图N达到指数形状,其大的ΔZ尾部很好地拟合了N α exp(- 0.103 ΔZ)。结果表明,这种现象是由于随机填充中切线球等边三角形的比例不为零造成的
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引用次数: 13
Fluctuations in the flat and collapsed phases of polymerized membranes 聚合膜的平相和塌相的波动
Pub Date : 1990-12-01 DOI: 10.1051/JPHYS:0199000510230265300
F. F. Abraham, D. Nelson
Fluctuations in polymerized membranes are explored via extensive molecular dynamics simulations of simplified «tethered surface» models. The entropic rigidity associated with repulsive second-nearest-neighbor interactions leads to a flattening of «phantom surfaces». An attractive interaction in the presence of distant self-avoidance leads to a collapsed membrane with fractal dimension three at sufficiently low temperatures. When the attractive interaction is turned off, the surface returns to the flat phase found in earlier simulations. A study of density profiles and hexatic internal order allows a simple physical interpretation of results for the structure function of oriented membranes
在聚合膜的波动是通过广泛的分子动力学模拟简化«系绳表面»模型探索。与排斥性第二近邻相互作用相关的熵刚性导致了“幻面”的平坦化。在远距离自我回避存在下的吸引相互作用导致在足够低的温度下具有分形维数为3的膜坍塌。当吸引相互作用被关闭时,表面返回到先前模拟中发现的平坦相位。密度分布和六向内部秩序的研究允许对取向膜的结构功能结果进行简单的物理解释
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引用次数: 61
Interactions in mixtures of colloid and polymer 胶体和聚合物混合物中的相互作用
Pub Date : 1990-12-01 DOI: 10.1051/JPHYS:0199000510240281300
P. Tong, T. Witten, J. Huang, L. Fetters
Etude par diffusion optique aux petits angles de l'interaction entre un colloide stabilise par un agent de surface et le polyisoprene hydrogene. A l'aide d'un developpement du viriel, l'intensite de diffusion est calculee en fonction des concentrations en polymere et en colloide; la formule obtenue permet de mesurer le volume exclu mutuel entre le polymere et le colloide; le deuxieme coefficient du viriel des particules colloidales dans la solution diluee de polymere est aussi deduit. Cette methode d'obtention des parametres d'interaction dans un melange polymere-colloide est capable de sonder les changements du potentiel d'interaction de la suspension colloidale dus a l'addition du polymere (effet de depletion)
用小角度光学扩散研究表面活性剂稳定的胶体与聚异戊二烯氢之间的相互作用。利用viriel显影,计算扩散强度作为聚合物和胶体浓度的函数;所得到的公式允许测量聚合物和胶体之间的相互排除体积;还推导了稀释聚合物溶液中胶体颗粒的第二个维里尔系数。这种获得聚合物-胶体混合物相互作用参数的方法能够探测由于聚合物的加入而引起的胶体悬浮液相互作用电位的变化(耗竭效应)。
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引用次数: 17
A comment upon the use of two criteria in the identification of intrinsic esr in high Tc oxides 对鉴定高Tc氧化物中本征esr的两个判据的评述
Pub Date : 1990-12-01 DOI: 10.1051/JPHYS:0199000510240273900
A. Deville, B. Gaillard
An ESR signal detected in a Bi compound has recently been attributed to the SC phase, arguing that two criteria (value and thermal behaviour of the intensity) were met. We draw attention to the weakness of this argument, recalling a canonical example Un signal RPE observe dans un compose au bismuth a ete recemment attribue a la phase SC, en s'appuyant sur le fait que deux criteres (valeur et comportement thermique de l'intensite) sont verifies. Nous attirons l'attention sur la faiblesse de cette argumentation, et rappelons un exemple canonique
在Bi化合物中检测到的ESR信号最近被归因于SC相,认为满足两个标准(强度的值和热行为)。我们提请注意这一论点的弱点,回顾一个典型的例子,即非信号RPE观测数据不包含一个相位SC的初始值和初始值属性,即使其“适应性sur le fait que deux criteres”(值与分量热特性)也不验证。我们的注意力集中在我们的论证中,而不是在我们的论证中
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引用次数: 0
Direct reconstruction of pp elastic scattering amplitudes from experimental data between 0.83 and 2.7 GeV 从0.83 ~ 2.7 GeV的实验数据直接重建pp弹性散射振幅
Pub Date : 1990-12-01 DOI: 10.1051/JPHYS:0199000510230268900
C. Lac, J. Ball, J. Bystrický, J. Derégel, F. Lehár, A. Lesquen, L. Rossum, J. Fontaine, F. Perrot, P. Winternitz
The direct reconstruction of the elastic scattering amplitudes at eleven energies between 0.83 and 2.7 GeV is described. Complete sets of spin dependent observables used for this reconstruction were measured in the nucleon-nucleon experimental program at Saturne II. The invariant amplitudes a, b, c, d and e were deduced using the least square method fit to the experimental data. A search for solutions starting from random initial values was performed to determine different possible sets of amplitudes. The absolute values show a similar angular dependence at all energies and for all solutions. The dependence of phases show discrete ambiguities especially at the higher energies. One of the solutions at 2.1 GeV suggests a behaviour which could be related to a dibaryon resonance of mass 2.73 GeV with the half-width at the half-maximum less than 50 MeV.
描述了在0.83 ~ 2.7 GeV之间的11种能量下的弹性散射振幅的直接重建。在土星二号的核子-核子实验程序中测量了用于这种重建的自旋相关观测值的完整集合。用最小二乘法拟合实验数据,推导出了a、b、c、d和e的不变幅值。从随机初始值开始搜索解,以确定不同可能的振幅集。绝对值在所有能量和所有解下都表现出类似的角依赖性。相的依赖表现出离散的模糊性,特别是在高能量处。其中一个2.1 GeV的解表明,这种行为可能与质量为2.73 GeV的双重子共振有关,而半宽最大值的半宽小于50 MeV。
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引用次数: 17
Experimental evidence for deterministic chaos in electrochemical deposition 电化学沉积中确定性混沌的实验证据
Pub Date : 1990-11-01 DOI: 10.1051/JPHYS:0199000510210247700
F. Argoul, A. Arneodo
We report an experimental study of the statics and dynamics of electrodeposition of zinc in an aqueous medium, in the intermediate regime between dendritic and DLA-like metallic clusters. During the growth process, periodic and nonperiodic oscillations of the voltage are recorded under constant applied current intensity. Period-doubling bifurcations are identified. Analysis of the data in terms of phase portraits, Poincare maps and 1-D maps shows that the fractal geometry of these electrochemical deposits is the signature of a low-dimensional deterministic chaotic dynamics which displays sensitivity to initial conditions. The study of the apparently more complex dynamics recorded in the DLA limit is a very promising experimental challenge Nous presentons ici les resultats d'une etude experimentale du processus d'electrodeposition de zinc en milieu aqueux bidimensionnel. Les regimes etudies sont intermediaires entre des croissances metalliques de nature dendritique et des croissances plus desordonnees similaires aux agregats fractals engendres par simulation numerique de modele d'agregation limitee par la diffusion de Witten et Sander (DLA model). L'etude de ces dynamiques complexes apporte une premiere evidence experimentale du caractere chaotique deterministe de ces phenomenes de structuration d'interface et la signature d'une dynamique a faible nombre de degres de liberte. L'etude dynamique de regimes encore plus complexes observes dans la limite DLA s'avere etre un challenge experimental des plus prometteurs
我们报告了锌在水介质中电沉积的静力学和动力学的实验研究,在枝晶和dla类金属团簇之间的中间状态。在生长过程中,在恒定的施加电流强度下,记录了电压的周期性和非周期性振荡。确定了倍周期分岔。对相图、庞加莱图和一维图的数据分析表明,这些电化学沉积物的分形几何特征是低维确定性混沌动力学的特征,对初始条件敏感。研究在DLA极限下明显更复杂的动力学记录是一个非常有前途的实验挑战,Nous提出了在水相二维环境中锌电沉积过程的实验结果。Les研究了中间介质、自然介质、自然介质、树突介质、自然介质、自然介质、自然介质、自然介质、自然介质、自然介质、自然介质、自然介质、自然介质、自然介质、自然介质、自然介质、自然介质、自然介质、自然介质、自然介质、自然介质、自然介质、分形介质、自然介质、自然介质、分形介质、自然介质、分形介质、模拟介质、自然介质、聚集介质、有限介质、扩散介质等(DLA模型)。动力学复合体的性质是一个初步的证据,实验的性质是混沌的,确定的性质是现象的,结构的,界面的,动力学的特征是一个自由的程度。“纬度动力学”的制度,再加上复合体的观察,和“极限”的DLA,是一个无挑战的实验,再加上推动者
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引用次数: 16
Rheological Rouse model for a polymer in a nematic matrix 向列矩阵中聚合物的流变劳斯模型
Pub Date : 1990-11-01 DOI: 10.1051/JPHYS:0199000510220259500
F. Lequeux, R. Hocquart
A model of coupling between a mouse drain and a nematic order parameter is developed. The geometry of the chain for each mode, in simple shear flow is calculated. The local torque and normal stress sign are discussed. This implies non trivial ways to introduce the opposite coupling (from chain to parameter order) in order to get a model for mouse nematic polymers
建立了一个鼠漏和向列序参数耦合的模型。计算了简单剪切流中各模态链的几何形状。讨论了局部扭矩和正应力符号。这意味着引入相反耦合(从链到参数顺序)的非平凡方法,以获得小鼠向列相聚合物的模型
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引用次数: 1
Temperature dependent locally resolved 13C knight shifts in the organic conductor TTF[Ni(dmit)2]2 有机导体TTF[Ni(dmit)2]中温度依赖局部解析的13C骑士位移2
Pub Date : 1990-11-01 DOI: 10.1051/JPHYS:0199000510210246500
A. Vainrub, E. Canadell, D. Jérome, P. Bernier, T. Nunes, M. Bruniquel, P. Cassoux
High resolution 13 C NMR results for the organic conductor TTF[Ni(dmit) 2 ] 2 enriched by 13 C isotope in Ni(dmit) 2 molecules are reported. Variable temperature magic angle spinning experiments were performed between 160 and 295 K. Paramagnetic Knight shifts in the range 41-106.5 ppm at room temperature are observed for all Ni(dmit) 2 carbon sites. These shifts are slightly temperature dependent for inner carbons. However, for outer carbons, the shifts strongly decrease towards low temperature due to precursor effects of the charge density wave (CDW) transition. The results confirm the occurrence of both HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) conduction bands and are compared with calculated partial contributions of individual carbon atoms to the density of states at the Fermi level. We suggest that CDW effects above 160 K are associated with the LUMO bands
报道了Ni(dmit) 2分子中富集13c同位素的有机导体TTF[Ni(dmit) 2] 2的高分辨率13c核磁共振结果。在160 ~ 295 K范围内进行了变温魔角纺丝实验。在室温下,所有Ni(dmit) 2碳位的顺磁Knight位移范围为41-106.5 ppm。这些变化对内碳有轻微的温度依赖性。然而,对于外层碳,由于电荷密度波(CDW)跃迁的前驱效应,向低温方向的位移强烈减小。结果证实了HOMO(最高已占据分子轨道)和LUMO(最低未占据分子轨道)导带的存在,并与计算出的单个碳原子对费米能级态密度的部分贡献进行了比较。我们认为160k以上的CDW效应与LUMO波段有关
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引用次数: 10
Grain boundary premelting in crystalline benzene as studied by proton N.M.R. 质子核磁共振研究结晶苯的晶界预熔
Pub Date : 1990-11-01 DOI: 10.1051/JPHYS:0199000510210248900
C. Craven, G. Dosseh, B. Rousseau, A. Fuchs
The phenomenon of premelting has been investigated by proton n.m.r. in polycrystalline benzene of various purity. Our results suggest that premelting initiates at grain boundaries. The exact nature of the molten domains near the standard melting point is not yet clear but is presumably analogous to what is obtained in the surface melting experiments, i.e. a «strongly correlated interface liquid» Le phenomene de prefusion dans le benzene polycristallin de purete variable a ete etudie par r.m.n. du proton. Nos resultats suggerent que la prefusion debute aux joints de grains. La nature exacte des domaines fondus n'est pas encore tres claire mais il semble que l'on observe un liquide d'interface tres correle, comme les auteurs qui etudient la fusion de surface
用质子核磁共振法研究了不同纯度的多晶苯的预熔现象。结果表明,预熔始于晶界。标准熔点附近的熔融畴的确切性质尚不清楚,但可能类似于在表面熔化实验中得到的结果,即“强相关界面液体”,即预熔合现象,纯苯多晶变物和纯苯多晶变物的相互作用。结果表明,在晶粒的节理上进行预熔是可行的。“自然”精确地定义了“域”,“域”定义了“域”,“域”定义了“域”,“域”定义了“域”,“域”定义了“域”,“域”定义了“域”,“域”定义了“域”,“域”定义了“域”
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引用次数: 9
Performance enhancement of Willshaw type networks through the use of limit cycles 利用极限环提高Willshaw型网络的性能
Pub Date : 1990-11-01 DOI: 10.1051/JPHYS:0199000510210238700
G. Kohring
Simulation results of a Willshaw type model for storing sparsely coded patterns are presented. It is suggested that random patterns can be stored in Willshaw type models by transforming them into a set of sparsely coded patterns and retrieving this set as a limit cycle. In this way, the number of steps needed to recall a pattern will be a function of the amount of information the pattern contains. A general algorithm for simulating neural networks with sparsely coded patterns is also discussed, and, on a fully connected network of N=36864 neurons (1.4×10 9 couplings), it is shown to achieve effective updaping speeds as high as 1.6×10 11 coupling evaluations per second on one Cray-YMP processor
给出了一种存储稀疏编码模式的Willshaw型模型的仿真结果。建议将随机模式转换为稀疏编码模式集合,并将该集合作为极限环检索,从而将随机模式存储在Willshaw型模型中。通过这种方式,回忆模式所需的步骤数将是模式包含的信息量的函数。本文还讨论了一种用于模拟具有稀疏编码模式的神经网络的通用算法,并且,在N=36864个神经元(1.4×10 9个耦合)的全连接网络上,它被证明可以在一个cry - ymp处理器上实现高达每秒1.6×10 11次耦合评估的有效更新速度
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引用次数: 2
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Journal De Physique
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