摘要:

Polymeric materials often have the topological transformation such as the fracture, but the simulation of these systems is difficult for the nonlinearity and the topological exchange. We perform FEM fracture simulations using a Delaunay triangular lattice in the Eulerian-Lagrangian pictures. We calculated the stress, the diverged stress profile around the edge, andJ⁁-integral using a virtual crack extension method in our simulator. Then we introduce the crack generation and evolution on the multi droplet system and the gel shrinking system. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291566

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291567

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We develop a General Fluctuation Formula for phase variables that are odd under time reversal. Simulations are used to verify the new formula. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291568

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We improve a lattice model of water introduced by Sastry, Debenedetti, Sciortino, and Stanley to give insight on experimental thermodynamic anomalies in supercooled phase, taking into account the correlations between intra-molecular orientational degrees of freedom. The original Sastry et al. model including energetic, entropic and volumic effect of the orientation-dependent hydrogen bonds (HBs), captures qualitatively the experimental water behavior, but it ignores the geometrical correlation between HBs. Our mean-field calculation shows that adding these correlations gives a more water-like phase diagram than previously shown, with the appearance of a solid phase and first-order liquid-solid and gas-solid phase transitions. Further investigation is necessary to be able to use this model to characterize the thermodynamic properties of the supercooled region. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291569

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We examine the synchronization phenomena in a set of globally coupled oscillators with particular attention to the interplay between external driving and inertia or noise. From the self-consistency equation for the order parameter, which measures the collective synchronization of the system, it is found that the inertia brings on discontinuous transitions between the coherent and incoherent states and gives rise to hysteresis behavior. It is also shown that the total order parameter decreases monotonically with noise, indicating overall suppression of synchronization. Still there exist optimal noise levels at which the ac components of the order parameter and of the phase velocity reaches their maxima. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291570

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We study a model of interacting thermally-activated subsystems which can be thought of as a hybrid between the glass model of Bouchaud and the the Bak-Sneppen model of self-organised criticality. The model has two parameters, a temperatureTand an interaction frequencyz. By considering the model in its mean field form, it is shown that Bouchaud’s trap model and the Bak-Sneppen model are recovered in the limitsz=0andT→0+,respectively. The consequences of recent claims of aging in the critical state are also discussed. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291571

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Structural changes and folding properties of 2- and 3-dimensional di-block polyampholytes are investigated via multicanonical molecular dynamics simulations. The restricted free energy of the 2-dimensional system clearly shows double well structure at intermediate temperature region, which is indicative of the structural transition between extended and compact structures. In the 3-dimensional system, only single well structure in the restricted free energy is observed. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291572

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

In the early 50’s, Lee and Yang developed the theory of phase transitions based on the singular nature of partition function in the complex parameter space. Ever since there have been a long history of extensive study of the behavior of the partition function in the complex temperature plane near the phase transition point as well as the critical point. Recent study reveals that the so-called Lee-Yang circle theorem is a special case of a more general mathematical relation in the probability theory in the case of the first order phase transition. On the other hand the finite size scaling theory shows that the complex temperature behavior of the partition function at the critical point has a unique scaling behavior. Instead of zeros of the partition function there is a flat region where the complex partion function vanishes as one moves away from the critical point. We will discuss these recent findings. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291573

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Chain dynamics of poly(&agr;-mehylstyrene) of high molecular weight in benzene, a good solvent, in dilute solution was investigated by dynamic light scattering under Couette flow. At the shear gradient above 2.8–4.5 s−1, the internal modes of motions were exclusively suppressed and only the center-of-mass translational diffusion motion of the chain was detected. Whereas, in the intermediate shear region, the decay rate for the internal mode was constant but that for the diffusion mode increased with increasing the shear rate. The obtained universal ratio&OHgr;/D0q2was located close to the theoretical curve predicted for flexible chains under themicroscopicdescription of chain dynamics in the &THgr; state. This quantitative agreement between theory and experiments means that the coupled kinetic equations for chain segments and solvent in the same dynamic level is indispensable for describing rigorously chain dynamics in dilute solution. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291574

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

By limiting the trajectory of a diffusing particle to the vicinity of the classical path, the equation which governs the time evolution of the particle distribution in position and velocity is derived and discussed. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291575

出版商:AIP    

年代:1900

数据来源: AIP