F. Aymerich¹, M. Serra²

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 49-66, 2006, DOI:10.3970/cmes.2006.013.049

Abstract The study reported in this paper explores the potential of Ant Colony Optimization (ACO) metaheuristic for stacking sequence optimization of composite laminates. ACO is a recently proposed population-based search approach able to deal with a wide range of optimization problems, especially of a combinatorial nature, and inspired by the natural foraging behavior of ant colonies. ACO search processes, in which the activities of real ants are simulated by means of artificial agents that communicate and cooperate through the modification of the local environment, were implemented in a specifically developed numerical algorithm aimed at the lay-up… More >

R. Vignjevic¹, T. De Vuyst², J. C. Campbell¹

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 35-48, 2006, DOI:10.3970/cmes.2006.013.035

Abstract An approach to the treatment of contact problems involving frictionless sliding and separation under large deformations in meshless methods is proposed. The method is specially suited for non-structured spatial discretisation. The contact conditions are imposed using a contact potential for particles in contact. Inter-penetration is checked as a part of the neighbourhood search. In the case of conventional SPH contact conditions are enforced on the boundary layer 2h thick while in the case of the normalized SPH contact conditions are enforced for the particles lying on the contact surface. The implementation of the penalty based More >

P.M. Baiz¹, M.H. Aliabadi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 19-34, 2006, DOI:10.3970/cmes.2006.013.019

Abstract In this paper the linear buckling problem of elastic shallow shells by a shear deformable shell theory is presented. The boundary domain integral equations are obtained by coupling two dimensional plane stress elasticity with boundary element formulation of Reissner plate bending. The buckling problem is formulated as a standard eigenvalue problem, in order to obtain directly critical loads and buckling modes as part of the solution. The boundary is discretised into quadratic isoparametric elements while in the domain quadratic quadrilateral cells are used. Several examples of cylindrical shallow shells (curved plates) with different dimensions and More >

Luigi Morino¹, Giovanni Bernardini¹, Franco Mastroddi²

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 1-18, 2006, DOI:10.3970/cmes.2006.013.001

Abstract The paper presents an overview of recent work by the authors and their collaborators on multi--disciplinary optimization for conceptual design, based on the integrated modeling of structures, aerodynamics, and aeroelasticity. The motivation for the work is the design of innovative aircraft configurations, and is therefore first--principles based, since in this case the designer cannot rely upon past experience. The algorithms used and the philosophy behind the choices are discussed. More >

Wendong Shi^∗,†, Xi-Qiao Feng^*, Huajian Gao^†

Molecular & Cellular Biomechanics, Vol.3, No.3, pp. 121-126, 2006, DOI:10.3970/mcb.2006.003.121

Abstract When pulling a vesicle adhered on a substrate, both the force-displacement profile and the maximum force at pull-off are sensitively dependent upon the substrate shape. Here we consider the adhesion between a two-dimensional vesicle and a rigid substrate via long-range molecular interactions. For a given contact area, the theoretical pull-off force of the vesicle is obtained by multiplying the theoretical strength of adhesion and the contact area. It is shown that one may design an optimal substrate shape to achieve the theoretical pull-off force. More >

Baohua Ji^*, Yonggang Huang^†

Molecular & Cellular Biomechanics, Vol.3, No.3, pp. 109-120, 2006, DOI:10.3970/mcb.2006.003.109

Abstract The mechanisms governing the self-assembled structure of biomolecules (single chain and bundle of chains) are studied with an AB copolymer model via the coarse grained molecular dynamics simulations. Non-local hydrophobic interaction is found to play a critical role in the pattern formation of the assembled structure of polymer chains. We show that the polymer structure could be controlled by adjusting the balance between local (short range) and non-local (long range) hydrophobic interaction which are influenced by various factors such as the sequences, chain length, stiffness, confinement, and the topology of polymers. In addition, the competition More >

X. Edward Guo^∗,†,‡, Erica Takai^∗,‡, Xingyu Jiang^§, Qiaobing Xu^§, George M. Whitesides^§, James T. Yardley^¶, Clark T. Hung^*, Eugene M. Chow^||, Thomas Hantschel^∗∗, Kevin D. Costa^∗

Molecular & Cellular Biomechanics, Vol.3, No.3, pp. 95-108, 2006, DOI:10.3970/mcb.2006.003.095

Abstract In this study, bone cells were successfully cultured into a micropatterned network with dimensions close to that of in vivo osteocyte networks using microcontact printing and self-assembled monolyers (SAMs). The optimal geometric parameters for the formation of these networks were determined in terms of circle diameters and line widths. Bone cells patterned in these networks were also able to form gap junctions with each other, shown by immunofluorescent staining for the gap junction protein connexin 43, as well as the transfer of gap-junction permeable calcein-AM dye. We have demonstrated for the first time, that the intracellular More >

Yong Gan^*, Zhen Chen^∗,†

Molecular & Cellular Biomechanics, Vol.3, No.3, pp. 89-94, 2006, DOI:10.3970/mcb.2006.003.089

Abstract Due to their nanoscale size and special features, carbon nanotubes could enter the human body via certain way. The growing use of carbon nanotubes in practical applications, hence, prompts a necessity to study the potential health risks of carbon nanotubes. A numerical study is performed in this paper to investigate the size effect of carbon nanotubes on the bulk modulus of a lipid bilayer by using the constant surface tension molecular dynamics simulation procedure. It is found that the size effect is not monotonic with the increase of nanotube length. An explanation is given on More >

Meghan H. Hoskins^*, Cheng Dong^∗,†

Molecular & Cellular Biomechanics, Vol.3, No.2, pp. 79-88, 2006, DOI:10.3970/mcb.2006.003.079

Abstract It has been determined previously that polymorphonuclear leukocytes, or PMNs, can facilitate melanoma cell extravasation through the endothelium under shear conditions [1,2]. The interactions between melanoma cells and PMNs are mediated by the β₂-integrins expressed by PMNs and intercellular adhesion molecules (ICAM-1) expressed on melanoma cells. In this study, the kinetics of these interactions was studied using a parallel plate flow chamber. The dissociation rates were calculated under low force conditions for ICAM-1 interactions with both β₂-integrins, LFA-1 (CD11a/CD18) and Mac-1 (CD11b/CD18), together and separately by using functional blocking antibodies on PMNs. The kinetics of PMNs More >

Jui-Ming Yang^*, Philip R. LeDuc^∗,†

Molecular & Cellular Biomechanics, Vol.3, No.2, pp. 69-78, 2006, DOI:10.3970/mcb.2006.003.069

Abstract Inorganic and organic integrated systems detect, process, and respond to signals from solid media. Advances in fluidic systems have offered an alternative to traditional signaling methods through the development of aqueous signaling systems. Here, we show an experimentally simple mechanically governed fluidic system that creates three-dimensional molecular multiphase separation in a combination of discrete and continuous gradients analogous to digital and analog signals that can be used for controlled spatiotemporal cellular stimulation. We accomplish the pattern formation by fabricating a compartmentalized multi-level fluidics device where a network of capillaries converges into a main channel. Simultaneous More >