Parametric Study of the Device Angle Dependency of a Single Vortex Generator on a Flat Plate

Ponencia presentada en el 10th World Congress on Computational Mechanics (WCCM 2012), Sao Paulo (Brazil).Publicados los abstracts en documento con ISBN: 978-85-86686-69-6.

Advances in Click Chemistry for Single-Chain Nanoparticle Construction

Single-chain polymeric nanoparticles are artificial folded soft nano-objects of ultra-small size which have recently gained prominence in nanoscience and nanotechnology due to their exceptional and sometimes unique properties. This review focuses on the current state of the investigations of click chemistry techniques for highly-efficient single-chain nanoparticle construction. Additionally, recent progress achieved for the use of well-defined single-chain nanoparticles in some promising fields, such as nanomedicine and catalysis, is highlighted.

Hydroelectric Voltage Generation Based On Water-Filled Single-Walled Carbon Nanotubes

A DFT/MD mutual iterative method was employed to give insights into the mechanism of voltage generation based on water-fitted single-walled carbon nanotubes (SWCNTs). Our calculations showed that a constant voltage difference of several mV would generate between the two ends of a carbon nanotube, due to interactions between the water dipole chains and charge carriers in the tube. Our work validates this structure of a water-fitted SWCNT as a promising candidate for a synthetic nanoscale power cell, as well as a practical nanopower harvesting device at the atomic level. 

Transport Properties And Induced Voltage In The Structure Of Water-Filled Single-Walled Boron-Nitrogen Nanotubes

Density functional theory/molecular dynamics simulations were employed to give insights into the mechanism of voltage generation based on a water-filled single-walled boron-nitrogen nanotube (SWBNNT). Our calculations showed that (1) the transport properties of confined water in a SWBNNT are different from those of bulk water in view of configuration, the diffusion coefficient, the dipole orientation, and the density distribution, and (2) a voltage difference of several millivolts would generate between the two ends of a SWBNNT due to interactions between the water dipole chains and charge carriers in the tube. Therefore, this structure of a water-filled SWBNNT can be a promising candidate for a synthetic nanoscale power cell as well as a practical nanopower harvesting device.

Formation of Single and Multiple Deformation Twins in Nanocrystalline fcc Metals

Deformation twins are often observed to meet each other to form multi-fold twins in nanostructured face-centered cubic (fcc) metals.Here we propose two types of mechanism for the nucleation and growth of four different single and multiple twins. These mechanisms provide continuous generation of twinning partials for the growth of the twins after ucleation. A relatively high stress or high strain rate is needed to activate these mechanisms, making them more prevalent in nanocrystalline materials than in their coarse-grained counterparts.Experimental observations that support the proposed mechanisms are presented.

A comparative study of Young's modulus of single-walled carbon nanotube by CPMD, MD, and first principle simulations

Carbon nanotubes (CNTs), due to their exceptional magnetic, electrical and mechanical properties, are promising candidates for several technical applications ranging from nanoelectronic devices to composites. Young's modulus holds the special status in material properties and micro/nano-electromechanical systems (MEMS/NEMS) design. The excellently regular structures of CNTs facilitate accurate simulation of CNTs' behavior by applying a variety of theoretical methods. Here, three representative numerical methods, i.e., Car-Parrinello molecular dynamics (CPMD), density functional theory (DFT) and molecular dynamics (MD), were applied to calculate Young's modulus of single-walled carbon nanotube (SWCNT) with chirality (3,3). The comparative studies showed that the most accurate result is offered by time consuming DFT simulation. MID simulation produced a less accurate result due to neglecting electronic motions. Compared to the two preceding methods the best performance, with a balance between efficiency and precision, was deduced by CPMD.

A surface energy model and application to mechanical behavior analysis of single crystals at sub-micron scale

Size effects of mechanical behaviors of materials are referred to the variation of the mechanical behavior due to the sample sizes changing from macroscale to micro-/nanoscales. At the micro-/nanoscale, since sample has a relatively high specific surface area (SSA) (ratio of surface area to volume), the surface although it is often neglected at the macroscale, becomes prominent in governing the energy effect, although it is often neglected at the macroscale, becomes prominent in governing the mechanical behavior. In the present research, a continuum model considering the surface energy effect is developed through introducing the surface energy to total potential energy. Simultaneously, a corresponding finite element method is developed. The model is used to analyze the axial equilibrium strain problem for a Cu nanowire at the external loading-free state. As another application of the model, from dimensional analysis, the size effects of uniform compression tests on the microscale cylinder specimens for Ni and Au single crystals are analyzed and compared with experiments in literatures. (C) 2009 Elsevier B.V. All rights reserved.