Magnetic Nanocrystals Aligned on Mesoscopic Scale: Collective Properties and Their Use

Magnetic nanocrystals organized in chain-like structures behave as nanowires with a shape anisotropy induced by the structuration of the sample. This is valid for various types of magnetic nanomaterials. Furthermore, the coating of nanocrystals plays a major role in the mesoscopic structure of the film. γ-Fe₂O₃ nanocrystals are used as a mask to reproduce the mesoscopic structure on a silicon wafer.     

Simulation-based layout optimization for multi-station assembly lines

Journal of Intelligent Manufacturing - This article presents a novel approach for the automated 3D-layout planning of multi-station assembly lines. The planning method is based on a comprehensive...     

Joint of full-duplex relay,non-linear energy harvesting and multiple access in performance improvement of cell-edge user in heterogeneous networks

To serve massive connections in heterogeneous networks with respect to higher energy efficiency, we focus on new paradigm in order to achieve multiple access and performance improvement at cell-edge area. The power domain based non-orthogonal multiple access is introduced to address such problem. In particular, this paper studies a self-energy relay together with full-duplex scheme to implement cooperative power domain based non-orthogonal multiple access in small-cell system of the heterogeneous networks. In such small-cell network, a nearby user can be employed as a decode-and-forward with self-energy recycling protocol to assist a far power domain based non-orthogonal multiple access user (cell-edge user). The relay harvests energy from dedicated energy signal sent by a base station, while it still reuses energy from loop self-interference signal. To characterize the performance of the proposed system with respect to where meets weak signal condition, numerous expressions of exact outage probability for far power domain based non-orthogonal multiple access user is derived. Several practical scenarios are performed in three different schemes related to how energy harvesting architecture can be achieved. Based on analytical results, the optimal throughput achieved by the cell-edge user in small-cell network can be observed. Numerical results are presented to validate the accuracy of the derived results.

     

A consistent approach for fluid-structure-contact interaction based on a porous flow model for rough surface contact

Simulation approaches for fluid-structure-contact interaction, especially if requested to be consistent even down to the real contact scenarios, belong to the most challenging and still unsolved problems in computational mechanics. The main challenges are 2-fold—one is to have a correct physical model for this scenario, and the other is to have a numerical method that is capable of working and being consistent down to a zero gap. Moreover, when analyzing such challenging setups of fluid-structure interaction, which include contact of submersed solid components, it gets obvious that the influence of surface roughness effects is essential for a physical consistent modeling of such configurations. To capture this system behavior, we present a continuum mechanical model that is able to include the effects of the surface microstructure in a fluid-structure-contact interaction framework. An averaged representation for the mixture of fluid and solid on the rough surfaces, which is of major interest for the macroscopic response of such a system, is introduced therein. The inherent coupling of the macroscopic fluid flow and the flow inside the rough surfaces, the stress exchange of all contacting solid bodies involved, and the interaction between fluid and solid are included in the construction of the model. Although the physical model is not restricted to finite element–based methods, a numerical approach with its core based on the cut finite element method, enabling topological changes of the fluid domain to solve the presented model numerically, is introduced. Such a cut finite element method–based approach is able to deal with the numerical challenges mentioned above. Different test cases give a perspective toward the potential capabilities of the presented physical model and numerical approach.     

Electrospinning of ultrafine non-hydrolyzed silk sericin/PEO fibers on PLA: A bilayer scaffold fabrication

We report the feasibility of electrospinning of protein-polymer multilayered scaffolds with selected materials such as non-hydrolyzed silk sericin (SS), polyethylene oxide (PEO), and polylactic acid (PLA), with tuned fiber size and properties for each layer. We present a new innovative way for the electrospinning (ES) of non-hydrolyzed SS mixed with PEO yielding fibers with an average diameter ranging between 120 and 150 nm. Different SS:PEO ratios have been electrospun to study the effect of the concentration of SS protein on the fibers size and shape, as well and their electrospinnability. Electrospun SS:PEO fibers display weak to no mechanical resistance (non-measurable) and their deposition onto a sturdier scaffold is necessary to allow their use in biomedical and/or pharmaceutical fields. Therefore, bilayer scaffolds have been fabricated consisting of a PLA support and SS:PEO fibers obtained from the optimized SS:PEO ratio (1.2:4). They are composed of a sturdy hydrophobic layer of PLA fibers and a layer of sticky hydrophilic SS:PEO fibers. The scaffolds have been characterized extensively by Fourier transforms infra-red (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and their resistance to mechanical stress. Finally, hydrophobicity of both layers has been determined by measuring the contact angle of water droplets on the scaffolds, further proving the bilayer nature of the scaffolds.