There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Additive manufacturing of metallic components – Process, structure and properties

Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

This paper reviews the state-of-the-art of an important, rapidly emerging, manufacturing technology that is alternatively called additive manufacturing (AM), direct digital manufacturing, free form fabrication, or 3D printing, etc. A broad contextual overview of metallic AM is provided. AM has the potential to revolutionize the global parts manufacturing and logistics landscape. It enables distributed manufacturing and the productions of parts-on-demand while offering the potential to reduce cost, energy consumption, and carbon footprint. This paper explores the material science, processes, and business consideration associated with achieving these performance gains. It is concluded that a paradigm shift is required in order to fully exploit AM potential.

/pdf/metal-additive-manufacturing-a-review-lwo0wxslqj.pdf

Metal Additive Manufacturing: A Review

Natural structural materials are built at ambient temperature from a fairly limited selection of components. They usually comprise hard and soft phases arranged in complex hierarchical architectures, with characteristic dimensions spanning from the nanoscale to the macroscale. The resulting materials are lightweight and often display unique combinations of strength and toughness, but have proven difficult to mimic synthetically. Here, we review the common design motifs of a range of natural structural materials, and discuss the difficulties associated with the design and fabrication of synthetic structures that mimic the structural and mechanical characteristics of their natural counterparts.

Bioinspired structural materials

A circuit model approach is here presented to characterize bi-dimensional arrangements of dual-polarized elements. This contribution is an extension of the physical insightful approach previously proposed by some of the authors. The main novelty here resides in the fact that the scatterer may support two different current profiles. This feature becomes crucial for the accurate characterization of multiple current practical scenarios, such as the analysis and design of dual-polarized frequency selective surfaces. In particular, we illustrate its applicability when, due to oblique incidence, both an even and an odd current profiles are excited in a crossed-slot element.

http://ieeexplore.ieee.org/iel7/7474317/7481093/07481372.pdf

Pseudo-analytical circuits for dual-polarized FSS

Manufacturing patient-specific aortic dissection flow phantoms with compliant flaps

In this paper, it is demonstrated that complementary split ring resonators (CSRRs) and split ring resonators (SRRs) can be used to control the propagation in differential transmission lines. Specifically, it is shown that by etching CSRRs in the ground plane of a microstrip differential pair, the common (even) mode can be efficiently suppressed, this being of interest for common mode noise rejection. It is also demonstrated that the differential (odd) mode can be suppressed by merely etching SRRs in the upper substrate side, between the pair of transmission lines. These results are of interest in applications where differential lines are used, for instance, high speed digital circuits.

/pdf/differential-transmission-lines-loaded-with-split-ring-4y4iveixb6.pdf

Differential transmission lines loaded with split ring resonators (SRRs) and complementary split ring resonators (CSRRs)

Fast computation of quasi‐TEM parameters of multiconductor transmission lines with polygonal cross section

Some relevant effects associated with the circuit modeling of periodic structures with symmetric properties are explored in this work. In particular, the consequences of introducing a type of higher-order symmetry, the so-called glide symmetry, in the unit cell of a simple periodic structure are here discussed in terms of the electrical distance between the individual sub-cells of the periodic system. The value of this distance is shown to be very important in order to choose the appropriate method for obtaining the dispersion diagrams of the periodic structure.

Francisco Medina

Papers

Pseudo-analytical circuits for dual-polarized FSS

Manufacturing patient-specific aortic dissection flow phantoms with compliant flaps

Differential transmission lines loaded with split ring resonators (SRRs) and complementary split ring resonators (CSRRs)

Fast computation of quasi‐TEM parameters of multiconductor transmission lines with polygonal cross section

Considerations on the Usage of Transmission Matrices to Study the Dispersion Behavior of Glide-Symmetry Structures