Applications of Graphene at Microwave Frequencies

In view to the epochal scenarios that nanotechnology discloses, nano-electronics has the potential to introduce a paradigm shift in electronic systems design similar to that of the transition from vacuum tubes to semiconductor devices. Since low dimensional (1D and 2D) nano-structured materials exhibit unprecedented electro-mechanical properties in a wide frequency range, including radio-frequencies (RF), microwave nano-electronics provides an enormous and yet widely undiscovered opportunity for the engineering community. Carbon nano-electronics is one of the main research routes of RF/microwave nano-electronics. In particular, graphene has shown proven results as an emblematic protagonist, and a real solution for a wide variety of microwave electronic devices and circuits. This paper introduces graphene properties in the microwave range, and presents a paradigm of novel graphene-based devices and applications in the microwave/RF frequency range

Investigation of metal flow in bridge die extrusion of Alloy 6063 and subsequent effect on surface quality and weld seam integrity

This paper describes a detailed study of tube extrusion by simulation using finite element method (FEM). The finite element model used one-sixth of symmetry. The extrusion load, emperature evolution and metal flow were predicted. Innovative methods, combining both grid and surface tools, were used to define in detail the flow of material. These showed clearly the inner and outer surface formation mechanisms of the tube extrusion. The seam weld, an important quality indicator, was also evaluated by selecting an appropriate criterion

Current and Future Research Trends in Substrate Integrated Waveguide Technology

Substrate Integrated Waveguide (SIW) technology is the most promising candidate for the implementation of millimeter-wave (mm-wave) integrated circuits and systems for the next decade. Based on planar dielectric substrates with top and bottom metal layers perforated with metalized holes, SIW structures offer a compact, low loss, flexible, and cost-effective solution for integrating active circuits, passive components and radiating elements on the same substrate. This paper presents an overview of the current status and future trends of academic and industrial research on SIW technology. The historical development of SIW components and circuits is briefly outlined, and the current research topics are discussed: they include the development of numerical techniques for the modeling and design of SIW components, the investigation of novel compact and broadband interconnects, the determination of design solutions for loss minimization. Future research trends are also discussed: they mainly aim at the implementation of SIW components at higher frequency (60-350 GHz) and the integration of complete Systems-on-Substrate (SoS)

Distribution of deer keds (Diptera: Hippoboscidae) in free-living cervids of the Tuscan-Emilian Apennines, central Italy, and establishment of the allochthonous ectoparasite Lipoptena fortisetosa

Lipoptena fortisetosa and L. cervi are hematophagous ectoparasites belonging to the Hippoboscidae family and preferentially living on cervids. In recent years, they have received specific attention due to the great increase in the abundance of their host species, and to their medical and veterinary importance as possible vectors of pathogens harmful to humans and animals. The aim of this study was to investigate the parasitism level of both of these flies on their main hosts in Italy, which are red deer, fallow deer, and roe deer, and to highlight a possible preference for a species, sex, or age class among the hosts. Deer keds were collected by examining 326 cervids hunted in the Tuscan-Emilian Apennines. Outcomes showed that L. fortisetosa has greatly spread throughout the study area, where it competes with the autochthonous L. cervi. Moreover, red deer was the favored host species of both ectoparasites, while different preferences for host sex and age classes were observed in the two hippoboscids. The regular monitoring of deer ked populations, especially the allochthonous L. fortisetosa, which is continuously spreading in Europe, is recommended to expand the knowledge on these parasitic species that are potentially dangerous to public health