Electromagnetic analysis and performance comparison of fully 3D-printed antennas

In this work, the possibility of directly prototyping antennas by exploiting additive manufacturing 3D-printing technology is investigated. In particular, the availability of printable filaments with interesting conductive properties allows for printing of even the antenna conductive elements. Three samples of a 2.45 GHz microstrip patch antenna have been 3D-printed by using different approaches and materials, and their performance evaluated and compared. In particular, the same dielectric substrate printed in polylactic acid (PLA) has been adopted in all cases, whilst copper tape and two different conductive filaments have been used to realize the conductive parts of the three antenna samples, respectively. Even if an expected radiation efficiency reduction has been observed for the conductive filament case, the comparative analysis clearly demonstrates that 3D-printing technology can be exploited to design working fully-printed antennas, including the conductive parts

An Exploration of Home Attachment Representations using an Adaptation of Adult Attachment Interview: Preliminary Data on the Home Attachment Interview

Background: In analysing the literature on household as a physical structure strongly linked to cultural and affective aspects, as well as to universal central psychological needs, a universe of meanings was found. The household, conceptualised as home and safe shelter that contains and protects, but also as a favourite place where the most important relationships of each human being unfold, suggests to use attachment theory perspective as a potentially useful framework to conceptualize the construct of home attachment. However, this perspective needs to be further investigated in order to understand its complex nature. Therefore, this pilot study aims to investigate how individuals represent their own homes according to their feelings and emotions related to their household.Methods: A qualitative-quantitative survey has been carried out with 50 adults (50% females) divided into five different age groups (from late adolescence to old age). An adapted version of the Adult Attachment Interview, the Home Attachment Interview, was administered.Results: Analysis identified the relevant aspects that distinguish the "house" as a physical structure, and the "home", that symbolically encloses emotional and affective experiences suggesting a perception of the "house" as "home", being a special place characterised by a strong attachment relationship connoted symbolically and affectively.Conclusions: Attachment theoretical and methodological tools used in the study appear especially useful to investigate and understand the construct of home attachment

Optimal Interface Conditions for Domain Decomposition Methods

We define optimal interface conditions for the additive Schwarz method (ASM) in the sense that convergence is achieved in a number of steps equals to the number of subdomains. Since these boundary conditions are difficult to use, we approximate them by partial differential operators that are easier to use. We present numerical results using these approximate interface conditions for the ASM and Schur type methods (substructuring). We also give a new result of convergence for BiCG which is then used for BiCGSTAB

Guidelines for Identifying Homologous Recombination Events in Influenza A Virus

The rapid evolution of influenza viruses occurs both clonally and non-clonally through a variety of genetic mechanisms and selection pressures. The non-clonal evolution of influenza viruses comprises relatively frequent reassortment among gene segments and a more rarely reported process of non-homologous RNA recombination. Homologous RNA recombination within segments has been proposed as a third such mechanism, but to date the evidence for the existence of this process among influenza viruses has been both weak and controversial. As homologous recombination has not yet been demonstrated in the laboratory, supporting evidence, if it exists, may come primarily from patterns of phylogenetic incongruence observed in gene sequence data. Here, we review the necessary criteria related to laboratory procedures and sample handling, bioinformatic analysis, and the known ecology and evolution of influenza viruses that need to be met in order to confirm that a homologous recombination event occurred in the history of a set of sequences. To determine if these criteria have an effect on recombination analysis, we gathered 8307 publicly available full-length sequences of influenza A segments and divided them into those that were sequenced via the National Institutes of Health Influenza Genome Sequencing Project (IGSP) and those that were not. As sample handling and sequencing are executed to a very high standard in the IGSP, these sequences should be less likely to be exposed to contamination by other samples or by laboratory strains, and thus should not exhibit laboratory-generated signals of homologous recombination. Our analysis shows that the IGSP data set contains only two phylogenetically-supported single recombinant sequences and no recombinant clades. In marked contrast, the non-IGSP data show a very large amount of potential recombination. We conclude that the presence of false positive signals in the non-IGSP data is more likely than false negatives in the IGSP data, and that given the evidence to date, homologous recombination seems to play little or no role in the evolution of influenza A viruses

Modelling of dielectric barrier discharge plasma actuators for direct numerical simulations

In recent years the development of devices known as plasma actuators has advanced the promise of controlling flows in new ways that increase lift, reduce drag and improve aerodynamic efficiencies; advances that may lead to safer, more efficient and quieter aircraft. The large number of parameters (location of the actuator, orientation, size, relative placement of the embedded and exposed electrodes, materials, applied voltage, frequency) affecting the performance of plasma actuators makes their development, testing and optimisation a very complicated task. Several approaches have been proposed for developing numerical models for plasma actuators. The discharge can be modelled by physics-based kinetic methods based on first principles, by semi-empirical phenomenological approaches and by PIV-based methods where the discharge is replaced by a steady-state body force. The latter approach receives a recent interest for its easy implementation in RANS and U-RANS solvers. Here, a forcing term extracted from experiments is implemented into our high-order Navier-Stokes solver (DNS) in order to evaluate its robustness and ability to mimic the effects of a surface dielectric barrier discharge. This experimental forcing term is compared to the numerical forcing term developed by Suzen & Huang (1, 2) with an emphasis on the importance of the wall-normal component of each model

An analysis of teachers’ instructions and feedback at a contemporary dance university

Background: Given the demands posed by excessive practice quantities in modern dance, physical and mental health can be compromised. Therefore, there is a need to consider how quality of practice may be improved and possibly even reduce training times. Sports literature has shown that instructions and feedback given by coaches can have an effect on the quality of training and influence self-regulation and the performance of athletes. However, currently little is known about the use of instructions and feedback by dance teachers. The aim of the current study was, therefore, to examine the type of instructions and feedback given by dance teachers during various dance classes. Methods: A total of six dance teachers participated in this study. Video and audio recordings were made of six dance classes and two rehearsals at a contemporary dance university. The dance teacher’s coaching behavior was analyzed using the modified Coach Analysis and Intervention System (CAIS). Additionally, feedback and instructions were also examined in terms of their corresponding focus of attention. Absolute numbers, as well as times per minute (TPM) rates were calculated for each behavior before, during, and after an exercise. Absolute numbers were also used to calculate ratios of positive-negative feedback and open-closed questions. Results: Most feedback comments were given after an exercise (472 out of 986 total observed behaviors). Improvisation had the highest positive-negative feedback ratio (29) and open-closed questions ratio (1.56). Out of the focus of attention comments, internal focus of attention comments were used most frequently (572 out of 900). Discussion/conclusion: The results make clear that there is a large variability in instructions and feedback over teachers and classes. Overall, there is room for improvement toward a higher positive-negative feedback ratio, a higher open-closed question ratio and producing more comments eliciting an external focus of attention.</p

A novel 60 GHz wideband coupled half-mode/quarter-mode substrate integrated waveguide antenna

A novel wideband substrate integrated waveguide (SIW) antenna topology, consisting of coupled half-mode and quarter-mode SIW resonant cavities, is proposed for operation in the 60 GHz band. This innovative topology combines a considerable bandwidth enhancement and a low form factor with compatibility with low-cost printed circuit board manufacturing processes, making it excellently suited for the next generation, high data rate wireless applications. Moreover, exploiting SIW technology, a high antenna-platform isolation is obtained, enabling dense integration with active electronics without harmful coupling. The computer-aided design process yields an antenna that covers the entire 57-64 GHz IEEE 802.11ad band with a measured fractional impedance bandwidth of 11.7% (7 GHz). The measured maximum gain and radiation efficiency of the prototype are larger than 5.1 dBi and 65%, respectively, within the entire impedance bandwidth

Observing Conditions at Mt.Graham: VATT UBVR Sky Surface Brightness and Seeing Measurements from 1999 through 2003

We present measurements of sky surface brightness and seeing on Mt.Graham obtained at the Vatican Advanced Technology Telescope (VATT) during 16 observing runs between April 1999 and December 2003. We show that the sky surface brightness is significantly darker during photometric conditions, and can be highly variable over the course of a single observing run as well as from one run to the next, regardless of photometricity. In our photometric observations we find an average low-airmass (sec z < 1.2) sky surface brightness of 22.00, 22.53, 21.49, and 20.88 mag arcsec^-2 in U, B, V, and R, respectively. The darkest run (02/00 in U and 02/01 in BVR) had an average sky surface brightness of 22.38, 22.86, 21.72, and 21.19 mag arcsec^-2 in U, B, V, and R, respectively. With these results we show that under the best conditions, Mt. Graham can compete with the darkest sites in Hawaii and Chile, thanks in part to the strict dark-sky ordinances in place in Tucson and Safford. We expect the sky over Mt. Graham to be even darker than our 1999--2003 results during solar minimum (2006--2007). We find a significant improvement of about 0.45 arcsec in our measured stellar FWHM after improvements to the telescope were made in Summer and Fall 2001. Stellar FWHM values are highly variable, with median R-band focus FWHM values in each observing run ranging from 0.97 arcsec to 2.15 arcsec. Significantly sub-arcsecond seeing was occasionally achieved with values as low as 0.65 arcsec FWHM in R. There may possibly still be a significant telescope contribution to the seeing at the VATT, but nearby trees as high as the dome are currently the dominant factor.Comment: 22 pages, 11 figures, to appear in PAS