Exceptionally large room-temperature ferroelectric polarization in the novel PbNiO3 multiferroic oxide

We present a study based on several advanced First-Principles methods, of the recently synthesized PbNiO3 [J. Am. Chem. Soc 133, 16920 (2011)], a rhombohedral antiferromagnetic insulator which crystallizes in the highly distorted R3c crystal structure. We find this compound electrically polarized, with a very large electric polarization of about 100 (\muC/cm)^2, thus even exceeding the polarization of well-known BiFeO3. PbNiO3 is a proper ferroelectric, with polarization driven by large Pb-O polar displacements along the [111] direction. Contrarily to naive expectations, a definite ionic charge of 4+ for Pb ion can not be assigned, and in fact the large Pb 6s-O 2p hybridization drives the ferroelectric distortion through a lone-pair mechanism similar to that of other Pb- and Bi-based multiferroic

Incoherently pumped continuous wave optical parametric oscillator broadened by non-collinear phasematching

In this paper, we report on a singly resonant optical parametric oscillator (OPO) pumped by an amplified spontaneous emission (ASE) source. The pump focusing conditions allow non-collinear phasematching, which resulted in a 230 nm (190 cm$^{-1}$) spectral bandwidth. Calculations indicate that such phasematching schemes may be used to further broaden OPO spectral bandwidths.Comment: 7 pages 4 figure

Intertwined Rashba, Dirac and Weyl Fermions in Hexagonal Hyperferroelectrics

By means of density functional theory based calculations, we study the role of spin-orbit coupling in the new family of ABC hyperferroelectrics [Phys. Rev. Lett. 112, 127601 (2014)]. We unveil an extremely rich physics strongly linked to ferroelectric properties, ranging from the electric control of bulk Rashba effect to the existence of a three dimensional topological insulator phase, with concomitant topological surface states even in the ultrathin film limit. Moreover, we predict that the topological transition, as induced by alloying, is followed by a Weyl semi-metal phase of finite concentration extension, which is robust against disorder, putting forward hyperferroelectrics as promising candidates for spin-orbitronic applications.Comment: 5 pages, 3 figure

Load-carrying capacity of compressed wall-like RC columns strengthened with FRP

The analytical prediction of the effectiveness of fiber-reinforced polymer (FRP) in the confinement of a rectangular reinforced concrete (RC) column with a high aspect ratio (wall-like) still has an uncertain solution. In this paper, a numerical investigation of the axial response of RC wall-like columns strengthened with FRP systems was developed. Analytical solutions proposed in the literature for the assessment of the axial load capacity were presented and compared with each other and with the available experimental results. Moreover, non-linear finite element analysis was carried out, and the results were discussed, providing a simple model for the assessment of the axial compressive strength of wall-like RC columns strengthened with FRP

Probabilistic assessment of footbridge response to single walkers

Among the load scenarios considered for the serviceability assessment of human-induced footbridge vibration, is that of the transient action of a single pedestrian or a small group of pedestrians. Although such action is stochastic due to the variability of gait parameters, available Codes and Guidelines all assume it is deterministic and equal to that coming from the “worst pedestrian ever” for the given footbridge. This approach is sound from an engineering point of view but does not allow control of the probability of failure. The present work deals with a reliability-based procedure for the serviceability assessment of the footbridge peak characteristic accelerations due to pedestrian induced actions. Based on the results obtained incorporating the effects of the inter-subject variability of gait parameters and of the uncertainties in footbridge dynamic properties, a design response spectrum is proposed for both vertical and lateral vibrations. The proposed procedure lends itself for immediate Code implementation

Quality-aware mashup composition: issues, techniques and tools

Web mashups are a new generation of applications based on the composition of ready-to-use, heterogeneous components. In different contexts, ranging from the consumer Web to Enterprise systems, the potential of this new technology is to make users evolve from passive receivers of applications to actors actively involved in the creation of their artifacts, thus accommodating the inherent variability of the users’ needs. Current advances in mashup technologies are good candidates to satisfy this requirement. However, some issues are still largely unexplored. In particular, quality issues specific for this class of applications, and the way they can guide the users in the identification of adequate components and composition patterns, are neglected. This paper discusses quality dimensions that can capture the intrinsic quality of mashup components, as well as the components’ capacity to maximize the quality and the userperceived value of the overall composition. It also proposes an assisted composition process in which quality becomes the driver for recommending to the users how to complete mashups, based on the integration of quality assessment and recommendation techniques within a tool for mashup development

Feasibility analysis for floating offshore wind energy

Purpose The assessment of the economic feasibility of foating ofshore wind farms (FOWFs) plays an important role in the future possible spreading of this challenging technology in the wind power industry. The use of specifc economic analyses is fundamental to point out the potential of FOWFs and to sustain their technical value. Within this topic, the implementation of the FOWF life cycle cost model and producibility analysis in a geographic information system is developed, with the aim of carrying out a feasibility analysis at the territorial scale, for diferent types of foater. Moreover, a simplifed model for a quick life cycle cost assessment is proposed and calibrated. Methods The available cost model is frst validated comparing the costs of FOWFs based on diferent foaters (Semi-Submersible Platform—SSP, Spar Buoy—SB and Tension Leg Platform—TLP) with corresponding results available in the literature. Then, it is implemented in QGIS to be used for territorial-scale analyses and sensitivity analyses of the cost parameters. A feasibility analysis is developed through the main fnancial parameters. Finally, the results are then used to calibrate a simplifed version of the cost model that depends on three main parameters, namely distance to shore, distance from the port of operation and bathymetry. Results and discussion The FOWF cost values are found to be in good agreement with those coming from analytical methods similar to the one from the authors. However, some discrepancies with those based on average costs are observed. Then, the results of the sensitivity analysis are presented as life cycle cost maps, giving an overall picture of the variation of the total cost of FOWF installations on a reference domain. The results show that among the three types of foaters considered here, the SSP proved to be the most promising one, giving lower costs than the SB and the TLP. Moreover, a good agreement between the results in terms of total cost of FOWFs calculated with the analytical and simplifed models for SSPs, SBs and TLPs is observed. Finally, the feasibility analysis showed that the fnancial parameters are more infuenced by the wind speed than by the cost of the farm. Conclusions The paper aims to provide guidance on how to carry out feasibility analyses of a specifc site for FOWF installation, thus supporting decision-making procedures. The approach and the results presented here are meant for use in the early stage of the decision-making process, as a tool for the assessment of the economic feasibility of FOWFs installation

The Relationship between Wind Pressure and Pressure Coefficients for the Definition of Wind Loads on Buildings

Wind induced pressures on buildings are the product of a velocity pressure and a pressure coefficient. The way in which these two quantities are calculated has changed over the years, and Design Codes have been modified accordingly. This paper tracks the evolution of the approach to wind loading of buildings from the practice in the 1950s, mainly referring to the Swiss Code SIA, to the most recent advances including probabilistic methods, internet databases, and advanced modelling of meteorological phenomena

Electric fields and valence band offsets at strained [111] heterojunctions

[111] ordered common atom strained layer superlattices (in particular the common anion GaSb/InSb system and the common cation InAs/InSb system) are investigated using the ab initio full potential linearized augmented plane wave (FLAPW) method. We have focused our attention on the potential line-up at the two sides of the homopolar isovalent heterojunctions considered, and in particular on its dependence on the strain conditions and on the strain induced electric fields. We propose a procedure to locate the interface plane where the band alignment could be evaluated; furthermore, we suggest that the polarization charges, due to piezoelectric effects, are approximately confined to a narrow region close to the interface and do not affect the potential discontinuity. We find that the interface contribution to the valence band offset is substantially unaffected by strain conditions, whereas the total band line-up is highly tunable, as a function of the strain conditions. Finally, we compare our results with those obtained for [001] heterojunctions.Comment: 18 pages, Latex-file, to appear in Phys.Rev.

Educating and Training in Research Integrity (RI): A Study on the Perceptions and Experiences of Early Career Researchers Attending an Institutional RI Course

Research integrity (RI) is defined as adherence to ethical principles, deontological duties, and professional standards necessary for responsible conduct of scientific research. Early training on RI, especially for early-career researchers, could be useful to help develop good standards of conduct and prevent research misconduct (RM). The aim of this study is to assess the effectiveness of a training course on RI, by mapping the attitudes of early-career researchers on this topic through a questionnaire built upon the revised version of the Scientific Misconduct Questionnaire and administered to all participants at the beginning and at the end of the course. Results show that after the course, participants reporting a high understanding of the rules and procedures related to RM significantly increased (pre-course: 38.5%, post-course: 61.5%), together with the percentage of those reporting a lack of awareness on the extent of misconduct (pre-course: 46.2%, post-course: 69.2%), and of those who believe that the lack of research ethics consultation services strongly affects RM (pre-course: 15.4%, post-course: 61.5%). Early-career researchers agree on the importance to share with peers and superiors any ethical concern that may arise in research, and to create a work environment that fosters RI awareness. As a whole, results suggest the effectiveness of the course. Institutions should introduce RI training for early-career researchers, together with research methodology, integrity and ethics consultation services to support them. Senior scientists should promote RI into their research practices, and should stimulate engagement in peer-to-peer dialogue to develop good practices based on RI principles