Automated construction activity monitoring system

Building activities are inadequately monitored during construction projects when attempting to satisfy the need for information, especially in those cases of unforeseen events and conditions on-site. Many IT-supported methods have been introduced, but so far none has been able to deliver satisfactory and reliable information. This paper presents a combined method, consisting of three components: an automated activity tracking subsystem based on image recognition, an automated material tracking subsystem, and a mobile computing supported communication environment. All subsystems are based on the same 4D model of a building.     

Immunity of electronic and transport properties of phosphorene nanoribbons to edge defects

We present an extensive study of the electronic properties and carrier transport in phosphorene nanoribbons (PNRs) with edge defects by using rigorous atomistic quantum transport simulations. This study reports on the size- and defect-dependent scaling laws governing the transport gap, and the mean free path and carrier mobility in the PNRs of interest for future nanoelectronics applications. Our results indicate that PNRs with armchair edges (aPNRs) are more immune to defects than zig-zag PNRs (zPNRs), while both PNR types exhibit superior immunity to defects relative to graphene nanoribbons (GNRs). An investigation of the mean free path demonstrated that even in the case of a low defect density the transport in PNRs is diffusive, and the carrier mobility remains a meaningful transport parameter even in ultra-small PNRs. We found that the electron–hole mobility asymmetry (present in large-area phosphorene) is retained only in zPNRs for W > 4 nm, while in other cases the asymmetry is smoothed out by edge defect scattering. Furthermore, we showed that aPNRs outperform both zPNRs and GNRs in terms of carrier mobility, and that PNRs generally offer a superior mobility-bandgap trade-off, relative to GNRs and monolayer MoS₂. This work identifies PNRs as a promising material for the extremely scaled transistor channels in future post-silicon electronic technology, and presents a persuasive argument for experimental work on nanostructured phosphorene.

Open image in new window

     

Extending the Colloidal Transition Metal Dichalcogenide Library to ReS2 Nanosheets for Application in Gas Sensing and Electrocatalysis

Among the large family of transition metal dichalcogenides, recently ReS₂ has stood out due to its nearly layer‐independent optoelectronic and physicochemical properties related to its 1T distorted octahedral structure. This structure leads to strong in‐plane anisotropy, and the presence of active sites at its surface makes ReS₂ interesting for gas sensing and catalysts applications. However, current fabrication methods use chemical or physical vapor deposition (CVD or PVD) processes that are costly, time‐consuming and complex, therefore limiting its large‐scale production and exploitation. To address this issue, a colloidal synthesis approach is developed, which allows the production of ReS₂ at temperatures below 360 °C and with reaction times shorter than 2h. By combining the solution‐based synthesis with surface functionalization strategies, the feasibility of colloidal ReS₂ nanosheet films for sensing different gases is demonstrated with highly competitive performance in comparison with devices built with CVD‐grown ReS₂ and MoS₂. In addition, the integration of the ReS₂ nanosheet films in assemblies together with carbon nanotubes allows to fabricate electrodes for electrocatalysis for H₂ production in both acid and alkaline conditions. Results from proof‐of‐principle devices show an electrocatalytic overpotential competitive with devices based on ReS₂ produced by CVD, and even with MoS₂, WS₂, and MoSe₂ electrocatalysts.     

Bootstrapping MDE development from ROS manual code: Part 2—Model generation and leveraging models at runtime

Software and Systems Modeling - Model-driven engineering (MDE) addresses central aspects of robotics software development. MDE could enable domain experts to leverage the expressiveness of models,...     

An algebraic approach for modelling organisation, roles and contexts in MAS

Governing the ever growing complexity of artificial systems on the one hand requires a number of expressive abstractions and different levels of interpretation, on the other hand suggests the adoption of formal / mathematical tools to (at least partially) model and predict the system behaviour. By adopting agent-oriented abstractions as the starting point, we argue that organisation, coordination and security all insist on the same conceptual space – that is, static / dynamic relations / interactions among agents –, which also represents one of the main sources of complexity for MAS, and for artificial systems in general, as well.The notion of ACC (agent coordination context) is used in this paper as the unifying core abstraction of a framework that encompasses all such issues, promoting the integration of organisation, coordination, and security. Such a framework, called RBAC-MAS, is expressed through a process algebraic model which integrates the classic organisational issues of role-based models (like RBAC) and the more recent works on interaction and coordination in MAS.     

Formal Specification and Enactment of Security Policies through Agent Coordination Contexts

Our research moves from three fundamental considerations that concern the modelling and engineering of complex systems. First, organization, coordination and security are strictly related issues that should be modelled in a uniform and coherent framework. Second, models, technologies and methodologies should come hand in hand, so that abstractions used in the analysis and design stages should be still “alive and kicking” at development and execution time. Third, the general non-formalisability of complex systems should not prevent us from using formal tools whenever useful, such as in proving or ensuring properties of limited but meaningful portions of a system.By focussing on multi-agent systems, we discuss the notion of Agent Coordination Context (ACC) as an abstraction that (i) works as an organization and security abstraction, (ii) integrates well with abstractions provided by coordination infrastructures, and (iii) covers the engineering process from design to deployment. In particular, in this paper we study the syntax and semantics of a language for ACCs specification, exploiting typical process algebra techniques. Accordingly, we show that process algebras are a suitable tool for both specification and enactment of security and coordination policies through ACCs.     

Practical Olefin Metathesis in Protic Media under an Air Atmosphere

The discovery that efficient olefin metathesis reactions involving previously challenging terminal olefin substrates are possible using novel and readily available catalyst systems in non‐distilled, non‐degassed protic media in air is reported.     

Numerical analyses for the prediction of the splitting strength of beams loaded perpendicular-to-grain by dowel-type connections

The paper presents a parametric numerical study on the splitting strength of timber beams loaded perpendicular-to-grain by dowel-type connections. The main aims of the numerical investigations are: (1) find out the influence of main connection parameters on the splitting strength of beams; (2) compare the above evaluated influences with the ones proposed by the first author in a recently developed semi-empirical prediction formula. The first part of the paper presents the mentioned new semi-empirical prediction formula which has been developed by means of a survey on experimental data from literature. The formula is presented in its main aspects and later its prediction capability is discussed and compared with the ones of formulae embodied in new European and German design codes for timber structures. The second part of the paper reports the main results of parametric numerical analyses carried out in the framework of Linear Elastic Fracture Mechanics (LEFM) by means of a crack propagation approach. The analyses are performed on beams of different size loaded at mid-span by both single and multiple dowel connections. The main investigated parameters are the connection width (l _r), the connection depth (h _m), and the number of rows of fasteners (n). They are analysed for different beam heights (h) and for different distances of the most distant row of fasteners from beam loaded edge (h _e). The numerical results are compared with available experimental test data and with the relationships embodied in the above-mentioned semi-empirical prediction formula.

---

Résumé L’article présente les résultats d’une étude numérique paramétrique qui analyse la résistance à la fissuration de poutres en bois chargées perpendiculairement aux fibres de connexions, avec des connecteurs cylindriques. Le but principal de cette étude numérique est: (1) déterminer l’influence des paramètres principaux des connexions sur la résistance à fissuration des poutres; (2) comparer les résultats obtenus avec les résultats proposés par Ballerini dans une formule récente de prédiction semi-empirique. La première partie de l’article présente la formula citée de prédiction semi-empirique développée sur base d’une analyse des données expérimentales disponibles dans le texte. La formule est illustrée dans ses aspects principaux et par la suite sa capacité prévisible est comparée avec celle des formules adoptées par les récentes normes européennes et allemandes pour les structures en bois. La seconde partie de l’article reprend les principaux résultats de l’analyse numérique paramétrique développés dans le domaine de la Mécanique de la Fracture Linéaire Elastique (LEFM) à l’aide d’analyses avec propagation de fissure. Les analyses concernent des poutres de différentes dimensions chargées en ligne de connexions avec un ou plusieurs connecteurs cylindriques. Les paramètres principaux étudiés sont la largeur (l_r), la hauteur (h_m) et le nombre de lignes des connecteurs (n) de la connexion. Les analyses concernaient des poutres de différentes hauteurs (h) et placés à différentes distances par rapport au bord des poutres de la ligne des connecteurs plus éloignée (h_e). Les résultats numériques sont comparés avec les données expérimentales disponibles et les études prévues par la formule citée de prédiction semi-empirique.