Reducing Communication Delay Variability for a Group of Robots

A novel architecture is presented for reducing communication delay variability for a group of robots. This architecture relies on using three components: a microprocessor architecture that allows deterministic real-time tasks; an event-based communication protocol in which nodes transmit in a TDMA fashion, without the need of global clock synchronization techniques; and a novel communication scheme that enables deterministic communications by allowing senders to transmit without regard for the state of the medium or coordination with other senders, and receivers can tease apart messages sent simultaneously with a high probability of success. This approach compared to others, allows simultaneous communications without regard for the state of the transmission medium, it allows deterministic communications, and it enables ordered communications that can be a applied in a team of robots. Simulations and experimental results are also included

Application of laser in seam welding of dissimilar steel to aluminium joints for thick structural components

Laser welding-brazing technique, using a continuous wave (CW) fibre laser with 8000 W of maximum power, was applied in conduction mode to join 2 mm thick steel (XF350) to 6 mm thick aluminium (AA5083-H22), in a lap joint configuration with steel on the top. The steel surface was irradiated by the laser and the heat was conducted through the steel plate to the steel-aluminium interface, where the aluminium melts and wets the steel surface. The welded samples were defect free and the weld micrographs revealed presence of a brittle intermetallic compounds (IMC) layer resulting from reaction of Fe and Al atoms. Energy Dispersive Spectroscopy (EDS) analysis indicated the stoichiometry of the IMC as Fe2Al5 and FeAl3, the former with maximum microhardness measured of 1145 HV 0.025/10. The IMC layer thickness varied between 4 to 21 μm depending upon the laser processing parameters. The IMC layer showed an exponential growth pattern with the applied specific point energy (Esp) at a constant power density (PD). Higher PD values accelerate the IMC layer growth. The mechanical shear strength showed a narrow band of variation in all the samples (with the maximum value registered at 31.3 kN), with a marginal increase in the applied Esp. This could be explained by the fact that increasing the Esp results into an increase in the wetting and thereby the bonded area in the steel-aluminium interface

The mechanism of activation of the adenovirus type 2 protease

The adenovirus codes for a protease which is essential for virion infectivity. This protease requires the presence of a peptide cofactor in order to develop optimal activity. This peptide, GVQSLBCRRRCF, originates from the C-terminal of a viral protein, pVI, and some evidence regarding its specificity came from observations showing that neither of the peptides GVQSLKRRRAF or KRRRCF was able to activate the protease, indicating that both the cysteine and the N-terminal were important in the activation process. However, the mechanism by which the peptide activates the protease has never been elucidated. In this project, several factors contributing to the activation mechanism of the human adenovirus type 2 protease were studied, such as the peptide N-terminal length and composition, the environment close to the cysteine and the distance between the N-terminal and the cysteine, in view of assessing the relevance of each of these parameters in the activation process and proposing a mechanism of activation. Based on the above studies, attempts of protease inhibition were also performed based on the activation process rather than on the blocking of the active site, and the relevance of these results was related with the proposed activation mechanism. An attempt to clone an avian adenovirus protease was also performed, in order to try and compare the activation processes between the two proteases

Performance Evaluation Between HarperDB, Mongo DB and PostgreSQL

Several modern-day problems, like information overload and big data, need to deal with large amounts of data. As such, to meet the application requirements, for instance, performance and consistency, more and more systems are adapting to the specificities. The existing Relational Database Management System (RDBMS)’s the processing of massive data has become an issue because these databases do not deal with a massive amount of data. NoSQL is a database management system that makes processing massive and/or unstructured data easier because it uses key-value to store the data, collections or document stores instead of tables. Many companies today tend to start a project using NoSQL. However, HarperDB aims to produce a relational and nonrelational DBMS, allowing developers to choose between different solutions. This paper aims to show the most relevant differences between HarperDB, MongoDB and PostgreSQL and compare their performances. Preliminary results show that PostgreSQL performs better with structured data, but HarperDB can integrate NoSQL and SQL, which can be a significant advantage to HarperDB compared to the other solutions.info:eu-repo/semantics/publishedVersio

Role of Room Temperature Sputtered High Conductive and High Transparent Indium Zinc Oxide Film Contacts on the Performance of Orange, Green, and Blue Organic Light Emitting Diodes

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Towards a systematic threat modeling approach for cyber-physical systems

Abstract—Cyber-Physical Systems (CPS) are systems with seamless integration of physical, computational and networking components. These systems can potentially have an impact on the physical components, hence it is critical to safeguard them against a wide range of attacks. In this paper, it is argued that an effective approach to achieve this goal is to systematically identify the potential threats at the design phase of building such systems, commonly achieved via threat modeling. In this context, a tool to perform systematic analysis of threat modeling for CPS is proposed. A real-world wireless railway temperature monitoring system is used as a case study to validate the proposed approach. The threats identified in the system are subsequently mitigated using National Institute of Standards and Technology (NIST) standards

Selection of processing parameters in laser microwelding. Part 1: Continuous wave (CW) mode

A phenomenological model which specifies the penetration depth and width of the fusion zone in laser microjoining can be a very useful tool in achieving the required welding parameters for a desired application. In this study the power factor model, previously established and validated in macrowelding, has been tested in fibre laser microwelding, enabling achievement of a particular weld independently of a laser system. Differ-ent weld profiles in aluminium and stainless steel were correlated with various combinations of parameters for a wide range of beam diameters. It has been shown that the same penetration depth can be achieved with different weld profiles. A similar trend, as previously found in macrow-elding, has been confirmed in microwelding. It was demonstrated that the depth of penetration can be kept constant independently of the laser sys-tem until certain limit of beam size

Evaluation of water resources in a high-mountain basin in Serra da Estrela, Central Portugal, using a semi-distributed hydrological model

High-mountain basins provide a source of valuable water resources. This paper presents hydrological models for the evaluation of water resources in the highmountain Zezere river basin in Serra da Estrela, Central Portugal. Models are solved with VISUAL BALAN v2.0, a code which performs daily water balances in the root zone, the unsaturated zone and the aquifer and requires a small number of parameters. A lumped hydrological model failsto fit measured stream flows. Its limitations are overcome by considering the dependence of the temperature and precipitation data with elevation and the spatial variability in hydrogeomorphological variables with nine sub-basins of uniform parameters. Model parameters are calibrated by fitting stream flow measurements in the Zezere river. Computed stream flows are highly sensitive to soil thickness, whereas computed groundwater recharge is most sensitive to the interflow and percolation recession coefficients. Interflow is the main component of total runoff, ranging from 41 to 55% of annual precipitation. High interflows are favored by the steep relief of the basin, by the presence of a high permeability soil overlying the fractured low permeability granitic bedrock and by the extensive subhorizontal fracturing at shallow depths. Mean annual groundwater recharge ranges from 11 to 15% of annual precipitation. It has a significant uncertainty due to uncertainties in soil parameters. This methodology proves to be useful to handle the research difficulties regarding a complex mountain basin in a context of data scarcity.info:eu-repo/semantics/publishedVersio

The re-organization of action in golf putting under different task constraints

Background: The behaviours of golfers could be interpreted as emergent, resulting from the cyclical relations of perception-action couplings established under the interacting constraints of competitive performance environments. Underpinned by an ecological dynamics approach, the aim of this study was to investigate how a simple adaptation of task constraints constrained the (re)organization of putting actions in skilled golfers. Methods: Ten skilled golfers, male and right-handed (42.6 ± 14.4 years old) (average handicap of 2.3 ± 1.7) were investigated when putting at different distances from the hole. Results: Our results have revealed how the coupling of perception and action captures the mutual relationship that emerges between a performance environment and each golfer’s abilities, during task performance. In this sense, the manipulation of distance constraints selectively constrained movement organization variables in specific ways. As distance to the hole increased, there was a clear increment in backswing, downswing and follow-through amplitude, speed of putter impact on the ball and maximum acceleration of the putting movement. Moreover, heart rate (HR) decreased with distance to the hole, which may have indicated that a golfer was adapting to increasing distance constraints, or that a greater distance from the hole may require a greater attentional focus. Conclusions: Underpinned by an ecological dynamics approach, these and other findings in our study suggested some regularities in the behaviour of golfers when environmental constraints (e.g., distance) are manipulated. Thus, golfers’ behaviours can be interpreted as an emergent process resulting from the perception-action coupling relations established during practice and performance

Conceptual Representations for Computational Concept Creation

Computational creativity seeks to understand computational mechanisms that can be characterized as creative. The creation of new concepts is a central challenge for any creative system. In this article, we outline different approaches to computational concept creation and then review conceptual representations relevant to concept creation, and therefore to computational creativity. The conceptual representations are organized in accordance with two important perspectives on the distinctions between them. One distinction is between symbolic, spatial and connectionist representations. The other is between descriptive and procedural representations. Additionally, conceptual representations used in particular creative domains, such as language, music, image and emotion, are reviewed separately. For every representation reviewed, we cover the inference it affords, the computational means of building it, and its application in concept creation.Peer reviewe