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In this study, a methodology for assessing the thickness of titanium nitride (TiN) coatings by energy dispersive X-ray spectroscopy (EDS) in the scanning electron microscope is explored. A standardless method is applied, where the film thickness (th) is related to the microscope accelerating voltage (V0), the type of substrate and the ratio between the more intense peaks in the EDS spectrum, arising from both the substrate and the coating (afterwards called the I-ratio, IR). Three different substrates covered with TiN were studied, namely, silicon, glass, and stainless steel. Monte Carlo simulations enabled to state an analytic equation, which allows assessing the coating thickness as follows:th=thcr⋅exp[−βIR1/n]where IR = Iksubstrate/Ikcoating, thcr (critical thickness) is the largest coating thickness, which is assessable at a fixed V0, β is a multiplication factor, and n is an exponent, where thcr, β and n are assessable from V0 and substrate type. Interpolation via the equation presented, using reference thicknesses, allowed thickness predictions with around 80% of datapoints differing less than around 2% from the reference value. A procedure for detecting variations as low as 1.0% in coating thickness regarding the nominal thickness is presented.

The Spanish Ministry of Defense is currently attempting to reduce the amount of energy that is consumed by its military bases and has therefore raised concerns about how to make their facilities more energy efficient. To fulfill this objective, the Spanish army has developed various studies and projects, as well as a technical prescription sheet that defines the thermal transmittance values of the materials that are to be used to construct the different elements of the containers that make up the temporary housing units at Spanish military camps. Both governments and private entities have developed initiatives that are aimed at improving the energy efficiency of buildings, which are classified into two groups: those aimed at the development of mandatory building codes and those that are based on voluntary certification programs. The use of passive strategies is one of the key actions that is being implemented to achieve the NZEB category, as its first requirement is to be a “very low energy consumption building”. This paper compares the energy efficiency requirements of the tents and containers that are used in military camps and the energy-efficient design requirements that are demanded by the energy efficiency standards for buildings in the civil sector. Through this comparison, we determine how energy efficient the current living spaces in military camps are in order to define strategies that can be implemented to improve the design requirements of these living spaces so to reduce the consumption and operation logistics and to improve both operability and safety in military camp facilities.

This study analyzes future synergies between the Oil and Gas (O&G) and renewables sectors in a Danish context and explores how exploiting these synergies could lead to economic and environmental benefits. We review and highlight relevant technologies and related projects, and synthesize the state of the art in offshore energy system integration. All of these preliminary results serve as input data for a holistic energy system analysis in the Balmorel modeling framework. With a timeframe out to 2050 and model scope including all North Sea neighbouring countries, this analysis explores a total of nine future scenarios for the North Sea energy system. The main results include an immediate electrification of all operational Danish platforms by linking them to the shore and/or a planned Danish energy island. These measures result in cost and CO2 emissions savings compared to a BAU scenario of 72% and 85% respectively. When these platforms cease production, this is followed by the repurposing of the platforms into hydrogen generators with up to 3.6 GW of electrolysers and the development of up to 5.8 GW of floating wind. The generated hydrogen is assumed to power the future transport sector, and is delivered to shore in existing and/or new purpose-built pipelines. The contribution of the O&G sector to this hydrogen production amounts to around 19 TWh, which represents about 2% of total European hydrogen demand for transport in 2050. The levelized costs (LCOE) of producing this hydrogen in 2050 are around 4 €2020/kg H2, which is around twice those expected in similar studies. But this does not account for energy policies that may incentivize green hydrogen production in the future, which would serve to reduce this LCOE to a level that is more competitive with other sources., Advances in Applied Energy, 4, ISSN:2666-7924

Autonomous systems are expected to maintain a dependable operation without human intervention. They are intended to fulfill the mission for which they were deployed, properly handling the disturbances that may affect them. Underwater robots, such as the UX-1 mine explorer developed in the UNEXMIN project, are paradigmatic examples of this need. Underwater robots are affected by both external and internal disturbances that hamper their capability for autonomous operation. Long-term autonomy requires not only the capability of perceiving and properly acting in open environments but also a sufficient degree of robustness and resilience so as to maintain and recover the operational functionality of the system when disturbed by unexpected events. In this article, we analyze the operational conditions for autonomous underwater robots with a special emphasis on the UX-1 miner explorer. We then describe a knowledge-based self-awareness and metacontrol subsystem that enables the autonomous reconfiguration of the robot subsystems to keep mission-oriented capability. This resilience augmenting solution is based on the deep modeling of the functional architecture of the autonomous robot in combination with ontological reasoning to allow self-diagnosis and reconfiguration during operation. This mechanism can transparently use robot functional redundancy to ensure mission satisfaction, even in the presence of faults.

This contribution reports on an experimental polishing procedure, that is comprised of early grinding in Al2O3 slurries and late polishing in colloidal silica, which is used for preparing the nitrided region of a plasma nitrided austenitic stainless steel, for crystallographic analysis via electron backscatter diffraction (EBSD). The suitability of the polished surfaces for conducting EBSD characterization was assessed through an analysis of both the surface roughness (appraised by atomic force microscopy) and the quality of the Kikuchi diffraction patterns. We observed that as-nitrided virgin surfaces were not suitable for EBSD characterization, due to intense surface roughening, which was induced by the nitriding process itself. At the subsurface region, exposed by on-top mechanical polishing, the flatter nature of the polished surfaces allowed the acquisition of EBSD patterns with enough quality for microtexture analysis. A resolution of 100 nm in the total removed layer was attainable via careful control of the polishing parameters. Close parallelism between the polished and original surfaces was verified.

Resumen Introduccion La situacion de crisis generada por la COVID-19 y las medidas adoptadas han generado cambios sociales en las dinamicas normales de la poblacion general y en especial para los trabajadores de la salud, que se encuentran en atencion del paciente con infeccion sospechada o confirmada. Estudios recientes han detectado en ellos sintomas depresivos y ansiosos y sindrome de burnout, afecciones personales y sociales que alteran su capacidad de respuesta durante la emergencia sanitaria. El objetivo es generar recomendaciones de promocion y proteccion de la salud mental de los trabajadores y equipos de salud dispuestos como primera linea de atencion en la emergencia sanitaria por COVID-19. Metodos Se realizo una busqueda rapida de literatura en PubMed y Google Scholar, y un consenso de expertos iterativo y mediante consulta electronica, con 13 participantes de las areas de psicologia, psiquiatria y medicina; la gradacion de su fuerza y direccionalidad se realizo segun las normas internacionales del Joanna Briggs Institute. Resultados Se generaron 31 recomendaciones sobre el autocuidado del trabajador de la salud, el cuidado comunitario entre los equipos de salud, el cribado de signos de alarma en salud mental y para las instituciones sanitarias. Conclusiones Las actividades de promocion y proteccion en salud mental para el afrontamiento de la emergencia sanitaria generada por la COVID-19 en todo el mundo pueden abarcar acciones articuladas entre el trabajador, los equipos de salud y las instituciones sanitarias como parte de un cuidado integral, comunitario, corresponsable y sostenidas en el tiempo.

UNS S31603 stainless steel (SS) substrates were covered by reactive magnetron-sputtering with protective SS coatings of the same steel specification. A mechanical characterization study (through nano-, micro- and macro-hardness tests) of samples obtained under two different sputtering conditions and varying the N2 gas flow rate was carried out. This contribution aimed at appraising the effects of varying the nitrogen flow rate on hardness, elastic modulus, and susceptibility to indentation-induced crack formation of the coated SSs. Nitrogen-free samples displayed body-centered cubic (BCC) films with 9.0-9.4 GPa hardness and 203-206 GPa elastic modulus, while their susceptibility to indentation-induced cracking varied between superior and moderated among the two sets of sputtering conditions studied. Samples alloyed with 4-6 N at-% displayed a predominantly face-centered cubic (FCC) structure, 9.4 GPa hardness, 196-218 GPa elastic modulus, and superior resistance to crack formation. Samples with 11.5-22.0 N at-% were fully composed of the FCC structure, displayed 12.4-15.2 GPa hardness, 188-193 GPa elastic modulus, and moderated resistance to indentation-induced crack formation. Samples with 47.0 N at-% displayed FCC compound nitride structure, for which hardness and elastic modulus were 8.1 GPa and 139 GPa, respectively. These samples displayed low resistance to crack formation.

This paper presents a game theoretic decision making process for autonomous vehicles. Its goal is to provide a solution for a very challenging task: the merge manoeuvre in high traffic scenarios. Unlike previous approaches, the proposed solution does not rely on vehicle-to-vehicle communication or any specific coordination, moreover, it is capable of anticipating both the actions of other players and their reactions to the autonomous vehicle’s movements.

The constant growth of the population with mobility impairments has led to the development of several gait assistance devices. Among these, smart walkers have emerged to provide physical and cognitive interactions during rehabilitation and assistance therapies, by means of robotic and electronic technologies. In this sense, this paper presents the development and implementation of a human&ndash, robot&ndash, environment interface on a robotic platform that emulates a smart walker, the AGoRA Walker. The interface includes modules such as a navigation system, a human detection system, a safety rules system, a user interaction system, a social interaction system and a set of autonomous and shared control strategies. The interface was validated through several tests on healthy volunteers with no gait impairments. The platform performance and usability was assessed, finding natural and intuitive interaction over the implemented control strategies.

International audience; This paper presents a novel tool capable of collecting thermal signatures inside a building by using low-cost IR temperature sensors mounted on-board an aerial platform. The proposed system aims to facilitate the detection of heat loss inside buildings, which is a key aspect for improving energy efficiency in large commercial or industrial buildings. Current detection systems usually require manual labor as well as the use of expensive instrumentation. The proposed system on the other hand, relies on the use of a small unmanned aerial vehicle carrying low-cost thermopile IR sensors. Moreover, the system delivers a fast temperature sensing scheme and it provides coverage to inaccessible areas, thus overcoming the limitations of current mobile platforms which use ground robots. Different experiments were carried out in order to assess the behavior of the sensors as well as to validate the full system. Moreover, the hypothesis that thermopile IR sensors can be used to track temperature signature on-the-fly is validated experimentally with the use of the proposed system over different targets.

Flexible sector coupling of heat and electricity is a well-documented way of facilitating efficient and renewables-based energy systems. Heating is characterised by substitutable heat sources, where some facilitate flexibility and sector coupling, while others do not. Earlier studies indicate sector coupling hindrances from competing biomass-based heat sources. The scientific contribution of this study is an investigation of heat source substitution as a general route to sector coupling. We explore the impacts of constraining biomass use, applying the Danish heat sector as a case, to see impacts on indicators such as power-to-heat deployment. We do so by introducing taxes on biomass use, ban biomass boilers and entirely prohibit use of biomass. These constraints are modelled in the Balmorel model. The results show that system costs decrease along with biomass use. Power-to-heat use, CO2-emissions, tax- and electricity tariff revenue and end-user heat cost increase, in some cases substantially. It appears that a CO2 price signal is sufficient to obtain CO2-reductions, whereas other motivations, including increased electrification of the heating sector, may justify constraints on biomass use.

In this work, we present a decision-making system for automated vehicles driving in highway environments. The task is modeled as a Partially Observable Markov Decision Process, in which the physical states and intentions of surrounding traffic are uncertain. The problem is solved in an online fashion using Monte Carlo tree search. At each decision step, a search tree of beliefs is incrementally built and explored in order to find the current best action for the ego-vehicle. The beliefs represent the predicted state of the world as a response to the actions of the ego-vehicle and are updated using an interaction-and intention-aware probabilistic model. To estimate the long-term consequences of any action, we rely on a lightweight model-based prediction of the scene that assumes risk-averse behavior for all agents. We refer to the proposed decision-making approach as human-like, since it mimics the human abilities of anticipating the intentions of surrounding drivers and of considering the long-term consequences of their actions based on an approximate, common-sense, prediction of the scene. We evaluate the proposed approach in two different navigational tasks: lane change planning and longitudinal control. The results obtained demonstrate the ability of the proposed approach to make foresighted decisions and to leverage the uncertain intention estimations of surrounding drivers.

Robot cooperation is key in Search and Rescue (SaR) tasks. Frequently, these tasks take place in complex scenarios affected by different types of disasters, so an aerial viewpoint is useful for autonomous navigation or human tele-operation. In such cases, an Unmanned Aerial Vehicle (UAV) in cooperation with an Unmanned Ground Vehicle (UGV) can provide valuable insight into the area. To carry out its work successfully, such as multi-robot system requires the autonomous takeoff, tracking, and landing of the UAV on the moving UGV. Furthermore, it needs to be robust and capable of life-long operation. In this paper, we present an autonomous system that enables a UAV to take off autonomously from a moving landing platform, locate it using visual cues, follow it, and robustly land on it. The system relies on a finite state machine, which together with a novel re-localization module allows the system to operate robustly for extended periods of time and to recover from potential failed landing maneuvers. Two approaches for tracking and landing are developed, implemented, and tested. The first variant is based on a novel height-adaptive PID controller that uses the current position of the landing platform as the target. The second one combines this height-adaptive PID controller with a Kalman filter in order to predict the future positions of the platform and provide them as input to the PID controller. This facilitates tracking and, mainly, landing. Both the system as a whole and the re-localization module in particular have been tested extensively in a simulated environment (Gazebo). We also present a qualitative evaluation of the system on the real robotic platforms, demonstrating that our system can also be deployed on real robotic platforms. For the benefit of the community, we make our software open source., The research leading to these results received funding from RoboCity2030-DIH-CM, Madrid Robotics Digital Innovation Hub, S2018/NMT-4331, funded by “Programas de Actividades I+Den la Comunidad de Madrid” and cofunded by Structural Funds of the EU, and from the project DPI2014-56985-R (Robotic protection of critical infrastructures), financed by the Ministry of Economy and Competitiveness of the Government of Spain.

International audience; This article introduces an open source tool for simulating autonomous vehicles in complex, high traffic, scenarios. The proposed approach consists on creating an hybrid simulation, which fully integrates and synchronizes two well known simulators: a microscopic, multi-modal traffic simulator and a complex 3D simulator. The presented software tool allows to simulate an autonomous vehicle, including all its dynamics, sensors and control layers, in a scenario with a very high volume of traffic. The hybrid simulation creates a bi-directional integration, meaning that, in the 3D simulator, the ego-vehicle sees and interacts with the rest of the vehicles, and at the same time, in the traffic simulator, all additional vehicles detect and react to the actions of the ego-vehicle. Two interfaces, one for each simulator, where created to achieve the integration, they ensure the synchronization of the scenario, the state of all vehicles including the ego-vehicle, and the time. The capabilities of the hybrid simulation was tested with different models for the ego-vehicle and almost 300 additional vehicles in a complex merge scenario.

[Resumen] Este artículo presenta un nuevo enfoque para la interceptación de objetivos móviles en escenarios complejos y de gran tamaño. El planificador para interceptación se basa en el algoritmo Risk-RRT. Para mejorar el desempeño del algoritmo original se ha realizado la adaptación e integración de técnicas basadas en el Método de Fast Marching. Las modificaciones realizadas han permitido integrar de forma efectiva la información del entorno dentro del planificador y mejorar sus capacidades. La integración completa es capaz de planificar online y seguir la trayectoria, al mismo tiempo que ejecuta las funciones de interceptación y evasión de obstáculos.

[Resumen] Este trabajo presenta un sistema para la reconstrucción 3D de fondos acuáticos poco profundos utilizando medidas de un array de sensores de distancia tipo sonar acoplado a un robot submarino tipo torpedo. Se utiliza el simulador UWSim, específicamente desarrollado para misiones subacuáticas así como la arquitectura de control y navegación COLA2 adaptada al modelo de robot utilizado. Se ha desarrollado también una aplicación que controla la trayectoria del robot, de modo que se garantice la cobertura completa del área teniendo en cuenta los solapamientos necesarios para crear el mapa. A medida que el robot se desplaza por el escenario, las medidas del multibeam se integran para crear nubes de puntos parciales, que luego se agrupan para obtener el mapa 3D del fondo completo. Esta tarea de agrupación requiere de un proceso de corrección errores de localización relativa, para lo que se utiliza el algoritmo Iterative Closest Point. Este algoritmo requiere un complejo ajuste de filtros y configuraciones que para afinar el resultado final y conseguir una reconstrucción de buena calidad. Finalmente, el sistema se probó sobre varios escenarios y trayectorias diferentes, diseñados con el fin de evaluar la robustez del sistema y la calidad del mapa generado. Comunidad de Madrid; S2013/MIT-2748 Ministerio de Economía y Competitividad; DPI2014-56985-R

Success of teleoperation tasks for mobile robots in disaster scenarios depends largely on the skills of the operator. This article proposes a solution to facilitate this task with two UGVs working together in a master-slave structure. The slave robot is used as an external mobile camera, being able to select the best view for each situation, as you can do in video games. This method has several advantages for overcoming challenging situations that can be found in the mission and it has been tested in the Eurathlon Challenge with good results, completing the tasks in less time and with less stress for operators.

Muestras de acero inoxidable con estructura austenítica y contenido aproximado de nitrógeno de 0,9% en peso en solución sólida fueron sometidas a ensayos de cavitación vibratoria en agua destilada, con el fin de estudiar la evolución del desgaste erosivo por cavitación (EC) a escala del tamaño de grano (mesoescala). Las muestras fueron obtenidas por medio de nitruración gaseosa a alta temperatura (HTGN) del acero inoxidable dúplex UNS S31803, las cuales fueron caracterizadas por difracción de electrones retroproyectados (EBSD), a fin de obtener información de la orientación cristalina de los granos en la superficie a ser cavitada. La técnica de microscopía electrónica de barrido (SEM), fue usada para acompañar el proceso de desgaste para diferentes tiempos de ensayo. Como resultados de los ensayos de cavitación se determinó la pérdida de masa y se hizo un estudio secuencial de la apariencia superficial de las muestras para determinar los mecanismos de desgaste operantes en cada etapa. Los resultados fueron analizados a la luz de la caracterización cristalográfica previa. Para propósitos de comparación, fue usado el acero austenítico convencional UNS S30403. A partir de los resultados se observó que tanto la nucleación del daño como su evolución se dan de forma heterogénea a escala del tamaño de grano, resultado atribuido a la anisotropía en la deformación plástica. El carácter heterogéneo del daño por cavitación fue atribuido principalmente a las características de los límites de grano y a la microtextura dentro de los granos.Stainless steel samples with 100% austenitic microstructure and alloyed with 0.9 wt-% of nitrogen in solid solution were tested under vibratory cavitation experiments in distilled water to study the cavitation-erosion wear (EC) at grain size level (mesoscale). Fully austenitic samples were obtained by high temperature gas nitriding (HTGN) a commercially available dúplex stainless steel, UNS S31803. The samples were characterized by electron backscattering diffraction, EBSD to obtain the crystalline orientation of individual grains. In addition, mass loss measurements were obtained and surface damage evolution was analyzed by scanning electron microscopy (SEM) at different times of the test. These results were analyzed as a function of the prior crystallographic characterization. For comparison, a conventional austenitic stainless steel, UNS S30403, was also investigated. It was observed that both the nucleation and the growth of damage are heterogeneous at the grain-size scale due to mesoscale plasticity anisotropy, induced during the CE tests. The heterogeneous character of the cavitation damage is related to both the grain boundary character and the microtexture inside the grains.

Amostras do aço inoxidável UNS S31803, nitretadas em alta temperatura, com 0,9 % de nitrogênio em solução sólida foram submetidas a ensaios de cavitação vibratória em água destilada. As amostras foram, previamente, caracterizadas por meio de difração de elétrons retroespalhados, EBSD, num microscópio eletrônico de varredura (MEV). Posteriormente, durante os ensaios de cavitação, o dano superficial das amostras foi, periodicamente, avaliado por observação no MEV das superfícies desgastadas. O aço austenítico convencional UNS S30403 foi usado como material de comparação. Nas primeiras etapas dos ensaios de cavitação, ocorreu deformação plástica da superfície, que pôde ser caracterizada como altamente heterogênea na escala do tamanho de grão. Em etapas posteriores, ocorreu perda de massa por desprendimento de partículas de desgaste (debris), como conseqüência de fadiga de baixo ciclo. O início do dano ocorreu tanto no interior dos grãos como nos contornos de grão; os contornos de macla mostraram as regiões mais suscetíveis. Os grãos com planos (101) orientados aproximadamente paralelos à superfície das amostras apresentaram maior resistência ao desgaste que os grãos com outras orientações cristalográficas. A maior resistência ao desgaste dos grãos com textura (101) || superfície foi atribuída a uma menor tensão projetada para deformar, plasticamente, esses grãos. A diminuição da referida tensão se dá em função das tensões impostas na superfície cavitada pela implosão de bolhas de vapor.

Wrought material as well as physically simulated welding heat affected zone (HAZ) samples of an UNS S32304 duplex stainless steel were subjected to electrochemical corrosion tests and electron microscopy characterization. An impaired corrosion resistance of the HAZ microstructures compared to the wrought material microstructure was observed. Calphad-based numerical simulation of phase transformations and solute redistribution taking place during welding provided an explanation of the observed corrosion behavior. The poor corrosion resistance of the HAZ microstructures studied was mainly attributed to a decrease in corrosion resistance of ferritic grains after welding, which exhibited lower chromium content than ferritic grains in the wrought material.

Na década de 1970 Kaufman e Bernstein realizaram trabalho pioneiro sobre modelamento numérico da termodinâmica de sistemas multicomponentes e fundaram o grupo CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry), que tem como propósito promover a termodinâmica computacional e desenvolver programas computacionais para: (i) avaliar e validar dados experimentais (e teóricos) para incorporá-los às bases de dados auto-consistentes, (ii) representar as propriedades termodinâmicas de sistemas multicomponentes, (iii) modelar processos tecnológicos. Além de programas para modelamento termodinâmico, vários programas computacionais CALPHAD têm sido desenvolvidos, também, para calcular a cinética de transformações de fase controladas por difusão, os quais têm interfase com programas de calculo termodinâmico e com bases de dados de mobilidades atômicas. No presente trabalho relatam-se diferentes exemplos do uso do método CALPHAD para o modelamento matemático de diferentes processamentos térmicos e termoquímicos de aços, os quais correspondem a estudos de casos realizados no departamento de Engenharia Metalúrgica e de Materiais da Escola Politécnica da Universidade de São Paulo. Por meio de modelamento CALPHAD foi possível otimizar os parâmetros de processamento durante: a nitretação de aços de alta liga, o processamento térmico de aços TRIP, a produção de nitretos CrN e Cr2N a partir de pó de cromo, o tratamento térmico de solubilização de aços inoxidáveis e o tratamento térmico de decomposição de carbonetos em aços ferramenta.

Interstitially dissolved nitrogen improves the corrosion and wear resistance as well as the mechanical properties of stainless steels (SS) [1–5]. Production routes of High Nitrogen Stainless Steels (HNSS) by alloying, pressure metallurgy, powder metallurgy, and solid-state diffusion have been studied [6–10]. In the production route, which involves solid-state diffusion, the steel surface and near surface regions are alloyed with nitrogen through chemical, implantation, plasma, or laser techniques [9, 10]. Recently, a chemical solid-state nitrogen alloying technique was developed [10–14], consisting in annealing SS in a N2-containing gas atmosphere in the range 1273–1473 K. In this High Temperature Gas Nitriding treatment (HTGN), atomic nitrogen is absorbed at the surface of the steel and then diffuses into the near surface region. Case-depths from 0.5 to 2.0 mm and nitrogen contents in solid solution at the surface from 0.5–1.0 wt% can be obtained after 18 to 45 ks heat-treatments. HTGN has been successfully used to improve the surface properties of martensitic, austenitic, ferriticaustenitic and martensitic-ferritic SS [7, 10–13, 15]. Particularly, when ferritic-austenitic duplex stainless steels (DSS) are nitrided austenitic cases of higher wear and corrosion resistances are formed, on high strength DSS ferritic-austenitic cores. Due to both high temperatures and long nitriding times: (i) the austenitic cases grow forming coarse columnar grains [10–13], and (ii) the maximum attainable nitrogen content in precipitatefree cases corresponds to the nitrogen solubility limit at that temperature. The solubility limit in austenite, relative to nitride precipitation, increases with temperature; however the amount of ferrite in the dual-phase non-nitrided core increases with temperature too. Thus the optimum nitriding temperature for DSS is between 1423 and 1448 K. In the present work, a novel nitriding cycle that avoids formation of coarse grains in the austenitic case, inhibits nitride precipitation and leads to sharp textures is proposed. It consists on cycling the specimen between two different N2 partial pressures, PN2, (Fig. 1): a high-pressure stage (sorption stage) and a vacuum one (desorption stage). The high nitrogen pressure stage is a long term one where nitrogen is introduced in the specimen. It is followed by a short vacuum period (PN2 ∼ 0) where nitrogen desorption occurs and ferrite

El acero inoxidable UNS S31600 fue recubierto con películas de la aleación Ti6Al4V, por medio de la técnica pulverización catódica magnetrón rf. La superficie de los materiales obtenidos se sometió a ensayos de macroindentación, de acuerdo con el procedimiento VDI 3198, para caracterizar la adherencia película-sustrato. Se realizaron experimentos de depósito variando tanto la presión del gas al interior de la cámara de depósito como la potencia aplicada al blanco. La adherencia película-sustrato varío no monotónicamente con la presión y la potencia; la menor adherencia se observó para las presiones y las potencias intermedias. En términos generales se observó una excelente adherencia película-sustrato, la cual se atribuyó principalmente al carácter nanométrico de los cristalitos de las películas (diámetro promedio alrededor de 20 ± 10 nm), a su carácter monofásico y a su elevado grado de uniformidad tanto química como morfológica.

Planetary surface exploration is an appealing application of wireless sensor networks that has been investigated in recent years by the space community, including the European Space Agency. The idea is to deploy a number of self-organizing sensor nodes forming a wireless networked architecture to provide a distributed instrument for the study and exploration of a planetary body. To explore this concept, ESA has funded the research project RF Wireless for Planetary Exploration (RF-WIPE), carried out by GMV, SUPSI and UPM. The purpose of RF-WIPE was to simulate and prototype a wireless sensor network in order to assess the potential and limitations of the technology for the purposes of planetary exploration. In this paper, we illustrate the results of the work carried out within the context of RF-WIPE. Two test case scenarios have been investigated: a distributed sensor network-based instrument and networked planetary surface exploration. Each scenario is related to a particular network configuration. For such configurations, energy models and communication protocols have been developed, simulated, and validated both on laboratory tests and with outdoor field tests. Additionally, node deployment was investigated, and a deployment system based on a mobile robotics platform has been designed and tested., This work has been funded by the European Space Agency, under RFWIPE project N.30243/09 - GMV/AD, Postprint

Muestras de acero inoxidable con estructura austenitica y contenido aproximado de nitrogeno de 0,9% en peso en solucion solida fueron sometidas a ensayos de cavitacion vibratoria en agua destilada, con el fin de estudiar la evolucion del desgaste erosivo por cavitacion (EC) a escala del tamano de grano (mesoescala). Las muestras fueron obtenidas por medio de nitruracion gaseosa a alta temperatura (HTGN) del acero inoxidable duplex UNS S31803, las cuales fueron caracterizadas por difraccion de electrones retroproyectados (EBSD), a fin de obtener informacion de la orientacion cristalina de los granos en la superficie a ser cavitada. La tecnica de microscopia electronica de barrido (SEM), fue usada para acompanar el proceso de desgaste para diferentes tiempos de ensayo. Como resultados de los ensayos de cavitacion se determino la perdida de masa y se hizo un estudio secuencial de la apariencia superficial de las muestras para determinar los mecanismos de desgaste operantes en cada etapa. Los resultados fueron analizados a la luz de la caracterizacion cristalografica previa. Para propositos de comparacion, fue usado el acero austenitico convencional UNS S30403. A partir de los resultados se observo que tanto la nucleacion del dano como su evolucion se dan de forma heterogenea a escala del tamano de grano, resultado atribuido a la anisotropia en la deformacion plastica. El caracter heterogeneo del dano por cavitacion fue atribuido principalmente a las caracteristicas de los limites de grano y a la microtextura dentro de los granos. Stainless steel samples with 100% austenitic microstructure and alloyed with 0.9 wt-% of nitrogen in solid solution were tested under vibratory cavitation experiments in distilled water to study the cavitation-erosion wear (EC) at grain size level (mesoscale). Fully austenitic samples were obtained by high temperature gas nitriding (HTGN) a commercially available duplex stainless steel, UNS S31803. The samples were characterized by electron backscattering diffraction, EBSD to obtain the crystalline orientation of individual grains. In addition, mass loss measurements were obtained and surface damage evolution was analyzed by scanning electron microscopy (SEM) at different times of the test. These results were analyzed as a function of the prior crystallographic characterization. For comparison, a conventional austenitic stainless steel, UNS S30403, was also investigated. It was observed that both the nucleation and the growth of damage are heterogeneous at the grain-size scale due to mesoscale plasticity anisotropy, induced during the CE tests. The heterogeneous character of the cavitation damage is related to both the grain boundary character and the microtexture inside the grains.

Os aços inoxidáveis de alto teor de nitrogênio constituem hoje uma classe promissora de materiais de engenharia. Quando se adiciona nitrogênio aos aços austeníticos, consegue-se aumentar, simultaneamente, a vida em fadiga, a resistência mecânica, a resistência ao desgaste e à corrosão. Nesse trabalho, estudam-se a resistência ao desgaste e a usinabilidade de um aço inoxidável austenítico UNS S30403 nitretado em alta temperatura. A nitretação gasosa em alta temperatura (1200ºC) em atmosferas (N2+Ar) foi realizada para obter amostras com teores crescentes de nitrogênio na superfície, desde 0,05 até aproximadamente 0,45% em peso. Os ensaios de esclerometria foram realizados em um pêndulo instrumentado de um único passe, com possibilidade de medir as forças normais e tangenciais durante o ensaio. A energia específica absorvida foi calculada através da relação entre a energia absorvida no ensaio e a perda de massa observada no ensaio. Observou-se que o aumento do teor de nitrogênio causou um aumento da energia específica absorvida. Os resultados dos ensaios foram analisados levando em consideração o comportamento da curva tensão deformação desses aços, inferida a partir de ensaios de indentação instrumentada, e da energia absorvida em ensaios de impacto Charpy. O aumento da resistência ao risco e a diminuição da usinabilidade devida à adição de nitrogênio foram atribuídos ao forte efeito endurecedor do nitrogênio em solução sólida, sem afetar, significativamente, a taxa de encruamento e a tenacidade. High nitrogen stainless steels (HNSS) are being considered a new promising class of engineering materials. When nitrogen is added to austenitic steels it can simultaneously improve fatigue life, strength and wear and localized corrosion resistance. In this work, a single pass pendulum scratch test was used to study the effect of nitrogen on the scratch resistance and on the machinability of an UNS S30403 austenitic stainless steel. Samples with increasing nitrogen contents at the surface were obtained through high temperature gas nitriding. The thermochemical treatments were performed at 1473 K in (N2+Ar) gas atmospheres for 36.0 ks, obtaining fully austenitic cases (surface nitrogen contents up to 0.5 wt%) ca. 1.5 mm in depth. The scratch tests were performed in a single-pass pendulum, equipped with strain gages to measure normal and tangential forces during scratching. The specific absorbed energy was calculated as the ratio between the measured absorbed energy and the amount of mass removed from the specimen. An increase of the specific absorbed energy with increasing nitrogen content was observed. The results of the scratch tests were analyzed taking into account the stress-strain behavior during depth sensing indentation tests and the energy absorbed during Charpy impact tests. The improvement in scratch resistance due to nitrogen alloying was attributed to the strong hardening effect of nitrogen in solid solution, which does not affect significantly foundry hardening and toughness. A comparison between the scratch resistance and the pitting-erosion resistance, measured in previous work, was made too.

This paper presents a pedestrian trajectory prediction technique. Its mail novelty is that it does not require any previous observation or knowledge of pedestrian trajectories, thus making it useful for autonomous surveillance applications. The prediction requires only a set of possible goals, a map of the scenario and the initial position of the pedestrian. Then, it uses two different path planing algorithms to find the possible routes and transforms the similarity between observed and planned routes into probabilities. Finally, it applies a motion model to obtain a time-stamped predicted trajectory. The system has been used in combination with a pedestrian detection and tracking system for real-world tests as well as a simulation software for a large number of executions.