Sensor development and integration for robotized laser welding

Laser welding requires fast and accurate positioning of the laser beam over the seam trajectory. The task of accurate positioning of the laser tools is performed by robotic systems. It is therefore necessary to teach the robot the path it has to follow. Seam teaching is implemented in several ways: Offline Programming, Manual Point-to-point, Sensor Guided. The first two processes are time consuming; the second requires constant human interaction, whereas the last one is fast and fully automated.\ud The most commonly used seam detection sensors are based on optical triangulation with a single structured light line. Such sensors impose restrictions on the laser tool orientation in relation to the seam trajectory. The shape of the seam trajectory in combination with the required speed, can force the robot into positioning errors due to robot dynamics. Furthermore, closed looped seam trajectories such as circles or rectangles are not possible to be taught with such sensors. \ud A solution to these problems is given by the seam detection sensor of the integrated laser welding head. The developed perimetric sensor allows the detection and following of seam trajectories without restrictions on the relative position of the welding head. This reduces positioning errors due robot dynamics and allows looped seam trajectories. \ud The developed integrated laser welding head fulfills two additional sensing functionalities: weld inspection and process monitor. The weld inspection sensor measures the weld surface properties and provides quality estimation according to ISO13919. The process monitor sensor allows the detection of the keyhole formation in full penetration welding. \ud The integration of these sensors into one compact laser welding head required the fusion of their optical paths. Automated calibration procedures have been developed for the system’s integration with robots. Finally, a user friendly sensor software application has been developed that allows access and overview of all the sensors’ processes and handles all required data communications

Sensor integration for robotic laser welding processes

The use of robotic laser welding is increasing among industrial applications, because of its ability to weld objects in three dimensions. Robotic laser welding involves three sub-processes: seam detection and tracking, welding process control, and weld seam inspection. Usually, for each sub-process, a separate sensory system is required. The use of separate sensory systems leads to heavy and bulky tools, in contrast to compact and light sensory systems that are needed to reach sufficient accuracy and accessibility. In the solution presented in this paper all three subprocesses are integrated in one compact multipurpose welding head. This multi-purpose tool is under development and consists of a laser welding head, with integrated sensors for seam detection and inspection, while also carrying interfaces for process control. It can provide the relative position of the tool and the work piece in three-dimensional space. Additionally, it can cope with the occurrence of sharp corners along a three-dimensional weld path, which are difficult to detect and weld with conventional equipment due to measurement errors and robot dynamics. In this paper the process of seam detection will be mainly elaborated

Integrated sensors for robotic laser welding

A welding head is under development with integrated sensory systems for robotic laser welding applications. Robotic laser welding requires sensory systems that are capable to accurately guide the welding head over a seam in three-dimensional space and provide information about the welding process as well as the quality of the welding result. In this paper the focus is on seam tracking. It is difficult to measure three-dimensional parameters of a ream during a robotic laser welding task, especially when sharp corners are present. The proposed sensory system is capable to provide the three dimensional parameters of a seam in one measurement and guide robots over sharp corners

Simulating molecular docking with haptics

Intermolecular binding underlies various metabolic and regulatory processes of the cell, and the therapeutic and pharmacological properties of drugs. Molecular docking systems model and simulate these interactions in silico and allow the study of the binding process. In molecular docking, haptics enables the user to sense the interaction forces and intervene cognitively in the docking process. Haptics-assisted docking systems provide an immersive virtual docking environment where the user can interact with the molecules, feel the interaction forces using their sense of touch, identify visually the binding site, and guide the molecules to their binding pose. Despite a forty-year research e�ort however, the docking community has been slow to adopt this technology. Proprietary, unreleased software, expensive haptic hardware and limits on processing power are the main reasons for this. Another signi�cant factor is the size of the molecules simulated, limited to small molecules. The focus of the research described in this thesis is the development of an interactive haptics-assisted docking application that addresses the above issues, and enables the rigid docking of very large biomolecules and the study of the underlying interactions. Novel methods for computing the interaction forces of binding on the CPU and GPU, in real-time, have been developed. The force calculation methods proposed here overcome several computational limitations of previous approaches, such as precomputed force grids, and could potentially be used to model molecular exibility at haptic refresh rates. Methods for force scaling, multipoint collision response, and haptic navigation are also reported that address newfound issues, particular to the interactive docking of large systems, e.g. force stability at molecular collision. The i ii result is a haptics-assisted docking application, Haptimol RD, that runs on relatively inexpensive consumer level hardware, (i.e. there is no need for specialized/proprietary hardware)

Classroom observation in second language classrooms : bridging the gap between theory and practice for pre-service and in-service teachers of Greek as an L2

This paper is a qualitative study in the framework of a broader project (LETEGR2) that aims to shed light on the way classroom-based observation might contribute to bridging the gap between teaching theory and practice and assisting teacher education. It draws on data derived from pre-service (n=15) and in-service teachers (n=6) who applied the LETEGR2 Classroom Observation protocol in second language classrooms in Greece. Both groups of data are presented according to the observation stages (pre- and post-) in which they have been collected. They are discussed as pre- and in-service teachers' "voices" in terms of the main issues they bring to the fore in relation to L2 learners' profiles, the teaching process and teachers' practices. An attempt is made to link both group of participants' observed behaviours and events to underlying theoretical concepts for second language learning and teaching.La investigació següent és un estudi qualitatiu que forma part d'un projecte més ampli anomenat LETEGR2. L'objectiu d'aquesta investigació és explicar com l'observació a l'aula pot contribuir a disminuir la bretxa entre els coneixements teòrics, la pràctica docent i la formació del professorat. Està basada en dades recollides de professors en pràctiques (n=15) i de professors en actiu (n=6) que van seguir el protocol d'Observació d'Aula del LETEGR2 en aules on s'ensenya grec com a segona llengua estrangera a Grècia. Totes les dades recollides es presenten seguint les diferents etapes d'observació en les quals han estat recollides (pre- i post-). La discussió de les dades es presenta a través de les veus dels dos grups de participants en relació als perfils dels alumnes d'una L2, el procés d'ensenyament i les pràctiques dels docents. S'intenta establir un vincle entre els comportaments i accions observades a cada grup de participants i els conceptes teòrics subjacents en el camp de l'ensenyament i aprenentatge d'una segona llengua.La presente investigación es un estudio cualitativo que forma parte de un proyecto más amplio llamado LETEGR2. El objetivo de esta investigación es elucidar cómo la observación en el aula puede contribuir a disminuir la brecha entre los conocimientos teóricos, la práctica docente y la formación del profesorado. Está basada en datos obtenidos de profesores en prácticas (n=15) y profesores en activo (n=6) que siguieron el protocolo de Observación de Aula del LETEGR2 en aulas de enseñanza de griego como segunda lengua en Grecia. Todos los datos generados se presentan teniendo en cuenta las diferentes etapas de observación en las que se han recogido (pre- y post-). La discusión de los datos se presenta a través de las voces de los dos grupos de participantes en referencia a los perfiles de los alumnos de una L2, el proceso de enseñanza y las prácticas de los docentes. Se intenta establecer un vínculo entre los comportamientos y las acciones observadas en ambos grupos de participantes y los conceptos teóricos subyacentes en el campo de la enseñanza y aprendizaje de una segunda lengua

Combined Approaches in Sialolithiasis of Major Salivary Glands

Combined (endoscopic-transcutaneous) techniques are an effective treatment for large and/or impacted stones of the major salivary glands. This approach results in high rates of symptom improvement and gland preservation. The complication rates are relatively low, further supporting the use of these techniques as an additional tool between the classic sialendoscopy and the external classic procedures of gland removal. In this chapter, we describe the combined approach for the parotid gland and the submandibular gland and finally, the retrograde sialendoscopy through the surgical field of an open approach

Sustainable supply chain management in the digitalisation era: The impact of Automated Guided Vehicles

Internationalization of markets and climate change introduce multifaceted challenges for modern supply chain (SC) management in the today's digitalisation era. On the other hand, Automated Guided Vehicle (AGV) systems have reached an age of maturity that allows for their utilization towards tackling dynamic market conditions and aligning SC management focus with sustainability considerations. However, extant research only myopically tackles the sustainability potential of AGVs, focusing more on addressing network optimization problems and less on developing integrated and systematic methodological approaches for promoting economic, environmental and social sustainability. To that end, the present study provides a critical taxonomy of key decisions for facilitating the adoption of AGV systems into SC design and planning, as these are mapped on the relevant strategic, tactical and operational levels of the natural hierarchy. We then propose the Sustainable Supply Chain Cube (S2C2), a conceptual tool that integrates sustainable SC management with the proposed hierarchical decision-making framework for AGVs. Market opportunities and the potential of integrating AGVs into a SC context with the use of the S2C2 tool are further discussed

The emerging role of water footprint in supply chain management: A critical literature synthesis and a hierarchical decision-making framework

Freshwater overexploitation and scarcity have led to extensive shifts in demand patterns for water-friendly products. As several agricultural and industrial activities are closely intertwined with water consumption, the availability of sufficient freshwater resources constitutes a significant precondition for covering global consumer needs. In this context, the design and management of sustainable supply chains in terms of freshwater resources' preservation have emerged as major challenges in the corporate agenda. As such, the concept of water footprint as a key performance indicator of freshwater utilization has been introduced at national, corporate and product levels. In this manuscript, we first provide a critical literature synthesis concerning product water footprint assessment in order to map the state-of-the-art research related to freshwater consumption and pollution in the agricultural and industrial sectors. Our analysis demonstrates that although water footprint assessment is a rapidly evolving research field, scientific publications focusing on a holistic approach concerning freshwater exploitation at a supply chain extent are rather limited. The findings further verify that the agrifood sector dominates global water use. In this respect, we analyse both corporate and academic literature in order to identify emerging issues on freshwater resources' management for agrifood products. Finally, we propose a first-effort hierarchical decision-making framework that includes water footprint mitigation policies for agrifood supply chains in order to support all stakeholders in developing a comprehensive water stewardship strategy.Public Benefit Foundation Alexander S. Onassis, European Community 7th Framework Programme (FP7-REGPOT- 2012-2013-1) GREEN-AgriChains project (Grant ID: 316167

Design of sustainable supply chains for the agrifood sector: a holistic research framework

Agrifood sector is one of the most important economic and political areas within the European Union, with key implications for sustainability such as the fulfillment of human needs, the support of employment and economic growth, and its impact on the natural environment.  Growing environmental, social and ethical concerns and increased awareness of the impacts of the agrifood sector have led to increased pressure by all involved supply chain stakeholders, while at the same time the European Union has undertaken a number of relevant regulatory interventions.  This paper aims to present a methodological framework for the design of green supply chains for the agrifood sector.  The framework aims towards the optimization of the agrifood supply chain design, planning and operations through the implementation of appropriate green supply chain management and logistics principles.  More specifically, focus is put on the minimization of the environmental burden and the maximization of supply chain sustainability of the agrifood supply chain.  The application of such a framework could result into substantial reduction of CO2 emissions both by the additional production of other biofuels from waste, as well as the introduction of a novel intelligent logistics network, in order to reduce the harvest and transportation energy input.  Moreover, the expansion of the biomass feedstock available for biofuel production can provide adequate support towards avoidance of food/fuel competition for land use.   Keywords: supply chain management, green supply chains, sustainable development, agrifood secto