690 research outputs found

    Design of AGV systems in working environments shared with humans: A multi case study

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    To meet the challenges and needs of an ever-changing market and as part of the fourth industrial revolution, factories are transforming into increasingly automated environments. A widely used and well-established solution today is Automated Guided Vehicles (AGVs), which often work closely with humans in crowded environments. Thus, in addition to flexibility, another important criterion associated with automatic handling systems is safety. The purpose of this work is to show how the involvement of three different but equally important roles in the design of an AGV system can benefit the whole project. The advantage of considering three different perspectives is the possibility of obtaining a more complete vision from the earliest stages of implementation, avoiding, as far as possible, the need to make changes in the next stages, which would generate higher costs than necessary. The article is based on two case studies, each one set in a major European manufacturing company: the first one is an Italian automotive manufacturer and the second one is a Swedish manufacturer of mechanical components. Both case companies apply AGVs in their material handling processes and, accordingly, have experience of both implementing and operating AGV systems. The article applies semi-structured interviews to study the three key roles, highlighting the key points for each role and showing the common issues that emerged from the interviews

    A Two-Phase Mass Flow Rate Model for Nitrous Oxide Based on Void Fraction

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    In the field of space propulsion, self pressurized technology is an example of innovation capable of improving system performances through reduction of volumes and other optimizations. Potential applications are widespread and not limited to the propulsion panorama: from on-orbit maneuvering to in-orbit servicing, from refueling of satellites at the end of life to in situ resource exploitation for missions headed towards remote objects of the solar system. However, important drawbacks have been reported for these systems: modeling of fluids and thermal phenomena is complex, thus preventing accurate performance predictions. As a result, no comprehensive and accurate model capable of describing the dynamics of a self-pressurizing propellant tank has been developed so far. In this context, this paper proposes a two-phase mass flow rate model based on void fraction. N2O has been selected due to its use as a green and self-pressurized propellant for in-space propulsive applications. The aim of this paper is to describe the current mass flow rate models present in the literature for this fluid and compare the new model with the one proposed by Dyer. A model validation is also offered, and a test campaign is mentioned. Finally, preliminary results are shown and discussed: results are then compared with the ones obtained through the Dyer model, in order to retrieve a comprehensive comparison among the two simulation frameworks. Comments on the results are added, showing the improvements as well as the limitations of the proposed framework

    Actors and factors - bridging social science findings and urban land use change modeling

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    Recent uneven land use dynamics in urban areas resulting from demographic change, economic pressure and the cities’ mutual competition in a globalising world challenge both scientists and practitioners, among them social scientists, modellers and spatial planners. Processes of growth and decline specifically affect the urban environment, the requirements of the residents on social and natural resources. Social and environmental research is interested in a better understanding and ways of explaining the interactions between society and landscape in urban areas. And it is also needed for making life in cities attractive, secure and affordable within or despite of uneven dynamics.\ud The position paper upon “Actors and factors – bridging social science findings and urban land use change modeling” presents approaches and ideas on how social science findings on the interaction of the social system (actors) and the land use (factors) are taken up and formalised using modelling and gaming techniques. It should be understood as a first sketch compiling major challenges and proposing exemplary solutions in the field of interest

    Microturbulence studies in RFX-mod

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    Present-days Reversed Field Pinches (RFPs) are characterized by quasi-laminar magnetic configurations in their core, whose boundaries feature sharp internal transport barriers, in analogy with tokamaks and stellarators. The abatement of magnetic chaos leads to the reduction of associated particle and heat transport along wandering field lines. At the same time, the growth of steep temperature gradients may trigger drift microinstabilities. In this work we summarize the work recently done in the RFP RFX-mod in order to assess the existence and the impact upon transport of such electrostatic and electromagnetic microinstabilities as Ion Temperature Gradient (ITG), Trapped Electron Modes (TEM) and microtearing modes.Comment: Work presented at the 2010 Varenna workshop "Theory of Fusion Plasmas". To appear in Journal of Physics Conference Serie

    Efficacy of adalimumab as second-line therapy in a pediatric cohort of crohn’s disease patients who failed infliximab therapy: The Italian society of pediatric gastroenterology, hepatology, and nutrition experience

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    Background: Adalimumab (Ada) treatment is an available option for pediatric Crohn’s disease (CD) and the published experience as rescue therapy is limited. Objectives: We investigated Ada efficacy in a retrospective, pediatric CD cohort who had failed previous infliximab treatment, with a minimum follow-up of 6 months. Methods: In this multicenter study, data on demographics, clinical activity, growth, laboratory values (CRP) and adverse events were collected from CD patients during follow-up. Clinical remission (CR) and response were defined with Pediatric CD Activity Index (PCDAI) score ≤10 and a decrease in PCDAI score of ≥12.5 from baseline, respectively. Results: A total of 44 patients were consecutively recruited (mean age 14.8 years): 34 of 44 (77%) had active disease (mean PCDAI score 24.5) at the time of Ada administration, with a mean disease duration of 3.4 (range 0.3–11.2) years. At 6, 12, and 18 months, out of the total of the enrolled population, CR rates were 55%, 78%, and 52%, respectively, with a significant decrease in PCDAI scores (P<0.01) and mean CRP values (mean CRP 5.7 and 2.4 mL/dL, respectively; P<0.01) at the end of follow-up. Steroid-free remission rates, considered as the total number of patients in CR who were not using steroids at the end of this study, were 93%, 95%, and 96% in 44 patients at 6, 12, and 18 months, respectively. No significant differences in growth parameters were detected. In univariate analysis of variables related to Ada efficacy, we found that only a disease duration >2 years was negatively correlated with final PCDAI score (P<0.01). Two serious adverse events were recorded: 1 meningitis and 1 medulloblastoma. Conclusion: Our data confirm Ada efficacy in pediatric patients as second-line biological therapy after infliximab failure. Longer-term prospective data are warranted to define general effectiveness and safety in pediatric CD patients

    Tryptophan Metabolism as Source of New Prognostic Biomarkers for FAP Patients

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    Familial adenomatous polyposis (FAP), a common inherited form of colorectal cancer (CRC), causes the development of hundreds to thousands of colonic adenomas in the colorectum beginning in early adolescence. In absence of a prophylactic surgery, FAP patients almost inevitably develop CRC by the age of 40 to 50. The lack of valuable prognostic biomarkers for FAP patients makes it difficult to predict when the progression from adenoma to malignant carcinoma occurs. Decreased tryptophan (TRP) plasma levels and increased indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan hydroxylase 1 (TPH1) enzymatic activities have been associated to tumour progression in CRC. In the present study, we aimed at investigating whether an altered TRP metabolism might also exist in FAP patients. Our results highlighted that plasma levels of TRP and its main catabolites are comparable between FAP patients and healthy subject. On the contrary, FAP patients presented significantly higher TRP levels with respect to high-grade adenoma (ADE) subjects and CRC patients. Obtained data lead us to evaluate IDO1 and TPH1 enzymes activity in the study groups. For both enzymes, it was possible to discriminate correctly between FAP subject and ADE/CRC patients with high sensitivities and specificities. By receiver operating characteristic (ROC) curve analysis, the cut-off values of IDO1 and TPH1 enzymatic activities associated to the presence of an active malignant transformation have been calculated as >38 and >5.5, respectively. When these cut-off values are employed, the area under the curve (AUC) is > 0.8 for both, indicating that TRP metabolism in patients with FAP may be used to monitor and predict the tumorigenic evolution

    Narrativa e metacognição na formação de professores e pesquisadores em educação em ciências

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    Este trabalho focaliza o modo como professores-pesquisadores da área de Ciências e Matemática, estudantes de pós-graduação em Educação, ao narrarem sobre suas experiências, expressam concepções sobre educação em ciências e o próprio processo de aprendizagem. As narrativas, na forma de "Crônica da Disciplina", constituem-se num gênero de narrativa que se expressa em linguagem acessível e espontânea e cuja estrutura aberta e flexível, misturando conhecimentos objetivados da sociedade e universos subjetivos de representações, permitindo uma aproximação do pensamento do formando sobre fenômenos sociais que vão sendo interpretados por ele, tendo como referente suas experiências humanas. Dessa forma, foi possível identificar os 'efeitos de aprendizagem' que essas narrativas provocaram nos estudantes e fornecer pistas para a formação reflexiva de professores

    Narrativa e metacognição na formação de professores e pesquisadores em educação em ciências

    Get PDF
    Este trabalho focaliza o modo como professores-pesquisadores da área de Ciências e Matemática, estudantes de pós-graduação em Educação, ao narrarem sobre suas experiências, expressam concepções sobre educação em ciências e o próprio processo de aprendizagem. As narrativas, na forma de "Crônica da Disciplina", constituem-se num gênero de narrativa que se expressa em linguagem acessível e espontânea e cuja estrutura aberta e flexível, misturando conhecimentos objetivados da sociedade e universos subjetivos de representações, permitindo uma aproximação do pensamento do formando sobre fenômenos sociais que vão sendo interpretados por ele, tendo como referente suas experiências humanas. Dessa forma, foi possível identificar os ‘efeitos de aprendizagem’ que essas narrativas provocaram nos estudantes e fornecer pistas para a formação reflexiva de professores
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