22 research outputs found

    Determining the extrinsic parameters of a network of Large-Volume Metrology sensors of different types

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    Large-Volume Metrology (LVM) instruments – such as laser trackers, photogrammetric systems, rotary-laser automatic theodolites, etc. – generally include several sensors, which measure the distances and/or angles subtended by some targets. This measurements, combined with the spatial position/orientation of sensors (i.e., the so-called extrinsic parameters), can be used to locate targets in the measurement volume. Extrinsic parameters of sensors are generally determined through dedicated sensor calibration methods, which are based on repeated measurements of specific artefacts. The combined use of multiple LVM instruments enables exploitation of available equipment but may require multiple instrument-dedicated sensor calibrations, which inevitably increase set-up time/cost. This document presents a novel calibration method – called global calibration – which allows the extrinsic parameters of all sensors to be determined in a single process. The proposed method uses a special artefact – i.e., a hand-held probe with assorted types of targets and inertial sensors – and includes a data-acquisition stage, in which the probe is repositioned in different areas of the measurement volume, followed by a data-processing stage, in which an ad hoc mathematical/statistical model is used to determine the extrinsic parameters of sensors. Additionally, the proposed method includes the formulation of a system of linearized equations, which are weighed considering the uncertainty of input variables

    A structured comparison of decentralized additive manufacturing centers based on quality and sustainability

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    Companies are increasingly adopting decentralized manufacturing strategies to manage multiple, geographically scattered manufacturing centers that are characterized not only by similar types of equipment, working methods, and productions, but also by variable mixes and volumes. This trend also applies to additive manufacturing, a well-established technology that allows the flexibility and customization of production to be increased, without significantly increasing the per unit cost. Thus, the need arises to monitor the performance of individual centers in a structured way, and to make practical comparisons of such centers. However, achieving this task is not so straightforward, given the inevitable differences in the characteristics of manufacturing centers and their productions. This paper presents a methodology that can be used to analyze and com-pare the production performance of a plurality of manufacturing centers from two different viewpoints: (i) quality, through a multivariate statistical analysis of product data concerning conformity with geometrical specifications, and (ii) process sustainability, with the aim of achieving a reduction in energy consumption, carbon dioxide emissions, and manufactur-ing time, through regression models pertaining to the selected metrics. The proposed methodology can be adopted during regular production operations, without requiring any ad hoc experimental tests. The description of the method is supported by an industrial case study

    Publication and patent analysis of European researchers in the field of production technology and manufacturing systems

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    This paper develops a structured comparison among a sample of European researchers in the field of Production Technology and Manufacturing Systems, on the basis of scientific publications and patents. Researchers are evaluated and compared by a variegated set of indicators concerning (1) the output of individual researchers and (2) that of groups of researchers from the same country. While not claiming to be exhaustive, the results of this preliminary study provide a rough indication of the publishing and patenting activity of researchers in the field of interest, identifying (dis)similarities between different countries. Of particular interest is a proposal for aggregating analysis results by means of maps based on publication and patent indicators. A large amount of empirical data are presented and discusse

    Analysis of the Hirsch index's operational properties

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    The h-index is a relatively recent bibliometric indicator for assessing the research output of scientists, based on the publications and the corresponding citations. Due to the original characteristics of easy calculation and immediate intuitive meaning, this indicator has become very popular in the scientific community. Also, it received some criticism essentially because of its ‘‘low" accuracy. The contribution of this paper is to provide a detailed analysis of the h-index, from the point of view of the indicator operational properties. This work can be helpful to better understand the peculiarities and limits of h and avoid its misuse. Finally, we suggest an additional indicator ðf Þ that complements h with the information related to the publication age, not compromising the original simplicity and immediacy of understandin

    SMART-QUAL: a dashboard for quality measurement in higher education institutions

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    Purpose – The paper aims to define a dashboard of indicators to assess the quality performance of higher education institutions (HEI). The instrument is termed SMART-QUAL. Design/methodology/approach –Two sources were used in order to explore potential indicators. In the first step, information disclosed in official websites or institutional documentation of 36 selected HEIs was analyzed. This first step also included in depth structured high managers’ interviews. A total of 223 indicators emerged. In a second step, recent specialized literature was revised searching for indicators, capturing additional 302 indicators. Findings – Each one of the 525 total indicators was classified according to some attributes and distributed into 94 intermediate groups. These groups feed a debugging, prioritization and selection process, which ended up in the SMART-QUAL instrument: a set of 56 key performance indicators, which are grouped in 15 standards, and, in turn, classified into the 3 HEI missions. A basic model and an extended model are also proposed. Originality/value – The paper provides a useful measure of quality performance of HEIs, showing a holistic view to monitor HEI quality from three fundamental missions. This instrument might assist HEI managers for both assessing and benchmarking purposes. The paper ends with recommendations for university managers and public administration authorities

    ECMO for COVID-19 patients in Europe and Israel

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    Since March 15th, 2020, 177 centres from Europe and Israel have joined the study, routinely reporting on the ECMO support they provide to COVID-19 patients. The mean annual number of cases treated with ECMO in the participating centres before the pandemic (2019) was 55. The number of COVID-19 patients has increased rapidly each week reaching 1531 treated patients as of September 14th. The greatest number of cases has been reported from France (n = 385), UK (n = 193), Germany (n = 176), Spain (n = 166), and Italy (n = 136) .The mean age of treated patients was 52.6 years (range 16–80), 79% were male. The ECMO configuration used was VV in 91% of cases, VA in 5% and other in 4%. The mean PaO2 before ECMO implantation was 65 mmHg. The mean duration of ECMO support thus far has been 18 days and the mean ICU length of stay of these patients was 33 days. As of the 14th September, overall 841 patients have been weaned from ECMO support, 601 died during ECMO support, 71 died after withdrawal of ECMO, 79 are still receiving ECMO support and for 10 patients status n.a. . Our preliminary data suggest that patients placed on ECMO with severe refractory respiratory or cardiac failure secondary to COVID-19 have a reasonable (55%) chance of survival. Further extensive data analysis is expected to provide invaluable information on the demographics, severity of illness, indications and different ECMO management strategies in these patients

    Analysis of the Hirsch index's operational properties

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    The h-index is a relatively recent bibliometric indicator for assessing the research output of scientists, based on the publications and the corresponding citations. Due to the original characteristics of easy calculation and immediate intuitive meaning, this indicator has become very popular in the scientific community. Also, it received some criticism essentially because of its "low" accuracy. The contribution of this paper is to provide a detailed analysis of the h-index, from the point of view of the indicator operational properties. This work can be helpful to better understand the peculiarities and limits of h and avoid its misuse. Finally, we suggest an additional indicator (f) that complements h with the information related to the publication age, not compromising the original simplicity and immediacy of understanding.Hirsch index Performance evaluation Citations Ranking Indicator properties Operational properties Publication year

    Withdrawn: Multi-Target Modular probe for Large-Volume Metrology

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    The relationship between research and teaching in HEIs: recent empirical findings

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    Purpose: Since 1950s a plurality of studies focused on the relationship between research and teaching in HEIs, with conflicting conclusions. While some studies see these activities as synergically linked, others theorize their decoupling or even negative tension. This divergence is probably because most of the investigations are based on heterogeneous, limited and difficult-to-generalise data. This paper deepens the study of the research-teaching relationship, from the dual perspective of the workload and quality of results achieved by individual academics. Study design: This study relies on various empirical data – e.g., bibliometric indicators, teaching-satisfaction indices, number of courses thought, number of students, etc. – for hundreds of academics from Politecnico di Torino (PoliTO), i.e., one of the largest technical universities in Italy. After constructing several indicators concerning research and teaching, their (potential) correlation will be analysed. Findings: This study seems to exclude both (i) the existence of a negative relationship between research and teaching in terms of workload, contradicting the hypothesis that “Those who do more teaching have less time for research and vice versa”, and (ii) the existence of a positive relationship in terms of quality of results obtained, contradicting the hypothesis that “Those who obtain high quality results in research are likely to do the same in teaching and vice versa”. Originality/value: The paper analyses a relatively large sample of academics – i.e., 251 from PoliTO and more than 3000 from other Italian universities – and adopts several quantitative bibliometric indicators, some of which are discipline-normalised. Limitations: The study is limited to academics from PoliTO. Assessment of research and teaching workloads could have been more in-depth with additional data, such as information on ongoing research projects, students tutored for internships, theses, dissertations, etc

    PFMEA for distributed manufacturing environments

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    The Process Failure Mode and Effects Analysis (PFMEA) is a powerful tool to design and maintain reliable manufacturing processes, investigating the potential failure modes from the threefold perspective of severity, occurrence and detection. Being progressively characterized by decentralized networks of flexible manufacturing facilities, the current scenario somehow hampers the application of the traditional PFMEA, which requires the joint work of a group of experts formulating collective judgments. This paper revisits the traditional PFMEA approach and integrates it with the ZMII-technique – i.e., a recent aggregation technique based on the combination of the Thurstone’s Law of Comparative Judgment and the Generalized Least Squares method – which allows experts dispersed through organizations and countries to formulate their judgments individually. The revisited approach also includes a relatively versatile response mode and overcomes several other limitations of the traditional approach, including but not limited to: (i) arbitrary categorization and aggregation of the expert judgments, (ii) disregarding the dispersion of these judgments, and (iii) disregarding the uncertainty of results. The description is supported by a real-life application example concerning a plastic injection-moulding process
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