1,721,135 research outputs found
Experimental evaluation and comparison of Mobile Spatial coordinate Measuring System(MScMS)network localization procedures
No full text
Analysing uncertainty contributions in dimensional measurements of large-size objects by ultrasound sensors
Full text linkAccording to the ever-increasing interest in metrological systems for dimensional measurements of large-size objects in a wide range of industrial sectors, several solutions based on different technologies, working principles, architectures and functionalities have been recently designed. Among these, a distributed flexible system based on a network of low-cost ultrasound (US) sensors - the Mobile Spatial coordinate Measuring System (MScMS) - has been developed. This article presents a possible approach to assess the system uncertainty referring to the measured point coordinates in the 3D space, focusing on the sources of measurement uncertainty and the related propagation la
Corrective algorithms for measurement improvement in MScMS-II (Mobile Spatial coordinate Measurement System)
Full text linkThis paper presents a set of algorithms for the correction of measurement errors of a prototype system designed for Large Scale Dimensional Metrology (LSDM) applications. The system, developed in the Quality and Industrial Metrology Laboratory of Politecnico di Torino, is based on the principles of photogrammetry and consists of a set of cameras wirelessly connected to a central unit able to track the position of a portable contact probe. Due to its architecture the system is affected by several systematic error sources. This paper addresses some of them: the distortion of the lenses, the dimension of the probe tip and the kinematic of the probe. By means of the implementation of appropriate mathematical correction models, the overall system performance is significantly improved as shown by the conducted test
Determining the extrinsic parameters of a network of Large-Volume Metrology sensors of different types
Full text linkLarge-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
METODO PER LA TARATURA DI UN SISTEMA DI MISURA LVM IBRIDO
Full text linkLa presente invenzione si riferisce ad un metodo per il calcolo dei parametri estrinseci di una rete di sensori per Large-Volume Metrology (LVM); detta rete di sensori LVM comprende almeno un primo tipo di sensori LVM ed un secondo tipo di sensori LVM. Il metodo oggetto della presente invenzione comprende i seguenti passi: (i) acquisire una o più misure mediante ciascuno di detti sensori LVM ed un dispositivo tastatore disposto in una pluralità di punti all’interno di un volume di misura, detto dispositivo tastatore comprendendo almeno un primo target compatibile con detto primo tipo di sensore LVM ed un secondo target compatibile con detto secondo tipo di sensore LVM; (ii) definire un sistema di equazioni combinato comprendente dette una o più misurazioni ottenute da detta rete di sensori LVM; e, (iii) determinare i parametri estrinseci della rete di sensori LVM in funzione del sistema di equazioni combinato
Impact of Journals and Academic Reputations of Authors: A Structured Bibliometric Survey of the IEEE Publication Galaxy
No full textResearch problem: This study explores the use of bibliometric indicators to objectively evaluate IEEE scientific journals from two different perspectives: (1) journal impact and diffusion and (2) the academic reputation of journal authors. Research questions: (1) Which journals are better at selecting articles with high scientific impact (measured by average citations per article), and publishing authors with strong reputations (measured by -indices)? (2) Does the impact of journal articles correlate positively with the reputations of their authors? and (3) Can bibliometric indicators provide a simple way for journal editors to monitor journal performance in a manner complementary to traditional ISI impact factor (IF)? Literature review: This paper reviews literature on citation analysis, a bibliometric method of measuring impact based on the number of times a work is cited, and explains such bibliometric indicators as , Hirsch index, and IF which measure the impact of a journal, and introduces a new indicator called -spectrum to objectively measure the reputation of a journal's author group. Methodology: This quantitative study performed citation analysis on 250,000 authors in 110 IEEE journals using citation statistics from the Google Scholar, Web of Science, and Scopus databases to construct the -spectrum indicator. The authors used automated filtering techniques to exclude questionable author data. Results and conclusions: The first phase of analysis indicated significant differences among IEEE publications in journal impact, and found that the -index and were suitable for evaluating journals except in their most recent five years where annual rankings are proposed instead. The second phase of analysis found that -spectra distributions of author reputation differ among journals in a single year, and are generally stable for a single journal over five years. Maps were constructed to locate journals graphically based on the complementary indicators of impact and reputation, and to show changes in impact and reputation over time. The maps indicated that journals with high impact tend to have authors with high reputations but the opposite is not necessarily true. Suggestions were made to explain different combinations of high and low impact and reputation for journals. The use of maps complements IF and provides a simple tool to monitor journal reputation at the time of most recent publication. The study is limited by assumptions about the value of citations, the reliability of search engine statistics, and the homogeneity of IEEE journal citation practices, as well as the failure to account for coauthors, article age, and authors who publish multiple times per year in the same journal. Future research could examine non-IEEE journals and normalize subfields within IEEE journals to avoid favoring fields that use more citations
ISO 9001 certification and corporate performance of Italian companies
No full textPurpose - The purpose of this paper is to verify a possible relationship between quality management system certification according to ISO 9001 standard and risk of failure of Italian companies. Design/methodology/approach - A synthetic index which summarize the most crucial economic/financial aspects of the studied companies is assumed as the response variable of a statistical model for studying the effects of four specific factors: certification, company size, regional development and manufacturing sub-sector. The analysis is conducted on a sample of Italian companies belonging to different manufacturing sub-sectors. The used data are obtained from the database Aida® by Bureau van Dijk and from the database of the Italian accreditation body Accredia. The study is based on analysis of variance (ANOVA) and contingency tables. Findings - Preliminary results of ANOVA show that only company size, regional development and manufacturing sub-sector can be considered fully significant. Furthermore, the major conclusion from the analysis of contingency tables is that ISO 9001 certification is connected to the legal status (active, not active) of a company only for a portion for the studied manufacturing sub-sectors. Hence, the scenario is quite variegated and a significant positive interaction between certification and corporate performance is not always confirmed. Research limitations/implications - Although the research shows some interesting results, it is liable to extensions and improvements. In particular, at the current exploratory level, it is limited to a specific period of time and considers only the Italian sector, but it could be extended to a wider number of years and to European and international level. Practical implications - The study opens a way for a number of important questions about the meaning, usefulness and effectiveness of ISO 9001 certification. In particular, it may be time to ask whether the paradigm of certification actually needs a radical rethink. Originality/value - This work represents a first exploratory attempt to correlate the risk of failure with the achievement of ISO 9001 certification. There are several similar works in literature which, however, focus mainly on sectorial aspects of the corporate background
Rankings and decisions in Engineering. Conceptual and practical insights
No full textImagine that some designers individually formulate rankings of different alternative design concepts for a new product and should identify the best one collectively. Or imagine that some reliability engineers, when qualitatively assessing the severity of potential failures of a production machine, should aggregate their subjective rankings into a single collective judgment that represents them as best as possible.
These are two of the innumerable applications of the so-called ranking aggregation problem, which consists in aggregating multiple subjective rankings into a single collective judgment. Despite the importance of this problem in engineering,
the current scientific literature is somewhat fragmented and unstructured. The practical applications are often managed borrowing methodological approaches from more traditional contexts—such as social choice/voting theory, economics, psychometrics, multiple criteria decision making/analysis—without necessarily being familiar with the scientific literature.
This fragmentation and poor structuring, together with the limited level of methodological detail, probably depends on the fact that researchers and practitioners in engineering hardly have in-depth knowledge of decision-making techniques and tools. This limitation certainly makes it challenging to choose the most appropriate methodological approaches, depending on (1) the characteristics of the
practical context, (2) the information available, and (3) the desired output data.
This book tries to overcome the above limitation, addressing an audience of academics, practitioners, and technicians working in the engineering field, who do not necessarily have in-depth knowledge of decision-making problems. The aim is to deeply investigate the ranking decision problem and the related features (such as input/output data, simplification hypotheses, and practical implications) and to
illustrate several methodological approaches in a structured way. The description, intended to provide a sufficiently broad overview of state of the art, is supported by pedagogical examples and real-life case studies.
Although scientifically rigorous, the formalization of problems is not too heavy in terms of mathematical technicalities, not to undermine the legibility and fluency of the entire document. On the other hand, interesting cues and bibliographical references are available for the reader who wishes to deepen technical aspects.
With this book, the authors aim to provide the reader with a selection of the most interesting, curious, and useful topics that they have developed in over twenty years of research on decision making within the engineering field. In addition to providing an organic overview of the most consolidated methodological approaches, the book illustrates innovative techniques, which could also be profitably used outside the boundaries of engineering.
The rest of the book is organized into six chapters, which are briefly described below.
Chapter 2 formally defines the ranking aggregation problem, focusing the attention on the characteristic input and output data.
Chapter 3 explores the concept of ranking from the perspective of the so-called measurement theory and its derivations.
Chapter 4 focuses on evaluating the association/concordance of expert rankings, referring to some established and innovative techniques from the scientific literature.
Chapter 5 illustrates in detail a selection of (consolidated and innovative) ranking aggregation techniques, analyzing their strengths and weaknesses. The description is accompanied by several pedagogical examples.
Chapter 6 describes some quantitative tools to check the degree of consistency between the collective judgment and the input data, in a practical and intuitive way.
Chapter 7 concludes the book, presenting several real-world examples of the ranking aggregation problem within engineering, with special reference to the activities of design, development, and evaluation of the quality and reliability of products, services, and manufacturing processes
A new methodology to design multi-sensor networks for distributed Large-Volume Metrology systems
No full textDistributed Large-Volume Metrology (LVM) systems are mainly used for industrial applications concerning assembly and dimensional verification of large-sized objects. These systems generally consist of a set of network devices, distributed around the measurement volume, and some targets to be localized, in contact with the measured object's surface or mounted on a hand-held probe for measuring the points of interest. Target localization is carried out through several approaches, which use angular and/or distance measurements by network devices. This paper presents a new methodology to support the design of networks of devices for distributed LVM systems based on triangulation (i.e., systems in which network devices perform angular measurements only). It is assumed that these systems use multi-sensor networks including two typologies of devices: some are accurate but expensive and other ones are less accurate but cheaper. The goal of the methodology is establishing a link between the following parameters: (i) density of network devices, (ii) mix between the two typologies of network devices, (iii) measurement uncertainty, and (iv) cost. The methodology allows to estimate the most appropriate density and mix between the two typologies of network devices, so that the distributed LVM system is conforming with the required measurement uncertainty and cost. The methodology relies on a large number of simulated experiments, defined and implemented using a dedicated routine; feasibility and practicality is tested by preliminary experiments on a multi-sensor photogrammetric system, developed at Politecnico di Torino - DIGEP
- …
