1,720,958 research outputs found
Generazione di manichini virtuali da dati antropometrici ed applicazioni con strumenti di modellazione umana virtuale
Full text linkThe use of proactive ergonomics has become a priority for the study of the operator’s functionality in the working context, as well as in the optimization of work tasks and in the workplace design. The application of proactive ergonomics is adept to foresee and deal with changes and potential problems derived from the evolution of the industrial world. For these reasons, there is the necessity to use Digital Human Modeling (DHM) tools; they are capable to analyze postures and to perform ergonomic assessments according to international technical standards. In the first part of the thesis, a general overview of the different DHM tools is presented and some applications are shown. In particular, the study investigates the strengths and limitations of a multibody model developed in collaboration between industry and university. The postural angles of trunk bending and arm elevation of the model are defined in accordance with international regulations: ISO 11226:2000 and UNI EN 1005/4:2009. Since, the model is characterized by a limited number of degrees of freedom, it has been compared with the reference literature in order to validate it. Subsequently, the model was used for the verification of three case studies of real workstations, highlighting its usefulness in the design for different anthropometries of the operator. The postural angles, calculated in the validation study, were used to generate continuous postural maps with different interpolation methods. The postural maps were normalized with respect to main anthropometric measurements, in order to achieve results that can be generalized to different anthropometries of the operator. In the second part of the thesis, the project: “La Fabbrica si Misura”, developed in collaboration with Fiat Chrysler Automobiles (FCA) and with Istituto Nazionale Assicurazione Infortuni sul Lavoro (INAIL) is described. This project includes the measurement of a sample of 3000 male and female workers each, within the Italian production plants of FCA. This survey led to the generation of an updated anthropometric database of the Italian working population. The data were statistically analyzed in order to estimate the anthropometric models of the main percentiles that are referred to during design and to highlight significant anthropometric differences due to age and the geographical area of the sample. Among the utilities of the database, the generation of anthropometric models to update the virtual manikins of DHM tools is of particular interest. In the third and last part of the thesis, models of virtual manikins were obtained with various approaches; the different models were compared to highlight the differences and guide their choice in the assessment and design of workstations. A reliable estimate of the anthropometric measurements of the working population is particularly important in "human-centered design" and can support the design of "adaptable" workstations. Furthermore, it can correctly address the design of protective or auxiliary wearable devices such as the exoskeletons
Assessment of Anthropometric Differences in the Design of Workstations: Case Studies of an Automotive Assembly Line
Full text linkThe study investigates how the anthropometric differences in the postural analysis of workstations affect the ergonomic risk assessments. Three manual assembly operations from a car production line were selected as case studies. Postural analyses were performed through virtual manikins and selected operations were reproduced in physical in the lab. The program Siemens Teamcenter Visualization Mockup® was initially used to simulate the interaction of an "average-size" male worker with the workplace. Further analyses were carried out through a multibody model to verify the accessibility and postural comfort of different anthropometric percentiles. Results demonstrate the importance of a postural assessment also for limiting users, especially in case the assembly line cannot be adjusted to the operator's anthropometry, and the benefit of easy-to-use simulation tools to assist the ergonomist in the workstations design and to ensure the required comfort for all operators
A Simple Multibody 2d-model for Early Postural Checks in Workplace Design
Full text linkPosture prediction is one of the most important aspects of virtual modeling tools used for the workplace design: once the work point to reach is defined, the posture prediction module allows simulating, through inverse kinematics, the posture the operator is likely to assume. The paper presents a simple multibody 2D-model created for early postural checks in the design phase. The tool is a spreadsheet created in Microsoft Excel environment, with the support of Visual Basic. The principal output of the model in terms of angles of trunk bending and upper arm elevation, set in compliance with the technical standards, are compared to the results of an established software tool for ergonomic analyses, the 3D Static Strength Prediction Program (3DSSPP). Finally, possible differences in terms of moments on the L5/S1 and the shoulder joints introduced by the simplified kinematics of the 2D manikin are discussed
Mappatura di angoli posturali e confronto tra strumenti di Digital Human Modeling per prove di raggiungibilità
No full textPosture prediction is one of the most important aspects of virtual modeling tools: once the work point to be reached is defined, posture prediction allows simulating, through inverse kinematics, the posture the operator is most likely to assume. Aim of this work is the comparison between two virtual modeling tools characterized by a different degree of complexity of the manikin kinematics. The first tool, developed by the University of Michigan and implemented in codes such as Jack Siemens, is the 3DSSPP software (3D Static Strength Prediction Program), while the second tool, developed in FCA, is a spreadsheet created in Microsoft Excel environment, with the support of Visual Basic. Comparisons were made for the angles of trunk bending and the arm elevation, and postural assessments consistent with the ISO 11226 and UNI EN 1005/4 standards were associated to them. The proposed study provides a database of postural angles for reachability operations and shows a comparison between two virtual simulation tools: in particular, the study investigates on the strengths and the limitations of a simple and rapid tool, comparing it with the reference literature model
Comprehensive mappings of postural angles on a normalized plane of reachability
No full textIn the industrial context of workstation design, the role of ergonomics in primary prevention of musculoskeletal disorders is increasingly important. Simple tools and guidelines for early postural checks are needed toassist the analyst through the dynamic reality of workstation design. In this work, a method for generating mappings of the operator's reachability is proposed. The reachability plane is normalized with respect to characteristic anthropometric body dimensions so that the postural maps can address any operator, regardless of his/her anthropometry. The mappings of trunk bending and upper arm elevation angles, defined in accordance with the international technical standards, make use of the traffic light scheme to ensure a valid and easy-to-interpret support to the analyst
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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