1,720,963 research outputs found
Optimal setup of a multihead weighing machine
Full text linkMultihead weighing machines are ubiquitous in industry for fast and accurate packaging of a wide variety of foods and vegetables, small hardware items and office supplies. These machines consist of a system of multiple hoppers that are filled with product which when discharged through a funnel fills a package to a desired weight. Operating the machine requires first to specify the product weight targets or setpoints that each hopper should contain on average in each cycle, which do not need to be identical. The setpoints selection has a major impact on the performance of a multihead weighing machine. Each cycle, the machine fills a package running a built-in knapsack algorithm that opens – or leaves shut – different combinations of hoppers releasing their content such that the total package weight is near to its target, minimizing the amount of product “given away”. In this paper, we address the open problem for industry of how to determine the setpoint weights for each of the hoppers before starting up the machine, given a desired total package weight. An order statistic formulation based on a characterization of near-optimal solutions is presented. This is shown to be computationally intractable, and a faster heuristic that utilizes a lower bound approximation of the expected smallest order statistic is proposed instead. The solutions obtained with the proposed methods can result in substantial savings for users of multihead weighing machines. Alternatively, the analysis presented could be used by management to justify the acquisition of new machines of this type
On a RSM approach to the multihead weigher configuration
No full textThe multihead weigher is a complex machine which has to be properly configured and managed by taking into account the
uncertainty of the load cells. Specifically, this paper focuses on
the configuration problem of the multihead weigher. First an objective function is proposed. This function considers both the
costs of “non conforming” packages (i.e. packages that have to
be scrapped or reworked because their weight is below the law
lower limit) and the cost of extra product (i.e. cost of material
that exceeds the target weight). Secondly, the paper presents an
approach to select the average weight to be set for each hopper
by combining a RSM (Response Surface Methodology) and a
multihead weighing machine simulator. The performance of the
proposed approach is presented and discussed
An Economical Approach to Stop an Experimental Campaign with the Aim of Reducing Cost
Full text linkNowadays, in a period of stagnation and economic crisis, the continuous improvement of the production technologies in order to optimize economic, energetic and productive resources is crucial. The increase in efficiency, measured in terms of cost reduction, is therefore a key problem that requires the attention of more and more companies and researchers. In particular, the productivity of a machining system and its related costs depend on the setup of the machining parameters. This choice plays a key role when the machining material is expensive, the production batch has a limited size and the tool to be used is new: typical examples are the aircraft and die/mold industries.
In order to optimally setup a machine, the study of the tool life according to the material and the machining parameters is critical. The expression of the tool life could be estimated using an appropriate experimental campaign, which should have a limited size in order to reduce the experimental costs. This approach becomes of primary importance when the production is not in series where the costs can be spread over a large number of pieces.
The aim of this paper is to propose a new methodology that stops the experimental campaign as soon as the expected gain in carrying on the experimentation does not justify the marginal cost of experimentation.
To prove our idea, a simple problem from the well-known turning cutting condition optimization is used and the optimization technique Response Surface Methodology is selected
On the Multihead Weigher Machine Setup Problem
Full text linkA multihead weigher machine (MWM) is a computer-controlled machine used to fill a package with small products or parts with a given target weight. MWMs are widespread in the food and non-food industries because of their high performance in terms of variety of products to be packed, high throughput and quality of the packaged items. Despite the popularity of these machines, no studies to date have addressed how to set up the operating parameters of these machines. In industrial practice, operators currently use ad hoc rules to setup an MWM, but the initial settings can have a dramatic effect on the machine performance. The aim of this paper is to formalize the setup problem and its main variables. Then an optimization technique is proposed to solve the problem
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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