1,721,155 research outputs found
Composite plate mechanical characterisation through dynamic tests
No full textA reliable and efficient method for characterising the mechanical properties of composite plates has been developed. The effective mechanical properties of the composite plate are estimated from its natural frequencies, which are measured experimentally. Initially, the possibility of applying various combinations of boundary conditions is explored through the use of knife-edge supports in the context of a multi-step characterisation approach. Since the simulation of simple support conditions requires significant time and effort to achieve accuracy and repeatability, the totally free-edge condition is adopted, which is commonly accepted as simple and reliable. The characterisation approach based on free plate vibration experiments is designed for applications involving a large number of specimens with identical geometry. While it is feasible to expand it so that it would be applicable to a more complicated specimen geometry, the method has been demonstrated with plate specimens.
The characterisation procedure is based upon iterative minimisation of the sum of the squared differences between the measured natural frequencies and those corresponding to the updated material prediction. Similar approaches reported in the literature use a full-scale dynamic analysis in order to predict frequencies, resulting in a time consuming characterisation process. The application of such an approach to a large number of specimens with a complicated geometry would require finite element analysis, thus lengthening further the characterisation process. This thesis addresses this issue by making use of metamodelling for approximating the relationship between the material properties and the corresponding natural frequencies. This results in a much quicker in-situ characterisation process. The metamodels are based on radial basis functions, with the training data selected using a forward subset selection method. The procedure is applied to characterising four epoxy/glass composite specimens and the results are compared with those from static tests. Inaccuracies in both dynamic and static test measurements as well as in metamodelling are considered as potential sources of error in material properties prediction. A further refinement of the strategy also accounts for mode shape information whereby the error minimisation is carried out over the frequencies belonging to similar modes. The strategy has been demonstrated successfully through simulated data with most of the properties predicted with a high degree of accuracy and in short characterisation time.
The discussion on scope for further enhancement of the proposed strategy is primarily focused on possible refinements of metamodelling and on improvements in experimental techniques and apparatus in order to achieve even higher accuracy in frequency predictions and measurements, respectively
KENYAMANAN LINGKUNGAN KERJA DAN PRODUKTIVITAS KERJA DI UNIT
No full textUpaya yang dilakukan perusahaan untuk menjaga kualitas jamur merang yaitu dengan melakukan sortasi. Proses sortasi jamur merang
dilakukan setelah panen yaitu pada siang hari yang merupakan suhu tertinggi pada kurun waktu satu hari. Tenaga kerja pada proses sortasi
membutuhkan kondisi lingkungan kerja yang nyaman untuk membantu tenaga kerja dalam memilih jamur merang yang dibutuhkan
konsumen. Lingkungan kerja yang tidak nyaman dapat menurunkan konsentrasi dan mempercepat kelelahan sehingga dapat menurunkan
produktivitas kerja. Oleh karena itu diperlukan suatu rancangan lingkungan kerja yang ergonomis untuk meningkatkan produktivitas kerja
karyawan. Penelitian ini dilakukan dengan mengumpulkan beberapa data yaitu kondisi lingkungan kerja, persepsi karyawan terhadap
lingkungan kerja, dan produktivitas kerja karyawan selama 30 hari. Semua data yang diperoleh dianalisis dengan analisa deskriptif. Aspek
lingkungan kerja yang dinyatakan tidak nyaman dapat menentukan desain lingkungan kerja yang diberikan sebagai rekomendasi yang
dianalisis dengan Metode Perbandingan Eksponensial (MPE). Hasil studi menunjukkan bahwa aspek suhu udara merupakan aspek yang
membuat pekerja merasa sangat tidak nyaman. Permasalahan tersebut dapat ditangani dengan beberapa alternatif yang kemudian akan
dipilih satu alternatif terbaik antara lain pemberian kipas angin, pemasangan terpal, dan pemindahan tempat kerja ke dalam ruangan.
Berdasarkan hasil analisis, alternatif terbaik yang merupakan alternatif yang memiliki nilai tertinggi adalah pemberian kipas angin sehingga
alternatif tersebut dapat dijadikan sebagai rekomendasi desain lingkungan kerja yang diharapkan dapat meningkatkan produktivitas kerja
karyawan
Composite plate mechanical characterisation through dynamic tests: a numerical simulation
No full textA metamodelling approach to mechanical characterisation of anisotropic plates
No full textThe proposed characterization method is based on the knowledge of free vibration characteristics of plate specimens. Effective laminate properties are estimated through minimization of the error between known and predicted natural frequencies. Metamodeling is used for approximating the relationship between the material properties and the corresponding natural frequencies. This results in an economical characterization process, applicable to a large number of specimens of various shapes and dimensions. The proposed strategy is first tested on a range of hypothetical composite materials with numerically simulated test results, then applied to reliable published experimental data. It is thus shown to have the potential of a fast and accurate, in-situ characterization too
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
OPTIMASI PRODUK INDUSTRI KERUPUK MENGGUNAKAN LINEAR PROGRAMMING
No full textTujuan penelitian ini adalah merumuskan model optimasi pengalokasian komposisi tepung tapioka dan jam orang kerja dalam
rangka mendapatkan keuntungan yang maksimal dan menentukan jumlah produk yang diproduksi setiap jenisnya agar mendapatkan
keuntungan yang maksimal. Penelitian ini dilakukan di home industri Agus Jaya Makmur Karang Mluwo Mangli Jember. Tahapan
penelitian meliputi studi pendahuluan mencangkup studi pustaka, observasi lapang dan wawancara dari responden kunci, menentukan
fungsi tujuan dan fungsi kendala, pengolahan data menggunakan metode simpleks. Hasil analisis penelitian dapat diketahui untuk
mendapatkan hasil yang optimal harus memproduksi kerupuk udang/ikan sebesar 161,89 kg per hari dengan memproduksi kerupuk unyil
73 kg per hari dan kerupuk barabir 71 kg per hari dengan selisih keuntungan dari sebelum dan setelah dilakukan optimasi sebesar Rp
512.882,1
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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