1,720,986 research outputs found
Study on the benefits of lattice structures within the framework of high-performance structural design: a case study
Full text linkThe design and development of the innovative structures require rigorous and robust efforts when they are based on complex geometries, involving multiphysics functionalities/behavior, subjected to other assembly components, and to
be prototyped with additive manufacturing. Additive manufacturing allows us to explore new topologies that may fulfill many functional requirements. Lattice structures are part of these new topologies, providing abundant promising
advantages, such as lightweight design, functional graded solutions, etc. In this work we investigate the state of the art of lattice structures in respect of their related field of applications and we apply this knowledge to support the design
of a high-performance device, such as next-generation cryogenic detectors for particle physics research. Lattice structures pose many challenges in the field of the CAD-CAE approaches, since it requires managing a multiscale modelling domain. This may reduce the capability of young engineers to completely accomplish the design workflow with efficiency. This thesis aims to investigate a design-development workflow suitable to guarantee this efficiency, and
subsequently facilitates the development of innovative structures with virtual prototyping and additive manufacturing.
The followed approach was:
▪ To investigate the state of the art of lattice design modelling and
simulation.
▪ To define a design-development workflow suitable to accomplish
functional, performance and process requirements.
▪ To test the design-development workflow through the design of a highperformance device.
The proposed design-development workflow is based on a comprehensive list of requirements engulfing all the design, functional, assembly, and manufacturing requirements to fulfill the desired objectives. This list of requirements is then
successfully translated into the initial design phase to facilitate the subsequent 3D modelling, manufacturing, and assembly phases.
The validation case study is a real application of BULLKID Project, provided by the industrial partner INFN (Istituto Nazionale di Fisica Nucleare/Italian National Institute of Nuclear Physics) Rome (Italy). BULLKID is developing the
next-generation cryogenic detectors for Particle Physics research, in the field of neutrino and dark matter. The detectors are operated at 10 mK temperature in a high vacuum and light-tight environment. This case study is basically a multiphysics problem, and it is based on multi-objective design optimization. Main challenges concerning the research work are to hold the detector with the least possible mechanical vibrations, excellent thermal contact, and stacking up several of them in a closely packed structure. In addition, the proposed design should be lightweight, thermal efficient, and the protype of the wafer holders and the wafer holding ring should be developed with additive manufacturing (AM) technology (SLM technique) to ensure maximum flexibility in the design and to obtain the fine features required for the final structure.
The design optimization is carried out in two stages: first without the lattice structure, and second with the lattice structure. In the first optimization stage, it is ensured that the optimized design (without lattice) has the capability to stack up three wafer assemblies successfully in the prototype, withstand a fail-safe cryogenic operation (ensuring an improved rigidity with respect to vibration issues detected during the experimental run of the previous design), and the
prototyping of complex components with AM in accordance with the stipulated requirements. In the second optimization stage, the infill volume lattice (with an optimal cell structure) is employed in the wafer holding ring, under the consideration of the assembly constraints, to further reduce the structural weight, reduce the mechanical vibrations, and improve the thermal efficiency. In addition, to facilitate the AM of the desired component and minimize the possible thermal distortion, the support structure for the AM is also designed with an optimized lattice structure.
The proposed design is initially validated through numerical simulations (structural, modal, and thermomechanical analysis), and virtual 3D CAD assembly. However, it is physically validated through prototyping and subsequent experimental tests. In addition, 3D scanning of the additively manufactured components is also performed through the reverse engineering technique of photogrammetry, as a quality check of the AM process.
In conclusion, the proposed design successfully supports up to three detector assemblies. It also reduced the structural weight, mechanical vibrations, and improved thermal efficiency, as warranted by the design requirements
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
Kepelbagaian ikan di Tasik Chini, Pahang, Malaysia
No full textKajian kepelbagaian dan penyebaran ikan di Tasik Chini telah dijalankan menggunakan jaring insang sebagai alat penangkapan. Sebanyak lapan stesen pensampelan telah dipilih (habitat berbeza) di seluruh tasik dan pensampelan telah dilakukan secara rawak di kawasan yang terpilih. Sejumlah 24 spesies ikan telah direkodkan yang terdiri daripada 944 ekor ikan. Kebanyakan ikan yang direkodkan adalah terdiri daripada famili Cyprinidae. Spesies dominan yang ditemui di Tasik Chini ialah loma (Thynnichthys thynnoides), cemperas (Cyclocheilichythys apogon) dan potok (Notopterus notopterus). Hasil ujian t-berpasangan menunjukkan terdapat perbezaan bermakna kepadatan ikan yang ditangkap di antara waktu siang dan waktu malam (p = 0.01, ? = 0.05) dan spesies pemangsa didapati paling dominan pada waktu malam. Kepelbagaian dan kepadatan ikan didapati lebih tinggi semasa pensampelan musim monsun yang dipercayai kesan daripada kemasukan ikan-ikan dari Sungai Pahang melalui Sungai Chini
Potensi chironomidae sebagai penunjuk biologi di sungai rekreasi terpilih Janda Baik, Pahang, Semenanjung Malaysia
No full textSatu kajian ke atas kepelbagaian chironomid (Diptera: Chironomidae) dalam ekosistem
bebas cemar telah dijalankan di Janda Baik, Pahang, Semenanjung Malaysia. Kajian ini
adalah untuk mengenalpasti penyebaran dan komposisi Chironomidae di tujuh sungai
rekreasi terpilih di Janda Baik. Chironomid disampel menggunakan jaring Surber dan enam
parameter kualiti air telah dianalisis iaitu oksigen terlarut (DO), permintaan oksigen
biokimia (BOD5), permintaan oksigen kimia (COD), ammoniakal nitrogen (NH3-N), jumlah
pepejal terampai (TSS) dan pH. Hasil kajian menunjukkan famili Chironomidae di Janda
Baik diwakili oleh tiga subfamili iaitu Chironominae, Orthocladiinae dan Tanypodinae
dengan jumlah individu sebanyak 10421. Chironominae dikenal pasti sebagai subfamili
yang paling dominan iaitu sejumlah 9168 individu, manakala subfamili Tanypodinae (849
individu) merupakan kedua tertinggi diikuti dengan Orthocladiinae (404 individu).
Polypedilum (Chironominae), Rheocricotopus (Orthocladiinae) dan Rheotanytarsus
(Chironominae) adalah genus yang dominan di Janda Baik. Polypedilum spp. mendominasi
enam daripada tujuh sungai kajian, manakala Rheocricotopus spp. didapati mendominasi
satu sungai iaitu Sg. Kerul. Ujian CCA memperlihatkan pengaruh kandungan DO yang kuat
dengan taburan Polypedilum dan potensinya untuk dijadikan sebagai penunjuk biologi untuk
sungai kelas II ke atas
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
