1,722,963 research outputs found
Geochemical modeling of soil-binder systems in stabilization/solidification applications
Get PDFLa gestione sostenibile del suolo rappresenta la condizione primaria per garantire l’equilibrio degli ecosistemi terrestri e i cicli geochimici. La crescente urbanizzazione degli ultimi decenni ha portato alla produzione di enormi volumi di rifiuti solidi in tutto il mondo, particolarmente dannosi per la salute umana, della fauna e della flora circostante. Il processo di solidificazione/stabilizzazione in situ (S/S) è stata proposto come strategia di bonifica sostenibile al fine di prevenire la mobilizzazione degli inquinanti in siti contaminati. Di contro le problematiche legate all’utilizzo di cemento Portland (OPC), che rappresenta il legante idraulico più utilizzato nella tecnica S/S, quali elevate emissioni di CO2 durante la sua produzione e la sua durabilità rappresentano un grande limite all’utilizzo di questa strategia di bonifica. In questo lavoro, è stata investigata la possibilità di superare queste problematiche riducendo al massimo l’utilizzo di OPC nel processo S/S nella bonifica di due rifiuti solidi particolarmente inquinati quali ceneri di pirite e fosfogesso ovvero i principali scarti di produzione dell'industria dei concimi fostatici. Nel processo di bonifica sono stati quindi investigati parallelamente il legante tradizionale (OPC) e cinque leganti alternativi a bassa impronta di CO2 (cemento alluminoso, mayenite miscelata con loppa d'altoforno, loppa d'altoforno ad attivazione alcalina, un cemento di tipo III/B e γ-Al2O3). Il lavoro ha previsto una preliminare caratterizzazione fisico-chimica dei leganti idraulici e delle miscele legante idraulico/suolo inquinato ed una successivo modeling geochimico con il fine di identificare e quantificare i meccanismi di ritenzione dei contaminanti e garantire un riciclo del rifiuto solido efficace e sostenibile nel tempo. Infine, è stata eseguita una valutazione preliminare dell'integrazione di queste tecnologie innovative di bonifica accoppiata ad una alta efficienza di bonifica con contemporanea riduzione delle emissioni di gas serra e offrendo allo stesso tempo vantaggi tecnici nelle bonifiche di grandi volumi di rifiuti solidi. I risultati complessivi del lavoro hanno permesso l’identificazione dei principali meccanismi di immobilizzazione degli inquinanti e il loro grado di efficienza, ed hanno evidenziato come un approccio “CO2 free” sia urgente per garantire la sostenibilità di tecnologie S/S. La modellazione geochimica costruita sulla base delle caratteristiche dei rifiuti solidi rappresenta uno step fondamentale per prevedere l’applicabilità ed efficienza delle diverse strategie di bonifica disponibili in termini di sostenibilità ambientale ed economica a lungo termine.Sustainable soil stewardship provides the basis for terrestrial ecosystems and geochemical cycles. However, the unprecedented urbanization in the last decades brought massive solid waste stockpiles worldwide, detrimental to soil health and the neighborhood flora and fauna. Herein, in-situ solidification/stabilization (S/S) has been proposed as a remediation strategy to prevent further pollution in the contaminated sites. But the challenges of substantial CO2 emission and the sensitive durability attributed to the ordinary Portland cement (OPC), which is the most widely used binder in the S/S technique, place this strategy under scrutiny.
In this work, we examined the feasibility of mitigating or negating the use of OPC in the S/S process of pyrite ash and phosphogypsum, the primary hazardous solid wastes generated in the phosphate industry. One traditional binder (OPC) and five alternative low-carbon footprint binders (calcium aluminate cement, mayenite mixed with blast furnace slag, alkaline-activated blast furnace slag, commercial CEMENT III/B, and γ-Al2O3) were applied in the remediation process. After the physicochemical and mineralogical characterization of the stabilized products, we constructed the geochemical modeling to reveal the potential mechanisms of contaminant retention and ensure long-term environmental availability. Finally, we evaluated how integrating these innovative technologies could shed light on reducing greenhouse gas emissions and offer technical benefits in future field trials. The overall findings underscore the immobilization mechanisms of pollutants using different binder strategies and highlight the urgent need to bridge the zero-emission insights to sustainable S/S technologies. The constructed geochemical modeling, in tandem with the inclusion of more solid waste types and properties in the following models, will be pivotal in predicting the availability and efficiency of green and sustainable remediation strategies
A recursive design method for heat exchanger networks / by Yikai Ren.
No full textLast leaf includes a list of publications co-authored by the author during the preparation of this thesis.Includes bibliographical references (leaves 179-187).xiv, 188 leaves : ill. ; 30 cm.A novel and reliable method for heat exchanger network synthesis is proposed.The prime objective has been the elimination or reduction of drawbacks inherent in both evolutionary methods and mathematical programming methods while retaining the adevantages of both methods.Thesis (Ph.D.)--Adelaide University, Dept. of Chemical Engineering, 200
Theoretical study on the interfacial instability of a spherical droplet subject to vertical vibration
No full textInterfacial instability would be aroused on a spherical liquid droplet when it is subject to external vertical vibration. In this paper, a linear analysis was conducted on this instability problem. The polar-angle dependent acceleration in the spherical coordinate is strongly coupled with the temporal and spatial component of the surface deformation displacement, which gives a recursion equation that implicitly expresses the dispersion relation between the growth rate and the spherical mode numbers. The unstable regions (or unstable tongues) for the inviscid fluids considering the latitudinal mode (longitudinal mode number m = 0) were derived and presented in the parameter space. Compared to the solution of the spherical Faraday instability under radial vibration acceleration, the regions of harmonic unstable tongues for the mono-directional vibration cases become much narrower, and the subharmonic unstable tongues almost approach straight lines. The analysis shows that the latitudinal waves emerging on the spherical droplet surface ought to oscillate harmonically instead of subharmonically, which is opposite to the results for the case under radial vibration acceleration. A corresponding experiment of a liquid droplet lying on a vertically vibrating plate was conducted, and the observations substantiate our theoretical predictions
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Towards Context-Stable and Visual-Consistent Image Inpainting
Get PDFRecent progress in inpainting increasingly relies on generative models,
leveraging their strong generation capabilities for addressing large irregular
masks. However, this enhanced generation often introduces context-instability,
leading to arbitrary object generation within masked regions. This paper
proposes a balanced solution, emphasizing the importance of unmasked regions in
guiding inpainting while preserving generation capacity. Our approach, Aligned
Stable Inpainting with UnKnown Areas Prior (ASUKA), employs a Masked
Auto-Encoder (MAE) to produce reconstruction-based prior. Aligned with the
powerful Stable Diffusion inpainting model (SD), ASUKA significantly improves
context stability. ASUKA further adopts an inpainting-specialized decoder,
highly reducing the color inconsistency issue of SD and thus ensuring more
visual-consistent inpainting. We validate effectiveness of inpainting
algorithms on benchmark dataset Places 2 and a collection of several existing
datasets, dubbed MISATO, across diverse domains and masking scenarios. Results
on these benchmark datasets confirm ASUKA's efficacy in both context-stability
and visual-consistency compared to SD and other inpainting algorithms.Comment: Project page: https://yikai-wang.github.io/asuka/ where full-size PDF
with appendix is available. Dataset:
https://github.com/Yikai-Wang/asuka-misato. Yikai Wang and Chenjie Cao
contribute equall
Variations on the Author
Get PDF“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
Get PDFWe 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
Network-based characterization of brain functional connectivity in Zen practitioners
No full textIn the last decade, a number of neuroimaging studies have investigated the neurophysiological effects associated with contemplative practices. Meditation-related changes in resting state functional connectivity (rsFC) have been previously reported, particularly in the default mode network, frontoparietal (FP) attentional circuits, saliency-related regions, and primary sensory cortices. We collected fMRI data from a sample of 12 experienced Zen meditators and 12 meditation-naïve matched controls during a basic attention-to-breathing protocol, together with behavioral performance outside the scanner on a set of computerized neuropsychological tests. We adopted a network system of 209 nodes, classified into 9 functional modules, and a multi-stage approach to identify rsFC differences in meditators and controls. Between-group comparisons of modulewise FC, summarized by the first principal component of the relevant set of edges, revealed important connections of FP circuits with early visual and executive control areas. We also identified several group differences in positive and negative edgewise FC, often involving the visual or FP regions. Multivariate pattern analysis of modulewise FC, using Support Vector Machine (SVM), classified meditators and controls with 79% accuracy and selected 10 modulewise connections that were jointly prominent in distinguishing meditators and controls; a similar SVM procedure based on the subjects' scores on the neuropsychological battery yielded a slightly weaker accuracy (75%). Finally, we observed a good correlation between the across-subject variation in strength of modulewise connections among FP, executive, and visual circuits, on the one hand, and in the performance on a rapid visual information processing (RVIP) test of sustained attention, on the other. Taken together, these findings highlight the usefulness of employing network analysis techniques in investigating the neural correlates of contemplative practices
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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