13,086 research outputs found

    Meso-scale FDM material layout design strategies under manufacturability constraints and fracture conditions

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    In the manufacturability-driven design (MDD) perspective, manufacturability of the product or system is the most important of the design requirements. In addition to being able to ensure that complex designs (e.g., topology optimization) are manufacturable with a given process or process family, MDD also helps mechanical designers to take advantage of unique process-material effects generated during manufacturing. One of the most recognizable examples of this comes from the scanning-type family of additive manufacturing (AM) processes; the most notable and familiar member of this family is the fused deposition modeling (FDM) or fused filament fabrication (FFF) process. This process works by selectively depositing uniform, approximately isotropic beads or elements of molten thermoplastic material (typically structural engineering plastics) in a series of pre-specified traces to build each layer of the part. There are many interesting 2-D and 3-D mechanical design problems that can be explored by designing the layout of these elements. The resulting structured, hierarchical material (which is both manufacturable and customized layer-by-layer within the limits of the process and material) can be defined as a manufacturing process-driven structured material (MPDSM). This dissertation explores several practical methods for designing these element layouts for 2-D and 3-D meso-scale mechanical problems, focusing ultimately on design-for-fracture. Three different fracture conditions are explored: (1) cases where a crack must be prevented or stopped, (2) cases where the crack must be encouraged or accelerated, and (3) cases where cracks must grow in a simple pre-determined pattern. Several new design tools, including a mapping method for the FDM manufacturability constraints, three major literature reviews, the collection, organization, and analysis of several large (qualitative and quantitative) multi-scale datasets on the fracture behavior of FDM-processed materials, some new experimental equipment, and the refinement of a fast and simple g-code generator based on commercially-available software, were developed and refined to support the design of MPDSMs under fracture conditions. The refined design method and rules were experimentally validated using a series of case studies (involving both design and physical testing of the designs) at the end of the dissertation. Finally, a simple design guide for practicing engineers who are not experts in advanced solid mechanics nor process-tailored materials was developed from the results of this project.U of I OnlyAuthor's request

    The growclusters Package for R

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    The growclusters package for R implements an enhanced version of k-means clustering that allows discovery of local clusterings or partitions for a collection of data sets that each draw their cluster means from a single, global partition. The package contains functions to estimate a partition structure for multivariate data. Estimation is performed under a penalized optimization derived from Bayesian non-parametric formulations. This paper describes some of the functions and capabilities of the growclusters package, including the creation of R Shiny applications designed to visually illustrate the operation and functionality of the growclusters package.Comment: 10 pages, 6 figures, paper presented at 2022 Joint Statistical Meeting

    Identifizierung prädiktiver und prognostischer Biomarker in unterschiedlichen Tumorkompartimenten des ösophagealen Adenokarzinoms

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    Das ösophageale Adenokarzinom zeigt eine global steigende Inzidenz und hat mit einer 5-Jahres-Überlebensrate von weniger als 25% eine schlechte Prognose. Personalisierte Therapieansätze sind selten und prognostische/prädiktive Biomarker des Tumormikromilieus sind unzureichend charakterisiert. Die kumulative Promotion nähert sich dieser Problematik in drei unterschiedlichen Schwerpunkten. 1. Zur Identifizierung Kompartiment-spezifischer Biomarker wurde eine Methode entwickelt, welche als kostengünstige Alternative zum sc-Seq Expressionsprofile individueller Zelltypen generiert. Dabei erfolgt die Extraktion der RNA nicht aus Einzelzellen, sondern aus flowzytometrisch-getrennten Zellkompartimenten. Die Separation der Proben in Epithelzellen, Immunzellen und Fibroblasten wurde durch verschiedene Verfahren validiert und eine suffiziente Ausbeute an RNA auch für kleine Gewebemengen gezeigt. 2. Biomarker des Immunzellkompartiments als therapeutische Angriffspunkte wurden in einem Patientenkollektiv von bis zu 551 Patienten auf ihre Bedeutung beim EAC überprüft. Es zeigte sich eine Expression der Immuncheckpoints LAG3, VISTA und IDO auf TILs durch IHC und RNA-Sonden basierte Verfahren in einem relevanten Anteil (LAG3: 11,4%, VISTA: 29%, IDO: 52,6%). Es konnte eine prognostisch günstige Bedeutung der VISTA, LAG3 und IDO Expression gezeigt werden. Durch den Vergleich von Genexpressionsprofilen aus therapienaiven und vorbehandelten Tumoren konnte zudem ein immunsuppressiver Effekt von neoadjuvanten Therapiekonzepten auf das Tumormikromilieu des EACs gezeigt werden. Dabei kam es zur verminderten Expression von Checkpoints und Anzahl TILs nach (Radio-) Chemotherapie. 3. Im Tumorzellkompartiment wurde die Rolle von Amplifikationen in ErbB-Rezeptor abhängigen Signalwegen durch FISH-Technik und Immunhistochemie evaluiert. Es fanden sich KRAS Amplifikationen in 17,1%, PIK3CA Amplifikationen in 5% sowie eine HER2/neu-Überexpression in 14,9% der untersuchten Tumore

    Countermeasures for the majority attack in blockchain distributed systems

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    La tecnología Blockchain es considerada como uno de los paradigmas informáticos más importantes posterior al Internet; en función a sus características únicas que la hacen ideal para registrar, verificar y administrar información de diferentes transacciones. A pesar de esto, Blockchain se enfrenta a diferentes problemas de seguridad, siendo el ataque del 51% o ataque mayoritario uno de los más importantes. Este consiste en que uno o más mineros tomen el control de al menos el 51% del Hash extraído o del cómputo en una red; de modo que un minero puede manipular y modificar arbitrariamente la información registrada en esta tecnología. Este trabajo se enfocó en diseñar e implementar estrategias de detección y mitigación de ataques mayoritarios (51% de ataque) en un sistema distribuido Blockchain, a partir de la caracterización del comportamiento de los mineros. Para lograr esto, se analizó y evaluó el Hash Rate / Share de los mineros de Bitcoin y Crypto Ethereum, seguido del diseño e implementación de un protocolo de consenso para controlar el poder de cómputo de los mineros. Posteriormente, se realizó la exploración y evaluación de modelos de Machine Learning para detectar software malicioso de tipo Cryptojacking.DoctoradoDoctor en Ingeniería de Sistemas y Computació

    Perfect is the enemy of test oracle

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    Automation of test oracles is one of the most challenging facets of software testing, but remains comparatively less addressed compared to automated test input generation. Test oracles rely on a ground-truth that can distinguish between the correct and buggy behavior to determine whether a test fails (detects a bug) or passes. What makes the oracle problem challenging and undecidable is the assumption that the ground-truth should know the exact expected, correct, or buggy behavior. However, we argue that one can still build an accurate oracle without knowing the exact correct or buggy behavior, but how these two might differ. This paper presents SEER, a learning-based approach that in the absence of test assertions or other types of oracle, can determine whether a unit test passes or fails on a given method under test (MUT). To build the ground-truth, SEER jointly embeds unit tests and the implementation of MUTs into a unified vector space, in such a way that the neural representation of tests are similar to that of MUTs they pass on them, but dissimilar to MUTs they fail on them. The classifier built on top of this vector representation serves as the oracle to generate "fail" labels, when test inputs detect a bug in MUT or "pass" labels, otherwise. Our extensive experiments on applying SEER to more than 5K unit tests from a diverse set of open-source Java projects show that the produced oracle is (1) effective in predicting the fail or pass labels, achieving an overall accuracy, precision, recall, and F1 measure of 93%, 86%, 94%, and 90%, (2) generalizable, predicting the labels for the unit test of projects that were not in training or validation set with negligible performance drop, and (3) efficient, detecting the existence of bugs in only 6.5 milliseconds on average.Comment: Published in ESEC/FSE 202

    Genome-wide analysis emancipates genomic diversity and signature of selection in Altay white-headed cattle of Xinjiang, China

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    Altay white-headed cattle have not received enough attention for several reasons. Due to irrational breeding and selection practices, the number of pure Altay white-headed cattle has decreased significantly and the breed is now on the eve of extinction. The genomic characterization will be a crucial step towards understanding the genetic basis of productivity and adaptability to survival under native Chinese agropastoral systems; nevertheless, no attempt has been made in Altay white-headed cattle. In the current study, we compared the genomes of 20 Altay white-headed cattle to the genomes of 144 individuals in representative breeds. Population genetic diversity revealed that the nucleotide diversity of Altay white-headed cattle was less than that of indicine breeds and comparable to that of Chinese taurus cattle. Using population structure analysis, we also found that Altay white-headed cattle carried the ancestry of the European and East Asian cattle lineage. In addition, we used three different methods (FST, θπ ratio and XP-EHH) to investigate the adaptability and white-headed phenotype of Altay white-headed cattle and compared it with Bohai black cattle. We found EPB41L5, SCG5 and KIT genes on the list of the top one percent genes, these genes might have an association with environmental adaptability and the white-headed phenotype for this breed. Our research reveals the distinctive genomic features of Altay white-headed cattle at the genome-wide level

    Valores Públicos e Performance Financeira das Entidades Públicas: Proposta de Modelo de Análise na Perspetiva do Relato

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    Tese de Doutoramento em Administração Pública Especialização em Administração e Políticas PúblicasA criação de valor público, na qual a Administração Pública assume um papel fundamental, deverá traduzir o interesse dos cidadãos e nortear-se por um conjunto abrangente de valores públicos. Estes valores públicos, amplos, complexos e divergentes, devem integrar o modelo de governança democrática, suportar a tomada de decisão e servir de referência para a Administração Pública, na prossecução do interesse público. Tendo por base os modelos de governação pública, a Teoria do Valor Público e a Teoria do Interesse Público, bem como as dimensões dos valores públicos apontadas por stakeholders e influencers da informação financeira pública, procurou estudar-se de que forma os valores públicos, que materializam o interesse público, podem integrar na sua função de accountability, a avaliação e a análise da performance financeira na perspetiva da prestação de contas das entidades públicas. Nesse sentido, o estudo pretendeu identificar quais os valores públicos de natureza económica e financeira que interessam aos stakeholders e enquadrá-los num modelo estruturado de análise da financeira, que contribua para o reforço da performance accountability e transparência do relato financeiro público. A partir de uma estratégia de investigação mista, materializada na realização de entrevistas semiestruturadas e no ensaio aplicado sobre os dados financeiros do Município de Cascais, a investigação desenvolveu um modelo de análise e relato da performance financeira com vista a integrar a prestação de contas das entidades públicas, tendo como referência basilar não a ótica contabilística da estrutura e conteúdo das demonstrações financeiras, mas os «valores públicos» que consubstanciam o «interesse público». Conclui-se que este modelo favorece a adequação do relato financeiro público aos valores públicos, bem como representa um contributo para a normalização da avaliação da performance, reduzindo a discricionariedade do relato, melhorando o benchmarking financeiro e o robustecimento do sistema de avaliação do desempenho das entidades públicas previsto na Lei de Enquadramento Orçamental.The creation of public value, in which the Public Administration plays a key role, should translate the citizens' interest and be guided by a comprehensive set of public values. These public values, broad, complex and divergent, should integrate the democratic governance model, support decision-making, and serve as a reference for the Public Administration in the pursuit of public interest. Based on the models of public governance, the Public Interest Theory and the Theory of Public Values, as well as the dimensions of public values pointed out by stakeholders and influencers of public financial information, we sought to study how public values, which materialize public interest, can integrate into the function of accountability, the evaluation and analysis of financial performance from the perspective of accountability of public entities. In this sense, the study intended to identify which public values of economic and financial nature are of interest to the stakeholders and frame them in a structured model of financial performance analysis, which contributes to the strengthening of accountability and transparency of public financial reporting. Based on a mixed research strategy, materialized in semi-structured interviews and the test applied on the financial data of the Municipality of Cascais, the research developed a model of analysis and reporting of the financial performance to integrate the accountability of public entities. This was done having as an essential reference not the accounting perspective of the structure and content of the financial statements, but the "public values" that embody the "public interest". The conclusion is that this model favours the adequacy of public financial reporting to public values and represents a contribution to the standardization of performance evaluation, reducing the discretion of reporting, improving financial benchmarking, and strengthening the performance evaluation system of public entities foreseen in the Budgetary Framework Law.N/

    Brand logos versus brand names: A comparison of the memory effects of textual and pictorial brand elements placed in computer games

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    While a plethora of studies on gamification of advertising exists, little is known about how consumers process different types of brand elements (logos and names) placed in computer games, and whether differences in information processing lead to variations in brand memory. This gap is addressed by conducting three rigorous experiments. In Study 2 we find that, in general, brand logos lead to stronger memory than brand names – something known as the picture superiority effect. Study 3 examines the condition where the picture superiority effect is neutralized. We find that when the speed of a computer game is reduced, names and logos develop similar memory. Finally, in Study 4, we examine whether the picture superiority effect can be neutralized also in the context of high-speed games. We find that in fast games if the physical distinctiveness of the brand elements is increased, both logos and names yield in similar memory

    Dialogical arts through sustainable communities: acting on the margins, redefining empowerment

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