12,578 research outputs found
Meso-scale FDM material layout design strategies under manufacturability constraints and fracture conditions
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
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Ensuring Access to Safe and Nutritious Food for All Through the Transformation of Food Systems
A Spatio-temporal Decomposition Method for the Coordinated Economic Dispatch of Integrated Transmission and Distribution Grids
With numerous distributed energy resources (DERs) integrated into the
distribution networks (DNs), the coordinated economic dispatch (C-ED) is
essential for the integrated transmission and distribution grids. For large
scale power grids, the centralized C-ED meets high computational burden and
information privacy issues. To tackle these issues, this paper proposes a
spatio-temporal decomposition algorithm to solve the C-ED in a distributed and
parallel manner. In the temporal dimension, the multi-period economic dispatch
(ED) of transmission grid (TG) is decomposed to several subproblems by
introducing auxiliary variables and overlapping time intervals to deal with the
temporal coupling constraints. Besides, an accelerated alternative direction
method of multipliers (A-ADMM) based temporal decomposition algorithm with the
warm-start strategy, is developed to solve the ED subproblems of TG in
parallel. In the spatial dimension, a multi-parametric programming projection
based spatial decomposition algorithm is developed to coordinate the ED
problems of TG and DNs in a distributed manner. To further improve the
convergence performance of the spatial decomposition algorithm, the aggregate
equivalence approach is used for determining the feasible range of boundary
variables of TG and DNs. Moreover, we prove that the proposed spatio-temporal
decomposition method can obtain the optimal solution for bilevel convex
optimization problems with continuously differentiable objectives and
constraints. Numerical tests are conducted on three systems with different
scales, demonstrating the high computational efficiency and scalability of the
proposed spatio-temporal decomposition method
Évaluation de l'impact du changement climatique sur la défoliation de l'épinette noire par la tordeuse des bourgeons de l'épinette
Les modèles écologiques actuels prévoient de profonds effets des changements climatiques sur les régimes de perturbations naturelles des forêts. La tordeuse des bourgeons de l'épinette (Choristoneura fumiferana) (TBE) est le principal insecte défoliateur dans l'est de l'Amérique du Nord. Les épidémies de TBE ont un impact majeur sur la structure et la fonction de la forêt boréale canadienne puisque la défoliation entraîne une diminution de la croissance des arbres, une augmentation de la mortalité et une baisse de la productivité forestière. Les épidémies de TBE sont devenues plus sévères au cours du dernier siècle à cause des changements climatiques; cependant, nous savons peu de choses sur la manière dont l'effet intégré du climat et du TBE modifie la croissance des espèces hôtes. Nous évaluons ici comment l’interaction entre le climat et la gravité de l'épidémie affecte la croissance de l'épinette noire (Picea mariana) pendant l'épidémie de TBE qui a eu lieu entre 1968-1988 et 2006-2017. Nous avons compilé des séries dendrochronologiques (2271 arbres), des données de sévérité de l'épidémie (estimée par la défoliation aérienne observée) et des données climatiques pour 164 sites au Québec, Canada. Nous avons utilisé un modèle linéaire à effets mixtes pour déterminer l'impact des paramètres climatiques, de la défoliation cumulative (des cinq années précédentes) et de leur effet couplé sur la croissance en surface terrière. À la gravité maximale de l'épidémie, la croissance en surface terrière de l'épinette noire a été réduite de 14 à 18 % sur les cinq années en raison de l'effet TBE. Cette croissance a été affectée par le climat : des températures minimales estivales précédentes plus élevées et un indice d'humidité climatique estival plus élevé ont réduit la croissance de 11 % et 4 % respectivement. En revanche, l'effet négatif de la défoliation a été atténué de 9% pour une température minimale plus élevée au printemps précédent et de 7% pour une température maximale plus élevée l'été précédent. Cette étude améliore notre compréhension des effets combinés de la TBE et du climat et aide à prévoir les dommages futurs causés par cet insecte dans les peuplements forestiers afin de soutenir la gestion durable des forêts. Nous recommandons également que les projections des écosystèmes dans la forêt boréale incluent plusieurs classes de défoliation de la TBE et plusieurs scénarios climatiques
Neural Architecture Search: Insights from 1000 Papers
In the past decade, advances in deep learning have resulted in breakthroughs
in a variety of areas, including computer vision, natural language
understanding, speech recognition, and reinforcement learning. Specialized,
high-performing neural architectures are crucial to the success of deep
learning in these areas. Neural architecture search (NAS), the process of
automating the design of neural architectures for a given task, is an
inevitable next step in automating machine learning and has already outpaced
the best human-designed architectures on many tasks. In the past few years,
research in NAS has been progressing rapidly, with over 1000 papers released
since 2020 (Deng and Lindauer, 2021). In this survey, we provide an organized
and comprehensive guide to neural architecture search. We give a taxonomy of
search spaces, algorithms, and speedup techniques, and we discuss resources
such as benchmarks, best practices, other surveys, and open-source libraries
Norsk rå kumelk, en kilde til zoonotiske patogener?
The worldwide emerging trend of eating “natural” foods, that has not been
processed, also applies for beverages. According to Norwegian legislation, all
milk must be pasteurized before commercial sale but drinking milk that has
not been heat-treated, is gaining increasing popularity. Scientist are warning
against this trend and highlights the risk of contracting disease from milkborne
microorganisms. To examine potential risks associated with drinking
unpasteurized milk in Norway, milk- and environmental samples were
collected from dairy farms located in south-east of Norway. The samples
were analyzed for the presence of specific zoonotic pathogens; Listeria
monocytogenes, Campylobacter spp., and Shiga toxin-producing Escherichia
coli (STEC). Cattle are known to be healthy carriers of these pathogens, and
Campylobacter spp. and STEC have a low infectious dose, meaning that
infection can be established by ingesting a low number of bacterial cells. L.
monocytogenes causes one of the most severe foodborne zoonotic diseases,
listeriosis, that has a high fatality rate. All three pathogens have caused milk
borne disease outbreaks all over the world, also in Norway.
During this work, we observed that the prevalence of the three examined
bacteria were high in the environment at the examined farms. In addition, 7%
of the milk filters were contaminated by STEC, 13% by L. monocytogenes and
4% by Campylobacter spp. Four of the STEC isolates detected were eaepositive,
which is associated with the capability to cause severe human
disease. One of the eae-positive STEC isolates were collected from a milk
filter, which strongly indicate that Norwegian raw milk may contain potential
pathogenic STEC.
To further assess the possibilities of getting ill by STEC after consuming raw
milk, we examined the growth of the four eae-positive STEC isolates in raw milk at different temperatures. All four isolates seemed to have ability to multiply in raw milk at 8°C, and one isolate had significant growth after 72 hours. Incubation at 6°C seemed to reduce the number of bacteria during the
first 24 hours before cell death stopped. These findings highlight the
importance of stable refrigerator temperatures, preferable < 4°C, for storage
of raw milk.
The L. monocytogenes isolates collected during this study show genetic
similarities to isolates collected from urban and rural environmental
locations, but different clones were predominant in agricultural
environments compared to clinical and food environments. However, the
results indicate that the same clone can persist in a farm over time, and that
milk can be contaminated by L. monocytogenes clones present in farm
environment.
Despite testing small volumes (25 mL) of milk, we were able to isolate both
STEC and Campylobacter spp. directly from raw milk. A proportion of 3% of
the bulk tank milk and teat milk samples were contaminated by
Campylobacter spp. and one STEC was isolated from bulk tank milk. L
monocytogenes was not detected in bulk tank milk, nor in teat milk samples.
The agricultural evolvement during the past decades have led to larger
production units and new food safety challenges. Dairy cattle production in
Norway is in a current transition from tie-stall housing with conventional
pipeline milking systems, to modern loose housing systems with robotic
milking. The occurrence of the three pathogens in this project were higher in
samples collected from farms with loose housing compared to those with tiestall
housing.
Pasteurization of cow’s milk is a risk reducing procedure to protect
consumers from microbial pathogens and in most EU countries, commercial
distribution of unpasteurized milk is legally restricted. Together, the results
presented in this thesis show that the animal housing may influence the level
of pathogenic bacteria in the raw milk and that ingestion of Norwegian raw
cow’s milk may expose consumers to pathogenic bacteria which can cause
severe disease, especially in children, elderly and in persons with underlying
diseases. The results also highlight the importance of storing raw milk at low
temperatures between milking and consumption.Å spise mat som er mindre prosessert og mer «naturlig» er en pågående
trend i Norge og i andre deler av verden. Interessen for å drikke melk som
ikke er varmebehandlet, såkalt rå melk, er også økende. I Norge er det påbudt
å pasteurisere melk før kommersielt salg for å beskytte forbrukeren mot
sykdomsfremkallende mikroorganismer. Fagfolk advarer mot å drikke rå
melk, og påpeker risikoen for å bli syk av patogene bakterier som kan finnes i
melken.
I denne avhandlingen undersøker vi den potensielle risikoen det medfører å
drikke upasteurisert melk fra Norge. I tillegg til å samle inn tankmelk- og
speneprøver fra melkegårder i sørøst Norge, samlet vi også miljøprøver fra
de samme gårdene for å kartlegge forekomst og for å identifisere potensielle
mattrygghetsrisikoer i melkeproduksjonen. Alle prøvene ble analysert for de
zoonotiske sykdomsfremkallende bakteriene Listeria monocytogenes,
Campylobacter spp., og Shiga toksin-produserende Escherichia coli (STEC).
Kyr kan være friske smittebærere av disse bakteriene, som dermed kan
etablere et reservoar på gårdene. Bakteriene kan overføres fra gårdsmiljøet
til melkekjeden og dermed utfordre mattryggheten. Disse bakteriene har
forårsaket melkebårne sykdomsutbrudd over hele verden, også i Norge.
Campylobacter spp. og STEC har lav infeksiøs dose, som vil si at man kan bli
syk selv om man bare inntar et lavt antall bakterieceller. L. monocytogenes
kan gi sykdommen listeriose, en av de mest alvorlige matbårne zoonotiske
sykdommene vi har i den vestlige verden.
Resultater fra denne oppgaven viser en høy forekomst av de tre patogenene i
gårdsmiljøet. I tillegg var 7% av melkefiltrene vi testet positive for STEC, 13%
positive for L. monocytogenes og 4% positive for Campylobacter spp.. Fire av
STEC isolatene bar genet for Intimin, eae, som er ansett som en viktig
virulensfaktor som øker sjansen for alvorlig sykdom. Ett av de eae-positive
isolatene ble funnet i et melkefilter, noe som indikerer at norsk rå melk kan
inneholde patogene STEC. For å videre vurdere risikoen for å bli syk av STEC
fra rå melk undersøkte vi hvordan de fire eae-positive isolatene vokste i rå
melk lagret ved forskjellige temperaturer. For alle isolatene økte antall
bakterier etter lagring ved 8°C, og for et isolat var veksten signifikant. Etter
lagring ved 6°C ble antallet bakterier redusert de første 24 timene, deretter
stoppet reduksjonen i antall bakterier. Disse resultatene viser hvor viktig det
er å ha stabil lav lagringstemperatur for rå melk, helst < 4°C.
L. monocytogenes isolatene som ble samlet inn fra melkegårdene viste
genetiske likheter med isolater samlet inn fra urbane og rurale miljøer rundt
omkring i Norge. Derimot var kloner som dominerte i landbruksmiljøet
forskjellige fra kliniske isolater og isolater fra matproduksjonslokaler. Videre
så man at en klone kan persistere på en gård over tid og at melk kan
kontamineres av L. monocytogenes kloner som er til stede i gårdsmiljøet.
Til tross for små testvolum av tankmelken (25 mL) fant vi både STEC og
Campylobacter spp. i melkeprøvene. 3% av tankmelkprøvene og
speneprøvene var positive for Campylobacter spp. og ett STEC isolat ble
funnet i tankmelk. L. monocytogenes ble ikke funnet direkte i melkeprøvene.
Landbruket i Norge er i stadig utvikling der besetningene blir større, men
færre. Melkebesetningene er midt i en overgang der tradisjonell oppstalling
med melking på bås byttes ut med løsdriftssystemer og melkeroboter.
Forekomsten av de tre patogenene funnet i denne studien var høyere i
besetningene med løsdrift sammenliknet med besetningene som hadde
melkekyrne oppstallet på bås.
Pasteurisering er et viktig forebyggende tiltak for å beskytte konsumenter fra
mikrobielle patogener, og i de fleste EU-land er kommersielt salg av rå melk
juridisk begrenset. Denne studien viser at oppstallingstype kan påvirke
nivåene av patogene bakterier i gårdsmiljøet og i rå melk. Inntak av rå melk
kan eksponere forbruker for patogene bakterier som kan gi alvorlig sykdom,
spesielt hos barn, eldre og personer med underliggende sykdommer.
Resultatene underbygger viktigheten av å pasteurisere melk for å sikre
mattryggheten, og at det er avgjørende å lagre rå melk ved kontinuerlig lave
temperaturer for å forebygge vekst av zoonotiske patogener
Anuário científico da Escola Superior de Tecnologia da Saúde de Lisboa - 2021
É com grande prazer que apresentamos a mais recente edição (a 11.ª) do Anuário Científico da Escola Superior de Tecnologia da Saúde de Lisboa. Como instituição de ensino superior, temos o compromisso de promover e incentivar a pesquisa científica em todas as áreas do conhecimento que contemplam a nossa missão. Esta publicação tem como objetivo divulgar toda a produção científica desenvolvida pelos Professores, Investigadores, Estudantes e Pessoal não Docente da ESTeSL durante 2021. Este Anuário é, assim, o reflexo do trabalho árduo e dedicado da nossa comunidade, que se empenhou na produção de conteúdo científico de elevada qualidade e partilhada com a Sociedade na forma de livros, capítulos de livros, artigos publicados em revistas nacionais e internacionais, resumos de comunicações orais e pósteres, bem como resultado dos trabalhos de 1º e 2º ciclo. Com isto, o conteúdo desta publicação abrange uma ampla variedade de tópicos, desde temas mais fundamentais até estudos de aplicação prática em contextos específicos de Saúde, refletindo desta forma a pluralidade e diversidade de áreas que definem, e tornam única, a ESTeSL. Acreditamos que a investigação e pesquisa científica é um eixo fundamental para o desenvolvimento da sociedade e é por isso que incentivamos os nossos estudantes a envolverem-se em atividades de pesquisa e prática baseada na evidência desde o início dos seus estudos na ESTeSL. Esta publicação é um exemplo do sucesso desses esforços, sendo a maior de sempre, o que faz com que estejamos muito orgulhosos em partilhar os resultados e descobertas dos nossos investigadores com a comunidade científica e o público em geral. Esperamos que este Anuário inspire e motive outros estudantes, profissionais de saúde, professores e outros colaboradores a continuarem a explorar novas ideias e contribuir para o avanço da ciência e da tecnologia no corpo de conhecimento próprio das áreas que compõe a ESTeSL. Agradecemos a todos os envolvidos na produção deste anuário e desejamos uma leitura inspiradora e agradável.info:eu-repo/semantics/publishedVersio
Procedural Generation of Complex Roundabouts for Autonomous Vehicle Testing
High-definition roads are an essential component of realistic driving
scenario simulation for autonomous vehicle testing. Roundabouts are one of the
key road segments that have not been thoroughly investigated. Based on the
geometric constraints of the nearby road structure, this work presents a novel
method for procedurally building roundabouts. The suggested method can result
in roundabout lanes that are not perfectly circular and resemble real-world
roundabouts by allowing approaching roadways to be connected to a roundabout at
any angle. One can easily incorporate the roundabout in their HD road
generation process or use the standalone roundabouts in scenario-based testing
of autonomous driving
A generalised multi-factor deep learning electricity load forecasting model for wildfire-prone areas
This paper proposes a generalised and robust multi-factor Gated Recurrent
Unit (GRU) based Deep Learning (DL) model to forecast electricity load in
distribution networks during wildfire seasons. The flexible modelling methods
consider data input structure, calendar effects and correlation-based leading
temperature conditions. Compared to the regular use of instantaneous
temperature, the Mean Absolute Percentage Error (MAPE) is decreased by 30.73%
by using the proposed input feature selection and leading temperature
relationships. Our model is generalised and applied to eight real distribution
networks in Victoria, Australia, during the wildfire seasons of 2015-2020. We
demonstrate that the GRU-based model consistently outperforms another DL model,
Long Short-Term Memory (LSTM), at every step, giving average improvements in
Mean Squared Error (MSE) and MAPE of 10.06% and 12.86%, respectively. The
sensitivity to large-scale climate variability in training data sets, e.g. El
Ni\~no or La Ni\~na years, is considered to understand the possible
consequences for load forecasting performance stability, showing minimal
impact. Other factors such as regional poverty rate and large-scale off-peak
electricity use are potential factors to further improve forecast performance.
The proposed method achieves an average forecast MAPE of around 3%, giving a
potential annual energy saving of AU\$80.46 million for the state of Victoria
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