SOLUTION PROCESSING OF STRIPES, PATCHES AND DIGITAL PATTERNS USING A NOVEL SLOT DIE COATING-INSPIRED APPROACH

In recent decades, printing and coating techniques have received interest for manufacturing of low-cost wearable electronics, sensors, displays, photovoltaics, and energy storage devices. The functionality of these devices depends significantly on the print resolution, with typical feature sizes ranging from millimeters to microns. Although feature sizes across this range are technically feasible with established techniques, processing at commercial scale has emerged as a persistent modern challenge. To address this challenge, this dissertation develops an approach that combines the wide-area advantages of slot die coating with a sophisticated patterning capability. Experimental and analytical investigations are carried out to evaluate the pattern complexity and minimum feature size achievable with this approach, to determine the coupling between process parameters and pattern output, and to establish constraints on material formulation that are unique to the process. The first investigation explores the role of wetting and spreading in a narrow coating bead as phenomena that mediate pattern output. The second investigation considers co-deposition of two materials to form alternating continuous stripes in a single processing step. Finally, co-laminar internal flow of two materials is investigated as a mechanism for reducing feature size and manipulating pattern morphology. Using this approach, fine-pitch features smaller than 50 µm are demonstrated in a wide-area coating process with commercially available conductive inks.Ph.D

Advancements in the Measurement of the Cryosphere Using Geophysics — Introduction

Frozen regions of the earth are known as the cryosphere. The arctic, Antarctica, permafrost, ice sheets, and glaciers are some of the most challenging places to measure subsurface parameters, but they can also be some of the most important places to science and engineering research due to their susceptibility to environmental change. Ground-based, airborne, and space-borne geophysical methods are deployed to observe targets below the ground or in ice that may be difficult or impossible to measure using conventional direct observations and measurements. The papers in this special section address recent advances in instrumentation development and deployment and computational capabilities that have advanced cryosphere geophysical sciences. As such, many of these papers discuss the science that the methodology has helped reveal

Alvenaria participante em pórtico de concreto pré-moldado

O presente trabalho apresenta estudo sobre alvenaria estrutural construída dentro de pórticos em concreto pré-moldado dimensionada como parte do sistema de contraventamento das edificações, definindo esse tipo de elemento como Alvenaria Participante. São identificados os principais detalhes construtivos das paredes de alvenaria participante que influenciam o comportamento do pórtico pré-moldado frente às ações horizontais. No Brasil, a contribuição dessas paredes não é considerada no dimensionamento da estrutura devido à falta de informações e à sua complexidade, o que leva a projetos mais conservadores. Neste estudo, identifica-se os principais detalhes construtivos das paredes de alvenaria participante que influenciam no contraventamento das edificações. Também, são consideradas as variáveis e mecanismos que algumas das principais normas internacionais utilizam na análise de alvenaria participante em pórticos para a estabilidade das estruturas. Além de, realizar a comparação entre esses mecanismos normatizados e o modelo realizado a partir do uso de ferramenta computacional utilizando o Método de Elementos Finitos (MEF). Mesmo existindo unanimidade quanto aos efeitos de enrijecimento no pórtico pela alvenaria participante, percebe-se que a formalização de sua consideração no contraventamento de edifícios de estruturas pré-moldadas requer um maior conhecimento do meio técnico. Este trabalho visa, portanto, contribuir para divulgar e analisar criticamente os detalhes construtivos e os métodos usuais para consideração da alvenaria participante no projeto de edifícios

Improved testing procedures to assess the physical and mechanical properties of ceramic blocks

In Brazil, ceramic blocks have a significant share of the masonry construction market. Thus, an experimental testing program was devised to determine the physical and mechanical properties of ceramic blocks from different regions of Brazil. The experimental program included blocks from five Brazilian states and ten different producers, and the properties studied were absorption, material density, efflorescence, abrasion, compressive strength, and resistance towet-dry cycles. The purpose of determining these material properties is to set guidelines to standardize the performance of same-geometry blocks. The material density test method and the wet- and dry cycle test method are being proposed as new tests and are not usually specified in international codes. The objective of the wet and dry cycle test is to determine a durability parameter for blocks that are not subjected to freeze-thaw cycles. The analysis of the results identified important relationship between these properties.Keywords: masonry, clay, ceramic blocks, test in blocks.

Rapid Saline Permafrost Thaw Below a Shallow Thermokarst Lake in Arctic Alaska

Permafrost warming and degradation is well documented across the Arctic. However, observation- and model-based studies typically consider thaw to occur at 0°C, neglecting the widespread occurrence of saline permafrost in coastal plain regions. In this study, we document rapid saline permafrost thaw below a shallow arctic lake. Over the 15-year period, the lakebed subsided by 0.6 m as ice-rich, saline permafrost thawed. Repeat transient electromagnetic measurements show that near-surface bulk sediment electrical conductivity increased by 198% between 2016 and 2022. Analysis of wintertime Synthetic Aperture Radar satellite imagery indicates a transition from a bedfast to a floating ice lake with brackish water due to saline permafrost thaw. The regime shift likely contributed to the 65% increase in thermokarst lake lateral expansion rates. Our results indicate that thawing saline permafrost may be contributing to an increase in landscape change rates in the Arctic faster than anticipated

Ice-rich permafrost thaw under sub-aquatic conditions

Degradation of sub-aquatic permafrost can release large quantities of methane into the atmosphere, impact offshore drilling activities, and affect coastal erosion. The degradation rate depends on the duration of inundation, warming rate, sediment characteristics, the coupling of the bottom to the atmosphere through bottom-fast ice, and brine injections into the sediment. The relative importance of these controls on the rate of sub-aquatic permafrost degradation, however, remains poorly understood. This poster presents a conceptual evaluation of sub-aquatic permafrost thaw mechanisms and an approach to their representation using one-dimensional modelling of heat and dissolved salt diffusion. We apply this model to permafrost degradation observed below Peatball Lake on the Alaska North Slope and compare modelling results to talik geometry information inferred from transient electromagnetic (TEM) soundings

Predictive Stator Flux and Load Angle Control of Synchronous Reluctance Motor Drives Operating in a Wide Speed Range

This paper presents a new simplified finitecontrol- set model predictive control strategy for synchronous reluctance motors operating in the entire speed range. It is a predictive control scheme that regulates the stator flux and the load angle of the synchronous reluctance motor, incorporating the ability to operate the drive in the field-weakening region and respecting the motor voltage and current limits as well as the load angle limitation needed to operate this type of motor in the maximum torque per voltage region. The proposed control strategy possesses some attractive features, such as no need for controller calibration, no weighting factors in the cost function, good robustness against parameter mismatch, and smaller computational cost compared to more traditional finite-control-set model predictive control algorithms. Simulation and experimental results obtained using a high-efficiency synchronous reluctance motor demonstrate the effectiveness of the proposed control scheme.info:eu-repo/semantics/publishedVersio

Estudo teórico e experimental de paredes esbeltas de alvenaria estrutural

Um dos fatores a serem levados em conta no dimensionamento de elementos comprimidos é sua esbeltez. Até hoje no Brasil utiliza-se o conceito de esbeltez simplificado, no qual o comprimento de flambagem é determinado por uma altura efetiva (hef), e o raio de giração é substituído por um parâmetro chamado espessura efetiva (tef), para o cálculo de fator minorador de resistência. Outras normas de alvenaria estrutural, como as norte-americana, europeia e australiana, trazem também em sua formulação de cálculo da capacidade de carga de uma parede comprimida um fator redutor de resistência. Já a normalização canadense indica que seja feita uma análise mais próxima da realidade, considerando o equilíbrio na configuração deformada da parede (análise P-Delta). Um programa experimental que envolveu 18 ensaios de paredes de blocos cerâmicos e de concreto com elevada esbeltez, obtida com a utilização de blocos de pequena espessura, é aqui relatado. As previsões da capacidade de carga para o caso de blocos de concreto de geometria vazada foram próximas aos resultados dos ensaios. No caso dos blocos cerâmicos utilizados, de geometria complexa, com as paredes dos blocos também vazadas, apenas a aproximação da norma canadense permitiu obter com algum grau de segurança e proximidade os resultados dos ensaios. Paredes mais esbeltas e com blocos de geometrias complexas exigem procedimentos mais refinados para o cálculo, em que o processo P-Delta e a verificação da seção com material não resistente à tração podem ser uma solução

Aderência de revestimentos em paredes de blocos cerâmicos com função estrutural

O presente trabalho tem por objetivo verificar o comportamento mecânico dos revestimentos cerâmicos frente aos carregamentos na alvenaria estrutural. Neste estudo são apresentados os resultados experimentais e conclusões sobre o comportamento de paredes revestidas quando submetidas a carregamentos verticais crescentes até a ruptura. Os revestimentos foram fixados com argamassa colante industrial, aplicados em paredes de blocos cerâmicos com e sem emboço. Ao longo dos ensaios foram registrados todos os eventos considerados importantes, tais como deformações, início de fissuração, descolamento dos revestimentos, formas e cargas de rupturas. Dessa forma, foi possível quantificar a relação dos carregamentos presentes nas paredes com as fissurações e desprendimentos dos revestimentos cerâmicos, onde se pode verificar que os problemas patológicos ocorreram próximos aos limites de carregamento da estrutura, indicando que o sistema de revestimentos não sofreram relativas alterações visuais e mecânicas dentro do regime estrutural de utilização

Remote sensing-based statistical approach for defining drained lake basins in a continuous Permafrost region, North Slope of Alaska

Lake formation and drainage are pervasive phenomena in permafrost regions. Drained lake basins (DLBs) are often the most common landforms in lowland permafrost regions in the Arctic (50% to 75% of the landscape). However, detailed assessments of DLB distribution and abundance are limited. In this study, we present a novel and scalable remote sensing-based approach to identifying DLBs in lowland permafrost regions, using the North Slope of Alaska as a case study. We validated this first North Slope-wide DLB data product against several previously published sub-regional scale datasets and manually classified points. The study area covered \u3e71,000 km2, including a \u3e39,000 km2 area not previously covered in existing DLB datasets. Our approach used Landsat-8 multispectral imagery and ArcticDEM data to derive a pixel-by-pixel statistical assessment of likelihood of DLB occurrence in sub-regions with different permafrost and periglacial landscape conditions, as well as to quantify aerial coverage of DLBs on the North Slope of Alaska. The results were consistent with previously published regional DLB datasets (up to 87% agreement) and showed high agreement with manually classified random points (64.4–95.5% for DLB and 83.2– 95.4% for non-DLB areas). Validation of the remote sensing-based statistical approach on the North Slope of Alaska indicated that it may be possible to extend this methodology to conduct a comprehensive assessment of DLBs in pan-Arctic lowland permafrost regions. Better resolution of the spatial distribution of DLBs in lowland permafrost regions is important for quantitative studies on landscape diversity, wildlife habitat, permafrost, hydrology, geotechnical conditions, and high-lat-itude carbon cycling