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Interference of precipitation in litter production in caatinga area submitted to different managements / InterferÃncia da precipitaÃÃo na produÃÃo de serrapilheira em Ãrea de caatinga submetida a diferentes manejosMarcos Amauri Bezerra MendonÃa 30 April 2014 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / The Caatinga is the least studied and protected across all biomes and in recent years has been changing by human action biome. Studying the behavior of variables that allows the maintenance of natural biome is of great value, considering that the deposition of litter in forest environments is the main route of transfer in the flow of nutrients. The objective of this study assess Identify the relationships between rainfall and dry spells that occur in semiarid and litter production in time for the Caatinga biome, due to management applied to vegetation in semi-arid watersheds. The study was conducted in four watersheds located in the municipality of Iguatu, CearÃ, Brazil. We collected monthly (from January 2008 to December 2012) the litter boxes placed in 20 1 m2 arranged in the vicinity of the main watersheds,
travel. The collected material was placed in paper bags and taken to the Laboratory of Soil Science and Plant Tissue IFCE-Iguatu for the separation into fractions: leaves, branches, reproductive structures and miscellaneous; the dry mass of litter was obtained from a forced circulation oven at a temperature of 70 Â C until achieving constant weight, and then weighed in a precision of 0.01 g. RAL in the watershed management was applied thinning removing all trees with diameter greater than 10 cm leaving the plant remains in the area ; The watershed VN ( native vegetation ) had no treatment remained intact ; SBP ( Broca_Queima_Pastagem ) basin was removed all vegetation and subsequently held the burned watershed ENL , there was the cutting of vegetation leaving the remains enleirados in contour in the basin . The year with the highest total rainfall 2011 , had isolated rainfall events during the dry period in a total of 220 mm . These results show that both dry and rainy
outliers are present always in upper ends and lower rainfall years in the high rainfall comprises isolated and disparate events. Regarding veranicos , the highest number of occurrences in the series for these studies was recorded in class 5 to 10 days ( event 246 ) , and if they are present throughout the rainy season. Throughout the study period there is a cyclic behavior of litter production , with maximum yields between the months of June and July and the minimum yield from November to December period. This fact expresses the strong relationship between the deciduous species that make up the savanna and the rainy season . It is observed that the watershed watershed RAL ( RAL ) was higher than 2008
although the total rainfall in 2009 was lower than in 2008 , the year (2009-2010 ) the leaf fraction contributed 80.14 % of total litter . Given the above it is concluded that : The management employees in the area changed the litter production ; the rainfall amount and
duration of the rainy season influenced the litter production and independent production was seasonal nature of management applied. / A Caatinga à o bioma menos estudado e protegido entre todos os biomas brasileiros e nos Ãltimos anos vem sofrendo alteraÃÃes pela aÃÃo antrÃpica. Estudar o comportamento de variÃveis que possibilita a manutenÃÃo natural do bioma à de grande valia, tendo em vista que
A deposiÃÃo da serapilheira em ambientes florestais à a principal via de transferÃncia no fluxo de nutrientes. Objetivou-se nesse estudo avaliar a Identificar as relaÃÃes existentes entre o regime pluviomÃtrico e os veranicos que ocorrem no semiÃrido e a produÃÃo de serapilheira no tempo para o bioma Caatinga, em funÃÃo do manejo aplicado a cobertura vegetal em microbacias do semiÃrido. O estudo foi desenvolvido em quatro microbacias localizadas no municÃpio de Iguatu, CearÃ, Brasil. Coletou-se mensalmente (de janeiro de 2008 a dezembro de 2012) a serapilheira depositada em 20 caixas de 1 m2 dispostas nas proximidades do curso principal das microbacias, . O material coletado foi acondicionado em sacos de papel e levado ao LaboratÃrio de Solos e Tecidos Vegetais do IFCE-Iguatu para a separaÃÃo nas fraÃÃes: folhas, galhos, estruturas reprodutivas e miscelÃnea; a massa seca de serapilheira foi obtida
atravÃs de uma estufa de circulaÃÃo forÃada numa temperatura de 70 ÂC atà que se obtivesse peso constante, sendo em seguida, pesados em balanÃa de precisÃo de 0,01 g. Na microbacia RAL o manejo aplicado foi o raleamento retirando todas as Ãrvores com diÃmetro maior que 10 cm deixando os restos vegetais na Ãrea; Na microbacia VN (vegetaÃÃo nativa) nÃo houve nenhum tratamento permanecendo intacta; Na bacia PAS (Broca_Queima_Pastagem) foi retirada toda a vegetaÃÃo e posteriormente realizada a queimada a microbacia ENL, realizouse o corte da vegetaÃÃo deixando os restos enleirados em curva de nÃvel na bacia. O ano com maior precipitaÃÃo total, 2011, apresentou eventos de precipitaÃÃes isoladas durante o perÃodo seco em um total de 220 mm. Tais resultados mostram que tanto nos secos como chuvosos, os outliers se fazem presentes sempre nos extremos superiores, bem como nos anos de menor precipitaÃÃo, a altura pluviomÃtrica à composta por eventos isolados e discrepantes. Em
relaÃÃo aos veranicos, o maior nÃmero de ocorrÃncia destes para a sÃrie em estudo foi registrado na classe de 5 a 10 dias (246 eventos), e os mesmos se fazem presente ao longo de toda a estaÃÃo chuvosa. Ao longo do perÃodo estudado observa-se um comportamento cÃclico
da produÃÃo de serapilheira, com produtividades mÃximas entre os meses de junho e julho e produtividade mÃnima no perÃodo nov-dez. Tal fato expressa a forte relaÃÃo existente entre as espÃcies caducifÃlias que compÃem a Caatinga e a quadra chuvosa. Observa-se que a microbacia RAL microbacia (RAL) foi superior a de 2008 embora o total precipitado em 2009 tenha sido inferior ao de 2008, no ano (2009-2010) a fraÃÃo folha contribuiu com 80,14% da serapilheira total. Diante do exposto conclui-se que: Os manejos empregados na
Ãrea alteraram a produÃÃo de serapilheira; o total precipitado e a duraÃÃo do perÃodo chuvoso influenciaram na produÃÃo de serapilheira e a produÃÃo apresentou carÃter sazonal independente do manejo aplicado.
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Ciclagem de nutrientes e variações do microclima em plantações de Eucalyptus grandis Hill ex Maiden manejadas através de desbastes progressivos. / Nutrient cycling and variations of microclimate within a eucalyptus grandis hill ex maiden plantation of a progressive thinning management.Luciana Kolm 29 May 2001 (has links)
O presente trabalho aborda a ciclagem de nutrientes e aspectos do microclima em plantações de Eucalyptus grandis de 20 anos, manejadas pelo método CCT, em 3 intensidades de desbaste (T0 = 0%, T1 = 67% e T2 = 83% de desbaste). As áreas de estudo localizam-se na Fazenda Santa Terezinha, propriedade da empresa Eucatex S.A., no município de Bofete SP. O clima da região é do tipo Cwa, segundo a classificação de Köpen, e o solo é classificado como Latossolo Vermelho-Amarelo transição para Areia Quartzosa. Em relação aos aspectos microclimáticos, verificou-se que os tratamentos desbastados (T1 e T2) interceptaram menos luz que os tratamento testemunha (T0). Seus valores de radiação fotossinteticamente ativa e ILR (%) foram, em geral, maiores que os do T0. As temperaturas mensais variaram pouco entre os tratamentos. O T2 apresentou a maior amplitude térmica, e as temperaturas médias foram ligeiramente superiores às dos demais tratamentos. Em todas as profundidades (0-5, 6-30 e 31-60 cm), o T0 manteve os maiores teores de umidade do solo. A deposição de serapilheira (estudada de outubro de 1998 a setembro de 1999) foi estatisticamente semelhante entre os tratamentos, embora os tratamentos com desbaste (T1 e T2) tenham depositado quantias ligeiramente maiores. Os teores de nutrientes e a sua transferência, pela deposição mensal de serapilheira, foram em geral mais altos nos tratamentos com desbaste. As taxas de deposição anual nos tratamentos T0, T1 e T2 foram de 10,2; 10,9; 10,4 t/ha/ano, respectivamente. A biomassa de serapilheira acumulada sobre o solo foi de 18,1 t/ha no T0, 13,4 t/ha no T1 e 14,8 t/ha no T2. Nos tratamentos com desbaste, os teores médios anuais de nutrientes da serapilheira acumulada foram geralmente iguais ou maiores que os do T0; porém, seus estoques foram inferiores aos do T0. A decomposição da serapilheira foi mais rápida nos tratamentos com desbaste, provocando menores acúmulos desta sobre o solo. Os estoques de P, K, Ca e Mg no solo foram superiores nos tratamentos desbastados (principalmente no T1). Devido à sua lenta velocidade de decomposição e imobilização dos nutrientes na camada de serapilheira, o T0 apresentou os menores estoques de nutrientes no solo (exceto para N). A aplicação de desbastes progressivos em povoamentos de eucaliptos, quando manejados em regimes de ciclos mais longos do que usualmente vem sendo aplicados atualmente (5 - 6 anos), podem favorecer a reciclagem dos nutrientes que entram no ecossistema, conservando mais eficientemente seus estoques no sistema (solo + serapilheira) e contribuindo para manter a produtividade do sítio. / This study characterizes nutrient cycling and microclimate conditions within a 20-year-old Eucalyptus grandis plantation with three thinning intensity treatments of Correlated Curve Trend (CCT) management method (T0 = 0%, T1 = 67% and T2 = 83% of thinning intensity). This project was located in Bofete SP, in the Santa Terezinha Farm, of Eucatex S.A. The climate of site is Cwa, according to Köpen classification, and the type soil is a Haplustox with a transition to Quartz Psamment. In respect to microclimate measurements, the thinned treatments (T1 and T2) intercepted less light than the non-thinned treatment (T0). Its photosynthetic radiation and IRL (%) were generally higher then the T0values. Montly temperature fluctuations were minimal among the treatments. T2 presented the highest thermical fluctuation, and their temperatures were higher than the other treatments. At all soil depths (0-5, 6-30 and 31-60 cm), the moisture contents were greater in T0. Litter production (measured from October, 1998 to September, 1999) was similar among the treatments, but there was somewhat more litterfall in thinned treatments (T1 and T2). Annual litterfall in treatments T0, T1 and T2 were 10.22, 10.87 and 10.39 t/ha/year respectively. The concentration of nutrients and their return through litterfall were generally greater in thinned treatments. Biomass of forest floor litter was 18.13 t/ha in T0, 13.43 t/ha in T1 and 14.83 t/ha in T2. Thinned treatments had equal to or higher than annual concentrations of forest floor litter when compared with T0. However, the amount of nutrients was less than T0. Litter decomposition was faster in the thinned treatments, and there was less forest floor litter in thinned treatments. Soil P, K, Ca and Mg contents were higher in thinned treatments, especially in T1. Due to its slow forest floor litter decomposition and its consequent nutrient immobilization, T0 had lower soil nutrient contents, except for N. The use of thinning practices in long rotation can improve nutrient cycling of atmospheric input, conserve the amount of nutrients in the soil-litter system and improve the site productivity.
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Produtividade e qualidade de híbridos de tomate (Solanum lycopersicum L.) dos segmentos Santa Cruz e Italiano em função do raleio de frutos, em ambiente protegido / Yield and qualitative characterization of tomato (Solanum lycopersicum L.) hybrids of Santa Cruz and Italian types in function of fruit thinning under greenhouse environmental conditionsFernando Hoshino Shirahige 21 July 2009 (has links)
Os objetivos do trabalho foram determinar o efeito do raleio de frutos sobre o rendimento e seus componentes e caracterizar qualitativamente os frutos de híbridos de tomate dos segmentos Santa Cruz e Italiano de crescimento indeterminado, cultivados em ambiente protegido, visando ao consumo in natura. Utilizaram-se 12 cultivares de tomate de mesa, sendo seis híbridos experimentais e seis testemunhas comerciais. Usou-se delineamento em blocos completos ao acaso, com parcelas divididas, com 12 tratamentos e três repetições. As parcelas foram representadas pelas cultivares e as subparcelas pelo efeito de raleio, avaliando-se plantas com e sem raleio de frutos. Avaliaram-se a produção total (PT), comercial (PC) e de frutos nãocomercializáveis (PR), massa média do fruto (MM), número de frutos por planta (FP), número de frutos por inflorescência (FI), número de lóculos por fruto (LC), comprimento (CM), largura (LR) e relação entre comprimento e largura do fruto (CM/LR), tamanho da cicatriz peduncular (CP) e espessura da parede do fruto (EP). Para as análises qualitativas dos frutos, foram avaliados o teor de sólidos solúveis (SS), acidez titulável (AT), teor de ácido ascórbico (AA), pH, relação entre SS e AT (SS/AT) e teor de licopeno (LI). Nas condições em que o presente trabalho foi realizado e baseado nos resultados obtidos, conclui-se que o raleio dos frutos proporciona incremento da produção comercial, massa média, comprimento e largura do fruto para os híbridos THX-02 e THX-03, do segmento Santa Cruz, e THX-04, THX-05 e Netuno, do segmento Italiano e não mostrou vantagens para produção e seus componentes para os demais genótipos e características avaliadas. O raleio também não influencia a qualidade organoléptica dos genótipos avaliados, independentemente do segmento varietal. As diferenças entre elas se devem à constituição genotípica per se. Foi ainda concluído que Avalon apresenta maior teor de ácido ascórbico que Netuno e Sahel, e Débora Max, THX-01, THX-02 e THX-04, são semelhantes entre si quanto ao teor de licopeno, mas diferem de Giuliana, Sahel, THX-03, e THX-06. / The objectives of this work were to determine the effect of cluster thinning on yield and its components on tomato hybrids of the Santa Cruz and Italian types of indeterminate growth, and to perform the qualitative characterization of the fruits, aiming at in natura growth. Treatments consisted of 12 indeterminate fresh-market tomato cultivars (six experimental hybrids and six commercial cultivars). A randomized complete block design was used in this trial, with split-plots, and 12 treatments replicated three times. The hybrid cultivars were allocated in the plots and the fruit thinning effect (with and without manual fruit thinning) was observed in the subplots. Total (PT), marketable (PC) and not marketable fruits (PR) yields, average fruit weight (MM), number of fruits per plant (FP), and, number of fruits per inflorescence (FI), number of locules per fruit (LC), fruit length (CM), fruit width (LR), length/width (CM/LR), size of the stem scar (CP), fruit wall thickness (EP) were measured. For quantitative characterization, soluble solids concentration (SS), ascorbic acid content (AA), tritable acidity (AT), pH, SS and AT ratio (SS/AT) and lycopene (LI) contents were measured. Based on the results of the trial carried out can be concluded that: a) the fruit thinning has increased marketable yield, average weight, length and width for the Santa Cruz hybrids THX-02 and THX-03, and THX-04, THX-05 and Netuno classed as Italian type. Furthermore, this practice did not provide benefits for production and its components for the other genotypes and characteristics evaluated, despite of the varietal type, and does not affect the organoleptic quality of the genotype. It was also concluded that regarding ascorbic acid content Avalon outperforms Netuno and Sahel, and Débora Max, THX-01, THX-02 and THX-04 are similar to each other as the content of lycopene, but differ from Giuliana, Sahel, THX-03, and THX-06.
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A High-Performance Parallel Thinning Approach Using a Non-cubic Grid Structure / Chemnitzer Informatik-Berichte ; CSR-06-08Brunner, David, Brunnett, Guido, Strand, Robin 14 September 2006 (has links) (PDF)
In the past years the so-called body-centered cubic grid (bcc) has been examined and proved to be superior over Cartesian lattices for certain applications. Our work deals with parallel thinning on these bcc grids. We introduce conditions which are sufficient for retaining topology and suggest additional conditions to influence the shape of the resulting skeleton. We further developed an algorithm to extract curve skeletons out of 3d objects in parallel which we also present here.
We show in our results that the developed thinning approach on bcc grids is extremely efficient.
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Tillväxtreaktioner efter gallring på försöksytor med olika täthet i Östergötland / Growth reaction after thinning in plots of various density in ÖstergötlandHammarstedt, Kaisa January 2018 (has links)
Since the 1950-ies, the dominating silvicultural system in Sweden has included establishment and management of even-aged stands, including final felling. Alternative systems such as continuous cover forestry are increasingly catching interest due the lower impact on stand structure and biodiversity advantages for shade-tolerant species. However it is unknown especially to southern Sweden how trees in a continuous cover forestry system react to common silvicultural measures such as thinning. Therefore the effect of different levels of thinning on the radial growth of larger trees was measured and compared to the ingrowth and proportion of live crown at a site in Östergötland. Unlike previous findings the radial growth was higher in the treatment that had been slightly thinned than in the one that had been heavily thinned. The ability to react with increased radial growth after thinning was not depending on the thinning regime but on the tree’s reaction to a previous thinning. Only trees that had not reacted to the previous thinning increased in radial growth. The radial growth varied more within a treatment than between treatments, which points at the difficulty to allocate growth to specific trees.
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Picea abies and climate change – does increasing thinning intensity prevent drought stress?Gebhardt, Timo 03 February 2017 (has links)
No description available.
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[en] AN ALGORITHM FOR CURVE RECONSTRUCTION FROM SPARSE POINTS / [pt] UM ALGORITMO PARA RECONSTRUÇÃO DE CURVAS A PARTIR DE PONTOS ESPARSOSCRISTIANE AZEVEDO FERREIRA 23 January 2004 (has links)
[pt] A reconstrução de curvas e superfícies a partir de pontos
esparsos é um problema que tem recebido bastante atenção
ultimamente. A não-estruturação dos pontos (ou seja,
desconhecimento das relações de vizinhança e proximidade) e
a presença de ruído são dois fatores que tornam este
problema complexo. Para resolver este problema, várias
técnicas podem ser utilizadas, como triangulação de
Delaunay, reconstrução de iso-superfícies através de
Marching Cubes e algoritmos baseados em avanço de
fronteira. O algoritmo proposto consiste de quatro etapas
principais: a primeira etapa é a clusterização dos pontos
de amostragem de acordo com sua localização espacial. A
clusterização fornece uma estrutura espacial para os
pontos, e consiste em dividir o espaço em células
retangulares de mesma dimensão, classificando as células em
cheias (caso possuam pontos de amostragem em seu interior)
ou vazias (caso não possuam pontos de amostragem em seu
interior). A estrutura de dados gerada nesta etapa permite
também obter o conjunto dos pontos de amostragem de cada
uma das células. A segunda etapa é o processamento dos
pontos através de projeções MLS. A etapa de pré-
processameno visa reduzir ruído dos pontos de amostragem,
bem como adequar a densidade de pontos ao nível de detalhe
esperado, adicionando ou removendo pontos do conjunto
inicial. A terceira etapa parte do conjunto das células que
possuem pontos de amostragem em seu interior (células
cheias) e faz a esqueletonização deste conjunto de células,
obtendo, assim, uma aproximação digital para a curva a ser
reconstruída. Este esqueleto é encontrado através do
afinamento topológico das células que possuem pontos. A
implementação do algoritmo de afinamento é feita de modo
que o número de pontos em cada célula seja levado em
consideração, removendo primeiro sempre as células com
menor número de pontos. Na quarta etapa, a reconstrução da
curva é finalmente realizada. Para tal, parte-se do
esqueleto obtido na terceira etapa e constrói-se uma curva
linear por partes, onde cada vértice é obtido a partir da
projeção MLS do ponto médio de cada célula do esqueleto. / [en] Curve and surface reconstruction from sparse data has been
recognized as an important problem in computer graphics.
Non structured data points (i.e., a set of points with no
knowledge of connectivity and proximity) together with
the existence of noise make this problem quite difficult.
In order to solve it, several techniques have been
proposed, such as, some of them are based on Delaunay
triangulation, other are based on implicit surface
reconstruction or on the advancing front techniques. Our
algorithm consists basically in four steps. In the first
step, a clustering procedure is performed in order to group
the sample points according to their spatial location. This
procedure obtains an spatial structure for the points by
subdividing uniformly the plane in rectangular cells, and
classifying them into two categories: empty (when the cell
contains no point inside) or not empty (otherwise). At this
stage, a data structure is built in such way that it is
possible to query the set of sample points that belong to a
given rectangular cell. The second step processes the point
through the Moving Least Squares method. Its objective
is not only to reduce the noise on the data, but also to
adapt the number of point to the desired level, by adding
or removing points from the initial set. The third step
builds the skeleton of the set of cells that have sample
point on its interior. Such skeleton is in fact a digital
approximation for the curve that will be reconstructed. It
is obtained by the use of a topological thinning algorithm,
and its implementation is done in such a way that the
number of points in each cell is considered, for example,
the cells with less number of points are not considered for
the thinning. In the last step, the curve is finally
reconstructed To do so, the skeleton obtained in the third
step is used to construct a piecewise-linear approximation
for the curve, where each vertex is obtained from the MLS
projection on the middle point of the skeleton rectangular
cell.
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Improving Seed Spacing Uniformity of Precision Vegetable PlantersSiemens, M.C., Gayler, R.R. January 2016 (has links)
Equidistant, uniform seed placement is important in lettuce production as seeds are densely planted within the row, typically only about 5 cm apart. When seeds are sown too close together, it is time consuming to thin seedlings to the desired plant spacing of 20 to 30 cm by hand and very difficult to do mechanically. The overall goal of the project was to improve lettuce seed placement accuracy and reduce the percentage of seeds spaced closely together. Specific objectives were: 1) to compare vacuum and belt-type planters to determine which style of planter provides better planting performance, 2) to evaluate belt planter seeding performance with different types of furrow openers, and 3) to develop practical modifications for vacuum planters to improve lettuce seed placement accuracy. Three vacuum planter configurations, an unmodified and two reduced seed drop height designs and a belt planter equipped with two types of furrow openers were tested in situ with pelleted lettuce seed at four travel speeds ranging from 1.6 to 4.0 kph. Belt planter performance was significantly better than that of the vacuum planter. Vacuum and belt planters both provided acceptable levels of performance at speeds below 2.4 kph, but at higher speeds, seed placement accuracy declined rapidly. No differences in planter performance were found between the two belt planter configurations tested. The mid-level drop height vacuum planter configuration had significantly better seed placement precision and fewer closely spaced seed spacings as compared to the unmodified vacuum planter. These findings illustrate the significant effect planter type, travel speed, and drop height have on planter performance. They also contradict the common perception that vacuum planters deliver seed more precisely and with fewer closely-spaced seeds as compared to belt planters. Further study is needed to determine the extent to which planter performance affects hand thinning labor costs, automated machine performance, final plant stand uniformity, and crop yield.
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Determining the Timing and Rate of Southeastern Laurentide Ice Sheet Thinning During the Last Deglaciation with 10Be DipsticksHalsted, Christopher T. January 2018 (has links)
Thesis advisor: Jeremy D. Shakun / The deglacial extent chronology of the southeastern Laurentide Ice Sheet as it retreated through the northeastern United States and southern Quebec has been well constrained by multiple lines of evidence. By comparison, few data exist to constrain the thinning history of the southeastern Laurentide, resulting in lingering uncertainty about volume changes and dynamics of this ice mass during the deglacial period. To address the lack of thinning information, my team collected 120 samples for in-situ `10Be exposure dating from various elevations at numerous mountains in New England and southern Quebec. Monte Carlo regression analyses using the analytical uncertainties of exposure ages from each mountain are used to determine the most-likely timing and rate of ice thinning for that location, a technique known as the ‘dipstick approach’. While this larger project is ongoing, I have processed and measured 10Be concentrations of 42 samples for this thesis and present my preliminary results and interpretation here. Exposure ages from Peekamoose Mt. in southern NY suggest ice thinning early in the deglacial period (~19.5 – 17.5 ka), near the onset of the Heinrich Stadial I cold period. Samples from Franconia Notch, NH, and Mt. Mansfield, VT, suggest ice thinning from approximately 15 – 13 ka in northern New England, roughly coincident with the Bølling-Allerød warm period. Exposure ages from each of the northern New England dipsticks are nearly identical within 1σ internal uncertainty, indicating that ice thinning was rapid. Higher elevation (>1200 m a.s.l.) samples from the northern New England mountains appear to contain inherited 10Be from previous periods of exposure, indicating a lack of glacial erosion on these surfaces. My high-elevation samples with inherited 10Be suggest that these summit landscapes were preserved beneath cold-based, non-erosive ice during the last glacial and deglacial periods. 40 samples that have yet to be processed will provide more information on ice thinning around Killington Mt., VT, Mt. Greylock, MA, Mt. Bigelow, ME, and Mt. Jacques-Cartier, Quebec. Ultimately, this information will be used to create probabilistic reconstructions of the lowering southeastern Laurentide ice surface during its retreat. / Thesis (MS) — Boston College, 2018. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.
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Characterization of Flexible Hybrid Electronics Using Stretchable Silver Ink and Ultra-Thin Silicon DieLedgerwood, Joshua A. 01 June 2017 (has links)
Flexible Hybrid Electronics (FHEs) offer many advantages to the future of wearable technology. By combining the dynamic performance of conductive inks, and the functionality of ultra-thinned, traditional IC technology, new FHE devices allow for development of applications previously excluded by relying on a specific type of electronics technology.
The characterization and reliability analysis of stretchable conductive inks paired with ultra-thin silicon die in theµm range was conducted. A silver based ink designed to be stretchable was screen printed on a TPU substrate and cured using box oven, conveyor convection oven, and photonic curing processes. Reliability tests were conducted including a tape test, crease test, wash test, and abrasion test. Optimization of each curing process resulted in all three methods’ ability to achieve the ink sheet resistance specification of <75mΩ/square/25µm. Reliability tests on the printing concluded that, if fully cured, all samples achieve similar reliability performance. Additionally, a series of 10 mm x 10 mm ultra-thin die were characterized using stylus profilometry and optical measurement in order to test the die quality and readiness for assembly. The die had been thinned from an initial thickness down of 600 µm to a target of 50 µm. A direct inverse relationship was shown between die thickness and die warpage, likely due to high levels of internal stress caused by the dicing and thinning process. Finally, an innovate pairing of serpentine copper clad traces on TPU was tested for reliability performance using traditional solder for die attachment.
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