4,680 research outputs found
Increased efficiencies on CdTe solar cells via luminescence down-shifting with excitation energy transfer between dyes
No full textThe external quantum efficiencies of CdTe solar cells fabricated by the atmospheric pressure metal organic chemical vapour deposition (AP–MOCVD) method have been measured with one and two dye doped luminescence down-shifting (LDS) layers on top. Excitation energy transfer between the dyes is used to extend the absorption ability of the LDS layer to ?=350 nm and increase the external quantum efficiency (EQE) of the cells for wavelengths ?<540 nm. The observed increase in the EQE corresponds to a rise in the short circuit current density of 1.88 mA/cm2 under AM1.5G illumination spectra, which is equivalent to a 10% relative solar cell efficiency increase. A simple model is presented, which accounts for the absorption and photon collection efficiencies of the LDS layer
Pragas da soja (Glycine max) em Itaubal do Piririm, AP.
No full textNos últimos anos o cultivo da soja (Glycine max) tem sido expandido em áreas de cerrado no Estado do Amapá, alcançando aproximadamente 14.000 ha de área cultivada em 2016. Entre os desafios que os produtores de soja enfrentam, está o estabelecimento do Manejo Integrado de Pragas (MIP). Porém, inicialmente é necessário identificar as pragas que ocorrem nas lavouras locais. Assim, o objetivo desse estudo foi identificar as principais pragas da cultura de soja no Município de Itaubal do Piririm, AP. A área amostral foi delimitada às margens da Rodovia AP-70, área característica de cerrado. Foram visitadas cinco propriedades (>200 ha) que cultivam soja há pelo menos cinco anos. Em cada propriedade, plantas foram inspecionadas aleatoriamente à procura de pragas e danos por ela causados. Insetos imaturos e adultos foram coletados e levados ao Laboratório de Proteção de Plantas da Embrapa Amapá, para identificação. Os resultados das inspeções foram enriquecidos com observações já realizadas pela equipe de pesquisadores. A principal praga que ocorre no cultivo da soja na área amostrada é a lagarta-falsa-medideira [Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae), de ocorrência generalizada nas áreas, causando desfolha de até 40% nas plantas mais atacadas. A mosca-branca [Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae)] tem sido uma grande preocupação, devido à sua a alta abundância populacional e à possibilidade de ser vetora de vírus fitopatogênicos. Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) foi motivo de grande preocupação nas safras de 2013 e 2014, sendo pouco frequente nas safras seguintes. O percevejo-marrom [Euschistus heros (Fabricius) (Hemiptera: Pentatomidae)] tem ocorrência frequente, embora danos significativos não terem sido observados. Sugere-se aos produtores a adoção de medidas de manejo integrado em área-ampla, evitando a dispersão dessas pragas para áreas ainda não infestadas
The Treatment of Ties in AP Correlation
No full textThe Kendall tau and AP correlation coefficients are very commonly use to compare two rankings over the same set of items. Even though Kendall tau was originally defined assuming that there are no ties in the rankings, two alternative versions were soon developed to account for ties in two different scenarios: measure the accuracy of an observer with respect to a true and objective ranking, and measure the agreement between two observers in the absence of a true ranking. These two variants prove useful in cases where ties are possible in either ranking, and may indeed result in very different scores. AP correlation was devised to incorporate a top-heaviness component into Kendall tau, penalizing more heavily if differences occur between items at the top of the rankings, making it a very compelling coefficient in Information Retrieval settings. However, the treatment of ties in AP correlation remains an open problem. In this paper we fill this gap, providing closed analytical formulations of AP correlation under the two scenarios of ties contemplated in Kendall tau. In addition,we developed an R package that implements these coefficients.Best Short Paper Accepted author manuscriptMultimedia ComputingWeb Information System
Delamination Analysis of A Class of AP-PLY Composite Laminates
No full textA recently developed fiber placement architecture, AP-PLY, has been shown to give significantly improved damage tolerance characteristics of composite structures. The behavior of delaminations resulting from low speed impact damage is of particular concern. Major attention has been paid to expand current knowledge on the delamination response of simple AP-PLY composite structure and move towards in-depth understanding of the failure mechanisms behind the damage tolerance. This thesis presents the approaches to predict delamination onset and analyze delamination growth, in support of the search of the optimum woven pattern for AP-PLY composite laminates. The recovered interlaminar stress between layers combined with the maximum stress criterion determined the delamination onset of simple AP-PLY composite laminate under out-of-plane loads. 2D finite element models with cohesive elements inserted in the interfaces of woven layers have been built to evaluate the delamination initiation and propagation in the different woven patterns of simple AP-PLY composite beams. The parameters of the woven pattern, such as the woven angle, the number of woven plies, the number of straight filled plies, and the location of the woven patterns in through the thickness direction, were investigated and shown to have a significant effect on delamination creation and growth. An energy method based on beam theory was proposed to analyze the strain energy release rate (SERR) of an existing crack in an AP-PLY beam structure. The developed analytical method was implemented in isotropic materials and the obtained SERR of a crack was validated by reference results and finite element solutions. The general behavior of crack growth on the left or right crack tip was evaluated and basic trends leading to crack propagation on one side of the crack were established. A correction factor was introduced to improve the accuracy of the SERR of a small crack through the numerical calculation. The singularity of crack tip caused by dissimilar materials was investigated and was found that the inclusion of the singularity effect could increase the accuracy for small cracks. It has been shown that the neutral axis needs to be relocated to decouple the bending and membrane behavior of unsymmetrical composite laminates, thus to meet the requirement of minimizing the strain energy of the delaminated beam to calculate the SERR of a delaminated composite beam. The calculated SERR of a crack in a composite beam has been verified by comparing with a finite element model. The woven plies in AP-PLY composite laminate altered the layup and two conventional laminates with different stacking sequences were identified in an AP-PLY composite laminate based on the assumption that the resin areas were ignored. A step by step approach was developed to obtain the SERR of a crack that goes across different materials. The analytical SERR determined when two materials are used in sequence, sets the stage for optimization of AP-PLY composite laminates without taking account of the effect of the resin area. The procedure of optimization of simple AP-PLY pattern was proposed and industry may benefit for many applications. An equivalent stiffness approach was used to model regions containing resin pockets and straight or inclined composite layers. A series of three point bending tests was carried out where the failure process and loading capacity were evaluated. The methodology, procedure of optimization, philosophy outlined in this thesis might also be applied to the more complicated fully woven AP-PLY composite laminates. The work in this thesis contributes to the understanding of the behavior of AP-PLY composite laminates with delaminations
Structure function analysis of blazars AP Librae and 3c279
No full textHighest Honors in AstronomyBlazars AP Librae and 3c279 are analyzed for microvariability using a technique known as structure function analysis. AP Librae was observed in April
of 2005 and 3c279 was observed in April of 2007. The data for AP Librae was
previously reduced by Andrew Collazzi and the author reduced the data for
3c279. Both sets of data were reduced using Robert Knop's data reduction
program.
The author ran structure function analysis on both sets of data. Structure function analysis is a statistical analysis run on data that is suppose to
nd timescales of variability, periodicity, and the noise type of data. Previous analysis of AP Librae confirmed mircrovariability, which also shows up in
the structure function of AP Librae. Blazar 3c279 was much quieter than AP
Librae and showed no microvariability durning any of the nights.College of Arts and ScienceDepartment of Physics and Astronom
AP-based wireless intrusion detection systems
No full textThis thesis was scanned from the print manuscript for digital preservation and is copyright the author.
Researchers can access this thesis by asking their local university, institution or public library to
make a request on their behalf. Monash staff and postgraduate students can use the link in the References field
Danos da broca do tronco (Cratosomus sp.) em gravioleiras (Annona muricata L.) no Amapá.
No full textO objetivo desse trabalho foi relatar danos da broca do tronco da gravioleira em um plantio conduzido em área de cerrado do Amapá
Environmental toxicity, redox signaling and lung inflammation:the role of glutathione
No full textGlutathione (gamma-glutamyl-cysteinyl-glycine, GSH) is the most abundant intracellular antioxidant thiol and is central to redox defense during oxidative stress. GSH metabolism is tightly regulated and has been implicated in redox signaling and also in protection against environmental oxidant-mediated injury. Changes in the ratio of the reduced and disulfide form (GSH/GSSG) can affect signaling pathways that participate in a broad array of physiological responses from cell proliferation, autophagy and apoptosis to gene expression that involve H(2)O(2) as a second messenger. Oxidative stress due to oxidant/antioxidant imbalance and also due to environmental oxidants is an important component during inflammation and respiratory diseases such as chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, acute respiratory distress syndrome, and asthma. It is known to activate multiple stress kinase pathways and redox-sensitive transcription factors such as Nrf2, NF-kappaB and AP-1, which differentially regulate the genes for pro-inflammatory cytokines as well as the protective antioxidant genes. Understanding the regulatory mechanisms for the induction of antioxidants, such as GSH, versus pro-inflammatory mediators at sites of oxidant-directed injuries may allow for the development of novel therapies which will allow pharmacological manipulation of GSH synthesis during inflammation and oxidative injury. This article features the current knowledge about the role of GSH in redox signaling, GSH biosynthesis and particularly the regulation of transcription factor Nrf2 by GSH and downstream signaling during oxidative stress and inflammation in various pulmonary diseases. We also discussed the current therapeutic clinical trials using GSH and other thiol compounds, such as N-acetyl-l-cysteine, fudosteine, carbocysteine, erdosteine in environment-induced airways disease
The Quest for Deeper Learning and Engagement in Advanced High School Courses
No full text· GLEF and a research team from the University of Washington worked with Washington\u27s Bellevue School District to develop and assess the impact of project-based learning on upper-level courses in high school.
· Research suggests that Advanced Placement (AP) courses may focus too much on accelerated content at the expense of deeper conceptual learning.
· The number of students taking AP courses has grown, but along with this the number failing has increased. GLEF and the research team tested project-based learning (PBL) to counteract this trend.
· Results after two years are promising. Students in the PBL-AP courses are performing as well or better than students in traditional AP courses.
· Other education funders are encouraged to use an iterative design process, work with a diverse design team, and bring in partners who can contribute needed expertise and resources
Threes Get Degrees? Evaluating the Performance of AP-3 Students and AP Credit Acceptance Policy at ASU
No full textabstract: The goal of this study is to test the assumption that an AP score of 3 is equivalent to a C and gain an understanding of how AP-3 students are performing academically at ASU and how to interpret a 3 when evaluating ASU AP credit acceptance policy. Of primary interest is comparing the performance of AP-3 students to those non-AP students that got a C or higher in the corresponding course. To accomplish this, a tabular analysis of academic performance by AP score is conducted using aggregate student data from the ASU 2012-2014 cohorts. Among the performances considered are GPA, time to graduation, performance in the corresponding and following course at ASU, and more. Following this, a model is estimated for the impact that a 3 has on a student’s time to graduation when compared to non-AP students that got a C in the corresponding course. (abstract
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