High Efficiency Organic Solar Cells: December 16, 2009 - February 2, 2011

Details on the development of novel organic solar cells incorporating Trimetasphere based acceptors are presented including: baseline performance for Lu-PCBEH acceptor blended with P3HT demonstrated at 4.89% PCE exceeding the 4.5% PCE goal; an increase of over 250mV in Voc was demonstrated for Lu-PCBEH blended with low band gap polymers compared to a comparable C60-PCBM device. The actual Voc was certified at 260mV higher for a low band gap polymer device using the Lu-PCBEH acceptor; and the majority of the effort was focused on development of a device with over 7% PCE. While low current and fill factors suppressed overall device performance for the low band gap polymers tested, significant discoveries were made that point the way for future development of these novel acceptor materials

Adversarial Stacked Auto-Encoders for Fair Representation Learning

Training machine learning models with the only accuracy as a final goal may promote prejudices and discriminatory behaviors embedded in the data. One solution is to learn latent representations that fulfill specific fairness metrics. Different types of learning methods are employed to map data into the fair representational space. The main purpose is to learn a latent representation of data that scores well on a fairness metric while maintaining the usability for the downstream task. In this paper, we propose a new fair representation learning approach that leverages different levels of representation of data to tighten the fairness bounds of the learned representation. Our results show that stacking different auto-encoders and enforcing fairness at different latent spaces result in an improvement of fairness compared to other existing approaches.Comment: ICML2021 ML4data Workshop Pape

On the Fairness of Generative Adversarial Networks (GANs)

Generative adversarial networks (GANs) are one of the greatest advances in AI in recent years. With their ability to directly learn the probability distribution of data, and then sample synthetic realistic data. Many applications have emerged, using GANs to solve classical problems in machine learning, such as data augmentation, class unbalance problems, and fair representation learning. In this paper, we analyze and highlight fairness concerns of GANs model. In this regard, we show empirically that GANs models may inherently prefer certain groups during the training process and therefore they're not able to homogeneously generate data from different groups during the testing phase. Furthermore, we propose solutions to solve this issue by conditioning the GAN model towards samples' group or using ensemble method (boosting) to allow the GAN model to leverage distributed structure of data during the training phase and generate groups at equal rate during the testing phase.Comment: submitted to International Joint Conference on Neural Networks (IJCNN) 202

Building a Practical Natural Laminar Flow Design Capability

A preliminary natural laminar flow (NLF) design method that has been developed and applied to supersonic and transonic wings with moderate-to-high leading-edge sweeps at flight Reynolds numbers is further extended and evaluated in this paper. The modular design approach uses a knowledge-based design module linked with different flow solvers and boundary layer stability analysis methods to provide a multifidelity capability for NLF analysis and design. An assessment of the effects of different options for stability analysis is included using pressures and geometry from an NLF wing designed for the Common Research Model (CRM). Several extensions to the design module are described, including multiple new approaches to design for controlling attachment line contamination and transition. Finally, a modification to the NLF design algorithm that allows independent control of Tollmien-Schlichting (TS) and cross flow (CF) modes is proposed. A preliminary evaluation of the TS-only option applied to the design of an NLF nacelle for the CRM is performed that includes the use of a low-fidelity stability analysis directly in the design module

NEW FLAVONOIDS FROM THE AERIAL PARTS OF POLYGONUM EQUISETIFORME SM (POLYGONACEAE)

Objective: The current study was to deal the isolation and identification of secondary metabolites from Polygonum equisetiforme and evaluation of antioxidant activity of its extract.Methods: The methanol-water extract (7:3) of the air-dried aerial parts of Polygonum equisetiforme was fractionated and separated to obtain the isolated compounds by different chromatographic techniques. Structures of these compounds were elucidated by UV and 1Dâ„2D Hâ„ C NMR spectroscopy and compared with the literature data. The crude extract was evaluated for in vitro antioxidant activity using the 2,2 diphenyl dipicryl hydrazine (DPPH) method.Results: Ten secondary metabolites were isolated from Polygonum equisetiforme in this study. Of which three new flavonoids named as 3,5,7,2',5' pentahydroxyflavone 3-O-b-D-glucopyranoside (1), 3,5,7,2',5' pentahydroxyflavone 3-O-b-D-glucopyranoside 8 C-sulphated (2) and quercetin 3-O-β-D-glucucorinde 6''-methyl ester 8-sulphated (3) as well as quercetin 3-O-β-D-glucucorinde methyl ester (4), quercetin 3-O-β-D-glucopyranoside (5), quercetin 7-O-β-D-glucopyranoside (6), quercetin(7), myricetin (8), P-methoxy gallic acid methyl ester (9) and gallic acid (10). The antioxidant potential of P. equisetiforme extract was evaluated by investigating it's total phenolic and flavonoid content and DPPH radical scavenging activity whereby the extract showed significant antioxidant activity (IC50 = 37.45 μg/ml). The total phenolic and flavonoid content was found to be 130.79±5.502 and 45.8±1.63 μg/ml, respectively.Conclusion: Polygonum equisetiforme is a promising medicinal plant, and our study tends to support the therapeutic value of this plant as an antioxidant drug

Effect of a collector bag for measurement of postpartum blood loss after vaginal delivery: cluster randomised trial in 13 European countries

Objective To evaluate the effectiveness of the systematic use of a transparent plastic collector bag to measure postpartum blood loss after vaginal delivery in reducing the incidence of severe postpartum haemorrhage

Computational Design and Analysis of a Transonic Natural Laminar Flow Wing for a Wind Tunnel Model

A natural laminar flow (NLF) wind tunnel model has been designed and analyzed for a wind tunnel test in the National Transonic Facility (NTF) at the NASA Langley Research Center. The NLF design method is built into the CDISC design module and uses a Navier-Stokes flow solver, a boundary layer profile solver, and stability analysis and transition prediction software. The NLF design method alters the pressure distribution to support laminar flow on the upper surface of wings with high sweep and flight Reynolds numbers. The method addresses transition due to attachment line contamination/transition, Gortler vortices, and crossflow and Tollmien-Schlichting modal instabilities. The design method is applied to the wing of the Common Research Model (CRM) at transonic flight conditions. Computational analysis predicts significant extents of laminar flow on the wing upper surface, which results in drag savings. A 5.2 percent scale semispan model of the CRM NLF wing will be built and tested in the NTF. This test will aim to validate the NLF design method, as well as characterize the laminar flow testing capabilities in the wind tunnel facility

Effects of acid deposition on calcium nutrition and health of Southern Appalachian spruce fir forests

The role of acid deposition in the health of spruce fir forests in the Southern Appalachian Mountains has been investigated by a wide variety of experimental approaches during the past 10 years. These studies have proceeded from initial dendroecological documentation of altered growth patterns of mature trees to increasingly more focused ecophysiological research on the causes and characteristics of changes in system function associated with increased acidic deposition. Field studies across gradients in deposition and soil chemistry have been located on four mountains spanning 85 km of latitude within the Southern Appalachians. The conclusion that calcium nutrition is an important component regulating health of red spruce in the Southern Appalachians and that acid deposition significantly reduces calcium availability in several ways has emerged as a consistent result from multiple lines or research. These have included analysis of trends in wood chemistry, soil solution chemistry, foliar nutrition, gas exchange physiology, root histochemistry, and controlled laboratory and field studies in which acid deposition and/or calcium nutrition has been manipulated and growth and nutritional status of saplings or mature red spruce trees measured. This earlier research has led us to investigate the broader implications and consequences of calcium deficiency for changing resistance of spruce-fir forests to natural stresses. Current research is exploring possible relationships between altered calcium nutrition and shifts in response of Fraser fir to insect attack by the balsam wooly adelgid. In addition, changes in wood ultrastructural properties in relation to altered wood chemistry is being examined to evaluate its possible role in canopy deterioration, under wind and ice stresses typical of high elevation forests

Stabilization of Tollmien-Schlichting Waves by Mode Interaction

Decreasing skin friction in boundary layers attached to aircraft wings can have an impact in both fuel consumption and pollutant production, which are becoming crucial to reduce operation costs and meet environmental regulations, respectively. Skin friction in turbulent boundary layers is about ten times that of laminar boundary layers. Thus, an obvious method to reduce friction drag is to delay transition to turbulence, which is a fairly involved process in real aircraft wings [J98]. Transition sis promoted either by Tollmien—Schlichting (TS) and Klebanov (K) modes [K94], with the former playing an essential role. Various methods (e.g., suction [SG00,ZLB04], wave cancellation [WAA01,LG06]) have been proposed to reduce TS modes in laminar boundary layers. Mode interaction methods have been successfully used in fluid systems to control related instabilities, such as the Rayleigh—Taylor instability [LMV01]. Here, we present some recent results on using these methods to control TS modes in a compressible, 2D boundary layer over a flat plate at zero incidence. A given unstable TS mode can be stabilized by coupling its spatial evolution with that of a second selected stable TS mode, in such a way that the stable mode takes energy from the unstable one and gives a stable coupled evolution of both modes. The coupling device is a wavetrain in the boundary layer, with appropriate wavenumber and frequency, which can be created by an array of oscillators on the wall, and promotes both (i) parametric coupling between the stable and unstable TS modes and (ii) a mean flow that is also stabilizing. Three differences with wave cancelation methods are relevant. Namely, (a) nonlinear terms play an essential role in the process; (b) the unstable TS mode is stabilized (its growth rate is decreased), not just canceled; and (c) stabilization does not depend on the phase of the incoming wave, which implies that active control is not necessary