Michigan Technological University

    TeV gamma-ray emission from the Cygnus region with Milagro

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    Analysis of diffuse TeV gamma-ray emission can provide clues about the origin of VHE galactic cosmic rays. Previous studies of the galactic diffuse flux with Milagro show an excess of gamma-rays when compared to cosmic ray propagation models in certain regions of the galactic plane. One of these regions is the Cygnus region, which has four known TeV gamma-ray sources in addition to a significant excess of diffuse gamma-rays. In order to better understand this excess, a new analysis technique was used to reconstruct the TeV spectrum of the gamma-rays from the Cygnus region between 1 TeV and 100 TeV for the first time. This technique is based on the fraction of PMTs in the detector that show a significant signal from air shower particles. In this presentation, the analysis technique as well as the resulting spectra in the Cygnus region will be discussed

    Recent advances and directions in the development of bioresorbable metallic cardiovascular stents: Insights from recent human and in vivo studies

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    Over the past two decades, significant advancements have been made regarding the material formulation, iterative design, and clinical translation of metallic bioresorbable stents. Currently, magnesium-based (Mg) stent devices have remained at the forefront of bioresorbable stent material development and use. Despite substantial advances, the process of developing novel absorbable stents and their clinical translation is time-consuming, expensive, and challenging. These challenges, coupled with the continuous refinement of alternative bioresorbable metallic bulk materials such as iron (Fe) and zinc (Zn), have intensified the search for an ideal absorbable metallic stent material. Here, we discuss the most recent pre-clinical and clinical evidence for the efficacy of bioresorbable metallic stents and material candidates. From this perspective, strategies to improve the clinical performance of bioresorbable metallic stents are considered and critically discussed, spanning material alloy development, surface manipulations, material processing techniques, and preclinical/biological testing considerations. Statement of significance: Recent efforts in using Mg, Fe, and Zn based materials for bioresorbable stents include elemental profile changes as well as surface modifications to improve each of the three classes of materials. Although a variety of alloys for absorbable metallic stents have been developed, the ideal absorbable stent material has not yet been discovered. This review focuses on the state of the art for bioresorbable metallic stent development. It covers the three bulk materials used for degradable stents (Mg, Fe, and Zn), and discusses their advances from a translational perspective. Strategies to improve the clinical performance of bioresorbable metallic stents are considered and critically discussed, spanning material alloy development, surface manipulations, material processing techniques, and preclinical/biological testing considerations

    New effective spectral matching measures for hyperspectral data analysis

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    The successful implementation of Spectral Matching Measures (SMMs) often plays a crucial role in material discrimination and classification using hyperspectral dataset. The commonly exploited SMMs, such as Spectral Angle Mapper (SAM), Spectral Information Divergence (SID), and their hybrid, i.e., SIDSAM show limited discrimination ability while discriminating spectrally similar materials. This study presents three new effective SMMs named Dice Spectral Similarity Coefficient (DSSC), Kumar–Johnson Spectral Similarity Coefficient (KJSSC), and a hybrid of DSSC and KJSSC, i.e., KJDSSC , for accurate discrimination of spectrally similar materials. A wide range of hyperspectral datasets of minerals and vegetation acquired under laboratory and real atmospheric conditions were used to compare and evaluate the performance of newly proposed and existing SMMs using Relative Spectral Discrimination Power (RSDPW) statistics. We also assessed the discrimination ability of the proposed and existing SMMs using spectra of selected minerals and vegetation species with an added component of random noise and linearly synthesized mixed spectra. An in-depth comparison and evaluation of different SMMs demonstrated that the discrimination power of the proposed SMMs is significantly higher than existing SMMs. The proposed SMMs also outperform existing SMMs when discriminating noisy and linearly synthesized mixed counterparts. The KJSSC and DSSC show similar efficacy in discriminating spectra of minerals and vegetation, whereas their hybrid measure, i.e., KJDSSC shows significantly higher spectral discrimination ability. Therefore, the newly proposed hybrid measure, i.e., KJDSSC is recommended over existing SMMs for successful material discrimination and classification using hyperspectral data

    Sensor Fusion Approach for Dynamic Torque Estimation with Low Cost Sensors for Boosted 4-Cylinder Engine

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    As the world searches for ways to reduce humanity\u27s impact on the environment, the automotive industry looks to extend the viable use of the gasoline engine by improving efficiency. One way to improve engine efficiency is through more effective control. Torque-based control is critical in modern cars and trucks for traction control, stability control, advanced driver assistance systems, and autonomous vehicle systems. Closed loop torque-based engine control systems require feedback signal(s); indicated mean effective pressure (IMEP) is a useful signal but is costly to measure directly with in-cylinder pressure sensors. Previous work has been done in torque and IMEP estimation using crankshaft acceleration and ion sensors, but these systems lack accuracy in some operating ranges and the ability to estimate cycle-cycle variation. In this study, we show that a data driven system to estimate IMEP using frequency content of crank acceleration, exhaust pressure, and ion current with optimized data windowing can effectively estimate individual cylinder cycle-cycle variation in IMEP over some engine operating regions. Fourier Transforms are used to extract features from the angle domain sensors that are useful for IMEP estimation. A neural network is used to estimate IMEP from those features. Pattern search and grid search algorithms are used to optimize feature extraction, network structure, and network training hyper-parameters with dual objectives of minimizing error and network complexity. These derivative free optimization techniques drove the IMEP estimation error down to 16 kPa over a transient drive cycle (using production possible sensors) and allow it to estimate cycle-cycle variation in some conditions

    A structural design for semi-rigid base asphalt pavement based on modulus optimization

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    The early damage of the semi-rigid base asphalt pavement is related to the pavement structure modulus\u27s unreasonable matching. In this study, three typical pavement structures were selected to analyze the pavement structures\u27 influence on the pavement service life. A three-dimensional finite element pavement structure model was established. The independent variables are subgrade modulus, base course modulus, and subbase modulus. The deflection, the bottom tensile stress, and maximum shear stress were chosen as the evaluation indexes. The effect of the modulus on the mechanical response of the pavement structure was analyzed. The optimal modulus combination of the pavement structure was determined through multi-factor range analysis. The mechanical response and fatigue life before and after the optimization pavement structure were compared. The results showed that the field measured modulus of Structure 1 and 2 was higher than the design modulus. Moreover, while the modulus of base course and subbase course was increased, the deflection gradually reduced. The base course\u27s bottom tensile stress and the subbase were increased, and the maximum shear stress was basically unchanged. After the modulus combination optimized pavement structure, the mechanical response was significantly reduced. The fatigue life based on the deflection and bottom tensile stress, and the laboratory normalized fatigue equation were significantly increased. By the combination of fatigue performance of pavement materials and pavement structure, it was possible to provide an effective optimization method for the design of semi-rigid base asphalt pavement in this research work

    Towards human-wildlife coexistence through the integration of human and natural systems: The case of grey wolves in the Rocky Mountains, USA

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    Wildlife conservation in the Anthropocene means there is a pressing need to find ways for wildlife and humans to share landscapes. However, this is challenging due to the complex interactions that occur within social-ecological systems (SES). This challenge is exemplified by grey wolf management in the American West, where human governance systems influence where and at what densities carnivores persist, thereby regulating and limiting the impacts of carnivores on both human and ecological communities. Here, we build a SES conceptual framework to disentangle the interdependencies between wolves and humans, including the ecological impacts of wolves and people in anthropogenic landscapes and the socio-economic forces shaping human–wolf interactions now and in the future. A key lesson is that coexistence rests not only on the biophysical capacity of a landscape to be shared by humans and wolves, but also on the capacity for human societies to adjust to and accept some level of conflict with wolves. As such, a holistic view that recognizes humans, our social systems and institutions as key actors and attributes of ecological systems can advance the theory and practice of coexistence

    Session 1B Sustainability, Bangladesh and their connection to human and environmental well being.

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    In this project, we would like to explore the interlinkages of our three SDGs, our indicator species, and the country of Bangladesh to the topic of sustainability. As climate change and human development have created negative environmental impacts worldwide, we are looking towards creating a sustainable and efficient future that benefits both human populations and the health of worldwide ecosystems

    Design of Copper and Silicon Carbide (SiC) Reinforced Recycled Aluminium Matrix Composites Through Sintering + Forging

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    The present work, reviews the mechanical and microstructural analyses, of copper and silicon carbide reinforced recycled aluminium matrix (Alumix 431) composites manufactured by sinter+forging technique. Static compression, impact tests and also scratch damage tests were carried out. Detail analyses of Scanning Electron Microscopy (SEM) supported by XRD, thermal and electrical conductivity measurements have been carried out on the specimens before and after the tests. The results exposed that, the composites have homogeneous structure without porosity and very homogeneous distribution of fine silicon carbide (SiC) particles. The failure damage in composites occurs in both matrix and particles implying good chemical bonding diffusion between matrix and particles. This composite will be applied on the pieces with high thermal conductivity and high surface damage resistant

    Comparative water use of native and invasive plants at multiple scales: A global meta-analysis

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    Ecohydrology and invasive ecology have become increasingly important in the context of global climate change. This study presents the first in-depth analysis of the water use of invasive and native plants of the same growth form at multiple scales: leaf, plant, and ecosystem. We reanalyzed data for several hundred native and invasive species from over 40 published studies worldwide to glean global trends and to highlight how patterns vary depending on both scale and climate. We analyzed all pairwise combinations of co-occurring native and invasive species for higher comparative resolution of the likelihood of an invasive species using more water than a native species and tested for significance using bootstrap methods. At each scale, we found several-fold differences in water use between specific paired invasive and native species. At the leaf scale, we found a strong tendency for invasive species to have greater stomatal conductance than native species. At the plant scale, however, natives and invasives were equally likely to have the higher sap flow rates. Available data were much fewer for the ecosystem scale; nevertheless, we found that invasive-dominated ecosystems were more likely to have higher sap flow rates per unit ground area than native-dominated ecosystems. Ecosystem-scale evapotranspiration, on the other hand, was equally likely to be greater for systems dominated by invasive and native species of the same growth form. The inherent disconnects in the determination of water use when changing scales from leaf to plant to ecosystem reveal hypotheses for future studies and a critical need for more ecosystem-scale water use measurements in invasive- vs. native-dominated systems. The differences in water use of native and invasive species also depended strongly on climate, with the greater water use of invasives enhanced in hotter, wetter climates at the coarser scales. © 2010 by the Ecological Society of America

    Nanomagnetic route to bias-magnet-free, on-chip Faraday rotators

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    The miniaturization of Faraday rotator elements is of interest in optical telecommunications for the production of small isolator components. Here we discuss the fabrication of bias-magnet-free-waveguide Faraday rotators for ultrasmall planar device applications. Photonic-crystal structures on magnetic films can yield a significant enhancement in magneto-optic rotation efficiency and an overall reduction in device dimensions. By introducing single-domain magnetic nanoparticles as defects in the photonic bandgap, we show that one can maintain a high degree of coercivity in the Faraday rotator, thus obviating the need for external magnets. We present a theoretical discussion of the formation of single-domain particles in magnetic garnet films, their reversal field characteristics, and the waveguide properties and magneto-optic response of photonic crystals with single-domain defects. © 2005 Optical Society of America
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