281 research outputs found

    Strengthening of Rural Bridges using Rapid-Installation FRP Technology: Route 63 Bridge No. H356, Phelps County

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    This report presents the use of externally bonded fiber reinforced polymers (FRP) laminates for the flexural strengthening of a concrete bridge. The bridge selected for this project is a two-span simply supported reinforced concrete slab with no transverse steel reinforcement located in Phelps County, MO. The original construction combined with the presence of very rigid parapets caused the formation of a 1-inch wide longitudinal crack, which resulted in the slab to behave as two separate elements. The structural behavior was verified using a finite element model (FEM) of the bridge. The bridge analysis was performed for maximum loads determined in accordance with AASHTO 4th edition. The strengthening scheme was designed in compliance with the ACI 440.2R-08 design guide for externally bonded FRP materials, to avoid further cracking and such that the transverse flexural capacity be higher than the cracking moment. The FRP strengthening technique was rapidly implemented. After the strengthening, a load test was performed to validate the bridge model and evaluate the structural behavior according to the AASHTO specifications. The bridge deck was retrofitted after the longitudinal crack was injected with epoxy to allow continuity in the cross section

    Unified Finite Horizon H

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    This paper addresses the H∞ fusion filtering problem for networked dynamical systems, where measurements may arrive at fusion center in four different scenes and the fusion center could receive none, one, or multiple measurements in a fusion period. A unified H∞ performance criterion function, which is suitable for different measurement arrival scenes, is designed for the filtering process of networked dynamical systems. Then, the H∞ performance criterion function is described as an indefinite quadratic inequality and solved by a novel noise projection method in Krein space. On this basis, a unified finite horizon H∞ filtering method is proposed for networked dynamical systems. Simulation results are provided to illustrate the correctness and the effectiveness of the theoretical analysis

    Concrete Surface with Nano-Particle Additives for Improved Wearing Resistance to Increase Truck Traffic

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    This study focused on the use of nanotechnology in concrete to improve the wearing resistance of concrete. The nano materials used were polymer cross-linked aerogels, carbon nanotubes, and nano-SiO2, nano-CaCO3, and nano-Al2O3 particles. As an indirect measurement of the concrete wearing resistance, the tensile and compressive properties and the permeability of concrete were evaluated for various mix designs. The optimal amount of nano material additives were determined following the American Society of Testing Methods (ASTM) standard test methodologies. The test results from the materials were compared for their mechanical behaviors. This type of technology may potentially improve the comfort level of passengers, the safety of highway operations, and the efficiency of fuel consumptions. It may also reduce the emission of CO2 associated with the poor condition of roadways

    Lipidomics for Determining Giant Panda Responses in Serum and Feces Following Exposure to Different Amount of Bamboo Shoot Consumption: A First Step towards Lipidomic Atlas of Bamboo, Giant Panda Serum and Feces by Means of GC-MS and UHPLC-HRMS/MS

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    Lipidic metabolites play essential roles in host physiological health and growth performance, serving as the major structural and signaling components of membranes, energy storage molecules, and steroid hormones. Bamboo, as wild giant pandas' exclusive diet, is the main determinant of giant pandas' lipidome, both as a direct source and through microbiota activity. Interestingly, the consumption of bamboo has attracted little attention from a lipidomic perspective. In the current study, we outline the lipidomic atlas of different parts of bamboo. By gas chromatography-mass spectrometry (GC-MS), we have been able to obtain the absolute quantification of 35 fatty acids pertaining to short chain fatty acids (8), medium chain fatty acids (6), long chain fatty acids (17), and very long chain fatty acids (4), while liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS/MS) allowed us to obtain the relative quantification of another 1638 lipids. Among the fatty acids quantified in absolute terms, eight showed significantly distinct concentrations among different bamboo parts. Subsequently, we investigated how the giant panda's serum and fecal lipidome adapt to the most important annual change in their diet, represented by the consumption of high amounts of bamboo shoots, typical of spring, the weight-gaining season. Five fatty acids were significantly altered in feces and two in serum, respectively, due to the different levels of bamboo shoot consumption. Furthermore, significant differences of the main bacteria strains were observed in feces between the two groups at the genus level, pertaining to Streptococcus, Leuconostoc, and Vagococcus. Correlations between giant panda fecal microbiome and lipidome were evaluated by Pearson correlation analysis. These findings suggest that a balanced diet, important for the overall lipidomic function and giant panda health, could be reached even in this remarkable case of a single food-based diet, by administering to the giant panda's combinations of different parts of bamboo, with specific lipidome profiles

    Atomically dispersed quintuple nitrogen and oxygen co-coordinated zirconium on graphene-type substrate for highly efficient oxygen reduction reaction.

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    A cost-effective and long stability catalyst with decent electrochemical activity would play a crucial role in accelerating applications of metal-air batteries. Here, we report quintuple nitrogen and oxygen co-coordinated Zr sites on graphene (Zr-N/O-C) by using a ball-milling, solid-solution-assisted pyrolysis method. The as-prepared Zr-N/O-C catalyst with 2.93 wt % Zr shows a half-wave potential of 0.910 V, an onset potential of 1.000 V in 0.1 M KOH, impressive durability (95.1% remains after 16,000 s), and long-term stability (5 mV loss over 10,000 cycles). Zn-air batteries with the Zr-N/O-C electrode exhibit a maximum power density of 217.9 mW cm−2 and a high cycling life of over 1,000 h, exceeding the counterpart equipped with a Pt/C benchmark. Theoretical simulations demonstrate that nitrogen and oxygen dual-ligand confinement effectively tunes the d-band center and balances key intermediates binding energy of intrinsic quintuple coordination Zr sites
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