•Review of Fiber-reinforced polymer (FRP) composites in infrastructure is presented.•Performance of FRP strengthening systems in extreme conditions is reviewed.•Limitations, challenges, and research ...needs associated with FRPs are discussed.
Fiber-reinforced polymer (FRP) composites continue to provide designers with the ability to deliver innovative and intelligent solutions to overcome the ever-growing aging issues in infrastructure. Since it has been more than 50 years to the introduction of FRP materials to the construction industry, this paper presents a state-of-the-art review on historic and recent developments of FRP in strengthening and rehabilitation of civil engineering applications. This review highlights some of the classic and modern experimental, numerical, and analytical studies associated with the integration of FRPs into buildings, among other structures. The discussion presented herein aims at covering application of FRP systems in reinforced concrete structural members and also highlights the performance of FRPs (including bonding agents) under extreme conditions such as elevated temperature, saline environment, and cycles of freezing and thawing. This paper also presents a collective perspective on number of limitations, challenges and research needs associated with successful, sustainable, and durable implementation of FRPs in civil infrastructure.
The current method of strengthening reinforced concrete (RC) beams in shear is by externally bonding carbon fiber reinforced polymer (CFRP) sheets to the vertical sides of the beam with different ...orientations and spacing using epoxy adhesives to arrest diagonal cracks. However, in certain applications, the sides of the beam might not be accessible for shear strengthening. The aim of this paper is to investigate the effect of externally bonded CFRP sheets on the load-carrying capacity of shear-deficient RC beams when attached to the beam’s soffit. This will examine the contribution of flexural longitudinal reinforcement ratio in enhancing the shear strength of RC beams. Thirteen beams were cast without transverse reinforcement in the shear span and were divided into three groups with different longitudinal steel reinforcement ratios. The tested specimens failed in shear as a result of a diagonal-tension crack. The increase in the concrete shear capacity of strengthened specimens was in the range of 10–70% compared to the control specimens. This concludes that flexural longitudinal reinforcement ratio has a significant effect on the shear strength of RC beams. The shear strength of the tested specimens were also predicted using different codes guidelines and standards.
We address the problem of separating stars from galaxies in future large photometric surveys. We focus our analysis on simulations of the Dark Energy Survey (DES). In the first part of the paper, we ...derive the science requirements on star/galaxy separation, for measurement of the cosmological parameters with the gravitational weak lensing and large-scale structure probes. These requirements are dictated by the need to control both the statistical and systematic errors on the cosmological parameters, and by point spread function calibration. We formulate the requirements in terms of the completeness and purity provided by a given star/galaxy classifier. In order to achieve these requirements at faint magnitudes, we propose a new method for star/galaxy separation in the second part of the paper. We first use principal component analysis to outline the correlations between the objects parameters and extract from it the most relevant information. We then use the reduced set of parameters as input to an Artificial Neural Network. This multiparameter approach improves upon purely morphometric classifiers (such as the classifier implemented in SExtractor), especially at faint magnitudes: it increases the purity by up to 20 per cent for stars and by up to 12 per cent for galaxies, at i-magnitude fainter than 23.
Wave modelling in coastal and inner seas Cavaleri, L.; Abdalla, S.; Benetazzo, A. ...
Progress in oceanography,
October 2018, 2018-10-00, 2018-10, Letnik:
167
Journal Article, Publication
Recenzirano
Odprti dostop
•A summary of the present state of the art in enclosed sea wave modelling.•Many examples of present modelling capability and limitations.•A deep discussion and analysis of wave-current interactions ...and modelling.•A discussion of the present state of the art in wave modelling.•A look and a prospect for the corresponding possible future developments.
In the long term development of the research on wind waves and their modelling, in particular of the inner and coastal seas, the present situation is framed with a short look at the past, a critical analysis of the present capabilities and a foresight of where the field is likely to go. After a short introduction, Chapter 2 deals with the basic processes at work and their modelling aspects. Chapter 3 highlights the interaction with wind and currents. Chapter 4 stresses the need for a more complete, spectral, approach in data assimilation. Chapter 5 summarizes the situation with a discussion on the present status in wave modelling and a look at what we can expect in the future.
We present two wide-field catalogues of photometrically selected emission line galaxies (ELGs) at z ... 0.8 covering about 2800 deg super( 2) over the south galactic cap. The catalogues were obtained ...using a Fisher discriminant technique described in a companion paper. The two catalogues differ by the imaging used to define the Fisher discriminant: the first catalogue includes imaging from the Sloan Digital Sky Survey and the Wide-field Infrared Survey Explorer, the second also includes information from the South Galactic Cap U-band Sky Survey. Containing respectively 560 045 and 615 601 objects, they represent the largest ELG catalogues available today and were designed for the ELG programme of the extended Baryon Oscillation Spectroscopic Survey (eBOSS). We study potential sources of systematic variation in the angular distribution of the selected ELGs due to fluctuations of the observational parameters. We model the influence of the observational parameters using a multivariate regression and implement a weighting scheme which allows effective removal of all of the systematic errors induced by the observational parameters. We show that fluctuations in the imaging zero-points of the photometric bands have minor impact on the angular distribution of objects in our catalogues. We compute the angular clustering of both catalogues and show that our weighting procedure effectively removes spurious clustering on large scales. We fit a model to the small-scale angular clustering, showing that the selections have similar biases of 1.35/D sub( a)(z) and 1.28/D sub( a)(z). Both catalogues are publicly available. (ProQuest: ... denotes formulae/symbols omitted.)
Baryon acoustic oscillations in the early Universe are predicted to leave an as yet undetected signature on the relative clustering of total mass versus luminous matter. A detection of this effect ...would provide an important confirmation of the standard cosmological paradigm and constrain alternatives to dark matter as well as nonstandard fluctuations such as compensated isocurvature perturbations (CIPs). We conduct the first observational search for this effect, by comparing the number-weighted and luminosity-weighted correlation functions, using the SDSS-III BOSS Data Release 10 CMASS sample. When including CIPs in our model, we formally obtain evidence at 3.2σ of the relative clustering signature and a limit that matches the existing upper limits on the amplitude of CIPs. However, various tests suggest that these results are not yet robust, perhaps due to systematic biases in the data. The method developed in this Letter used with more accurate future data such as that from DESI, is likely to confirm or disprove our preliminary evidence.
This paper presents the development of a 3D nonlinear finite element (FE) model to capture and predict the response of shear deficient simply supported reinforced concrete (RC) beams strengthened ...externally with aluminum alloy plates. Five FE models were developed based on experimental tests conducted by the authors in a previous investigation. The experimental program included four RC beams strengthened in shear with externally bonded structural aluminum alloy plates of grade 5083–0 and tested under four-point loading to failure. The use of this material instead of the conventional fiber reinforced polymer (FRP) materials seemed to be very promising in enhancing both the strength and ductility of the strengthened specimens. The beams were designed to fail in shear and then strengthened with aluminum alloy plates with different strip spacing and orientation. The developed FE models have exact geometry, nonlinear material properties and boundary conditions to that of the experimental specimens. The FE models employed material constitutive laws for the concrete in tension and compression, yielding of the aluminum plates and flexural steel reinforcement. The developed FE models also incorporated the interfacial bond behavior at the aluminum concrete interface. The predicted FE results for the load–midspan deflection are compared to the measured experimental data. Close agreement was found between the predicted and measured results at all stages of loading for the tested specimens. For the maximum load and maximum mid-span deflection, it is observed that the Mean Absolute Percent Error (MAPE) of the prediction for the five specimens is 1.19% and 4.31% and the Normalized Mean Square Error (NMSE) is 0.0005 and 0.004, respectively. It could be concluded that the developed FE model could be used in future investigations to predict the performance of shear deficient RC beams externally strengthened with aluminum alloy plates with different configurations and orientations.
The effect of implantation temperature on the migration behaviour of xenon (Xe) implanted into glassy carbon and the effect of annealing on radiation damage retained by ion implantation were ...investigated. Glassy carbon substrates were implanted with 320 keV Xe+ to a fluence of 2 × 1016 cm-2. The implantation process was performed at room temperature (RT) and 100 °C Some of the as-implanted samples were isochronally annealed in vacuum at temperatures ranging from 300 °C to 700 °C in steps of 100 °C for 10 h. The as-implanted and annealed samples were characterized using Rutherford backscattering spectrometry (RBS) and Raman spectroscopy. The RT implanted depth profiles indicated that the migration of Xe towards the surface of glassy carbon was accompanied by a loss of Xe ions. The samples implanted at 100 °C indicated no diffusion or loss of Xe after annealing at 300 °C. However, annealing at temperatures ranging from 400 °C to 700 °C resulted in a slight shift in the Xe profile tail-end towards the bulk of glassy carbon. The diffusion coefficients (D) in the temperature range of 300 °C–700 °C for the RT and 100 °C implanted samples, activation energies (Ea), and pre-exponential factors (Do), were extracted. The values of D ranged from (9.72 ± 0.48) × 10-21 to (1.87 ± 0.09) × 10-20 m2/s with an activation energy of (6.25 ± 0.31) × 10-5 eV for RT implanted samples, and the samples implanted at 100 °C, D ranged from (3.85 ± 0.19) × 10-21 to (6.96 ± 0.34) × 10-20 m2/s with activation energy of (4.10 ± 0.02) × 10-5 eV. The Raman analysis revealed that implantation at the RT amorphised the glassy carbon structure while the samples implanted at 100 °C showed mild damage compared to RT implantation. Annealing of the RT-implanted sample resulted in some recovery of the damaged region as a function of increasing annealing temperature.
•Room temperature implantation damaged the near-surface region of the glassy carbon substrate.•The 100 °C implantation led to some recovery within the damaged region.•Sequential annealing of the RT-implanted and the 100 °C implanted samples show different migration behaviour of implanted xenon ions.•Faster recovery of the damaged region was observed after annealing the RT implanted samples.
The recent discovery that peroxisome proliferator-activated receptor γ (PPARγ) targeted anti-diabetic drugs function by inhibiting Cdk5-mediated phosphorylation of the receptor has provided a new ...viewpoint to evaluate and perhaps develop improved insulin-sensitizing agents. Herein we report the development of a novel thiazolidinedione that retains similar anti-diabetic efficacy as rosiglitazone in mice yet does not elicit weight gain or edema, common side effects associated with full PPARγ activation. Further characterization of this compound shows GQ-16 to be an effective inhibitor of Cdk5-mediated phosphorylation of PPARγ. The structure of GQ-16 bound to PPARγ demonstrates that the compound utilizes a binding mode distinct from other reported PPARγ ligands, although it does share some structural features with other partial agonists, such as MRL-24 and PA-082, that have similarly been reported to dissociate insulin sensitization from weight gain. Hydrogen/deuterium exchange studies reveal that GQ-16 strongly stabilizes the β-sheet region of the receptor, presumably explaining the compound's efficacy in inhibiting Cdk5-mediated phosphorylation of Ser-273. Molecular dynamics simulations suggest that the partial agonist activity of GQ-16 results from the compound's weak ability to stabilize helix 12 in its active conformation. Our results suggest that the emerging model, whereby “ideal” PPARγ-based therapeutics stabilize the β-sheet/Ser-273 region and inhibit Cdk5-mediated phosphorylation while minimally invoking adipogenesis and classical agonism, is indeed a valid framework to develop improved PPARγ modulators that retain antidiabetic actions while minimizing untoward effects.
Background: PPARγ agonists improve insulin sensitivity but also evoke weight gain.
Results: GQ-16 is a PPARγ partial agonist that blocks receptor phosphorylation by Cdk5 and improves insulin sensitivity in diabetic mice in the absence of weight gain.
Conclusion: The unique binding mode of GQ-16 appears to be responsible for the compound's advantageous pharmacological profile.
Significance: Similar compounds could have promise as anti-diabetic therapeutics.
Reinforced concrete (RC) beams are often strengthened through externally bonded (EB) fiber-reinforced polymer (FRP) systems. In such applications, improving the bending capacity of RC beams is of ...main interest and which is achieved via bonding EB-FRP systems to the soffit of beams. Access to soffit of beams can be restricted by existing structural members or limited (in case a RC beam span over neighboring compartments). In those scenarios, RC beams can still potentially be strengthened in flexure through longitudinal bonding of EB-FRP systems to the sides of beam's web. This paper examines critical parameters that influence the effectiveness of side bonded EB-FRP systems through a newly developed finite element (FE) model. This model utilizes state-of-art simulation techniques and is capable to trace the flexural behavior of RC beams externally strengthened with side-boned FRP laminates throughout all loading stages till failure. The model was validated by comparing with experimental data and the predicted and measured results were in good agreement. The validated model was then utilized to study the effect of concrete compressive strength, FRP material type, FRP size, and steel reinforcement ratio on the behavior of strengthened RC beams. Outcomes of this numerical investigation show the effectiveness of side-bonding FRP systems as an alternative to conventional soffit strengthening systems to improve the flexural capacity of RC beams.
PDF
