A two-dimensional ordinary state-based peridynamic model for surface fatigue crack propagation in railheads

Based on ordinary state-based peridynamic theory, a 2D peridynamic model has been established to investigate fatigue crack propagation in railheads. The proposed model is verified in terms of rail deformation under a quasi-static load and the ductile material-related fatigue failure model. Good agreements have been achieved between a finite...

Effect of ultra-fine fly ash on the mechanical and shrinkage properties of ultra-high performance concrete

This paper reports on a study to determine the possibility of using ultra-fine fly ash (UFA) for partial or total replacement of normal fly ash (NFA) in ultra-high performance concrete (UHPC). Workability, microstructure, porosity, drying shrinkage as well as mechanical properties were comprehensively studied to investigate the influence of UFA...

Deterioration of organic coatings on concrete under artificial aging

The deterioration of organic coatings on concrete is closely linked to the efficiency in the protection process of reinforced structures. In the present work, polyurea resin and epoxy resin, which are widely used engineering coatings, were selected to measure and compare the performance under artificial aging. Fourier Transform infrared...

Effect of fine aggregate on rheological properties of ultra-high performance concrete（UHPC)

In this paper, four kinds of ecological fine aggregates (manufactured sand, recycled sand, aeolian sand and river sand) were used to prepared UHPC, the effects of the fine aggregates on the workability, rheological properties and mechanical properties of UHPC were studied. The results reveal that the type and content of fine aggregate have an...

The role of H₂ in Fe carburization by CO in Fischer-Tropsch catalysts

The formation of Fe-carbide phases is relevant to the synthesis of Fischer-Tropsch synthesis catalysts. We investigated the carburization of Raney Fe as a model catalyst using spectroscopic and temperature-programmed techniques. IR spectroscopy shows that CO dissociation already occurs at −150 °C, while C diffusion into metallic Fe requires...

CO₂ migration and distribution in multiscale-heterogeneous deep saline aquifers

Large volumes of carbon dioxide (CO₂) captured from carbon emission source can be stored in deep saline aquifers as a mean of mitigating climate change. The deep saline aquifers are naturally heterogeneous at multiple scales. It is important to generate representative multiscale heterogeneous fields of various hydrogeologic...

Show and speak: Directly synthesize spoken description of images

This paper proposes a new model, referred to as the show and speak (SAS) model that, for the first time, is able to directly synthesize spoken descriptions of images, bypassing the need for any text or phonemes. The basic structure of SAS is an encoder-decoder architecture that takes an image as input and predicts the spectrogram of speech that...

Experimental and analytical studies on shear behaviors of FRP-concrete composite sections

The design of FRP profile-concrete composite sections, including beams and decks, is usually governed by the shear strength of the FRP profiles. However, analytical methods that can precisely predict the shear capacity of the composite sections have not been well developed, because there is lack of knowledge of the FRP-concrete composite...

Inconsistencies Among Spectral Robustness Metrics

Network robustness plays a critical role in the proper functioning of modern society. It is common practice to use spectral metrics, to quantify the robustness of networks. In this paper we compare eight different spectral metrics that quantify network robustness. Four of the metrics are derived from the adjacency matrix, the others follow...

Laboratory and numerical investigation of microwave heating properties of asphalt mixture

Microwave heating is an encouraging heating technology for the maintenance, recycling, and deicing of asphalt pavement. To investigate the microwave heating properties of asphalt mixture, laboratory tests and numerical simulations were done and compared. Two types of Stone Mastic Asphalt (SMA) mixture samples (with basalt aggregates and steel...

Characterization of bitumen modified with pyrolytic carbon black from scrap tires

Pyrolytic carbon black (CB _p ) from scrap tire pyrolysis is a potential modifier for the bitumen industry. Binders containing different contents of CB _p were prepared and experimentally investigated to examine the effects of CB _p on the electrical and thermal conductivity, conventional physical properties,...

Design and characterization of zero magnetic field chambers for high efficiency neutron polarization transport

Several methods of polarized neutron scattering call for a zero magnetic field (ZF) region to reduce magnetic field integral aberrations while preserving the neutron polarization. Though the design for large angle neutron scattering has been presented in various places, the design characterization and tuning has not been discussed before. In...

Synthesis of stable and low-Co2 selective Ɛ-iron carbide Fischer-Tropsch catalysts

A highly selective and stable ZnO-ZrO₂ solid solution catalyst for CO₂ hydrogenation to methanol

Although methanol synthesis via CO hydrogenation has been industrialized, CO₂ hydrogenation to methanol still confronts great obstacles of low methanol selectivity and poor stability, particularly for supported metal catalysts under industrial conditions. We report a binary metal oxide, ZnO-ZrO₂ solid solution catalyst,...

Investigation of Lagrangian coherent structures in a wake-induced boundary layer transition

The evolution of coherent structures in a flat plate boundary layer transition induced by the cylinder wake is investigated using the particle image velocimetry (PIV) technique. The finite-time Lyapunov exponent (FTLE), which characterizes the amount of stretching about the flow trajectory, is used to extract the Lagrangian coherent structures....