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  • Experimental Study on Permeability Characteristics of Geotubes for Seepage Analysis on Safety Assessment of Dams
  • Abstract Geotubes are heterogeneous structures composed of filling sand and bag material, and its permeability characteristics are different from that of filling sand. The uncertainty of geotubes permeability characteristics results in the failure of seepage analysis of geotube dams, which restricts the safety assessment of the dams. As the basis of the study on the seepage mechanism of the geotubes, the influence of particle grading on permeability coefficient of filling sand and sand covered with geotextiles were explored by the permeability tests of filling sand with different particle grading under the condition of sand covered with or without geotextiles. And the…
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  • Research on Concrete Beam Crack Recognition Algorithm Based on Block Threshold Value Image Processing
  • Abstract To solve the problem that the digital image recognition accuracy of concrete structure cracks is not high under the condition of uneven illumination and complex surface color of concrete structure, this paper has proposed a block segmentation method of maximum entropy threshold based on the digital image data obtained by the ACTIS automatic detection system. The steps in this research are as follows: 1. The crack digital images of concrete specimens with typical features were collected by using the Actis system of KURABO Co., Ltd., of Japan in the concrete beam bending test. 2. The images are segmented into blocks…
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  • A Deep Learning Based Approach for Response Prediction of Beam-like Structures
  • Abstract Beam-like structures are a class of common but important structures in engineering. Over the past few centuries, extensive research has been carried out to obtain the static and dynamic response of beam-like structures. Although building the finite element model to predict the response of these structures has proven to be effective, it is not always suitable in all the application cases because of high computational time or lack of accuracy. This paper proposes a novel approach to predict the deflection response of beam-like structures based on a deep neural network and the governing differential equation of Euler-Bernoulli beam. The Prandtl-Ishlinskii…
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  • Damage Detection for CFRP Based on Planar Electrical Capacitance Tomography
  • Abstract Due to the widespread use of carbon fiber reinforced polymer/plastic (CFRP), the nondestructive structural health monitoring for CFRP is playing an increasingly essential role. As a nonradiative, noninvasive and nondestructive detection technique, planar electrical capacitance tomography (PECT) electrodes array is employed in this paper to reconstruct the damage image according to the calculated dielectric constant changes. The shape and duty ratio of PECT electrodes are optimized according to the relations between sensitivity distribution and the dielectric constant of different anisotropic degrees. The sensitivity matrix of optimized PECT sensor is more uniform as the result shows, because the sensitivity of insensitivity…
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  • Ambient Vibration Testings and Field Investigations of Two Historical Buildings in Europe
  • Abstract In this study, the methodology and results of ambient vibration-based investigations of the historical Tash Mosque in Kosovo and a 3-story historical building in Bulgaria are presented. The investigations include full-scale in situ testing of both structures due to ambient vibrations induced by micro-seismic, wind, traffic, and other human activities. To this aim, Ranger seismometers and Kinemetric products were used. Measurements were performed in both horizontal directions in several points along the structures’ height utilizing a high-speed data acquisition device. All recorded data have been analyzed and processed by the software developed at IZIIS, and then the processed data were…
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  • The Effects of Different Post-Heat Treatments on Rolling Contact Fatigue Behaviors of Direct Laser Cladding Inconel 625 Coatings
  • Abstract In this paper, the microstructures and rolling contact fatigue behaviors of laser cladding Inconel 625 coatings with or without post-heat treatments were analyzed. The results revealed that the fatigue resistance of the laser cladding coating after any post-heat treatment was worse than that of the as-deposited coating. First, through the finite element analysis, the distribution of stress along the thickness direction of the coating was obtained, and it was concluded that the bonding interface between the coating and the matrix had little effect on the fatigue properties of the coating. Then X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy…
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  • A Review on the Utilization of Waste Material for Autoclaved Aerated Concrete Production
  • Abstract Autoclaved aerated concrete (AAC) has become more attractive due to its excellent and environmental-friendly properties in building construction. AAC is relatively lightweight, possesses lower thermal conductivity, higher heat resistance, lower shrinkage, and fasten construction than normal concrete. AAC is a combination of silica sand, cement, gypsum, lime, water, and an expansion agent. To improve its physical and mechanical properties and reduce its production cost, tremendous innovations where waste materials were utilized as partial replacement of AAC materials were done. This paper is intended to present the literature on the utilization of waste materials as a means of a partial replacement…
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  • Improving the Properties of Fast-Growing Chinese Fir by Vacuum Hot Pressing Treatment
  • Abstract Chinese fir was compressed by vacuum hot pressing and conventional hot pressing at different temperatures (180°C, 200°C and 220°C), respectively. The color parameters of the heat-compressed sample were measured, the relative mechanical properties of the material were tested and changes in the chemistry of fir were investigated using Fourier transform infrared spectroscopy (FTIR) and Xray photoelectron spectroscopy (XPS). The results indicated that the color difference between compressed and untreated wood increased gradually with the increase of temperature. Compared with the conventional hot pressing treatment, the color difference (ΔE*) of the Chinese fir treated by vacuum hot pressing decreased by 43.73%,…
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  • Identification of Phenolic Compounds from K. ivorensis by Selected Chromatographic and Spectrometric Techniques
  • Abstract

    A complementary approach using Liquid Chromatographic-Mass Spectrometric analysis was proposed to characterize phenolic compounds from the methanol-water extracts of K. ivorensis A. Chev. Two High Performance Liquid Chromatography (HPLC) complementary methods were used for the determination of phenolic compounds from the bark, sapwood and heartwood of K. ivorensis. Methods employed involved direct analysis after filtration at 0.20 µm, using a RP C18 column and UV-VIS/ESI-FTMS detection. The methods used were different by their elution gradient and allowed analyzing the chemical composition of three parts of African mahogany extracts. In this study, 22 phenolic compounds and derivatives from K. ivorensis were…

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  • Characterization of Extracts from the Bark of the Gabon Hazel Tree (Coula edulis baill) for Antioxidant, Antifungal and Anti-termite Products
  • Abstract

    Chemical composition of the bark extracts of Coula edulis was investigated to find potential antioxidant, anti-termite and antifungal compounds which can find useful applications in the fields of food, nutraceuticals, cosmetics or agrochemical. Phytochemical screening revealed the presence of several groups of active molecules such as alkaloids, polyphenols, flavonoids, saponins and sterols and/or terpenes in the different extracts. Total phenols, condensed tannins and flavonoids contents corroborated phytochemical screening. Gas chromatography-mass spectrometry (GC-MS) analysis revealed compounds in dichloromethane extract different from those obtained with all the other solvents. Hexadecanoic and trans-9-octadecenoic acids, as well as stigmasterol and β-sitosterol have been identified…

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