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1
Zhang, Guojian, Guangli Guo, Chengxin Yu, Long Li, Sai Hu, and Xue Wang. "Monitoring Instantaneous Dynamic Displacements of Masonry Walls in Seismic Oscillation Outdoors by Monocular Digital Photography." Mathematical Problems in Engineering 2018 (August 7, 2018): 1–15. http://dx.doi.org/10.1155/2018/4316087.
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Understanding the development of cracks in masonry walls can provide insight into their capability for earthquake resistance. The crack development is characterized by the displacement difference of the adjacent positions on masonry walls. In seismic oscillation, the instantaneous dynamic displacements of multiple positions on masonry walls can warn of crack development and reflect the propagation of the seismic waves. For this reason, we proposed a monocular digital photography technique based on the PST-TBP (photographing scale transformation-time baseline parallax) method to monitor the instantaneous dynamic displacements of a masonry wall in seismic oscillation outdoors. The seismic oscillation was simulated by impacting a suspended steel plate with a hammer and by simulation software ANSYS (analysis system), for comparative analysis. The results show that it is feasible to use a hammer to impact a suspended steel plate to simulate the seismic oscillation as the stress concentration zones of the masonry wall model in ANSYS are consistent with the positions of destruction on the masonry wall, and that the crack development of the masonry wall in the X-direction could be characterized by a sinusoid-like curve, which is consistent with previous studies. The PST-TBP method can improve the measurement accuracy as it corrects the parallax errors caused by the change of intrinsic and extrinsic parameters of a digital camera. South of the test masonry wall, the measurement errors of the PST-TBP method were shown to be 0.83mm and 0.84mm in the X- and Z-directions, respectively, and in the west, the measurement errors in the X- and Z-directions were 0.49mm and 0.44mm, respectively. This study provides a technical basis for monitoring the crack development of the real masonry structures in seismic oscillation outdoors to assess their safety and has significant implications for improving the construction of masonry structures in earthquake-prone areas.
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Fang, Xia, Yang Wang, Yong Li, Jie Wang, and Libin Zhou. "An End-To-End Model for Pipe Crack Three-Dimensional Visualization Based on a Cascade Neural Network." Applied Sciences 10, no. 4 (February 14, 2020): 1290. http://dx.doi.org/10.3390/app10041290.
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With the continuous progress of machine vision technology, crack detection in pipelines has been greatly improved. For crack detection in deep holes, inner tubes, and other environments, it is not only necessary to detect the existence of cracks, but also to collect important information regarding the crack detection direction for further analysis. Because shooting with a frontal field of view causes the real side wall images to produce certain distortions, the detection and calibration of cracks requires a certain amount of professional technology and time. It usually takes a long time to collect the image to eliminate the distortion, and then to identify the crack and mark the direction according to the data line. Therefore, a simple and efficient end-to-end neural network model for crack recognition and three-dimensional visualization are proposed by using a cascade network and simple recognition technology in conjunction with inertial navigation equipment. In addition, we screen the crack data via pixel calibration and eliminate the ambiguous data to make the visualization more accurate. Experiments in pipelines and burrows show that the accuracy, performance, and efficiency of the proposed method reached a high level.
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Wang, Junbo, Weibing Hu, Xinyu Wang, and Yaozhe Liang. "Experimental Investigation of Crack Initiation and Propagation in the Unreinforced Masonry Specimen Subjected to Vertical Settlement." Advances in Materials Science and Engineering 2021 (February 13, 2021): 1–14. http://dx.doi.org/10.1155/2021/6672037.
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To study the cracking process of the wall caused by differential settlement under a uniformly distributed load on the top of the wall, a laboratory model experiment was carried out on large-scale masonry specimens, and the acoustic emission (AE) technique and digital close-range industrial photogrammetry were adopted to monitor the AE signals and displacement characteristics of the masonry specimens during loading in real time. The results show that, in the case of differential settlement with small settlement on both sides and large settlement in the middle, two main cracks appear on the left and right sides of the wall, extending obliquely from bottom to top. During the loading process, damage of the wall is aggravated due to the differential settlement, and both cumulative ringing count and energy count have different periods of steep rise. With the increase in the load and activation of the AE event, the AE event becomes active, and the cumulative ringing count and cumulative energy curve have an obvious turning point, where the slope of the curve is substantially higher than that before the turning point. By using digital close-range industrial photogrammetry, it is observed that the main oblique crack on the left is mainly caused by the difference in the vertical deformation, while the main oblique crack on the right is caused by different displacements and deformation directions of the wall on both sides of the crack.
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Shen, Chao, Chuan Li, Yun Shui Xu, Qing Hua Yan, Shao Quan Zhang, Yan Chen, Xiao Ping Xu, Xiang Chun Xu, and Ying Nan Li. "FBG Displacement Sensor Application Research on Geology Security Monitoring of Substation." Advanced Materials Research 503-504 (April 2012): 1393–96. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.1393.
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The great area crack can cause the landslide of the substation sliding. Dislocation is the significant factor to reflect the crack. Embedded the mast structure of FBG displacement sensor, the relative displacement of retaining wall in YanJin substation can be obtained. Placed 3 FBG displacement sensors on the southeast corner of the substation downstream integrated the real-time monitoring system for the dislocation crack of YanJin substation downstream. In the monitoring results of the 479 days, daily average displacement of 3# sensor located in substation downstream maximized to 1.58mm on January 27th 2011; and daily average displacement of 2# sensor located in substation downstream minimized to -1.94mm on September 18th 2011. The monthly rainfall maximized to 123.5mm, 70.7mm, 75.9mm in July, August, September 2011 and minimized to 26.8mm, 12.9mm, and 23.3mm in January 2011, November, December 2010. Considered local precipitation, cracks closely related to the local precipitation.
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Hallee, Mitchell J., Rebecca K. Napolitano, Wesley F. Reinhart, and Branko Glisic. "Crack Detection in Images of Masonry Using CNNs." Sensors 21, no. 14 (July 20, 2021): 4929. http://dx.doi.org/10.3390/s21144929.
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While there is a significant body of research on crack detection by computer vision methods in concrete and asphalt, less attention has been given to masonry. We train a convolutional neural network (CNN) on images of brick walls built in a laboratory environment and test its ability to detect cracks in images of brick-and-mortar structures both in the laboratory and on real-world images taken from the internet. We also compare the performance of the CNN to a variety of simpler classifiers operating on handcrafted features. We find that the CNN performed better on the domain adaptation from laboratory to real-world images than these simple models. However, we also find that performance is significantly better in performing the reverse domain adaptation task, where the simple classifiers are trained on real-world images and tested on the laboratory images. This work demonstrates the ability to detect cracks in images of masonry using a variety of machine learning methods and provides guidance for improving the reliability of such models when performing domain adaptation for crack detection in masonry.
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Qu, Honglue, Chenxu Wang, Gulan Zhang, Ying Liu, Hao Luo, and Qian Mei. "Seismic damage mechanism of bedrock and overburden layer slope reinforced by sheet pile wall." Journal of Geophysics and Engineering 16, no. 4 (July 15, 2019): 667–79. http://dx.doi.org/10.1093/jge/gxz032.
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Abstract Sheet pile walls, widely used in landslide control projects, have demonstrated excellent seismic performance during the great Wenchuan earthquake, as indicated by an investigation of retaining walls following earthquake damage. To further understand the mechanism of seismic damage based on the Hilbert–Huang transform method and marginal spectrum identification theory, a large-scale shaking table test of bedrock and overburden layer slope reinforced by sheet pile wall was carried out, and the mechanism of seismic damage was analysed. The results show that the change in marginal spectrum amplitude and characteristic frequency can clearly indicate the degree of seismic damage to the slope soil. First, the dynamic response of the slope soil near sheet pile wall is smaller than the response observed in soil farther from the wall, and the degree of seismic damage near the wall is relatively weaker than that farther away from the wall. Second, the energy of the seismic wave cannot be completely transferred behind the wall, and the strip cracks of soil behind the wall can be determined. Finally, the slope soil slides along a slip surface so that the front edge of the slope is squeezed due to the vertical tensile cracks at the rear edge. In addition, the results confirm the feasibility of the Hilbert–Huang transform method for studying the mechanism of the seismic damage to the structure-soil coupling system.
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Zhao, Shun Bo, Fu Lai Qu, Shi Min Zhang, Chang Ming Li, and Peng Bing Hou. "Study on Flexural Resistance of Corroded Reinforced Concrete Walls." Advanced Materials Research 742 (August 2013): 76–79. http://dx.doi.org/10.4028/www.scientific.net/amr.742.76.
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On the requirement of evaluating the bearing capacity of corroded reinforced concrete lock-walls servicing on the Yellow River, the experimental study was conducted to investigate the loading behaviours of normal section of lock-walls, which considered the changes of concrete strength and corrosion level of rebar. The rebar corrosion was accelerated by the mixing of sodium chloride (NaCl) into concrete and the electrolyte corrosion technique in condition of dry-wet curing. The vertical eccentric load was applied on the top of the wall. The results show that some horizontal cracks firstly appeared on the surface of walls during the corrosion period and became wider under the vertical load on the wall. The typical ultimate state was flexural failure. The effects of concrete strength and rebar corrosion level on the resistance of normal section are analyzed based on the test data.
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Chen, Yao, Qian Zhang, Jian Feng, and Zhe Zhang. "Experimental Study on Shear Resistance of Precast RC Shear Walls with Novel Bundled Connections." Journal of Earthquake and Tsunami 13, no. 03n04 (June 2019): 1940002. http://dx.doi.org/10.1142/s1793431119400025.
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This study presents shear resistance of precast reinforced concrete (RC) shear walls. A novel assembling method for upper and lower wall panels is proposed, whereas vertical steel bars are grouped into bundles and effectively connected in preformed holes. To evaluate the feasibility and shear resistance of such a connection method, three specimens of precast shear walls with different horizontal steel bars have been constructed and tested under monotonic loading while subjected to a constant vertical compression. The results show that cracks mainly appear under the line that connects the midpoint of tension side and the corner of the compression side. The weak section of these shear walls is at the top of the preformed holes, and through cracks do not appear at the bottom of walls. These innovative precast shear walls are reliable, and no rebar is pulled out or seriously slipped. The yield load of the shear wall is great, and the stage between yield and failure is satisfactory. The bearing capacity declines slowly after the peak value.
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Zejak, Danijela, Nikolay Vatin, and Vera Murgul. "Analysis of the Masonry Structure Calculation with Vertical Ring Beams According to European Standards." Applied Mechanics and Materials 725-726 (January 2015): 111–17. http://dx.doi.org/10.4028/www.scientific.net/amm.725-726.111.
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Analysis of masonry constructions is done simultaneously by applying the Rules on technical standards for masonry walls (PZZ'81), Regulation on technical standards for the constructions in seismic areas (PIOVS'91) and Eurocodes (EC 6 and EC 8). Eurocode presupposes shear force to be a reliable mechanism form calculating shear wall resistance force, which conflicts to the real behavior of constructions during earthquakes. It is therefore recommended determining the seismic masonry resistance according to the current rules that require verification tensile strain, whose possible exceeding leads to the appearance diagonal wall cracks.
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MATSUI, Akio, Hitoshi KIMURA, Yuki IDOSAKO, Masanori TANI, and Minehiro NISHIYAMA. "CRACK OBSERVATION ON REAL BUILDING REINFORCED CONCRETE WALL WITH DEFORMED BARS AT CRACK CONTROL JOINTS AS CRACK INDUCERS." AIJ Journal of Technology and Design 23, no. 55 (2017): 767–72. http://dx.doi.org/10.3130/aijt.23.767.
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Theodossopoulos, Dimitris, James Sanderson, and Michael Scott. "Strengthening Masonry Cross Vaults Damaged by Geometric Instability." Key Engineering Materials 624 (September 2014): 635–43. http://dx.doi.org/10.4028/www.scientific.net/kem.624.635.
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Cross vaults can be easily destabilised when their thrusts are not sufficiently contained by the stiffness of their lateral walls or systems of buttresses. A quarter-scale model from the aisles of Holyrood Abbey church in Edinburgh, which collapsed in 1768 due to excessive load from diaphragm walls that substituted the original roof trusses, demonstrated earlier the pattern of cracks that leads to failure under horizontal spread of supports. A recent model of this vault aimed to study the effects of applying Aramid fibre reinforcement against such failure exactly at the critical cracks, compared to other tests that studied arches or vaults under point load, reinforced continuously. The paper presents how the quality of certain areas of the fabric diverted failure from the longitudinal vertex merging with the detachment of the ribs, as originally observed. Moreover, the repair allowed the vault to resist 50% more spread of its supports, and failure occurred ultimately when new cracks formed in parallel to the repaired ones. The tests and repairs validate qualitative observations on crack patterns and failure of real cases and highlight the benefits and limitations when specific repairs are made instead of wholesome application of a reinforcing mesh at the extrados of vaults.
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Kuklik, Pavel, Martin Valek, Ivana Bozulic, Pratik Gajjar, Chandrashekhar Mahato, and Jacopo Scacco. "Church enclosure walls bearing capacity estimations and its validation on 3D models." MATEC Web of Conferences 310 (2020): 00023. http://dx.doi.org/10.1051/matecconf/202031000023.
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The paper deals with the nonlinear computational modeling of the baroque enclosure masonry walls. The main tasks are input parameters for efficient advanced numerical tools and techniques, which are based on nonlinear and quasi brittle constitutive FEM modeling. For the work was used the knowledge and results from the Broumov Group Churches survey acquired in the frame of international SAHC university cooperation. The goal of the contribution are real bearing capacity parameters of the composite enclosure walls, which leads from standard homogenization techniques. With regards to the material micro modeling of different wall configuration in longitudinal and transversal direction was done with ATENA 2D software to evaluate the safe bearing capacity of the walls. The set of models aim to assess the bearing capacity of the enclosure wall, which is the main structural element in the church. In detail, we will present results from the numerical investigation, and partial in situ testing, from Vižňov, Ruprechtice and Otovice. Finally, we will present calculation of cracks propagation on full 3D church models. Concerning historical structures, it is one way how to validate the quality of estimations and validate numerical models.
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Zouhar, Michal, Pavel Hutař, Martin Ševčík, and Luboš Náhlík. "Pressure Pipe Damage: Numerical Estimation of Point Load Effect." Key Engineering Materials 525-526 (November 2012): 177–80. http://dx.doi.org/10.4028/www.scientific.net/kem.525-526.177.
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The most relevant loading conditions for real polymer pipe systems are not only internal pressure, but also loading caused by sand embedding including bending or different kinds of point loads. It has been shown that service lifetime of buried pipes can be reduced especially due to stress concentration caused by external point loads. If the pipe is loaded locally the stress is concentrated here and a crack can initiate at this position or the existing crack can be affected by corresponding stress redistribution. In the paper the effect of the hard indenter, Poissons ratio, hoop stress level and pipe wall thickness on the crack shape was estimated using numerical simulations of the creep crack propagation based on finite element method. Relation between crack length and crack width was found and expressed by simple relationship. A deeper understanding of the point load effect in order to prevent unexpected failure of the pipelines is of paramount importance for pipeline design.
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Jiang, Shang, and Jian Zhang. "Real‐time crack assessment using deep neural networks with wall‐climbing unmanned aerial system." Computer-Aided Civil and Infrastructure Engineering 35, no. 6 (December 8, 2019): 549–64. http://dx.doi.org/10.1111/mice.12519.
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Morris, Gareth J., Desmond K. Bull, and Brendon A. Bradley. "In situ conditions affecting the ductility capacity of lightly reinforced concrete wall structures in the Canterbury earthquake sequence." Bulletin of the New Zealand Society for Earthquake Engineering 48, no. 3 (September 30, 2015): 190–203. http://dx.doi.org/10.5459/bnzsee.48.3.190-203.
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Following the 2010-2011 Canterbury (New Zealand) earthquake sequence, lightly reinforced wall structures in the Christchurch central business district were observed to form undesirable crack patterns in the plastic hinge region, while yield penetration either side of cracks and into development zones was less than predicted using empirical expressions. To some extent this structural behaviour was unexpected and has therefore demonstrated that there may be less confidence in the seismic performance of conventionally designed reinforced concrete (RC) structures than previously anticipated. This paper provides an observation-based comparison between the behaviour of RC structural components in laboratory testing and the unexpected structural behaviour of some case study buildings in Christchurch that formed concentrated inelastic deformations. The unexpected behaviour and poor overall seismic performance of ‘real’ buildings (compared to the behaviour of laboratory test specimens) was due to the localization of peak inelastic strains, which in some cases has arguably led to: (i) significantly less ductility capacity; (ii) less hysteretic energy dissipation; and (iii) the fracture of the longitudinal reinforcement. These observations have raised concerns about whether lightly reinforced wall structures can satisfy the performance objective of “Life Safety” at the Ultimate Limit State. The significance of these issues and potential consequences has prompted a review of potential problems with the testing conditions and procedures that are commonly used in seismic experimentations on RC structures. This paper attempts to revisit the principles of RC mechanics, in particular, the influence of loading history, concrete tensile strength, and the quantity of longitudinal reinforcement on the performance of real RC structures. Consideration of these issues in future research on the seismic performance of RC might improve the current confidence levels in newly designed conventional RC structures.
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Xu, Xiu Feng, and Tao Wang. "Numerical Study on Precast RC Wall Panels with Angle Steel Boundary Components." Applied Mechanics and Materials 351-352 (August 2013): 578–82. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.578.
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To evaluate the seismic behavior of precast reinforced concrete (RC) shear wall with steel boundary components, two pieces of prefabricated RC wall panels are tested quasi-statically under different axial compression forces. Both panels performed larger ductility than requested by the current seismic design code. Finite element model is then constructed to investigate the function of steel boundary components. The model is first calibrated by the experimental results. The strength, stiffness, and crack development all agree well with the phenomenon observed from experiments. Then the area of steel angle is changed as the main parameter to affect the seismic performance of RC wall panels. It is observed that the strength and ductility of a panel with steel boundary components are larger than that with common rebar boundary elements.
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Yao, Ting, Jian Ye Zhang, Jia Ping Liu, and Qian Tian. "Non-Structural Cracking Analysis of early Age of Reinforcement Concrete Wall." Advanced Materials Research 446-449 (January 2012): 251–59. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.251.
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Structure monitoring has been increasingly valuable in recent years and has taken a leading role in the field of structural engineering. Date collected by early age monitoring represent a unique source of information for understanding the real behavior. In this paper, the temperatures evolution and concrete deformation evolution are obtained by real-time continuous monitoring of Reinforcement concrete(RC) wall. The result shows that the early age thermal cracking is one of the most important origin of several phenomena that imperil durability and shorten the lifespan of the structure. Though the wall is not considered as mass concrete, and has a big radiating surface, the maximum temperature can even reach up to 52°C due to heat generation of cement and the insulation of formwork, which can lead to shrinkage deformation when the temperature decreases. The measured experimental date can provide useful reference for early crack control and durability of RC concrete structure, and they can also be use to verify and improve the accuracy of the numerical results for RC wall, which is available in the future for basis to similar projects and research.
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Winkler, Andreas, Max Ossenbrink, and Moritz Knoche. "Malic Acid Promotes Cracking of Sweet Cherry Fruit." Journal of the American Society for Horticultural Science 140, no. 3 (May 2015): 280–87. http://dx.doi.org/10.21273/jashs.140.3.280.
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When mature sweet cherries (Prunus avium L.) came into contact with sweet cherry juice, cracking dramatically increased. The objectives of our study were: 1) to quantify the cracking of fruit in cherry juice, 2) to determine which constituent(s) of the juice especially promote cracking and, 3) to establish its/their mode of action in promoting cracking. Artificial juice was made up as an aqueous solution of the same five pure chemicals and at the same relative concentrations as the five major osmolytes of real sweet cherry juice. Artificial and real juice was used at half-isotonic concentrations as the real juice from that batch of fruit. Cracking of sweet cherries placed in either artificial or real juice was more rapid and occurred for lower net water uptakes than of fruit placed in half-isotonic polyethylene glycol 6000. The crack-promoting component in sweet cherry juice was malic acid. Further tests with malic acid, and other organic acids, and with different concentrations of malic acid, with and without pH control, and with the enantiomers of malic acid, showed the effects were primarily related to the pH of the incubation solution. Leakage of anthocyanin from discs of flesh was increased in the presence of malic acid and greater in hypotonic than hypertonic solutions, suggesting that malic acid increases the permeability of the plasma membrane and tonoplast and weakens the cell walls. Malic acid may be an important link (amplifier) in a reaction chain that begins with the bursting of individual epidermal cells and ends with the formation of macroscopic skin cracks.
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Rack, A., M. Scheel, L. Hardy, C. Curfs, A. Bonnin, and H. Reichert. "Exploiting coherence for real-time studies by single-bunch imaging." Journal of Synchrotron Radiation 21, no. 4 (May 9, 2014): 815–18. http://dx.doi.org/10.1107/s1600577514005852.
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First real-time studies of ultra-fast processes by single-bunch imaging at the European Synchrotron Radiation Facility are reported. By operating the storage ring of the ESRF in single-bunch mode with its correspondingly increased electron bunch charge density per singlet, the polychromatic photon flux density at insertion-device beamlines is sufficient to capture hard X-ray images exploiting the light from a single bunch (the corresponding bunch length is 140 ps FWHM). Hard X-ray imaging with absorption contrast as well as phase contrast in combination with large propagation distances is demonstrated using spatial samplings of 11 µm and 35 µm pixel size. The images acquired allow one to track crack propagation in a bursting piece of glass, breaking of an electrical fuse as well as cell wall rupture in an aqueous foam. Future developments and their potential in the frame of the proposed Phase II of the ESRF Upgrade Program are discussed.
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Siggins, A. F., and A. N. Stokes. "Circumferential propagation of elastic waves on boreholes and cylindrical cavities." GEOPHYSICS 52, no. 4 (April 1987): 514–29. http://dx.doi.org/10.1190/1.1442321.
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Elastic waves propagating circumferentially on boreholes in rock are potentially useful in many nondestructive testing applications, including measurement of stress‐induced anisotropy and remote detection of cracks on borehole walls. Although analyses of the far‐field response of the surrounding rock to forces applied within boreholes have been described by several authors, little attention has been focused on the response of the borehole wall to such forces. Fourier‐Bessel and finite‐element methods of analysis are used to derive dynamic compliance transfer functions for a borehole in an elastic rock subject to a localized internal force. The analyses are in overall agreement, and both predict that the borehole behaves as a lossy resonant system when excited by such steady‐state forces. The lossy resonances can be attributed to standing surface waves. For a borehole within a rock with Poisson’s ratio of 0.10, the first three dimensionless wavenumbers [Formula: see text] at which resonant amplifications occur are 0.288, 0.836, and 1.403. These wavenumbers are approximately equal to the real part of the first three Rayleigh eigenvalues of the frequency equation for cylindrical cavities in elastic media.
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Demchyna, Bohdan, and Leonid Vozniuk. "Emergency condition of loggies in buildings with supporting brick walls." Theory and Building Practice 2020, no. 2 (November 20, 2020): 28–34. http://dx.doi.org/10.23939/jtbp2020.02.028.
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This article is devoted to the problems of the existing residential buildings of 70-80 years of construction of the last century, which have been in operation for about 50 years and are subject to immediate technical inspection. The most important factor for the safe operation of such buildings is the quality of construction, as in this period the construction was performed with many shortcomings that are manifested today. The article describes the problem of joints of loggias with the building in the design and construction of multi-storey buildings with load-bearing brick walls. Poor ligation of bricks in the masonry, as well as the lack of quality ligation of the transverse walls of loggias with load-bearing longitudinal walls of the building leads to the formation of cracks on the entire height of the loggias, which completely cut them at the abutment, which creates an emergency collapse of building structures. A real example of such a problem in the existing 9-storey building with brick load-bearing walls, where the shortcomings of construction were manifested, namely the poor quality of masonry at the junction of loggias to the load-bearing walls of the building. The structural scheme is also described, as well as the main structures of the building. The main damages and defects are shown. Using the PC "LIRA-SAPR" created a calculation model and compared the results of calculations with the existing condition of the considered area of the building. Recommendations for strengthening the emergency section of the building are given.
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Stepova, Olena, Iryna Parashchiienko, and Iryna Lartseva. "Calculation of Steel Pipeline Corrosion Depth at the Galvanic Corrosive Element Operation." International Journal of Engineering & Technology 7, no. 3.2 (June 20, 2018): 431. http://dx.doi.org/10.14419/ijet.v7i3.2.14566.
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The work is devoted to the issue of calculating the safe life of steel pipelines, which is in accordance with the definition of the residual thickness of the pipe wall.The purpose of this work is to develop a dependence, permitting to calculate the corrosion depth of the steel pipeline in the crack of the insulation coating under the action of an electrolytic medium aggressive to the pipeline metal. To achieve this goal, the following tasks were solved: to develop a dependence based on the mathematical model of a local corrosion element, that would allow to calculate the steel pipeline corrosion depth in the crack of the insulating coating, which would be based on real parameters obtained during the structures examination; to conduct an experimental verification of the steel pipeline’s corrosion damage depth during the galvanic corrosion element’s operation.Based on the mathematical model of the pipeline’s electrochemical corrosion in the crack of the insulating coating under the action of an the electrolytic medium aggressive to the pipeline metal, a dependence was obtained permitting to calculate the depth of the pipeline’s wall corrosion during the work of the macro-galvanic corrosion couples and the stable presence of an aggressive solution in the damaged zone. The experimental studies have proved that direct corrosion tests are consistent with the design values of the macro-galvanic couple’s current. The advantage of this model is the ability to predict the development of corrosion in time, regardless of the aggressive electrolyte’s chemical composition, the possibility of obtaining the required calculation parameters using the structures operated.
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Ko, Bong-Kuk, Woo-Jung Lee, and Jae-Hoon Lee. "A Survey Study on the Defects Found in Low-Income Housing: Case Study Seongnam City Korea." Open House International 42, no. 1 (March 1, 2017): 111–17. http://dx.doi.org/10.1108/ohi-01-2017-b0016.
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The purpose of this study is to understand what health and safety hazards low-income households are subject to by surveying the real conditions of the defective housing of low-income households, and to find improvement strategies. For this purpose, we visited the concentrated areas of the multi-dwelling unit (MDU) (also known as multi-family residential) housing in Jungwon-gu and Sujeong-gu in Seongnam City, Kyunggi-do, one of the representative areas in Korea with a massive distribution of the low-income class. Based on the survey data, the level of housing defects were comparison analyzed per income decile (decile 1, decile 2, deciles 3–4), and per housing location, in the categories of subsidence, cracks in the wall, delamination, water leakage/infiltration, condensation, and contamination. The housing condition per income class was more defective in the decile 2 households rather than in the decile 2 households, and in the substructure more than in the superstructure. Among the six defects, contamination problems, caused by sub-standard living conditions, were the most frequent cases. Structural defects, subsidence and cracks in the wall, were found in the main living areas—the bedrooms and the living rooms. It was confirmed in this study that the conditions of low-income housing are serious, and that it is necessary to explore specific countermeasures in the near future.
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Araneo, Dino, Paolo Ferrara, Fabio Moretti, Andrea Rossi, Andrea Latini, Francesco D'Auria, and Oscar A. Mazzantini. "Integrated Software Environment for Pressurized Thermal Shock Analysis." Science and Technology of Nuclear Installations 2011 (2011): 1–7. http://dx.doi.org/10.1155/2011/840734.
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The present paper describes the main features and an application to a real Nuclear Power Plant (NPP) of an Integrated Software Environment (in the following referred to as “platform”) developed at University of Pisa (UNIPI) to perform Pressurized Thermal Shock (PTS) analysis. The platform is written in Java for the portability and it implements all the steps foreseen in the methodology developed at UNIPI for the deterministic analysis of PTS scenarios. The methodology starts with the thermal hydraulic analysis of the NPP with a system code (such as Relap5-3D and Cathare2), during a selected transient scenario. The results so obtained are then processed to provide boundary conditions for the next step, that is, a CFD calculation. Once the system pressure and the RPV wall temperature are known, the stresses inside the RPV wall can be calculated by mean a Finite Element (FE) code. The last step of the methodology is the Fracture Mechanics (FM) analysis, using weight functions, aimed at evaluating the stress intensity factor (KI) at crack tip to be compared with the critical stress intensity factor KIc. The platform automates all these steps foreseen in the methodology once the user specifies a number of boundary conditions at the beginning of the simulation.
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Kashevarova, Galina, Alexandra Zobacheva, and Ivan Leschev. "Experimental and Numerical Modeling of the Destroying of Brick Masonry for the Analysis of Buildings Accident." Advanced Materials Research 250-253 (May 2011): 3670–73. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.3670.
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The results of experiments and numerical modeling of fracturing of samples of brick masonry are presented; complete stress-strain diagram for samples are obtained; a possibility of replacing a composite material by homogeneous material with effective stiffness characteristics is investigated; the new method and computer simulation for these purposes are suggested. The examples based on real constructions with partial destruction in the form of cracks in load-bearing brick walls have been studied by the means of numerical simulations.
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Bacharz, Kamil, Wioletta Raczkiewicz, Magdalena Bacharz, and Wioletta Grzmil. "Manufacturing Errors of Concrete Cover as a Reason of Reinforcement Corrosion in a Precast Element—Case Study." Coatings 9, no. 11 (October 27, 2019): 702. http://dx.doi.org/10.3390/coatings9110702.
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The article concerns the assessment of technical condition of the precast loggia wall in a large panel building after 25 years of use as well as the cause of its damage. As a result of the study, cracks and losses of the concrete cover were found. Corrosion products were visible on exposed reinforcing rods. The reinforcement distribution and concrete cover thickness in loggia wall were estimated using a rebar detector. The corrosion assessment of reinforcement was performed using a semi non-destructive galvanostatic pulse method that allows the location of areas of corrosion and estimate the reinforcement corrosion activity. The phase composition of the concrete cover was analyzed. The test results showed an insufficient thickness of the concrete cover as the main cause of loggia wall damage. The research indicated that manufacturing errors made in the prefabrication plants affect the technical condition of precast elements and may lead to the damage of the structure well before the expected of its service life. In the case of manufacturing errors causing the implementation of an element with a concrete cover that does not meet the standard requirements for thickness and tightness, it is recommended to use protective coatings to increase the element’s durability to the designed level.
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Xie, Hu, Bei Jun Zhao, Shi Fu Zhu, Bao Jun Chen, Zhi Yu He, Deng Hui Yang, Wei Huang, Wei Liu, and Zhang Rui Zhao. "Characterization and Vertical Elements Distribution of ZnGeP2 Single Crystals." Key Engineering Materials 680 (February 2016): 493–97. http://dx.doi.org/10.4028/www.scientific.net/kem.680.493.
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A large, crack-free ZnGeP2 single crystal with size of Φ26 mm×70 mm was grown in a vertical three-zone tubular furnace by modified vertical Bridgman method, i.e. real-time temperature compensation technique with small temperature gradient in double-wall quartz ampoule. The as-grown single crystal was characterized by X-ray diffractometer (XRD), energy dispersive spectrometer (EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). It was found that there is a face of (100) and its second-order XRD peaks were observed. The vertical elements distribution of the main part of the grown crystal has a stoichiometric ratio which is close to the ideal stoichiometry of 1:1:2. The IR transmittance of a sample of 2.5 mm thickness is above 58% in the range from 3500 to 800 cm-1. All these results demonstrate that the quality of the ZnGeP2 single crystal grown by the modified method is good, and could be used in the preparation of devices.
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Sun, Ziheng, Liping Di, Sreten Cvetojevic, and Zhiqi Yu. "GeoFairy2: A Cross-Institution Mobile Gateway to Location-Linked Data for In-Situ Decision Making." ISPRS International Journal of Geo-Information 10, no. 1 (December 22, 2020): 1. http://dx.doi.org/10.3390/ijgi10010001.
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To effectively disseminate location-linked information despite the existence of digital walls across institutions, this study developed a cross-institution mobile App, named GeoFairy2, to overcome the virtual gaps among multi-source datasets and aid the general users to make thorough accurate in-situ decisions. The app provides a one-stop service with relevant information to assist with instant decision making. It was tested and proven to be capable of on-demand coupling and delivering location-based information from multiple sources. The app can help general users to crack down the digital walls among information pools and serve as a one-stop retrieval place for all information. GeoFairy2 was experimented with to gather real-time and historical information about crops, soil, water, and climate. Instead of a one-way data portal, GeoFairy2 allows general users to submit photos and observations to support citizen science projects and derive new insights, and further refine the future service. The two-directional mechanism makes GeoFairy2 a useful mobile gateway to access and contribute to the rapidly growing, heterogeneous, multisource, and location-linked datasets, and pave a way to drive us into a new mobile web with more links and less digital walls across data providers and institutions.
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Ukleja, Janusz. "Renovation of the historic building after damage connected with foundations subsidence - case study." MATEC Web of Conferences 174 (2018): 03006. http://dx.doi.org/10.1051/matecconf/201817403006.
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The paper delineates the study of a historic building renovation. It was built in 1900 and completed in 1939. Its both parts consist of different constructions. The old part was founded very deeply whereas the level of the younger part foundations was higher than the old one. After large floods, the walls started to crack, elements of the ceilings and roof under the extended part of the building slipped. It was expected that in the future a construction disaster would pose a serious probability of occurrence. In the study it was necessary to recognize the entire construction with a thorough investigation of the underground, old part of it and also the soil types density were examined. The main objective of the new research was to define the real reasons of the damage and to determine the possibility of repairing this building. The elaboration of the study results revealed a conception of supporting the walls of the building. The results indicated that the need to verify the reasons of the occurring damage in a complex and thorough way is tremendous, especially when a monument is concerned which was developed in stages in various historical periods.
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Szkobodziński, Marcin, and Czesław Miedziałowski. "Vaults, roof truss and walls interaction issue in monumental masonry structures." E3S Web of Conferences 49 (2018): 00113. http://dx.doi.org/10.1051/e3sconf/20184900113.
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The paper discusses the subject of interaction between a roof truss, vaults and load-bearing walls in a masonry monumental structure. The static structural analysis of the Assumption of the Blessed Virgin Mary Basilica in Bialystok, as an example of Polish neogothic architecture from the turn of the 19th and 20th centuries has been carried out. The building consists of a three-aisled masonry walls system, which in cooperation with cross-ribbed vaults and a timber roof truss determine the spatial rigidity of the structure. Lack of concrete ring-beams and horizontal oriented ceiling slabs cause global stiffness reduction to the horizontal loads. In the past, it could have been one of the main reason for the appearance of cracks in the structure. The basic aspect having a real influence on building global behaviour is interaction of load-bearing structural parts. This structure was subjected to the static analysis with an investigation about the influence of interaction between the roof truss, vaults and walls. The values of horizontal displacements of walls were compared as a result of wind pressure acting on the structure. Numerical calculations were carried out using finite element method.
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Suchocki, Czesław, and Wioleta Błaszczak-Bąk. "Down-Sampling of Point Clouds for the Technical Diagnostics of Buildings and Structures." Geosciences 9, no. 2 (January 30, 2019): 70. http://dx.doi.org/10.3390/geosciences9020070.
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Terrestrial laser scanning (TLS) is a non-destructive testing method for the technical assessment of existing structures. TLS has been successfully harnessed for monitoring technical surface conditions and morphological characteristics of historical buildings (e.g., the detection of cracks and cavities). TLS measurements with very high resolution should be taken to detect minor defects on the walls of buildings. High-resolution measurements are mostly needed in certain areas of interest, e.g., cracks and cavities. Therefore, reducing redundant information on flat areas without cracks and cavities is very important. In this case, automatic down-sampling of datasets according to the aforementioned criterion is required. This paper presents the use of the Optimum Dataset (OptD) method to optimize TLS dataset. A Leica ScanStation C10 time-of-flight scanner and a Z+F IMAGER 5016 phase-shift scanner were used during the research. The research was conducted on a specially prepared concrete sample and real object, i.e., a brick citadel located on the Kościuszko Mound in Cracow. The reduction of dataset by the OptD method and random method from TLS measurements were compared and discussed. The results prove that the large datasets from TLS diagnostic measurements of buildings and structures can be successfully optimized using the OptD method.
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Kim, Hyeonmin, Jung-Taek Kim, Jaehyuk Eoh, and Dong-Won Lim. "Development of a Physics-Based Monitoring Algorithm Detecting CO2 Ingress Accidents in a Sodium-Cooled Fast Reactor." Energies 12, no. 1 (December 20, 2018): 1. http://dx.doi.org/10.3390/en12010001.
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One of the benefits of the supercritical CO 2 Brayton cycle in Sodium-cooled Fast Reactors is an enhanced plant safety, since potential reactions of CO 2 with liquid sodium have been reported to be less stringent than a sodium-water reaction found in the Rankine cycle. However, moderate chemical interactions between CO 2 and liquid sodium make detecting CO 2 ingress accidents harder. Thus, this paper proposes a new physics-based detection algorithm by comparing the real-time pressure measurements of two identical heat exchangers for the early detection. The CO 2 ingress occurs owing to a crack at the pressure boundary wall, a certain self-recovery of structural damage does not happen over time, and an accident probabilistically starts at only one component of two. The proposed physics-based method with the probabilistic analysis was compared to the pure data-based method. Finally, the damage degradation was developed with a simplified mass and energy transfer model, and the proposed algorithm was verified with experimental data. The results show that a 99.99% detection probability can be achieved for the air ingress of 30 cc/s, which is equivalent to the 0.12 g/s CO 2 ingress, in a 70 s detection time, limiting down to 0.1% false alarms due to sensor noise.
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Méndez, María Teresa Landa, Ronny Soto Mora, and Luis Gustavo Sosaya del Carpio. "Reinforcement of Adobe Constructions with Toad Rush Mesh." Key Engineering Materials 600 (March 2014): 208–14. http://dx.doi.org/10.4028/www.scientific.net/kem.600.208.
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Peru has a long history of mud constructions. The use of these techniques has been forgotten throughout time, and currently the adobe buildings lack a constructive system suitable for our seismic, economic and ecological characteristics. Current solutions to this problem, including the countrys normative, alter its natural characteristics and make it more expensive. To achieve a way of life that integrates cultural identity, dwelling, environment and health, a natural material of easy acquisition is studied: the toad rush (Juncus bufonius L.) It is a plant that grows in humid areas of the country, between 0 and 4 000 AMSL, in order to address its use as reinforcement in the walls of adobe, based on structural proposals approved in Peru. An experimental methodology has been used under the modality of trial and error. The study was performed in three stages; in the first one, its elasticity coefficient and resistance to traction was determined in laboratory tests. The analysis were performed on simple fibers and braids (of up to 6 fibers), finding the following results: elasticity modulus = 36 kPa with 5% strain, maximum tension stress = 745 N in both directions with 12% elongation. Using these data, an orthogonal mesh of toad rushes, with 0.030 m of separation between braids, was designed to be attached to an adobe wall. This mesh was subjected to a test of horizontal impact, applying 84.49 MPa as a maximum force. In a third stage an adobe module of 2.40 x 2.40 x 2.40 m reinforced with the mesh was subjected to a mechanical seismic simulation test, supporting 26.1 kN without the mesh suffering any damage. As a last test, to comply with the requirements laid down in annex N°1 of the E.080 RNE of the Peruvian standard, a real scale module (2.40 x 2.40 x 2.40 m), was subjected to a cyclic test at the CISMID-UNI laboratory. The results showed that under a distortion from 1/1100 to 1/500 micro cracks were generated in the walls. Under a distortion of 1/400, 0.005 m cracks occurred at the bottom of the north side of the model and under a distortion of 1/280 the model suffered the detachment of the plaster of the lintel, without any damage to the mesh. All the tests allowed for the conclusion that the toad rush (Juncus bufonius L.) is a material that, used as a mesh, can be used asreinforcement in adobe buildings. It is elastic and resistant to traction. It has as an advantage that it is very accessible, known throughout the country and easy to work with. The tests allowed us to proof the resistance of the toad rush mesh, in spite of the features of the adobe not conforming to the Peruvian standard E.080 RNE. We conclude that: it is feasible to use a mesh of toad rush (Juncus bufonius L.) as reinforcement in adobe buildings.
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Wu, Chih-Hang, Hao-Zhi Yan, Li-Fei Liu, and Ruey-Fen Liou. "Functional Characterization of a Gene Family Encoding Polygalacturonases in Phytophthora parasitica." Molecular Plant-Microbe Interactions® 21, no. 4 (April 2008): 480–89. http://dx.doi.org/10.1094/mpmi-21-4-0480.
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Phytophthora parasitica is an oomycete plant pathogen that causes severe disease in a wide variety of plant species. In our previous study, we discovered a multigene family encoding endopolygalacturonases (endoPG) in Phytophthora parasitica. Here, we screened the genomic library of Phytophthora parasitica for the genes encoding endoPG named pppg2 through pppg10, and analyzed their functions. Results obtained by real-time quantitative reverse transcriptase-polymerase chain reaction demonstrated that some of these genes are highly induced during plant infection, which suggests their important roles in the pathogenesis of Phytophthora parasitica. Analysis by in-gel activity assay of recombinant proteins obtained from Pichia pastoris indicated that each of these genes encodes a functional endoPG. Investigation of the function of pppg genes in planta by a Potato virus X agroinfection system in tobacco revealed that each pppg caused specific effects, varying from no symptoms to dwarfism, necrosis, leaf curl, silvery leaf, and cracks in leaf stalks. Appearance of these effects depends on the expression of a pppg protein with a normal active site in the apoplast. These results indicated that each pppg plays a distinct role in the decomposition of plant cell wall.
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Ma, Li, Kemin Li, Shuangshuang Xiao, Xiaohua Ding, and Sydney Chinyanta. "Research on Effects of Blast Casting Vibration and Vibration Absorption of Presplitting Blasting in Open Cast Mine." Shock and Vibration 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/4091732.
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The impact energy produced by blast casting is able to break and cast rocks, yet the strong vibration effects caused at the same time would threaten the safety of mines. Based on the theory of Janbu’s Limit Equilibrium Method (LEM), pseudo-static method has been incorporated to analyze the influence of dynamic loads of blasting on slope stability. The horizontal loads produced by blast vibrations cause an increase in sliding forces, and this leads to a lower slope stability coefficient. When the tensile stresses of the two adjacent blast holes are greater than the tensile strength of rock mass, the radical oriented cracks are formed, which is the precondition for the formation of presplit face. Thus, the formula for calculating the blast hole spacing of presplit blasting can be obtained. Based on the analysis of the principles of vibration tester and vibration pick-up in detecting blast vibrations, a detection scheme of blast vibration is worked out by taking the blast area with precrack rear and non-precrack side of the detection object. The detection and research results of blast vibration show that presplit blasting can reduce the attenuation coefficient of stress wave by half, and the vibration absorption ratio could reach 50.2%; the impact of dynamic loads on the end-wall slope stability coefficient is 1.98%, which proves that presplit blasting plays an important role in shock absorption of blast casting.
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Afanas’ev, A. V., A. A. Mel’nikov, M. I. Vas’kov, and D. N. Bel’kov. "CYCLIC TESTS OF STRESS-CORROSION CRACKS OF STEEL GAS PIPELINE PIPES IN THE ABSENCE OF CORROSIVE ENVIRONMENT." Izvestiya Visshikh Uchebnykh Zavedenii. Chernaya Metallurgiya = Izvestiya. Ferrous Metallurgy 61, no. 8 (October 24, 2018): 589–95. http://dx.doi.org/10.17073/0368-0797-2018-8-589-595.
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The paper presents the results of metallographic studies of stresscorrosion defects (SCC defects) detected on the output gas pipeline of the compressor station. The diagnostics statistics of defects in such pipelines and the data on the effectiveness evaluation of various diagnostic tools during the diagnosis of SCC are given. A presumptive steel grade corresponding to the pipeline metal was identified. The species and morphology of cracks are described. Their character of development is defined. To detect traces of the influence of metallurgical impurities and the external environment on the defects development, a spectrometry of corrosion products and base metal was made. The authors have made the maps of elements distribution over the sample controlled surface. The absence of influence of nonmetallic sulphide inclusions on the development of metal destruction in this is described for the particular case of SCC. It is shown that the sulfur content in corrosion products does not exceed the sulfur content in the sample metal. In some samples, reduced sulfur content can be observed, with the exception of local sites with nonmetallic sulphide inclusions. Electronic images were obtained, which show that these nonmetallic inclusions (in this case) are not sources of cracking development. The results of cyclic tests of samples cut from the pipeline and containing cracks are given. The choice of the cyclic test mode was carried out in accordance with the analysis of the compressor station operating mode for the current year of operation. According to the data received, pipe materials with defects at their initial stage of development have shown considerable durability under test loads. The samples with cracks have withstood from 1.6·106 to 7.5·106 loading cycles under conditions of cyclic transverse bending in the same test plane in the absence of a corrosive medium. In a real gas pipeline under normal operation conditions, the number of such cycles does not exceed 120 – 200 per year, therefore, it can be concluded that the pipeline with defects in their initial stage of development has a significant residual life, provided that its metal wall is reliably protected from effects of corrosive environment.
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Abu-Qudais, M., and D. B. Kittelson. "Experimental and theoretical study of particulate re-entrainment from the combustion chamber walls of a diesel engine." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 211, no. 1 (January 1, 1997): 49–57. http://dx.doi.org/10.1243/0954407971526218.
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The purpose of this research was to investigate the influence of the in-cylinder surfaces on the net emission of the particulate matter in the exhaust of a single cylinder, diesel engine. In order to obtain this information, time-resolved sampling was done to characterize the particulate matter emitted in the engine exhaust. A rotating probe sampled the free exhaust plume once each engine cycle. The rotation of the probe was synchronized with the engine cycle in such a way that the samples could be taken at any predetermined crank angle degree window. The sampling probe was designed for isokinetic sampling in order to obtain reliable results. To characterize the exhaust particulate in real time, a filter for mass concentration measurements was used. The results showed about 45 per cent higher mass concentrations as well as particles of larger diameter emitted during blowdown than late in the displacement phase of the exhaust stroke. This suggests that high in-cylinder shear rates and velocities which are associated with the blowdown process, cause the deposited soot to be re-entrained from the surfaces of the combustion chamber, where re-entrainment is favoured by conditions of high surface shear. A mathematical model to predict the amount of soot re-entrained from the cylinder walls is presented. This model is based on information presented in the literature along with the results of the time-resolved measurements of mass concentration. This model supported the hypothesis of soot deposition during the combustion process, with subsequent re-entrainment during the blowdown process of the exhaust stroke.
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Tej, Petr, and Jiří Kolísko. "Failures of Concrete Slit Drains, Caused by Inappropriate Dilation Material Inserted into Multi-Layer Road Systems." Applied Mechanics and Materials 587-589 (July 2014): 1148–51. http://dx.doi.org/10.4028/www.scientific.net/amm.587-589.1148.
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This paper introduces a real case from construction practice illustrating extensive damage to concrete slit drains, followed by the relevant computer simulation. From the computer simulation and lab tests it follows that the failures of concrete slit drains can be easily caused by deformations of the concrete slabs constituting the surrounding multi-layer road system. Thermally-induced expansions and contractions, as well as concrete shrinkage, produce, in non-dilating connection, stress in the link between the multi-layer road system and the lateral walls of the slit drains. The slit drains are highly sensitive even to a very small malfunction of the expansion joints (e.g. clogging of the slit by solid materials), or their bad installation. It is apparent that failures (cracks) in the slits arise even by the slight compression of a slit drain (to the order of tenths of a millimetre). The analysis presented shows the necessity for a careful installation of expansion joints during the placement of the slit drains into the surrounding multi-layer system, which could induce horizontal pressures on the drains. The study is concluded by recommendations for designers.
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Barton, Colleen A., and Mark D. Zoback. "Discrimination of Natural Fractures From Drilling-Induced Wellbore Failures in Wellbore Image Data - Implications for Reservoir Permeability." SPE Reservoir Evaluation & Engineering 5, no. 03 (June 1, 2002): 249–54. http://dx.doi.org/10.2118/78599-pa.
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Summary Natural fractures and drilling-induced wellbore failures provide critical constraints on the state of in-situ stress and the direct applicability to problems of reservoir production, hydrocarbon migration, and wellbore stability. Acoustic, electrical, and optical wellbore images provide the means to detect and characterize natural fracture systems and to distinguish them from induced wellbore failures. We present new techniques and criteria to measure and characterize attributes of natural and induced fractures in borehole image data. These techniques are applied to the characterization of fracture permeability in two case studies. Introduction Wellbore image logs are extremely useful for identifying and studying a variety of modes of stress-induced wellbore failures. We present examples of how these wellbore failures appear in different types of image data and how they can be discriminated from natural fractures that intersect the wellbore. We then present brief overviews of two studies, which illustrate how the techniques have been applied to address specific issues of fracture permeability. Drilling-induced failures are ubiquitous in oil and gas and geothermal wells because the process of drilling a well causes a concentration of the far-field tectonic stress close to the wellbore, which often can exceed rock strength. Through the use of wellbore imaging and other logging techniques, stress-induced failures can be detected and categorized (compressive, tensile, or shear) and then used to estimate the unknown components of the stress field. We demonstrate how these modes of wellbore failures appear in different types of image data and the pitfalls in their interpretations. The most valuable use of drilling-induced features is to constrain the orientations and magnitudes of the current stress field. The use of drilling-induced features as stress indicators has become routine in the oil and gas industry.1–8 The detection of these features at the wellbore wall has become a primary target for Logging While Drilling/Measurement While Drilling (LWD/ MWD) real-time operations.9 A strong correlation between critically stressed fractures (fractures optimally oriented to the stress field for frictional failure) and hydraulic conductivity has been documented in a variety of reservoirs worldwide.10–12 When faults are critically stressed, permeabilities are increased, and the movement of fluid along faults is possible. We present examples of how knowledge of the stress state and natural fracture population may be used to access reservoir permeability. Drilling-Induced Tensile Wall Fractures Compressive and tensile failure of a wellbore is a direct result of the stress concentration around the wellbore, which results from drilling a well into an already stressed rock mass.13 Compressive wellbore failures (wellbore breakouts), first identified with caliper data, are useful for determining stress orientation in vertical wells.14–16 The study of such features with acoustic and electrical imaging devices makes it possible to clearly identify such features and to use them to determine stress magnitude and stress orientation.15,17–19 It is well known that if a wellbore is pressurized, a hydraulic fracture will form at the azimuth of the maximum horizontal stress.20 The formation of drilling-induced tensile wall fractures is the result of the natural stress state, perhaps aided by drilling-related perturbations, that causes the wellbore wall to fail in tension. The general case of tensile and compressive failure of arbitrarily inclined wellbores in different stress fields is described by Peska and Zoback,1 who demonstrate that there is a wide range of stress conditions under which drilling-induced tensile fractures occur in wellbores, even without a significant wellbore-fluid overpressure. We call these fractures tensile wall fractures because they occur only in the wellbore wall as a result of the stress concentration. These failures form in an orientation of the maximum principal horizontal stress in a vertical borehole (Fig. 1a) and as en echelon features in deviated wells (Fig. 1b). Because drilling-induced tensile wall fractures are very sensitive to the in-situ stress, they can be used to constrain the present state of stress.1,2,21–23 Pitfalls in Interpretation of Tensile Wall Fractures in Wellbore Image Data In cases in which drilling-induced tensile fractures form at an angle to the wellbore axis, it can be difficult to distinguish them from natural fractures, especially in electrical image logs that do not sample the entire wellbore circumference. Because misinterpretation of such features could lead to serious errors in the characterization of a fractured (or possibly not fractured!) reservoir, as well as the assessment of in-situ stress orientation and magnitude, we present criteria that are useful for discriminating natural from induced tensile fractures when observed in wellbore image logs. This is especially important because the wellbore stress concentration can have a significant effect on the appearance of natural fractures that intersect the wellbore. It is well known that fractures are mechanically weakened at their intersection with the borehole. This erosion causes the upper and lower peak and trough of the fracture sinusoid to be enlarged and subsequently enhanced in the standard 2D unwrapped view of wellbore image data (Fig. 2). Where the borehole hoop stress is tensile, the intersection of a natural fracture or foliation plane with the tensile region of the borehole may be preferentially opened in tension (Fig. 3a). These drilling-enhanced natural fractures can be mistaken easily for inclined tensile wellbore failures (Fig. 1b), thus resulting in serious errors in geomechanical modeling. Incipient wellbore breakouts are the early stages of wellbore breakout development, in which the borehole compressive stress concentration has exceeded the rock strength and initiated breakout development. The failed material within the breakout, however, has not yet spalled into the borehole (Fig. 3b). In a vertical borehole, these failures may appear as thin "fractures" that propagate vertically in the borehole and may be confused with drilling induced tensile wall cracks.
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Alejo, David, Fernando Caballero, and Luis Merino. "A Robust Localization System for Inspection Robots in Sewer Networks." Sensors 19, no. 22 (November 13, 2019): 4946. http://dx.doi.org/10.3390/s19224946.
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Sewers represent a very important infrastructure of cities whose state should be monitored periodically. However, the length of such infrastructure prevents sensor networks from being applicable. In this paper, we present a mobile platform (SIAR) designed to inspect the sewer network. It is capable of sensing gas concentrations and detecting failures in the network such as cracks and holes in the floor and walls or zones were the water is not flowing. These alarms should be precisely geo-localized to allow the operators performing the required correcting measures. To this end, this paper presents a robust localization system for global pose estimation on sewers. It makes use of prior information of the sewer network, including its topology, the different cross sections traversed and the position of some elements such as manholes. The system is based on a Monte Carlo Localization system that fuses wheel and RGB-D odometry for the prediction stage. The update step takes into account the sewer network topology for discarding wrong hypotheses. Additionally, the localization is further refined with novel updating steps proposed in this paper which are activated whenever a discrete element in the sewer network is detected or the relative orientation of the robot over the sewer gallery could be estimated. Each part of the system has been validated with real data obtained from the sewers of Barcelona. The whole system is able to obtain median localization errors in the order of one meter in all cases. Finally, the paper also includes comparisons with state-of-the-art Simultaneous Localization and Mapping (SLAM) systems that demonstrate the convenience of the approach.
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Paukštys, Valdas, and Vytautas Stankevičius. "THE ANALYSIS OF SPEED AND PRESSURE OF WIND IN RAINY WEATHER/VĖJO SLĖGIO IR JO GREIČIO KITIMO LYJANT ANALIZĖ." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 7, no. 1 (February 28, 2001): 68–72. http://dx.doi.org/10.3846/13921525.2001.10531701.
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It is not enough to investigate only the effect of wind on buildings, because deterioration of exterior surfaces of buildings is caused by wind and moisture together. A considerable part of rain gets into the exterior surface of enclosure, penetrates deep down and destroys the material of surface layer. The rain passes through enclosure construction and its surface layer due to wind pressure, through joints of the elements and cracks caused by improper transportation as well as by an inaccurate assembling. At present, new multilayer constructional elements are used for building envelope having numerous assembling seams, therefore, the combined influence of rain and wind becomes rather dangerous. It was established that the wind velocity during the rain is one of the main reasons predetermining moisture penetration into protective-decorative walls made of sand-lime brick with split surface, on concrete-lime mortar, according to the analysis of combined influence of the climate by research data [4]. The total effect of rain and wind on the humidity condition of exterior layers is described. Distribution of real wind velocity was estimated according to the data of the last 10 years. It was found that in Kaunas the average wind velocity increases from 3,4 m/s when the rain is absent up to 4,3 m/s and in Vilnius—the average wind velocity increases from 2,9 m/s when the rain is absent up to 3,7 m/s with an increase of approximately 26%, while in Klaipeda the average wind velocity increases from 3,6 m/s when the rain is absent up to 5,1 m/s with an increase of approximately 42%. On the base of the investigations carried out the suggestion is proposed to use the maximum and mean wind velocity values at the rain for estimating the effect of wind to the moisture behaviour in building elements.
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Mathiesen, Tiit. "Do We Really Need Another Journal?" JOURNAL OF GLOBAL NEUROSURGERY 1, no. 1 (April 23, 2021): 16. http://dx.doi.org/10.51437/jgns.v1i1.223.
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A new Journal sees dawn – but didn't we already have too many journals and too many articles published to go to oblivion rapidly? Publishers take advantage of the move towards open access. The need to attract an audience and select papers for high-quality decreases with the move towards business models where journals charge article processing fees to cover expenses and create margins. The Journal of Global Neurosurgery (JGNS) is not a business project: it is far more altruistic and intends to fill a real need. The long-term prospects will not depend on revenue but on the sustainability of the publication model, which by necessity must be low cost and non-profit – other ways, the new journal will not be able to fill the need.
"Global Neurosurgery" is becoming increasingly vogue. Individual neurosurgeons and the World Federation of Neurosurgical Societies have fostered projects to develop our specialty in low- and middle-income countries (LMIC), where single neurosurgeons have catered to many millions of patients. We see a worldwide quiet revolution of expanding surgical infrastructure and dissemination of knowledge in countries previously deprived. The stakeholders of this revolution have soon identified a veritable glass ceiling when it comes to publication. Submissions have frequently been seen as relevant or generalizable for the audiences of existing journals. Clinical neuroscience in LMICs is, much to the surprise of many practitioners and editors in previously established structures, different. Fundamental issues such as study population and external validity were rediscovered when population data, research findings, and practice guidelines from affluent, relatively elderly western people with access to smooth infrastructure and exquisitely equipped hospitals were applied with little meaning in LMICs with different demographics and epidemiology. Yet, many clinical studies from LMICs were adapted to previous literature's format and style, without detecting the unique qualities, "the cracks in the wall" of existing paradigms, that would bring the progress of knowledge and change. I believe that a research community with a thorough understanding of the specific qualities of infrastructure and epidemiology in LMICs is being established, and it needs dedicated platforms. A journal is one such platform that can serve to define and direct the subspecialty.
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Lamparski, Piotr. "Badania georadarowe kemów jako przykład możliwości zastosowania metod geofizycznych do badania form zbudowanych z drobnoziarnistych osadów klastycznych = GPR surveys of kame hills as an example of geophysical methods being applied to the study of forms built of fine grained clastic sediments." Przegląd Geograficzny 92, no. 3 (2020): 423–46. http://dx.doi.org/10.7163/przg.2020.3.7.
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The Ground Penetrating Radar (GPR) method potentially offers many possibilities for fast and reliable lithostratigraphic sediment models to be developed. From a cognitive point of view, this represents a major simplification and shortening of procedures with which information about sediments can be obtained. And from the point of view of the economy of operations, there can be a significant reduction in costs and time of research in shallow geology and the stratigraphy of areas where unconsolidated clastic sediments are of superficial occurrence. Also noteworthy is the possibility for the results of GPR surveys to be deployed in support of geological mapping, as well as in the shallow exploration of resources and hydrogeological studies.The most major advantage of the GPR method related to the possibility of the structure of forms being observed in full shape. In the absence of large outcrops, geophysical prospection of geomorphological forms is helpful, insofar as we are able to translate the results of geophysical surveys into the actual lithostratigraphic system of sediments building a specific form.Against that background, the research presented in this article forms part of the work to develop radar stratigraphy, as an important support for direct geological research (Huggenberger et al., 1994; Van Overmeeren, 1998; Beres et al., 1999, Overgaard and Jakobsen, 2001; Jakobsen and Overgaard, 2002; Neal, 2004; Lejzerowicz et al., 2014; Żuk and Sambrook Smith, 2015; Lejzerowicz et al., 2018). It also points to the research potential of the GPR method in determining the genesis of form. The discussion on the way kames form has been going on in the literature for years (Niewiarowski, 1959; 1961; Karczewski, 1971; Klajnert, 1978; Jaksa, 2003; Terpiłowski, 2008). The studies presented here do not suffice to allow the matter to be determined comprehensively, even though they do provide for verification of the opinions of previous researchers.The area forming the subject of this article is defined by Niewiarowski (1959) as the dead ice zone because of the characteristic set of forms (dead ice moraines, kames and eskers). Like modern researchers (Terpiłowski, 2008), Niewiarowski points to the importance of sub-Quaternary surface elevations in the formation of cracks in the ice sheet, with this leading on to the formation of kame hills above such elevations. This would also seem to have been one of the reasons for the formation in the mass of ice of lakes whose filling with sediment and melting ice walls took the form of kames.The great advantage of the GPR method lies in its ability to recognise macrostructural sediment patterns in glacilimic forms. This diagnosis allows for the high-probability assessment of the genesis of form, especially in the context of its position being determined in the marginal zone of the ice sheet. Also looking extremely promising is the capacity for the thickness of fine clastic sediments lying on till to be determined using GPR. It allows for the determination of the way in which a given form is rooted.Described as they are in brief only, test results for selected sites serve to confirm the great usefulness of the GPR method in the recognition of shallow lithostratigraphy of clastic sediments. Nevertheless, this should not be the only method used to recognise the geological structure of forms and sediments. Significant interpretation ambiguities mean that the GPR method should act in support of direct lithostratigraphic research, not merely serving as an alternative to it. GPR surveys offer a depiction particularly close to the real one – of sediment present in homogeneous sediments in relation to electrical parameters. Sediments ideal for GPR surveys would for example be fine dry sands or silts – and it is precisely these sediments that built most of the investigated kame forms.
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Levy, C., M. Perl, and S. Kotagiri. "The Combined Stress Intensity Factors of Multiple Longitudinally Coplanar Cracks in Autofrettaged Pressurized Tubes Influenced by the Bauschinger Effect." Journal of Pressure Vessel Technology 130, no. 3 (July 11, 2008). http://dx.doi.org/10.1115/1.2937761.
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The influence of the Bauschinger effect (BE) on the three dimensional, Mode I, combined stress intensity factor (SIF) distributions for arrays of longitudinal coplanar, surface cracks emanating from the bore of a fully or partially autofrettaged thick-walled cylinder is investigated. The combined SIFs, KIN, that depend on pressure effects and the “realistic”—Bauschinger effect dependent Autofrettage (BEDA), or, that depend on pressure effects and the “ideal”—Bauschinger effect independent autofrettage (BEIA), are obtained and compared for crack depth to wall thickness, a∕t=0.01–0.25; crack ellipticity, a∕c=0.5–1.5; crack spacing ratio, 2c∕d=0.25–0.75; and autofrettage level, e=30%, 60%, and 100%. The 3D analysis is performed via the finite element method and the submodeling technique, employing singular elements along the crack front. Both autofrettage residual stress fields, BEDA and BEIA, are simulated using an equivalent temperature field. The combined SIF, KIN, is found to vary along the crack front with the maximum determined by the crack ellipticity, crack depth, and crack spacing ratio. For a partially autofrettaged cylinder, the influence of the BE on the combined SIF, KIN, is substantially reduced as the level of overstrain becomes smaller. For some cases, when comparing like crack distributions, the KIN values obtained from the BEDA model are found to be as much as 100% higher than the KIN values that are computed using the BEIA model. A pressurized thick-walled cylinder with BEDA can be most critical when small cracks are farther apart. As crack depth increases, or when the spacing between cracks is smaller, the SIFs increase. Though the differences in the BEDA SIF, KIA, between e=100% and 60% are small (7–15%, in most cases), the increased level of autofrettage produces a 23–30% decrease in the combined SIF values, KIN. In certain cases, the BEIA model implies an infinite fatigue life, whereas the BEDA model for the same parameters implies a finite life. Therefore, it is important to perform a full 3D analysis to determine the real life cycle of the pressurized cylinder for materials that exhibit the BE.
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Moore, S., R. Burrows, D. Kumar, M. B. Kloucek, A. D. Warren, P. E. J. Flewitt, L. Picco, O. D. Payton, and T. L. Martin. "Observation of stress corrosion cracking using real-time in situ high-speed atomic force microscopy and correlative techniques." npj Materials Degradation 5, no. 1 (January 18, 2021). http://dx.doi.org/10.1038/s41529-020-00149-y.
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AbstractContact-mode high-speed atomic force microscopy (HS-AFM) has been utilised to measure in situ stress corrosion cracking (SCC) with nanometre resolution on AISI Type 304 stainless steel in an aggressive salt solution. SCC is an important failure mode in many metal systems but has a complicated mechanism that makes failure difficult to predict. Prior to the in situ experiments, the contributions of microstructure, environment and stress to SCC were independently studied using HS-AFM. During SCC measurements, uplift of grain boundaries before cracking was observed, indicating a subsurface contribution to the cracking mechanism. Focussed ion beam milling revealed a network of intergranular cracks below the surface lined with a thin oxide, indicating that the SCC process is dominated by local stress at oxide-weakened boundaries. Subsequent analysis by atom probe tomography of a crack tip showed a layered oxide composition at the surface of the crack walls. Oxide formation is posited to be mechanistically linked to grain boundary uplift. This study shows how in situ HS-AFM observations in combination with complementary techniques can give important insights into the mechanisms of SCC.
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Daniyan, Ilesanmi, Vincent Balogun, Oghenetano Kilter Ererughurie, Lanre Daniyan, and Bankole Ibrahim Oladapo. "Development of an inline inspection robot for the detection of pipeline defects." Journal of Facilities Management ahead-of-print, ahead-of-print (August 9, 2021). http://dx.doi.org/10.1108/jfm-01-2021-0010.
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Purpose The purpose of this study is to develop a robot for non-destructive testing of the pipelines to improve its reliability and reduce the loss of products due to cracks, corrosions, etc. Design/methodology/approach In this study, an inline inspection robot was developed for crack and corrosion detection in the pipeline. The developed robot consists of ultrasonic sensors to avoid obstacles, a visual aid with high resolution to view real time images and colour sensors for corrosion detection. The Autodesk inventor software was used for the drafting and solid modelling of the robot. A dummy pipe of 500 mm diameter and 2,000 mm length with induced cracks and corrosion was fabricated to test the robot. The colour sensors placed at each side of the robot were used to detect corrosion in the dummy pipe whilst the image processing was done to analyse the crack, as well as the type and depth of corrosion present in the dummy pipe. Findings The results obtained show the ability of the developed robot to detect cracks and determine the crack growth in the pipeline in addition to its ability to determine corrosion. Practical implications Hence, the study provides a diagnostic tool for detecting pipeline defects and analysing the extent of defects to determine the fatigue rate and the useful life of the pipeline. Originality/value The novelties of this study is based on the fact that it was designed to avoid obstacles and check for cracks, leakage and corrosion in pipelines autonomously. It has visual aid that makes it possible to see the interior of the pipe. This makes it easier to identify the defect and the location of the defects before a catastrophic failure. The device is also equipped with sensors, which can detect defects and send the signal to a control system, as well as a Bluetooth device so the operator can have real time information about the state and integrity of the pipelines. The system is also integrated with a Bluetooth device, which permits its compatibility with Android and other mobile applications. Thus, the enabled user can send a command to query the state of the pipeline at any location with the feedback received in the form of short message service. Hence, this study offers contribution in the development of an independent (self-governing) system with the capability to autonomously detect defects in pipe walls and effectively communicate feedback to the authorised users. The prototype model for the evaluation of pipeline integrity will bring about a more proactive way to detect pipeline defects so that effort can be geared towards its restoration before it becomes a major problem, which will subsequently affect productivity and incur losses.
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Silva, Leonardo Martins e., André Luis Christoforo, and Roberto Chust Carvalho. "Calibration of Concrete Damaged Plasticity Model parameters for shear walls." Matéria (Rio de Janeiro) 26, no. 1 (2021). http://dx.doi.org/10.1590/s1517-707620210001.1244.
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ABSTRACT Reinforced concrete structures are relatively complex to analyze, with nonlinear effects like cracking, crushing, steel yielding, aggregate interlock, dowel effect, concrete-rebar interaction and so on. The concrete damaged plasticity CDP model is a consolidated smeared-crack model which accounts for multiaxial behavior with good agreement to experimental results. One particular relevant application which benefits greatly from such feature is the shear wall, as shear stress significantly influences its overall behavior, therefore multiaxial constitutive models and three-dimensional finite elements usage consist in a fitting modeling approach. Reinforced concrete shear walls are structures especially useful for lateral force-resisting systems, as they provide ductility, stiffness and strength. Albeit CDP is widely applied, its parameters are not consensus in the literature, which represents a relevant research gap. The present work considers and compares CDP parameters from relevant literature, in order to calibrate those parameters for the case of reinforced concrete shear walls. To this purpose, four wall experiments related in the bibliography are modeled using solid finite elements for concrete and trusses for rebars using commercial package ABAQUS. All walls are flexure-controlled with aspect ratio greater than 2.0. By varying those parameters and comparing obtained force vs. displacement curves and interesting values attained, like yield lateral force and displacement, stiffness and maximum lateral force, it is settled a set of parameters with acceptable response focusing in the post-peak response based on the lower estimated error of displacement capacity. Those parameters agree reasonably with literature, although it is possible that obtained calibration is restricted to flexure controlled shear walls scope. It is possible that usage of trusses to represent reinforcement does not consider dowel effect, so a suggestion for future studies is to change trusses for elements with transverse stiffness, like beams or solids.
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Mohamed, Anas A., Laith A. Jawad, and Faleh H. Mahmood. "The Use of Ground Penetrating Radar to Assess the Concrete." Iraqi Journal of Science, September 29, 2019, 2095–101. http://dx.doi.org/10.24996/ijs.2019.60.9.25.
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Ground Penetration Radar (GPR) is a modern and promising geophysical technique for near-subsurface exploring and observing because of its characteristic working scheme (instantaneous underground radargram displaying and subsurface features preserving during the detection tests). In this technique a very high and/ or ultra-high electromagnetic radiation frequencies were utilized to be transmitted to the targeted underground area, then the reflected ones which occur because of the sudden changes in the medium electric properties or texture would be recorded and processed to achieve the final GPR radargram.
The main goal of this study is to find out the GPR radiation extension which is suitable for concrete or rebar tiling identifying and measuring in addition to discover the cracks in the concrete walls, the minor goal is studying the effect of GPR device parameters changing on produced radar imagery and identifying the most effective parameter settings for concrete buildings cornerstone locating and wall cracks detection. These parameters are (radiation phase velocity m/sec., frequency coding or sampling, time windows in nano sec., and background removal for unwanted layers removing). The study executed using 1000 MHz antenna on 12 paths and clearly showed that the most important filter/ and or parameter in concrete sites locating and mapping is the "background removal" filter, while other parameters were image improvement ones or sometimes had a negative role in detection procedure.
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Zhang, Yanan, Shengnan Xu, Fan Ji, Yubing Hu, Zhongwei Gu, and Bingqian Xu. "Plant cell wall hydrolysis process reveals structure–activity relationships." Plant Methods 16, no. 1 (November 3, 2020). http://dx.doi.org/10.1186/s13007-020-00691-5.
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Abstract Background Recent interest in Populus as a source of renewable energy, combined with its numerous available pretreatment methods, has enabled further research on structural modification and hydrolysis. To improve the biodegradation efficiency of biomass, a better understanding of the relationship between its macroscopic structures and enzymatic process is important. Results This study investigated mutant cell wall structures compared with wild type on a molecular level. Furthermore, a novel insight into the structural dynamics occurring on mutant biomass was assessed in situ and in real time by functional Atomic Force Microscopy (AFM) imaging. High-resolution AFM images confirmed that genetic pretreatment effectively inhibited the production of irregular lignin. The average roughness values of the wild type are 78, 60, and 30 nm which are much higher than that of the mutant cell wall, approximately 10 nm. It is shown that the action of endoglucanases would expose pure crystalline cellulose with more cracks for easier hydrolysis by cellobiohydrolase I (CBHI). Throughout the entire CBHI hydrolytic process, when the average roughness exceeded 3 nm, the hydrolysis mode consisted of a peeling action. Conclusion Functional AFM imaging is helpful for biomass structural characterization. In addition, the visualization of the enzymatic hydrolysis process will be useful to explore the cell wall structure–activity relationships.
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Chen, Shiming, Bingrui Zhuang, and Ping Gu. "SEISMIC PERFORMANCE EVALUATION OF ASSEMBLED O-STABLE PANEL WALLS." Proceedings of International Structural Engineering and Construction 2, no. 1 (November 2015). http://dx.doi.org/10.14455/isec.res.2015.92.
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O-Stable Panel is a new type of assembled structural wall. To evaluate the performance properties of the O-Stable Panel system, three integral prefabricated panel specimens with different vertical connections at the bottom and one full cast-in-place panel specimen were designed and tested under the low cycle lateral reciprocating loading. The performance of the prefabricated O-Stable Panel systems with different vertical connection configurations was compared with those of the full cast-in-place panel. The investigation reveals that all prefabricated O-Stable panel specimens developed vertical cracks penetrating through thickness of the panels at the panel joint and at the positions where panel thickness variation occurs at the ultimate failure state. The O-Stable panels possess the likely symmetric and stable hysteretic curves and no pinching appearance in shape of the curves. The panel with grouting sleeve in vertical joint for steel rebar appears sharp degrading in seismic index as the lateral drift of the wall increases beyond yield of the panel. For the assembled panel with preinstalled rebar stretched into the foundation beam for the vertical rebar joints, it has very close values in the hysteretic energy dissipation as that in the full cast-in-place panels.