Journal articles: 'Debris morphology'

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Jones, Joshua W., Eugene Chiang, Gaspard Duchêne, Paul Kalas, and Thomas M. Esposito. "Giant Impacts and Debris Disk Morphology." Astrophysical Journal 948, no. 2 (May 1, 2023): 102. http://dx.doi.org/10.3847/1538-4357/acc466.

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Abstract Certain debris disks have nonaxisymmetric shapes in scattered light which are unexplained. The appearance of a disk depends on how its constituent Keplerian ellipses are arranged. The more the ellipses align apsidally, the more nonaxisymmetric the disk. Apsidal alignment is automatic for fragments released from a catastrophic collision between solid bodies. We synthesize scattered light images, and thermal emission images, of such giant impact debris. Depending on the viewing geometry, and if and how the initial apsidal alignment is perturbed, the remains of a giant impact can appear in scattered light as a one-sided or two-sided “fork,” a lopsided “needle,” or a set of “double wings.” The last shape is difficult to reproduce in other scenarios involving gravitational forcing or gas drag, which do not align orbits as well. We compare our images with observations and offer a scorecard assessing whether the scattered light asymmetries in HD 15115, HD 32297, HD 61005, HD 111520, HD 106906, β Pic, and AU Mic are best explained by giant impacts, gravitational perturbations, or sculpting by the interstellar medium.

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Tsunetaka, Haruka, Norifumi Hotta, Yuichi Sakai, and Thad Wasklewicz. "Effect of debris-flow sediment grain-size distribution on fan morphology." Earth Surface Dynamics 10, no. 4 (August 1, 2022): 775–96. http://dx.doi.org/10.5194/esurf-10-775-2022.

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Abstract. Knowledge of how debris flows result in the fan-shaped morphology around a channel outlet is crucial for mitigation of debris-flow-related disasters and investigation of previous sediment transport from the upper channel. Therefore, using a flume connected to a deposition area (inundation plane), this study conducted fan-morphology experiments to assess the effects of differences in grain-size distribution within debris flows on changes in fan morphology. Two types of debris-flow material, i.e., monogranular particles comprising monodispersed sediment particles and multigranular particles comprising polydispersed sediment particles, were used to generate monogranular and multigranular experimental debris flows, respectively. By adjusting the average grain size coincident between the monogranular and multigranular flows, we generated two types of debris flow with similar debris mixture hydrographs but different grain-size distributions in the flume. Although the flow depths were mostly similar between the monogranular and multigranular flows before the start of the debris-flow runout at the deposition area, the runout distances of the front of the multigranular flows were shorter than those of the monogranular flows. The difference in runout distance was responsible for the variations in the extent to and location in which the debris flows changed their direction of descent, resulting in the different shapes and morphologies of the fans in response to grain-size distribution. Although the direction of descent of the flows changed repeatedly, the extent of morphological symmetry of the debris-flow fans increased at a similar time during fan formation irrespective of the grain-size distribution. In contrast to this similarity in the rate of change in fan symmetry, the shift of the multigranular flow directions eventually increased the extent of asymmetry in fan morphology and expanded the scale of deviations in fan morphology between experimental test runs. Therefore, wide-ranging grain-size distributions within debris flows likely result in complex fan morphology with a high degree of asymmetry.

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Pan, Hua Li, Jiang Cheng Huang, Li Qin Wei, and Guo Qiang Ou. "A Study on Scouring Laws Downstream of Debris Flow Sabo Dams." Applied Mechanics and Materials 170-173 (May 2012): 2071–76. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.2071.

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Debris flow sabo dam is one of the most widely used debris flow control engineering. Its stability and safety operation is a key to controlling the effect of hazard prevention and avoiding secondary hazard. Because of the particularity of debris flow, it’s very hard to observe the process and morphology directly by field investigation. Although the scouring depth calculation method in hydraulic engineering provide an idea for debris flow sabo dam, but it can’t be used directly for the calculation of scouring depth downstream of debris flow sabo dams and foundation designation of the control engineering. This paper analyzed the influence factors of scouring laws downstream of debris flow sabo dams and the research status home and abroad. It suggests studying the scouring process and laws downstream of debris flow sabo dams by theoretical analysis, mechanical analysis and energy method combined with simulation experiments, establishing quantitative relationship between the scouring laws, limited depth, morphology, sediment transportation characteristics and the feature parameters of debris flow.

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Li, Yining, and Peilin Zhang. "An online de-noising method for oil ultrasonic wear debris signal: fuzzy morphology component analysis." Industrial Lubrication and Tribology 70, no. 6 (August 13, 2018): 1012–19. http://dx.doi.org/10.1108/ilt-12-2016-0302.

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Purpose In real working condition, signal is highly disturbed and even drowned by noise, which extremely interferes in detecting results. Therefore, this paper aims to provide an effective de-noising method for the debris particle in lubricant so that the ultrasonic technique can be applied to the online debris particle detection. Design/methodology/approach For completing the online ultrasonic monitoring of oil wear debris, the research is made on some selected wear debris signals. It applies morphology component analysis (MCA) theory to de-noise signals. To overcome the potential weakness of MCA threshold process, it proposes fuzzy morphology component analysis (FMCA) by fuzzy threshold function. Findings According to simulated and experimental results, it eliminates most of the wear debris signal noises by using FMCA through the signal comparison. According to the comparison of simulation evaluation index, it has highest signal noise ratio, smallest root mean square error and largest similarity factor. Research limitations/implications The rapid movement of the debris particles, as well as the lubricant temperature, may influence the measuring signals. Researchers are encouraged to solve these problems further. Practical implications This paper includes implications for the improvement in the online debris detection and the development of the ultrasonic technique applied in online debris detection. Originality value This paper provides a promising way of applying the MCA theory to de-noise signals. To avoid the potential weakness of the MCA threshold process, it proposes FMCA through fuzzy threshold function. The FMCA method has great obvious advantage in de-noising wear debris signals. It lays the foundation for online ultrasonic monitoring of lubrication wear debris.

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Jang, J. W., and I. Iwasaki. "Size and morphology of grinding media wear debris." Mining, Metallurgy & Exploration 9, no. 3 (August 1992): 158–60. http://dx.doi.org/10.1007/bf03402989.

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Baker, David M. H., and Lynn M. Carter. "Probing supraglacial debris on Mars 2: Crater morphology." Icarus 319 (February 2019): 264–80. http://dx.doi.org/10.1016/j.icarus.2018.09.009.

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Williams, Paul Allen, and Ian C. Clarke. "Ceramic Wear Debris in Total Joint Replacements: Review of Debris Morphology and Biological Response." Key Engineering Materials 218-220 (November 2001): 591–94. http://dx.doi.org/10.4028/www.scientific.net/kem.218-220.591.

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Wang, Shi Bo, Shi Rong Ge, Hong Tao Liu, and Xiao Long Huang. "Wear Behaviour and Wear Debris Characterization of UHMWPE on Alumina Ceramic, Stainless Steel, CoCrMo and Ti6Al4V Hip Prostheses in a Hip Joint Simulator." Journal of Biomimetics, Biomaterials and Tissue Engineering 7 (October 2010): 7–25. http://dx.doi.org/10.4028/www.scientific.net/jbbte.7.7.

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Ultra-high molecular-weight polyethylene (UHMWPE) has been used in total hip replacement for the last three decades. Despite the advancements in prosthesis design, the wear of UHMWPE remains a serious clinical problem; the release of wear debris may induce osteolysis and implant loosening. Understanding of wear behavior and wear debris morphology of the polyethylene is essential to improve the reliability of hip joint implants. The investigation in this paper carried out wear simulation tests of UHMWPE on Al2O3, 316L stainless steel, CoCrMo alloy and Ti6Al4V alloy, respectively. The lubrication of plasma solution and bovine serum solution was presented in wear tests. The effect of motion and loading on the wear behavior and wear debris morphology, and the influence of femoral head material and assembly style were studied in order to obtain a better understanding of the morphology of ultra-high molecular weight polyethylene wear particles. It is shown that the wear of UHMWPE acetabular cups against metal femoral heads was significantly higher than that against ceramic heads. The presence of protein in lubricant increases the wear of UHMWPE acetabular cups on Al2O3 heads. The wear rates of UHMWPE in multi-directional motion are approximately 2.5 times of those in uni-directional motion. The size distribution range of the UHMWPE debris particles for all head materials varies from submicron particles up to several hundreds micron. The size distribution range of wear debris particles is not directly related to wear resistance of UHMWPE, but significantly influenced by wear mechanisms. The UHMWPE debris particles produced in hip wear simulation tests are classified as round debris, flake-like debris and stick debris, which are closely related to the primary mechanisms of abrasive wear, adhesive wear and fatigue wear.

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Nash, David B. "A general method for morphologic dating of hillslopes." Geology 33, no. 8 (August 1, 2005): 693–95. http://dx.doi.org/10.1130/g21479ar.1.

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Abstract Morphologic dating of hillslopes is the determination of the age of a hillslope by its morphology. Current methods match the observed morphology with the morphology predicted by the diffusion-equation model for hillslope evolution. The morphologic dating method presented here requires no specific model for evolution, but is only applicable to transport-limited hillslopes on which the downslope debris flux is some scale- and time-independent function of slope angle. If these conditions are met, changes in morphology with scale (e.g., height) for a set of hillslopes of a fixed age are identical to changes in morphology with time for a hillslope of a fixed scale. This fact provides the basis for a simple, generally applicable method for morphologically dating such hillslopes with any initial morphology. This new dating method may be applied to a wide variety of vegetated hillslopes in temperate humid regions and is an improvement over previous morphologic dating methods that relied on the diffusion-equation model.

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He, Xiao Ying, Hong Kai Chen, Hong Mei Tang, and Guang Ju Wen. "Formation Mechanism Study on Houchuangzi Slope Debris Flow." Advanced Materials Research 243-249 (May 2011): 3082–86. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.3082.

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Taken the Houchuangzi slope debris flow along Kunming- -Songming highway as instance, analyzed the mineral composition of provenance on the slope debris flow adopted the polycrystal X ray diffractometer, which was rich in hydrophilic clay mineralssuch as kaolinite and montmorillnite; analyzed the fornation mechanism of the HouChuangzi slope debris flow by the laboratory model test, compartmentalized the fornation process of the HouChuangzi slope debris flow in to five stages from the aspects of slope debris flow morphology and crack extension mechanism.The results provide certain reference value for further research of the formation mechanical mechanism.

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11

Cannon, Susan H. "Debris-flow generation from recently burned watersheds." Environmental and Engineering Geoscience 7, no. 4 (November 1, 2001): 321–41. http://dx.doi.org/10.2113/gseegeosci.7.4.321.

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Abstract Evaluation of the erosional response of 95 recently burned drainage basins in Colorado, New Mexico and southern California to storm rainfall provides information on the conditions that result in fire-related debris flows. Debris flows were produced from only 37 of 95 ( approximately 40 percent) basins examined; the remaining basins produced either sediment-laden streamflow or no discernable response. Debris flows were thus not the prevalent response of the burned basins. The debris flows that did occur were most frequently the initial response to significant rainfall events. Although some hillslopes continued to erode and supply material to channels in response to subsequent rainfall events, debris flows were produced from only one burned basin following the initial erosive event. Within individual basin, debris flows initiated through both runoff and infiltration-triggered processes. The fact that not all burned basins produced debris flows suggests that specific geologic and geomorphic conditions may control the generation of fire-related debris flows. The factors that best distinguish between debris-flow producing drainages and those that produced sediment-laden streamflow are drainage-basin morphology and lithology, and the presence or absence of water-repellent soils. Basins underlain by sedimentary rocks were most likely to produce debris flows that contain large material, and sand- and gravel-dominated flows were generated primarily from terrain underlain by decomposed granite. Basin-area and relief thresholds define the morphologic conditions under which both types of debris flows occur. Debris flows containing large material are more likely to be produced from basins without water-repellent soils than from basins with water repellency. The occurrence of sand-and gravel-dominated debris flows depends on the presence of water-repellent soils.

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12

Marston, Richard, and Robin Gray. "Spatial Distribution of Large Woody Debris on the Snake River, Grand Teton National Park." UW National Parks Service Research Station Annual Reports 23 (January 1, 1999): 119–23. http://dx.doi.org/10.13001/uwnpsrc.1999.3385.

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Large woody debris (LWD) plays a key role in controlling the ecology and geomorphology of streams. Woody debris traps coarse particulate organic matter and sediments (Andersen and Sedell, 1979; Bilby and Likens, 1980; Marston, 1982); provides habitat for aquatic insects (Angermeier and Karr, 1984; Benke et al., 1985); and provides cover in pools and slow water areas (Bisson et al., 1982, 1987; Tschaplinski and Hartman, 1983; Fausch and Northcote, 1992). The role of wood in affecting stream morphology is dependent on the size of the stream (Bilby and Ward, 1989). In smaller streams, woody debris can create step pool sequences (Heede, 1972, 1985; Marston, 1982), increase pool area (Murphy and Hall, 1981; Ralph et al., 1994), and reduce sediment transport (Bilby, 1984). Nakamura and Swanson (1993) noted that the importance of woody debris to the morphology of first order streams can be limited by the size of the debris, which is often large enough to bridge the channel and not interact with the flow. Woody debris plays a larger role when it enters the channel bottom, where it can divert flow and affect erosion and deposition. The scale issues raised by Bilby and Ward (1989) and Nakamura and Swanson (1993) are critical to understanding the role of woody debris. To date, LWD has not been adequately studied at watershed scales in larger rivers. In fact, there is little understanding of the relationship between LWD and the geomorphic pattern of the river channel (Piegay and Marston, 1998; Piegay and Gumell, 1997; Piegay, 1993). The purpose of this study is to document the distribution of LWD jams on the Snake River in Grand Teton National Park, Wyoming in order to understand the effects of LWD on channel morphology in large river systems.

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13

Watanabe, O., S. Iwata, and H. Fushimi. "Topographic Characteristics in the Ablation Area of the Khumbu Glacier, Nepal Himalaya." Annals of Glaciology 8 (1986): 177–80. http://dx.doi.org/10.3189/s0260305500001415.

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Topographic sketch mapping of the whole ablation area of the Khumbu Glacier, East Nepal Himalaya, is performed, using a simple, stereo-photogrammetric method. This map shows that the surface morphology can be classified into 11 morphologic characteristics. Depending on their distribution and combination, the ablation area can be divided into four morphologic areas. Detailed maps, on a scale of 1:1000–2500, of these four areas indicate that the distribution and combination of these 11 morphologic characteristics result from thickness of the debris cover, supraglacial streams and ponds, and glacier dynamics. The irregularity in the ablation area of the Khumbu Glacier can be considered to be a consequence of the mass balance between rate of ice charge from upstream and irregular distribution of ablation rate, depending on debris-cover characteristics in situ.

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Watanabe, O., S. Iwata, and H. Fushimi. "Topographic Characteristics in the Ablation Area of the Khumbu Glacier, Nepal Himalaya." Annals of Glaciology 8 (1986): 177–80. http://dx.doi.org/10.1017/s0260305500001415.

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Topographic sketch mapping of the whole ablation area of the Khumbu Glacier, East Nepal Himalaya, is performed, using a simple, stereo-photogrammetric method. This map shows that the surface morphology can be classified into 11 morphologic characteristics. Depending on their distribution and combination, the ablation area can be divided into four morphologic areas. Detailed maps, on a scale of 1:1000–2500, of these four areas indicate that the distribution and combination of these 11 morphologic characteristics result from thickness of the debris cover, supraglacial streams and ponds, and glacier dynamics. The irregularity in the ablation area of the Khumbu Glacier can be considered to be a consequence of the mass balance between rate of ice charge from upstream and irregular distribution of ablation rate, depending on debris-cover characteristics in situ.

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Baselt, Ivo, Gustavo Q. de Oliveira, Jan-Thomas Fischer, and Shiva P. Pudasaini. "Deposition morphology in large-scale laboratory stony debris flows." Geomorphology 396 (January 2022): 107992. http://dx.doi.org/10.1016/j.geomorph.2021.107992.

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Zolotarevova, E., Z. Fejfarkova, G. Entlicher, M. Lapcikova, M. Slouf, D. Pokorny, and A. Sosna. "Can centrifugation affect the morphology of polyethylene wear debris?" Wear 265, no. 11-12 (November 2008): 1914–17. http://dx.doi.org/10.1016/j.wear.2008.04.005.

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Cho, Unchung, and John A. Tichy. "Quantitative correlation of wear debris morphology: grouping and classification." Tribology International 33, no. 7 (July 2000): 461–67. http://dx.doi.org/10.1016/s0301-679x(00)00074-8.

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Cherry, J., and R. L. Beschta. "COARSE WOODY DEBRIS AND CHANNEL MORPHOLOGY: A FLUME STUDY." Journal of the American Water Resources Association 25, no. 5 (October 1989): 1031–36. http://dx.doi.org/10.1111/j.1752-1688.1989.tb05417.x.

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Hendel, David, and Kathryn V. Johnston. "Tidal debris morphology and the orbits of satellite galaxies." Monthly Notices of the Royal Astronomical Society 454, no. 3 (October 13, 2015): 2472–85. http://dx.doi.org/10.1093/mnras/stv2035.

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Zhou, Gordon G. D., Shuai Li, Dongri Song, Clarence E. Choi, and Xiaoqing Chen. "Depositional mechanisms and morphology of debris flow: physical modelling." Landslides 16, no. 2 (November 7, 2018): 315–32. http://dx.doi.org/10.1007/s10346-018-1095-9.

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Vere, D. M., and D. I. Benn. "Structure and Debris Characteristics of Medial Moraines in Jotunheimen, Norway: Implications for Moraine Classification." Journal of Glaciology 35, no. 120 (1989): 276–80. http://dx.doi.org/10.3189/s0022143000004615.

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Abstract Four medial moraines on three glaciers in Jotunheimen, Norway, are described. The structure and debris characteristics of the moraines allow three debris-transport routes to be identified: (1) discrete concentrated longitudinal septa containing subglacially comminuted debris; (2) diffuse longitudinal septa containing passively englacially transported debris; and (3) supraglacially transported spreads containing rock-fall debris entrained below the firn line. Two of the moraines, occurring down-glacier of nunataks, are nourished by a combination of (1) and (3). The remaining two moraines are nourished solely by englacially transported rock-fall debris (2). Transport routes (1) and (2) represent two distinct types of longitudinal englacial debris septum. The contribution of debris from more than one glacial transport path to single medial moraines indicates the value of a flexible, process-based approach towards moraine classification, with emphasis on the dynamic links between basin morphology, glacial debris entrainment, and moraine characteristics.

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Florian, Camilo, Yasser Fuentes-Edfuf, Evangelos Skoulas, Emmanuel Stratakis, Santiago Sanchez-Cortes, Javier Solis, and Jan Siegel. "Influence of Heat Accumulation on Morphology Debris Deposition and Wetting of LIPSS on Steel upon High Repetition Rate Femtosecond Pulses Irradiation." Materials 15, no. 21 (October 25, 2022): 7468. http://dx.doi.org/10.3390/ma15217468.

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The fabrication of laser-induced periodic surface structures (LIPSS) over extended areas at high processing speeds requires the use of high repetition rate femtosecond lasers. It is known that industrially relevant materials such as steel experience heat accumulation when irradiated at repetition rates above some hundreds of kHz, and significant debris redeposition can take place. However, there are few studies on how the laser repetition rate influences both the debris deposition and the final LIPSS morphology. In this work, we present a study of fs laser-induced fabrication of low spatial frequency LIPSS (LSFL), with pulse repetition rates ranging from 10 kHz to 2 MHz on commercially available steel. The morphology of the laser-structured areas as well as the redeposited debris was characterized by scanning electron microscopy (SEM) and µ-Raman spectroscopy. To identify repetition rate ranges where heat accumulation is present during the irradiations, we developed a simple heat accumulation model that solves the heat equation in 1 dimension implementing a Forward differencing in Time and Central differencing in Space (FTCS) scheme. Contact angle measurements with water demonstrated the influence of heat accumulation and debris on the functional wetting behavior. The findings are directly relevant for the processing of metals using high repetition rate femtosecond lasers, enabling the identification of optimum conditions in terms of desired morphology, functionality, and throughput.

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Lv, Li Qun, Ning Sheng Chen, Yang Lu, Qi Huang, Jun Li, and Yun Hua Zhu. "Characteristics and Mechanics Analysis of Debris Flow Disaster in Xinjiang Arid Area." Advanced Materials Research 594-597 (November 2012): 2318–22. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.2318.

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Xinjiang arid area is characterized by low rainfall, strong evaporation capacity, sparse vegetation, intensive tectonic movement, and fragile ecological environment ; the rainfall-type debris flow in the arid area are obviously different from the same type debris flow in humid and subhumid area of China with conditions of rainfall excitation, watershed morphology, motion and deposition processes, material composition, active period and disaster mechanism. Investigations and analyses of characteristics of rainfall-type debris flow in the arid area will reveal the rule of the occurrence and development and explore the evolution trends, to establish reasonable disaster reduction measures. Qiaoquli gully located in Kashgar is a typical arid area rainfall debris flow gully. The 50-year frequency outbreak of debris flow in 2005 destroyed chinapakistan highway . Further investigation to this debris flow gully will contribute to our understanding of this kind of debris flow disaster characteristics and mechanism.

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Pérez, Francisco L. "Talus fabric, clast morphology, and botanical Indicators of Slope Processes on the Chaos Crags (California Cascades), U.S.A." Géographie physique et Quaternaire 52, no. 1 (October 2, 2002): 47–68. http://dx.doi.org/10.7202/004861ar.

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AbstractThe Chaos Crags, a group of dacite domes in the Cascades Mtns (California), were affected by volcanic debris avalanches ca. 1675 A.D.; these left a sizable deposit and a scar on the north mountain flank, now covered by talus. This report examines the fabric and morphology of talus debris, their spatial variation, and the geomorphic processes presently affecting the slope. The talus presents a bi-segmented profile with a steep upper rectilinear segment and a shorter concave, basal zone. Debris are sorted by size both along (larger clasts downslope) and across the talus (larger particles below the cliffs). Shape sorting is weaker, but clast sphericity increases, and elongation decreases, toward the footslope. Upper-talus fabrics (long axes parallel to talus plane and slope) show that clasts there move by sliding, while basal blocks are deposited by rockfall, which causes more iso- tropic fabrics. Field observations and botanical evidence indicate the overall significance of grain flows, which are prevalent duetoanabundantsupplyofrubbleonthe upper talus. Comparison with similar recent slopes and repeat photography suggest the Chaos talus formed swiftly following dome collapse, when much debris may have collected below the unstable rockwalls. The talus has experienced only modest sedimentation during the 20thcentury, and is currently affected by 'normal' mass-wasting processes, which also include snow avalanches and debris flows.

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Dong, Yi, Feng Mao, Jiaying Cao, Qi Zhang, Daohui Yang, Wen-Ping Wang, and Christoph F. Dietrich. "Differential diagnosis of gallbladder ascariasis debris: the added value of contrast enhanced ultrasound with high frequency transducer." Medical Ultrasonography 20, no. 4 (December 8, 2018): 413. http://dx.doi.org/10.11152/mu-1750.

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Ascariasis debris of the gallbladder is a very rare incidental or symptomatic presentation. Ascaris debris has a pseudotumorous appearance and may be confused with neoplasia. The aim of the current retrospective study is to investigate the value of contrast enhanced ultrasound (CEUS) for the differential diagnosis of ascariasis debris and neoplasia of the gallbladder.Material and methods: Conventional B-mode ultrasound (BMUS) and CEUS were performed for solitary echo-rich gallbladder lesions. Analysis of the CEUS enhancement pattern of the lesions was conducted according to the current EFSUMB guidelines. Two radiologists assessed the CEUS enhancement patterns in consensus. The final gold standard was surgery with histological examination or imaging follow-up.Results: A total of 9 patients with final diagnoses of gallbladder ascariasis debris were included. As a control group 26 solitary hyperechoic gallbladder lesions without shadowing were included as a control group. The typical zigzag morphology with multiple echogenic parallel lines without shadow were detected inside the lumen of the gallbladder in 6 patients. After injection of 2.4 ml ultrasound contrast agents, all hyperechoic gallbladder ascariasis debris lesions showed no enhancement. All patients in the control group with similar BMUS morphology showed contrast enhancement.Conclusions: Real time visualization of contrast enhancement without radiation exposure is one of the main advantages of CEUS over other diagnostic modalities to differentiate ascariasis debris in the gallbladder from enhancing neoplasia. Thus, surgery and other interventions and their complications could be avoided.

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Guo, Yan Ying, and Zhi Gang Liu. "Airport Runway Debris Edge Detection Algorithm." Advanced Materials Research 1065-1069 (December 2014): 671–74. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.671.

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Airport runway debris detection decides security of plane and passengers. The relative merits of the various types of sensor and the effects of adverse environmental conditions on their performance, a novel fuzzy weighted morphology algorithm of detection about runway debris is approved. The experimental results show that the proposed algorithm, compared with a few classic algorithms of edge detection, which can achieves the image edge precisely and reduce noises, better retain the image details, and adaptively detect the complete and successive edges.

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Xu, Xiulin, Xing Lu, Zuoxiang Qin, and Dalong Yang. "The study of friction layer and tribological property of PI–matrix composites." Industrial Lubrication and Tribology 69, no. 2 (March 13, 2017): 267–75. http://dx.doi.org/10.1108/ilt-02-2016-0035.

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Purpose This paper aims to study the friction layer and tribological property of polyimide (PI)–matrix composites under different friction speeds. Design/methodology/approach Friction tests were conducted under friction speeds ranging from 20-120 km/h and pressure of 0.57 MPa by a pin-on-disk tribometer. Findings The results indicate that the friction coefficient decreases with the increasing of the friction speed. Under different friction speeds, the structure of the friction layer and debris are different, which affects the actual tribological performance of the composites. At low friction speed, the morphology of the friction layer is mainly particulate. The higher level of clenching action between the friction pair leads to a high friction coefficient, and the morphology of the particles in the particulate zone and the wear debris are mostly equiaxial particles. At high friction speed, the morphology of the friction layer is mainly a compact zone. The reduction of the surface roughness leads to a low friction coefficient. The debris collected on the counter surface at high friction speeds are mostly big sheets, and the morphology of the particles in the particulate zone is mostly rod-like. Controlling the conditions of the disk and the pin can reveal the influence of friction speed on the friction layer. The wear mechanisms at different friction speeds are also discussed. Originality/value By controlling the conditions of the disk and the pin to reveal the influence of friction speed on the friction layer, and the evolutions of the friction layer, wear debris were carefully inspected with the aim of demonstrating the relationship between friction speed and wear mechanism of PI–matrix composites.

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Hayakawa, Yuichi S., Hidetsugu Yoshida, Hiroyuki Obanawa, Ryutaro Naruhashi, Koji Okumura, Masumi Zaiki, and Ryoichi Kontani. "Characteristics of debris avalanche deposits inferred from source volume estimate and hummock morphology around Mt. Erciyes, central Turkey." Natural Hazards and Earth System Sciences 18, no. 2 (February 7, 2018): 429–44. http://dx.doi.org/10.5194/nhess-18-429-2018.

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Abstract. Debris avalanches caused by volcano sector collapse often form characteristic depositional landforms such as hummocks. Sedimentological and geomorphological analyses of debris avalanche deposits (DADs) are crucial to clarify the size, mechanisms, and emplacement of debris avalanches. We describe the morphology of hummocks on the northeastern flank of Mt. Erciyes in Kayseri, central Turkey, likely formed in the late Pleistocene. Using a remotely piloted aircraft system (RPAS) and the structure-from-motion and multi-view stereo (SfM–MVS) photogrammetry, we obtained high-definition digital elevation model (DEM) and orthorectified images of the hummocks to investigate their geometric features. We estimated the source volume of the DAD by reconstructing the topography of the volcano edifice using a satellite-based DEM. We examined the topographic cross sections based on the slopes around the scar regarded as remnant topography. Spatial distribution of hummocks is anomalously concentrated at a certain distance from the source, unlike those that follow the distance–size relationship. The high-definition land surface data by RPAS and SfM revealed that many of the hummocks are aligned toward the flow direction of the debris avalanche, suggesting that the extensional regime of the debris avalanche was dominant. However, some displaced hummocks were also found, indicating that the compressional regime of the flow contributed to the formation of hummocks. These indicate that the flow and emplacement of the avalanche were constrained by the topography. The existing caldera wall forced the initial eastward flow to move northward, and the north-side caldera wall forced the flow into the narrow and steepened outlet valley where the sliding debris underwent a compressional regime, and out into the unconfined terrain where the debris was most likely emplaced on an extensional regime. Also, the estimated volume of 12–15 × 108 m3 gives a mean thickness of 60–75 m, which is much deeper than the reported cases of other DADs. This suggests that the debris avalanche must have flowed further downstream and beyond the current DAD extent. Assessments of the DAD incorporating the topographic constraints can provide further insights into the risk and mitigation of potential disasters in the study area.

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Beravala, Hardik, and Pulak M. Pandey. "Characterization of Debris Formed in Magnetic Field-Assisted EDM Using Two-Phase Dielectric Fluid." Journal of Advanced Manufacturing Systems 19, no. 04 (December 2020): 629–40. http://dx.doi.org/10.1142/s0219686720500353.

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The present research was focussed to investigate the influence of liquid-gaseous dielectric on debris formation in magnetic field-assisted electrical discharge machining. The air and argon gas were used to make two-phase dielectric fluids such as liquid-air and liquid-argon gas, respectively. Experimentation was conducted to compare the effect of different liquid-gaseous dielectric environments on debris formation. The morphology and diameter distribution of debris were analyzed. In addition, the effect on elemental analysis, phase transformation and magnetic property of debris was investigated. The experimental results showed the exothermic reaction due to air from liquid–air dielectric, and inert property of argon gas from liquid-gaseous dielectric affected the formation of debris. The XRD results confirmed the formation of oxides in the debris produced using liquid-air mixed dielectric. The oxide-free debris formed while using the argon gas. Low saturation of magnetization was found in the debris, formed in the liquid–air dielectric which showed the weak attraction toward magnet when compared with that in the liquid–argon gas mixed dielectric.

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Khan, M. A., A. G. Starr, and D. Cooper. "A methodology for online wear debris morphology and composition analysis." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 222, no. 7 (July 2008): 785–96. http://dx.doi.org/10.1243/13506501jet449.

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Boccaletti, A., J. C. Augereau, A. M. Lagrange, J. Milli, P. Baudoz, D. Mawet, D. Mouillet, J. Lebreton, and A. L. Maire. "Morphology of the very inclined debris disk around HD 32297." Astronomy & Astrophysics 544 (August 2012): A85. http://dx.doi.org/10.1051/0004-6361/201219320.

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Ilstad, Trygve, Fabio V. De Blasio, Anders Elverhøi, Carl B. Harbitz, Lars Engvik, Oddvar Longva, and Jeffrey G. Marr. "On the frontal dynamics and morphology of submarine debris flows." Marine Geology 213, no. 1-4 (December 2004): 481–97. http://dx.doi.org/10.1016/j.margeo.2004.10.020.

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Abe, Shigeaki, Nobuki Iwadera, Mitsue Esaki, Ken-Ichi Aoyama, Tsukasa Akasaka, Motohiro Uo, Manabu Morita, Yasutaka Yawaka, and Fumio Watari. "Morphology, size distribution and elemental composition of several dental debris." Applied Surface Science 262 (December 2012): 248–52. http://dx.doi.org/10.1016/j.apsusc.2012.07.126.

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Masson, Canals, Alonso, Urgeles, and Huhnerbach. "The Canary Debris Flow: source area morphology and failure mechanisms." Sedimentology 45, no. 2 (March 1998): 411–32. http://dx.doi.org/10.1046/j.1365-3091.1998.0165f.x.

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Hosseini, S. M., and T. A. Stolarski. "Morphology of polymer wear debris resulting from different contact conditions." Journal of Applied Polymer Science 45, no. 11 (August 15, 1992): 2021–30. http://dx.doi.org/10.1002/app.1992.070451116.

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Zhang, S., L. M. Zhang, and H. X. Chen. "Relationships among three repeated large-scale debris flows at Pubugou Ravine in the Wenchuan earthquake zone." Canadian Geotechnical Journal 51, no. 9 (September 2014): 951–65. http://dx.doi.org/10.1139/cgj-2013-0368.

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The 12 May 2008 Wenchuan earthquake in China triggered numerous landslides. Loose landslide materials can easily evolve into deadly debris flows during wet seasons. During the period from 2008 to 2011, three separate large-scale debris flows occurred in the Pubugou Ravine near the epicentre of the earthquake that were among the largest repeated debris flows ever reported. Approximately 1.76 × 106 m3 of sediment was deposited during these three events. This paper aims to (i) analyze the movements of solid materials during the repeated debris flows, (ii) discuss the evolution of the initiation mechanisms of these debris flows, and (iii) evaluate the changing depositional morphology of the debris flow fans and examine the particle sizes of the debris flow materials. To achieve the above research objectives, timely field investigations were undertaken in the past 5 years after each of these debris flow events. Satellite images were used to delineate the boundaries of the initiation areas, the transportation channels, and the deposition zones of these debris flows. With the occurrence of the repeated debris flows, the hill slope deposits gradually evolved into channel deposits and the solid materials in the channels moved toward the gully mouth. Hence, channelized flows gradually became dominant. The debris fan materials of the repeated debris flows became coarser and coarser over time. The three debris flows were all characterized by coarse boulder fronts.

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Samyn, Pieter, Alessandro Ledda, Jan Quintelier, Isabel Van Driessche, Gustaaf Schoukens, Patrick de Baets, and Wim De Waele. "A Combination of Mathematical Morphology and Thermal Analysis of Wear Debris Explaining Polymer Sliding Mechanisms." Materials Science Forum 561-565 (October 2007): 2237–40. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.2237.

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Polymer wear debris particles undergo a thermal and mechanical (shear) cycle since their generation and therefore contain information on the friction and wear processes, while it is often difficult to draw quantitative data from them relating to transitions in tribological behaviour. Results from thermal DTA/TGA analysis and morphological pattern spectra of debris are presented and related to a transition at 180°C sliding temperatures own to hydrolysis and imidisation.

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Lestari, W. D., R. Ismail, J. Jamari, and A. P. Bayuseno. "Study on Wear Debris Characterization of Polycarbonate Urethane (PCU) as a Bearing of Artificial Hip Joint." Journal of Physics: Conference Series 2065, no. 1 (November 1, 2021): 012004. http://dx.doi.org/10.1088/1742-6596/2065/1/012004.

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Abstract As with all artificial joints, wear debris is of particular concern due to its effect on both implant life and the in vivo biological reactions that can occur. The purpose of the research is to study debris characterization of PCU. Wear particle is produced from testing the PCU material using a pin on disc wear tester within 50000 cycles. This study showed that the PCU wear debris gotten from the simulator had various different shapes, including laminar and spherical types. The morphology of worn surface and wear debris analysis showed that wear mechanism of PCU were fatigue wear. Thus we conclude that PCU is expected to be a lifetime implantation of artificial joint.

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Prati, Carlo, Fausto Zamparini, Andrea Spinelli, Gian Andrea Pelliccioni, Chiara Pirani, and Maria Giovanna Gandolfi. "Secondary Root Canal Treatment with Reciproc Blue and K-File: Radiographic and ESEM-EDX Analysis of Dentin and Root Canal Filling Remnants." Journal of Clinical Medicine 9, no. 6 (June 18, 2020): 1902. http://dx.doi.org/10.3390/jcm9061902.

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Secondary root canal treatment requires the complete removal of filling materials with different chemical-physical properties. A newly developed single-use NiTi instrument (Reciproc Blue, RB) may be more effective in root canal retreatment. The aim of the present study was to evaluate morphology and composition of remnants after retreatment with RB compared to traditional K-File technique, in canals obturated with Thermafil/AH Plus. Twenty-four single-rooted human teeth were shaped with NiTi obturated with AH-Plus/Thermafil and retreated using RB NiTi instruments or manual K-Files. Radiographs were taken to evaluate endodontic space and radiopacity of residual filling-material before/after procedures. After retreatment, samples were longitudinally split and observed by environmental scanning electron microscopy connected to energy dispersive X-Ray spectroscopy (ESEM-EDX) to analyze the debris/remnant position, microchemistry, and dentinal surface morphology. Time for retreatments was recorded and compared using one-way ANOVA (p-value = 0.05). Radiopaque filling residuals were found in both groups. RB system resulted statistically faster than manual K-File in retreatment procedure (p < 0.001). Root canal space radiographic appearance obtained after retreatment with RB was wider than K-File (p < 0.05). ESEM-EDX revealed 4 different morphological dentin area. Area-1: debris-free with typical Ca, P, and N composition of dentin and detected in 70% of the surface. Area-2: presence of deproteinized smear layer free from N and debris in 15% of the surface. Area-3: a thick packed smear layer N-free and with fine debris consisting of trace elements from sealer in 10% of the surface. Area-4: packed with debris and trace elements. No difference was observed between both instruments regarding root canal space appearance and ESEM-EDX analysis. Both systems were able to remove filling material but created a dentine morphology composed of packed debris and filling materials embedded into the smear layer. Dentin surface composition resulted in collagen depleted by irrigation procedures. The reciprocating system required less time to complete retreatment.

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Wu, Jianzhao, Aibing Yu, Qiujie Chen, Maochao Wu, Lei Sun, and Jiandong Yuan. "Tribological properties of bronze surface with dimple textures fabricated by the indentation method." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 234, no. 10 (July 12, 2020): 1680–94. http://dx.doi.org/10.1177/1350650120940126.

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Surface texturing is an effective approach to improve the tribological properties of mechanical components. An indentation method is presented to fabricate dimple textures on bronze specimen surfaces. Graphite was selected as the mating balls in ball-on-disc wear tests. The worn surfaces and the indented dimples heaped with the thin ribbon debris were observed by microscope. The morphology and evolution of wear debris were employed to explain the influence of indented dimple textures. The experimental results indicate that the generation of thin ribbon debris is due to the edge hardening of indented dimple. The thin ribbon debris and the indented conical dimple are conducive to the debris heaping on slopes of dimples, which can facilitate the formation of the graphite-rich transfer layers on indented dimple surface. Compared with nontextured surface, indented dimple surface has lower coefficients of friction and slighter wear. The tribological properties of indented dimple surface are improved because of the edge hardening, the debris heaping and the formation of transfer layers.

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Smiraglia, C. "The Medial Moraines of Ghiacciaio Dei Forni, Valtellina, Italy: Morphology and Sedimentology." Journal of Glaciology 35, no. 119 (1989): 81–84. http://dx.doi.org/10.3189/002214389793701428.

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AbstractTwo distinct medial moraines are located on the tongue of Ghiacciaio dei Forni (Rhaetian Alps, Italy); they are formed by the confluence of three ice streams. The two ice-cored medial moraines originate from rock outcrops situated below the snow line. The moraines, which on the surface comprise angular clasts, extend for approximately 2 km and reach a maximum height of 10 m. Nourishment of the moraines seems to be due primarily to the supraglacial debris derived from the rock walls. Measurements made in the late summer of 1985 provided evidence of the role played by differential ablation in the development of these moraines. Sedimentological analysis further confirmed the mainly supraglacial origin of the debris comprising the moraines.

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Feng, Cunao, Yujie Zhao, Tao Zhang, Kai Chen, Xiaowei Li, and Dekun Zhang. "Separation and Extraction of Mixed Grinding Chips of Artificial Joints with Different Densities by Multiple Centrifugal Separations." Lubricants 10, no. 9 (September 19, 2022): 226. http://dx.doi.org/10.3390/lubricants10090226.

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Aseptic loosening caused by the wear and tear of the artificial joint prosthesis after implantation is one of the main causes of artificial joint failure. Therefore, it is important to investigate the wear debris generated due to wear when developing new artificial joint materials. Aseptic loosening is related to the size, number, and morphology of wear debris, and this study proposed the separation and extraction of mixed wear debris with different density ratios of artificial joints by centrifugation to study the characteristics of different artificial joint wear and wear debris extraction rates. The results showed that multiple centrifugations to separate the mixed wear debris were able to reintroduce the wear debris on the wall of the centrifuge tube into the solution and that the wear debris extraction rate was increased. Suspensions with different density ratios of artificially jointed mixed wear debris were effectively separated by this method. The total extraction rate of the three repeated extractions compared to the first extraction rate, the extraction rate of CoCrMo wear debris increased by 6.7%, ultra-high molecular weight polyethylene (UHMWPE) wear debris increased by 15.1–23.44%, ZrO2 wear debris increased by 10.91%, and that of polyether ether ketone (PEEK) wear debris increased by 9.95%. This method for separating and extracting wear debris from artificial joints can realize the separation of mixed wear debris from artificial joints and obtain a high extraction rate and high-quality wear debris images, investigate the wear mechanism of artificial joint implants, and provide valuable information on the wear performance of new artificial joint implants under investigation.

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Hopkins, Nathan R., Edward B. Evenson, Dario Bilardello, Richard B. Alley, Claudio Berti, and Kenneth P. Kodama. "Magnetic anisotropy and debris-dependent rheological heterogeneity within stratified basal ice." Journal of Glaciology 65, no. 253 (September 5, 2019): 770–79. http://dx.doi.org/10.1017/jog.2019.51.

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AbstractBasal ice of glaciers and ice sheets frequently contains a well-developed stratification of distinct, semi-continuous, alternating layers of debris-poor and debris-rich ice. Here, the nature and distribution of shear within stratified basal ice are assessed through the anisotropy of magnetic susceptibility (AMS) of samples collected from Matanuska Glacier, Alaska. Generally, the AMS reveals consistent moderate-to-strong fabrics reflecting simple shear in the direction of ice flow; however, AMS is also dependent upon debris content and morphology. While sample anisotropy is statistically similar throughout the sampled section, debris-rich basal ice composed of semi-continuous mm-scale layers (the stratified facies) possesses well-defined triaxial to oblate fabrics reflecting shear in the direction of ice flow, whereas debris-poor ice containing mm-scale star-shaped silt aggregates (the suspended facies) possesses nearly isotropic fabrics. Thus, deformation within the stratified basal ice appears concentrated in debris-rich layers, likely the result of decreased crystal size and greater availability of unfrozen water associated with high debris content. These results suggest that variations in debris-content over small spatial scales influence ice rheology and deformation in the basal zone.

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Berg, Neil, Ann Carlson, and David Azuma. "Function and dynamics of woody debris in stream reaches in the central Sierra Nevada, California." Canadian Journal of Fisheries and Aquatic Sciences 55, no. 8 (August 1, 1998): 1807–20. http://dx.doi.org/10.1139/f98-064.

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In 1993, we located, measured, and tagged almost 1700 woody debris pieces on six streams in Californias central Sierra Nevada. The stability, geomorphic function, and use by fish for cover of each piece were recorded. In 1994 and 1995, piece movement was quantified and new debris pieces were measured. In the 60 study reaches, debris was not influential in shaping channel morphology and fish cover. Although woody debris was often associated with habitat units, few pieces deflected flow or contributed to the formation of pools or steps. Fish used deep water as cover more often than debris or any other cover type. Medium-sized debris was, however, used in a greater proportion than its availability to fish. Little sediment was stored by debris, and five large pieces stored 85% of the sediment volume measured. Debris frequency and volume did not differ significantly by channel type. After a low stream flow year (19931994), few pieces had moved and few new pieces were identified. After a high-flow season (19941995), 31% of the pieces had either moved or were not found and new pieces represented over 5% of the originally surveyed volume of wood.

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Hailey, J. L., E. Ingham, M. Stone, B. M. Wroblewski, and J. Fisher. "Ultra-High Molecular Weight Polyethylene Wear Debris Generated in Vivo and in Laboratory Tests; the Influence of Counterface Roughness." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 210, no. 1 (March 1996): 3–10. http://dx.doi.org/10.1243/pime_proc_1996_210_385_02.

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The objective of this study was to investigate the effect of counterface roughness and lubricant on the morphology of ultra-high molecular weight polyethylene (UHMWPE) wear debris generated in laboratory wear tests, and to compare this with debris isolated from explanted tissue. Laboratory tests used UHMWPE pins sliding against stainless steel counterfaces. Both water and serum lubricants were used in conjunction with rough and smooth counterfaces. The lubricants and tissue from revision hip surgery were processed to digest the proteins and permit filtration. This involved denaturing the proteins with potassium hydroxide (KOH), sedimentation of any remaining proteins, and further digestion of these proteins with chromic acid. All fractions were then passed through a 0.2 μm membrane, and the debris examined using scanning electron microscopy. The laboratory studies showed that the major variable influencing debris morphology was counterface roughness. The rougher counter-faces produced larger numbers of smaller particles, with a size range extending below 1 μm. For smooth counterfaces there were fewer of these small particles, and evidence of larger platelets, greater than 10 μm in diameter. Analysis of the debris from explanted tissues showed a wide variation in the particle size distribution, ranging from below 1 μm up to several millimetres in size. Of major clinical significance in relation to osteolysis and loosening is roughening of the femoral components, which may lead to greater numbers of the sub-micron-sized particles.

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Hebner, Tayler S., and Melissa A. Maurer-Jones. "Characterizing microplastic size and morphology of photodegraded polymers placed in simulated moving water conditions." Environmental Science: Processes & Impacts 22, no. 2 (2020): 398–407. http://dx.doi.org/10.1039/c9em00475k.

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Lynch, Elliot M., and Joshua B. Lovell. "Eccentric debris disc morphologies – I. Exploring the origin of apocentre and pericentre glows in face-on debris discs." Monthly Notices of the Royal Astronomical Society 510, no. 2 (December 8, 2021): 2538–51. http://dx.doi.org/10.1093/mnras/stab3566.

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ABSTRACT The location of surface brightness maxima (e.g. apocentre and pericentre glow) in eccentric debris discs are often used to infer the underlying orbits of the dust and planetesimals that comprise the disc. However, there is a misconception that eccentric discs have higher surface densities at apocentre and thus necessarily exhibit apocentre glow at long wavelengths. This arises from the expectation that the slower velocities at apocentre lead to a ‘pile up’ of dust, which fails to account for the greater area over which dust is spread at apocentre. Instead we show with theory and by modelling three different regimes that the morphology and surface brightness distributions of face-on debris discs are strongly dependent on their eccentricity profile (i.e. whether this is constant, rising, or falling with distance). We demonstrate that at shorter wavelengths the classical pericentre glow effect remains true, whereas at longer wavelengths discs can either demonstrate apocentre glow or pericentre glow. We additionally show that at long wavelengths the same disc morphology can produce either apocentre glow or pericentre glow depending on the observational resolution. Finally, we show that the classical approach of interpreting eccentric debris discs using line densities is only valid under an extremely limited set of circumstances, which are unlikely to be met as debris disc observations become increasingly better resolved.

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Lal, Basant, and Abhijit Dey. "Influence of Load and Speed on Tribological Performance of A390 and A515 Alloys in Dry Sliding Behavior A Comparative Study." International Journal of Surface Engineering and Interdisciplinary Materials Science 10, no. 1 (January 1, 2022): 1–19. http://dx.doi.org/10.4018/ijseims.310513.

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In this study, tribological characteristics and wear debris morphology of A390 and A515 alloys are evaluated and compared. Components with a high wear resistance slide are typically made with alloys are A390 and A515, while components with high hardness requirements are usually made up with SS410. Those alloys were used in brake pads, and SS410 steel is used for the brake disc. Speed and pad force are the two factors that affect tribological characteristics such as friction coefficient and wear rate. Wear debris and wear track were examined by scanning election microscopy and optical microscope, respectively. The effect of sliding speed variations on wear and friction coefficient at various load conditions was also evaluated, and a comparative analysis was reported based on wear rates, coefficient of friction, and debris morphology for both materials. The A515 alloys shows higher friction coefficient under all the process conditions except at very low loads and high speeds due to increased superficial hardness and the composition of the case layer (oxygen-diffused/oxide formed).

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Charee, Wisan, and Viboon Tangwarodomnukun. "Surface Morphology of Silicon Induced by Laser Ablation in Flowing Water." Materials Science Forum 861 (July 2016): 115–20. http://dx.doi.org/10.4028/www.scientific.net/msf.861.115.

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Underwater laser machining process has a high potential over the typical laser ablation to remove materials with less thermal damage occurring along the cut. However, the formations of vapor bubble and cut debris in water can substantially disturb the incident laser beam, thereby reducing the ablation performance. Instead of performing the ablation in still water, the flowing water technique was applied to flush away the cut debris and bubble generated. In this study, the effects of laser pulse energy, traverse speed and water flow rate on the cut surface roughness and heat-affected zone in the laser grooving of silicon were experimentally investigated and analyzed. The findings revealed that the cut surface roughness decreased with the increases in laser pulse energy and laser traverse speed. Though a higher water flow rate resulted in a rougher cut surface, the heat-affected zone can be minimized when the increased flow rate was applied.

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Palermo, Michele, Simone Pagliara, and Deep Roy. "Effect of debris accumulation on scour evolution at bridge pier in bank proximity." Journal of Hydrology and Hydromechanics 69, no. 1 (January 26, 2021): 108–18. http://dx.doi.org/10.2478/johh-2020-0041.

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Abstract Large debris transported by flood affects scour features at bridge piers and increases the risks of structural failure. Geometric characteristics of the debris and the relative position of the pier with respect to the river bank are important parameters for the scour process. The interaction between the water flow and debris accumulation increases the shear stress, turbulence and consequently enhances the scour depth at the pier. This paper aims at analyzing such effects on scour evolution at bridge piers. To this end, two series of tests were carried out under clear water condition with different debris geometries and percentage blockage ratios. Experimental evidences showed that the pier position only influences scour evolution and equilibrium morphology for low water depths. Conversely, its effect becomes negligible for scour at bridge piers with debris accumulation and higher water depths. Useful practical relationships have been derived, with satisfactory prediction capability of the scour evolution for all the tested configurations.

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Journal articles on the topic 'Debris morphology'

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