Types Of Erosion Research Articles

Arc Erosion and Morphological Characters of Ag/LSCO(12) Contacts by Different Methods

To diagnose the arc erosion type and improve arc erosion resistance of Ag/LSCO (Ag/La0.5Sr0.5CoO3-δ) contacts, making and breaking experiments were carried on Ag/LSCO(12) contacts prepared by both traditional powder metallurgy method and a modified one in this work. Arc erosion and morphological characters of this two kinds of Ag/LSCO(12) samples were investigated and the erosion mechanisms were also discussed. The results are that seven types of arc erosion morphologies of Ag/LSCO(12) contacts were classified as the lump region, the cauliflower region, the framework structure, holes and cavities, cracks, spongy region and the vestiges of fusant spreading. There are intrinsic links between these morphological characters. The spongy regions and vestiges of fusant spreading on the contact surface of Ag/LSCO(12) prepared by the new method indicates that its resistance to arc erosion is superior to the contacts prepared by traditional method.

Using 137Cs and 210Pbex measurements and conventional surveys to investigate the relative contributions of interrill/rill and gully erosion to soil loss from a small cultivated catchment in Sicily

In many cultivated areas in semiarid Mediterranean regions, soil erosion is responsible for problems related to both on-site and off-site impacts, including reduced crop productivity, water quality, and degradation of freshwater ecosystems. In some areas of Sicily, where intense short duration rainfall events are common, soil erosion is a very serious problem, especially on land subjected to continuous tillage operations. The rates of soil loss in these areas and their impact differ according to the dominant type of erosion. Several existing studies have focused on the impacts of either linear (gully- or ephemeral gully-erosion) or interrill–rill erosion, but to date the relative magnitude of these two different types of erosion, has rarely been assessed. This paper reports the results of a study aimed at comparing the relative contribution of interrill–rill erosion and gully erosion to soil loss from a small cultivated catchment located in Sicily (Italy). Surveys of ephemeral gullies (EG) in the study catchment carried out at the event scale since 1999 are used to quantify soil loss attributable to EG erosion. 137Cs and 210Pbex measurements are used to quantify the net soil loss from the catchment attributable to interrill–rill (IRR) erosion. The study demonstrates that EG formation occurred 7 years out of 10, with a mean soil loss averaged over a 10-year period equal to 26.5tha−1yr−1. The rates of IRR erosion estimated using 137Cs and 210Pbex measurements provided values of mean annual net soil loss of 38.8tha−1yr−1 and 34.2tha−1yr−1, respectively. The resulting ratios of soil loss attributable to EG to total soil loss (IRR+EG) were 0.41 and 0.44 for the 137Cs and 210Pbex measurements, respectively. The results suggest that the contributions of EG and IRR erosion are of a similar magnitude in semiarid regions of Sicily, although the precise value of the ratio is likely to vary both spatially and temporally in response to catchment morphology, soil erodibility and land use and inter-annual variability of rainfall magnitude and erosivity. The findings are consistent with those of other studies that have attempted to compare the relative efficacy of the two erosion types. The use of 137Cs and 210Pbex measurements in the study area provided important insights into the relative importance of IRR and EG erosion and the same approach could be employed in other locations where both forms of erosion occur and there is a need to quantify their relative importance.

Hydro-mechanical analysis of piping erosion based on similarity criterion at micro-level by PFC3D

Internal erosion in river levees and landslide dams has often caused serious damage of the embankment body. As one type of internal erosion, piping erosion is the process in which fine soil particles are detached from the particle skeleton of coarser particles. At microscopic scale, particle composition and migration are the two main issues of piping erosion, which are usually studied by physical model testing and numerical simulation based on continuum mechanics. In this paper, the similarity criteria of internal erosion model testing were firstly derived and then verified by particle flow code (PFC3D). The derived similarity criteria are critical to reproduce the prototype physical model through a numerical model. Secondly, a laboratory test of piping erosion was conducted, and a micro-level particle model based on the similarity criteria was developed to describe the process of piping erosion. This numerical model was developed using the discrete approach-based PFC3D, overcoming the limitations of the commonly used continuum approach. Our laboratory test clearly showed the initiation, development and failure process of piping erosion at microscopic particle level. Our numerical simulations showed very similar trend of these processes as in the laboratory tests, indicating that the PFC3D model (based on the developed similarity criteria) could accurately reproduce the processes of piping erosion. With the similarity criteria developed and strong numerical model capability verified through the laboratory tests, we believe that the discrete approach-based numerical simulation method can be used for piping erosion independently of laboratory tests.

A review on rill erosion process and its influencing factors

Rills are frequently observed on slope farmlands and rill erosion significantly contributes to sediment yields. This paper focuses on reviewing the various factors affecting rill erosion processes and the threshold conditions of rill initiation. Six factors, including rainfall, runoff, soil, topography, vegetation and tillage system, are discussed. Rill initiation and network are explored. Runoff erosivity and soil erodibility are recognized as two direct factors affecting rill erosion and other types of factors may have indirect influences on rill erosion through increasing or decreasing the effects of the direct factors. Certain conditions are necessary for rill initiation and the critical conditions are different with different factors. Future studies should be focused on 1) the dynamic changes of rill networks; 2) the combined effect of multiple factors; and 3) the relationships of threshold values with other related factors.

The impact of biomass co-combustion on the erosion of boiler convection surfaces

The erosive wear of boiler tubes caused by fly ash in coal combustion flue gases has been studied for a long time. However, there are practically no data concerning the intensity of the erosion of the heating surfaces of boilers fired with both coal and biomass, and thus it is difficult to design these particular areas appropriately.The essential problem is the tendency of the fly ash from biomass combustion to produce ash deposits on the boiler convection surfaces and to cause slagging on the radiant surfaces. In such cases, both an increase in the deposits and a shortening of the time over which the ash fouling accumulates to the maximum level are observed. Consequently, if the boiler is fitted with steam or air blowers, they are started more frequently; if not, they have to be installed. The research conducted here proves that the situation leads to serious damage to the tubes, which results from the erosion caused by ash particles carried by the blowing agent jet.The authors of this paper attempt to make a quantitative evaluation of the impact of co-firing two types of biomass (coniferous wood chips and willow wood chips) on both types of tube erosion.

Caracterización de la erosión en áreas acarcavadas en la Fm. Tudela (Bardenas Reales, Navarra)

At Bardenas Reales, erosion processes are due to hydric action and wind erosion. Climate, lithology and geomorphology are the main factors that control water erosion. Besides sediment yield by water, other forms exist to export material: mudslides and armoured mud balls. Clay material at high slopes and high dispersion index together with climate determine the presence of one type of erosion or another. On winter times, mudslides are developed while on summer high intensity storms provoke incision. Meanwhile armoured mud balls could coexist with both of them.

AB0997 When is hand osteoarthritis erosive? demographic and radiographic features

BackgroundIncreasing clinical and scientific interest has recently been raised on hand osteoarthritis (HOA); a peculiar subgroup of patients experiment more severe symptoms and characteristic structural damage in the joints (central...

Dinámica erosiva del "piping" : un ejemplo en la Depresión del Ebro

In the Bardenas regíon we recognize some hydric erosion processes, as follows: sheet-wash and runof/' rilling, badlanding and forming of gullies with Vand U section". This last type is relationed with certain piping forms, that indicate the importance of the subsurface eros ion at these points. We propose a classification for those forms, and an erosional cycle ofpiping. The anthropic inciden ce of this erosion type in the area is also considered.

Beach morphodynamics and types of foredune erosion generated by storms along the Emilia-Romagna coastline, Italy

The objectives of this study are to examine the response of a dune and beach system on the Adriatic coastline in northern Italy to the arrival of storms, compare it with seasonal (months) and medium-term (3-year) morphodynamic change, and evaluate results predicted by the numerical model XBeach. The studied coastline stretches 4km from the Bevano River mouth to the north of the site to the township of Lido di Classe to the south, where the beach is protected by coastal structures. Fieldwork consisted of topographic profile surveys using RTK-DGPS technology (7 times over an approx. 3-year period). 103 samples of surface sediment were collected along 20 of the cross-shore profiles at 6 distinct cross-shore positions, selected on the basis of morphological beach characteristics. Data analyses of dune and beach slopes enabled the study area to be divided into 6 separate morphological zones using the spatial (longshore and cross-shore) variation of morphologies located on the backshore and intertidal beach observed in a preliminary survey of the area. Other criteria were a spatial consistency in beach slopes and/or presence/absence of intertidal morphologies identified in the aerial photographs and Lidar data. The swash zone slope did not show any significant variability for the entire area. A weak seasonal trend in the variability of the mean foredune slope was observed, with steeper slopes typically during winter and flatter slopes during summer. Analysis of grain size revealed that the beach sediment is well-sorted fine sand tending to medium, with a decreasing trend in size from the Bevano River mouth southwards towards Lido di Classe. According to the Masselink and Short (1993) classification, the natural part of the study site has an Intermediate Barred Beach (IBB) and following the Short (1999) classification, results in a modally LBT (longshore bar-trough) or LTT (low tide terrace) with a small section being TBR (transverse bar and rip). Storms are considered the main factor controlling changes in the beach and dune slope. The most significant storm was recorded in March 2010 with a peak significant wave height of 3.91m. Contrary to the seasonal dune trend, several foredune slopes were observed to flatten following this event, which can be attributed to the action of dune slumping from the already weakened dune state. Modelling of foredune erosion, using a process-based model (XBeach), reproduced the erosion of the upper beach and dune toe reasonably well, but is currently limited by the acceptable slope value for dune stability, which does not account for biotic factors (e.g. plant roots). The comparison between the storm impact categories of Sallenger (2000) and the DSF (Dune Stability Factor) of Armaroli et al. (2012) shows a very good correspondence between the effects of the winter 2008–2009 storms and the vulnerability of the dune system predicted using both classifications.

Experimental study on the development of collapse of overhanging layers of gully in Yuanmou Valley, China

The collapse of overhanging layers of the heads and sidewalls of gullies accelerates gully development . Thus, the development features of the collapse of overhanging layers must be understood. In this study , the process of collapse of overhanging layers in man-made soil bodies containing different soil layers was investigated by flow scouring experiments. A soil body composed of a lower sandy layer and an upper layer of clay soil was evaluated, and a field soil profile was modelled in a test tank with an open side. The results revealed that the occurrence of the collapse of overhanging layers could be attributed to the development of a scour hole in the open side; the greater the flow rate, the lower the proportion of on -wall runoff. On -wall runoff played a more important role in the development of scour holes than off-wall runoff. The shape of scour holes formed under different flow conditions was similar. Also, the scour hole is not apparently related to the flow rate, implicating that the collapse is more dependent on rainfall (runoff) time rather than rainfall (runoff) intensity in the studied region; this is substantially different from other soil erosion types that are closely related to rainfall intensity. Moreover, the maximum length (S-L) and height (S-H) of the scour holes increased gradually with accumulated flow and scouring time; in addition, the height of the hanging soil body (H-D) gradually decreased, and a linear relationship between SL and HD was observed (H-D = -0.359; S-L + 117.3; R-2 =0.861; P = 0.003). After the seventh scour test, the scour hole triggered the collapse of the upper clay layer. The cantilever model was modified to predict the stability of the overhanging soil body. It provided a satisfactory explanation of the static balance of the weight of the soil as well as the tensile strength. After the seventh scour test, the measured and predicted threshold values of H-D, S-L, and T-C were nearly equal, and a stable balance state was attained. However, when a 10 cm tension crack appeared in the overhanging soil body, a stable balance state was obtained during the sixth scour test. (C) 2013 Elsevier B.V. All rights reserved.

Understanding marine eutrophication from agricultural runoff in semi enclosed areas: a short review in the Gulf of Geras, Greece

The understanding of marine eutrophication in semi enclosed areas due to agricultural runoff, assumes a more integrated approach taking into account the agricultural watershed, seasonal patterns of soil nutrients, rates of erosion and vegetation types. In the present case study in the Gulf of Geras, Lesvos, Greece, the transport of dissolved and solid phase nutrients of terrestrial origin to the marine environment was studied in detail using mathematical modelling. Fifteen criteria describing environmental and socioeconomic aspects were analysed using multi criteria choice methods and a number of scenarios were evaluated. Parallel to that an eutrophication model was used to describe the problem of eutrophication in the marine environment and also to assess the environmental impact from the proposed scenarios. The emphasis was placed in the interconnection between Mediterranean type ecosystem and marine coastal eutrophication. The results showed that the coupling of multi criteria analysis together with simulation modelling, provide a powerful tool for integrated coastal management practices and assessing eutrophic trends in semi enclosed areas.

Prediction of offshore bar-shape parameters resulted by cross-shore sediment transport using neural network

In order to understand the features of coastal zone and to utilize the coastal areas, it is necessary to determine the sediment movement and the resulting transport. Waves, topographic features, and material properties are known as the most important factors affecting the sediment movement and coastal profiles. In this study, by taking into consideration of wave height and period (H0, T), bed slope (m) and sediment diameter (d50), cross-shore sediment movement was studied in a physical model and various bar-shape parameters of the resultant erosion type profile were determined. Using 80 experimental data which are obtained from physical model studies, a neural network (NN) has been calibrated to predict bar-shape parameters of beach profiles. A sensitivity analysis was firstly carried out to decide data of training and test sets. Four different models, in which the rates of their training and testing set data were 80% and 20%, 70% and 30%, 60% and 40%, 50% and 50% were constituted and their performances were compared. It was determined that the model, in which the rate of its training and testing set data was 80% and 20%, respectively, has the best results. Therefore, a total of 64 experimental data were used as training set and the remainders of the experimental data were used as a testing set for the model. The performance of the NN model was compared with the regression equations developed in a previous study and the equations cited in literature indicating better performance over the equations.

Shadow photometric method for measurements of electron density in erosion plasma

The purpose of this work is property investigation of quasi-stationary plasma formations with high energy content for practical applications in high thermal physics and diagnostic of materials under extreme conditions. Investigated plasma formations are the result of two plasma counter-flows interaction process which is based on high-current discharges of plasma accelerators of erosion type in vacuum. Shadowgraphs of colliding plasma flows were made using knife and slit method. As a light source a specially made argon flash lamp was used. Averaged electron concentration in the interaction area was calculated from intensity distribution of shadowgraphs. In order to perform a correct shadow display a light filter system with transmission peak at 547nm was mounted in front of the CCD-camera. At this wavelength the relative intensity in plasma spectrum was low while in argon lamp spectrum it was near-maximum.

Overview of erosion–deposition diagnostic tools for the ITER-Like Wall in the JET tokamak

This paper presents scientific and technical issues related to the development of erosion–deposition diagnostic tools for JET operated with the ITER-Like Wall: beryllium and tungsten marker tiles and several types of wall probes installed in the main chamber and in the divertor. Markers tiles are the standard limiter and divertor components additionally coated first with a thin sandwich of Ni–Be and Mo–W for, beryllium and tungsten markers, respectively. Both types of markers are embedded in regular arrays of limiter and divertor tiles. Coated W–Be probes are also inserted in the Be-covered Inconel cladding tiles on the central column. Other types of erosion–deposition diagnostic tools are: rotating collectors, deposition traps, louver clips, quartz microbalance and mirrors for the First Mirror Test at JET for ITER. The specific role of these tools is discussed in detail.

Estimation Model of Soil Freeze‐Thaw Erosion in Silingco Watershed Wetland of Northern Tibet

The freeze-thaw (FT) erosion is a type of soil erosion like water erosion and wind erosion. Limited by many factors, the grading evaluation of soil FT erosion quantities is not well studied. Based on the comprehensive analysis of the evaluation indices of soil FT erosion, we for the first time utilized the sensitivity of microwave remote sensing technology to soil moisture for identification of FT state. We established an estimation model suitable to evaluate the soil FT erosion quantity in Silingco watershed wetland of Northern Tibet using weighted summation method of six impact factors including the annual FT cycle days, average diurnal FT phase-changed water content, average annual precipitation, slope, aspect, and vegetation coverage. Finally, with the support of GIS, we classified soil FT erosion quantity in Silingco watershed wetland. The results showed that soil FT erosion are distributed in broad areas of Silingco watershed wetland. Different soil FT erosions with different intensities have evidently different spatial and geographical distributions.

Application of Gully and Rill Erosion Indicators for Estimating Soil Loss Using GIS Techniques

The problems of land degradation and soil loss are among the major problems of watersheds in Iran. For erosion andsediment estimation one can use statistical and empirical methods. For doing this, land unit map and the map of effectivefactors should be prepared. For erosion and sediment estimation one can use statistical and empirical methods. However,these empirical methods are usually time consuming and do not give accurate estimation of erosion. In this study, weapplied GIS techniques to estimate erosion and sediment of Menderjan Watershed at upstream of Zayandehrud River incentral part of Iran. Erosion features of each land unit were defined on the basis of land use, geology and land unit mapsusing GIS. The UTM coordinates of each erosion type with higher erosion intensities such as rills and gullies wereinserted in GIS using GPS data. The frequency of erosion indicators of each land unit, land use and sediment yield ofthese indices were calculated. Also by using sediment yield changes in watershed outlet (hydrometric station), theeffective parameters in sediment production were identified. The results of this study can be used for more rapid and moreaccurate estimation of erosion than traditional methods. These results can also be used for regional erosion assessment andcan be applied by using remotely- sensed data.

Experimental Investigation of the Effects of Suffusion on Physical and Geomechanic Characteristics of Sandy Soils

Abstract This paper reports the measured effects of suffusion, a type of internal erosion, on the physical and geo-mechanical properties of soils including permeability, volume change, compressive strength, and soil grains gradation. A poorly graded river sand with the addition of 10 % kaolinite clay was used to create three gap-graded soils and an unaltered poorly graded “original soil.” Testing was performed using a modified triaxial apparatus that permits seepage through compacted specimens and allows collection of effluent and eroded soils. The specimens, 5.1 cm in diameter and 10.2 cm in length, were monitored for changes in volume and permeability during the suffusion tests. After erosion, the specimens were compressed using the consolidated-undrained (CU) test. The collected effluent samples were dried to determine the erosion rate and eroded soil particle gradations with respect to effluent volume. Companion control specimens were tested without erosion. The results revealed that suffusion may affect some physical and geo-mechanical properties of soils. Permeability reduction was generally observed in all soils, indicating fine grains migration and clogging within the specimens. The three gap-graded soils each exhibited a greater degree of internal erosion (suffusion), permeability reduction, and volume change than the original soil. The experimental setup and testing protocol also provided a feasible methodology for further research on the effects of suffusion on the physical and geo-mechanical properties of soils. Limitations of this research and future research recommendations on this topic are provided at the end of this paper.

Essential Type of Bank Collapses in the Middle-Lower Yangtze River and Corresponding Preventive Measures

Four types of bank collapses in the middle-lower Yangtze River, that is erosion type, crash type, slippage type and flow-slide type, are pointed out, and characteristics and formation conditions of each one are analyzed. In order to provide a reference for decision-making of calamity reduction and improvement project, some preventive measures on them, including monitoring of river hydrology, morphology near bank, and hydrologicalgeology, and inspection and investigation of outward indication of bank and human activity, are presented by means of analysis on above-mentioned aspects.

Treatment of severe cuff tear arthropathy with the humeral head resurfacing arthroplasty: two-year minimum follow-up

The aim of the study was to evaluate the outcome of a humeral head resurfacing arthroplasty implanted toward valgus for patients with cuff tear arthropathy (CTA). We monitored 24 patients with CTA who underwent resurfacing arthroplasty. Patients were assessed with use of the Constant score and a subjective satisfaction score. The rotator cuff was evaluated preoperatively by magnetic resonance imaging. The Sirveaux classification of glenoid erosion in glenohumeral osteoarthritis with massive rupture of the cuff was used to grade the preoperative status of the glenoid. The mean absolute Constant score for the entire cohort improved from 21 points (range, 7-44 points) to 63 points (range, 23-89 points) at a mean of 38 months (range, 24-56 months). Patients with an intact or moderately atrophied teres minor muscle (n = 16) showed a significantly better Constant score (P = .011) and greater active external rotation (P = .034) than patients with severe atrophy. Neither the type of glenoid erosion according to Sirveaux nor the inclination angle of the implant has an effect on the clinical or functional outcome. For selected patients with CTA, resurfacing arthroplasty of the humeral head provides satisfactory medium-term outcomes. The teres minor muscle is necessary for maintaining or establishing external rotation. In patients with massive limitation of motion and total absence of the subscapularis tendon, the implantation of a humeral surface replacement should be seriously considered.

Comparison slide zones by Nilsen method with active tectonic zones produce of Smf index

Slide zones under title erosion types related to more active tectonic factors for example stream length-gradient (Sl),ratio of valley-floor width to valley height (Vf), drainage basin shape (Bs), mountain front sinuosity (Smf), drainage basin asymmetry (Af) and hypsometric integral (Hi). This research is noticeable comparison produce slide zones by Nilsen. The active tectonic zones produce from Smf index under title one of the important active tectonic factors. Determination landform of geometry or morphometry factors is the one of best method for study and evaluation active tectonic. The first provided Dem maps in GIS software by topography, geology, tectonic maps participant with field activities. Then provided active tectonic map by Smf index into three class A, B, C and landslide hazard zonation map into five class stable zone, generally stable zone, stable moderately stable zone, moderately un-stable zone and talented to liquefaction zone. Comparison and conformity landslide hazard zonation map with hazard zonation into Smf index showed about percent 71(51120 hectare) moderately unstable zone and talented for liquefaction zone settled in A zone Smf map and percent 29 (20880 hectare) remained settled sequential percent 18 (12960 hectare) and percent 11 (7920 hectare) in B, C zone of hazard zonation active tectonic produce from Smf index. In other word in research showed relationship landslide zones produce landslide hazard zonation by Nilsen to active tectonic zones by Smf index in the study region.