Erosion Progress Research Articles

ОСОБЛИВОСТІ УРАЖЕННЯ ШЛУНКА В ЛАБОРАТОРНИХ БІЛИХ ЩУРІВ, ВИКЛИКАНИХ РІЗНИМИ РЕЖИМАМИ СТРЕСОВОЇ НАПРУГИ

Резюме. Будь-який стрес провокує ураження слизової оболонки в шлунку щурів. При хронічному стресі, викликаному тривалою гіпокінезією, гострий стрес викликає важкі ураження з ерозією і прогресом виразки у всіх щурів тільки при тривалій іммобілізації (3 годин). Різні умови тривалого іммобілізаційного стресу провокують виникнення гастритів, ерозій, виразок, що відзначаються більше при повсякденній іммобілізації тварин.

Does erosion progress differently on teeth already presenting clinical signs of erosive tooth wear than on sound teeth? An in vitro pilot trial

BackgroundErosive tooth wear (ETW) is clinically characterized by a loss of tooth surface, and different enamel depths may have different susceptibility to demineralization. Therefore, the aim of this in vitro pilot study was to assess if the progression of erosive demineralization is faster on teeth already presenting signs of ETW when compared to originally sound teeth.MethodsWe selected 23 central incisors: 14 were clinically sound (Sound) and 9 presented clinical signs of early erosive tooth wear (ETW-teeth). The teeth were embedded in resin, leaving an uncovered window of native enamel (6.69 ± 2.30 mm2) on the incisal half of the labial surface. We measured enamel surface reflection intensity (SRI) initially and after each consecutive erosive challenge (1 % citric acid, total of 4, 8, 12, 16, 20 and 24 min). Calcium released to the citric acid was measured with an atomic absorption spectrometer.ResultsWe observed higher initial SRI values in ETW-teeth than in Sound teeth (p = 0.007). During in vitro erosive demineralization, we observed that erosion on originally Sound teeth progressed significantly slower (p = 0.033) than on ETW-teeth: SRI decreased by 75 % (from 100 to 25 %) on Sound teeth, and by 89 % (from 100 to 11 %) on ETW-teeth. Calcium release increased during erosion, but presented no significant differences (p = 0.643) between originally Sound (0.031 μmol/mm2) and ETW-teeth (0.032 μmol/mm2). There was satisfactory correlation between calcium release and rSRI values (rs = −0.66).ConclusionThe optical reflectometer distinguished originally sound teeth from those with signs of ETW, and the results suggest that acid demineralization progresses differently on teeth already presenting clinical signs of ETW than on sound teeth.

Surface erosion behavior of an intrusive probe in pipe flow

Unconsolidated sandstone reservoirs in northwestern China exhibit high sand production rates. This extreme working condition causes unusual erosion behaviors of ER (electrical resistance) probes. To describe the erosion behavior of an ER probe in this extreme condition, an intrusive probe is mounted in a pipeline in the same manner as an ER probe. The sand production rates are adjusted to simulate the working conditions of an unconsolidated sandstone gas field. Factors, including the evolution of the surface profile, unstable sand production rate and probe materials, are studied for erosion behaviors. The results show that the peak values of the sand production rate substantially affect the erosion progress. Different wear mechanisms were discovered for different materials. Under a 250-kg sand load, the most seriously eroded upstream surface was the top of the probe at the beginning of the erosion test, but the erosion surface shifted to the bottom of the probe by the end of the experiment. The erosion angle α of the upstream surface is decided by the upstream edge angle θ. A model, modified to account for the evolution of the surface profile, is suggested and validated using experimental data, and the model had an average relative deviation of 9.9% for a 330-kg erosion and 12.6% for a 480-kg erosion. The limitations and applicable range of the modified model are listed. This study offers a numerical model for the research and development of a strong, flexible ER probe to be used for higher sand production rates.

Real-time in situ monitoring of poly(lactide-co-glycolide) coating of coronary stents using electrochemical impedance spectroscopy.

Monitoring erosion progress of biodegradable drug carrying polymer coated on coronary drug eluting stents (DES) is largely hindered because of the small amount of coating material as well as the irregular profile of coating, both of which make the monitoring using traditional methods highly challenging. In our study, electrochemical impedance spectroscopy (EIS), a widely used method in the study of metal corrosion, was used to address the challenges traditional methods face. In vitro, remained mass and molecular weight drop data of film-like poly(lactide-co-glycolide) (PLGA) samples due to degradation were monitored using traditional mass loss measurement and size exclusion chromatography (SEC) methods. The obtained data were compared to the changes of capacitance and impedance measured by EIS from PLGA-coated stainless slices with an equivalent electrical circuit model. The results showed that the changes of the resistance and capacitance obtained by EIS, which indicates transformations of PLGA coating, can be correlated to the degradation measured by traditional methods, such as SEC. Furthermore, EIS method was applied to monitor and evaluate the erosion progress of a real stent with PLGA coating. Our results suggested that EIS method can accurately monitor real-time erosion process of thin polymer coatings on DES in situ.

Humeral surface replacement for osteoarthritis

Background and purpose Humeral resurfacing has shown promising results for osteoarthritis, but revisions for glenoid erosion have been reported frequently. We investigated the hypothesis that preoperative glenoid wear and postoperative progress of glenoid erosion would influence the clinical outcome.Methods We reviewed 61 resurfacing hemiarthroplasties (55 patients) for primary osteoarthritis. 6 patients were lost to follow-up and 5 had undergone revision arthroplasty. This left 50 shoulders in 44 patients (mean age 66 years) that were followed for mean 30 (12–44) months. Complications, revisions, and the age- and sex-related Constant score were assessed. Radiographs were evaluated for loosening and glenoid erosion according to Walch.Results Of the 50 shoulders that were functionally assessed, the average age- and sex-related Constant score was 73%. In patients with preoperative type-B2 glenoids, at 49% it was lower than in type-A1 glenoids (81%, p = 0.03) and in type-B1 glenoids (84%, p = 0.02). The average age- and sex-related Constant score for patients with type-A2 glenoids (60%) was lower than for type-A1 and -B1 glenoids and higher than for type-B2 glenoids, but the differences were not statistically significant. In the total population of 61 shoulders, the radiographs showed postoperative glenoid erosion in 38 cases and no humeral prosthetic loosening. Revision arthroplasty was performed in 11 cases after 28 (7–69) months. The implant size had no statistically significant influence on the functional outcome. The size was considered to be adequate in 28 of the 50 functionally assessed shoulders. In 21 cases, the implant size was too large and in 1 case it was too small.Interpretation We found frequent postoperative glenoid erosion and a high rate of revision arthroplasty after humeral resurfacing for primary osteoarthritis. Oversizing of the implants was common, but it had no statistically significant influence on the functional outcome. Inferior results were found in the presence of increased eccentric preoperative glenoid wear. Total shoulder arthroplasty should be considered in these patients.

Landforms and landscape evolution in the Mylliem Granite Area, Meghalaya Plateau, Northeast India

The Mylliem granite is one of many igneous bodies within the basement complex of the Meghalaya Plateau, northeast India. Although relatively small in size at c. 90 km2, it is very diverse geomorphologically and shows a range of distinctive landscapes within its limits. Relict flat watershed ridges and topographic basins characterize the northern and eastern part of the pluton, whereas to the southwest the relief becomes higher, with steeper hillslopes and deeply incised valleys. Deep weathering and thick saprolites are abundant, as are residual landforms resulting from stripping of the saprolite: domes, tors and boulders. The major reason behind the diversity of granite landscape of the Mylliem pluton is the progress of headward erosion, initiated at the Dauki fault in the south of the Meghalaya. Headward erosion enhances local relief and hence, weathering systems. Multi‐concave morphology is gradually transformed into multi‐convex one, which is hypothesized to be the specific mode of plateau evolution and scarp retreat in granite bedrock.

충남 태안반도의 해안침식 실태와 양상

This study has two main purposes. First, Taean peninsula coastal area was searched to find out the changing realities and patterns of coastal landforms due to the climate change and sea level rise. As a result, of coastal areas, coastal erosion patterns show distinctively, and the type is distinguished by ① Erosion of sandy beach (coast) and sand dune, ② Backward seacliff and slope collapse, ③ Shore protection collapse. It is shown that time series observation and experiment should be added, but it seems that there is no disagreement about the progress of coastal erosion and possibility of acceleration according to previous research summary view and this study. Second, These changes in coastal terrain is concerned that it can cause huge amount of socio-economic losses and, therefore, accurate prediction and preparation for future changes are needed. With these concerns, numerous studies have attempted to find and explore the vulnerability of coastal areas, and this subject becomes big issue among changes in the coastal environment. However, studies about this subject is yet further support level, and domestic application, the needs of new model development are necessary to be examined. Therefore, in this study, four kinds of overseas case studies has been analyzed to evaluate and predict coastal environmental vulnerability, and looked at the possibility of domestic application and necessity of new model development.

Interrill and Rill Erosion on Hillslope

Interrill and rill erosion are commonly observed erosion processes to coexist on hillslope. Understanding of the interrill and rill erosion process is the key for the development of physically-based erosion prediction models. This paper reviewed the research progress of interrill and rill erosion, and the relationship between them. The shortages were also put forward. Finally, the trends for future development and questions are also discussed.

Software for detecting 3D movements: The case of olive tree displacements in an olive grove located on sloping land

The phenomenon of erosion is increasingly analyzed from different perspectives by interdisciplinary working groups attempting to implement more effective preventive measures. Numerical data are normally used to quantify the effects of erosion. This paper examines the case of an olive grove where there is clear evidence of the progress of erosion. Software is programmed to calculate the 3D field movements and also represents them graphically, allowing their integration into a GIS. This makes it possible to interrelate information from different sources stored in the database in order to perform advanced queries and make appropriate decisions to prevent risk situations.

Impact factors of soil wind erosion in the center of Taklimakan Desert

The development and progress of soil wind erosion are influenced by the factors of climate, terrain, soil and vegetation, etc. This paper, taking Tazhong region, a town in the centre of the Taklimakan Desert, as an example and using comparative and quantitative methods, discussed the effects of climate, surface roughness (including vegetation cover) and surface soil properties on soil wind erosion. The results showed that the climate factor index C of annual wind erosion is 28.3, while the maximum of C is 13.9 in summer and it is only 0.7 in winter. The value of C has a very good exponential relationship with the wind speed. In Tazhong region, the surface roughness height is relatively small with a mean of 6.32 × 10 −5 m, which is in favor of soil wind erosion. The wind erosion is further enhanced by its sandy soil types, soil par- ticle size, lacking of vegetation and low soil moisture content. The present situation of soil wind erosion is the result of concurrent effects of climate, vegetation and surface soil properties.

Coastal erosion along the west coast of the Taiwan Strait and it’s influencing factors

Based on the field surveys and repeated cross-profile observations combined with the comparison of many years’ topographic maps, this study shows the spatial variability and varying patterns of coastal erosion along the west coast of the Taiwan Strait. Regional differentiation in the Meso-Cenozoic coastal tectonics determined the irregular coastline and geological background for large-scale coastal erosion distribution. The intensity of coastal erosion on the west side of the Taiwan Strait is mild in the northern region, severe in the central region and modest in the southern region. The beaches along the coast are mainly backed by dunes, seawalls or cliffs. The dunes and beaches show periodic erosion and recovery along the coast adjacent to river mouths, while persistent retreat of frontal dunes and beaches tends to occur in other areas. The beach erosion occurs mainly in front of seawalls. Due to the low strength of the unconsolidated sediment the soft cliffs suffer the severest coastline recession. Sea level rise and river sediment discharge reduction are main causes of coastal erosion. Storm surge is common in the studied area and plays an important role in the progress of coastal erosion. Human activities including coastal constructions and sand mining also tend to interfere strongly with the balance of sediment budget in some coastal cells.

Beach Process of Artificial Beach in Ibusuki Coast and the Effect of Countermeasure Works against Coastal Erosion

Ibusuki coast has attracted many tourists by its scenic and recreational value, however, recent progress of coastal erosion has resulted in frequent wave overtopping disaster. To avoid interruption of oceanic view by shore protection works, the integrated shore protection system composed of artificial nourishment works and increase of seawall crown height were adopted. DRIM (Distorted RIpple Mat) was also applied for the first time in Japan as a permanent facility to prevent the beach nourishment sand from being washed away. The present study discusses the efficiency of the countermeasure works comprised of DRIM and a groin based on wave observations and field surveys.

Numerical modelling of aeolian erosion over rough surfaces

AbstractThe presence of non‐erodible roughness elements on erodible surfaces has the effect of absorbing part of the wind shear stress and thus protecting the erodible surface from wind erosion. This paper examines the shear stress distribution over roughness arrays of varying density, representing the progress of erosion on a bed of erodible and non‐erodible particles. Three‐dimensional numerical simulations, simulating wind flow over a bed of particles covered by roughness elements, were conducted in order to investigate the effect of roughness elements on the shear stress near the surface. The results of these simulations confirm that the erosion of soil by wind is strongly attenuated by the presence of roughness elements on the surface and depends on the geometric properties of the roughness elements. Based on the new numerical results obtained, a refinement of existing theoretical approaches is developed to describe the dependence of the friction velocity upon roughness frontal area and real exposed cover rate. The new formulation proposed will allow a more accurate evaluation of shear stress partitioning as a function of topographic changes. Copyright © 2010 John Wiley & Sons, Ltd.

VCTFK 끝단에서 발생되는 트래킹의 진전특성

This paper describes the characteristic of tracking progress happened at the end of the polyvinyl chloride insulated cabtyre oval cord(VCTFK) that is widely used for distribution cord. Tracking is occurred owing to the drop of electrolyte at the end of the VCTFK. The tracking progress and its characteristic happened at the end of the VCTFK are as follow; Carbonization and electrical erosion are happened at the end of the VCTFK. Electrical erosion is begun at the insulation layer near conductors. After that, it is also happened at the sheath layer. Accumulation of carbonized insulation and sheath materials at the end of the VCTFK is begun after progress of electrical erosion. When the accumulation is progressed arc discharge is appeared and finally it goes to tracking breakdown.

Logistic curve model of cavitation erosion progress in metallic materials

The authors previously found that the change in volume loss rate with the exposure time can be expressed by a logistic curve. In this study, the validity of this model is examined for various materials such as pure aluminum, carbon steels, stainless steels, cobalt alloys, and so on. The MDE (mean depth of erosion) d as a function of the exposure time can be expressed by three parameters α , β and c as in the following equation: d = α β t − 1 β ln 1 + c 1 + c e − α t The parameters α , β and c are derived from the relation between the nominal incubation period and the slope of the maximum rate stage, from the average thickness of the removed layer when the nominal incubation period is terminated, and from an arbitrary point ( t 0 , d 0 ) of the MDE in the maximum rate stage. We conclude that the calculated curve based on this model is in good agreement with the MDE data points for various materials, test conditions and test methods.

Characterizing cavitation erosion particles by analysis of SEM images

Wear particles produced by vibratory cavitation erosion on stationary-aluminum Al-99.999 were analyzed using scanning electron microscope (SEM), forming a database for further analysis. The particle morphology features were first clarified based on the characteristic stages of the vibratory erosion rate-time pattern. Next, size, area, perimeter and shape factors (elongation and roundness) were determined for eroded particles, using image analysis software. In incubation period, the particles have distinctive characteristics which differed from that for the subsequent periods. These characteristics include the value of longitudinal ratio and roundness factor, limit size range and morphological features such as lamella shape, folding, curving with one of the particle surfaces as the virgin surface. In acceleration, steady-state and attenuation periods, the particles have a wide size range and larger thickness compared with that for the incubation period. The maximum particle size reached about 360 μm in acceleration and steady-state period. For all the cavitation erosion rate periods, the particles were out of sphericity and they have a roundness factor larger than 2. Detailed surface characteristics of the particles produced during cavitation erosion is significant and can open ways for monitoring the cavitation erosion progress.

On fractional approach to assessment of material resistance to cavitation

Insufficient compatibility of cavitation resistance assessments based on laboratory tests conducted under different cavitation conditions is generally considered a major methodological difficulty whenever quantitative prediction of material performance under field conditions is attempted. The present paper reports a substantial progress made recently by the authors in their efforts to develop the procedure of cavitation erosion resistance assessment yielding compatible results even in case of experimental tests having been conducted at rigs of different design and principle of operation. The approach developed assumes that the material resistance to cavitation may be described satisfactorily by its response to individual fractions of cavitation pulses amplitude distribution. The backbone of the approach is a differential superposition law, which allows modelling erosion progress under polyfractional cavitation load by keeping continuous control over erosive process inputs contributed by individual fractions of cavitation pulses distribution. The model developed allows determining reference material resistance to individual load fractions basing on laboratory tests conducted under several specified cavitation conditions, determining the effective load distribution at an arbitrary rig basing on erosion tests of a set of reference materials and predicting the structural material performance in the field, provided the load distribution has been previously established. The general concept of the approach was already presented during the ICEAW conferences in 1999 and 2003. Now, numerical codes and some preliminary results are also available. Further progress requires enhancing experimental technique of cavitation pulses measurement under laboratory conditions. An action plan aimed at full validation of the method and its implementation into laboratory practice is presented in the end of the paper.

EROSION PROCESS OF COHESIVE SEDIMENT IN AN ESTUARINE CHANNEL

The erosion process of cohesive sediment in an estuarine channel was studied using thermometers. Sixteen self-logging thermometers were attached to a fishing rod at intervals of 0.1m; 15 of them were sunk in a muddy bed and one was placed in river water. The progress of bed erosion was estimated from the difference in the water and mud temperatures. This is because the water temperature, which is essentially higher than the ground temperature, drops rapidly when flood discharge occurs. The bottom shear stress was calculated by ADCP's velocity profile; bed erosion occurs when the shear stress exceeds 1.8 N/m2. The heat diffusion coefficients of the bed sediment were estimated using an equation of heat conduction. Their values suggest that the moisture content in the upper layer was greater than 200% and the lower layer comprised compacted silt.

CHARACTERIZING CAVITATION EROSION PARTICLES BY ANALYSIS OF SEM IMAGES

Detailed surface characteristics of the particles produced during cavitation erosion may well be significant in monitoring the cavitation erosion progress. Utilizing computer image analysis techniques, the size and shape factor for particles of Al-99.999 were analysed. The particle morphology features were also clarified. In incubation period, The particles have distinctive characteristics which differed from that for the subsequent periods. These characteristics include the value of longitudinal ratio and roundness factor, limit size range and morphological features such as lamella shape, folding, curving and one of the particle surfaces was the virgin surface. In acceleration, steady-rate and attenuation period, the particles have a wide size range and larger thickness compared with that for the incubation period. The maximum particle size was in acceleration and steady-rate period, and it was about 360 µm. For all the cavitation erosion rate periods, the particles were out of sphericity and they have a roundness factor larger than 2. The particle generation mechanism is fatigue failure.

Concise review of interrill erosion studies in SE Spain (Alicante and Murcia): erosion rates and progress of knowledge from the 1980s

AbstractFrom the 1980s onward studies on interrill soil erosion were intensified in SE Spain. The main achievements of the research carried out in the field areas of Alicante and Murcia concern: first, (1) the estimation of erosion rates directly in the field under a wide range of methodologies, different scales and different environmental conditions; (2) estimations based on existing models, such as the USLE, carried out for different subcatchments of the Segura and Júcar catchments; and (3) other parametric and physical event‐based models have also been calibrated and validated.Second, the progress of the knowledge in understanding erosion mechanisms. New and reviewed concepts regarding mainly hydrological behaviour and sediment movement and transport at patch, slope and catchment scale have improved our understanding of soil‐erosion processes in Mediterranean‐type ecosystems. These concepts focus on: (1) the definition of runoff generation models more appropriate to Mediterranean conditions; (2) the definition of thresholds for runoff generation; (3) the definition of models of soil water redistribution within soils and at landscape level; (4) the establishment of conditions and controls for sediment detachment and movement; and (5) the characterization of the change in the controlling factors of soil erosion and degradation under different environmental characteristics (climatic or human‐induced). The insights into soil‐erosion processes obtained and the renewed hydrological and geomorphological concepts achieved can be very valuable for the design of new strategies of erosion management and ecosystems restoration. Copyright © 2005 John Wiley & Sons, Ltd.