نتایج جستجو برای: erosion

تعداد نتایج: 30410  

2012
Jin-Keun Choi Arvind Jayaprakash Georges L. Chahine

A simple mathematical expression is presented to describe cavitation mean depth of erosion versus time for cavitating jets and ultrasonic cavitation. Following normalization with a characteristic time, t*, which occurs at 75% of the time of maximum rate of erosion, and a corresponding material characteristic mean erosion depth, h*, the normalized erosion depth is related to the normalized time ...

2010
F. Bisschop P. J. Visser C. van Rhee H. J. Verhagen

Convential models for the erosion of non-cohesive sediments overestimate the erosion rate induced by high flow velocities. These high flow velocities occur, for instance, in breaching of embankments or dunes (flow velocities up to 10 m/s) or in jetting sand with a trailing suction hopper dredger (30 to 60 m/s). At these very large flow velocities the erosion process is significantly influenced ...

2010
CH Chu Karie KL Pang Edward CM Lo

OBJECTIVES To study the dietary behavior and knowledge about dental erosion and self-reported symptoms that can be related to dental erosion among Chinese adults in Hong Kong. METHODS Chinese adults aged 25-45 years were randomly selected from a list of registered telephone numbers generated by computer. A telephone survey was administered to obtain information on demographic characteristics,...

2005
M. S. ElTobgy E. Ng M. A. Elbestawi

Material damage caused by the attack of particles entrained in a fluid system impacting a surface at high speed is called ‘Erosion’. Erosion is a phenomenon that takes place in several engineering applications. It also can be used in several manufacturing process such as abrasive waterjet machining. Erosion is a complex process dependent on particle speed, size, angle of attack as well as the b...

2016
Shiva P. Pudasaini

Erosion, entrainment and deposition are complex and dominant, but yet poorly understood, mechanical processes in geophysical mass flows. Here, we propose a novel, process-based, two-phase, erosiondeposition model capable of adequately describing these complex phenomena commonly observed in landslides, avalanches, debris flows and bedload transport. The model is based on the jump in the momentum...

Journal: :Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology 2011
Alison Maresh Olga F Martins Jonathan D Victor Samuel H Selesnick

OBJECTIVE To describe and quantify growth patterns of cholesteatomas within the middle ear using a scaled rating system that characterizes patterns of ossicular erosion. STUDY DESIGN Retrospective case review. SETTING Tertiary referral center. PATIENTS Patients undergoing first-time surgery for primary and secondary acquired cholesteatomas. INTERVENTIONS Intraoperative assessments of os...

Journal: :مدیریت خاک و تولید پایدار 0
حیدر غفاری دانشگاه تهران منوچهر گرجی دانشگاه تهران

maintaining soil productivity is one of the key factors in sustainable agriculture. soil erosion reduces soil productivity over a long-term period of time. therefore, determining soil erosion tolerance is necessary for sustainable agriculture production. in this study, the long-term effects of erosion on soil productivity in the typical kohin watershed were evaluated. the soil productivity inde...

Journal: :European journal of oral sciences 1996
J M ten Cate T Imfeld

Although reports on dental erosion have always appeared in the dental literature, there is currently a growing interest among researchers and clinicians. Potential risk factors for dental erosion are changed lifestyle and eating patterns, with increased consumption of acidic foods and beverages. Various gastrointestinal and eating disorders expose the dentition to frequent contacts with very ac...

Journal: :Australian dental journal 2010
S Taji W K Seow

Dental erosion is increasingly recognized as a common condition in paediatric dentistry with complications of tooth sensitivity, altered aesthetics and loss of occlusal vertical dimension. The prevalence of erosion in children has been reported to range from 10% to over 80%. The primary dentition is thought to be more susceptible to erosion compared to the permanent dentition due to the thinner...

2005
Peter R. Robichaud

The increasing size and severity of wildfires in the western United States has caused a corresponding increase in post-fire emergency erosion control activities. Hillslope treatments, such as broadcast seeding, mulching and installed barriers, are applied to reduce runoff and erosion, as well as downslope sedimentation. However, there are few data to determine if these post-fire treatments are ...

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