Litovelské Pomoraví—Landscape Around Anastomosing River Pattern of Morava

2016 ◽  
pp. 291-304 ◽  
Author(s):  
Zdeněk Máčka
Keyword(s):  
River Pattern

Application of Fractal Theory on River Bed Form

2012 ◽  
Vol 212-213 ◽  
pp. 236-240 ◽  
Author(s):  
Yin Jun Zhou ◽  
Fei Li ◽  
Li Chen ◽  
Zhong Wu Jin ◽  
Jun Wang
Keyword(s):  
Fractal Dimension ◽  
Surface Area ◽  
Fractal Theory ◽  
Irregular Boundary ◽  
Surface Fractal Dimension ◽  
Surface Fractal ◽  
River Bed ◽  
Bed Form ◽  
Fractal Characteristics ◽  
River Pattern

Fractal theory is used to describe river bed form. Based on improvements in some aspects of Surface area – Scale Method, such as, estimation of surface area, boundary treatment and so on, the calculation method of surface fractal dimension with irregular boundary is obtained, and the new method has good application on the bed surface fractal dimension calculation. The fractal characteristics of river bed surface morphology are discussed by combination with river-pattern, river regime, river process and changes of BSD. BSD can be used to study some related problems, such as analysis of river regime, distinction of river pattern, calculation of river resistance and so on.

Powder Metallurgical Processing of Ti6Al4V Alloy

2011 ◽  
Vol 217-218 ◽  
pp. 1336-1342
Author(s):  
Na Liu ◽  
Zhou Li ◽  
Hua Yuan ◽  
Wen Yong Xu ◽  
Yong Zhang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Ti6al4v Alloy ◽  
Gas Atomization ◽  
Metallurgical Processing ◽  
Transformation Structure ◽  
Powder Particles ◽  
Fracture Features ◽  
River Pattern ◽  
Brittle Cleavage Fracture ◽  
Powder Fraction

Ti6Al4V powders were produced by Argon gas atomization, the powder fraction ＜ 250μm was hot isostatically pressed (HIP) at 920°C and 140MPa. The properties of pre-alloyed powders and the compact were investigated in this paper. Powder particles are almost perfectly spherical. The microstructure of powder surface is approximate hexagonal cellular structure, the inner structure exhibits cellular αphase and needle-like martensiteα′ phase, these are resulting from the rapid solidification. After HIP, Ti6Al4V alloy has a Widmanstaten microstructure consisting of continuous grain boundary α（GBα）phase and β transformation structure, the grain size of GBα phase is in the range of 5～15μm . The tensile test at room temperature shows that strength of samples is 880MPa, the fracture surface exhibits obvious brittle cleavage fracture features including cleavage facets with river pattern and a few elongate dimples of different sizes and big voids at localized area.

Penetration Damaging Behavior of TB17 Titanium Alloy

2020 ◽  
Vol 993 ◽  
pp. 100-107
Author(s):  
Jing Li ◽  
Yun Peng Xin ◽  
Tao Jiang ◽  
Xin Nan Wang ◽  
Zhi Shou Zhu
Keyword(s):  
Titanium Alloy ◽  
Adiabatic Shear Band ◽  
Shear Bands ◽  
High Strength ◽  
Adiabatic Shear ◽  
Adiabatic Shear Bands ◽  
Internal Wall ◽  
Micro Cracks ◽  
Opening Stage ◽  
River Pattern

The damage behavior of TB17 titanium alloy with ultra-high strength was studied by 12.7mm diameter armor piercing test. The characteristics and mechanism of damaging were analyzed by the observation of damage morphology of target board. The results indicated that the area was irregular at the opening stage, the internal wall were turtle-shell-like or poly-porous, a few cracks and no adiabatic shear band was observed. The zone was parabolic at the penetrating stage, the internal wall were granular or river pattern, adiabatic shear bands and fragments existed around the crater. A large number micro-pores and micro-cracks originating from the adiabatic shear bands expanded and formed macroscopic cracks. Finally, the target board fractured.

Influence of river pattern and sediment input on estuary morphology

2020 ◽  
Author(s):  
Anne Baar ◽  
Elena Bastianon ◽  
Lisanne Braat ◽  
Daniel Parsons
Keyword(s):  
River Discharge ◽  
Large Scale ◽  
Numerical Models ◽  
Sediment Supply ◽  
Tidal Amplitude ◽  
Model Studies ◽  
Braiding Index ◽  
Sediment Input ◽  
River Pattern

<p>Alluvial estuaries are dynamic landscapes that are very sensitive to changes in boundary conditions such as river discharge and sediment supply. A better understanding of the influence of upstream river discharge and sediment input on the development of estuaries under various scenarios requires long-term morphodynamic models, to both predict future changes and improve geological interpretations by storing the stratigraphy. Past 1D model studies have shown that upstream river discharge has a significant effect on the equilibrium bed profile of estuaries, but these studies ignore the effect of 2D bar and channel formation. Using 2D numerical models to predict the development of these systems on the scale of millennia proved to be difficult, since the modelled morphology is very sensitive to the choice in e.g. sediment transport predictor and bed slope effect. In this study, we use the knowledge of previous research that determined best parameter settings for realistic river and bar patterns to model long-term and large-scale estuary morphodynamics in Delft3D. Our objective is to quantify the effects of river discharge and sediment supply on the shape of estuaries and its deposits. Firstly, we systematically varied upstream river width and tidal amplitude to examine the relation between upstream river pattern and estuary dimensions. We quantified e.g. braiding index, bar dimensions, and tidal excursion length. Results show that flood flow velocities and tidal prism are less influenced by river discharge than suggested by 1D models, and are significantly influenced by the braiding index of the river. With relatively high tides, estuary bar patterns depend on tidal amplitude, while with lower tides estuary depth and braiding index are related to upstream river width and discharge. Next steps will include varying discharge to study the effect on the rate of adaptation of the river and estuary, and varying the grain size of the sediment input at the upstream boundary. We will input coarse sediment to explore differences between fluvial deposits and tidal currents, and fine sediment to use the model for research related to biofilm.</p>

Historical changes in the distribution and functions of large wood in Puget Lowland rivers

2002 ◽  
Vol 59 (1) ◽  
pp. 66-76 ◽  
Author(s):  
Brian D Collins ◽  
David R Montgomery ◽  
Andrew D Haas
Keyword(s):  
Land Use ◽  
Field Data ◽  
Field Studies ◽  
Archival Data ◽  
Large Wood ◽  
Valley Bottom ◽  
Lowland Rivers ◽  
European Settlement ◽  
River Pattern ◽  
Channel Unit

We examined changes in wood abundance and functions in Puget Lowland rivers from the last ~150 years of land use by comparing field data from an 11-km-long protected reach of the Nisqually River with field data from the Snohomish and Stillaguamish rivers and with archival data from several Puget Lowland rivers. Current wood abundance is one to two orders of magnitude less than before European settlement in the Snohomish and Stillaguamish basins. Most importantly, wood jams are now rare because of a lack of very large wood that can function as key pieces and low rates of wood recruitment. These changes in wood abundance and size appear to have fundamentally changed the morphology, dynamics, and habitat abundance and characteristics of lowland rivers across scales from channel unit to valley bottom. Based on our field studies, rivers had substantially more and deeper pools historically. Archival data and field studies indicate that wood jams were integral to creating and maintaining a dynamic, anastomosing river pattern with numerous floodplain channels and abundant edge habitat and routed floodwaters and sediment onto floodplains. Establishing the condition of the riverine landscape before European settlement sets a reference against which to evaluate contemporary conditions and develop restoration objectives.

Experimental Study on Formation Cause of Sink Reach’s River Pattern of Alluvial River Flowing into the Lake

2012 ◽  
Vol 212-213 ◽  
pp. 461-465
Author(s):  
Jun Chen ◽  
Xiao Feng Zhang ◽  
Hong Chen ◽  
Cai Wen Shu
Keyword(s):  
Lake Level ◽  
Sediment Concentration ◽  
Formation Condition ◽  
Channel Evolution ◽  
Alluvial River ◽  
Factors Influencing ◽  
Main River ◽  
Experiment Method ◽  
Major Factors ◽  
River Pattern

The formation cause of sink reach’s river pattern of the alluvial river flowing into the lake was studied by the experiment method. The results showed that: the change of lake level was the important formation condition of the alluvial river’s sink reach. The sediment concentration, the riverbed gradient were the major factors influencing the river pattern’s evolution of the sink reach. When the sediment concentration of upstream river was less, the sink reach was inclined to form a straight river, and with the increase of the sediment concentration, the bifurcated river was the chief river pattern. When the sediment concentration increased to a certain value, the sink reach was inclined to form a wandering river. When the riverbed gradient was less, the sink reach was inclined to form a bifurcated river, and with the increased of the gradient, the wandering river was the main river pattern. The sediment diameter affected channel evolution, but the influence extent was less.

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