Bottom Step Research Articles

THE CLIMATE CHANGES IMPACT ON THE RIVER CHANNELS AND VALLEY BOTTOMS IN THE EASTERN SIBERIA

Morphology and morphometry of the buried and contemporary valleys bottoms in two mountain placer districts of the Eastern Siberia were analyzed. The Lena district is located within Vitima–Patom plateau on the right bank of the Vitim river, the Kular one is located in the interfluve of the rivers Yana and Omoloy. Using the topographic maps and paleogeomorphological schemes compiled on the basis of drilling data, we defined the morphodynamic types of channels, morphometric parameters (the width of the bottom step, the bend deflection of the meander) and the morphology of the bottoms of the buried and modern valleys. The patterns of their change were traced during several geological periods with different climatic conditions specified by paleolandscape method. Morphological and morphometric characteristics of the bottoms and beds of mountain valleys depend on the altitudinal zonation. In the mid-mountain relief of the Lensky district, even at the considerable changes of climate, morphodynamic type of riverbed, bottom morphology and morphometric parameters of buried and modern valleys are practically identical. More significant is the impact of climate change on the bottoms of valleys and channels in the Kular district. Here, in the relief of low-mountains and plateaus, with a cooling of the climate and the decrease of rainfall, the width of the bottoms of the modern valleys is significantly reduced compared to buried valleys, formed in warm humid climate of the Paleogene. Using the results of long-term observations on the mountain river Bzyb (Caucasus) the mechanism underlying these differences was revealed. It is associated with the intensity of deformation of bed forms depending on the nature of the relief terrain and water availability.

A comparison between bottom-discontinuity numerical treatments in the DG framework

In this work, using an unified framework consisting in third-order accurate discontinuous Galerkin schemes, we perform a comparison between five different numerical approaches to the free-surface shallow flow simulation on bottom steps.Together with the study of the overall impact that such techniques have on the numerical models we highlight the role that the treatment of bottom discontinuities plays in the preservation of specific asymptotic conditions. In particular, we consider three widespread approaches that perform well if the motionless steady state has to be preserved and two approaches (one previously conceived by the first two authors and one original) which are also promising for the preservation of a moving-water steady state.Several one-dimensional test cases are used to verify the third-order accuracy of the models in simulating an unsteady flow, the behavior of the models for a quiescent flow in the cases of both continuous and discontinuous bottom, and the good resolution properties of the schemes. Moreover, specific test cases are introduced to show the behavior of the different approaches when a bottom step interact with both steady and unsteady moving flows.

Atomic layer deposition of ZrO2 thin film on Si(100) using {η5:η1-Cp(CH2)3NMe}Zr(NMe2)2/O3 as precursors

Atomic layer deposition (ALD) of ZrO2 thin films was investigated using a linked cyclopentadienyl-amido compound of zirconium, {η5:η1-Cp(CH2)3NMe}Zr(NMe2)2 with ozone. The ALD-window was established as 300–380°C with a growth rate of about 0.95Å/cycle. A good film conformality of 0.95 for 5.7–6.1nm-thick film was obtained for bottom and sidewall step coverages of 0.93 and 0.95, respectively. The ALD at 330°C yielded a ZrO2 having good crystallinity. The film showed low impurity levels and a strong tendency to form the tetragonal/cubic phases despite a low film thickness of 8.58nm (root-mean-square roughness=0.49nm). Better ALD performance was obtained with this linked precursor than with the commonly used CpZr(NMe2)3 precursor. Furthermore, theoretical calculations for the ALD processes on hydroxylated Si wafer surfaces were performed by using density function theory. Initial growth mechanism of ZrO2 from CpZr(NMe2)3 and {η5:η1-Cp(CH2)3NMe}Zr(NMe2)2 were proposed on atomic-scale structure.

STATISTICAL BUILDING ROOF RECONSTRUCTION FROM WORLDVIEW-2 STEREO IMAGERY

Abstract. 3D building reconstruction from point clouds is an active research topic in remote sensing, photogrammetry and computer vision. Most of the prior research has been done on 3D building reconstruction from LiDAR data which means high resolution and dense data. The interest of this work is 3D building reconstruction from Digital Surface Models (DSM) of stereo image matching of space borne satellite data which cover larger areas than LiDAR datasets in one data acquisition step and can be used also for remote regions. The challenging problem is the noise of this data because of low resolution and matching errors. In this paper, a top-down and bottom-up method is developed to find building roof models which exhibit the optimum fit to the point clouds of the DSM. In the bottom up step of this hybrid method, the building mask and roof components such as ridge lines are extracted. In addition, in order to reduce the computational complexity and search space, roofs are classified to pitched and flat roofs as well. Ridge lines are utilized to estimate the roof primitives from a building library such as width, length, positions and orientation. Thereafter, a topdown approach based on Markov Chain Monte Carlo and simulated annealing is applied to optimize roof parameters in an iterative manner by stochastic sampling and minimizing the average of Euclidean distance between point cloud and model surface as fitness function. Experiments are performed on two areas of Munich city which include three roof types (hipped, gable and flat roofs). The results show the efficiency of this method in even for this type of noisy datasets.

Transformation of internal waves passing over a bottom step

The transformation of small-amplitude internal waves on the oceanic shelf is studied numerically. The transmission and reflection coefficients are found for the simplified step-wise model of the oceanic shelf in a two-layer fluid. The approximate formulae are proposed for the transformation coefficients as functions of incident wavenumber, density ratio of layers, depth of the pycnocline and height of the bottom step. Results of direct numerical modelling of internal wave transformation are obtained and presented as functions of all aforementioned parameters. It is shown that there is a good agreement between the outcomes of approximate theory and numerical data. Both the theoretical and the numerical results agree well with the law of energy flux conservation.

Transformation of surface waves over a bottom step

We analyze in detail the problem of the transformation of surface gravity waves over a bottom step in a basin of arbitrary depth in the linear approximation. We found that strict analytical results can be obtained only when a denumerable set of modes condensed near the step is taken into account. At the same time, one can use the formulas suggested in this work for the practical calculations. They provide an accuracy of 5% for the wave transmission coefficient. The specific peculiarities of transformation coefficients are discussed, including their nonmonotonic dependence on the parameters, asymptotic behavior at strong depth variations, etc. The data of a direct numerical simulation of wave transformation over a step are presented, which are compared with the exact and approximate formulas. The coefficients of excitation of modes condensed near the step by an incident quasi-monochromatic wave are found. A relationship between the transformation coefficients that follows from the conservation law of wave energy flux is found.

Exact Riemann solutions to shallow water equations

We determine completely the Riemann solutions to the shallow water equations with a bottom step, including the dry bed problem. The nonstrict hyperbolicity of this first-order system of partial differential equations leads to resonant waves and nonunique solutions. To address these difficulties we construct the L–M and R–M curves in the state space. For the bottom step elevated from left to right, we classify the L–M curve into five different cases and the R–M curve into two different cases based on the subcritical and supercritical Froude number of the Riemann initial data as well as the jump of the bottom step. The behaviors of all basic cases of the L–M and R–M curves are fully analyzed. We observe that the non–uniqueness of the Riemann solutions is due to bifurcations on the L–M or R–M curves. The possible solutions including classical waves and resonant waves as well as dry bed state are solved in a uniform framework for any given Riemann initial data.

A Broad-crested Weir Boundary Condition in Finite Volume Shallow-water Numerical Models

In the literature, the weir boundary condition is usually implemented imposing the weir formula at the boundaries, but this is rigorous only in subcritical steady conditions, and a more general approach is required during transients. With acceptable approximation, the non-submerged broad-crested weir behaves as a bottom step where the energy is conserved and critical conditions are attained at the top. Taking advantage of this observation, the analytic solution of the Riemann problem for the Shallow-water Equations over a dry bottom step is considered in this paper, and the momentum and mass fluxes of the analytic solution of the Riemann problem are used to impose weakly the broad-crested non-submerged weir boundary condition in a Finite Volume scheme.

Transformation of Narrowband Wavetrains of Surface Gravity Waves Passing over a Bottom Step

The problem of transformation of quasimonochromatic wavetrains of surface gravity waves with narrow spatial-temporal spectra on the bottom shelf is considered in the linear approximation. By means of numerical modeling, the transmission and reflection coefficients are determined as functions of the depth ratio and wave number (frequency) of an incident wave. The approximation formulae are proposed for the coefficients of wave transformation. The characteristic features of these formulae are analyzed. It is shown that the numerical results agree quite satisfactorily with the proposed approximation formulae.

Transformation of internal solitary waves at the "deep" and "shallow" shelf: satellite observations and laboratory experiment

Abstract. An interaction of internal solitary waves with the shelf edge in the time periods related to the presence of a pronounced seasonal pycnocline in the Red Sea and in the Alboran Sea is analysed via satellite photos and SAR images. Laboratory data on transformation of a solitary wave of depression while passing along the transverse bottom step were obtained in a tank with a two-layer stratified fluid. The certain difference between two characteristic types of hydrophysical phenomena was revealed both in the field observations and in experiments. The hydrological conditions for these two processes were named the "deep" and the "shallow" shelf respectively. The first one provides the generation of the secondary periodic short internal waves – "runaway" edge waves – due to change in the polarity of a part of a soliton approaching the shelf normally. Another one causes a periodic shear flow in the upper quasi-homogeneous water layer with the period of incident solitary wave. The strength of the revealed mechanisms depends on the thickness of the water layer between the pycnocline and the shelf bottom as well as on the amplitude of the incident solitary wave.

Effect of Vertical Baffle Installation on Forced Convective Heat Transfer in Channel Having a Backward Facing Step

In this study, forced convective heat transfer is considered in channel over a backward facing step having a baffle on the top wall. Four different geometries with different expansion ratios and different type of baffles are numerically investigated. The study clearly shows that the geometry with expansion ratio 2 and solid baffle has the highest Nusselt number compared to other geometries. Considering both Nusselt number and skin friction coefficient for all four geometries clearly illustrated an increase in average Nusselt number by increasing the expansion ratio. This study clearly shows that mounting a slotted baffle at the top wall instead of a solid baffle caused a decline in average Nusselt number. It is also found that for geometry with expansion ratio of 3 and a slotted baffle on the top of the channel, skin friction coefficient in both bottom wall and step wall has its minimal compared to other geometries.

Internal solitary wave transformation over a bottom step: Loss of energy

In this paper, we extend the numerical study of Maderich et al. [“Interaction of a large amplitude interfacial solitary wave of depression with a bottom step,” Phys. Fluids 22, 076602 (2010)10.1063/1.3455984] on the interaction of an interfacial solitary wave with a bottom step, considering (i) the energy loss of solitary waves of both polarities interacting with a bottom step and (ii) features of the transformation of a large-amplitude internal solitary waves at the step. We show that the dependence of energy loss on the step height is not monotonic, but has different maximum positions for different incident wave polarities. The energy loss does not exceed 50% of the energy of an incident wave. The results of our numerical modeling are compared with some recent results from laboratory tank modeling.

Bioenergy, sustainability, and the second law

Bioenergy, sustainability, and the second law

Molecular Dynamics Study on Enhanced Cu Coverage of Trench Filling with Low-Index Ta Surfaces

The Cu coverage of trench filling enhanced by different low-index surfaces of tantalum in physical vapor deposition is studied by molecular dynamics simulation with the embedded atom method (EAM) as the interaction potential for the present alloy metal system. The deposition morphologies and bottom step coverage enhancement of trenches with three different aspect ratios are examined. It is found that the Cu adatom on Ta(110) with uniform and low surface diffusion barrier energy and that on Ta(111) with high surface energy lead to the improvement of the surface diffusion of Cu adatoms. The shadowing effect is inhibited on Ta(110) and Ta(111) such that the bottom step coverage of the trench is enhanced markedly at an early stage and the final coverage of trench filling is improved significantly. Also, the texture of deposition on the trench with Ta(110) has a uniform structure owing to the low surface energy, while that with Ta(111) has a nonuniform structure owing to the high surface energy on the sidewall.

Side Magnet Designs and Magnetic Field Effects on Effective Gap Filling of Longthrow Sputtering PVD for 3DIC Application

This study used Finite Volume Method to simulate the magnetic profile of PVD (physical vapor deposition) chamber. It can be applied to different kinds of magnet arrangements to the longthrow sputtering PVD. For this long throw PVD, the best optimized process conditions and results from simulations included effects from chamber adaptor height, side magnet space, and magnet arangements. The side magnets consist of a total of 44 sets for one supporter around the chamber adaptor. Each set has three magnets. Each magnet has the magnetic field strength of 5,500 Gauss. The adaptor of gap filling chamber has a height of 120 mm and 44 sets of magnets around the adaptor. The polarity of side magnets is the same as the top magnets of the chamber. These magnets can very effectively increase of electron mobility and collision frequency with sputtered atoms. The plasma simulation result shows that the ionization rate on supttered atoms can be up to 26% from such a longthrow PVD system along with such magnets arrangement. Therefore, it shows a significant improvement on bottom side-wall step coverage in via hole up to 45%. The deposition rate increases by 40%. In addition, by adjusting RF bias and resputtering power, further improvement with 3/4 depth of side-wall step coverage by 30% and corner step coverage by 70% can be obtained. This study uses a simple method to apply to 3DIC gap filling capability for an increase of aspect ratio (AR). The improvement from this longthrow sputtering PVD with side magnets design around the adaptor not only results in low cost target design but also provides a very effective gap filling capability with higher deposition rate for 3DIC application.

Numerical Modeling and Simulation on Seismic Performance of High-Speed Railway Bridge System

In this paper, the responses of high-speed railway bridge subjected to seismic load were investigated by numerical simulation. Elastic deformation will occur in the bridge system under low-level earthquake; however, the bridge system may enter a nonlinear stage under high-level earthquake. The whole finite element model of the bridge system was set up by means of ANSYS software and self-compiled moment-curvature relationship program, the elastic seismic responses of bridge system and the elastic-plastic deformation of piers considering different vehicle speeds are calculated respectively. The calculation results show that, the earthquake responses of bridge system are increase in general with the increase of vehicle speed and earthquake intensity, and the bottom of piers step into elastic-plasticity stage under high-level earthquake, the plastic hinges occurred at the pier bottom, the pier bottom step into the plastic stage, some measures such as lateral reinforced steel encryption should be taken into account to ensure safety.

Growing Big Science in a Small Country: MAX-lab and the Swedish Research Policy System

MAX-lab is a Swedish national synchrotron radiation facility, first established as a small-scale university project in the late 1970s and then gradually developed into a national and international user facility. This article presents a historical study of MAX-lab that illustrates the decentralized character of the Swedish science policy system and especially its lack of aggregation mechanisms for strategically important initiatives such as the establishment of large research infrastructures. The dominating university sector and the absence of strong central governance structures have made Swedish science policy pluralistic, driven from the bottom up, and decentralized. The genesis and development of MAX-lab, while remarkable when compared to other such facilities internationally, is symptomatically Swedish–it has grown from the bottom up and step by step, and thereby managed to become a respected national and international user facility despite unfavorable conditions. The patchy funding model and the lack of coherent policymaking has led to underfunding and an opaque organizational structure, but MAX-lab and its users have nonetheless been of high quality. This article argues that the determination, patience, adaptivity, and, to some extent, ingenuity of the people involved in MAX-lab have compensated for systemic shortcomings and enabled the laboratory to succeed despite the unfavorable conditions.

Improved Step Coverage of Cu Seed Layers by Magnetic-Field-Assisted Ionized Sputtering

The relationship between the ion flux of self-ionized sputtering and the static magnetic field supplied by DC coils was investigated by ion current measurements. The ion flux was clarified in order to increase the substrate ion current. The additional magnetic field perpendicular to the substrate increases the substrate ion current and decreases the side electron current. The suppression of Cu ion diffusion increases the substrate ion current of self-ionized sputtering and the current distribution depends on the magnetic field configuration. A stronger magnetic field in the region of the wafer edge is necessary to increase the substrate ion current. This condition results in an increase in bottom step coverage and any asymmetry at the wafer edge is also corrected.

Hyperconcentrated 1D Shallow Flows on Fixed Bed with Geometrical Source Term Due to a Bottom Step

Free-surface, two-phase flows constituted by water and a significant concentration of sediments (i.e. hyperconcentrated flows), are often studied under the classical 1D shallow-water assumptions. This paper deals with the problem of the numerical simulation of this type of flows in presence of a geometrical source term caused by a discontinuity in the bed. Since we work in the framework of the finite-volume Godunov-type numerical schemes, we focus on the exact and approximated solution to Riemann Problems at cell interfaces with a step-like bed discontinuity. The paper has a twofold aim. First, it provides insights into the properties of the Step Riemann Problems (SRPs), highlighting in particular that a contact wave with special features may develop. Second, it presents a two-step predictor-corrector algorithm for the solution of the SRPs. In the predictor step, a Generalized Roe solver is used in order to provide an estimation of the wave structure arising from the cell-interface, while in the corrector step the exact SRP is solved by means of an efficient iterative procedure. The capabilities of the proposed solver are tested by comparing numerical and exact solutions of some SRPs.

After the Night of the Inheritance

After the Night of the Inheritance Lois Swartz (bio) On the night of the inheritance, Flora swiped the lace tablecloth from the polished mahogany dining table and dropped it on one of the shield-backed dining chairs. "Elise, your uncles are coming to meet with me. And stop making that face. You'll get wrinkles. Why can't you ever listen to me? I'm not serving any food tonight, either." Elise shrugged, covering up her newly pierced ears. She was only twelve and hated every time her mother threatened. She would never marry. She wanted to be the first girl in the family to attend college. Worrying about wrinkles was stupid at twelve when she was just getting interested in boys. "Mom, why do I have to go outside?" But Flora was busy fumbling in her apron pocket for a cigarette before she turned and click-clacked into the kitchen on her three-inch heels. Elise heard kitchen cabinets slamming until Flora shouted "gotcha" and walked back into the dining room. "No one marries girls with wrinkled foreheads. And my sisters-in-law and your cousin Max won't be here either. We're having a family meeting," Flora mumbled with a lit cigarette hanging between her lips. A moment later, Elise's youngest uncle, who had just turned thirty, tiptoed into the living room, squeezing himself between his older brothers sitting on either end of the green couch. "It's time for you to take Elise outside," Flora said to her husband. Elise's father fumbled in the crowded [End Page 97] dining room closet for her sweater. He held the sweater behind her back and she slipped her arms into the sleeves. Elise passed her silent uncles and waved goodbye as her father steered her across the living room to sit outside on the concrete steps. A small light fixture sparkled on the Wissahickon schist, casting shadows on their backs. Streetlights illumined the young curb trees. From inside, a chorus of her mother's siblings' "Pop, l'shalom" wafted through the screen door into flat, unscented air. The peony stems on the lawn greened, presaging the deep pink flowers that the neighbor kids would later trample when running across the contiguous lawns to catch fireflies. Inside, cigarettes and ashtrays were Flora's lifeline. From the sofa, the two older brothers recited their creed: "Pop made a mistake; we have to own the business. If you don't sign over Pop's business to us, we'll go to court and break the will. You have a husband to support you, anyway. If you try forcing us to break his will, we'll break up the family and you really will be sorry, even if you get more money. You already have a husband to support you." Later, Flora spoke to herself, Everyone smoked. I left the dining room doorway and darted in and out of the kitchen to empty ashtrays until I settled on the bottom step in the living room. I didn't know how to fight back. Two years later, a Japanese submarine torpedoed Flora's husband's ship, sending his body to the depths of the Pacific. Flora sank into another season of mourning. When the youngest brother visited, his first stop was the black baby grand from their parents' house. Flora pushed his hands into the piano shouting, "I hate Communists, you're as greedy as your capitalist brothers. All you wanted was my part of Pop s business." He told his older brothers that Flora was temperamental because she was pregnant. After birthing the now fatherless Rebecca, Flora followed her husband into her own depths, the depths of depression. She was her own house of mourning, shaking her head to push back encroaching walls. Each night Flora's dead father visited. He stood staring with his cobalt blue eyes from the foot of her bed. In a soiled nightgown with sagging rickrack trim, Flora spoke to his ghost. In the morning she wiped her hand down the glass medicine cabinet, chanting "No, I will not go under," as she splashed water on concave cheeks and etched forehead, watching her red hair fade...