Observations of the Specific Resistance in the Øresund

1997 ◽  
Vol 28 (3) ◽  
pp. 217-232 ◽  
Author(s):  
FI. Jakobsen ◽  
M. J. Lintrup ◽  
J. Steen Møller
Keyword(s):  
High Resolution ◽  
Energy Equation ◽  
Specific Resistance ◽  
Flow Direction ◽  
Parameter Variation ◽  
Bottom Friction ◽  
Flow Energy ◽  
Linear Resistance ◽  
Error Dynamics ◽  
Integral Energy

The specific resistance and three other secondary coefficients in the instantaneous integral energy equation describing the flow in the Øresund strait, are accurately estimated from over two years of high resolution measurements. Parameter variation due to stratification, effectively insulating the flow from the effect of bottom friction, is demonstrated and quantified. Also, parameter variation with the flow direction is quantified. Residual error dynamics is discussed and described. The relevance of an additional linear resistance term in the flow energy equation is discussed.

The non-flow energy equation

Thermofluids ◽  
1996 ◽  
pp. 25-27
Author(s):  
Keith Sherwin ◽  
Michael Horsley
Keyword(s):  
Energy Equation ◽  
Flow Energy

scholarly journals Reading the bed morphology of a mountain stream: a geomorphometric study on high-resolution topographic data

2010 ◽  
Vol 14 (2) ◽  
pp. 393-405 ◽  
Author(s):  
S. Trevisani ◽  
M. Cavalli ◽  
L. Marchi
Keyword(s):  
High Resolution ◽  
Ad Hoc ◽  
Flow Direction ◽  
Spatial Scales ◽  
Mountain Stream ◽  
Topographic Data ◽  
The Difference ◽  
Morphological Differences ◽  
High Level ◽  
Local Anomalies

Abstract. High-resolution topographic data expand the potential of quantitative analysis of the earth surface, improving the interpretation of geomorphic processes. In particular, the morphologies of the channel beds of mountain streams, which are characterised by strong spatial variability, can be analysed much more effectively with this type of data. In this study, we analysed the aerial LiDAR topographic data of a headwater stream, the Rio Cordon (watershed area: 5 km2), located in the Dolomites (north-eastern Italy). The morphology of the channel bed of Rio Cordon is characterised by alternating step pools, cascades, and rapids with steps. We analysed the streambed morphology by means of ad hoc developed morphometric indices, capable of highlighting morphological features at a high level of spatial resolution. To perform the analysis and the data interpolation, we carried out a channel-oriented coordinate transformation. In the new coordinate system, the calculation of morphometric indices in directions along and transverse to the flow direction is straightforward. Three geomorphometric indices were developed and applied as follows: a slope index computed on the whole width of the channel bed, directional variograms computed along the flow direction and perpendicular to it, and local anomalies, calculated as the difference between directional variograms at different spatial scales. Directional variograms in the flow direction and local anomalies have proven to be effective at recognising morphologic units, such as steps, pools and clusters of large boulders. At the spatial scale of channel reaches, these indices have demonstrated a satisfactory capability to outline patterns associated with boulder cascades and rapids with steps, whereas they did not clearly differentiate between morphologies with less marked morphological differences, such as step pools and cascades.

Viscous Flows Formed The Branched Ridges Of Antoniadi Crater, Mars

2021 ◽  
Author(s):  
Nicolas Mangold ◽  
Livio Tornabene ◽  
Susan Conway ◽  
Anthony Guimpier ◽  
Axel Noblet ◽  
...  
Keyword(s):  
High Resolution ◽  
Imaging System ◽  
Flow Direction ◽  
Viscous Flows ◽  
Engineering Teams ◽  
The North ◽  
Space Agency ◽  
Imaging Science ◽  
Italian Space Agency ◽  
University Of Bern

<p>Antoniadi basin is a 330 km diameter Noachian basin localized in the East of Arabia Terra that contains a network of ridges with a tree-like organization. Branched ridges, such as these can form by a variety of processes including the inversion of fluvial deposits, thus potentially highlighting aqueous processes of interest for understanding Mars’ climate evolution. Here, we test this hypothesis by analyzing in details data from Colour and Stereo Surface Imaging System (CaSSIS), High Resolution Imaging Science Experiment (HiRISE) and High Resolution Stereo Camera (HRSC).</p><p>Branched ridges are up to 10 km long and from 10 to 200 m wide without obvious organization in width. The branched ridges texture is rubbly with the occurrence of blocks up to ~1 m in size and a complete lack of layering. A HiRISE elevation model shows the local slope is of 0.2° toward South, and thus contrary to the apparent network organization (assuming tributary flows). There is no indication of exhumation of these ridges from layers below the current plains surface. Our observations are not consistent with the interpretation of digitate landforms such as inverted channels: (i) The rubbly texture lacking any layering at meter scale is distinct from inverted channels as observed elsewhere on Mars. (ii) Heads of presumed inverted channels display a lobate shape unlike river springs. (iii) There is no increase in width from small branches toward North as expected for channels with increasing discharge rates downstream. (iv) The slope toward South is contrary to the inferred flow direction to the North. The detailed analysis of these branched ridges shows many characteristics difficult to reconcile with inverted channels formed by fluvial channels flowing northward. Subglacial drainages are known to locally flow against topography, but they are rarely dendritic.<strong> </strong>Assuming that deposition occurred along the current slope, thus from North to South, the organization of the network requires a control by distributary channels rather than tributary ones. Distributary channels are possible for fluvial flows, but generally limited to braiding regimes or deltaic deposits, of which no further evidence is observed here. The lobate digitate shapes of the degree 1 branches are actually more in line with deposits of viscous flows, thus as terminal branches. Such an interpretation is consistent with lava or mudflows that formed along the current topography. The next step in this study will be to determine more precisely the rheology of these unusual flows.</p><p><strong>Acknowledgments:</strong> French authors are supported by the CNES. The authors wish to thank the spacecraft and instrument engineering teams. CaSSIS is a project of the University of Bern and funded through the Swiss Space Office via ESA’s PRODEX. The instrument hardware development was also supported by the Italian Space Agency (ASI) (agreement no. I/018/12/0), INAF/Astronomical Observatory of Padova, and the Space Research Center (CBK) in Warsaw. Support from SGF (Budapest), the Univ. of Arizona (Lunar and Planet. Lab.) and NASA are gratefully acknowledged.</p>

scholarly journals LiDAR derived high resolution topography: the next challenge for the analysis of terraces stability and vineyard soil erosion

2013 ◽  
Vol 44 (2s) ◽  
Author(s):  
Federico Preti ◽  
Paolo Tarolli ◽  
Andrea Dani ◽  
Simone Calligaro ◽  
Massimo Prosdocimi
Keyword(s):  
High Resolution ◽  
Soil Erosion ◽  
Slope Failure ◽  
Flow Direction ◽  
Laser Scanner ◽  
Airborne Lidar ◽  
Wall Structure ◽  
Terrestrial Laser Scanner ◽  
Erosion Risk ◽  
Soil Erosion Risk

The soil erosion in the vineyards is a critical issue that could affect their productivity, but also, when the cultivation is organized in terraces, increase the risk due to derived slope failure processes. If terraces are not correctly designed or maintained, a progressively increasing of gully erosion affects the structure of the walls. The results of this process is the increasing of connectivity and runoff. In order to overcome such issues it is really important to recognize in detail all the surface drainage paths, thus providing a basis upon which develop a suitable drainage system or provide structural measures for the soil erosion risk mitigation. In the last few years, the airborne LiDAR technology led to a dramatic increase in terrain information. Airborne LiDAR and Terrestrial Laser Scanner derived high-resolution Digital Terrain Models (DTMs) have opened avenues for hydrologic and geomorphologic studies (Tarolli et al., 2009). In general, all the main surface process signatures are correctly recognized using a DTM with cell sizes of 1 m. However sub-meter grid sizes may be more suitable in those situations where the analysis of micro topography related to micro changes is critical for slope failures risk assessment or for the design of detailed drainage flow paths. The Terrestrial Laser Scanner (TLS) has been proven to be an useful tool for such detailed field survey. In this work, we test the effectiveness of high resolution topography derived by airborne LiDAR and TLS for the recognition of areas subject to soil erosion risk in a typical terraced vineyard landscape of “Chianti Classico” (Tuscany, Italy). The algorithm proposed by Tarolli et al. (2013), for the automatic recognition of anthropic feature induced flow direction changes, has been tested. The results underline the effectiveness of LiDAR and TLS data in the analysis of soil erosion signatures in vineyards, and indicate the high resolution topography as a useful tool to improve the land use management of such areas. The stability conditions have been analyzed under the influence of the measured geometry alterations of the wall structure.

Imaging of Single Phase Flow in Porous Media by High Resolution MRI

2010 ◽  
Vol 113-116 ◽  
pp. 126-131 ◽  
Author(s):  
Lan Lan Jiang ◽  
Yong Chen Song ◽  
Yu Liu ◽  
Yue Chao Zhao ◽  
Ning Jun Zhu ◽  
...  
Keyword(s):  
Porous Media ◽  
High Resolution ◽  
Velocity Distribution ◽  
Flow Direction ◽  
Spin Echo ◽  
Flow Distribution ◽  
Flow In Porous Media ◽  
Mean Velocity ◽  
High Resolution Mri ◽  
Spin Echo Sequence

This paper presents the single flow in porous media to investigate CO2 flow velocity in porous media.We used high resolution MRI to visualize the fluid flow distribution and measure axial mean velocity in porous media.In the experiment, the porous media sample was packed with glass beads, with a porosity of around 0.4. Based the traditional spin echo sequence, we modified the sequence with flow encoding gradients in the flow direction .The sample was saturated. The water flow rates were 1ml/min、2ml/min、3ml/min and 5ml/min,respectively. First, the sequence was calibrated by pipe flow without porous media. As expected, the experimental images show parabolic velocity distribution. The velocity in the centre is high. Then the sample was measured with the same sequence. The images show that the velocity distribution is homogeneous in the porous media. In the boundary of the sample, the velocities are low because of wall-effect. Moreover, the mean velocities calculated from MRI images agree with the real velocities.These errors between calculated velocities and real velocities are small. It may be reduced by changing the experiment conditions.MRI is a useful technology for measuring flow in porous media.

Wflow_sbm, a spatially distributed hydrologic model: from global data to local applications

2020 ◽  
Author(s):  
Willem van Verseveld ◽  
Hélène Boisgontier ◽  
Laurène Bouaziz ◽  
Dirk Eilander ◽  
Arjen Haag ◽  
...  
Keyword(s):  
High Resolution ◽  
Flow Direction ◽  
Hydrologic Model ◽  
Rooting Depth ◽  
Parameter Estimates ◽  
Model Parameters ◽  
Point Scale ◽  
Climate Zones ◽  
Area Of Interest ◽  
Global Data

<p>In this contribution we present the wflow_sbm hydrologic model concept, which is a conceptual bucket-style hydrologic model based on simplified physical relationships including kinematic wave routing for surface and subsurface lateral flow. The model maximizes the use of global data for local applications and allows us to automatically setup a high resolution (~1km<sup>2</sup>) wflow_sbm model for any basin in the world. For most discharge gauging stations in selected basins from different climate zones, wflow_sbm showed promising results without further calibration. Depending on the geographical area of interest two model parameters, besides anthropogenic interference like reservoir and lake management, show most sensitivity: rooting depth and horizontal saturated hydraulic conductivity.</p><p>We extended the parameter estimation of the wflow_sbm hydrological model for the Rhine basin (Imhoff et al, 2019) with point-scale (pedo)transfer-functions (PTFs) in conjunction with scaling operators as applied in Multiscale Parameter Regionalization (MPR) to the global scale at high resolution (~1km<sup>2</sup>). The state-of-the-art hydro-MERIT dataset at 3 arcsec resolution (Yamazaki et al. (2019)) is scaled to model resolution whilst conserving the drainage network using a newly developed extended Effective Area Method (EAM) for flow direction scaling which builds on the original EAM (Yamazaki et al. 2009). Compared to EAM and the double maximum method, the extended EAM method shows improved skill. The automated model setup derives subgrid information about land slope, river slope and length. River widths are derived from power law relationships between hydro-MERIT river widths and global discharge estimates through multiple linear regression based on GRDC data, precipitation and upstream area with clustering on climate zones. Soil hydraulic parameters are derived from the 250m ISRIC SoilGrids product using PTFs. Furthermore, parameters for interception and rooting depth are derived and upscaled using global or regional land cover maps. Monthly LAI profiles are derived from MODIS (500m) and upscaled. Lake and reservoir parameters are derived from HydroLAKES and GRanD, respectively. The models are run using forcing from globally available data sets like ERA5 and CHIRPS.</p><p> </p><p>Imhoff, R., van Verseveld, W., Osnabrugge, B., A. Weerts, Scaling point-scale pedotransfer functions to seamless large-domain parameter estimates for high-resolution distributed hydrological modelling: An example for the Rhine river, submitted to WRR, 2019.</p><p>Yamazaki D., D. Ikeshima, J. Sosa, P.D. Bates, G.H. Allen, T.M. Pavelsky, MERIT Hydro: A high-resolution global hydrography map based on latest topography datasets, Water Resources Research, 2019, doi: 10.1029/2019WR024873.</p><p>Yamazaki, D., T. Oki., and S. Kanae, Deriving a global river network map and its sub‐grid topographic characteristics from a fine‐resolution flow direction map, Hydrol. Earth Syst. Sci., 13, 2241– 2251, 2009.</p>

Early Detection of the Metallization Quality Using Moderately Accelerated Electromigration Stress Conditions

1998 ◽  
Vol 516 ◽  
Author(s):  
A. Scorzoni ◽  
I. De Munari ◽  
M. Impronta ◽  
R. Balboni ◽  
N. Kelaidis ◽  
...  
Keyword(s):  
High Resolution ◽  
Microstructural Analysis ◽  
Process Variations ◽  
Life Time ◽  
Stress Conditions ◽  
Production Test ◽  
Wafer Level ◽  
Line Production ◽  
Linear Resistance ◽  
Standard Life

AbstractIn this work we use a wafer-level, High Resolution Resistance Measuring Technique (HRRMT) to detect fabrication faults of Al-Cu interconnections. Experiments have been performed on two distinct sets of metal lines. The first set includes two lots of 4 μm wide lines which, once tested at moderately accelerated stress conditions, gave largely different life times. A microstructural analysis confirmed a major defectivity of the lot with shorter life time. An accurate examination of the early resistance variations revealed the presence of two distinct and subsequent phases, namely an initial pseudo-parabolic resistance increase followed by a linear resistance drop. Significant differences between the resistance behaviour of the two lots were detected during the first stage, lasting a few hours. Measurable differences could even be detected in the first few minutes. A second group of experiments was launched in order to assess the capability of HRRMT as in-line monitors. Samples from four wafers, one reference wafer and three wafers with intentional process variations, have been tested using our HRRMT at constant temperature and current, simulating an in-line production test. The standard life time of the four wafers have also been collected. Preliminary measurements highlight that a change of life time due to process variation corresponds to changes of the resistance behaviour in the first hours of test. These results pave the way for a new application of high resolution methods to assess the quality of a metallization system in a reasonable amount of time.

scholarly journals Reading the bed morphology of a mountain stream: a geomorphometric study on high-resolution topographic data

2009 ◽  
Vol 6 (6) ◽  
pp. 7287-7319 ◽  
Author(s):  
S. Trevisani ◽  
M. Cavalli ◽  
L. Marchi
Keyword(s):  
High Resolution ◽  
Ad Hoc ◽  
Flow Direction ◽  
Spatial Scales ◽  
Mountain Stream ◽  
Topographic Data ◽  
The Difference ◽  
Morphological Differences ◽  
High Level ◽  
Local Anomalies

Abstract. High-resolution topographic data expand the potential of quantitative analysis of the earth surface, improving the interpretation of geomorphic processes. In particular, the morphologies of the channel beds of mountain streams, which are characterised by strong spatial variability, can be analysed much more effectively with this type of data. In the present study, we analysed the aerial LiDAR topographic data of a headwater stream, the Rio Cordon (watershed area: 5 km2), located in the Dolomites (north-eastern Italy). The morphology of the channel bed of Rio Cordon is characterised by alternating step pools, cascades, and rapids with steps. We analysed the streambed morphology by means of ad hoc developed morphometric indices, capable of highlighting morphological features at a high level of spatial resolution. To perform the analysis and the data interpolation, we carried out a channel-oriented coordinate transformation. In the new coordinate system, the calculation of morphometric indices in directions along and transverse to the flow direction is straightforward. Three geomorphometric indices were developed and applied as follows: a slope index computed along the whole width of the channel bed, directional variograms computed along the flow direction and perpendicular to it, and local anomalies, calculated as the difference between directional variograms at different spatial scales. Directional variograms in the flow direction and local anomalies have proven to be effective at recognising morphologic units, such as steps, pools and clusters of large boulders. At the spatial scale of channel reaches, these indices have demonstrated a satisfactory capability to outline patterns associated with boulder cascades and rapids with steps, whereas they did not clearly differentiate between morphologies with less marked morphological differences, such as step pools and cascades.

An Analysis of the Loss Mechanisms in Low-Speed Axial Fans Using Scaling Arguments and Their Effects on a Proposed New Definition of Efficiency

2006 ◽  
Author(s):  
Douglas R. Neal
Keyword(s):  
Energy Equation ◽  
Pressure Rise ◽  
Axial Fan ◽  
Low Speed ◽  
Static Efficiency ◽  
Axial Fans ◽  
Integral Energy ◽  
Definition Of ◽  
Scaling Arguments ◽  
Ventilation Fan

Low-speed axial fans are used extensively for ventilation purposes in industrial and commercial buildings. In agricultural applications, such as a greenhouse, the ventilation is critical, since entire crops can be damaged or destroyed if a clean air supply is not maintained. The cost-marginal nature of these businesses demand that operating costs be kept to a minimum, hence there is a strong motivation to develop higher efficiency ventilation fans. An analysis of a low-speed axial fan has been developed using a control volume-based energy balance. The specific fan is an axial ventilation fan that is commonly found on agricultural facilities such as green-houses or livestock buildings. These fans induce an airflow from a large building into the open atmosphere at very low (or often effectively zero) system restriction or pressure rise. The definition for static efficiency, which is commonly used by the axial fan community, is examined and its implications are discussed. Since static efficiency yields a zero-percent efficient fan at a zero pressure rise operating condition, the ventilation fan industry has developed an alternate definition of efficiency. This alternate definition of efficiency, along with other proposed definitions, are described and their limitations are discussed. A new definition of efficiency is introduced and its basis in the integral energy equation is identified. The primary loss mechanisms of low-speed axial turbomachinery are discussed and scaling arguments are developed and used in the integral energy equation analysis. The results of this analysis yield an expanded expression of efficiency in which the loss mechanism terms can be empirically determined. When analyzed with values for a particular fan system, these results can further be used as the basis for an optimization study of that fan system.

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