Hillslope hydrology and stability
Lu, Ning; Godt, Jonathan
2012-01-01
Landslides are caused by a failure of the mechanical balance within hillslopes. This balance is governed by two coupled physical processes: hydrological or subsurface flow and stress. The stabilizing strength of hillslope materials depends on effective stress, which is diminished by rainfall. This book presents a cutting-edge quantitative approach to understanding hydro-mechanical processes across variably saturated hillslope environments and to the study and prediction of rainfall-induced landslides. Topics covered include historic synthesis of hillslope geomorphology and hydrology, total and effective stress distributions, critical reviews of shear strength of hillslope materials and different bases for stability analysis. Exercises and homework problems are provided for students to engage with the theory in practice. This is an invaluable resource for graduate students and researchers in hydrology, geomorphology, engineering geology, geotechnical engineering and geomechanics and for professionals in the fields of civil and environmental engineering and natural hazard analysis.
Sediment transport by runoff on debris-mantled dryland hillslopes
Michaelides, Katerina; Martin, Gareth J.
2012-09-01
Hillslopes supply sediment to river channels, and therefore impact drainage basin functioning and evolution. The relationship between hillslope attributes and sediment flux forms the basis of geomorphic transport laws used to model the long-term topographic evolution of drainage basins, but their specific interactions during individual storm events are not well understood. Runoff-driven erosion of coarse particles, prevalent in dryland environments, presents a particular set of conditions for sediment transport that is poorly resolved in current models. In order to address this gap, we developed a particle-based, force-balance model for sheetwash sediment transport on coarse, debris-mantled hillslopes within a rainfall-runoff model. We use the model to examine how the interplay between hillslope attributes (gradient, length and grain size distribution) and runoff characteristics affects sediment transport, grain-size changes on the hillslope, and sediment supply to the slope base. The relationship between sediment flux and hillslope gradient was found to transition from linear above a threshold to sigmoidal depending on hillslope length, initial grain sizes, and runoff characteristics. Grain sizes supplied to the slope base vary in a complex manner with hillslope attributes but an overall coarsening of the hillslopes is found to occur with increasing gradient, corroborating previous findings from field measurements. Intense, short duration storms result in within-hillslope sediment redistribution and equifinality in sediment supply for different hillslope characteristics, which explain the lack of field evidence for any systematic relationships. Our model findings provide insights into hillslope responses to climatic forcing and have theoretical implications for modeling hillslope evolution in dry lands.
SIZE, STRUCTURE AND FUNCTIONALITY IN SHALLOW COVE COMMUNITIES IN RI
We are using an ecosystem approach to examine the ecological integrity and important habitats in small estuarine coves. We sampled the small undeveloped Coggeshall Cove during the sununer of 1999. The cove was sampled at high tide at every 15 cm of substrate elevation along trans...
COVE 2A Benchmarking calculations using NORIA
Carrigan, C.R.; Bixler, N.E.; Hopkins, P.L.; Eaton, R.R.
1991-10-01
Six steady-state and six transient benchmarking calculations have been performed, using the finite element code NORIA, to simulate one-dimensional infiltration into Yucca Mountain. These calculations were made to support the code verification (COVE 2A) activity for the Yucca Mountain Site Characterization Project. COVE 2A evaluates the usefulness of numerical codes for analyzing the hydrology of the potential Yucca Mountain site. Numerical solutions for all cases were found to be stable. As expected, the difficulties and computer-time requirements associated with obtaining solutions increased with infiltration rate. 10 refs., 128 figs., 5 tabs
Relationship between 137Cs concentration and cultivated history on loessial hillslopes
Wang Xiaoyan; Tian Junliang; Yang Mingyi; Liu Puling
2005-01-01
There are close linkages between soil loss degree and soil disturbance degree by human. So it is a key problem to know that how human activity affects soil loss. To analyse the correlation of 137 Cs loss degree with hillslopes' cultivated histories, the concentrations of 137 Cs on different kinds of loessial hillslopes with different cultivated histories, abandoned ages and different patterns of reforestation are studied. The result shows that there is a linear relationship among 137 Cs areal concentrations, cultivation ages and slope gradients. the regressive equation is as follows: X=2356.79-22.77 t-35.53 S. Variant coefficient of 137 Cs areal concentration is 80.11% among hillslopes with different abandonment ages. It is also deduced that 137 Cs areal concentration is affected primarily by abandonment ages of hillslopes. The 137 Cs loss rates of hillslopes with different vegetation restoration manners show significant differences, as a whole, autogenic restoration 137 Cs area concentrations on hillslopes. (authors)
Hillslope Soils and Life (Invited)
Amundson, R.; Owen, J. J.; Heimsath, A. M.; Yoo, K.; Dietrich, W. E.
2013-12-01
That hillslope processes are impacted by biology has been long understood, but the complexities of the abiotic-biotic processes and their feedbacks are quantitatively emerging with the growing body of pertinent literature. The concept that plants modulate both the disaggregation and transport of soil particles on hillslopes was clearly articulated by G.K. Gilbert. Yet earlier, James Hutton (starting from very different intellectual boundary conditions) argued that soil, which results from the dynamic balance of rock destruction and removal, is a prerequisite for plants - a concept that underscores the need to more deeply examine the feedback of geomorphic processes on terrestrial ecosystems. We compiled the results of recent studies that have been conducted on gentle convex hillslopes across a broad range of rainfall. We found that vegetated landscapes appear to have strong controls on hillslope soil thickness, landscape denudation rates, and soil residence times. The restricted range in residence times - despite large differences in climate - appear in turn to sustain relatively high levels of both nitrogen (N) and phosphorus (P) fertility, suggesting ecological resilience and resistance to non-anthropogenic environmental perturbations. At the most arid end of Earth's climate vegetation disappears, but not all water. The loss of plants shifts soil erosion to abiotic processes, with a corresponding thinning or loss of the soil mantle. This reinforces the hypothesis that a planet without vegetation, but with a hydrologic cycle, would be largely devoid of soil-mantled hillslopes and would be driven toward hillslope morphologies that differ from the familiar convex-up forms of biotic landscapes. While our synthesis of the effects of vegetation on soil production and soil thickness provides a quantitative view of the suggestions of Gilbert, it also identifies that vegetation itself responds to the geomorphic processes, as believed by Hutton. There is a complex
A geomorphic process law for detachment-limited hillslopes
Turowski, Jens
2015-04-01
Geomorphic process laws are used to assess the shape evolution of structures at the Earth's surface over geological time scales, and are routinely used in landscape evolution models. There are two currently available concepts on which process laws for hillslope evolution rely. In the transport-limited concept, the evolution of a hillslope is described by a linear or a non-linear diffusion equation. In contrast, in the threshold slope concept, the hillslope is assumed to collapse to a slope equal to the internal friction angle of the material when the load due to the relief exists the material strength. Many mountains feature bedrock slopes, especially in the high mountains, and material transport along the slope is limited by the erosion of the material from the bedrock. Here, I suggest a process law for detachment-limited or threshold-dominated hillslopes, in which the erosion rate is a function of the applied stress minus the surface stress due to structural loading. The process law leads to the prediction of an equilibrium form that compares well to the shape of many mountain domes.
Half Moon Cove Tidal Project. Feasibility report
1980-11-01
The proposed Half Moon Cove Tidal Power Project would be located in a small cove in the northern part of Cobscook Bay in the vicinity of Eastport, Maine. The project would be the first tidal electric power generating plant in the United States of America. The basin impounded by the barrier when full will approximate 1.2 square miles. The average tidal range at Eastport is 18.2 feet. The maximum spring tidal range will be 26.2 feet and the neap tidal range 12.8 feet. The project will be of the single pool-type single effect in which generation takes place on the ebb tide only. Utilizing an average mean tidal range of 18.2 feet the mode of operation enables generation for approximately ten and one-half (10-1/2) hours per day or slightly in excess of five (5) hours per tide. The installed capacity will be 12 MW utilizing 2 to 6 MW units. An axial flow, or Bulb type of turbine was selected for this study.
Hillslope runoff processes and models
Kirkby, Mike
1988-07-01
Hillslope hydrology is concerned with the partition of precipitation as it passes through the vegetation and soil between overland flow and subsurface flow. Flow follows routes which attenuate and delay the flow to different extents, so that a knowledge of the relevant mechanisms is important. In the 1960s and 1970s, hillslope hydrology developed as a distinct topic through the application of new field observations to develop a generation of physically based forecasting models. In its short history, theory has continually been overturned by field observation. Thus the current tendency, particularly among temperate zone hydrologists, to dismiss all Hortonian overland flow as a myth, is now being corrected by a number of significant field studies which reveal the great range in both climatic and hillslope conditions. Some recent models have generally attempted to simplify the processes acting, for example including only vertical unsaturated flow and lateral saturated flows. Others explicitly forecast partial or contributing areas. With hindsight, the most complete and distributed models have generally shown little forecasting advantage over simpler approaches, perhaps trending towards reliable models which can run on desk top microcomputers. The variety now being recognised in hillslope hydrological responses should also lead to models which take account of more complex interactions, even if initially with a less secure physical and mathematical basis than the Richards equation. In particular, there is a need to respond to the variety of climatic responses, and to spatial variability on and beneath the surface, including the role of seepage macropores and pipes which call into question whether the hillside can be treated as a Darcian flow system.
Flow variability and hillslope hydrology
Huff, D D; O' Neill, R V; Emanuel, W R; Elwood, J W; Newbold, J D
1982-01-01
Examination of spatial variability of streamflow in headwater areas can provide important insight about factors that influence hillslope hydrology. Detailed observations of variations in stream channel input, based on a tracer experiment, indicate that topography alone cannot explain flow variability. However, determination of changes in channel input on a small spatial scale can provide valuable clues to factors, such as structural geology that control subsurface flows.
Hillslope hydrological modeling : the role of bedrock geometry and hillslope-stream interaction
Shahedi, K.
2008-01-01
Keywords: Hillslope hydrology, hydrological modeling, bedrock geometry, boundary condition, numerical solution.
This thesis focuses on hillslope subsurface flow as a dominant control on the hydrological processes defining the catchment response to rainfall. Due to the difficulties
Marçais, J.; Gupta, H. V.; De Dreuzy, J. R.; Troch, P. A. A.
2016-12-01
Geomorphological structure and geological heterogeneity of hillslopes are major controls on runoff responses. The diversity of hillslopes (morphological shapes and geological structures) on one hand, and the highly non linear runoff mechanism response on the other hand, make it difficult to transpose what has been learnt at one specific hillslope to another. Therefore, making reliable predictions on runoff appearance or river flow for a given hillslope is a challenge. Applying a classic model calibration (based on inverse problems technique) requires doing it for each specific hillslope and having some data available for calibration. When applied to thousands of cases it cannot always be promoted. Here we propose a novel modeling framework based on coupling process based models with data based approach. First we develop a mechanistic model, based on hillslope storage Boussinesq equations (Troch et al. 2003), able to model non linear runoff responses to rainfall at the hillslope scale. Second we set up a model database, representing thousands of non calibrated simulations. These simulations investigate different hillslope shapes (real ones obtained by analyzing 5m digital elevation model of Brittany and synthetic ones), different hillslope geological structures (i.e. different parametrizations) and different hydrologic forcing terms (i.e. different infiltration chronicles). Then, we use this model library to train a machine learning model on this physically based database. Machine learning model performance is then assessed by a classic validating phase (testing it on new hillslopes and comparing machine learning with mechanistic outputs). Finally we use this machine learning model to learn what are the hillslope properties controlling runoffs. This methodology will be further tested combining synthetic datasets with real ones.
Arena Cove, California Tsunami Forecast Grids for MOST Model
National Oceanic and Atmospheric Administration, Department of Commerce — The Arena Cove, California Forecast Grids provides bathymetric data strictly for tsunami inundation modeling with the Method of Splitting Tsunami (MOST) model. MOST...
Selected Hydrologic Data for Sand Cove Wash, Washington County, Utah
Norton, Aaron; Susong, David D
2004-01-01
.... Hydrologic data collected in this study are described and listed in this report. Six boreholes were drilled in Sand Cove Wash to determine the vertical and spatial distribution of the alluvial deposits and their hydrologic...
Elfin Cove, Alaska Tsunami Forecast Grids for MOST Model
National Oceanic and Atmospheric Administration, Department of Commerce — The Elfin Cove, Alaska Forecast Grids provides bathymetric data strictly for tsunami inundation modeling with the Method of Splitting Tsunami (MOST) model. MOST is a...
Hillslope evolution in landscapes dominated by layered rocks
Glade, R.; Anderson, R. S.
2016-12-01
Geologic structure and lithology can exert fundamental control over hillslope evolution. Landforms common across the western US, such as mesas, hogbacks, flatirons, and symmetric ridges bounding dikes, develop in the face of differential weathering of layered rocks in a horizontal, tilted, or vertical structural orientation. These features exhibit a characteristic form distinct from that of homogeneous, soil-mantled hillslopes; linear-to-concave up slopes developed on soft underlying rock typically display a thin, non-uniform layer of mobile regolith and are armored by debris derived from the resistant layers. Feedbacks between weathering and transport of both easily eroded rock and embedded resistant material can explain this general form where debris is dominated by large resistant blocks. In the more general case, however, relationships between the size distribution of the resistant material, relative weathering rates, and boundary condition history are not well-understood. Here we use a 1-D numerical model to explore the evolution of two end-member landforms: a hogback associated with a tilted sandstone bed, and a symmetrical ridge associated with a vertical basalt dike, both bounded by shale bedrock. The first, modeled after the Dakota Hogback near Boulder, Colorado, produces large sandstone blocks that both armor the underlying slope from weathering and stall regolith motion. The vertical dike, modeled after Shiprock, New Mexico, produces both large blocks and small basalt chips that armor the bounding slopes. We show that in both settings, feedbacks between armor and soft rock lead to autogenic processes that modulate base level signals, alter hillslope form, and increase relief over time when compared to a control case with no armor. We explore a variety of boundary conditions in which the presence of these feedbacks leads to a quasi-steady state hillslope form that differs both quantitatively and qualitatively from that expected of a traditional parabolic
Grain size controls on sediment supply from debris-mantled dryland hillslopes
Michaelides, K.
2011-12-01
characteristics, determine sediment transport dynamics and net flux, GSD supplied to the slope base and the changes in GSD on the hillslope. The results show a strong control of initial hillslope GSD on flux characteristics: (1) GSD controls the degree of non-linearity in the relationship between sediment flux and hillslope gradient. (2) Grain size uniformity controls the degree and form of non-linearity in the relationship between sediment flux and gradient. (3) Over multiple runoff events, slopes coarsen - steeper slopes become coarser than shallow slopes. For individual events, changes in GSD on the slope depend on the magnitude and duration of the runoff event and can result in variable coarsening and fining on different parts of the slope. (4) The GSD of sediment delivered to the slope base is dependent on the hillslope GSD and the hillslope attributes and runoff characteristics. For most runoff events, the GSD of fluxed sediment is finer than the hillslope GSD except for extreme runoff events on very steep slopes with intermediate GSD (not extremely coarse). These findings provide insights into hillslope responses to climatic forcing and have theoretical implications for modeling hillslope evolution in drylands.
2011-06-20
... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 11068-014--California] Orange Cove Irrigation District, and Friant Power Authority; Notice of Availability of Environmental... has prepared an Environmental Assessment (EA) regarding Orange Cove Irrigation District's and Friant...
Benchmarking NNWSI flow and transport codes: COVE 1 results
Hayden, N.K.
1985-06-01
The code verification (COVE) activity of the Nevada Nuclear Waste Storage Investigations (NNWSI) Project is the first step in certification of flow and transport codes used for NNWSI performance assessments of a geologic repository for disposing of high-level radioactive wastes. The goals of the COVE activity are (1) to demonstrate and compare the numerical accuracy and sensitivity of certain codes, (2) to identify and resolve problems in running typical NNWSI performance assessment calculations, and (3) to evaluate computer requirements for running the codes. This report describes the work done for COVE 1, the first step in benchmarking some of the codes. Isothermal calculations for the COVE 1 benchmarking have been completed using the hydrologic flow codes SAGUARO, TRUST, and GWVIP; the radionuclide transport codes FEMTRAN and TRUMP; and the coupled flow and transport code TRACR3D. This report presents the results of three cases of the benchmarking problem solved for COVE 1, a comparison of the results, questions raised regarding sensitivities to modeling techniques, and conclusions drawn regarding the status and numerical sensitivities of the codes. 30 refs
The geology of Burnsville Cove, Bath and Highland Counties, Virginia
Swezey, Christopher; Haynes, John T.; Lambert, Richard A.; White, William B.; Lucas, Philip C.; Garrity, Christopher P.
2015-01-01
Burnsville Cove is a karst region in Bath and Highland Counties of Virginia. A new geologic map of the area reveals various units of limestone, sandstone, and siliciclastic mudstone (shale) of Silurian through Devonian age, as well as structural features such as northeast-trending anticlines and synclines, minor thrust faults, and prominent joints. Quaternary features include erosional (strath) terraces and accumulations of mud, sand, and gravel. The caves of Burnsville Cove are located within predominantly carbonate strata above the Silurian Williamsport Sandstone and below the Devonian Oriskany Sandstone. Most of the caves are located within the Silurian Tonoloway Limestone, rather than the Silurian-Devonian Keyser Limestone as reported previously.
Turner, Travis L. (Inventor); Kidd, Reggie T. (Inventor); Lockard, David P (Inventor); Khorrami, Mehdi R. (Inventor); Streett, Craig L. (Inventor); Weber, Douglas Leo (Inventor)
2016-01-01
A slat cove filler is utilized to reduce airframe noise resulting from deployment of a leading edge slat of an aircraft wing. The slat cove filler is preferably made of a super elastic shape memory alloy, and the slat cove filler shifts between stowed and deployed shapes as the slat is deployed. The slat cove filler may be configured such that a separate powered actuator is not required to change the shape of the slat cove filler from its deployed shape to its stowed shape and vice-versa. The outer contour of the slat cove filler preferably follows a profile designed to maintain accelerating flow in the gap between the slat cove filler and wing leading edge to provide for noise reduction.
Soil moisture storage and hillslope stability
A. Talebi
2007-09-01
Full Text Available Recently, we presented a steady-state analytical hillslope stability model to study rain-induced shallow landslides. This model is based on kinematic wave dynamics of saturated subsurface storage and the infinite slope stability assumption. Here we apply the model to investigate the effect of neglecting the unsaturated storage on the assessment of slope stability in the steady-state hydrology. For that purpose we extend the hydrological model to compute the soil pore pressure distribution over the entire flow domain. We also apply this model for hillslopes with non-constant soil depth to compare the stability of different hillslopes and to find the critical slip surface in hillslopes with different geometric characteristics. In order to do this, we incorporate more complex approaches to compute slope stability (Janbu's non-circular method and Bishop's simplified method in the steady-state analytical hillslope stability model. We compare the safety factor (FS derived from the infinite slope stability method and the more complex approach for two cases: with and without the soil moisture profile in the unsaturated zone. We apply this extended hillslope stability model to nine characteristic hillslope types with three different profile curvatures (concave, straight, convex and three different plan shapes (convergent, parallel, divergent. Overall, we find that unsaturated zone storage does not play a critical role in determining the factor of safety for shallow and deep landslides. As a result, the effect of the unsaturated zone storage on slope stability can be neglected in the steady-state hydrology and one can assume the same bulk specific weight below and above the water table. We find that steep slopes with concave profile and convergent plan shape have the least stability. We also demonstrate that in hillslopes with non-constant soil depth (possible deep landslides, the ones with convex profiles and convergent plan shapes have
Modern sedimentation patterns in Potter Cove, King George Island, Antarctica
Hass, H. Christian; Kuhn, Gerhard; Wölfl, Anne-Cathrin; Wittenberg, Nina; Betzler, Christian
2013-04-01
IMCOAST among a number of other initiatives investigates the modern and the late Holocene environmental development of south King George Island with a strong emphasis on Maxwell Bay and its tributary fjord Potter Cove (maximum water depth: about 200 m). In this part of the project we aim at reconstructing the modern sediment distribution in the inner part of Potter Cove using an acoustic ground discrimination system (RoxAnn) and more than136 ground-truth samples. Over the past 20 years the air temperatures in the immediate working area increased by more than 0.6 K (Schloss et al. 2012) which is less than in other parts of the West Antarctic Peninsula (WAP) but it is still in the range of the recovery of temperatures from the Little Ice Age maximum to the beginning of the 20th century. Potter Cove is a small fjord characterized by a series of moraine ridges produced by a tidewater glacier (Fourcade Glacier). Presumably, the farthest moraine is not much older than about 500 years (LIA maximum), hence the sediment cover is rather thin as evidenced by high resolution seismic data. Since a few years at least the better part of the tidewater glacier retreated onto the island's mainland. It is suggested that such a fundamental change in the fjord's physiography has also changed sedimentation patterns in the area. Potter Cove is characterized by silty-clayey sediments in the deeper inner parts of the cove. Sediments are coarser (fine to coarse sands and boulders) in the shallower areas; they also coarsen from the innermost basin to the mouth of the fjord. Textural structures follow the seabed morphology, i.e. small v-shaped passages through the moraine ridges. The glacier still produces large amounts of turbid melt waters that enter the cove at various places. We presume that very fine-grained sediments fall out from the meltwater plumes and are distributed by mid-depth or even bottom currents, thus suggesting an anti-estuarine circulation pattern. Older sediments that are
Silt fences: An economical technique for measuring hillslope soil erosion
Peter R. Robichaud; Robert E. Brown
2002-01-01
Measuring hillslope erosion has historically been a costly, time-consuming practice. An easy to install low-cost technique using silt fences (geotextile fabric) and tipping bucket rain gauges to measure onsite hillslope erosion was developed and tested. Equipment requirements, installation procedures, statistical design, and analysis methods for measuring hillslope...
Excavations at Cook's Cove, Tolaga Bay, New Zealand
Walter, R.; Jacomb, C.; Brooks, E.
2011-01-01
The Cook's Cove site (Z17/311) on the East Coast of the North Island of New Zealand is an unusual example of an archaeological site spanning close to the full duration of the New Zealand prehistoric sequence. In addition to a record of Polynesian activities, the site is also well known as the type site for the North Island Holocene stratigraphy. Recent excavations at Cook's Cove have resulted in a reinterpretation of the nature of Polynesian occupation and adaptation in this part of the North Island. The application of an 'event phase' interpretative approach provides the means for reconstructing a detailed history of environmental processes and their relationships to cultural activities over a period of 700 years. (author). 61 refs., 17 figs., 13 tabs.
Soil moisture storage and hillslope stability
Talebi, A.; Uijlenhoet, R.; Troch, P.A.
2007-01-01
Recently, we presented a steady-state analytical hillslope stability model to study rain-induced shallow landslides. This model is based on kinematic wave dynamics of saturated subsurface storage and the infinite slope stability assumption. Here we apply the model to investigate the effect of
2012-06-06
....\\2\\ \\2\\ Jordan Cove states that under the LTA business model, the decision whether to utilize... that presumption ``by making an affirmative showing of inconsistency with the public interest.'' \\6\\ \\5... Cove is highlighted in Jordan Cove's application. Based on the reasoning provided in the Application...
COVE: a visual environment for ocean observatory design
Grochow, K; Lazowska, E; Stoermer, M; Kelley, D; Delaney, J
2008-01-01
Physical, chemical, and biological ocean processes play a crucial role in determining Earth's environment. Unfortunately, our knowledge of these processes is limited because oceanography is carried out today largely the way it was a century ago: as expeditionary science, going to sea in ships and measuring a relatively small number of parameters (e.g., temperature, salinity, and pressure) as time and budget allow. The NSF Ocean Observatories Initiative is a US$330 million project that will help transform oceanography from a data-poor to a data-rich science. A cornerstone of this project is the deep water Regional Scale Nodes (RSN) that will be installed off the coasts of Washington and Oregon. The RSN will include 1500 km of fiber optic cable providing power and bandwidth to the seafloor and throughout the water column. Thousands of sensors will be deployed to stream data and imagery to shore, where they will be available in real time for ocean scientists and the public at large. The design of the RSN is a complex undertaking, requiring a combination of many different interactive tools and areas of visualization: geographic visualization to see the available seafloor bathymetry, scientific visualization to examine existing geospatially located datasets, layout tools to place the sensors, and collaborative tools to communicate across the team during the design. COVE, the Common Observatory Visualization Environment, is a visualization environment designed to meet all these needs. COVE has been built by computer scientists working closely with the engineering and scientific teams who will build and use the RSN. This paper discusses the data and activities of cabled observatory design, the design of COVE, and results from its use across the team
Picturing and modelling catchments by representative hillslopes
Loritz, Ralf; Hassler, Sibylle; Jackisch, Conrad; Zehe, Erwin
2016-04-01
Hydrological modelling studies often start with a qualitative sketch of the hydrological processes of a catchment. These so-called perceptual models are often pictured as hillslopes and are generalizations displaying only the dominant and relevant processes of a catchment or hillslope. The problem with these models is that they are prone to become too much predetermined by the designer's background and experience. Moreover it is difficult to know if that picture is correct and contains enough complexity to represent the system under study. Nevertheless, because of their qualitative form, perceptual models are easy to understand and can be an excellent tool for multidisciplinary exchange between researchers with different backgrounds, helping to identify the dominant structures and processes in a catchment. In our study we explore whether a perceptual model built upon an intensive field campaign may serve as a blueprint for setting up representative hillslopes in a hydrological model to reproduce the functioning of two distinctly different catchments. We use a physically-based 2D hillslope model which has proven capable to be driven by measured soil-hydrological parameters. A key asset of our approach is that the model structure itself remains a picture of the perceptual model, which is benchmarked against a) geo-physical images of the subsurface and b) observed dynamics of discharge, distributed state variables and fluxes (soil moisture, matric potential and sap flow). Within this approach we are able to set up two behavioral model structures which allow the simulation of the most important hydrological fluxes and state variables in good accordance with available observations within the 19.4 km2 large Colpach catchment and the 4.5 km2 large Wollefsbach catchment in Luxembourg without the necessity of calibration. This corroborates, contrary to the widespread opinion, that a) lower mesoscale catchments may be modelled by representative hillslopes and b) physically
Unsteady characteristics of a slat-cove flow field
Pascioni, Kyle A.; Cattafesta, Louis N.
2018-03-01
The leading-edge slat of a multielement wing is a significant contributor to the acoustic signature of an aircraft during the approach phase of the flight path. An experimental study of the two-dimensional 30P30N geometry is undertaken to further understand the flow physics and specific noise source mechanisms. The mean statistics from particle image velocimetry (PIV) shows the differences in the flow field with angle of attack, including the interaction between the cove and trailing-edge flow. Phase-locked PIV successfully links narrow-band peaks found in the surface pressure spectrum to shear layer instabilities and also reveals that a bulk cove oscillation at a Strouhal number based on a slat chord of 0.15 exists, indicative of shear layer flapping. Unsteady surface pressure measurements are documented and used to estimate spanwise coherence length scales. A narrow-band frequency prediction scheme is also tested and found to agree well with the data. Furthermore, higher-order spectral analysis suggests that nonlinear effects cause additional peaks to arise in the power spectrum, particularly at low angles of attack.
Evolution of hillslope soils: The geomorphic theater and the geochemical play
Yoo, Kyungsoo; Weinman, Beth; Mudd, Simon Marius; Hurst, Martin; Attal, Mikael; Maher, Kate
2011-01-01
Highlights: → We ask 'how and how fast do hillslope soils form as the landscape's morphology changes over time?'. → Over wide range of denudation rates, soil thicknesses do not vary significantly. → Colluvial soils with lower denudation rates (above the knick point) are enriched in fine size fractions, Zr, and pedogenic crystalline Fe oxides. → In the two steep hillslopes below the knickpoint, no systematic topgraphic trends were found for soil geochemistry. → Soils show increasing Zr enrichment in the downslope direction only in the hillslope above the knickpoint. - Abstract: How and how fast do hillslope soils form as the landscape's morphology changes over time? Here results are shown from an ongoing study that simultaneously examines the morphologic and geochemical evolution of soil mantled hillslopes that have been exposed to distinctively different denudation history. In Northern Sierra Nevada, California, the authors are investigating a tributary basin to the Middle Fork Feather River. A major incision signal from the river is well marked in a knickpoint within the tributary basin which stretches from its mouth to the Feather River at an elevation of ∼700 m to the plateau at an elevation of ∼1500 m. Hillslopes are significantly steeper below the knickpoint. The area's total denudation rates are currently being constrained using cosmogenic radio nuclides, but a previous study suggested an order of magnitude difference in total denudation rates below and above the knickpoint. When compared with topographic attributes calculated from LIDAR data, physical erosion rates can be modeled as a linear function of ridge top curvature. Surprisingly, over the wide range of total denudation rates, soil thicknesses do not vary significantly until a threshold point where soil mantled landscapes abruptly shift to bedrock dominated landscapes. Bioturbation by tree falls appear to buffer soil thickness over the wide range of physical soil erosion rates. From
Evolution of hillslope soils: The geomorphic theater and the geochemical play
Yoo, Kyungsoo, E-mail: kyoo@umn.edu [Dept. of Soil, Water, and Climate, University of Minnesota, 439 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN, 55108-6028 (United States); Weinman, Beth [Dept. of Soil, Water, and Climate, University of Minnesota, 439 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN, 55108-6028 (United States); Mudd, Simon Marius; Hurst, Martin; Attal, Mikael [School of GeoSciences, University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, Scotland (United Kingdom); Maher, Kate [Dept. of Geological and Environmental Sciences, Braun Hall 118, 450 Serra Mall, Bldg. 320, Stanford, CA 94305-2115 (United States)
2011-06-15
Highlights: > We ask 'how and how fast do hillslope soils form as the landscape's morphology changes over time?'. > Over wide range of denudation rates, soil thicknesses do not vary significantly. > Colluvial soils with lower denudation rates (above the knick point) are enriched in fine size fractions, Zr, and pedogenic crystalline Fe oxides. > In the two steep hillslopes below the knickpoint, no systematic topgraphic trends were found for soil geochemistry. > Soils show increasing Zr enrichment in the downslope direction only in the hillslope above the knickpoint. - Abstract: How and how fast do hillslope soils form as the landscape's morphology changes over time? Here results are shown from an ongoing study that simultaneously examines the morphologic and geochemical evolution of soil mantled hillslopes that have been exposed to distinctively different denudation history. In Northern Sierra Nevada, California, the authors are investigating a tributary basin to the Middle Fork Feather River. A major incision signal from the river is well marked in a knickpoint within the tributary basin which stretches from its mouth to the Feather River at an elevation of {approx}700 m to the plateau at an elevation of {approx}1500 m. Hillslopes are significantly steeper below the knickpoint. The area's total denudation rates are currently being constrained using cosmogenic radio nuclides, but a previous study suggested an order of magnitude difference in total denudation rates below and above the knickpoint. When compared with topographic attributes calculated from LIDAR data, physical erosion rates can be modeled as a linear function of ridge top curvature. Surprisingly, over the wide range of total denudation rates, soil thicknesses do not vary significantly until a threshold point where soil mantled landscapes abruptly shift to bedrock dominated landscapes. Bioturbation by tree falls appear to buffer soil thickness over the wide range of physical soil
Hillslope processes: Mass wasting, slope stability and erosion
van Beek, R.; Cammeraat, E.; Andreu, V.; Mickovski, S.B.; Dorren, L.; Norris, J.E.; Stokes, A.; Mickovski, S.B.; Cammeraat, E.; van Beek, R.; Nicoll, B.C.; Achim, A.
2008-01-01
This chapter describes the dominant types of processes present on hillslopes where both gravity and running water are active. The impact of natural hillslope processes is important and is currently strongly influenced by human activity due to land use change and vegetation removal, and is becoming
A pilot project: Antioch Delta Cove, Antioch, California
Minder, M.
1994-01-01
The project involves the restoration of the Hickmott cannery site, comprising approximately 15 acres (three five acre parcels) located on the Delta in inter-city Antioch. Hickmott Foods, Inc., operated a fruit and vegetable cannery between 1905 and the early 1970's, during which time tomato skins, peach and apricot pits, and asparagus butts were discharged on the site. The decaying fruit pits have caused cyanide contamination. Additionally, the site contains some petroleum hydrocarbon contamination as well as gypsum board contamination, apparently from nearby manufacturing operations. The Antioch Delta Cove Pilot shows how interested parties can work together to clean up contaminated sites and use the clean up process to stimulate technology transfer. The Antioch project is a blueprint that can be replicated at other sites across California
GEOMORPHOLOGY. Experimental evidence for hillslope control of landscape scale.
Sweeney, K E; Roering, J J; Ellis, C
2015-07-03
Landscape evolution theory suggests that climate sets the scale of landscape dissection by modulating the competition between diffusive processes that sculpt convex hillslopes and advective processes that carve concave valleys. However, the link between the relative dominance of hillslope and valley transport processes and landscape scale is difficult to demonstrate in natural landscapes due to the episodic nature of erosion. Here, we report results from laboratory experiments combining diffusive and advective processes in an eroding landscape. We demonstrate that rainsplash-driven disturbances in our experiments are a robust proxy for hillslope transport, such that increasing hillslope transport efficiency decreases drainage density. Our experimental results demonstrate how the coupling of climate-driven hillslope- and valley-forming processes, such as bioturbation and runoff, dictates the scale of eroding landscapes. Copyright © 2015, American Association for the Advancement of Science.
Hillslope Discharge Analysis - Threshold Behavior and Mixing Processes
Dusek, J.; Vogel, T. N.
2017-12-01
Reliable quantitative prediction of temporal changes of both the soil water storage and the shallow subsurface runoff for natural forest hillslopes exhibiting high degree of subsurface heterogeneity remains a challenge. The intensity of stormflow determines to a large extent the residence time of water in a hillslope segment, thus also influencing biogeochemical processes and mass fluxes of nutrients. Stormflow, as one of the most important runoff mechanisms in headwater catchments, usually develops above the soil-bedrock interface during prominent rainfall-runoff events as saturated flow. In this study, one- and two-dimensional numerical models were used to analyze hydrological processes at an experimental forest site located in a small headwater catchment under humid temperate climate. The models are based on dual-continuum approach reflecting water flow and isotope transport through the soil matrix and preferential pathways. The threshold relationship between rainfall and stormflow as well as hysteresis in the hillslope stormflow-storage relationship were examined. The hillslope storage analysis was performed for selected individual rainfall-runoff events over the period of several consecutive growing seasons. Furthermore, temporal and spatial variations of pre-event and event water contributions to hillslope stormflow were evaluated using a two-component mass balance approach based on the synthetic oxygen-18 signatures. The results of this analysis showed a mutual interplay of components of hillslope water balance exposing a nonlinear character of the hillslope hydrological response. The results also suggested significant mixing processes in a hillslope segment, in particular mixing of pre-event and event water as well as water exchanged between the soil matrix and preferential pathways. Despite the dominant control of preferential stormflow on overall hillslope runoff response, a rapid and substantial contribution of pre-event water to hillslope runoff was
Deveikis, W. D.
1983-01-01
External and internal pressure and cold-wall heating-rate distributions were obtained in hypersonic flow on a full-scale heat-sink representation of the space shuttle orbiter wing-elevon-cove configuration in an effort to define effects of flow separation on cove aerothermal environment as a function of cove seal leak area, ramp angle, and free-stream unit Reynolds number. Average free-stream Mach number from all tests was 6.9; average total temperature from all tests was 3360 R; free-stream dynamic pressure ranged from about 2 to 9 psi; and wing angle of attack was 5 deg (flow compression). For transitional and turbulent flow separation, increasing cove leakage progressively increased heating rates in the cove. When ingested mass flow was sufficient to force large reductions in extent of separation, increasing cove leakage reduced heating rates in the cove to those for laminar attached flow. Cove heating-rate distributions calculated with a method that assumed laminar developing channel flow agreed with experimentally obtained distributions within root-mean-square differences that varied between 11 and 36 percent where cove walls were parallel for leak areas of 50 and 100 percent.
Subin, Z. M.; Sulman, B. N.; Malyshev, S.; Shevliakova, E.
2013-12-01
Soil moisture is a crucial control on surface energy fluxes, vegetation properties, and soil carbon cycling. Its interactions with ecosystem processes are highly nonlinear across a large range, as both drought stress and anoxia can impede vegetation and microbial growth. Earth System Models (ESMs) generally only represent an average soil-moisture state in grid cells at scales of 50-200 km, and as a result are not able to adequately represent the effects of subgrid heterogeneity in soil moisture, especially in regions with large wetland areas. We addressed this deficiency by developing the first ESM-coupled subgrid hillslope-hydrological model, TiHy (Tiled-hillslope Hydrology), embedded within the Geophysical Fluid Dynamics Laboratory (GFDL) land model. In each grid cell, one or more representative hillslope geometries are discretized into land model tiles along an upland-to-lowland gradient. These geometries represent ~1 km hillslope-scale hydrological features and allow for flexible representation of hillslope profile and plan shapes, in addition to variation of subsurface properties among or within hillslopes. Each tile (which may represent ~100 m along the hillslope) has its own surface fluxes, vegetation state, and vertically-resolved state variables for soil physics and biogeochemistry. Resolution of water state in deep layers (~200 m) down to bedrock allows for physical integration of groundwater transport with unsaturated overlying dynamics. Multiple tiles can also co-exist at the same vertical position along the hillslope, allowing the simulation of ecosystem heterogeneity due to disturbance. The hydrological model is coupled to the vertically-resolved Carbon, Organisms, Respiration, and Protection in the Soil Environment (CORPSE) model, which captures non-linearity resulting from interactions between vertically-heterogeneous soil carbon and water profiles. We present comparisons of simulated water table depth to observations. We examine sensitivities to
Tucker, G. E.; Bradley, D. N.
2008-12-01
probability distribution of displacement length is thin- tailed (approximately exponential). At high relief, hillslopes become planar, average displacement length increases by an order of magnitude, and the displacement-length distribution becomes heavy-tailed (albeit truncated at the slope length). Across the spectrum of relief values, the relationship between mean flux and gradient resembles the family of nonlinear flux-gradient curves that has been used to model hillslope evolution. We compare the emergent morphology and transport statistics with linear, nonlinear, and fractional diffusion models of hillslope transport.
Mitigating Hillslope Erosion After Post-fire Salvage Logging Operations
Robichaud, P. R.; Bone, E. D.; Brown, R. E.
2017-12-01
In the past decades, wildfires around the world have continued to increase in size, severity, and cost. Major concerns after wildfires are the increased runoff and erosion due to loss of the protective forest floor layer, loss of water storage, and creation of water repellent soil conditions. Salvage logging is often a post-fire forest management action to recoup the economic loss of the burned timber, yet concerns arise on the impacts of this activity on water quality. Recently, several studies have been conducted to determine the effect of salvage logging on hillslope erosion. Logging skid trails have been cited as being the cause of high erosion during and after salvage operations. We investigated the impacts of adding operational logging slash to skid trails to reduce hillslope erosion after salvage operations on the 2015 North Star Fire, Washington. We implemented well-designed rapid response approach to compare slash treatment effectiveness by monitoring sediment yield and runoff response from hillslopes with a concentrated flow (rill) experiment. Various runoff amounts are incrementally added to 4 m hillslope plots with and without slash treatments. Our initial results suggest that adding logging slash increased ground cover significantly which contributed to an order of magnitude decrease in hillslope erosion. Integrating erosion mitigation strategies into salvage logging operations should be commonplace when hillslope erosion is a concern.
Talebi, A.
2008-01-01
Key words: Hillslope geometry, Hillslope hydrology, Hillslope stability, Complex hillslopes, Modeling shallow landslides, HSB model, HSB-SM model.
The hydrologic response of a hillslope to rainfall involves a complex, transient saturated-unsaturated interaction that usually leads to a
Peninsula Effects on Birds in a Coastal Landscape: Are Coves More Species Rich than Lobes?
Sam Riffell
2012-10-01
Full Text Available Peninsula effects - decreasing richness with increasing distance along peninsula lobes - have been identified for many taxa on large peninsulas. Peninsula effects are caused by differences in colonization and extinction predicted by island biogeography or by environmental gradients along the peninsula. We compared species-area regressions for cove patches (i.e., mainland to regressions for lobe patches (i.e., on peninsula tips for wet meadow birds along a highly interdigitated shoreline (northern Lake Huron, USA. We conducted analysis both with and without accounting for variation in habitat and landscape characteristics (i.e., environmental gradients of wet meadows. Species-area regressions for coves did not differ from lobes, nor did these results differ when we accounted for gradients. Similarly, few species were more abundant in coves. Peninsula effects may have been lacking because lobe patches were located ≈ 800 m on average from the mainland, and birds are highly mobile and can easily sample patches over these distances. One important caveat was that wet meadow patches > 5 ha were located in coves, so coves would still be important considerations in conservation plans because of the contribution of large patches to reproductive success, dispersal and population dynamics.
Anthropogenic features and hillslope processes interaction
Tarolli, Paolo; Sofia, Giulia
2016-04-01
Topography emerges as a result of natural driving forces, but some human activities (such as mining, agricultural practices and the construction of road networks) directly or indirectly move large quantities of soil, which leave clear topographic signatures embedded on the Earth's morphology. These signatures can cause drastic changes to the geomorphological organization of the landscape, with direct consequences on Earth surface processes (Tarolli and Sofia, 2016). To this point, the present research investigates few case studies highlighting the influences of anthropogenic topographic signatures on hillslope processes, and it shows the effectiveness of High-Resolution Topography (HRT) derived from the recent remote sensing technologies (e.g. lidar, satellite, structure from motion photogrammetry), to better understand this interaction. The first example is related to agricultural terraces. In recent times, terraced areas acquired a new relevance to modern concerns about erosion and land instability, being the agricultural land mostly threatened by abandonment or intensification and specialization of agriculture, resulting in more landslide-prone bench terraces, or heavy land levelling with increased erosion. The second case study discusses about the role of agricultural and forest roads on surface erosion and landslides. The third case study investigates geomorphic processes in an open pit mine. In all case studies, HRT served as the basis for the development of new methodologies able to recognize and analyze changes on Earth surface processes along hillslopes. The results show how anthropogenic elements have crucial effects on sediment production and sediment delivery, also influencing the landscape connectivity. The availability of HRT can improve our ability to actually model anthropogenic morphologies, quantify them, and analyse the links between anthropogenic elements and geomorphic processes. The results presented here, and the creation and dissemination of
The Breakdown: Hillslope Sources of Channel Blocks in Bedrock Landscapes
Selander, B.; Anderson, S. P.; Rossi, M.
2017-12-01
Block delivery from hillslopes is a poorly understood process that influences bedrock channel incision rates and shapes steep terrain. Previous studies demonstrate that hillslope sediment delivery rate and grain size increases with channel downcutting rate or fracture density (Attal et al., 2015, ESurf). However, blocks that exceed the competence of the channel can inhibit incision. In Boulder Creek, a bedrock channel in the Colorado Front Range, large boulders (>1 m diameter) are most numerous in the steepest channel reaches; their distribution seems to reflect autogenic channel-hillslope feedback between incision rate and block delivery (Shobe et al., 2016, GRL). It is clear that the processes, rates of production, and delivery of large blocks from hillslopes into channels are critical to our understanding of steep terrain evolution. Fundamental questions are 1) whether block production or block delivery is rate limiting, 2) what mechanisms release blocks, and 3) how block production and transport affect slope morphology. As a first step, we map rock outcrops on the granodiorite hillslopes lining Boulder Creek within Boulder Canyon using a high resolution DEM. Our algorithm uses high ranges of curvature values in conjunction with slopes steeper than the angle of repose to quickly identify rock outcrops. We field verified mapped outcrop and sediment-mantled locations on hillslopes above and below the channel knickzone. We find a greater abundance of exposed rock outcrops on steeper hillslopes in Boulder Canyon. Additionally, we find that channel reaches with large in-channel blocks are located at the base of hillslopes with large areas of exposed bedrock, while reaches lacking large in-channel blocks tend to be at the base of predominately soil mantled and forested hillslopes. These observations support the model of block delivery and channel incision of Shobe et al. (2016, GRL). Moreover, these results highlight the conundrum of how rapid channel incision is
2012-09-28
... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. PF12-16-000] Dominion Cove Point LNG, LP; Notice of Intent To Prepare an Environmental Assessment for the Planned Cove Point Liquefaction Project, Request for Comments on Environmental Issues, Notice of On- Site Environmental Review, and Notice of Public Scoping Meetings The...
Aitken, Liz; Chadwick, Arthur; Hughes, Maria
2006-01-01
Centres of Vocational Excellence (CoVEs) were established in 2001, intended to be a key driver in enhancing the contribution of the further education (FE) sector to meeting skills needs. Current government policy expects employers and individuals to pay a greater share of the costs of training, particularly at Level 3, which is the CoVE priority…
2010-07-01
... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Safety and Security Zone; Cove... Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY... Areas Fifth Coast Guard District § 165.502 Safety and Security Zone; Cove Point Liquefied Natural Gas...
Low noise wing slat system with rigid cove-filled slat
Shmilovich, Arvin (Inventor); Yadlin, Yoram (Inventor)
2013-01-01
Concepts and technologies described herein provide for a low noise aircraft wing slat system. According to one aspect of the disclosure provided herein, a cove-filled wing slat is used in conjunction with a moveable panel rotatably attached to the wing slat to provide a high lift system. The moveable panel rotates upward against the rear surface of the slat during deployment of the slat, and rotates downward to bridge a gap width between the stowed slat and the lower wing surface, completing the continuous outer mold line shape of the wing, when the cove-filled slat is retracted to the stowed position.
The evolution of hillslope strength following large earthquakes
Brain, Matthew; Rosser, Nick; Tunstall, Neil
2017-04-01
Earthquake-induced landslides play an important role in the evolution of mountain landscapes. Earthquake ground shaking triggers near-instantaneous landsliding, but has also been shown to weaken hillslopes, preconditioning them for failure during subsequent seismicity and/or precipitation events. The temporal evolution of hillslope strength during and following primary seismicity, and if and how this ultimately results in failure, is poorly constrained due to the rarity of high-magnitude earthquakes and limited availability of suitable field datasets. We present results obtained from novel geotechnical laboratory tests to better constrain the mechanisms that control strength evolution in Earth materials of differing rheology. We consider how the strength of hillslope materials responds to ground-shaking events of different magnitude and if and how this persists to influence landslide activity during interseismic periods. We demonstrate the role of stress path and stress history, strain rate and foreshock and aftershock sequences in controlling the evolution of hillslope strength and stability. Critically, we show how hillslopes can be strengthened rather than weakened in some settings, challenging conventional assumptions. On the basis of our laboratory data, we consider the implications for earthquake-induced geomorphic perturbations in mountain landscapes over multiple timescales and in different seismogenic settings.
Froiland, John Mark; Smith, Liana
2014-05-01
Applied child psychologists and behavioral consultants often use systematic behavioral observations to inform the psychological assessment and intervention development process for children referred for attention and hyperactivity problems. This article provides a review of the 2010 version of the eCOVE classroom observation software in terms of its utility in tracking the progress of children with attention and hyperactive behaviors and its use in evaluating teacher behaviors that may impede or promote children's attention and positive behavior. The eCOVE shows promise as an efficient tool for psychologists and behavioral consultants who want to evaluate the effects of interventions for children with symptoms of ADHD, ODD, mood disorders and learning disorders; however, some research-based improvements for future models are suggested. The reviewers also share their firsthand experience in using eCOVE to evaluate teacher and student behavior exhibited on a television show about teaching urban high school students and during a movie about an eccentric new kindergarten teacher. Rich examples are provided of using strategic behavioral observations to reveal how to improve the classroom environment so as to facilitate attention, motivation and positive behavior among youth. Broader implications for enhancing the use of systematic behavioral observations in the assessment of children and adolescents with attention disorders and related behavioral problems are discussed. Key issues are examined such as the use of behavioral observations during psychological consultation to prevent the previously found gender bias in referrals for ADHD. Using behavioral observations to enhance differential diagnosis is also discussed.
Stock, J. D.; Rosener, M.; Schmidt, K. M.; Hanshaw, M. N.; Brooks, B. A.; Tribble, G.; Jacobi, J.
2010-12-01
Pollution from coastal watersheds threatens the ecology of the nearshore, including tropical reefs. Suspended sediment concentrations off the reefs of Molokai, Hawaii, chronically exceed a toxic 10 mg/L, threatening reef ecosystems. We hypothesize that historic conversion of hillslope processes from soil creep to overland flow increased both magnitude and frequency of erosion. To create a process sediment budget, we used surficial and ecological mapping, hillslope and stream gages, and novel sensors to locate, quantify and model the generation of fine sediments polluting the reef. Ecological and geomorphic mapping from LiDAR and multi-spectral imagery located overland flow areas with vegetation cover below a threshold preventing erosion. Here, feral goat grazing exposed volcanic soils whose low matrix hydraulic conductivities (1-25 mm/hour) promote Horton overland flow. We instrumented steep, barren hillslopes with soil moisture sensors, overland flow meters, Parshal flumes, ISCO sediment samplers, and a rain gage and conducted repeat Tripod LiDAR and infiltration tests. To characterize soil resistance to overland flow erosion, we used a Cohesive Strength Meter (CSM) to simulate water stress. At the 13.5 km 2 watershed mouth we used a USGS stream gage with an ISCO sediment sampler to estimate total load. Over 3 years, storms triggered overland flow during rainfall intensities above 10-15 mm/hr. Overland flow meters indicate such flows can be up to 3 cm deep, with a tendency to deepen downslope. CSM tests indicate that these depths are insufficient to erode soils where vegetation is dense, but far above threshold values of 2-3 mm for bare soils. Sediment ratings curves for both hillslope and downstream catchment gages show clock-wise hysteresis during the first intense storms in the fall, becoming linear later in the season. During fall storms, sediment concentration is often 10X higher at a given stage. Revised annual lowering rates from experimental hillslopes are
Sedimentary links between hillslopes and channels in a dryland basin
Hollings, R.
2016-12-01
The interface between hillslopes and channels is recognised as playing an important role in basin evolution and functioning. However, this interaction has not been described well in landscapes such as drylands, in which the diffuse process of runoff-driven sediment transport is important for sediment communication to the channel and to the basin outlet. This paper combines field measurements of surface sediment grain sizes in channels and on hillslopes with high resolution topography, >60 years of rainfall and runoff data from the Walnut Gulch Experimental Watershed (WGEW) in Arizona, and simple calculations of spatial stress distributions for various hydrologic scenarios to explore the potential for sediment to move from hillslopes to channels and through channels across the entire basin. Here we generalise the net movement of sediment in to or out of channel reaches, at high resolution in WGEW, as the balance between hillslope sediment supply to the channel and channel evacuation, in response to a variety of storms and discharge events. Our results show that downstream of small, unit source area watersheds, the balance in the channel often switches from being supply-dominated to being evacuation dominated for all scenarios. The low frequency but high discharge event in the channel seems to control the long term evolution of the channel, as stress is far greater for this scenario than other scenarios tested. The results draw on the high variability of rainfall characteristics to drive runoff events and so provides a physical explanation for long-term evolution of the channel network in drylands.
Lithologic Control on the Form of Soil Mantled Hillslopes
Johnstone, S. A.; Hilley, G. E.
2014-12-01
Slopes on steady-state soil-mantled hillslopes tend to increase downslope in a way that balances local transport capacity with the sediment supplied from progressively larger source areas. Most predictions for the transport of soil depend purely on topographic slope and constants. Thus, soil mantled topography should evolve toward smooth forms in which soils act to buffer these forms from the underlying geologic structure. However, in the Gabilan Mesa, CA, oscillations in the slope of soil-mantled hillslopes mirror oscillations in the underlying stratigraphy. Using field measurements of stratigraphy and soil depths, topographic analysis, and numerical modeling, we demonstrate that variations in rock type can impact the form of soil-mantled hillslopes. Specifically, variations in the properties of underlying rocks may yield different soil thicknesses. Balancing transport rates across these variations in thickness requires slopes to change when soil transport depends on both soil thickness and slope. A compilation of published data on the variation in activity with depth of various transport processes provides the basis for a geomorphic transport law (GTL) that generalizes the depth dependence of various transport processes. While this GTL is explicitly depth dependent, it is also capable of describing situations in which hillslope transport is relatively insensitive to variations in thickness and therefore essentially equivalent to existing formulations. We use dimensional analysis and numerical modeling to demonstrate the conditions under which transport on soil mantled slopes, and consequently topographic forms, may be sensitive to variations in soil thickness and therefore lithology.
Soil as indicator of hillslope hydrological behaviour in the ...
There is an interactive relationship between soil and hydrology. Identifying and interpreting soil properties active in this relationship can enhance our understanding of the hydrological behaviour of soils and the hillslopes in which they occur. This study was conducted in the Weatherley research catchment, South Africa, ...
Physical and chemical limnology of Ides Cove near Rochester, New York, 1970-1982
Bubeck, R.C.; Staubitz, W.W.; Weidemann, A.D.; Spittal, L.P.
1995-01-01
Ides Cove is a small embayment on the western shore of Irondequoit Bay near Rochester, N.Y. In 1982, alum was applied to the cove to seal the bottom sediments and thereby decrease nutrient fluxes in an effort to assess the applicability of this technique to Irondequoit Bay. Published data were used to develop a baseline analysis of the chemical and physical limnology of Ides Cove prior to the alum treatment and to provide a basis for comparison and evaluation of post-treatment data. The baseline analysis also enables evaluation of trends in the nutrient status and mixing patterns in Ides Cove since the decrease of sewage inflows and use of road salt in the Irondequoit Bay and Ides Cove drainage basins during 1970-82. Data from 1970-72 and 1979-82 were used to construct partial and full-year depth profiles of several physical properties and chemical constituents of water in the cove; comparison of these profiles indicates a significant improvement in water quality between 1970 and 1982. The diversion of sewage out of the Irondequoit Creek drainage basin in the late 1970's resulted in an 80-percent decrease in total phosphate concentration and a 50- to 60-percent decrease in nitrogen (nitrate and ammonia) concentration in the cove. Indications of decreased primary productivity are associated with these lowered nutrient concentrations. Summer Secchi-disk transparency increased from 0.6 m (meters) in 1970-72 to 1.2 m in 1980-82; peak epilimnetic dissolved oxygen levels decreased from a range of 22 to 28 mg/L (milligrams per liter) to a range of 16 to 20 mg/L; and peak epilimnetic pH decreased from greater than 9.4 to between 8.8 and 9.0. The decrease in the use of road salt in the Irondequoit basin beginning in 1974 resulted in a decrease in chloride concentration and gradient (difference between the surface and bottom con- centration). The maximum annual chloride concentration in the epilimnion decreased from the 210-to-225-mg/L range in the spring of 1971-72 to the
Foufoula-Georgiou, E.; Ganti, V. K.; Dietrich, W. E.
2009-12-01
Sediment transport on hillslopes can be thought of as a hopping process, where the sediment moves in a series of jumps. A wide range of processes shape the hillslopes which can move sediment to a large distance in the downslope direction, thus, resulting in a broad-tail in the probability density function (PDF) of hopping lengths. Here, we argue that such a broad-tailed distribution calls for a non-local computation of sediment flux, where the sediment flux is not only a function of local topographic quantities but is an integral flux which takes into account the upslope topographic “memory” of the point of interest. We encapsulate this non-local behavior into a simple fractional diffusive model that involves fractional (non-integer) derivatives. We present theoretical predictions from this nonlocal model and demonstrate a nonlinear dependence of sediment flux on local gradient, consistent with observations. Further, we demonstrate that the non-local model naturally eliminates the scale-dependence exhibited by any local (linear or nonlinear) sediment transport model. An extension to a 2-D framework, where the fractional derivative can be cast into a mixture of directional derivatives, is discussed together with the implications of introducing non-locality into existing landscape evolution models.
Quasi-Steady Evolution of Hillslopes in Layered Landscapes: An Analytic Approach
Glade, R. C.; Anderson, R. S.
2018-01-01
Landscapes developed in layered sedimentary or igneous rocks are common on Earth, as well as on other planets. Features such as hogbacks, exposed dikes, escarpments, and mesas exhibit resistant rock layers adjoining more erodible rock in tilted, vertical, or horizontal orientations. Hillslopes developed in the erodible rock are typically characterized by steep, linear-to-concave slopes or "ramps" mantled with material derived from the resistant layers, often in the form of large blocks. Previous work on hogbacks has shown that feedbacks between weathering and transport of the blocks and underlying soft rock can create relief over time and lead to the development of concave-up slope profiles in the absence of rilling processes. Here we employ an analytic approach, informed by numerical modeling and field data, to describe the quasi-steady state behavior of such rocky hillslopes for the full spectrum of resistant layer dip angles. We begin with a simple geometric analysis that relates structural dip to erosion rates. We then explore the mechanisms by which our numerical model of hogback evolution self-organizes to meet these geometric expectations, including adjustment of soil depth, erosion rates, and block velocities along the ramp. Analytical solutions relate easily measurable field quantities such as ramp length, slope, block size, and resistant layer dip angle to local incision rate, block velocity, and block weathering rate. These equations provide a framework for exploring the evolution of layered landscapes and pinpoint the processes for which we require a more thorough understanding to predict their evolution over time.
Tributyltin in environmental samples from the Former Derecktor Shipyard, Coddington Cove, Newport RI
Wade, Terry L.; Sweet, Stephen T.; Quinn, James G.; Cairns, Robert W.; King, John W
2004-05-01
Tributyltin (TBT) was detected in all 24 surface sediment (top 2 cm) samples collected from Coddington Cove, Newport, RI. TBT surface sediment concentrations ranged from 32 to 372 ng Sn/g with a mean concentration of 146 ng Sn/g. Analyses of selected core sections detected TBT in at least the top 18 cm at all 7 stations where cores were collected. No consistent TBT concentration trends with depth for these cores suggest mixing is an important process in the sediment column. In one core (station 28), TBT was found in the 76-86 cm section at a concentration of 141 ng Sn/g; thus sediments are a significant sink for TBT. However, sediment mixing processes can enhance releases of bioavailable TBT. Mussels, clams and fish from Coddington Cove contain TBT at concentrations ranging from 9.2 to 977 ng Sn/g. TBT concentrations in lobsters were below the detection limit (<6 ng Sn/g). Based on available screening criteria, TBT concentrations in Coddington Cove sediment is likely to be having an adverse effect on the biota at some locations. - TBT is likely to continue to be bioavailable for many years.
Tributyltin in environmental samples from the Former Derecktor Shipyard, Coddington Cove, Newport RI
Wade, Terry L.; Sweet, Stephen T.; Quinn, James G.; Cairns, Robert W.; King, John W.
2004-01-01
Tributyltin (TBT) was detected in all 24 surface sediment (top 2 cm) samples collected from Coddington Cove, Newport, RI. TBT surface sediment concentrations ranged from 32 to 372 ng Sn/g with a mean concentration of 146 ng Sn/g. Analyses of selected core sections detected TBT in at least the top 18 cm at all 7 stations where cores were collected. No consistent TBT concentration trends with depth for these cores suggest mixing is an important process in the sediment column. In one core (station 28), TBT was found in the 76-86 cm section at a concentration of 141 ng Sn/g; thus sediments are a significant sink for TBT. However, sediment mixing processes can enhance releases of bioavailable TBT. Mussels, clams and fish from Coddington Cove contain TBT at concentrations ranging from 9.2 to 977 ng Sn/g. TBT concentrations in lobsters were below the detection limit (<6 ng Sn/g). Based on available screening criteria, TBT concentrations in Coddington Cove sediment is likely to be having an adverse effect on the biota at some locations. - TBT is likely to continue to be bioavailable for many years
The Food Web of Potter Cove (Antarctica): complexity, structure and function
Marina, Tomás I.; Salinas, Vanesa; Cordone, Georgina; Campana, Gabriela; Moreira, Eugenia; Deregibus, Dolores; Torre, Luciana; Sahade, Ricardo; Tatián, Marcos; Barrera Oro, Esteban; De Troch, Marleen; Doyle, Santiago; Quartino, María Liliana; Saravia, Leonardo A.; Momo, Fernando R.
2018-01-01
Knowledge of the food web structure and complexity are central to better understand ecosystem functioning. A food-web approach includes both species and energy flows among them, providing a natural framework for characterizing species' ecological roles and the mechanisms through which biodiversity influences ecosystem dynamics. Here we present for the first time a high-resolution food web for a marine ecosystem at Potter Cove (northern Antarctic Peninsula). Eleven food web properties were analyzed in order to document network complexity, structure and topology. We found a low linkage density (3.4), connectance (0.04) and omnivory percentage (45), as well as a short path length (1.8) and a low clustering coefficient (0.08). Furthermore, relating the structure of the food web to its dynamics, an exponential degree distribution (in- and out-links) was found. This suggests that the Potter Cove food web may be vulnerable if the most connected species became locally extinct. For two of the three more connected functional groups, competition overlap graphs imply high trophic interaction between demersal fish and niche specialization according to feeding strategies in amphipods. On the other hand, the prey overlap graph shows also that multiple energy pathways of carbon flux exist across benthic and pelagic habitats in the Potter Cove ecosystem. Although alternative food sources might add robustness to the web, network properties (low linkage density, connectance and omnivory) suggest fragility and potential trophic cascade effects.
Feasibility for development of an aquaculture facility at Hot Spring Cove
1986-01-01
This report describes the feasibilty of obtaining geothermally warmed water for use in aquaculture at Hot Springs Cove, British Columbia, and concludes that while the sources can probably be assessed from two sites in the cove, neither this nor the quantity of water available can be known for certain without field trials. The report also examines the feasibility of culturing various species of sea life at Hot Springs Cove, and concludes that a combination of rearing coho salmon smolts and oysters, with the late addition of tilapia, appears to be the most suitable both for biological and economic reasons. The total capital investment amounts to about $1,033,000. Operating costs would be about $450,000 annually, and additional capital to cover this would be needed in the first years of operation. A business plan is provided which includes cash flow projections for the first nine years of operation, and this shows that a maximum investment of approximately $1.2 million would be needed by the third year of operation. If sufficient warm water is available, and the facility is operated successfully, it should pay off the investment in seven to nine years, provided that interest free loans are available for capital investments. 20 refs., 1 fig., 8 tabs.
Hillslope-channel coupling in a steep Hawaiian catchment accelerates erosion rates over 100-fold
Stock, J. D.; Hanshaw, M. N.; Rosener, M.; Schmidt, K. M.; Brooks, B. A.; Tribble, G.; Jacobi, J.
2009-12-01
In tropical watersheds, hillslope changes are producing increasing amounts of fine sediment that can be quickly carried to reefs by channels. Suspended sediment concentrations off the reefs of Molokai, Hawaii, chronically exceed a toxic level of 10 mg/L, threatening reef ecosystems. We hypothesize that historic conversion of watersheds from soil creep to overland flow erosion increased both magnitude and frequency of sediment flooding adjacent reefs. We combined surficial and ecological mapping, hillslope and stream gages, and novel sensors to locate, quantify and model the generation of fine sediments polluting the Molokai reef. Ecological and geomorphic mapping from LiDAR and multi-spectral imagery located a subset of overland flow areas with vegetation cover below a threshold value preventing erosion. Here, feral goat grazing exposed cohesive volcanic soils whose low matrix hydraulic conductivities (1-20 mm/hour) promote Horton overland flow erosion. We instrumented steep, barren hillslopes with soil moisture sensors, overland flow meters, Parshall flumes, ISCO sediment samplers, and a rain gage and conducted repeat Tripod LiDAR and infiltration tests. To characterize soil resistance here and elsewhere to overland flow erosion, we deployed a Cohesive Strength Meter (CSM) to simulate the stresses of flowing water. At the 13.5 km 2 watershed mouth we used a USGS stream gage and ISCO sediment sampler to estimate total load. Over 2 years, storms triggered overland flow during rainfall intensities above 10-15 mm/hr. Overland flow meters indicate such flows can be up to 3 cm deep, with a tendency to deepen downslope. CSM tests indicate that these depths are insufficient to erode soils where vegetation is dense, but far above threshold values of 2-3 mm depth for bare soil erosion. Sediment ratings curves for both hillslope and downstream catchment gages show strong clock-wise hysteresis during the first intense storms in the Fall, becoming linear later in the rainy
Tromp-van Meerveld, I.; McDonnell, J.
2009-05-01
We present an assessment of electromagnetic induction (EM) as a potential rapid and non-invasive method to map soil moisture patterns at the Panola (GA, USA) hillslope. We address the following questions regarding the applicability of EM measurements for hillslope hydrological investigations: (1) Can EM be used for soil moisture measurements in areas with shallow soils?; (2) Can EM represent the temporal and spatial patterns of soil moisture throughout the year?; and (3) can multiple frequencies be used to extract additional information content from the EM approach and explain the depth profile of soil moisture? We found that the apparent conductivity measured with the multi-frequency GEM-300 was linearly related to soil moisture measured with an Aqua-pro capacitance sensor below a threshold conductivity and represented the temporal patterns in soil moisture well. During spring rainfall events that wetted only the surface soil layers the apparent conductivity measurements explained the soil moisture dynamics at depth better than the surface soil moisture dynamics. All four EM frequencies (7290, 9090, 11250, and 14010 Hz) were highly correlated and linearly related to each other and could be used to predict soil moisture. This limited our ability to use the four different EM frequencies to obtain a soil moisture profile with depth. The apparent conductivity patterns represented the observed spatial soil moisture patterns well when the individually fitted relationships between measured soil moisture and apparent conductivity were used for each measurement point. However, when the same (master) relationship was used for all measurement locations, the soil moisture patterns were smoothed and did not resemble the observed soil moisture patterns very well. In addition, the range in calculated soil moisture values was reduced compared to observed soil moisture. Part of the smoothing was likely due to the much larger measurement area of the GEM-300 compared to the Aqua
Controls on hillslope stability in a mountain river catchment
Golly, Antonius; Turowski, Jens; Hovius, Niels; Badoux, Alexandre
2015-04-01
Sediment transport in fluvial systems accounts for a large fraction of natural hazard damage costs in mountainous regions and is an important factor for risk mitigation, engineering and ecology. Although sediment transport in high-gradient channels gathered research interest over the last decades, sediment dynamics in steep streams are generally not well understood. For instance, the sourcing of the sediment and when and how it is actually mobilized is largely undescribed. In the Erlenbach, a mountain torrent in the Swiss Prealps, we study the mechanistic relations between in-channel hydrology, channel morphology, external climatic controls and the surrounding sediment sources to identify relevant process domains for sediment input and their characteristic scales. Here, we analyze the motion of a slow-moving landslide complex that was permanently monitored by time-lapse cameras over a period of 70 days at a 30 minutes interval. In addition, data sets for stream discharge, air temperature and precipitation rates are available. Apparent changes in the channel morphology, e.g. the destruction of channel-spanning bed forms, were manually determined from the time-lapse images and were treated as event marks in the time series. We identify five relevant types of sediment displacement processes emerging during the hillslope motion: concentrated mud flows, deep seated hillslope failure, catastrophic cavity failure, hillslope bank erosion and individual grain loss. Generally, sediment displacement occurs on a large range of temporal and spatial scales and sediment dynamics in steep streams not only depend on large floods with long recurrence intervals. We find that each type of displacement acts in a specific temporal and spatial domain with their characteristic scales. Different external climatic forcing (e.g. high-intensity vs. long-lasting precipitation events) promote different displacement processes. Stream morphology and the presence of boulders have a large effect on
Hillslope runoff and sediment transport in south east Spain
Bracken (Nee Bull), L. J.; Kirkby, M. J.
2003-04-01
Runoff from semi-arid hillslopes in SE Spain is generated very selectively at all scales. Site response at the 1 m2 scale may be described by the dynamics of local infiltration and crusting, defining Hydrologically Similar Surfaces (HYSS), which are strongly associated with soil type and vegetation cover. This study reports the use of several reconnaissance methods to define HYSS consistently. These methods are (1) the use of small sediment traps which disturb the surface minimally,(2) the use of painted lines and (3) the identification of Morphological Zones associated with different levels of runoff and sediment transport. Five monitoring sites were established on hillslope concavities in two semi-arid catchments in South East Spain. Rainfall data were also collected from the nearest gauge established during previous research. Results show that a storm event in the Rambla de Nogalte on the 30th of June of 83.0 mm was responsible for a maximum runoff depth of 12 cm and a maximum hillslope sediment transport of 1886 cm3 m-1. The same storm in the Rambla de Torrealvilla produced 53.4 mm of rainfall on the 1st of July 2002, had a maximum runoff depth of 26 cm and was responsible for a maximum hillslope sediment transport of 2311 cm3 m-1. In general sediment transport rate and sediment travel distance increased with the distance downslope into the hillslope hollow, and these were related to the maximum depth of flow produced over the hillside. Very little sediment movement occurred directly downslope of bushes as was expected. No significant relationships were established between sediment transport and slope angle or vegetation cover. However, sediment transport and depth of runoff varied with lithology, with marl sites producing the most runoff and sediment transport. The site located on red schist was particularly unresponsive to rainfall and did not experience much sediment transport. Initial models for the response of larger areas suggest that runoff is controlled
Paulson, Anthony J.; Konrad, Christopher P.; Frans, Lonna M.; Noble, Marlene; Kendall, Carol; Josberger, Edward G.; Huffman, Raegan L.; Olsen, Theresa D.
2006-01-01
Hood Canal is a long (110 kilometers), deep (175 meters) and narrow (2 to 4 kilometers wide) fjord of Puget Sound in western Washington. The stratification of a less dense, fresh upper layer of the water column causes the cold, saltier lower layer of the water column to be isolated from the atmosphere in the late summer and autumn, which limits reaeration of the lower layer. In the upper layer of Hood Canal, the production of organic matter that settles and consumes dissolved oxygen in the lower layer appears to be limited by the load of dissolved inorganic nitrogen (DIN): nitrate, nitrite, and ammonia. Freshwater and saline loads of DIN to Hood Canal were estimated from available historical data. The freshwater load of DIN to the upper layer of Hood Canal, which could be taken up by phytoplankton, came mostly from surface and ground water from subbasins, which accounts for 92 percent of total load of DIN to the upper layer of Hood Canal. Although DIN in rain falling on land surfaces amounts to about one-half of the DIN entering Hood Canal from subbasins, rain falling directly on the surface of marine waters contributed only 4 percent of the load to the upper layer. Point-source discharges and subsurface flow from shallow shoreline septic systems contributed less than 4 percent of the DIN load to the upper layer. DIN in saline water flowing over the sill into Hood Canal from Admiralty Inlet was at least 17 times the total load to the upper layer of Hood Canal. In September and October 2004, field data were collected to estimate DIN loads to Lynch Cove - the most inland marine waters of Hood Canal that routinely contain low dissolved-oxygen waters. Based on measured streamflow and DIN concentrations, surface discharge was estimated to have contributed about one-fourth of DIN loads to the upper layer of Lynch Cove. Ground-water flow from subbasins was estimated to have contributed about one-half of total DIN loads to the upper layer. In autumn 2004, the relative
Trouble with diffusion: Reassessing hillslope erosion laws with a particle-based model
Tucker, Gregory E.; Bradley, D. Nathan
2010-03-01
Many geomorphic systems involve a broad distribution of grain motion length scales, ranging from a few particle diameters to the length of an entire hillslope or stream. Studies of analogous physical systems have revealed that such broad motion distributions can have a significant impact on macroscale dynamics and can violate the assumptions behind standard, local gradient flux laws. Here, a simple particle-based model of sediment transport on a hillslope is used to study the relationship between grain motion statistics and macroscopic landform evolution. Surface grains are dislodged by random disturbance events with probabilities and distances that depend on local microtopography. Despite its simplicity, the particle model reproduces a surprisingly broad range of slope forms, including asymmetric degrading scarps and cinder cone profiles. At low slope angles the dynamics are diffusion like, with a short-range, thin-tailed hop length distribution, a parabolic, convex upward equilibrium slope form, and a linear relationship between transport rate and gradient. As slope angle steepens, the characteristic grain motion length scale begins to approach the length of the slope, leading to planar equilibrium forms that show a strongly nonlinear correlation between transport rate and gradient. These high-probability, long-distance motions violate the locality assumption embedded in many common gradient-based geomorphic transport laws. The example of a degrading scarp illustrates the potential for grain motion dynamics to vary in space and time as topography evolves. This characteristic renders models based on independent, stationary statistics inapplicable. An accompanying analytical framework based on treating grain motion as a survival process is briefly outlined.
Ascribing soil erosion of hillslope components to river sediment yield.
Nosrati, Kazem
2017-06-01
In recent decades, soil erosion has increased in catchments of Iran. It is, therefore, necessary to understand soil erosion processes and sources in order to mitigate this problem. Geomorphic landforms play an important role in influencing water erosion. Therefore, ascribing hillslope components soil erosion to river sediment yield could be useful for soil and sediment management in order to decrease the off-site effects related to downstream sedimentation areas. The main objectives of this study were to apply radionuclide tracers and soil organic carbon to determine relative contributions of hillslope component sediment sources in two land use types (forest and crop field) by using a Bayesian-mixing model, as well as to estimate the uncertainty in sediment fingerprinting in a mountainous catchment of western Iran. In this analysis, 137 Cs, 40 K, 238 U, 226 Ra, 232 Th and soil organic carbon tracers were measured in 32 different sampling sites from four hillslope component sediment sources (summit, shoulder, backslope, and toeslope) in forested and crop fields along with six bed sediment samples at the downstream reach of the catchment. To quantify the sediment source proportions, the Bayesian mixing model was based on (1) primary sediment sources and (2) combined primary and secondary sediment sources. The results of both approaches indicated that erosion from crop field shoulder dominated the sources of river sediments. The estimated contribution of crop field shoulder for all river samples was 63.7% (32.4-79.8%) for primary sediment sources approach, and 67% (15.3%-81.7%) for the combined primary and secondary sources approach. The Bayesian mixing model, based on an optimum set of tracers, estimated that the highest contribution of soil erosion in crop field land use and shoulder-component landforms constituted the most important land-use factor. This technique could, therefore, be a useful tool for soil and sediment control management strategies. Copyright
COVE-1: a finite difference creep collapse code for oval fuel pin cladding material
Mohr, C.L.
1975-03-01
COVE-1 is a time-dependent incremental creep collapse code that estimates the change in ovality of a fuel pin cladding tube. It uses a finite difference method of solving the differential equations which describe the deflection of the tube walls as a function of time. The physical problem is nonlinear, both with respect to geometry and material properties, which requires the use of an incremental, analytical, path-dependent solution. The application of this code is intended primarily for tubes manufactured from Zircaloy. Therefore, provision has been made to include some of the effects of anisotropy in the flow equations for inelastic incremental deformations. 10 references. (U.S.)
Diatoms of the marine littoral of Steenberg's cove in St. Helena Bay, Cape province, South Africa
Malcolm, HG
1973-01-01
Full Text Available transapical striae in 10 ~m. It is easily overlooked and though recorded in the samples as infrequent may be more abundant. Dimensions of the Steenberg?s Cove material were 8?10 1zm long, 3 jzm broad, striae 27 in 10 1cm. ? 619, 620. A. proteus GREGORY... (cf. CLEVE 1895: 103; GIFFEN 1970a, 267, Fig. 19). Always rare in the material. ? 619, 620. A. proteus var. coutigna CLEVE (cf. GIFFEN 1971 a, 3). As stated in a previous paper the author doubts whether these varieties viz. var. conti,gua CLEVE...
Quantifying Hillslope to Watershed Erosional Response Following Wildfire
Vega, S.; Pierson, F. B.; Williams, C. J.; Brooks, E. S.; Strand, E. K.; Seyfried, M. S.; Murdock, M.; Pierce, J. L.; Roehner, C.; Lindsay, K.; Robichaud, P. R.; Brown, R. E.
2017-12-01
Across the western US, wildfires in sagebrush vegetation are occurring at a more frequent rate and higher severity. This has resulted in a decline of sagebrush rangeland. The changing fire regime can be attributed to invasive plant species and warming climate conditions. As the result of wildfire, protective vegetation cover is removed leaving the soil bare and exposed to erosion. Erosion following wildfire is a main concern among land managers due to the threat it poses to resources, infrastructure, and human health. Numerous studies have used artificial rainfall to assess post-fire runoff and erosion and rehabilitation treatment effectiveness. These results have found that high intensity rain events typical of summer convective storms drive post-fire erosion. The purpose of this study is to improve scientific understanding of how site-specific physical and biological attributes affect hillslope to watershed scale sediment yield on a mountainous burned sagebrush landscape. This study uses natural rainfall and a network of silt fences to quantify hillslope to watershed scale erosion response. The erosional drivers over various spatial scales were evaluated in context with vegetation recovery for a 2 year post-fire period. A network of silt fences was installed over long and short hillslope distances and in swales within the 130 ha Murphy Creek catchment in the Reynolds Creek Experimental Watershed in southwestern Idaho. We evaluated: 1) vegetation, soils, and sediment delivery across multiple spatial scales associated with 30 silt fences spanning north and south facing aspects, 2) precipitation input at two meteorological stations, and 3) watershed streamflow and sediment discharge from an existing weir. During the first and second year post-fire, the swales on both aspects produced more sediment than the short and long hillslopes. The results suggest that significant amounts of sediment and organic matter were deposited in the swales creating drifts. Sediment
Jia, Jin Tian; Fu, Zhi Yong; Chen, Hong Song; Wang, Ke Lin; Zhou, Wei Jun
2016-06-01
Based on three manually excavated trenches (projection length of 21 m, width of 1 m) along a typical Karst hillslope, the changing trends for soil-bedrock structure, average water content of soil profile and soil-bedrock interface water content along each individual trench were studied. The effect of irregular bedrock topography on soil moisture distribution was discussed. The results showed that the surface topography was inconsistent with the bedrock topography in the Karst hill-slopes. The bedrock topography was highly irregular with a maximum variation coefficient of 82%. The distribution pattern of soil profile of moisture was significantly affected by the underlying undulant bedrock. The soil water content was related to slope position when the fluctuation was gentle, and displayed a linear increase from upslope to downslope. When the bedrock fluctuation increased, the downslope linear increasing trend for soil water content became unapparent, and the spatial continuity of soil moisture was weakened. The soil moisture was converged in rock dents and cracks. The average water content of soil profile was significantly positively correlated with the soil-bedrock interface water content, while the latter responded more sensitively to the bedrock fluctuation.
Southern Appalachian hillslope erosion rates measured by soil and detrital radiocarbon in hollows
T.C. Hales; K.M. Scharer; R.M. Wooten
2012-01-01
Understanding the dynamics of sediment generation and transport on hillslopes provides important constraints on the rate of sediment output from orogenic systems. Hillslope sediment fluxes are recorded by organic material found in the deposits infilling unchanneled convergent topographic features called hollows. This study describes the first hollow infilling rates...
Hillslope threshold response to rainfall: (1) a field based forensic approach
Chris B. Graham; Ross A. Woods; Jeffrey J. McDonnell
2010-01-01
Hillslope threshold response to storm rainfall is poorly understood. Basic questions regarding the type, location, and flow dynamics of lateral, subsurface flow remain unanswered, even at our most intensively studied field sites. Here we apply a forensic approach where we combined irrigation and excavation experiments at the well studied Maimai hillslope to determine...
A sprinkling experiment to quantify celerity-velocity differences at the hillslope scale
The difference between celerity and velocity of hillslope water flow is poorly understood. We assessed these differences by combining a 24-day hillslope sprinkling experiment with a spatially explicit hydrologic model analysis. We focused our work at Watershed 10 at the H.J. And...
Effects of DTM resolution on slope steepness and soil loss prediction on hillslope profiles
Eder Paulo Moreira; William J. Elliot; Andrew T. Hudak
2011-01-01
Topographic attributes play a critical role in predicting erosion in models such as the Water Erosion Prediction Project (WEPP). The effects of four different high resolution hillslope profiles were studied using four different DTM resolutions: 1-m, 3-m, 5-m and 10-m. The WEPP model used a common scenario encountered in the forest environment and the selected hillslope...
Modeling the probability distribution of peak discharge for infiltrating hillslopes
Baiamonte, Giorgio; Singh, Vijay P.
2017-07-01
Hillslope response plays a fundamental role in the prediction of peak discharge at the basin outlet. The peak discharge for the critical duration of rainfall and its probability distribution are needed for designing urban infrastructure facilities. This study derives the probability distribution, denoted as GABS model, by coupling three models: (1) the Green-Ampt model for computing infiltration, (2) the kinematic wave model for computing discharge hydrograph from the hillslope, and (3) the intensity-duration-frequency (IDF) model for computing design rainfall intensity. The Hortonian mechanism for runoff generation is employed for computing the surface runoff hydrograph. Since the antecedent soil moisture condition (ASMC) significantly affects the rate of infiltration, its effect on the probability distribution of peak discharge is investigated. Application to a watershed in Sicily, Italy, shows that with the increase of probability, the expected effect of ASMC to increase the maximum discharge diminishes. Only for low values of probability, the critical duration of rainfall is influenced by ASMC, whereas its effect on the peak discharge seems to be less for any probability. For a set of parameters, the derived probability distribution of peak discharge seems to be fitted by the gamma distribution well. Finally, an application to a small watershed, with the aim to test the possibility to arrange in advance the rational runoff coefficient tables to be used for the rational method, and a comparison between peak discharges obtained by the GABS model with those measured in an experimental flume for a loamy-sand soil were carried out.
Cycling of beryllium and carbon through hillslope soils in Iowa
Harden, J.W.; Fries, T.L.; Pavich, M.J.
2002-01-01
Isotopes of Be and C were used to reconstruct loess accumulation, hillslope evolution, and agricultural modification in soils of western Iowa. While both elements are derived from additions by the atmosphere (via plants in the case of carbon), the differences in element cycling allow erosional and depositional processes to be separated from biochemical processing. Based on 10Be, loess accumulation likely occurred simultaneously with hillslope degradation. Rates of loess accumulation declined five-fold between early stages (late Pleistocene and early Holocene) and later stages (late Holocene) of accumulation, but the absolute timing of accumulation requires independent dating methods. Based on 14C measurements, plant inputs and decomposition are significant near the surface, but below 1-1.5 m carbon inputs are minimal and decomposition is nearly arrested. The amount of carbon below 1.5 m is constant (0.1%) and is composed of soil organic matter that was buried by loess. Agricultural modification results in a dramatic redistribution of 10Be through soil erosion and deposition. By contrast, the redistribution of soil organic matter is masked by the rapid cycling of C through the topsoil as it continually decomposes and is replaced by plant inputs.
Sheibley, Rich W.; Josberger, Edward G.; Chickadel, Chris
2010-01-01
The input of freshwater and associated nutrients into Lynch Cove and lower Hood Canal (fig. 1) from sources such as groundwater seeps, small streams, and ephemeral creeks may play a major role in the nutrient loading and hydrodynamics of this low dissolved-oxygen (hypoxic) system. These disbursed sources exhibit a high degree of spatial variability. However, few in-situ measurements of groundwater seepage rates and nutrient concentrations are available and thus may not represent adequately the large spatial variability of groundwater discharge in the area. As a result, our understanding of these processes and their effect on hypoxic conditions in Hood Canal is limited. To determine the spatial variability and relative intensity of these sources, the U.S. Geological Survey Washington Water Science Center collaborated with the University of Washington Applied Physics Laboratory to obtain thermal infrared (TIR) images of the nearshore and intertidal regions of Lynch Cove at or near low tide. In the summer, cool freshwater discharges from seeps and streams, flows across the exposed, sun-warmed beach, and out on the warm surface of the marine water. These temperature differences are readily apparent in aerial thermal infrared imagery that we acquired during the summers of 2008 and 2009. When combined with co-incident video camera images, these temperature differences allow identification of the location, the type, and the relative intensity of the sources.
Dykhuizen, R.C.; Barnard, R.W.
1992-02-01
The Nuclear Waste Repository Technology Department at Sandia National Laboratories (SNL) is investigating the suitability of Yucca Mountain as a potential site for underground burial of nuclear wastes. One element of the investigations is to assess the potential long-term effects of groundwater flow on the integrity of a potential repository. A number of computer codes are being used to model groundwater flow through geologic media in which the potential repository would be located. These codes compute numerical solutions for problems that are usually analytically intractable. Consequently, independent confirmation of the correctness of the solution is often not possible. Code verification is a process that permits the determination of the numerical accuracy of codes by comparing the results of several numerical solutions for the same problem. The international nuclear waste research community uses benchmarking for intercomparisons that partially satisfy the Nuclear Regulatory Commission (NRC) definition of code verification. This report presents the results from the COVE-2A (Code Verification) project, which is a subset of the COVE project
Novelli, P.C. (SUNY, Stony Brook, NY (USA) Univ. of Colorado, Boulder (USA)); Michelson, A.R.; Scranton, M.I. (SUNY, Stony Brook, NY (USA)); Banta, G.T.; Hobbie, J.E. (Marine Biological Laboratory, Woods, Hole, MA (USA)); Howarth, R.W. (Cornell Univ., Ithaca, NY (USA))
1988-10-01
Molecular hydrogen and acetate are believed to be key intermediates in the anaerobic remineralization of organic carbon. The authors have made measurements of the cycling of both these compounds in two marine sediments: the bioturbated sediments of Buzzards Bay, Mass., and the much more reducing sediments of Town Cove, Orleans, Mass. Hydrogen concentrations are similar in these environments (from less than 5 to 30 nM), and are within the range previously reported for coastal sediments. However, apparent hydrogen production rates differ by a factor of 60 between these two sediments and at both sites show strong correlation with measured rates of sulfate reduction. Acetate concentrations generally increased with depth in both environments; this increase was greater in Buzzards Bay (22.5 to 71.5 {mu}M) than in Town Cove (26 to 44 {mu}M). Acetate oxidation rates calculated from measured concentrations and {sup 14}C-acetate consumption rate constants suggest that the measured acetate was not all available to sulfate-reducing bacteria. Using the measured sulfate reduction rates, they estimate that between 2% and 100% of the measured acetate pool is biologically available, and that the bioavailable pool decreases with depth. A diagenetic model of the total acetate concentration suggests that consumption may be first order with respect to only a fraction of the total pool.
SOSlope: a new slope stability model for vegetated hillslopes
Cohen, D.; Schwarz, M.
2016-12-01
Roots contribute to increase soil strength but forces mobilized by roots depend on soil relative displacement. This effect is not included in models of slope stability. Here we present a new numerical model of shallow landslides for vegetated hillslopes that uses a strain-step loading approach for force redistributions within a soil mass including the effects of root strength in both tension and compression. The hillslope is discretized into a two-dimensional array of blocks connected by bonds. During a rainfall event the blocks's mass increases and the soil shear strength decreases. At each time step, we compute a factor of safety for each block. If the factor of safety of one or more blocks is less than one, those blocks are moved in the direction of the local active force by a predefined amount and the factor of safety is recalculated for all blocks. Because of the relative motion between blocks that have moved and those that remain stationary, mechanical bond forces between blocks that depend on relative displacement change, modifying the force balance. This relative motion triggers instantaneous force redistributions across the entire hillslope similar to a self-organized critical system. Looping over blocks and moving those that are unstable is repeated until all blocks are stable and the system reaches a new equilibrium, or, some blocks have failed causing a landslide. Spatial heterogeneity of vegetation is included by computing the root density and distribution as a function of distance form trees. A simple subsurface hydrological model based on dual permeability concepts is used to compute the temporal evolution of water content, pore-water pressure, suction stress, and soil shear strength. Simulations for a conceptual slope indicates that forces mobilized in tension and compression both contribute to the stability of the slope. However, the maximum tensional and compressional forces imparted by roots do not contribute simultaneously to the stability of
Conceptualization of preferential flow for hillslope stability assessment
Kukemilks, Karlis; Wagner, Jean-Frank; Saks, Tomas; Brunner, Philip
2018-03-01
This study uses two approaches to conceptualize preferential flow with the goal to investigate their influence on hillslope stability. Synthetic three-dimensional hydrogeological models using dual-permeability and discrete-fracture conceptualization were subsequently integrated into slope stability simulations. The slope stability simulations reveal significant differences in slope stability depending on the preferential flow conceptualization applied, despite similar small-scale hydrogeological responses of the system. This can be explained by a local-scale increase of pore-water pressures observed in the scenario with discrete fractures. The study illustrates the critical importance of correctly conceptualizing preferential flow for slope stability simulations. It further demonstrates that the combination of the latest generation of physically based hydrogeological models with slope stability simulations allows for improvement to current modeling approaches through more complex consideration of preferential flow paths.
Wehrs, K.; Crosby, B. T.
2017-12-01
River response to changes in climate and relative base level often leave behind a legacy of transient landforms that enable the interpretation of past events. The dominant paradigm is that base level fall initiates a wave of mainstem incision that progressively transmits change upstream. Mainstem-adjacent hillslopes coupled to the channel subsequently respond as their toe slopes are steepened. To test this paradigm, we first use a longitudinal set of mainstem terrace ages to evaluate whether incision incrementally progresses upstream or is contemporaneous. Second, we explore longitudinal variations in mainstem-adjacent mass movements to evaluate whether they reflect a time and space progression in response. The South Fork Eel River in northern California contains over 600 mainstem-adjacent mass movements and 60 m tall, longitudinally extensive strath terraces that record a landscape response to river incision. We use Optically Stimulated Luminescence, with feldspars and coarse-grained sampling technique, to determine the depositional age of alluvial fill atop the strath terrace. If terrace abandonment progressively young upstream, this suggests that base level fall was not spatially contemporaneous, but rather time progressive. As a consequence, the age, form, and extent of mass wasting events should also vary longitudinally. Because terraces isolate hillslopes from the base level fall signal, we use these surfaces to quantify hillslope form and function independent of that forcing. Preliminary results using mainstem-parallel, 1 m LiDAR, show significant variation in size of mass movements throughout the basin, with planar, linearly moving translational landslides dominating throughout the catchment. In the lower basin, well downstream of the current knickzone, we see an increase in mass movement concentration, reactivation, and overall extent of mass movements. Multiple factors confound our interpretation of hillslope morphology and response, due to changes in
Lee, K.; Wohlgeschaffen, G. D.; Tremblay, G. H. [Dept. of Fisheries and Oceans of Canada, Inst. Maurice-Lamontagne, Mont Joli, PQ (Canada); Vandermeulen, D. C.; Mossman, K. G. [Dept. of Fisheries and Oceans of Canada, Bedford Inst. of Oceanography, Dartmouth, NS (Canada); Doe, K. G.; Jackman, P. M. [Environment Canada, Environmental Science Center, Moncton, NB (Canada); Prince, R. C.; Garrett, R. M.; Haith, C. E. [Exxon Research and Engineering Company, Annandale, NJ (United States)
1998-12-31
In 1970, approximately 2,045 cubic metres of Bunker C oil impacted on 300 km of Nova Scotia`s coastline following the grounding of the tanker `Arrow`. Only 10 per cent of the coastline was subjected to cleanup, the remainder was left to degrade naturally. Samples of sediments were collected in 1993 and 1997 in order to assess the attenuation processes on the reduction of toxicity within sediments and interstitial waters at Black Duck Cove, one of the untreated sites where residual oil was clearly evident. Detailed chemical analyses showed that the Bunker C oil at this site has undergone substantial biodegradation. Over the 20 plus years since the oil spill the toxicity of the residual oil has been significantly reduced and there is substantial evidence of habitat recovery.
Lee, K.; Wohlgeschaffen, G. D.; Tremblay, G. H. [Dept. of Fisheries and Oceans of Canada, Inst. Maurice-Lamontagne, Mont Joli, PQ (Canada); Vandermeulen, D. C.; Mossman, K. G. [Dept. of Fisheries and Oceans of Canada, Bedford Inst. of Oceanography, Dartmouth, NS (Canada); Doe, K. G.; Jackman, P. M. [Environment Canada, Environmental Science Center, Moncton, NB (Canada); Prince, R. C.; Garrett, R. M.; Haith, C. E. [Exxon Research and Engineering Company, Annandale, NJ (United States)
1998-07-01
In 1970, approximately 2,045 cubic metres of Bunker C oil impacted on 300 km of Nova Scotia's coastline following the grounding of the tanker 'Arrow'. Only 10 per cent of the coastline was subjected to cleanup, the remainder was left to degrade naturally. Samples of sediments were collected in 1993 and 1997 in order to assess the attenuation processes on the reduction of toxicity within sediments and interstitial waters at Black Duck Cove, one of the untreated sites where residual oil was clearly evident. Detailed chemical analyses showed that the Bunker C oil at this site has undergone substantial biodegradation. Over the 20 plus years since the oil spill the toxicity of the residual oil has been significantly reduced and there is substantial evidence of habitat recovery.
Zorzi, Alessandro; Leoni, Loira; Di Paolo, Fernando M; Rigato, Ilaria; Migliore, Federico; Bauce, Barbara; Pelliccia, Antonio; Corrado, Domenico
2015-02-15
Early repolarization (ER) is typically observed in highly trained athletes as a physiologic consequence of increased vagal tone. The variant of anterior (V1 to V3) ER characterized by "domed" ST-segment elevation and negative T wave raises problems of differential diagnosis with the "coved-type" electrocardiographic pattern seen in Brugada syndrome (BS). This study was designed to identify electrocardiographic criteria for distinguishing athlete's ER from BS. The study compared the electrocardiographic tracings of 61 healthy athletes (80% men, median age 23 ± 8 years), showing "domed" ST-segment elevation and negative T wave in leads V1 to V3, with those of 92 consecutive age- and sex-matched BS patients with a "coved-type" electrocardiographic pattern. The electrocardiographic analysis focused on the ST-segment elevation at J point (STJ) and at 80 milliseconds after J point (ST₈₀). Athletes had a lower maximum amplitude of STJ (1.46 ± 0.7 vs 3.25 ± 0.6 mm, p 1) versus only 2 (3%) athletes (p <0.001). An upsloping ST-segment configuration (STJ/ST₈₀ <1) showed a sensitivity of 97%, a specificity of 100%, and a diagnostic accuracy of 98.7% for the diagnosis of ER. At multivariate analysis, STJ/ST₈₀ ratio remained the only independent predictor for ER (odds ratio 87, 95% confidence interval 19 to 357, p <0.001). In conclusion, the STJ/ST₈₀ ratio is a highly accurate electrocardiographic parameter for differential diagnosis between anterior ER of the athlete and BS. Our results may help in reducing the number of athletes who undergo expensive diagnostic workup or are unnecessarily disqualified from competition for changes that fall within the normal range of athlete's heart. Copyright © 2015 Elsevier Inc. All rights reserved.
Mudd, S. M.; Yoo, K.; Hurst, M. D.; Weinman, B. A.; Maher, K.
2011-12-01
Landscapes evolve through time, both in terms of their geomorphology and their geochemistry. Past studies have highlighted that topography suffers from the problem of equifinality: the topographic configuration of landscapes can be the result of many different, yet equally plausible, erosion histories. In hillslope soils the properties and chemistry of the soils themselves could provide additional constraints on landscape evolution. Here we present results from a combination of modelling and field studies that seek to quantify the co-evolution of hillslope morphology and the solid state chemistry of hillslope soils. The models follow large numbers of individual particles as they are entrained into a physically mobile soil layer, weathered, and accumulate isotopes such as 10Be and 21Ne. We demonstrate that multiple hillslope properties mitigate (but do not eliminate) the problem of equifinality and demonstrate the importance of accounting for individual particle residence times and ages in interpretation of both isotope and weathering data.
Curvature distribution within hillslopes and catchments and its effect on the hydrological response
Bogaart, P.W.; Troch, P.A.A.
2006-01-01
Topographic convergence and divergence are first order controls on the hillslope and catchment hydrological response, as evidenced by similarity parameter analyses. Hydrological models often do not take convergence as measured by contour curvature directly into account; instead they use comparable
The problem of predicting the size distribution of sediment supplied by hillslopes to rivers
Sklar, Leonard S.; Riebe, Clifford S.; Marshall, Jill A.; Genetti, Jennifer; Leclere, Shirin; Lukens, Claire L.; Merces, Viviane
2017-01-01
Sediments link hillslopes to river channels. The size of sediments entering channels is a key control on river morphodynamics across a range of scales, from channel response to human land use to landscape response to changes in tectonic and climatic forcing. However, very little is known about what controls the size distribution of particles eroded from bedrock on hillslopes, and how particle sizes evolve before sediments are delivered to channels. Here we take the first steps toward building a geomorphic transport law to predict the size distribution of particles produced on hillslopes and supplied to channels. We begin by identifying independent variables that can be used to quantify the influence of five key boundary conditions: lithology, climate, life, erosion rate, and topography, which together determine the suite of geomorphic processes that produce and transport sediments on hillslopes. We then consider the physical and chemical mechanisms that determine the initial size distribution of rock fragments supplied to the hillslope weathering system, and the duration and intensity of weathering experienced by particles on their journey from bedrock to the channel. We propose a simple modeling framework with two components. First, the initial rock fragment sizes are set by the distribution of spacing between fractures in unweathered rock, which is influenced by stresses encountered by rock during exhumation and by rock resistance to fracture propagation. That initial size distribution is then transformed by a weathering function that captures the influence of climate and mineralogy on chemical weathering potential, and the influence of erosion rate and soil depth on residence time and the extent of particle size reduction. Model applications illustrate how spatial variation in weathering regime can lead to bimodal size distributions and downstream fining of channel sediment by down-valley fining of hillslope sediment supply, two examples of hillslope control on
Soil erosion assessment on hillslope of GCE using RUSLE model
Islam, Md. Rabiul; Jaafar, Wan Zurina Wan; Hin, Lai Sai; Osman, Normaniza; Din, Moktar Aziz Mohd; Zuki, Fathiah Mohamed; Srivastava, Prashant; Islam, Tanvir; Adham, Md. Ibrahim
2018-06-01
A new method for obtaining the C factor (i.e., vegetation cover and management factor) of the RUSLE model is proposed. The method focuses on the derivation of the C factor based on the vegetation density to obtain a more reliable erosion prediction. Soil erosion that occurs on the hillslope along the highway is one of the major problems in Malaysia, which is exposed to a relatively high amount of annual rainfall due to the two different monsoon seasons. As vegetation cover is one of the important factors in the RUSLE model, a new method that accounts for a vegetation density is proposed in this study. A hillslope near the Guthrie Corridor Expressway (GCE), Malaysia, is chosen as an experimental site whereby eight square plots with the size of 8× 8 and 5× 5 m are set up. A vegetation density available on these plots is measured by analyzing the taken image followed by linking the C factor with the measured vegetation density using several established formulas. Finally, erosion prediction is computed based on the RUSLE model in the Geographical Information System (GIS) platform. The C factor obtained by the proposed method is compared with that of the soil erosion guideline Malaysia, thereby predicted erosion is determined by both the C values. Result shows that the C value from the proposed method varies from 0.0162 to 0.125, which is lower compared to the C value from the soil erosion guideline, i.e., 0.8. Meanwhile predicted erosion computed from the proposed C value is between 0.410 and 3.925 t ha^{-1 } yr^{-1} compared to 9.367 to 34.496 t ha^{-1} yr^{-1 } range based on the C value of 0.8. It can be concluded that the proposed method of obtaining a reasonable C value is acceptable as the computed predicted erosion is found to be classified as a very low zone, i.e. less than 10 t ha^{-1 } yr^{-1} whereas the predicted erosion based on the guideline has classified the study area as a low zone of erosion, i.e., between 10 and 50 t ha^{-1 } yr^{-1}.
Rimondino, Clara; Torre, Luciana; Sahade, Ricardo Jose; Tatian, Marcos
2016-01-01
The muddy bottoms of inner Potter Cove, King George Island (Isla 25 de Mayo), South Shetlands, Antarctica, show a high density and richness of macrobenthic species, particularly ascidians. In other areas, ascidians have been reported to play the role of ecosystem engineers, as they support a significant number of epibionts, increasing benthic diversity. In this study, a total of 21 sessile macro-epibiotic taxa present on the ascidian species Corella antarctica Sluiter, 1905, Cnemidocarpa verr...
Hydrological Modelling Using a Rainfall Simulator over an Experimental Hillslope Plot
Arpit Chouksey
2017-03-01
Full Text Available Hydrological processes are complex to compute in hilly areas when compared to plain areas. The governing processes behind runoff generation on hillslopes are subsurface storm flow, saturation excess flow, overland flow, return flow and pipe storage. The simulations of the above processes in the soil matrix require detailed hillslope hydrological modelling. In the present study, a hillslope experimental plot has been designed to study the runoff generation processes on the plot scale. The setup is designed keeping in view the natural hillslope conditions prevailing in the Northwestern Himalayas, India where high intensity rainfall events occur frequently. A rainfall simulator was installed over the experimental hillslope plot to generate rainfall with an intensity of 100 mm/h, which represents the dominating rainfall intensity range in the region. Soil moisture sensors were also installed at variable depths from 100 to 1000 mm at different locations of the plot to observe the soil moisture regime. From the experimental observations it was found that once the soil is saturated, it remains at field capacity for the next 24–36 h. Such antecedent moisture conditions are most favorable for the generation of rapid stormflow from hillslopes. A dye infiltration test was performed on the undisturbed soil column to observe the macropore fraction variability over the vegetated hillslopes. The estimated macropore fractions are used as essential input for the hillslope hydrological model. The main objective of the present study was to develop and test a method for estimating runoff responses from natural rainfall over hillslopes of the Northwestern Himalayas using a portable rainfall simulator. Using the experimental data and the developed conceptual model, the overland flow and the subsurface flow through a macropore-dominated area have been estimated/analyzed. The surface and subsurface runoff estimated using the developed hillslope hydrological model
Formation of runoff at the hillslope scale during intense precipitation
S. Scherrer
2007-01-01
Full Text Available On 60 m2 hillslope plots, at 18 mainly grassland locations in Switzerland rain was applied at rates of 50–100 mm/h for between 3 and 6 h. The generated flows were measured, including overland flow, near surface and subsurface flow 0.5–1.3 m below the surface. At some locations less than 2% of the rain flowed down the slope either on or below the surface, whereas at some others more than 90% of the rain ran off. At the majority of sites most runoff was overland flow, though at a few sites subsurface flow, usually via macropores was dominant. Data collected during each of 48 high intensity sprinkling experiments were used to distinguish, which processes were dominant in each experiment. Which dominant and subsidiary processes occurred depended on interactions between infiltration rate, change in soil water storage and drainage of the soil water. These attributes were often not directly linked to parameters usually considered important like vegetation, slope, soil clay content and antecedent soil moisture. Considering the structure of the soil in combination with these attributes, process determination was in many cases fairly straightforward, indicating the possibility of reliably predicting runoff processes at a site. However, at some sites, effects occurred that were not easily recognizable and led to surprising results.
The Ecohydrologic Role of Coexistence and Competition in Semiarid Hillslopes
Soltanjalili, M. J.; Saco, P. M.; Willgoose, G. R.
2015-12-01
Through its influence on runoff and erosion-deposition processes, vegetation remarkably regulates different aspects of landscape dynamics. Here, the influence of different plant functional traits on the coexistence of different species in arid and semi-arid regions with patchy vegetation is investigated using an ecohydrology model. The model simulates coevolving changes in biomass patterns for two species, as well as overland flow and soil moisture dynamics. Vegetation patterns emerge as a result of facilitation (shading and infiltration) and competition mechanisms as well as varying seed dispersal strategies. The results show that the survival of only one species or the coexistence of both species not only strongly depends on environmental stresses, but also on differences in hillslope micro and macro topography. These vegetation patterns have very different hydrologic signatures and the potential to trigger remarkably different geomorphic responses. Based on these results we establish new hypothesis that will be used to further investigate the role of plant interspecific and intraspecific feedbacks on landscape coevolution processes.
Rainfall Simulator Experiments to Investigate Macropore Impacts on Hillslope Hydrological Response
Yvonne Smit
2016-11-01
Full Text Available Understanding hillslope runoff response to intense rainfall is an important topic in hydrology, and is key to correct prediction of extreme stream flow, erosion and landslides. Although it is known that preferential flow processes activated by macropores are an important phenomena in understanding runoff processes inside a hillslope, hydrological models have generally not embraced the concept of an extra parameter that represents ‘macropores’ because of the complexity of the phenomenon. Therefore, it is relevant to investigate the influence of macropores on runoff processes in an experimental small artificial hillslope. Here, we report on a controlled experiment where we could isolate the influence of macropores without the need for assumptions regarding their characteristics. Two identical hillslopes were designed, of which one was filled with artificial macropores. Twelve artificial rainfall events were applied to the two hillslopes and results of drainage and soil moisture were investigated. After the experiments, it could be concluded that the influence of macropores on runoff processes was minimal. The S90 sand used for this research caused runoff to respond fast to rainfall, leading to little or no development of saturation near the macropores. In addition, soil moisture data showed a large amount of pendular water in the hillslopes, which implies that the soil has a low air entry value, and, in combination with the lack of vertical flow, could have caused the pressure difference between the matrix and the macropores to vanish sooner and result in equilibrium being reached in a relatively short time. Nevertheless, a better outline is given to determine a correct sand type for these types of experiments and, by using drainage recession analysis to investigate the influences of macropores on runoff, heterogeneity in rainfall intensity can be overcome. This study is a good point of reference to start future experiments from concerning
New insight into unstable hillslopes hydrology from hydrogeochemical modelling.
Bertrand, C.; Marc, V.; Malet, J.-P.
2010-05-01
In the black marl outcrops of the French South Alps, sub surface flow conditions are considered as the main triggering factor for initiation and reactivation of landslides. The problem is traditionally addressed in term of hydrological processes (how does percolation to the water table occur?) but in some cases the origin of water is also in question. Direct rainfall is generally assumed as the only water source for groundwater recharge in shallow hillslope aquifers. The bedrock is also supposed impervious and continuous. Yet the geological environment of the study area is very complex owing to the geological history of this alpine sector. The autochthonous callovo-oxfordian black marl bedrock is highly tectonized (Maquaire et al., 2003) and may be affected by large, possibly draining discontinuities. A deep water inflow at the slip surface may at least locally result in increase the pore pressure and decrease the effective shearing resistance of the landslide material. In the active slow-moving landslide of Super-Sauze (Malet and Maquaire, 2003), this question has been addressed using hydrochemical investigations. The groundwater was sampled during five field campaigns uniformly spread out over the year from a network of boreholes. Water chemistry data were completed by geochemical and mineralogical analyses of the marl material. The major hydro-geochemical processes over area proved (1) mixing processes, (2) pyrite alteration, (3) dissolution/precipitation of carbonates and (4) cations exchange (de Montety et al., 2007). A geochemical modelling was carried out using the model Phreeqc (Parkhurst and Appelo, version 2.15, 2008) to check how suitable was observed water chemistry with the reservoir characteristics. The modelling exercise was based on a kinetics approach of soil-water interactions. The model simulates the rock alteration by the dissolution of the primary minerals and the precipitation of new phases. Initial parameters were obtained from geochemical
Pressure-Velocity Correlations in the Cove of a Leading Edge Slat
Wilkins, Stephen; Richard, Patrick; Hall, Joseph
2015-11-01
One of the major sources of aircraft airframe noise is related to the deployment of high-lift devices, such as leading-edge slats, particularly when the aircraft is preparing to land. As the engines are throttled back, the noise produced by the airframe itself is of great concern, as the aircraft is low enough for the noise to impact civilian populations. In order to reduce the aeroacoustic noise sources associated with these high lift devices for the next generation of aircraft an experimental investigation of the correlation between multi-point surface-mounted fluctuating pressures measured via flush-mounted microphones and the simultaneously measured two-component velocity field measured via Particle Image Velocimetry (PIV) is studied. The development of the resulting shear-layer within the slat cove is studied for Re =80,000, based on the wing chord. For low Mach number flows in air, the major acoustic source is a dipole acoustic source tied to fluctuating surface pressures on solid boundaries, such as the underside of the slat itself. Regions of high correlations between the pressure and velocity field near the surface will likely indicate a strong acoustic dipole source. In order to study the underlying physical mechanisms and understand their role in the development of aeroacoustic noise, Proper Orthogonal Decomposition (POD) by the method of snapshots is employed on the velocity field. The correlation between low-order reconstructions and the surface-pressure measurements are also studied.
Land use and surface process domains on alpine hillslopes
Kuhn, Nikolaus J.; Caviezel, Chatrina; Hunziker, Matthias
2015-04-01
Shrubs and trees are generally considered to protect hillslopes from erosion. As a consequence, shrub encroachment on mountain pastures after abandoning grazing is not considered a threat to soils. However, the abandonment of mown or grazed grasslands causes a shift in vegetation composition and thus a change in landscape ecology and geomorphology. On many alpine slopes, current changes in land use and vegetation cover are accompanied by climate change, potentially generating a new geomorphic regime. Most of the debate focuses on the effect of land abandonment on water erosion rates. Generally, an established perennial vegetation cover improves the mechanical anchoring of the soil and the regulation of the soil water budget, including runoff generation and erosion. However, changing vegetation composition affects many other above- and below-ground properties like root density, -diversity and -geometry, soil structure, pore volume and acidity. Each combination of these properties can lead to a distinct scenario of dominating surface processes, often not reflected by common erosion risk assessment procedures. The study of soil properties along a chronosequence of green alder (alnusviridis) encroachment on the Unteralptal in central Switzerland reveals that shrub encroachment changes soil and vegetation properties towards an increase of resistance to run-off related erosion processes, but a decrease of slope stability against shallow landslides. The latter are a particular threat because of the currently increasing frequency of slide-triggering high magnitude rainfalls. The potential change of process domain on alpine pastures highlights the need for a careful use of erosion models when assessing future land use and climate scenarios. In mountains, but also other intensively managed agricultural landscapes, risk assessment without the appropriate reflection on the shifting relevance of surface processes carries the risk of missing future threats to environmental
Wang, Jie; Chen, Li; Yu, Zhongbo
2018-02-01
Rainfall infiltration on hillslopes is an important issue in hydrology, which is related to many environmental problems, such as flood, soil erosion, and nutrient and contaminant transport. This study aimed to improve the quantification of infiltration on hillslopes under both steady and unsteady rainfalls. Starting from Darcy's law, an analytical integral infiltrability equation was derived for hillslope infiltration by use of the flux-concentration relation. Based on this equation, a simple scaling relation linking the infiltration times on hillslopes and horizontal planes was obtained which is applicable for both small and large times and can be used to simplify the solution procedure of hillslope infiltration. The infiltrability equation also improved the estimation of ponding time for infiltration under rainfall conditions. For infiltration after ponding, the time compression approximation (TCA) was applied together with the infiltrability equation. To improve the computational efficiency, the analytical integral infiltrability equation was approximated with a two-term power-like function by nonlinear regression. Procedures of applying this approach to both steady and unsteady rainfall conditions were proposed. To evaluate the performance of the new approach, it was compared with the Green-Ampt model for sloping surfaces by Chen and Young (2006) and Richards' equation. The proposed model outperformed the sloping Green-Ampt, and both ponding time and infiltration predictions agreed well with the solutions of Richards' equation for various soil textures, slope angles, initial water contents, and rainfall intensities for both steady and unsteady rainfalls.
Use of rare earth oxides as tracers to identify sediment source areas for agricultural hillslopes
C. Deasy
2010-11-01
Full Text Available Understanding sediment sources is essential to enable more effective targeting of in-field mitigation approaches to reduce diffuse pollution from agricultural land. In this paper we report on the application of rare earth element oxides to arable soils at hillslope scale in order to determine sediment source areas and their relative importance, using a non-intrusive method of surface spraying. Runoff, sediments and rare earth elements lost from four arable hillslope lengths at a site in the UK with clay soils were monitored from three rainfall events after tracer application. Measured erosion rates were low, reflecting the typical event conditions occurring at the site, and less than 1% of the applied REO tracers were recovered, which is consistent with the results of comparable studies. Tracer recovery at the base of the hillslope was able to indicate the relative importance of different hillslope sediment source areas, which were found to be consistent between events. The principal source of eroded sediments was the upslope area, implying that the wheel tracks were principally conduits for sediment transport, and not highly active sites of erosion. Mitigation treatments for sediment losses from arable hillslopes should therefore focus on methodologies for trapping mobile sediments within wheel track areas through increasing surface roughness or reducing the connectivity of sediment transport processes.
The role of bedrock groundwater in rainfall-runoff response at hillslope and catchment scales
Gabrielli, C. P.; McDonnell, J. J.; Jarvis, W. T.
2012-07-01
SummaryBedrock groundwater dynamics in headwater catchments are poorly understood and poorly characterized. Direct hydrometric measurements have been limited due to the logistical challenges associated with drilling through hard rock in steep, remote and often roadless terrain. We used a new portable bedrock drilling system to explore bedrock groundwater dynamics aimed at quantifying bedrock groundwater contributions to hillslope flow and catchment runoff. We present results from the Maimai M8 research catchment in New Zealand and Watershed 10 (WS10) at the H.J. Andrews Experimental Forest in Oregon, USA. Analysis of bedrock groundwater at Maimai, through a range of flow conditions, revealed that the bedrock water table remained below the soil-bedrock interface, indicating that the bedrock aquifer has minimal direct contributions to event-based hillslope runoff. However, the bedrock water table did respond significantly to storm events indicating that there is a direct connection between hillslope processes and the underlying bedrock aquifer. WS10 groundwater dynamics were dominated by fracture flow. A highly fractured and transmissive zone within the upper one meter of bedrock conducted rapid lateral subsurface stormflow and lateral discharge. The interaction of subsurface stormflow with bedrock storage directly influenced the measured hillslope response, solute transport and computed mean residence time. This research reveals bedrock groundwater to be an extremely dynamic component of the hillslope hydrological system and our comparative analysis illustrates the potential range of hydrological and geological controls on runoff generation in headwater catchments.
Virtual experiments: a new approach for improving process conceptualization in hillslope hydrology
Weiler, Markus; McDonnell, Jeff
2004-01-01
We present an approach for process conceptualization in hillslope hydrology. We develop and implement a series of virtual experiments, whereby the interaction between water flow pathways, source and mixing at the hillslope scale is examined within a virtual experiment framework. We define these virtual experiments as 'numerical experiments with a model driven by collective field intelligence'. The virtual experiments explore the first-order controls in hillslope hydrology, where the experimentalist and modeler work together to cooperatively develop and analyze the results. Our hillslope model for the virtual experiments (HillVi) in this paper is based on conceptualizing the water balance within the saturated and unsaturated zone in relation to soil physical properties in a spatially explicit manner at the hillslope scale. We argue that a virtual experiment model needs to be able to capture all major controls on subsurface flow processes that the experimentalist might deem important, while at the same time being simple with few 'tunable parameters'. This combination makes the approach, and the dialog between experimentalist and modeler, a useful hypothesis testing tool. HillVi simulates mass flux for different initial conditions under the same flow conditions. We analyze our results in terms of an artificial line source and isotopic hydrograph separation of water and subsurface flow. Our results for this first set of virtual experiments showed how drainable porosity and soil depth variability exert a first order control on flow and transport at the hillslope scale. We found that high drainable porosity soils resulted in a restricted water table rise, resulting in more pronounced channeling of lateral subsurface flow along the soil-bedrock interface. This in turn resulted in a more anastomosing network of tracer movement across the slope. The virtual isotope hydrograph separation showed higher proportions of event water with increasing drainable porosity. When
Spatial variability of soil erosion and soil quality on hillslopes in the Chinese loess plateau
Li, Y.; Lindstrom, M.J.; Zhang, J.; Yang, J.
2000-01-01
Soil erosion rates and soil quality indicators were measured along two hillslope transects in the Loess Plateau near Yan'an, China. The objectives were to: (a) quantify spatial patterns and controlling processes of soil redistribution due to water and tillage erosion, and (b) correlate soil quality parameters with soil redistribution along the hillslope transects for different land use management systems. Water erosion data were derived from 137 Cs measurements and tillage erosion from the simulation of a Mass Balance Model along the hillslope transects. Soil quality measurements, i.e. soil organic matter, bulk density and available nutrients were made at the same sampling locations as the 137 Cs measurements. Results were compared at the individual site locations and along the hillslope transect through statistical and applied time series analysis. The results showed that soil loss due to water erosion and soil deposition from tillage are the dominant soil redistribution processes in range of 23-40 m, and soil deposition by water erosion and soil loss by tillage are dominant processes occurring in range of more than 80 m within the cultivated landscape. However, land use change associated with vegetation cover can significantly change both the magnitudes and scale of these spatial patterns within the hillslope landscapes. There is a strong interaction between the spatial patterns of soil erosion processes and soil quality. It was concluded that soil loss by water erosion and deposition by tillage are the main cause for the occurrence of significant scale dependency of spatial variability of soil quality along hillslope transects. (author)
Mahmoudi, M.; Sklar, L. S.; Leclere, S.; Davis, J. D.; Stine, A.
2017-12-01
The size distributions of sediment produced on hillslopes and supplied to river channels influence a wide range of fluvial processes, from bedrock river incision to the creation of aquatic habitats. However, the factors that control hillslope sediment size are poorly understood, limiting our ability to predict sediment size and model the evolution of sediment size distributions across landscapes. Recently separate field and theoretical investigations have begun to address this knowledge gap. Here we compare the predictions of several emerging modeling approaches to landscapes where high quality field data are available. Our goals are to explore the sensitivity and applicability of the theoretical models in each field context, and ultimately to provide a foundation for incorporating hillslope sediment size into models of landscape evolution. The field data include published measurements of hillslope sediment size from the Kohala peninsula on the island of Hawaii and tributaries to the Feather River in the northern Sierra Nevada mountains of California, and an unpublished data set from the Inyo Creek catchment of the southern Sierra Nevada. These data are compared to predictions adapted from recently published modeling approaches that include elements of topography, geology, structure, climate and erosion rate. Predictive models for each site are built in ArcGIS using field condition datasets: DEM topography (slope, aspect, curvature), bedrock geology (lithology, mineralogy), structure (fault location, fracture density), climate data (mean annual precipitation and temperature), and estimates of erosion rates. Preliminary analysis suggests that models may be finely tuned to the calibration sites, particularly when field conditions most closely satisfy model assumptions, leading to unrealistic predictions from extrapolation. We suggest a path forward for developing a computationally tractable method for incorporating spatial variation in production of hillslope
Spatial patterns and controls of soil chemical weathering rates along a transient hillslope
Yoo, K.; Mudd, S.M.; Sanderman, J.; Amundson, Ronald; Blum, A.
2009-01-01
Hillslopes have been intensively studied by both geomorphologists and soil scientists. Whereas geomorphologists have focused on the physical soil production and transport on hillslopes, soil scientists have been concerned with the topographic variation of soil geochemical properties. We combined these differing approaches and quantified soil chemical weathering rates along a grass covered hillslope in Coastal California. The hillslope is comprised of both erosional and depositional sections. In the upper eroding section, soil production is balanced by physical erosion and chemical weathering. The hillslope then transitions to a depositional slope where soil accumulates due to a historical reduction of channel incision at the hillslope's base. Measurements of hillslope morphology and soil thickness were combined with the elemental composition of the soil and saprolite, and interpreted through a process-based model that accounts for both chemical weathering and sediment transport. Chemical weathering of the minerals as they moved downslope via sediment transport imparted spatial variation in the geochemical properties of the soil. Inverse modeling of the field and laboratory data revealed that the long-term soil chemical weathering rates peak at 5 g m- 2 yr- 1 at the downslope end of the eroding section and decrease to 1.5 g m- 2 yr- 1 within the depositional section. In the eroding section, soil chemical weathering rates appear to be primarily controlled by the rate of mineral supply via colluvial input from upslope. In the depositional slope, geochemical equilibrium between soil water and minerals appeared to limit the chemical weathering rate. Soil chemical weathering was responsible for removing 6% of the soil production in the eroding section and 5% of colluvial influx in the depositional slope. These were among the lowest weathering rates reported for actively eroding watersheds, which was attributed to the parent material with low amount of weatherable
"Physically-based" numerical experiment to determine the dominant hillslope processes during floods?
Gaume, Eric; Esclaffer, Thomas; Dangla, Patrick; Payrastre, Olivier
2016-04-01
To study the dynamics of hillslope responses during flood event, a fully coupled "physically-based" model for the combined numerical simulation of surface runoff and underground flows has been developed. A particular attention has been given to the selection of appropriate numerical schemes for the modelling of both processes and of their coupling. Surprisingly, the most difficult question to solve, from a numerical point of view, was not related to the coupling of two processes with contrasted kinetics such as surface and underground flows, but to the high gradient infiltration fronts appearing in soils, source of numerical diffusion, instabilities and sometimes divergence. The model being elaborated, it has been successfully tested against results of high quality experiments conducted on a laboratory sandy slope in the early eighties, which is still considered as a reference hillslope experimental setting (Abdul & Guilham). The model appeared able to accurately simulate the pore pressure distributions observed in this 1.5 meter deep and wide laboratory hillslope, as well as its outflow hydrograph shapes and the measured respective contributions of direct runoff and groundwater to these outflow hydrographs. Based on this great success, the same model has been used to simulate the response of a theoretical 100-meter wide and 10% sloped hillslope, with a 2 meter deep pervious soil and impervious bedrock. Three rain events have been tested: a 100 millimeter rainfall event over 10 days, over 1 day or over one hour. The simulated responses are hydrologically not realistic and especially the fast component of the response, that is generally observed in the real-world and explains flood events, is almost absent of the simulated response. Thinking a little about the whole problem, the simulation results appears totally logical according to the proposed model. The simulated response, in fact a recession hydrograph, corresponds to a piston flow of a relatively uniformly
Borella, Josh; Quigley, Mark; Sohbati, Reza
2016-01-01
of Polynesians (ca. AD 1280) and Europeans (ca. AD 1800) in New Zealand, and suggest loess accumulation was continuing at the study site until 12–13 ka. Large (>5m3) prehistoric rockfall boulders preserve an important record of Holocene hillslope sedimentation by creating local traps (i.e. accommodation space......) for sediment aggradation (i.e. colluvial wedges) and upbuilding soil formation. Sediment accumulation rates increased considerably (>10 factor increase) following human arrival and associated anthropogenic burning of hillslope vegetation. Our study presents new numerical ages to place the evolution of loess...
The role of hillslope topography on shallow landslides activation and basin saturation propensity
Lanni, C.; Pretto, I.; Rigon, R.
2009-12-01
Shallow Landslides are one of the most important causes of loss of human life and socio-economic damage related to the hydro-geological risk issues. In the past years a big number of researches have developed tools to assess for the stability condition of hillslopes at the basin-scale. Montgomery and Dietrich (1994), for instance, with their own SHALSTAB model, give a simple way to evaluate the safety factor of mountain hillslopes, coupling the infinite slope stability model with a very simple steady-state hydrological model based on the work by O'Loughlin (1986) and which has similarities to TOPOG (Beven and Kirkby, 1979). The state of art gives the possibility to evaluate the transient nature of the generated pore-pressure fields within soil-thickness during and after the rainfalls. A valuable tool to fulfill this purpose may be the GEOtop model (Rigon et al., 2006) born to solve the 3-dimensional form of Richards’ equation. The present work, which was held using GEOtop model, investigates the stability conditions and the water table level of nine characteristic hillslope types when steady-state conditions are reached. The artificial simple basins are created combining three different curvature's profile (straight, concave and convex) and three different plan shapes (parallel, convergent and divergent) (fig.1). In the analysis the hillslope soil thickness is imposed constant, while the bedrock is considered impermeable. Different intensity rainfalls are simulated. The results show that in the case of the lowest intensity rainfall, basins with convex shape present higher percentage of saturated area than concave and straight ones. Also, convergent hillslopes generally produce a higher percentage of saturated area than the other plan shapes. Moreover, in the case of higher intensity rainfalls, the concave profile curvature seems to be the first order controller on the saturation process. Regarding the stability conditions, convergent hillslopes generally presents
Variability of sap flow on forest hillslopes: patterns and controls
Hassler, Sibylle; Blume, Theresa
2013-04-01
Sap flow in trees is an essential variable in integrated studies of hydrologic fluxes. It gives indication of transpiration rates for single trees and, with a suitable method of upscaling, for whole stands. This information is relevant for hydrologic and climate models, especially for the prediction of change in water fluxes in the soil-plant-atmosphere continuum under climate change. To this end, we do not only need knowledge concerning the response of sapflow to atmospheric forcing but also an understanding of the main controls on its spatial variability. Our study site consists of several subcatchments of the Attert basin in Luxembourg underlain by schists of the Ardennes massif. Within these subcatchments we measure sap flow in more than 20 trees on a range of forested hillslopes covered by a variety of temperate deciduous tree species such as beech, oak, hornbeam and maple as well as conifers such as firs. Our sap flow sensors are based on the heat pulse velocity method and consist of three needles, one needle acting as the heating device and the other two holding three thermistors each, enabling us to simultaneously measure sap flow velocity at three different depths within the tree. In close proximity to the trees we collect additional data on soil moisture, matric potential and groundwater levels. First results show that the sensor design seems promising for an upscaling of the measured sap flow velocities to sap flow at the tree level. The maximum depth of actively used sapwood as well as the decrease in sap flow velocity with increasing depth in the tree can be determined by way of the three thermistors. Marked differences in sap flow velocity profiles are visible between the different species, resulting in differences in sap flow for trees of similar diameter. We examine the range of tree sap flow values and variation due to species, size class, slope position and exposition and finally relate them to the dynamics of soil moisture conditions with the
Bedrock hillslopes to deltas: New insights into landscape mechanics
Lamb, M. P.
2012-12-01
A powerful record of environmental history on Earth and other planets is preserved in landscapes and sedimentary deposits formed by erosion, transport and deposition of sediment. To understand this record and predict future landscape change, we need mechanistic theories for transport processes and morphodynamics. Significant progress has been made to develop and test transport laws in some settings including soil-mantled landscapes and modest gradient alluvial channels where conventional hydraulic and sediment-transport theories apply. Fundamental opportunities exist, however, to explore the physical limits of existing theories and develop new theories at the frontier of our knowledge base. In this presentation, I will describe recent case studies from sediment-source areas to depositional sinks designed to test the limits of existing transport theories and identify transitions in dominant geomorphic processes by pushing to steeper slopes, greater discharges, and dynamic boundary conditions. First, field measurements, laboratory experiments and theory suggest that sediment transport on steep, rocky hillslopes is different than on soil mantled landscapes, and may be controlled by vegetation dams and sediment release following wildfire. Second, laboratory experiments show that grain stability is enhanced in steep mountain channels compared to moderate gradient channels due to the coincident change in the ratio of flow depth to grain size, until the threshold for mass failure is surpassed. Third, field observations and theory indicate that canyons can be cut by extreme floods at rates that exceed typical river-incision rates by many orders of magnitude due to the transition from abrasion to plucking and toppling of jointed rock, with implications for megafloods on Mars. Finally, numerical modeling, laboratory experiments, and field work show that coastal rivers are coupled to their offshore plumes, and that this coupling may determine the size of deltas. These case
An evaluation of the hydrologic relevance of lateral flow in snow at hillslope and catchment scales
David Eiriksson; Michael Whitson; Charles H. Luce; Hans Peter Marshall; John Bradford; Shawn G. Benner; Thomas Black; Hank Hetrick; James P. McNamara
2013-01-01
Lateral downslope flow in snow during snowmelt and rain-on-snow (ROS) events is a well-known phenomenon, yet its relevance to water redistribution at hillslope and catchment scales is not well understood. We used dye tracers, geophysical methods, and hydrometric measurements to describe the snow properties that promote lateral flow, assess the relative velocities of...
The distribution of hillslope-channel interactions in a rangeland watershed
Leslie M. Reid
1998-01-01
The distribution of erosion and deposition in a basin--and thus of the major controls on basin evolution--is dependent upon the local balance between sediment transport and sediment supply. This balance, in turn, reflects the nature, strength, and distribution of interactions between hillslope and channel processes.
When interflow also percolates: downslope travel distances and hillslope process zones.
Jackson, C. Rhett [Warnell School of Forestry and Natural Resources, University of Georgia, GA 30602 Athens USA; Bitew, Menberu [Warnell School of Forestry and Natural Resources, University of Georgia, GA 30602 Athens USA; Du, Enhao [Climate Science Department, Lawrence Berkeley National Laboratory, CA 94720 Berkeley USA
2014-02-17
In hillslopes with soils characterized by deep regoliths, such as Ultisols,Oxisols, and Alfisols, interflow occurs episodically over impeding layers near and parallel to the soil surface such as low-conductivity B horizons (e.g.Newman et al., 1998; Buttle andMcDonald, 2002; Du et al., In Review), till layers (McGlynn et al., 1999; Bishop et al., 2004), hardpans (McDaniel et al., 2008), C horizons (Detty and McGuire, 2010), and permeable bedrock (Tromp van Meerveld et al., 2007). As perched saturation develops within and above these impeding but permeable horizons, flow moves laterally downslope, but the perched water also continues to percolate through the impeding horizon to the unsaturated soils and saprolite below. Perched water and solutes will eventually traverse the zone of perched saturation above the impeding horizon and then enter and percolate through the impeding horizon. In such flow situations, only lower hillslope segments with sufficient downslope travel distance will deliver water to the riparian zone within the time scale of a storm.farther up the slope, lateral flow within the zone of perched saturation. will act mainly to shift the point of percolation (location where a water packet leaves the downslope flow zone in the upper soil layer and enters the impeding layer) down the hillslope from the point of infiltration. In flatter parts of the hillslope or in areas with little contrast between the conductivities of the upper and impeding soil layers, lateral flow distances will be negligible.
Impact of Vegetative Cover on Runoff and Soil Erosion at Hillslope Scale in Lanjaron, Spain
Duran Zuazo, V.H.; Francia-Martinez, J.R.; Martinez-Raya, A.
2004-01-01
Soil loss and surface runoff patterns over a four-year period (1997¿2000) were studied in erosion plots from three hillslopes under different vegetative covers (Rosmarinus officinalis, Triticum aestivum and natural-spontaneous vegetation) in Lanjaron (Alpujarras) on the south flank of the Sierra
Rainfall Simulator Experiments to Investigate Macropore Impacts on Hillslope Hydrological Response
Smit, Y.; Teuling, Adriaan J.; van der Ploeg, Martine J.
2016-01-01
Understanding hillslope runoff response to intense rainfall is an important topic in hydrology, and is key to correct prediction of extreme stream flow, erosion and landslides. Although it is known that preferential flow processes activated by macropores are an important phenomena in understanding
Variability in soil CO2 production and surface CO2 efflux across riparian-hillslope transitions
Vincent Jerald. Pacific
2007-01-01
The spatial and temporal controls on soil CO2 production and surface CO2 efflux have been identified as an outstanding gap in our understanding of carbon cycling. I investigated both the spatial and temporal variability of soil CO2 concentrations and surface CO2 efflux across eight topographically distinct riparian-hillslope transitions in the ~300 ha subalpine upper-...
H.R. Barnard; C.B. Graham; W.J. van Verseveld; J.R. Brooks; B.J. Bond; J.J. McDonnell
2010-01-01
Mechanistic assessment of how transpiration influences subsurface flow is necessary to advance understanding of catchment hydrology. We conducted a 24-day, steady-state irrigation experiment to quantify the relationships among soil moisture, transpiration and hillslope subsurface flow. Our objectives were to: (1) examine the time lag between maximum transpiration and...
Structural and functional connectivity as a driver of hillslope erosion following disturbance
C. Jason Williams; Frederick B. Pierson; Pete Robichaud; Osama Z. Al-Hamdan; Jan Boll; Eva K. Strand
2016-01-01
Hydrologic response to rainfall on fragmented or burnt hillslopes is strongly influenced by the ensuing connectivity of runoff and erosion processes. Yet cross-scale process connectivity is seldom evaluated in field studies owing to scale limitations in experimental design. This study quantified surface susceptibility and hydrologic response across point to...
A 1-D mechanistic model for the evolution of earthflow-prone hillslopes
Booth, Adam M.; Roering, Josh J.
2011-12-01
In mountainous terrain, deep-seated landslides transport large volumes of material on hillslopes, exerting a dominant control on erosion rates and landscape form. Here, we develop a mathematical landscape evolution model to explore interactions between deep-seated earthflows, soil creep, and gully processes at the drainage basin scale over geomorphically relevant (>103 year) timescales. In the model, sediment flux or incision laws for these three geomorphic processes combine to determine the morphology of actively uplifting and eroding steady state topographic profiles. We apply the model to three sites, one in the Gabilan Mesa, California, with no earthflow activity, and two along the Eel River, California, with different lithologies and varying levels of historic earthflow activity. Representative topographic profiles from these sites are consistent with model predictions in which the magnitude of a dimensionless earthflow number, based on a non-Newtonian flow rheology, reflects the magnitude of recent earthflow activity on the different hillslopes. The model accurately predicts the behavior of earthflow collection and transport zones observed in the field and estimates long-term average sediment fluxes that are due to earthflows, in agreement with historical rates at our field sites. Finally, our model predicts that steady state hillslope relief in earthflow-prone terrain increases nonlinearly with the tectonic uplift rate, suggesting that the mean hillslope angle may record uplift rate in earthflow-prone landscapes even at high uplift rates, where threshold slope processes normally limit further topographic development.
Vertical and lateral soil moisture patterns on a Mediterranean karst hillslope
Canton Yolanda
2016-09-01
Full Text Available The need for a better understanding of factors controlling the variability of soil water content (θ in space and time to adequately predict the movement of water in the soil and in the interphase soil-atmosphere is widely recognised. In this paper, we analyse how soil properties, surface cover and topography influence soil moisture (θ over karstic lithology in a sub-humid Mediterranean mountain environment. For this analysis we have used 17 months of θ measurements with a high temporal resolution from different positions on a hillslope at the main recharge area of the Campo de Dalías aquifer, in Sierra de Gádor (Almería, SE Spain. Soil properties and surface cover vary depending on the position at the hillslope, and this variability has an important effect on θ. The higher clay content towards the lower position of the hillslope explains the increase of θ downslope at the subsurface horizon throughout the entire period studied. In the surface horizon (0-0.1 m, θ patterns coincide with those found at the subsurface horizon (0.1-0.35 m during dry periods when the main control is also exerted by the higher percentage of clay that increases downslope and limits water depletion through evaporation. However, in wet periods, the wettest regime is found in the surface horizon at the upper position of the hillslope where plant cover, soil organic matter content, available water, unsaturated hydraulic conductivity (Kunsat and infiltration rates are higher than in the lower positions. The presence of rock outcrops upslope the θ sampling area, acts as runoff sources, and subsurface flow generation between surface and subsurface horizons also may increase the differences between the upper and the lower positions of the hillslope during wet periods. Both rock and soil cracks and fissures act disconnecting surface water fluxes and reducing run-on to the lower position of the hillslope and thus they affect θ pattern as well as groundwater recharge
Sweeney, K. E.; Roering, J. J.; Rempel, A. W.
2012-12-01
Convex hilltops formed by diffusive sediment transport are a fundamental feature of soil-mantled landscapes worldwide. Additionally, the competition and interaction between hillslopes and valleys control basic topographic metrics, such as relief, drainage density, and breaks in slope-area scaling. Despite recent progress in erosive landscape experiments, no published work has explored the competition of hillslope diffusion and channel advection experimentally. Here, we present preliminary findings on the plausibility of needle ice driven frost creep as a mechanism for laboratory hillslope transport of wet sediment. In nature, needle ice is a diurnal form of ice segregation, whereby liquid water held in sediment pore space is driven upward toward a near-surface freezing front by a temperature-controlled liquid pressure gradient. As needles grow perpendicular to the surface, sediment is incorporated in the growing needle ice by temperature perturbations and associated downward shifts in the freezing front. Sediment then moves downslope due to melting or sublimation of the ice needles. We constructed a slope of saturated sediment in a freezer to constrain the temperature, grain size, and soil moisture limits on laboratory needle ice growth and sediment transport. Surficial sediment transport is measured during experimentation by tracking the movement of colored grains. Additionally, at the end of each run we measure depth-dependent sediment transport by taking slices of the experimental slope and observing the displacement of buried columns of colored grains. In agreement with past work, we find that with temperatures just below freezing, soil moisture above 35%, and silt-sized sediment, the moisture migration induced by freezing releases enough latent heat to maintain the location of the freezing front and encourage needle ice growth. Our experiments demonstrate that the amount of sediment incorporated during needle growth, i.e., the transport efficiency, can be
Modelling of runoff generation and soil moisture dynamics for hillslopes and micro-catchments
Bronstert, Axel; Plate, Erich J.
1997-11-01
The modelling of hillslope hydrology is of great importance not only for the reason that all non-plain, i.e. hilly or mountainous, landscapes can be considered as being composed of a mosaic of hillslopes. A hillslope model may also be used for both research purposes and for application-oriented, detailed, hillslope-scale hydrological studies in conjunction with related scientific disciplines such as geotechnics, geo-chemistry and environmental technology. Despite the current limited application of multi-process and multi-dimensional hydrological models (particularly at the hillslope scale), hardly any comprehensive model has been available for operational use. In this paper we introduce a model which considers most of the relevant hillslope hydrological processes. Some recent applications are described which demonstrate its ability to narrow the stated gap in hillslope hydrological modelling. The modelling system accounts for the hydrological processes of interception, evapotranspiration, infiltration, soil-moisture movement (where the flow processes can be modelled in three dimensions), surface runoff, subsurface stormflow and streamflow discharge. The relevant process interactions are also included. Special regard has been given to consideration of state-of-the-art knowledge concerning rapid soilwater flow processes during storm conditions (e.g. macropore infiltration, lateral subsurface stormflow, return flow) and to its transfer to and inclusion within an operational modelling scheme. The model is "physically based" in the sense that its parameters have a physical meaning and can be obtained or derived from field measurements. This somewhat weaker than usual definition of a physical basis implies that some of the sub-models (still) contain empirical components, that the effects of the high spatial and temporal variability found in nature cannot always be expressed within the various physical laws, i.e. that the laws are scale dependent, and that due to
Cerovski-Darriau, C.; Roering, J. J.; Bilderback, E. L.
2012-12-01
Base level change can cause differential incision in fluvial networks, driving a transient hillslope response as slopes attempt to adjust to a new base level. Following a shift to a warmer, wetter climate after the Last Glacial Maximum (LGM) (~17.5 ka), the Waipaoa River (NZ) rapidly incised ~120 m leaving perched relict hillslopes that are still adjusting to that base level fall. While previous studies of the Waipaoa basin have only focused on sediment contribution from channel incision or a few individual large earthflows, here we analyze an entire catchment that experiences widespread adjustment due to earthflow activity. In the Mangataikapua catchment—a tributary of the Waipaoa River principally comprised of weak mélange—we see wholesale relaxation of hillslopes due to pervasive post-LGM earthflows. Less than 6% of the mélange area retains relict terrain unaltered by earthflows, exemplifying the importance of including hillslope sediment contribution. Incision has propagated ~9 km upstream along the mainstem of the Mangataikapua (~86% of the channel length) and has created 80 m of relief at the junction with the Waipaoa. Continued adjustment along Mangataikapua tributaries and slopes is evident from knickpoints in the channels and changes in gradient, curvature, and degree of earthflow-altered terrain on the hillslopes. By identifying the location of this transition in channels and on the hillslopes, we can estimate the amount of post-LGM hillslope relaxation. We analyzed 10 major sub-catchments (drainage areas >35,000 m2) in the mélange on the southeastern side of the catchment. We used slope-area plots, in conjunction with normalized steepness index values (ksn) generated with the Stream Profiler (www.geomorphtools.org), to determine the degree to which the tributary channels have adjusted to incision along the mainstem. Preliminary results show an "upper zone" of relict channel morphology with an average curvature value of θ=-0.3 (±0.1 s.d.) and a
Cislaghi, Alessio; Rigon, Emanuel; Lenzi, Mario Aristide; Bischetti, Gian Battista
2018-04-01
Large wood (LW) plays a key role in physical, chemical, environmental, and biological processes in most natural and seminatural streams. However, it is also a source of hydraulic hazard in anthropised territories. Recruitment from fluvial processes has been the subject of many studies, whereas less attention has been given to hillslope recruitment, which is linked to episodic and spatially distributed events and requires a reliable and accurate slope stability model and a hillslope-channel transfer model. The purpose of this study is to develop an innovative LW hillslope-recruitment estimation approach that combines forest stand characteristics in a spatially distributed form, a probabilistic multidimensional slope stability model able to include the reinforcement exerted by roots, and a hillslope-channel transfer procedure. The approach was tested on a small mountain headwater catchment in the eastern Italian Alps that is prone to shallow landslide and debris flow phenomena. The slope stability model (that had not been calibrated) provided accurate performances, in terms of unstable areas identification according to the landslide inventory (AUC = 0.832) and of LW volume estimation in comparison with LW volume produced by inventoried landslides (7702 m3 corresponding to a recurrence time of about 30 years in the susceptibility curve). The results showed that most LW potentially mobilised by landslides does not reach the channel network (only about 16%), in agreement with the few data reported by other studies, as well as the data normalized for unit length of channel and unit length of channel per year (0-116 m3/km and 0-4 m3/km y-1). This study represents an important contribution to LW research. A rigorous and site-specific estimation of LW hillslope recruitment should, in fact, be an integral part of more general studies on LW dynamics, for forest planning and management, and positioning in-channel wood retention structures.
Snowmelt runoff from northern alpine tundra hillslopes: major processes and methods of simulation
W. L. Quinton
2004-01-01
Full Text Available In northern alpine tundra, large slope gradients, late-lying snow drifts and shallow soils overlying impermeable substrates all contribute to large hillslope runoff volumes during the spring freshet. Understanding the processes and pathways of hillslope runoff in this environment is, therefore, critical to understanding the water cycle within northern alpine tundra ecosystems. This study: (a presents the results of a field study on runoff from a sub-alpine tundra hillslope with a large snow drift during the spring melt period; (b identifies the major runoff processes that must be represented in simulations of snowmelt runoff from sub-alpine tundra hillslopes; (c describes how these processes can be represented in a numerical simulation model; and d compares field measurements with modelled output to validate or refute the conceptual understanding of runoff generation embodied in the process simulations. The study was conducted at Granger Creek catchment, 15 km south of Whitehorse, Yukon Territory, Canada, on a north-facing slope below a late-lying snow drift. For the freshet period, the major processes to be represented in a runoff model include the rate of meltwater release from the late-lying snowdrift, the elevation and thickness of the saturated layer, the magnitude of the soil permeability and its variation with depth. The daily cycle of net all-wave radiation was observed to drive the diurnal pulses of melt water from the drift; this, in turn, was found to control the daily pulses of flow through the hillslope subsurface and in the stream channel. The computed rate of frost table lowering fell within the observed values; however, there was wide variation among the measured frost table depths. Spatial variability in frost table depth would result in spatial variabilities in saturated layer depth and thickness, which would, in turn, produce variations in subsurface flow rates over the slope, including preferential flowpaths. Keywords
Co-evolution of Vegetation, Sediment Transport and Infiltration on semi-arid hillslopes
Harman, C. J.; Troch, P. A.; Lohse, K. A.; Sivapalan, M.
2011-12-01
Soils in semi-arid landscapes can vary over very small distances, with a great deal of variation associated with 'resource islands' created and maintained by woody vegetation. The distinct physical and hydraulic properties that arise in these islands can lead to spatial patterns of infiltration that have been implicated in the maintenance of the vegetation populating the island. Less well understood are the roles that the small-scale variability in soils plays in determining the transport of sediments, water and sediment-bound carbon and nitrogen across hillslopes. Here we explore these relationships using a coupled field and modeling approach. Detailed field data from hillslopes underlain by both granite and schist parent materials in the Santa Catalina mountains (part of the JSC Critical Zone Observatory) suggest that soils under individual velvet mesquite (latin name) contain higher concentration of soil organic matter and have higher hydraulic conductivity and water holding capacity. Greater infiltration and increased roughness under the canopy appears to lead to the formation of mounds that alter overland flow lines around the area under the canopy, particularly in the finer schist soils. This diversion leads to a complex distribution of shear stresses across the hillslope, creating systematic patterns in the transport of carbon and nitrogen rich soils under the canopies. The relationship between the small scale mechanism and the emergent pattern dynamics in the temporal variability of materials delivered to the stream from the hillslope are also examined, and the implications of these results for the modeling of water, sediment and nutrient fluxes at hillslope scales will be discussed.
Hübner, R.; Heller, K.; Günther, T.; Kleber, A.
2015-01-01
Besides floodplains, hillslopes are basic units that mainly control water movement and flow pathways within catchments of subdued mountain ranges. The structure of their shallow subsurface affects water balance, e.g. infiltration, retention, and runoff. Nevertheless, there is still a gap in the knowledge of the hydrological dynamics on hillslopes, notably due to the lack of generalization and transferability. This study presents a robust multi-method framework of electrical resistivity tomography (ERT) in addition to hydrometric point measurements, transferring hydrometric data into higher spatial scales to obtain additional patterns of distribution and dynamics of soil moisture on a hillslope. A geoelectrical monitoring in a small catchment in the eastern Ore Mountains was carried out at weekly intervals from May to December 2008 to image seasonal moisture dynamics on the hillslope scale. To link water content and electrical resistivity, the parameters of Archie's law were determined using different core samples. To optimize inversion parameters and methods, the derived spatial and temporal water content distribution was compared to tensiometer data. The results from ERT measurements show a strong correlation with the hydrometric data. The response is congruent to the soil tension data. Water content calculated from the ERT profile shows similar variations as that of water content from soil moisture sensors. Consequently, soil moisture dynamics on the hillslope scale may be determined not only by expensive invasive punctual hydrometric measurements, but also by minimally invasive time-lapse ERT, provided that pedo-/petrophysical relationships are known. Since ERT integrates larger spatial scales, a combination with hydrometric point measurements improves the understanding of the ongoing hydrological processes and better suits identification of heterogeneities.
The hierarchy of controls on snowmelt-runoff generation over seasonally-frozen hillslopes
Coles, Anna E.; Appels, Willemijn M.; McConkey, Brian G.; McDonnell, Jeffrey J.
2016-01-01
Understanding and modeling snowmelt-runoff generation in seasonally-frozen regions is a major challenge in hydrology. Partly, this is because the controls on hillslope-scale snowmelt-runoff generation are potentially extensive and their hierarchy is poorly understood. Understanding the relative importance of controls (e.g. topography, vegetation, land use, soil characteristics, and precipitation dynamics) on runoff response is necessary for model development, spatial extrapolation, and runoff...
Inter-annual and spatial variability in hillslope runoff and mercury flux during spring snowmelt.
Haynes, Kristine M; Mitchell, Carl P J
2012-08-01
Spring snowmelt is an important period of mercury (Hg) export from watersheds. Limited research has investigated the potential effects of climate variability on hydrologic and Hg fluxes during spring snowmelt. The purpose of this research was to assess the potential impacts of inter-annual climate variability on Hg mobility in forested uplands, as well as spatial variability in hillslope hydrology and Hg fluxes. We compared hydrological flows, Hg and solute mobility from three adjacent hillslopes in the S7 watershed of the Marcell Experimental Forest, Minnesota during two very different spring snowmelt periods: one following a winter (2009-2010) with severely diminished snow accumulation (snow water equivalent (SWE) = 48 mm) with an early melt, and a second (2010-2011) with significantly greater winter snow accumulation (SWE = 98 mm) with average to late melt timing. Observed inter-annual differences in total Hg (THg) and dissolved organic carbon (DOC) yields were predominantly flow-driven, as the proportion by which solute yields increased was the same as the increase in runoff. Accounting for inter-annual differences in flow, there was no significant difference in THg and DOC export between the two snowmelt periods. The spring 2010 snowmelt highlighted the important contribution of melting soil frost in the timing of a considerable portion of THg exported from the hillslope, accounting for nearly 30% of the THg mobilized. Differences in slope morphology and soil depths to the confining till layer were important in controlling the large observed spatial variability in hydrological flowpaths, transmissivity feedback responses, and Hg flux trends across the adjacent hillslopes.
Brillante, Luca; Bois, Benjamin; Mathieu, Olivier; Leveque, Jean
2014-05-01
Hillslope vineyards show various and complex water dynamics between soil and plants, and in order to gain further insight into this phenomenon, 8 grapevine plots were monitored during three vintages, from 2010 to 2013, on Corton Hill, Burgundy, France. Plots were distributed along a topolithosequence from 330 to 270 metres a.s.l. Grapevine water status was monitored weekly by surveying water potential, and, at the end of the season, by the use of the δ13C analysis of grape juice. Soil profile of each plot was described and analysed (soil texture, gravel content, organic carbon, total nitrogen, pH, CEC). Soil volumetric humidity was measured weekly, using TDR probes. A pedotransfer function was developed to transform Electrical Resistivity Imaging (ERI) into soil volume wetness and therefore to spatialise and observe variation in the Fraction of Transpirable Soil Water (FTSW). During the three years of monitoring, grapevines experienced great variation in water status, which ranged from low to considerable water deficit (as expressed by pre-dawn leaf water potential and δ13C analysis of grape juice). With ERI imaging, it was possible to observe differences in water absorption pattern by roots, in different soils, and at different depth. In addition, significant differences were observed in grapevine water status in relation to variations in the physical characteristics of the terroir along the hillslope (i.e. the geo-pedological context, the elevation etc.). Grapevine water behaviour and plant-soil water relationships on the hillslope of Corton Hill have been extensively characterised in this study by ultimate technologies, allowing to present this terroir as a very interesting example for future generalisation and modelling of the hillslope vineyard water dynamics.
Papanicolaou, Athanasios N.; Abban, Benjamin K. B.; Dermisis, Dimitrios C.; Giannopoulos, Christos P.; Flanagan, Dennis C.; Frankenberger, James R.; Wacha, Kenneth M.
2018-01-01
An improved modeling framework for capturing the effects of space and time-variant resistance to overland flow is developed for intensively managed landscapes. The framework builds on the WEPP model but it removes the limitations of the "equivalent" plane and time-invariant roughness assumption. The enhanced model therefore accounts for spatiotemporal changes in flow resistance along a hillslope due to changes in roughness, in profile curvature, and downslope variability. The model is used to quantify the degree of influence—from individual soil grains to aggregates, "isolated roughness elements," and vegetation—on overland flow characteristics under different storm magnitudes, downslope gradients, and profile curvatures. It was found that the net effects of land use change from vegetation to a bare surface resulted in hydrograph peaks that were up to 133% larger. Changes in hillslope profile curvature instead resulted in peak runoff rate changes that were only up to 16%. The stream power concept is utilized to develop a taxonomy that relates the influence of grains, isolated roughness elements, and vegetation, on overland flow under different storm magnitudes and hillslope gradients. Critical storm magnitudes and hillslope gradients were found beyond which the effects of these landscape attributes on the peak stream power were negligible. The results also highlight weaknesses of the space/time-invariant flow resistance assumption and demonstrate that assumptions on landscape terrain characteristics exert a strong control both on the shape and magnitude of hydrographs, with deviations reaching 65% in the peak runoff when space/time-variant resistance effects are ignored in some cases.
Hillslope Erosion and Water Quality from the Rim Fire, Sierra Nevada, CA
Kuhn, T. J.; Austin, L. J.; Forrester, H.; DeLong, S. B.; Lever, R.; Roche, J. W.
2014-12-01
The Rim Fire in 2013 burned approximately 1036 km2 in the Sierra Nevada (including 312 km2 within Yosemite National Park), generating considerable public concern regarding potential impacts to the Tuolumne River watershed, in terms of water quality and water supply infrastructure serving the City of San Francisco. Land management responses included a multi-million dollar watershed treatment project on USFS lands near Cherry Creek, with similar actions suggested for areas in the Hetch Hetchy and Lake Eleanor watersheds. In response to the concern that the post-burn landscape will negatively impact water quality, we are investigating hydrologic effects and hillslope erosion in two small burned basins (2.2 and 5.2 km2) within the Tuolumne River basin in Yosemite National Park. Within a month after fire containment, sites were equipped with instrumentation to record stream stage, turbidity, and total suspended sediment. We also installed 21 sediment fences that trap all sediment silt sized and larger on moderate (20%) to steep (50%) hillslopes from 100 m2 plots within moderate and high severity burn areas. Accumulated sediment is collected, weighed, and sub-sampled after each storm event, and, analyzed for dry weight, particle size, gravimetric water content, bulk density, pH, color, carbon and nitrogen content from % fine organics, and % coarse organics. As of July 31, 2014, four discrete storm events had been sampled. Data are used to calculate annual sediment yield, and to investigate organic carbon storage, deposition, and transport. We are also collecting repeat terrestrial laser scans to assess topographic change and identify the hillslope processes that contribute to erosion and deposition at plot- and hillslope-scale. These findings provide analogs for possible changes in adjacent burned areas and to inform management decisions in response to future fires and potential impacts to water quality in areas valued by the park, the City of San Francisco and other
Willgoose, G. R.; Cohen, S.; Svoray, T.; Sela, S.; Hancock, G. R.
2010-12-01
Numerical models are an important tool for studying landscape processes as they allow us to isolate specific processes and drivers and test various physics and spatio-temporal scenarios. Here we use a distributed physically-based soil evolution model (mARM4D) to describe the drivers and processes controlling soil-landscape evolution on a field-site at the fringe between the Mediterranean and desert regions of Israel. This study is an initial effort in a larger project aimed at improving our understanding of the mechanisms and drivers that led to the extensive removal of soils from the loess covered hillslopes of this region. This specific region is interesting as it is located between the Mediterranean climate region in which widespread erosion from hillslopes was attributed to human activity during the Holocene and the arid region in which extensive removal of loess from hillslopes was shown to have been driven by climatic changes during the late-Pleistocene. First we study the sediment transport mechanism of the soil-landscape evolution processes in our study-site. We simulate soil-landscape evolution with only one sediment transport process (fluvial or diffusive) at a time. We find that diffusive sediment transport is likely the dominant process in this site as it resulted in soil distributions that better corresponds to current observations. We then simulate several realistic climatic/anthropogenic scenarios (based on the literature) in order to quantify the sensitivity of the soil-landscape evolution process to temporal fluctuations. We find that this site is relatively insensitive to short term (several thousands of years) sharp, changes. This suggests that climate, rather then human activity, was the main driver for the extensive removal of loess from the hillslopes.
Effects of large deep-seated landslides on hillslope morphology, western Southern Alps, New Zealand
Korup, Oliver
2006-03-01
Morphometric analysis and air photo interpretation highlight geomorphic imprints of large landslides (i.e., affecting ≥1 km2) on hillslopes in the western Southern Alps (WSA), New Zealand. Large landslides attain kilometer-scale runout, affect >50% of total basin relief, and in 70% are slope clearing, and thus relief limiting. Landslide terrain shows lower mean local relief, relief variability, slope angles, steepness, and concavity than surrounding terrain. Measuring mean slope angle smoothes out local landslide morphology, masking any relationship between large landslides and possible threshold hillslopes. Large failures also occurred on low-gradient slopes, indicating persistent low-frequency/high-magnitude hillslope adjustment independent of fluvial bedrock incision. At the basin and hillslope scale, slope-area plots partly constrain the effects of landslides on geomorphic process regimes. Landslide imprints gradually blend with relief characteristics at orogen scale (102 km), while being sensitive to length scales of slope failure, topography, sampling, and digital elevation model resolution. This limits means of automated detection, and underlines the importance of local morphologic contrasts for detecting large landslides in the WSA. Landslide controls on low-order drainage include divide lowering and shifting, formation of headwater basins and hanging valleys, and stream piracy. Volumes typically mobilized, yet still stored in numerous deposits despite high denudation rates, are >107 m3, and theoretically equal to 102 years of basin-wide debris production from historic shallow landslides; lack of absolute ages precludes further estimates. Deposit size and mature forest cover indicate residence times of 101-104 years. On these timescales, large landslides require further attention in landscape evolution models of tectonically active orogens.
Evaluation of microplastics in Jurujuba Cove, Niterói, RJ, Brazil, an area of mussels farming.
Castro, Rebeca Oliveira; Silva, Melanie L; Marques, Mônica Regina C; de Araújo, Fábio V
2016-09-15
Once non-biodegradable, microplastics remain on the environment absorbing toxic hydrophobic compounds making them a risk to biodiversity when ingested or filtered by organisms and entering in the food chain. To evaluate the potential of the contamination by microplastics in mussels cultivated in Jurujuba Cove, Niterói, RJ, waters of three stations were collected during a rain and dry seasons using a plankton net and later filtered. Microplastics were quantified and characterized morphologically and chemically. The results showed a high concentration of microplastics in both seasons with diversity of colors, types and sizes. Synthetic polymers were present in all samples. The presence of microplastics was probably due to a high and constant load of effluent that this area receives and to the mussel farming activity that use many plastic materials. Areas with high concentrations of microplastics could not be used for mussel cultivation due to the risk of contamination to consumers. Copyright © 2016 Elsevier Ltd. All rights reserved.
May, Christine; Roering, Joshua J.; Snow, Kyle; Griswold, Kitty; Gresswell, Robert E.
2017-01-01
Waterfalls create barriers to fish migration, yet hundreds of isolated salmonid populations exist above barriers and have persisted for thousands of years in steep mountainous terrain. Ecological theory indicates that small isolated populations in disturbance-prone landscapes are at greatest risk of extirpation because immigration and recolonization are not possible. On the contrary, many above-barrier populations are currently thriving while their downstream counterparts are dwindling. This quandary led us to explore geomorphic knickpoints as a mechanism for disconnecting hillslope and channel processes by limiting channel incision and decreasing the pace of base-level lowering. Using LiDAR from the Oregon Coast Range, we found gentler channel gradients, wider valleys, lower gradient hillslopes, and less shallow landslide potential in an above-barrier catchment compared to a neighboring catchment devoid of persistent knickpoints. Based on this unique geomorphic template, above-barrier channel networks are less prone to debris flows and other episodic sediment fluxes. These above-barrier catchments also have greater resiliency to flooding, owing to wider valleys with greater floodplain connectivity. Habitat preference models further indicate that salmonid habitat is present in greater quantity and quality in these above-barrier networks. Therefore the paradox of the persistence of small isolated fish populations may be facilitated by a geomorphic mechanism that both limits their connectivity to larger fish populations yet dampens the effect of disturbance by decreasing connections between hillslope and channel processes above geomorphic knickpoints.
Evaluation of the WEPP hillslope model on stable and eroding semiarid woodlands
Wilcox, B.P.; Simanton, J.R.
1995-01-01
In this paper, we evaluate runoff and erosion prediction by the WEPP hillslope model for two pinyon-juniper sites in New Mexico: one has a low erosion rate (stable site) and the other (unstable site) is eroding at very rapid rates (as a result of landuse and climatic perturbations over the last century). Runoff and erosion measurements were made at plot and hillslope scales at both sites. WEPP was evaluated using both rainfall simulation and natural rainfall data. Rainfall simulation was performed on both vegetated and bare plots. Parameter values used were developed from rainfall simulation experiments and site characteristics. In general, runoff and erosion were underpredicted at both sites but to a much larger degree at the unstable site. On the unstable site predictions were much improved when we used hydraulic conductivity (Ke) derived from the bare plot rainfall simulation. Also of importance, at the unstable site we observed a large increase in erosion as scale increased from the plot to the hillslope as a result of a well developed channel network. These results are preliminary, in that only a few storms were evaluated, however, they do suggest some important strategies for predicting the impact of reduced vegetation cover to erosion in semiarid landscapes
Wienhöfer, J.; Zehe, E.
2012-04-01
Rapid lateral flow processes via preferential flow paths are widely accepted to play a key role for rainfall-runoff response in temperate humid headwater catchments. A quantitative description of these processes, however, is still a major challenge in hydrological research, not least because detailed information about the architecture of subsurface flow paths are often impossible to obtain at a natural site without disturbing the system. Our study combines physically based modelling and field observations with the objective to better understand how flow network configurations influence the hydrological response of hillslopes. The system under investigation is a forested hillslope with a small perennial spring at the study area Heumöser, a headwater catchment of the Dornbirnerach in Vorarlberg, Austria. In-situ points measurements of field-saturated hydraulic conductivity and dye staining experiments at the plot scale revealed that shrinkage cracks and biogenic macropores function as preferential flow paths in the fine-textured soils of the study area, and these preferential flow structures were active in fast subsurface transport of artificial tracers at the hillslope scale. For modelling of water and solute transport, we followed the approach of implementing preferential flow paths as spatially explicit structures of high hydraulic conductivity and low retention within the 2D process-based model CATFLOW. Many potential configurations of the flow path network were generated as realisations of a stochastic process informed by macropore characteristics derived from the plot scale observations. Together with different realisations of soil hydraulic parameters, this approach results in a Monte Carlo study. The model setups were used for short-term simulation of a sprinkling and tracer experiment, and the results were evaluated against measured discharges and tracer breakthrough curves. Although both criteria were taken for model evaluation, still several model setups
Skov, Daniel S.; Egholm, David L.
2016-04-01
Surface erosion and sediment production seem to have accelerated globally as climate cooled in the Late Cenozoic, [Molnar, P. 2004, Herman et al 2013]. Glaciers emerged in many high mountain ranges during the Quaternary, and glaciation therefore represents a likely explanation for faster erosion in such places. Still, observations and measurements point to increases in erosion rates also in landscapes where erosion is driven mainly by fluvial processes [Lease and Ehlers (2013), Reusser (2004)]. Flume experiments and fieldwork have shown that rates of incision are to a large degree controlled by the sediment load of streams [e.g. Sklar and Dietrich (2001), Beer and Turowski (2015)]. This realization led to the formulation of sediment-flux dependent incision models [Sklar and Dietrich (2004)]. The sediment-flux dependence links incision in the channels to hillslope processes that supply sediment to the channels. The rates of weathering and soil transport on the hillslopes are processes that are likely to respond to changing temperatures, e.g. because of vegetation changes or the occurrence of frost. In this study, we perform computational landscape evolution experiments, where the coupling between fluvial incision and hillslope processes is accounted for by coupling a sediment-flux-dependent model for fluvial incision to a climate-dependent model for weathering and hillslope sediment transport. The computational experiments first of all demonstrate a strong positive feedback between channel and hillslope processes. In general, faster weathering leads to higher rates of channel incision, which further increases the weathering rates, mainly because of hillslope steepening. Slower weathering leads to the opposite result. The experiments also demonstrate, however, that the feedbacks vary significantly between different parts of a drainage network. For example, increasing hillslope sediment production may accelerate incision in the upper parts of the catchment, while at
Owen, J. J.; Dietrich, W. E.; Nishiizumi, K.; Bellugi, D.; Amundson, R.
2008-12-01
Modeling the development of hillslopes using mass balance equations has generated many testable hypotheses related to morphology, process rates, and soil properties, however it is only relatively recently that techniques for constraining these models (such as cosmogenic radionuclides) have become commonplace. As such, many hypotheses related to the effects of boundary conditions or climate on process rates and soil properties have been left untested. We selected pairs of hillslopes along a precipitation gradient in northern Chile (24°-30° S) which were either bounded by actively eroding (bedrock-bedded) channels or by stable or aggradational landforms (pediments, colluvial aprons, valley bottoms). For each hillslope we measured soil properties, atmospheric deposition rates, and bedrock denudation rates. We observe significant changes in soil properties with climate: there is a shift from thick, weathered soils in the semiarid south, to the near absence of soil in the arid middle, to salt-rich soils in the hyperarid north. Coincident with these are dramatic changes in the types and rates of processes acting on the soils. We found relatively quick, biotically-driven soil formation and transport in the south, and very slow, salt-driven processes in the north. Additionally, we observe systematic differences between hillslopes of different boundary condition within the same climate zone, such as thicker soils, gentler slopes, and slower erosion rates on hillslopes with a non-eroding boundary versus an eroding boundary. These support general predictions based on hillslope soil mass balance equations and geomorphic transport laws. Using parameters derived from our field data, we attempt to use a mass balance model of hillslope development to explore the effect of changing boundary conditions and/or shifting climate.
K. Dontsova
2009-12-01
Full Text Available A reactive transport geochemical modeling study was conducted to help predict the mineral transformations occurring over a ten year time-scale that are expected to impact soil hydraulic properties in the Biosphere 2 (B2 synthetic hillslope experiment. The modeling sought to predict the rate and extent of weathering of a granular basalt (selected for hillslope construction as a function of climatic drivers, and to assess the feedback effects of such weathering processes on the hydraulic properties of the hillslope. Flow vectors were imported from HYDRUS into a reactive transport code, CrunchFlow2007, which was then used to model mineral weathering coupled to reactive solute transport. Associated particle size evolution was translated into changes in saturated hydraulic conductivity using Rosetta software. We found that flow characteristics, including velocity and saturation, strongly influenced the predicted extent of incongruent mineral weathering and neo-phase precipitation on the hillslope. Results were also highly sensitive to specific surface areas of the soil media, consistent with surface reaction controls on dissolution. Effects of fluid flow on weathering resulted in significant differences in the prediction of soil particle size distributions, which should feedback to alter hillslope hydraulic conductivities.
Tucker, G. E.
2012-04-01
; that transient landscapes are better than steady state cases for discriminating between models; and that an important part of the job for some rivers is unearthing their valleys after a major event such as an earthquake fills them up. These examples suggest that the 'the simplest possible model' isn't always the one that our intuition expects. A second example concerns hillslope evolution. Laboratory experiments, field measurements, and the- ory make it clear that, as with rivers, the evolution of hillslopes can involve a strongly nonlinear relationship between relief and erosion rate. Models of particle transport suggest that this nonlinearity can arise from increasingly long-distance particle motions as the gradient increases. One current challenge, therefore, is understanding the dynamics of steep, rocky hillslopes. Among the best natural laboratories for studying such hillslopes are normal-fault facets. These features are a bit like time machines: the higher you go, the longer the surface has been exposed to erosion. A simple mathematical model of facet evolution predicts that the slope of the facet is set by the ratio of erosion rate to fault slip rate. Applying this concept to a case study in Italy where the slip rate is known leads to the startling conclusion that the average hillslope erosion rates over the past ~100 ky is about 20 times faster than the Holocene rate. Thus, facet analysis seems to provide a method for documenting hillslope erosion rates and their variation with climate. As the quest continues, there are surely more fascinating surprises in store.
Shilov, Georgi E
1977-01-01
Covers determinants, linear spaces, systems of linear equations, linear functions of a vector argument, coordinate transformations, the canonical form of the matrix of a linear operator, bilinear and quadratic forms, Euclidean spaces, unitary spaces, quadratic forms in Euclidean and unitary spaces, finite-dimensional space. Problems with hints and answers.
Hillslope chemical weathering across Paraná, Brazil: A data mining-GIS hybrid approach
Iwashita, Fabio; Friedel, Michael J.; Filho, Carlos Roberto de Souza; Fraser, Stephen J.
2011-09-01
Self-organizing map (SOM) and geographic information system (GIS) models were used to investigate the nonlinear relationships associated with geochemical weathering processes at local (~100 km 2) and regional (~50,000 km 2) scales. The data set consisted of 1) 22 B-horizon soil variables: P, C, pH, Al, total acidity, Ca, Mg, K, total cation exchange capacity, sum of exchangeable bases, base saturation, Cu, Zn, Fe, B, S, Mn, gammaspectrometry (total count, potassium, thorium, and uranium) and magnetic susceptibility measures; and 2) six topographic variables: elevation, slope, aspect, hydrological accumulated flux, horizontal curvature and vertical curvature. It is characterized at 304 locations from a quasi-regular grid spaced about 24 km across the state of Paraná. This data base was split into two subsets: one for analysis and modeling (274 samples) and the other for validation (30 samples) purposes. The self-organizing map and clustering methods were used to identify and classify the relations among solid-phase chemical element concentrations and GIS derived topographic models. The correlation between elevation and k-means clusters related the relative position inside hydrologic macro basins, which was interpreted as an expression of the weathering process reaching a steady-state condition at the regional scale. Locally, the chemical element concentrations were related to the vertical curvature representing concave-convex hillslope features, where concave hillslopes with convergent flux tends to be a reducing environment and convex hillslopes with divergent flux, oxidizing environments. Stochastic cross validation demonstrated that the SOM produced unbiased classifications and quantified the relative amount of uncertainty in predictions. This work strengthens the hypothesis that, at B-horizon steady-state conditions, the terrain morphometry were linked with the soil geochemical weathering in a two-way dependent process: the topographic relief was a factor on
Hillslope chemical weathering across Paraná, Brazil: a data mining-GIS hybrid approach
Iwashita, Fabio; Friedel, Michael J.; Filho, Carlos Roberto de Souza; Fraser, Stephen J.
2011-01-01
Self-organizing map (SOM) and geographic information system (GIS) models were used to investigate the nonlinear relationships associated with geochemical weathering processes at local (~100 km2) and regional (~50,000 km2) scales. The data set consisted of 1) 22 B-horizon soil variables: P, C, pH, Al, total acidity, Ca, Mg, K, total cation exchange capacity, sum of exchangeable bases, base saturation, Cu, Zn, Fe, B, S, Mn, gammaspectrometry (total count, potassium, thorium, and uranium) and magnetic susceptibility measures; and 2) six topographic variables: elevation, slope, aspect, hydrological accumulated flux, horizontal curvature and vertical curvature. It is characterized at 304 locations from a quasi-regular grid spaced about 24 km across the state of Paraná. This data base was split into two subsets: one for analysis and modeling (274 samples) and the other for validation (30 samples) purposes. The self-organizing map and clustering methods were used to identify and classify the relations among solid-phase chemical element concentrations and GIS derived topographic models. The correlation between elevation and k-means clusters related the relative position inside hydrologic macro basins, which was interpreted as an expression of the weathering process reaching a steady-state condition at the regional scale. Locally, the chemical element concentrations were related to the vertical curvature representing concave–convex hillslope features, where concave hillslopes with convergent flux tends to be a reducing environment and convex hillslopes with divergent flux, oxidizing environments. Stochastic cross validation demonstrated that the SOM produced unbiased classifications and quantified the relative amount of uncertainty in predictions. This work strengthens the hypothesis that, at B-horizon steady-state conditions, the terrain morphometry were linked with the soil geochemical weathering in a two-way dependent process: the topographic relief was a factor on
Spatial variability of hillslope water balance, wolf creek basin, subarctic yukon
Carey, Sean K.; Woo, Ming-Ko
2001-11-01
A hydrological study was conducted between 1997 and 1999 in the subalpine open woodland of the Wolf Creek Basin, Yukon, to assess the interslope water balance variability. The water balance during the snowmelt and summer periods on four hillslopes revealed strong contrasts in process magnitudes and highlighted important factors including frost, vegetation, soils and microclimate that controlled vertical and lateral fluxes of water. Snow accounted for approximately half the annual water input, while differences in accumulation among hillslopes were related to interception properties of vegetation. Available energy at the snow surface controlled the melt sequence and the snow on some slopes disappeared up to two months earlier than others. Snowmelt runoff was confined to slopes with ice-rich substrates that inhibited deep percolation, with the runoff magnitude governed by the snow storage and the antecedent moisture of the desiccated organic soils prior to melt. During summer, evapotranspiration exceeded rainfall, largely sustained by water from the soil moisture reservoir recharged during the melt period. Differences in net radiation on slopes controlled the potential evapotranspiration, with the actual rates limited by the phenology of the deciduous forests and shrubs. Evapotranspiration was further suppressed on slopes where the organic soils became dry in late summer. Summer runoff was confined to slopes with porous organic layers overlying mineral soils to form a two-layer flow system: (1) quickflow in the surface organic layer and (2) slowflow in the mineral soil. Differences in the rates of flow were related to the position of the water table which may rise into the organic layer to activate quickflow. The presence of ice-rich frost and permafrost impeded vertical drainage and indirectly regulated the position of the water table. The location of the hillslope within a basin influenced recharge and discharge dynamics. Slope segments with large inflows sustained
Vectors of subsurface stormflow in a layered hillslope during runoff initiation
M. Retter
2006-01-01
Full Text Available The focus is the experimental assessment of in-situ flow vectors in a hillslope soil. We selected a 100 m2 trenched hillslope study site. During prescribed sprinkling an obliquely installed TDR wave-guide provides for the velocity of the wetting front in its direction. A triplet of wave-guides mounted along the sides of an hypothetical tetrahedron, with its peak pointing down, produces a three-dimensional vector of the wetting front. The method is based on the passing of wetting fronts. We analysed 34 vectors along the hillslope at distributed locations and at soil depths from 11 cm (representing top soil to 40 cm (close to bedrock interface. The mean values resulted as follows vx=16.1 mm min-1, vy=-0.2 mm min-1, and vz=11.9 mm min-1. The velocity vectors of the wetting fronts were generally gravity dominated and downslope orientated. Downslope direction (x-axis dominated close to bedrock, whereas no preference between vertical and downslope direction was found in vectors close to the surface. The velocities along the contours (y-axis varied widely. The Kruskal-Wallis tests indicated that the different upslope sprinkling areas had no influence on the orientation of the vectors. Vectors of volume flux density were also calculated for each triplet. The lateral velocities of the vector approach are compared with subsurface stromflow collected at the downhill end of the slope. Velocities were 25-140 times slower than lateral saturated tracer movements on top of the bedrock. Beside other points, we conclude that this method is restricted to non-complex substrate (skeleton or portion of big stones.
C. Jackisch
2017-07-01
Full Text Available The study deals with the identification and characterization of rapid subsurface flow structures through pedo- and geo-physical measurements and irrigation experiments at the point, plot and hillslope scale. Our investigation of flow-relevant structures and hydrological responses refers to the general interplay of form and function, respectively. To obtain a holistic picture of the subsurface, a large set of different laboratory, exploratory and experimental methods was used at the different scales. For exploration these methods included drilled soil core profiles, in situ measurements of infiltration capacity and saturated hydraulic conductivity, and laboratory analyses of soil water retention and saturated hydraulic conductivity. The irrigation experiments at the plot scale were monitored through a combination of dye tracer, salt tracer, soil moisture dynamics, and 3-D time-lapse ground penetrating radar (GPR methods. At the hillslope scale the subsurface was explored by a 3-D GPR survey. A natural storm event and an irrigation experiment were monitored by a dense network of soil moisture observations and a cascade of 2-D time-lapse GPR trenches. We show that the shift between activated and non-activated state of the flow paths is needed to distinguish structures from overall heterogeneity. Pedo-physical analyses of point-scale samples are the basis for sub-scale structure inference. At the plot and hillslope scale 3-D and 2-D time-lapse GPR applications are successfully employed as non-invasive means to image subsurface response patterns and to identify flow-relevant paths. Tracer recovery and soil water responses from irrigation experiments deliver a consistent estimate of response velocities. The combined observation of form and function under active conditions provides the means to localize and characterize the structures (this study and the hydrological processes (companion study Angermann et al., 2017, this issue.
Jackisch, Conrad; Angermann, Lisa; Allroggen, Niklas; Sprenger, Matthias; Blume, Theresa; Tronicke, Jens; Zehe, Erwin
2017-07-01
The study deals with the identification and characterization of rapid subsurface flow structures through pedo- and geo-physical measurements and irrigation experiments at the point, plot and hillslope scale. Our investigation of flow-relevant structures and hydrological responses refers to the general interplay of form and function, respectively. To obtain a holistic picture of the subsurface, a large set of different laboratory, exploratory and experimental methods was used at the different scales. For exploration these methods included drilled soil core profiles, in situ measurements of infiltration capacity and saturated hydraulic conductivity, and laboratory analyses of soil water retention and saturated hydraulic conductivity. The irrigation experiments at the plot scale were monitored through a combination of dye tracer, salt tracer, soil moisture dynamics, and 3-D time-lapse ground penetrating radar (GPR) methods. At the hillslope scale the subsurface was explored by a 3-D GPR survey. A natural storm event and an irrigation experiment were monitored by a dense network of soil moisture observations and a cascade of 2-D time-lapse GPR trenches. We show that the shift between activated and non-activated state of the flow paths is needed to distinguish structures from overall heterogeneity. Pedo-physical analyses of point-scale samples are the basis for sub-scale structure inference. At the plot and hillslope scale 3-D and 2-D time-lapse GPR applications are successfully employed as non-invasive means to image subsurface response patterns and to identify flow-relevant paths. Tracer recovery and soil water responses from irrigation experiments deliver a consistent estimate of response velocities. The combined observation of form and function under active conditions provides the means to localize and characterize the structures (this study) and the hydrological processes (companion study Angermann et al., 2017, this issue).
Renner, Maik; Hassler, Sibylle K.; Blume, Theresa; Weiler, Markus; Hildebrandt, Anke; Guderle, Marcus; Schymanski, Stanislaus J.; Kleidon, Axel
2016-05-01
We combine ecohydrological observations of sap flow and soil moisture with thermodynamically constrained estimates of atmospheric evaporative demand to infer the dominant controls of forest transpiration in complex terrain. We hypothesize that daily variations in transpiration are dominated by variations in atmospheric demand, while site-specific controls, including limiting soil moisture, act on longer timescales. We test these hypotheses with data of a measurement setup consisting of five sites along a valley cross section in Luxembourg. Both hillslopes are covered by forest dominated by European beech (Fagus sylvatica L.). Two independent measurements are used to estimate stand transpiration: (i) sap flow and (ii) diurnal variations in soil moisture, which were used to estimate the daily root water uptake. Atmospheric evaporative demand is estimated through thermodynamically constrained evaporation, which only requires absorbed solar radiation and temperature as input data without any empirical parameters. Both transpiration estimates are strongly correlated to atmospheric demand at the daily timescale. We find that neither vapor pressure deficit nor wind speed add to the explained variance, supporting the idea that they are dependent variables on land-atmosphere exchange and the surface energy budget. Estimated stand transpiration was in a similar range at the north-facing and the south-facing hillslopes despite the different aspect and the largely different stand composition. We identified an inverse relationship between sap flux density and the site-average sapwood area per tree as estimated by the site forest inventories. This suggests that tree hydraulic adaptation can compensate for heterogeneous conditions. However, during dry summer periods differences in topographic factors and stand structure can cause spatially variable transpiration rates. We conclude that absorption of solar radiation at the surface forms a dominant control for turbulent heat and
Kinner, David A.; Moody, John A.
2008-01-01
Multiple rainfall intensities were used in rainfall-simulation experiments designed to investigate the infiltration and runoff from 1-square-meter plots on burned hillslopes covered by an ash layer of varying thickness. The 1-square-meter plots were on north- and south-facing hillslopes in an area burned by the Overland fire northwest of Boulder near Jamestown on the Front Range of Colorado. A single-nozzle, wide-angle, multi-intensity rain simulator was developed to investigate the infiltration and runoff on steep (30- to 40-percent gradient) burned hillslopes covered with ash. The simulated rainfall was evaluated for spatial variability, drop size, and kinetic energy. Fourteen rainfall simulations, at three intensities (about 20 millimeters per hour [mm/h], 35 mm/h, and 50 mm/h), were conducted on four plots. Measurements during and after the simulations included runoff, rainfall, suspended-sediment concentrations, surface ash layer thickness, soil moisture, soil grain size, soil lost on ignition, and plot topography. Runoff discharge reached a steady state within 7 to 26 minutes. Steady infiltration rates with the 50-mm/h application rainfall intensity approached 20?35 mm/h. If these rates are projected to rainfall application intensities used in many studies of burned area runoff production (about 80 mm/h), the steady discharge rates are on the lower end of measurements from other studies. Experiments using multiple rainfall intensities (three) suggest that runoff begins at rainfall intensities around 20 mm/h at the 1-square-meter scale, an observation consistent with a 10-mm/h rainfall intensity threshold needed for runoff initiation that has been reported in the literature.
Strong feedbacks between hillslope sediment production and channel incision by saltation-abrasion
Lundbek Egholm, David; Faurschou Knudsen, Mads; Sandiford, Mike
2013-04-01
While it is well understood that rivers erode mountain ranges by incising the bedrock and by transporting sediments away from the ranges, the basic physical mechanisms that drive long-term bedrock erosion and control the lifespan of mountain ranges remain uncertain. A particularly challenging paradox is reconciling the dichotomy associated with the high incision rates observed in active mountain belts, and the long-term (108 years) preservation of significant topographic reliefs in inactive orogenic belts (e.g. von Blankenburg, 2005). We have performed three-dimensional computational experiments with a landscape evolution model that couples bedrock landslides and sediment flux-dependent river erosion by saltation-abrasion (Sklar & Dietrich, 2004). The coupled model experiments show strong feedbacks between the channel erosion and the hillslope delivery of sediments. The feedbacks point to hillslope sediment production rate as the main control on channel erosion rates where saltation-abrasion dominates over other fluvial erosion processes. Our models results thus highlight the importance of hillslope sediment production controlled by climate and tectonic activity for scaling erosion rates in fluvial systems. Because of variations in landslide frequency, the feedbacks make tectonic activity a primary driver of fluvial erosion and help clarifying the long-standing paradox associated with the persistence of significant relief in old orogenic belts, up to several hundred-million-years after tectonic activity has effectively ceased. References F. von Blankenburg. The control mechanisms of erosion and weathering at basin scale from cosmogenic nuclides in river sediment. Earth Planet. Sci. Lett. 237, 462-479 (2005). L. S. Sklar, W. E. Dietrich. A mechanistic model for river incision into bedrock by saltating bed load. Water Resour. Res. 40, W06301 (2004).
Wenske, Dirk; Jen, Chia-Hung; Böse, Margot; Lin, Jiun-Chuan
2010-05-01
Being affected frequently by violent weather condition such as typhoons and regular seismic activity, the high mountains of Taiwan belong to the earth's most dynamic landscapes. In the fast-eroding mountain belt of Taiwan, hillslopes and valley systems have been reported to show a high level of coupling (Hovius et al. 2000). In the catchment of the Tachia river numerous bedrock landslides occur frequently as a result of seismic events and typhoons (Lin et al. 2006). This study attempts to take a closer look at the temporal and spatial pattern of hillslope evolution at two study sites in the upper catchement of the Tachia river. Therefore we have carried out a repeated field surveying of active slopes by means of traditional survey instruments and terrestrial laser scanning from early 2008 until late 2009 on a half year basis. Additionally, a set of aerial photos and satellite images from 1969, 1980,2001, 2004, 2007, 2008 and 2009 is used to assess the long-term and short-term changes of the river channel. Near the town of Huan Shan, the valley bottom shows elevations around 1520 m above sea level and the river is draining and upstream area of 155 km². Downstream of Huan Shan lies the confluence of the Tachia River and two of its tributaries, namely the Nanhu River and the Hehuan River. Therefore, the catchment area upstream of second study area in Sung Mao is considerably larger being of 420 km², in that place, the current level of the channel varies around 1425 m above sea level. In the two study areas strong lateral erosion has been observed. In the case of the Sung Mao study area, the latter is linked to a severe aggradation of sediments in the channel since the building of the Dechi Dam downstream. The active hillslopes have been surveyed and their reaction to the typhoons in 2008 and 2009 is studied. Rates of sediment yield from the slopes have been calculated for three periods between April 2008, November 2008, April 2009 and November 2009. Furthermore, the
Sklar, L. S.; Mahmoudi, M.
2016-12-01
Landscape evolution models rarely represent sediment size explicitly, despite the importance of sediment size in regulating rates of bedload sediment transport, river incision into bedrock, and many other processes in channels and on hillslopes. A key limitation has been the lack of a general model for predicting the size of sediments produced on hillslopes and supplied to channels. Here we present a framework for such a model, as a first step toward building a `geomorphic transport law' that balances mechanistic realism with computational simplicity and is widely applicable across diverse landscapes. The goal is to take as inputs landscape-scale boundary conditions such as lithology, climate and tectonics, and predict the spatial variation in the size distribution of sediments supplied to channels across catchments. The model framework has two components. The first predicts the initial size distribution of particles produced by erosion of bedrock underlying hillslopes, while the second accounts for the effects of physical and chemical weathering during transport down slopes and delivery to channels. The initial size distribution can be related to the spacing and orientation of fractures within bedrock, which depend on the stresses and deformation experienced during exhumation and on rock resistance to fracture propagation. Other controls on initial size include the sizes of mineral grains in crystalline rocks, the sizes of cemented particles in clastic sedimentary rocks, and the potential for characteristic size distributions produced by tree throw, frost cracking, and other erosional processes. To model how weathering processes transform the initial size distribution we consider the effects of erosion rate and the thickness of soil and weathered bedrock on hillslope residence time. Residence time determines the extent of size reduction, for given values of model terms that represent the potential for chemical and physical weathering. Chemical weathering potential
Wegmann, S.F.G.; Franke, K.L.; Hughes, S.; Lewis, R.Q.; Lyons, N.; Paris, P.; Ross, K.; Bauer, J.B.; Witt, A.C.
2011-01-01
The southern Appalachians represent a landscape characterized by locally high topographic relief, steep slopes, and frequent mass movement in the absence of significant tectonic forcing for at least the last 200 Ma. The fundamental processes responsible for landscape evolution in a post-orogenic landscape remain enigmatic. The non-glaciated Cullasaja River basin of south-western North Carolina, with uniform lithology, frequent debris flows, and the availability of high-resolution airborne lidar DEMs, is an ideal natural setting to study landscape evolution in a post-orogenic landscape through the lens of hillslope-channel coupling. This investigation is limited to channels with upslope contributing areas >2.7 km2, a conservative estimate of the transition from fluvial to debris-flow dominated channel processes. Values of normalized hypsometry, hypsometric integral, and mean slope vs elevation are used for 14 tributary basins and the Cullasaja basin as a whole to characterize landscape evolution following upstream knickpoint migration. Results highlight the existence of a transient spatial relationship between knickpoints present along the fluvial network of the Cullasaja basin and adjacent hillslopes. Metrics of topography (relief, slope gradient) and hillslope activity (landslide frequency) exhibit significant downstream increases below the current position of major knickpoints. The transient effect of knickpoint-driven channel incision on basin hillslopes is captured by measuring the relief, mean slope steepness, and mass movement frequency of tributary basins and comparing these results with the distance from major knickpoints along the Cullasaja River. A conceptual model of area-elevation and slope distributions is presented that may be representative of post-orogenic landscape evolution in analogous geologic settings. Importantly, the model explains how knickpoint migration and channel- hillslope coupling is an important factor in tectonically-inactive (i
Kinnell, P. I. A.
2014-11-01
The assumption that runoff is produced uniformly over the eroding area underlies the traditional use of Universal Soil Loss Equation (USLE) and the revised version of it, the RUSLE. However, although the application of the USLE/RUSLE to segments on one dimensional hillslopes and cells on two-dimensional hillslopes is based on the assumption that each segment or cell is spatially uniform, factors such as soil infiltration, and hence runoff production, may vary spatially between segments or cells. Results from equations that focus on taking account of spatially variable runoff when applying the USLE/RUSLE and the USLE-M, the modification of the USLE/RUSLE that replaces the EI30 index by the product of EI30 and the runoff ratio, in hillslopes during erosion events where runoff is not produced uniformly were compared on a hypothetical a 300 m long one-dimensional hillslope with a spatially uniform gradient. Results were produced for situations where all the hillslope was tilled bare fallow and where half of the hillslope was cropped with corn and half was tilled bare fallow. Given that the erosive stress within a segment or cell depends on the volume of surface water flowing through the segment or cell, soil loss can be expected to increase not only with distance from the point where runoff begins but also directly with runoff when it varies about the average for the slope containing the segment or cell. The latter effect was achieved when soil loss was predicted using the USLE-M but not when the USLE/RUSLE slope length factor for a segment using an effective upslope length that varies with the ratio of the upslope runoff coefficient and the runoff coefficient for the slope to the bottom of the segment or cell was used. The USLE-M also predicted deposition to occur in a segment containing corn when an area with tilled bare fallow soil existed immediately upslope of it because the USLE-M models erosion on runoff and soil loss plots as a transport limited system. In a
Mackie, Joshua A.; Natali, Susan M.; Levinton, Jeffrey S.; Sanudo-Wilhelmy, Sergio A.
2007-01-01
This study examines the effectiveness of remediating a well-recognized case of heavy metal pollution at Foundry Cove (FC), Hudson River, New York. This tidal freshwater marsh was polluted with battery-factory wastes (1953-1979) and dredged in 1994-1995. Eight years after remediation, dissolved and particulate metals (Cd, Co, Cu, Pb, Ni, and Ag) were found to be lower than levels in the lower Hudson near New York City. Levels of metals (Co, Ni, Cd) on suspended particles were comparatively high. Concentrations of surface sediment Cd throughout the marsh system remain high, but have decreased both in the dredged and undredged areas: Cd was 2.4-230 mg/kg dw of sediment in 2005 vs. 109-1500 mg/kg in the same area in 1983. The rate of tidal export of Cd from FC has decreased by >300-fold, suggesting that dredging successfully stemmed a major source of Cd to the Hudson River. - Dredging of a hotspot of metal-contaminated sediment is associated with a recognizable local and river-wide decline in cadmium in the Hudson River, New York
Clara Rimondino
2015-01-01
Full Text Available The muddy bottoms of inner Potter Cove, King George Island (Isla 25 de Mayo, South Shetlands, Antarctica, show a high density and richness of macrobenthic species, particularly ascidians. In other areas, ascidians have been reported to play the role of ecosystem engineers, as they support a significant number of epibionts, increasing benthic diversity. In this study, a total of 21 sessile macro-epibiotic taxa present on the ascidian species Corella antarctica Sluiter, 1905, Cnemidocarpa verrucosa (Lesson, 1830 and Molgula pedunculata Herdman, 1881 were identified, with Bryozoa being the most diverse. There were differences between the three ascidian species in terms of richness, percent cover and diversity of sessile macro-epibionts. The morphological characteristics of the tunic surface, the available area for colonization (and its relation with the age of the basibiont individuals and the pH of the ascidian tunic seem to explain the observed differences. Recent environmental changes in the study area (increase of suspended particulate matter caused by glaciers retreat have been related to observed shifts in the benthic community structure, negatively affecting the abundance and distribution of the studied ascidian species. Considering the diversity of sessile macro-epibionts found on these species, the impact of environmental shifts may be greater than that estimated so far.
Cassel, T.A.V.; Edelstein, R.H.; Blair, P.D.
1978-12-01
The analysis and modeling of investment behavior in the development of hydrothermal electric power facilities are reported. This investment behavior reflects a degree of sensitivity to public policy alternatives concerning taxation and regulation of the resource and its related energy conversion facilities. The objective of the current research is to provide a realistic and theoretically sound means for estimating the impacts of such public policy alternatives. A stochastic simulation model was developed which offers an efficient means for site-specific investment analysis of private sector firms and investors. The results of the first year of work are discussed including the identification, analysis, quantification and modeling of: a decision tree reflecting the sequence of procedures, timing and stochastic elements of hydrothermal resource development projects; investment requirements, expenses and revenues incurred in the exploration, development and utilization of hydrothermal resources for electric power generation; and multiattribute investment decision criteria of the several types of firms in the geothermal industry. An application of the investment model to specific resource sites in the state of Utah is also described. Site specific data for the Known Geothermal Resource Areas of Roosevelt Hot Springs and Cove Fort-Sulphurdale are given together with hypothesized generation capacity growth rates.
Dallmeyer, R.D.; O'Driscoll, C.F.; Hussey, E.M.
1981-01-01
Zircon fractions from the variably deformed and metamorphosed Swift Current granite and host volcanic rocks of the Love Cove Group record individually discordant U-Pb ages with well-defined upper concordia intercept ages of 580 +- 20 and 590 +- 30 Ma, respectively. These are interpreted to be crystallization dates and indicate a late Proterozoic cogmagmatic relationship. Primary hornblende from the pluton record disturbed 40 Ar/ 39 Ar age spectra that suggest postcrystallization argon loss, probably during Acadian (Devonian) regional metamorphism. 40 Ar/ 39 Ar plateau ages of 560-566 Ma are well defined for the hornblende and are interpreted to date times of postmagmatic cooling. The similarity between zircon and hornblende dates suggests relatively rapid postmagmatic cooling. A six-point, Rb-Sr whole-rock isochron age of 548 +- 11 Ma is defined for the pluton. The slight discordancy of this date in comparison with the zircon and hornblende ages may reflect a minor disturbance of whole-rock isotopic systems during Acadian regional metamorphism. (author)
Herndon, E.; Steinhoefel, G.; Dere, A. L. D.; Sullivan, P. L.
2017-12-01
Streams experience changing hydrologic connectivity to heterogeneous water sources under different flow regimes. It remains unclear how seasonal flow paths link these different sources and regulate concentration-discharge behavior. Previous research at the Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) in central Pennsylvania, USA identified chemostatic solutes (e.g., K, Mg, Na, Cl) whose concentrations varied little across a wide range of discharge values and chemodynamic solutes (e.g., Fe and Mn) whose concentrations decreased sharply with increasing stream discharge. To elucidate inputs to the stream when concentrations of chemodynamic solutes were high, we investigated stream water and shallow groundwater (table remained over a meter below the stream bed along the rest of the channel. We conclude that well water sampled from the upper catchment is young, shallow interflow that upwells to generate metal-rich stream headwaters during the dry season. High concentrations of chemodynamic solutes measured during low discharge occur when metal-rich headwaters are flushed to the catchment outlet during periodic rain events. Interflow during the dry season originates from water that infiltrates through organic-rich swales; thus, metals in the stream at low flow are ultimately derived from convergent hillslopes where biological processes have concentrated chemodynamic elements. We infer that chemodynamic solutes are diluted at high discharge due to increased flow through planar hillslopes and inputs from regional groundwater that rises to enter the stream. This study highlights how spatially heterogeneous biogeochemistry and seasonally variable flow paths regulate concentration-discharge behavior within catchments.
Hudek, C.; Sterk, Geert; van Beek, Rens L P H; de Jong, Steven M.
2014-01-01
Agricultural activities on hillslopes often cause soil erosion and degradation. Permanent vegetation strips on cultivated slopes could be an effective soil conservation technique to reduce erosion. Previous studies showed that cultivated Mahonia aquifolium can be an effective plant for water erosion
Baartman, Jantiene E. M.; van Gorp, Wouter; Temme, Arnaud J. A. M.; Schoorl, Jeroen M.
Landscape evolution models (LEMs) simulate the three-dimensional development of landscapes over time. Different LEMs have different foci, e.g. erosional behaviour, river dynamics, the fluvial domain, hillslopes or a combination. LEM LAPSUS is a relatively simple cellular model operating on
Rogers, T.; Ohara, N.
2015-12-01
Only few field observations have been implemented using surface and sub-surface trenches to investigate snowmelt-induced hillslope runoffs in mountainous regions. Hillslope trenches may be one of the most direct ways to measure subsurface and overland flow during winter and spring seasons. In July 2014, a 10 meter long trench was constructed with hand tools through glacial till on a south facing hillslope in the Noname Watershed, Medicine Bow National Forest, Wyoming, where heavy equipment and motorized vehicles were restricted. This trench measures subsurface and overland flow for a 610 square meters catchment which has an average slope of 25 degrees. This water-collecting trench is equipped with 4 soil-moisture and temperature sensors to detect the presence of unsaturated flow. Field observations from the trench showed that diurnal oscillation of snowmelt seemed to control the overland flow between the snow and soil surface. The water inputs to the hillslope, including rainfall, evaporation, and snowmelt rates, were estimated from the energy balance computations using the observed meteorological data at the site. Using the water input data, the lateral flow component through the deeper soil or weathered bedrock layer was also quantified by the mass balance in the catchment. This study provides one of key field activities for Wyoming Center for Environmental Hydrology and Geophysics (WyCEHG) project.
T. E. Spittler
1995-01-01
The California Department of Conservation, Division of Mines and Geology (DMG) is submitting this report and accompanying maps to the California Department of Forestry and Fire Protection (CDF) to fulfill Interagency Agreement number 8CA38400, Pilot Monitoring Program -- Geologic Input for the Hillslope Component. Under this agreement, DMG has assisted CDF in the...
Šamonil, Pavel; Daněk, Pavel; Adam, Dušan; Phillips, Jonathan D.
2017-12-01
Tree breakage and uprooting are two possible scenarios of tree death that have differing effects on hillslope processes. In this study we aimed to (i) reveal the long-term structure of the biomechanical effects of trees (BETs) in relation to their radial growth and tree death types in four old-growth temperate forests in four different elevation settings with an altitudinal gradient of 152-1105 m a.s.l., (ii) quantify affected areas and soil volumes associated with the studied BETs in reserves, and (iii) derive a general model of the role of BETs in hillslope processes in central European temperate forests. We analyzed the individual dynamics of circa 55,000 trees in an area of 161 ha within four old-growth forests over 3-4 decades. Basal tree censuses established in all sites in the 1970s and repeated tree censuses in the 1990s and 2000s provided detailed information about the radial growth of each tree of DBH ≥ 10 cm as well as about types of tree death. We focused on the quantification of: (i) surviving still-living trees, (ii) new recruits, (iii) standing dead trees, (iv) uprooted trees, and (v) broken trees. Frequencies of phenomena were related to affected areas and volumes of soil using individual statistical models. The elevation contrasts were a significant factor in the structure of BETs. Differences between sites increased from frequencies of events through affected areas to volumes of soil associated with BETs. An average 2.7 m3 ha-1 year-1 was associated with all BETs of the living and dying trees in lowlands, while there was an average of 7.8 m3 ha-1 year-1 in the highest mountain site. Differences were caused mainly by the effects of dying trees. BETs associated with dead trees were 7-8 times larger in the mountains. Effects of dying trees and particularly treethrows represented about 70% of all BETs at both mountain sites, while it was 58% at the highland site and only 32% at the lowland site. Our results show a more significant role of BETs in
The role of trees in the geomorphic system of forested hillslopes — A review
Pawlik, Łukasz
2013-11-01
Forested hillslopes form a special geoecosystem, an environment of geomorphic processes that depend strongly on forest ecology, including the growth and decay of trees, changes in structure, disturbances and other fluctuations. Hence, the following various functions of trees are reviewed here: their role in both biomechanical and biochemical weathering, as well as their importance for the hillslope geomorphic subsystem and for transport of soil material via tree uprooting and root growth. Special attention is paid to tree uprooting, a process considered the most efficient and most frequent biogeomorphological indicator of bio-physical activity within forest in complex terrain. Trees have varied implications for soil formation in different environments (boreal to tropical forests) and altitudes. In this paper an attempt has been made to emphasize how trees not only modulate geomorphic processes, but also how they act as a direct or indirect agent of microrelief formation, the most striking example of which being widespread and long-lasting pit-and-mound microtopography. Based on the analyzed literature it seems that some problems attributed to forest ecology can have a fundamental effect on forested hillslope dynamics, a relationship which points to the need for its integration and interpretation within the field of geomorphology. The biology of individual trees has a key influence on the development of e.g. rock faces, weathering front migration and changes in the soil biomantle within upper and lower forest belts. Additionally, forms and sediments depend largely on the horizontal and vertical extent, volume and structure of root systems, as well as on active processes taking place in the root zone and rhizosphere. Furthermore, although trees to a large extent stabilize slope surfaces, their presence can also have a dual effect on slope stability due to tree uprooting, a process which in some circumstances can trigger mass movements (e.g. debris avalanches). So far
Simonds, F. William; Swarzenski, Peter W.; Rosenberry, Donald O.; Reich, Christopher D.; Paulson, Anthony J.
2008-01-01
field investigations show that ground-water discharge into the Lynch Cove area of Hood Canal is highly dynamic and strongly affected by the large tidal range. In areas with a steep shoreline and steep hydraulic gradient, ground-water discharge is spatially concentrated in or near the intertidal zone, with increased discharge during low tide. Topographically flat areas with weak hydraulic gradients had more spatial variability, including larger areas of seawater recirculation and more widely dispersed discharge. Measured total-dissolved-nitrogen concentrations in ground water ranged from below detection limits to 2.29 milligrams per liter and the total load entering Lynch Cove was estimated to be approximately 98 ? 10.3 metric tons per year (MT/yr). This estimate is based on net freshwater seepage rates from Lee-type seepage meter measurements and can be compared to estimates derived from geochemical tracer mass balance estimates (radon and radium) of 231 to 749 MT/yr, and previous water-mass-balance estimates (14 to 47 MT/ yr). Uncertainty in these loading estimates is introduced by complex biogeochemical cycles of relevant nutrient species, the representativeness of measurement sites, and by energetic dynamics at the coastal aquifer-seawater interface caused by tidal forcing.
Suwono.
1978-01-01
A linear gate providing a variable gate duration from 0,40μsec to 4μsec was developed. The electronic circuity consists of a linear circuit and an enable circuit. The input signal can be either unipolar or bipolar. If the input signal is bipolar, the negative portion will be filtered. The operation of the linear gate is controlled by the application of a positive enable pulse. (author)
Vretenar, M
2014-01-01
The main features of radio-frequency linear accelerators are introduced, reviewing the different types of accelerating structures and presenting the main characteristics aspects of linac beam dynamics
Hillslope run-off thresholds with shrink–swell clay soils
Stewart, Ryan D.; Abou Najm, Majdi R.; Rupp, David E.; Lane, John W.; Uribe, Hamil C.; Arumí, José Luis; Selker, John S.
2015-01-01
Irrigation experiments on 12 instrumented field plots were used to assess the impact of dynamic soil crack networks on infiltration and run-off. During applications of intensity similar to a heavy rainstorm, water was seen being preferentially delivered within the soil profile. However, run-off was not observed until soil water content of the profile reached field capacity, and the apertures of surface-connected cracks had closed >60%. Electrical resistivity measurements suggested that subsurface cracks persisted and enhanced lateral transport, even in wet conditions. Likewise, single-ring infiltration measurements taken before and after irrigation indicated that infiltration remained an important component of the water budget at high soil water content values, despite apparent surface sealing. Overall, although the wetting and sealing of the soil profile showed considerable complexity, an emergent property at the hillslope scale was observed: all of the plots demonstrated a strikingly similar threshold run-off response to the cumulative precipitation amount.
HIS Design: Big Data that Supports Hydrologic Modeling from Continental to Hillslope Scales
Rasmussen, T. C.; Deemy, J. B.; Younger, S. E.; Kirk, S. E.; Brockman, L. E.
2016-12-01
Analogous to Google Maps, hydrologic data, information, and knowledge resolve differently depending upon the spatial and temporal scales of interest. We show how a multi-scale hydrologic information system (HIS) can be designed and populated for a broad range of spatial (e.g., hillslope, local, regional, continental) and temporal (e.g., current, recent, historic, geologic) scales. Surface and subsurface hydrologic and transport processes are assumed to be scale-dependent, requiring unique governing equations and parameters at each scale. This robust and flexible framework is designed to meet the inventory, monitoring, and management needs of multiple federal agencies (i.e., Forest Service, National Park Service, Fish and Wildlife Service, National Wildlife Reserves). Multi-scale HIS examples are provided using Geographic Information Systems (GIS) for the Southeastern US.
Linearization Method and Linear Complexity
Tanaka, Hidema
We focus on the relationship between the linearization method and linear complexity and show that the linearization method is another effective technique for calculating linear complexity. We analyze its effectiveness by comparing with the logic circuit method. We compare the relevant conditions and necessary computational cost with those of the Berlekamp-Massey algorithm and the Games-Chan algorithm. The significant property of a linearization method is that it needs no output sequence from a pseudo-random number generator (PRNG) because it calculates linear complexity using the algebraic expression of its algorithm. When a PRNG has n [bit] stages (registers or internal states), the necessary computational cost is smaller than O(2n). On the other hand, the Berlekamp-Massey algorithm needs O(N2) where N(≅2n) denotes period. Since existing methods calculate using the output sequence, an initial value of PRNG influences a resultant value of linear complexity. Therefore, a linear complexity is generally given as an estimate value. On the other hand, a linearization method calculates from an algorithm of PRNG, it can determine the lower bound of linear complexity.
Scheliga, Bernhard; Tetzlaff, Doerthe; Nuetzmann, Gunnar; Soulsby, Chris
2016-04-01
Groundwater-surface water dynamics play an important role in runoff generation and the hydrologic connectivity between hillslopes and streams. Here, we present findings from a suite of integrated, empirical approaches to increase our understanding of groundwater-surface water interlinkages in a 3.2 km ^ 2 experimental catchment in the Scottish Highlands. The montane catchment is mainly underlain by granite and has extensive (70%) cover of glacial drift deposits which are up to 40 m deep and form the main aquifer in the catchment. Flat valley bottom areas fringe the stream channel and are characterised by peaty soils (0.5-4 m deep) which cover about 10% of the catchment and receive drainage from upslope areas. The transition between the hillslopes and riparian zone forms a critical interface for groundwater-surface water interactions that controls both the dynamics of riparian saturation and stream flow generation. We nested observations using wells to assess the groundwater - surface water transition, LiDAR surveys to explore the influence of micro-topography on shallow groundwater efflux and riparian wells to examine the magnitude and flux rates of deeper groundwater sources. We also used electrical resistivity surveys to assess the architecture and storage properties of drift aquifers. Finally, we used isotopic tracers to differentiate recharge sources and associated residence times as well as quantifying how groundwater dynamics affect stream flow. These new data have provided a novel conceptual framework for local groundwater - surface water exchange that is informing the development of new deterministic models for the site.
Said-Houari, Belkacem
2017-01-01
This self-contained, clearly written textbook on linear algebra is easily accessible for students. It begins with the simple linear equation and generalizes several notions from this equation for the system of linear equations and introduces the main ideas using matrices. It then offers a detailed chapter on determinants and introduces the main ideas with detailed proofs. The third chapter introduces the Euclidean spaces using very simple geometric ideas and discusses various major inequalities and identities. These ideas offer a solid basis for understanding general Hilbert spaces in functional analysis. The following two chapters address general vector spaces, including some rigorous proofs to all the main results, and linear transformation: areas that are ignored or are poorly explained in many textbooks. Chapter 6 introduces the idea of matrices using linear transformation, which is easier to understand than the usual theory of matrices approach. The final two chapters are more advanced, introducing t...
Spatio-temporal variability of soil moisture (') is a challenge that remains to be better understood. A trade-off exists between spatial coverage and temporal resolution when using the manual and real-time ' monitoring methods. This restricted the comprehensive and intensive examination of ' dynamic...
Stoll, R R
1968-01-01
Linear Algebra is intended to be used as a text for a one-semester course in linear algebra at the undergraduate level. The treatment of the subject will be both useful to students of mathematics and those interested primarily in applications of the theory. The major prerequisite for mastering the material is the readiness of the student to reason abstractly. Specifically, this calls for an understanding of the fact that axioms are assumptions and that theorems are logical consequences of one or more axioms. Familiarity with calculus and linear differential equations is required for understand
Sorensen, P.; Beller, H. R.; Bill, M.; Bouskill, N.; Brodie, E.; Chakraborty, R.; Conrad, M. E.; Karaoz, U.; Polussa, A.; Steltzer, H.; Wang, S.; Williams, K. H.; Wilmer, C.; Wu, Y.
2017-12-01
Nitrogen export from mountainous watersheds is a product of multiple interactions among hydrological processes and soil-microbial-plant feedbacks along the continuum from terrestrial to aquatic environments. In snow-dominated systems, like the East River Watershed (CO), seasonal processes such as snowmelt exert significant influence on the annual hydrologic cycle and may also link spatially distinct catchment subsystems, such as hillslope and adjoining riparian floodplains. Further, snowmelt is occurring earlier each year and this is predicted to result in a temporal asynchrony between historically coupled microbial nutrient release and plant nutrient demand in spring, with the potential to increase N export from the East River Watershed. Here we summarize biogeochemical data collected along a hillslope-to-riparian floodplain transect at the East River site. Starting in Fall 2016, we sampled soils at 3 depths and measured dissolved pools of soil nutrients (e.g., NH4+, NO3-, DOC, P), microbial biomass CN, and microbial community composition over a seasonal time course, through periods of snow accumulation, snowmelt, and plant senescence. Soil moisture content in the top 5 cm of floodplain soils was nearly 4X greater across sampling dates, coinciding with 2X greater microbial biomass C, larger extractable pools of NH4+, and smaller pools of NO3- in floodplain vs. hillslope soils. These results suggest that microbially mediated redox processes played an important role in N cycling along the transect. Hillslope vs. floodplain location also appeared to be a key factor that differentiated soil microbial communities (e.g., a more important factor than seasonality or soil depth or type). Snow accumulation and snowmelt exerted substantial influence on soil biogeochemistry. For example, microbial biomass accumulation increased about 2X beneath the winter snowpack. Snowmelt resulted in a precipitous crash in the microbial population, with 2.5X reductions in floodplain and 2X
Daglio, Yasmin; Sacristán, Hernán; Ansaldo, Martín; Rodríguez, María C.
2018-03-01
Biofilms were allowed to develop on ceramic tiles placed in closed containers on the shore of Potter Cove, 25 de Mayo (King George) Island. Water pumping from the cove inside the containers extended for 25 days. Diatoms were the dominant microalgae in these biofilms, which were removed from a set of tiles to a) characterize the extracellular mucilage, b) carry out floristic determination and c) perform grazing experiments with the limpet Nacella concinna. Biofilms mucilaginous matrix consisted of proteins and carbohydrates. Room temperature aqueous extraction of the freeze-dried material rendered a fraction enriched in the storage glucan chrysolaminarin, its identity confirmed by methylation structural analyses. Hot water extracted products showed greater heterogeneity in monosaccharide composition, including glucose, mannose, galactose, fucose, xylose and rhamnose. Diatom identification revealed that Pseudogomphonema kamtschaticum was the dominant species followed by several Navicula species, Nitzschia pellucida and Synedra kerguelensis. Photographical survey of colonized tiles placed in glass flasks together with a specimen of Nacella concinna exhibited between 5 and 30% removal of the biofilms coverage after 24 h of exposure to the limpet, suggesting that EPS and chrysolaminarin constitute a C-source for the gastropod.
NONE
2002-09-01
A proposal was made by New Brunswick (NB) Power for the refurbishment of the Coleson Cove generating station, to the Public Utilities Board (PUB). It was determined by the PUB that a requirement existed for 1050 megawatt (MW) of power at Coleson Cove. This document presented a summary of public participation. Two meetings were held in support of the Environmental Impact Assessment (EIA). Several concerns were raised by various groups at both meetings. Some of the issues discussed included: (1) Orimulsion{sup R} fuel, reputed to be the dirtiest fuel in the world, (2) fuel supply, (3) project agenda, (4) project costs and others. It appeared that most of the participants in the public consultation process were against the proposal. It was felt that the emissions of sulphur dioxide and nitrous oxide should be considered in the greater context of reducing present and future emissions of greenhouse gases. The participants recommended that the New Brunswick government support a 400 MW combined cycle natural gas turbine unit instead of the proposal under review. Much opposition to the project concerned the potential degradation of the environment and the health of the citizens. Environmental representatives were concerned since the Solid Waste Management Area would be located in the vicinity of a proposed marine and wildlife sanctuary. Industry representatives were eager for the opportunities offered by the proposal. refs.
Miller, J.F.; Ethington, Raymond L.; Evans, K.R.; Holmer, L.E.; Loch, James D.; Popov, L.E.; Repetski, J.E.; Ripperdan, R.L.; Taylor, John F.
2006-01-01
We propose a candidate for the Global Standard Stratotype-section and Point (GSSP) for the base of the highest stage of the Furongian Series of the Cambrian System. The section is at Lawson Cove in the Ibex area of Millard County, Utah, USA. The marker horizon is the first appearance datum (FAD) of the conodont Cordylodus andresi Viira et Sergeyeva in Kaljo et al. [Kaljo, D., Borovko, N., Heinsalu, H., Khazanovich, K., Mens, K., Popov, L., Sergeyeva, S., Sobolevskaya, R., Viira, V., 1986. The Cambrian-Ordovician boundary in the Baltic-Ladoga clint area (North Estonia and Leningrad Region, USSR). Eesti NSV Teaduste Akadeemia Toimetised. Geologia 35, 97-108]. At this section and elsewhere this horizon also is the FAD of the trilobite Eurekia apopsis (Winston et Nicholls, 1967). This conodont characterizes the base of the Cordylodus proavus Zone, which has been recognized in many parts of the world. This trilobite characterizes the base of the Eurekia apopsis Zone, which has been recognized in many parts of North America. The proposed boundary is 46.7 m above the base of the Lava Dam Member of the Notch Peak Formation at the Lawson Cove section. Brachiopods, sequence stratigraphy, and carbon-isotope geochemistry are other tools that characterize this horizon and allow it to be recognized in other areas. ?? 2006 Nanjing Institute of Geology and Palaeontology, CAS.
Solow, Daniel
2014-01-01
This text covers the basic theory and computation for a first course in linear programming, including substantial material on mathematical proof techniques and sophisticated computation methods. Includes Appendix on using Excel. 1984 edition.
Liesen, Jörg
2015-01-01
This self-contained textbook takes a matrix-oriented approach to linear algebra and presents a complete theory, including all details and proofs, culminating in the Jordan canonical form and its proof. Throughout the development, the applicability of the results is highlighted. Additionally, the book presents special topics from applied linear algebra including matrix functions, the singular value decomposition, the Kronecker product and linear matrix equations. The matrix-oriented approach to linear algebra leads to a better intuition and a deeper understanding of the abstract concepts, and therefore simplifies their use in real world applications. Some of these applications are presented in detailed examples. In several ‘MATLAB-Minutes’ students can comprehend the concepts and results using computational experiments. Necessary basics for the use of MATLAB are presented in a short introduction. Students can also actively work with the material and practice their mathematical skills in more than 300 exerc...
Berberian, Sterling K
2014-01-01
Introductory treatment covers basic theory of vector spaces and linear maps - dimension, determinants, eigenvalues, and eigenvectors - plus more advanced topics such as the study of canonical forms for matrices. 1992 edition.
Searle, Shayle R
2012-01-01
This 1971 classic on linear models is once again available--as a Wiley Classics Library Edition. It features material that can be understood by any statistician who understands matrix algebra and basic statistical methods.
Christofilos, N.C.; Polk, I.J.
1959-02-17
Improvements in linear particle accelerators are described. A drift tube system for a linear ion accelerator reduces gap capacity between adjacent drift tube ends. This is accomplished by reducing the ratio of the diameter of the drift tube to the diameter of the resonant cavity. Concentration of magnetic field intensity at the longitudinal midpoint of the external sunface of each drift tube is reduced by increasing the external drift tube diameter at the longitudinal center region.
Cai, J.; Yan, E.; Yeh, T. C. J.
2015-12-01
Pore-water pressure in a hillslope is a critical control of its stability. The main objective of this paper is to introduce a first-order moment analysis to investigate the pressure head variability within a hypothetical hillslope, induced by steady rainfall infiltration. This approach accounts for the uncertainties and spatial variation of the hydraulic conductivity, and is based on a first-order Taylor approximation of pressure perturbations calculated by a variably saturated, finite element flow model. Using this approach, the effects of variance (σ2lnKs) and spatial structure anisotropy (λh/λv) of natural logarithm of saturated hydraulic conductivity, and normalized vertical infiltration flux (q/ks) on the hillslope pore-water pressure are evaluated. We found that the responses of pressure head variability (σ2p) are quite different between unsaturated region and saturated region divided by the phreatic surface. Above the phreatic surface, a higher variability in pressure head is obtained from a higher σ2lnKs, a higher λh/λv and a smaller q/ks; while below the phreatic surface, a higher σ2lnKs, a lower λh/λv or a larger q/ks would lead to a higher variability in pressure head, and greater range of fluctuation of the phreatic surface within the hillslope. σ2lnKs has greatest impact on σ2p within the slope and λh/λv has smallest impact. All three variables have greater influence on maximum σ2p within the saturated region below the phreatic surface than that within the unsaturated region above the phreatic surface. The results obtained from this study are useful to understand the influence of hydraulic conductivity variations on slope seepage and stability under different slope conditions and material spatial distributions.
Pilz, Tobias; Francke, Till; Bronstert, Axel
2017-08-01
The characteristics of a landscape pose essential factors for hydrological processes. Therefore, an adequate representation of the landscape of a catchment in hydrological models is vital. However, many of such models exist differing, amongst others, in spatial concept and discretisation. The latter constitutes an essential pre-processing step, for which many different algorithms along with numerous software implementations exist. In that context, existing solutions are often model specific, commercial, or depend on commercial back-end software, and allow only a limited or no workflow automation at all. Consequently, a new package for the scientific software and scripting environment R, called lumpR, was developed. lumpR employs an algorithm for hillslope-based landscape discretisation directed to large-scale application via a hierarchical multi-scale approach. The package addresses existing limitations as it is free and open source, easily extendible to other hydrological models, and the workflow can be fully automated. Moreover, it is user-friendly as the direct coupling to a GIS allows for immediate visual inspection and manual adjustment. Sufficient control is furthermore retained via parameter specification and the option to include expert knowledge. Conversely, completely automatic operation also allows for extensive analysis of aspects related to landscape discretisation. In a case study, the application of the package is presented. A sensitivity analysis of the most important discretisation parameters demonstrates its efficient workflow automation. Considering multiple streamflow metrics, the employed model proved reasonably robust to the discretisation parameters. However, parameters determining the sizes of subbasins and hillslopes proved to be more important than the others, including the number of representative hillslopes, the number of attributes employed for the lumping algorithm, and the number of sub-discretisations of the representative hillslopes.
Masaoka, Naoya; Kosugi, Ken'ichirou; Yamakawa, Yosuke; Mizuyama, Takahisa; Tsutsumi, Daizo
2013-04-01
Heterogeneous hydrological properties in a foot slope area of mountainous hillslopes should be assessed to understand hydrological phenomena and their effects on discharge and sediment transport. In this study, we analyzed the high-resolution and three-dimensional water movement data to clarify the hydrological process, including heterogeneous phenomena, in detail. We continuously monitored the soil matric pressure head, psi, using 111 tensiometers installed at grid intervals of approximately 1 meter within the soil mantle at the study hillslope. Under a no-rainfall condition, the existence of perennial groundwater seepage flow was detected by exfiltration flux and temporal psi waveforms, which showed delayed responses, only to heavy storm events, and gradual recession limbs. The seepage water spread in the downslope direction and supplied water constantly to the lower section of the slope. At some points in the center of the slope, a perched saturated area was detected in the middle of soil layer, while psi exhibited negative values above the bedrock surface. These phenomena could be inferred partly from the bedrock topography and the distribution of soil hydraulic conductivity assumed from the result of penetration test. At the peak of a rainfall event, on the other hand, continuous high pressure zones (i.e., psi > 50 cmH2O) were generated in the right and left sections of the slope. Both of these high pressure zones converged at the lower region, showing a sharp psi spike up to 100 cmH2O. Along the high pressure zones, flux vectors showed large values and water exfiltration, indicating the occurrence of preferential flow. Moreover, the preferential flow occurred within the area beneath the perched water, indicating the existence of a weathered bedrock layer. This layer had low permeability, which prevented the vertical infiltration of water in the upper part of the layer, but had high permeability as a result of the fractures distributed heterogeneously inside
Adapting SWAT hillslope erosion model to predict sediment concentrations and yields in large Basins.
Vigiak, Olga; Malagó, Anna; Bouraoui, Fayçal; Vanmaercke, Matthias; Poesen, Jean
2015-12-15
The Soil and Water Assessment Tool (SWAT) is used worldwide for water quality assessment and planning. This paper aimed to assess and adapt SWAT hillslope sediment yield model (Modified Universal Soil Loss Equation, MUSLE) for applications in large basins, i.e. when spatial data is coarse and model units are large; and to develop a robust sediment calibration method for large regions. The Upper Danube Basin (132,000km(2)) was used as case study representative of large European Basins. The MUSLE was modified to reduce sensitivity of sediment yields to the Hydrologic Response Unit (HRU) size, and to identify appropriate algorithms for estimating hillslope length (L) and slope-length factor (LS). HRUs gross erosion was broadly calibrated against plot data and soil erosion map estimates. Next, mean annual SWAT suspended sediment concentrations (SSC, mg/L) were calibrated and validated against SSC data at 55 gauging stations (622 station-years). SWAT annual specific sediment yields in subbasin reaches (RSSY, t/km(2)/year) were compared to yields measured at 33 gauging stations (87station-years). The best SWAT configuration combined a MUSLE equation modified by the introduction of a threshold area of 0.01km(2) where L and LS were estimated with flow accumulation algorithms. For this configuration, the SSC residual interquartile was less than +/-15mg/L both for the calibration (1995-2004) and the validation (2005-2009) periods. The mean SSC percent bias for 1995-2009 was 24%. RSSY residual interquartile was within +/-10t/km(2)/year, with a mean RSSY percent bias of 12%. Residuals showed no bias with respect to drainage area, slope, or spatial distribution. The use of multiple data types at multiple sites enabled robust simulation of sediment concentrations and yields of the region. The MUSLE modifications are recommended for use in large basins. Based on SWAT simulations, we present a sediment budget for the Upper Danube Basin. Copyright © 2015. Published by Elsevier B.V.
Olive, David J
2017-01-01
This text covers both multiple linear regression and some experimental design models. The text uses the response plot to visualize the model and to detect outliers, does not assume that the error distribution has a known parametric distribution, develops prediction intervals that work when the error distribution is unknown, suggests bootstrap hypothesis tests that may be useful for inference after variable selection, and develops prediction regions and large sample theory for the multivariate linear regression model that has m response variables. A relationship between multivariate prediction regions and confidence regions provides a simple way to bootstrap confidence regions. These confidence regions often provide a practical method for testing hypotheses. There is also a chapter on generalized linear models and generalized additive models. There are many R functions to produce response and residual plots, to simulate prediction intervals and hypothesis tests, to detect outliers, and to choose response trans...
Alcaraz, J.
2001-01-01
After several years of study e''+ e''- linear colliders in the TeV range have emerged as the major and optimal high-energy physics projects for the post-LHC era. These notes summarize the present status form the main accelerator and detector features to their physics potential. The LHC era. These notes summarize the present status, from the main accelerator and detector features to their physics potential. The LHC is expected to provide first discoveries in the new energy domain, whereas an e''+ e''- linear collider in the 500 GeV-1 TeV will be able to complement it to an unprecedented level of precision in any possible areas: Higgs, signals beyond the SM and electroweak measurements. It is evident that the Linear Collider program will constitute a major step in the understanding of the nature of the new physics beyond the Standard Model. (Author) 22 refs
Edwards, Harold M
1995-01-01
In his new undergraduate textbook, Harold M Edwards proposes a radically new and thoroughly algorithmic approach to linear algebra Originally inspired by the constructive philosophy of mathematics championed in the 19th century by Leopold Kronecker, the approach is well suited to students in the computer-dominated late 20th century Each proof is an algorithm described in English that can be translated into the computer language the class is using and put to work solving problems and generating new examples, making the study of linear algebra a truly interactive experience Designed for a one-semester course, this text adopts an algorithmic approach to linear algebra giving the student many examples to work through and copious exercises to test their skills and extend their knowledge of the subject Students at all levels will find much interactive instruction in this text while teachers will find stimulating examples and methods of approach to the subject
Xiaonan Shi Fan Zhang
2012-01-01
Full Text Available Sediment concentration in hill-slope runoff is an important index for soil erosion. Developing a reliable and portable measuring system of sediment concentration is a core issue for soil and water conservation study, especially for the Tibetan Plateau under unfavorable climate and terrain conditions for field investigation. Challenges include uneven distribution of sediment across a runoff section as well as difficulty in detecting a wide range of particle sizes. An electrolyte tracer, with the advantage of uniform distribution and its widely used electric-conductivity sensor, can avoid the problems of direct measurement of sediment. A new measurement method of sediment concentration in runoff with an electrolyte tracer is proposed based on a premise that sediment concentration is closely correlated with hydrodynamic dispersion coefficient of solute in runoff. In this study, an experiment system of hill-slope runoff with an electrolyte tracer and sediments is first designed. Second, two model parameters in the advective-dispersive equation of solute transport, flow velocity and diffusion coefficient, are inversely estimated by calibrating the observed concentrations of an electrolyte tracer. And third, the relationship between sediment concentrations and hydrodynamic dispersion coefficients are defined through specified regression. As a result, a measurement system of sediment concentration in hill-slope runoff with an electrolyte tracer is primarily established by integrating the relationship of variables, experiment system, and model theory.
Liu, Jun'e; Wang, Zhanli; Li, Yuanyuan
2017-12-22
Raindrops disperse large soil aggregates into smaller particles, which can clog soil pores, cause soil crusting, reduce rainfall infiltration and increase soil loss. It was found that natural polymer derivatives were effective in improving soil physical properties and decreasing soil erosion on an experimental loess hillslope. This study investigated the effect of new natural polymer derivatives (Jag S and Jag C162) on soil properties, rainfall infiltration and sediment yield at four rates of sprayed polymers (0, 1, 3 and 5 g/m²), three rainfall intensities (1, 1.5 and 2 mm/min) and a slope gradient of 15° with a silt loam soil through simulated rain. The results showed that both Jag S and Jag C162 significantly increased the shear strength and improved the aggregates composition of the soil surface. The water-stable soil aggregates >0.25 mm increased from 9% to 50% with increasing rates of Jag S and Jag C162. Jag S and Jag C162 also effectively increased rainfall infiltration and final infiltration rate, and reduced erosion compared to controls without natural polymer derivatives added. However, higher rates of Jag S produced lower infiltration rates. Although both Jag S and Jag C162 effectively influenced soil physical properties and erosion, the effect of Jag C162 was more significant than that of Jag S.
Jun’e Liu
2017-12-01
Full Text Available Raindrops disperse large soil aggregates into smaller particles, which can clog soil pores, cause soil crusting, reduce rainfall infiltration and increase soil loss. It was found that natural polymer derivatives were effective in improving soil physical properties and decreasing soil erosion on an experimental loess hillslope. This study investigated the effect of new natural polymer derivatives (Jag S and Jag C162 on soil properties, rainfall infiltration and sediment yield at four rates of sprayed polymers (0, 1, 3 and 5 g/m2, three rainfall intensities (1, 1.5 and 2 mm/min and a slope gradient of 15° with a silt loam soil through simulated rain. The results showed that both Jag S and Jag C162 significantly increased the shear strength and improved the aggregates composition of the soil surface. The water-stable soil aggregates >0.25 mm increased from 9% to 50% with increasing rates of Jag S and Jag C162. Jag S and Jag C162 also effectively increased rainfall infiltration and final infiltration rate, and reduced erosion compared to controls without natural polymer derivatives added. However, higher rates of Jag S produced lower infiltration rates. Although both Jag S and Jag C162 effectively influenced soil physical properties and erosion, the effect of Jag C162 was more significant than that of Jag S.
Liu, Jun’e; Wang, Zhanli; Li, Yuanyuan
2017-01-01
Raindrops disperse large soil aggregates into smaller particles, which can clog soil pores, cause soil crusting, reduce rainfall infiltration and increase soil loss. It was found that natural polymer derivatives were effective in improving soil physical properties and decreasing soil erosion on an experimental loess hillslope. This study investigated the effect of new natural polymer derivatives (Jag S and Jag C162) on soil properties, rainfall infiltration and sediment yield at four rates of sprayed polymers (0, 1, 3 and 5 g/m2), three rainfall intensities (1, 1.5 and 2 mm/min) and a slope gradient of 15° with a silt loam soil through simulated rain. The results showed that both Jag S and Jag C162 significantly increased the shear strength and improved the aggregates composition of the soil surface. The water-stable soil aggregates >0.25 mm increased from 9% to 50% with increasing rates of Jag S and Jag C162. Jag S and Jag C162 also effectively increased rainfall infiltration and final infiltration rate, and reduced erosion compared to controls without natural polymer derivatives added. However, higher rates of Jag S produced lower infiltration rates. Although both Jag S and Jag C162 effectively influenced soil physical properties and erosion, the effect of Jag C162 was more significant than that of Jag S. PMID:29271899
Slope-velocity equilibrium and evolution of surface roughness on a stony hillslope
Nearing, Mark A.; Polyakov, Viktor O.; Nichols, Mary H.; Hernandez, Mariano; Li, Li; Zhao, Ying; Armendariz, Gerardo
2017-06-01
Slope-velocity equilibrium is hypothesized as a state that evolves naturally over time due to the interaction between overland flow and surface morphology, wherein steeper areas develop a relative increase in physical and hydraulic roughness such that flow velocity is a unique function of overland flow rate independent of slope gradient. This study tests this hypothesis under controlled conditions. Artificial rainfall was applied to 2 m by 6 m plots at 5, 12, and 20 % slope gradients. A series of simulations were made with two replications for each treatment with measurements of runoff rate, velocity, rock cover, and surface roughness. Velocities measured at the end of each experiment were a unique function of discharge rates, independent of slope gradient or rainfall intensity. Physical surface roughness was greater at steeper slopes. The data clearly showed that there was no unique hydraulic coefficient for a given slope, surface condition, or rainfall rate, with hydraulic roughness greater at steeper slopes and lower intensities. This study supports the hypothesis of slope-velocity equilibrium, implying that use of hydraulic equations, such as Chezy and Manning, in hillslope-scale runoff models is problematic because the coefficients vary with both slope and rainfall intensity.
Plant functional coexistence and influence on the eco-hydrologic response of semiarid hillslopes
Soltanjalili, Mohammadjafar; Saco, Patricia M.; Willgoose, Garry
2016-04-01
Through its influence on rainfall-runoff and erosion-deposition processes, vegetation remarkably regulates different aspects of landscape processes. Here, the influence of different plant functional dynamics on the coexistence of different species in arid and semi-arid regions with banded vegetation patterns is investigated. Simulations capture the coevolution and coexistence of two different species interacting with hydrology in hillslopes with gentle slopes. The dynamic vegetation model simulates the dynamics of overland runoff, soil moisture, facilitation mechanisms (evaporation reduction through shading and enhanced infiltration by vegetation), local and non-local seed dispersal, competition through water uptake and changes in the biomass of the two species. Here for simplicity the two species are assumed to use water from the same soil depth. Results of the coexistence of the two species capture differences in facilitation-competition interactions caused by specific types of vegetation with varying hydrologic traits. The results illustrate that the dominance of facilitation or competition feedbacks which determine either the coexistence of the two species or survival of only one of them strongly depends on the characteristics and hydrologic traits of the coexisting species and the severity of water stresses. We therefore argue that our results should stimulate further research into the role of interspecific and intraspecific feedbacks between different plant species and specifically the influence of the resulting vegetation community on landform evolution processes.
Blackburn, M.; Ledesma, José L. J.; Näsholm, Torgny; Laudon, Hjalmar; Sponseller, Ryan A.
2017-02-01
Catchment science has long held that the chemistry of small streams reflects the landscapes they drain. However, understanding the contribution of different landscape units to stream chemistry remains a challenge which frequently limits our understanding of export dynamics. For limiting nutrients such as nitrogen (N), an implicit assumption is that the most spatially extensive landscape units (e.g., uplands) act as the primary sources to surface waters, while near-stream zones function more often as sinks. These assumptions, based largely on studies in high-gradient systems or in regions with elevated inputs of anthropogenic N, may not apply to low-gradient, nutrient-poor, and peat-rich catchments characteristic of many northern ecosystems. We quantified patterns of N mobilization along a hillslope transect in a northern boreal catchment to assess the extent to which organic matter-rich riparian soils regulate the flux of N to streams. Contrary to the prevailing view of riparian functioning, we found that near-stream, organic soils supported concentrations and fluxes of ammonium (NH4+) and dissolved organic nitrogen that were much higher than the contributing upslope forest soils. These results suggest that stream N chemistry is connected to N mobilization and mineralization within the riparian zone rather than the wider landscape. Results further suggest that water table fluctuation in near-surface riparian soils may promote elevated rates of net N mineralization in these landscapes.
Barnes, R. T.; Gilbertson, A.; Maxwell, K.
2017-12-01
Disturbance strongly regulates material and energy flows, changing ecosystem pattern and process. An increase in the size and severity of fire, particularly in the Intermountain West, over the last several decades is expected to continue due to a warming climate. Predicting how fire will alter the net ecosystem carbon balance requires us to understand how carbon is stored, processed, and transferred. Here we present results from paired watersheds focused on five 2002 severe fires in Colorado to examine how organic matter is processed along the hillslope and within the stream. Comparing soil samples and water extractable organic matter (WEOM) between burned and unburned sites illustrates the impact of fire: burned soils have 50% organic matter (OM) content as unburned soils, regardless of geomorphic position. While a smaller pool, soil OM (SOM) in burned sites is more susceptible to microbial degradation (pmineral rich, organic poor, portion of the soil. Interestingly, the systematic shifts in OM amounts and quality (as measured by SUVA, E2:E3, and fluorescence) within the terrestrial system in response to fire, are not seen in stream exports. As such, while there are significant relationships (p<0.05) between stream DOM quality, DOM bioavailability, and stream metabolism, burned watersheds are not exporting DOM that is more bioavailable. In addition, despite different terrestrial OM pools, burned and unburned watersheds export statistically similar amounts of DOM per unit area, suggesting that a larger fraction of OM is transferred from the terrestrial to aquatic ecosystem within fire affected landscapes.
James, A.L.; McDonnell, Jeffery J.; Tromp-Van Meerveld, I.; Peters, N.E.
2010-01-01
As a fundamental unit of the landscape, hillslopes are studied for their retention and release of water and nutrients across a wide range of ecosystems. The understanding of these near-surface processes is relevant to issues of runoff generation, groundwater-surface water interactions, catchment export of nutrients, dissolved organic carbon, contaminants (e.g. mercury) and ultimately surface water health. We develop a 3-D physics-based representation of the Panola Mountain Research Watershed experimental hillslope using the TOUGH2 sub-surface flow and transport simulator. A recent investigation of sub-surface flow within this experimental hillslope has generated important knowledge of threshold rainfall-runoff response and its relation to patterns of transient water table development. This work has identified components of the 3-D sub-surface, such as bedrock topography, that contribute to changing connectivity in saturated zones and the generation of sub-surface stormflow. Here, we test the ability of a 3-D hillslope model (both calibrated and uncalibrated) to simulate forested hillslope rainfall-runoff response and internal transient sub-surface stormflow dynamics. We also provide a transparent illustration of physics-based model development, issues of parameterization, examples of model rejection and usefulness of data types (e.g. runoff, mean soil moisture and transient water table depth) to the model enterprise. Our simulations show the inability of an uncalibrated model based on laboratory and field characterization of soil properties and topography to successfully simulate the integrated hydrological response or the distributed water table within the soil profile. Although not an uncommon result, the failure of the field-based characterized model to represent system behaviour is an important challenge that continues to vex scientists at many scales. We focus our attention particularly on examining the influence of bedrock permeability, soil anisotropy and
P. Metcalfe
2018-04-01
Full Text Available Enhanced hillslope storage is utilised in natural flood management in order to retain overland storm run-off and to reduce connectivity between fast surface flow pathways and the channel. Examples include excavated ponds, deepened or bunded accumulation areas, and gullies and ephemeral channels blocked with wooden barriers or debris dams. The performance of large, distributed networks of such measures is poorly understood. Extensive schemes can potentially retain large quantities of run-off, but there are indications that much of their effectiveness can be attributed to desynchronisation of sub-catchment flood waves. Inappropriately sited measures may therefore increase, rather than mitigate, flood risk. Fully distributed hydrodynamic models have been applied in limited studies but introduce significant computational complexity. The longer run times of such models also restrict their use for uncertainty estimation or evaluation of the many potential configurations and storm sequences that may influence the timings and magnitudes of flood waves.Here a simplified overland flow-routing module and semi-distributed representation of enhanced hillslope storage is developed. It is applied to the headwaters of a large rural catchment in Cumbria, UK, where the use of an extensive network of storage features is proposed as a flood mitigation strategy. The models were run within a Monte Carlo framework against data for a 2-month period of extreme flood events that caused significant damage in areas downstream. Acceptable realisations and likelihood weightings were identified using the GLUE uncertainty estimation framework. Behavioural realisations were rerun against the catchment model modified with the addition of the hillslope storage. Three different drainage rate parameters were applied across the network of hillslope storage. The study demonstrates that schemes comprising widely distributed hillslope storage can be modelled effectively within such a
Metcalfe, Peter; Beven, Keith; Hankin, Barry; Lamb, Rob
2018-04-01
Enhanced hillslope storage is utilised in natural flood management in order to retain overland storm run-off and to reduce connectivity between fast surface flow pathways and the channel. Examples include excavated ponds, deepened or bunded accumulation areas, and gullies and ephemeral channels blocked with wooden barriers or debris dams. The performance of large, distributed networks of such measures is poorly understood. Extensive schemes can potentially retain large quantities of run-off, but there are indications that much of their effectiveness can be attributed to desynchronisation of sub-catchment flood waves. Inappropriately sited measures may therefore increase, rather than mitigate, flood risk. Fully distributed hydrodynamic models have been applied in limited studies but introduce significant computational complexity. The longer run times of such models also restrict their use for uncertainty estimation or evaluation of the many potential configurations and storm sequences that may influence the timings and magnitudes of flood waves. Here a simplified overland flow-routing module and semi-distributed representation of enhanced hillslope storage is developed. It is applied to the headwaters of a large rural catchment in Cumbria, UK, where the use of an extensive network of storage features is proposed as a flood mitigation strategy. The models were run within a Monte Carlo framework against data for a 2-month period of extreme flood events that caused significant damage in areas downstream. Acceptable realisations and likelihood weightings were identified using the GLUE uncertainty estimation framework. Behavioural realisations were rerun against the catchment model modified with the addition of the hillslope storage. Three different drainage rate parameters were applied across the network of hillslope storage. The study demonstrates that schemes comprising widely distributed hillslope storage can be modelled effectively within such a reduced complexity
National Oceanic and Atmospheric Administration, Department of Commerce — NGDC builds and distributes high-resolution, coastal digital elevation models (DEMs) that integrate ocean bathymetry and land topography to support NOAA's mission to...
Masselink, Rens; Temme, Arnaud; Giménez, Rafael; Casalí, Javier; Keesstra, Saskia
2017-04-01
Soil erosion from agricultural areas is a large problem, because of off-site effects like the rapid filling of reservoirs. To mitigate the problem of sediments from agricultural areas reaching the channel, reservoirs and other surface waters, it is important to understand hillslope-channel connectivity and catchment connectivity. To determine the functioning of hillslope-channel connectivity and the continuation of transport of these sediments in the channel, it is necessary to obtain data on sediment transport from the hillslopes to the channels. Simultaneously, the factors that influence sediment export out of the catchment need to be studied. For measuring hillslope-channel sediment connectivity, Rare-Earth Oxide (REO) tracers were applied to a hillslope in an agricultural catchment in Navarre, Spain, preceding the winter of 2014-2015. The results showed that during the winter there was no sediment transport from the hillslope to the channel. Analysis of precipitation data showed that total precipitation quantities did not differ much from the mean. However, precipitation intensities were low, causing little sediment mobilisation. To test the implication of the REO results at the catchment scale, two conceptual models for sediment connectivity were assessed using a Random Forest (RF) machine learning method. One model proposes that small events provide sediment for large events, while the other proposes that only large events cause sediment detachment and small events subsequently remove these sediments from near and in the channel. The RF method was applied to a daily dataset of sediment yield from the catchment (N=2451 days), and two subsets of the whole dataset: small events (N=2319) and large events (N=132). For sediment yield prediction of small events, variables related to large preceding events were the most important. The model for large events underperformed and, therefore, we could not draw any immediate conclusions whether small events influence the
Karloff, Howard
1991-01-01
To this reviewer’s knowledge, this is the first book accessible to the upper division undergraduate or beginning graduate student that surveys linear programming from the Simplex Method…via the Ellipsoid algorithm to Karmarkar’s algorithm. Moreover, its point of view is algorithmic and thus it provides both a history and a case history of work in complexity theory. The presentation is admirable; Karloff's style is informal (even humorous at times) without sacrificing anything necessary for understanding. Diagrams (including horizontal brackets that group terms) aid in providing clarity. The end-of-chapter notes are helpful...Recommended highly for acquisition, since it is not only a textbook, but can also be used for independent reading and study. —Choice Reviews The reader will be well served by reading the monograph from cover to cover. The author succeeds in providing a concise, readable, understandable introduction to modern linear programming. —Mathematics of Computing This is a textbook intend...
Khim, B. K.; Shim, J.; Yoon, H. I.; Kang, Y. C.; Jang, Y. H.
2007-06-01
Particulate suspended material was recovered over a 23-month period using two sediment traps deployed in shallow water (˜30 m deep) off the King Sejong Station located in Marian Cove of King George Island, West Antarctica. Variability in seasonal flux and geochemical characteristics of the sediment particles highlights seasonal patterns of sedimentation of both lithogenic (terrigenous) and biogenic particles in the coastal glaciomarine environment. All components including total mass flux, lithogenic particle flux and biogenic particle flux show distinct seasonal variation, with high recovery rates during the summer and low rates under winter fast ice. The major contributor to total mass flux is the lithogenic component, comprising from 88% during the summer months (about 21 g m -2 d -1) up to 97% during the winter season (about 2 g m -2 d -1). The lithogenic particle flux depends mainly on the amount of snow-melt (snow accumulation) delivered into the coastal region as well as on the resuspension of sedimentary materials. These fine-grained lithogenic particles are silt-to-clay sized, composed mostly of clay minerals weathered on King George Island. Biogenic particle flux is also seasonal. Winter flux is ˜0.2 g m -2 d -1, whereas the summer contribution increases more than tenfold, up to 2.6 g m -2 d -1. Different biogenic flux between the two summers indicates inter-annual variability to the spring-summer phytoplankton bloom. The maximum of lithogenic particle flux occurs over a short period of time, and follows the peak of biogenic particle flux, which lasts longer. The seasonal warming and sea-ice retreat result in change in seawater nutrient status and subsequent ice-edge phytoplankton production. Meanwhile, the meltwater input to Marian Cove from the coastal drainage in January to February plays a major role in transporting lithogenic particles into the shallow water environment, although the tidal currents may be the main agents of resuspension in this
McColl, Samuel T.; Fuller, Ian C.; Anderson, Brian; Tate, Rosie
2017-04-01
Climate and glacier fluctuations influence sediment supply to glacier forelands, which in turn influences down-valley hazards to infrastructure and tourism within glacier forelands. At Fox Glacier, one of New Zealand's most iconic and popular glaciers, rapid retreat has initiated a range of hillslope and valley floor responses, that present a cascade of hazards and changes that need to be carefully managed. Fox Glacier has retreated many kilometres historically, with 2.6 km of retreat since the mid-20th century, and a phase of rapid retreat of 50-340 m per year since 2009. To study the system response to past and ongoing glacial retreat at the Fox valley, morphological changes are being observed using time-lapse photography and the annual collection of high-resolution digital elevation models (DEMs) and orthophoto mosaics. The DEMs are being produced using Structure from Motion photogrammetry from UAV/RPAS and helicopter platforms, and are being used, along with manual ground surveying, to produce ground surface change models (DoDs; DEMs of Difference) and sediment budgets for the valley. Results from time-lapse photography and DoDs show that glacial retreat has initiated destabilisation and (mostly chronic) mass movement of surficial glacial sediments on the valley slopes near the glacier terminus. Alluvial fans farther down valley are actively growing, reworking glacial and landslide sediments from tributary catchments. These paraglacial sediments being delivered to the proglacial river from the glacier terminus and alluvial fans are driving aggradation of the valley floor of decimetres to metres per year and maintaining a highly dynamic braid plain. Valley floor changes also include the melting of buried dead ice, which are causing localised subsidence at the carpark and one of the alluvial fans. The unstable slopes and active debris fans, aggrading and highly active river channel, ground subsidence, add to the spectacle but also the hazards of the Fox valley
Wu, Y. H.; Nakakita, E.
2017-12-01
Hillslope stability is highly related to stress equilibrium near the top surface of soil-mantled hillslopes. Stress field in a hillslope can also be significantly altered by variable groundwater motion under the rainfall influence as well as by different vegetation above and below the slope. The topographic irregularity, biological effects from vegetation and variable rainfall patterns couple with others to make the prediction of shallow landslide complicated and difficult. In an increasing tendency of extreme rainfall, the mountainous area in Japan has suffered more and more shallow landslides. To better assess shallow landslide hazards, we would like to develop a new mechanically-based method to estimate the fully three-dimensional stress field in hillslopes. The surface soil-layer of hillslope is modelled as a poroelastic medium, and the tree surcharge on the slope surface is considered as a boundary input of stress forcing. The modelling of groundwater motion is involved to alter effective stress state in the soil layer, and the tree root-reinforcement estimated by allometric equations is taken into account for influencing the soil strength. The Mohr-Coulomb failure theory is then used for locating possible yielding surfaces, or says for identifying failure zones. This model is implemented by using the finite element method. Finally, we performed a case study of the real event of massive shallow landslides occurred in Hiroshima in August, 2014. The result shows good agreement with the field condition.
Reduction of Linear Programming to Linear Approximation
Vaserstein, Leonid N.
2006-01-01
It is well known that every Chebyshev linear approximation problem can be reduced to a linear program. In this paper we show that conversely every linear program can be reduced to a Chebyshev linear approximation problem.
Salcher, Bernhard; Baumann, Sebastian; Kober, Florian; Robl, Jörg; Heiniger, Lukas
2016-04-01
The analysis of the slope-area relationship in bedrock streams is a common way for discriminating the channel from the hillslope domain and associated landscape processes. Spatial variations of these domains are important indicators of landscape change. In fluvial catchments, this relationship is a function of contributing drainage area, channel slope and the threshold drainage area for fluvial erosion. The resulting pattern is related to climate, tectonic and underlying bedrock. These factors may become secondary in catchments affected by glacial erosion, as it is the case in many mid- to high-latitude mountain belts. The perturbation (i.e. the destruction) of an initial steady state fluvial bedrock morphology (where uplift is balanced by surface lowering rates) will tend to become successively larger if the repeated action of glacial processes exceeds the potential of fluvial readjustment during deglaciated periods. Topographic change is associated with a decrease and fragmentation of the channel network and an extension of the hillslope domain. In case of glacially conditioned catchments discrimination of the two domains remains problematic and a discrimination inconsistent. A definition is therefore highly needed considering that (i) a spatial shift in the domains affect the process and rate of erosion and (ii) topographic classifications of alpine catchments often base on channel and hillslope parameters (i.e.channel or hillslope relief). Here we propose a novel numerical approach to topographically define channel heads from digital topography in glacially conditioned mountain range catchments in order to discriminate the channel from the hillslope domain. We analyzed the topography of the southern European Central Alps, a region which (i) has been glaciated multiple times during the Quaternary, shows (ii) little lithological variations, is (iii) home of very low erodible rocks and is (iv) known as a region were tectonic processes have largely ceased. The
Kim, H.; Rempe, D. M.; Bishop, J. K.; Dietrich, W.; Fung, I.; Wood, T. J.
2012-12-01
The spatial and temporal pattern of groundwater chemistry in the seasonally perched groundwater systems that develop in the weathered bedrock zone under hillslopes have rarely been documented, yet chemical evolution of water here dictates the runoff chemistry to streams in many places. Here we exploit an intensively instrumented hillslope to document water well chemistry at three wells and adjacent stream. We have been sampling groundwater at daily frequency since October 2008 on a forested hillslope, "Rivendell", at the Angelo Coast Range Reserve located at the headwaters of the Eel River, California. The site is typical of California's coastal Mediterranean climate. The groundwater samples have been collected from a depth near the boundary between the weathered and fresh bedrock at three locations along the hillslope: Well 1 (bottom of hillslope), Well 3 (mid-slope), and Well 10 (near the ridge). Bulk rainwater and throughfall samples were collected at a meadow across the hillslope and at the middle of the slope, respectively, as well. Near the ridge (Well 10), during the first significant rainstorms of 2009 (133mm/42.5hours) and 2010 (220mm/42hours), when the water table changed only 0.32m and 0.66m, respectively, the concentration of Ca, Mg, and Na started to increase rapidly compared to the dry season (e.g. 2-6 μM vs 0.02-0.2μM [Mg]/day). However, during these same storms, K concentration sharply increased to 50-60 μM and decreased to 20-30μM, synchronizing with the water table responses. Throughfalls of these storms had at least 10 fold lower Ca, Mg, and Na concentrations than the well water while they had 10 fold higher K compared to the pre-event groundwater values. When the total seasonal cumulative rainfall exceeds 600 mm, the Well 10 solute concentration was diluted nearly 3 fold (e.g. [Mg] 0.3 mM vs. 0.1 mM) and the water table was raised significantly (2-6 meters). Throughout the rainy season, Well10 retained its diluted chemistry signature and on
Campforts, Benjamin; Vanacker, Veerle; Vanderborght, Jan; Baken, Stijn; Smolders, Erik; Govers, Gerard
2016-04-01
Meteoric 10Be allows for the quantification of vertical and lateral soil fluxes over long time scales (103-105 yr). However, the mobility of meteoric 10Be in the soil system makes a translation of meteoric 10Be inventories into erosion and deposition rates complex. Here, we present a spatially explicit 2D model simulating the behaviour of meteoric 10Be on a hillslope. The model consists of two parts. The first component deals with advective and diffusive mobility of meteoric 10Be within the soil profile, and the second component describes lateral soil and meteoric 10Be fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering as well as downslope fluxes of soil due to creep, water and tillage erosion. Synthetic model simulations show that meteoric 10Be inventories can be related to erosion and deposition across a wide range of geomorphological and pedological settings. Our results also show that meteoric 10Be can be used as a tracer to detect human impact on soil fluxes for soils with a high affinity for meteoric 10Be. However, the quantification of vertical mobility is essential for a correct interpretation of the observed variations in meteoric 10Be profiles and inventories. Application of the Be2D model to natural conditions using data sets from the Southern Piedmont (Bacon et al., 2012) and Appalachian Mountains (Jungers et al., 2009; West et al., 2013) allows to reliably constrain parameter values. Good agreement between simulated and observed meteoric 10Be concentrations and inventories is obtained with realistic parameter values. Furthermore, our results provide detailed insights into the processes redistributing meteoric 10Be at the soil-hillslope scale.
Schmengler, A. C.; Vlek, P. L. G.
2012-04-01
Modelling soil erosion requires a holistic understanding of the sediment dynamics in a complex environment. As most erosion models are scale-dependent and their parameterization is spatially limited, their application often requires special care, particularly in data-scarce environments. This study presents a hierarchical approach to overcome the limitations of a single model by using various quantitative methods and soil erosion models to cope with the issues of scale. At hillslope scale, the physically-based Water Erosion Prediction Project (WEPP)-model is used to simulate soil loss and deposition processes. Model simulations of soil loss vary between 5 to 50 t ha-1 yr-1 dependent on the spatial location on the hillslope and have only limited correspondence with the results of the 137Cs technique. These differences in absolute soil loss values could be either due to internal shortcomings of each approach or to external scale-related uncertainties. Pedo-geomorphological soil investigations along a catena confirm that estimations by the 137Cs technique are more appropriate in reflecting both the spatial extent and magnitude of soil erosion at hillslope scale. In order to account for sediment dynamics at a larger scale, the spatially-distributed WaTEM/SEDEM model is used to simulate soil erosion at catchment scale and to predict sediment delivery rates into a small water reservoir. Predicted sediment yield rates are compared with results gained from a bathymetric survey and sediment core analysis. Results show that specific sediment rates of 0.6 t ha-1 yr-1 by the model are in close agreement with observed sediment yield calculated from stratigraphical changes and downcore variations in 137Cs concentrations. Sediment erosion rates averaged over the entire catchment of 1 to 2 t ha-1 yr-1 are significantly lower than results obtained at hillslope scale confirming an inverse correlation between the magnitude of erosion rates and the spatial scale of the model. The
Kuhn, T. J.; Forrester, H.; Abney, R.; DeLong, S.; Roche, J. W.; Asefaw Berhe, A.
2016-12-01
The 2013 Rim Fire burned 1036 km2 in the Sierra Nevada, including 312 km2 within Yosemite National Park, and generated concern about post-fire effects in the Tuolumne River watershed. We evaluated hillslope erosion and water quality during the winter storm seasons of 2013-2015, in two small watersheds (3.0 and 3.6 km2) in Yosemite located within the rain-snow transition zone. Within a month of fire containment, we installed equipment to monitor streamflow, rainfall, turbidity, and total suspended solids during storms. On moderate and high severity burn areas (based on initial dNBR data), we established 21 plots (100-150 m2) to trap all sediment (≥ silt size) eroded from moderate to steep (11°-26°) slopes. Soil temperature sensors were installed at 14 plots to measure the presence of snow cover. Lastly, we conducted seven terrestrial lidar surveys to measure vegetation recovery and topographic change. In the three study years, precipitation intensity events were generally low and lacked more typical higher intensity storms (I-30 in mm: Min = 1.5; Max = 34.0; Median = 6.1). Preliminary results suggest that despite revegetation, a lack of intense storms during the 1st and 2nd years following the fire produced less suspended solids in streams than the 3rd year. Hillslope erosion in plots was controlled by burn severity, with moderate severity plots having significantly more transport of coarse material (>2mm, mainly litterfall) and high severity plots having significantly more fine material (geologic parent material; a topic of current analyses. The dominant surface processes revealed by lidar were sheetflow and minor rill formation in the plots, and rilling and gully erosion on slopes near the plots. Analyses of sediment produced from snow storms, or those with pre-existing snow cover, indicate sediment export is dampened by these conditions, and allow for partitioning of within-channel and hillslope sediment sources. Overall, initial analyses suggest that
Tanwiwat Jaikuna
2017-02-01
Full Text Available Purpose: To develop an in-house software program that is able to calculate and generate the biological dose distribution and biological dose volume histogram by physical dose conversion using the linear-quadratic-linear (LQL model. Material and methods : The Isobio software was developed using MATLAB version 2014b to calculate and generate the biological dose distribution and biological dose volume histograms. The physical dose from each voxel in treatment planning was extracted through Computational Environment for Radiotherapy Research (CERR, and the accuracy was verified by the differentiation between the dose volume histogram from CERR and the treatment planning system. An equivalent dose in 2 Gy fraction (EQD2 was calculated using biological effective dose (BED based on the LQL model. The software calculation and the manual calculation were compared for EQD2 verification with pair t-test statistical analysis using IBM SPSS Statistics version 22 (64-bit. Results: Two and three-dimensional biological dose distribution and biological dose volume histogram were displayed correctly by the Isobio software. Different physical doses were found between CERR and treatment planning system (TPS in Oncentra, with 3.33% in high-risk clinical target volume (HR-CTV determined by D90%, 0.56% in the bladder, 1.74% in the rectum when determined by D2cc, and less than 1% in Pinnacle. The difference in the EQD2 between the software calculation and the manual calculation was not significantly different with 0.00% at p-values 0.820, 0.095, and 0.593 for external beam radiation therapy (EBRT and 0.240, 0.320, and 0.849 for brachytherapy (BT in HR-CTV, bladder, and rectum, respectively. Conclusions : The Isobio software is a feasible tool to generate the biological dose distribution and biological dose volume histogram for treatment plan evaluation in both EBRT and BT.
Nezlobin, David; Pariente, Sarah; Lavee, Hanoch; Sachs, Eyal
2017-04-01
Source-sink systems are very common in hydrology; in particular, some land cover types often generate runoff (e.g. embedded rocks, bare soil) , while other obstruct it (e.g. vegetation, cracked soil). Surface runoff coefficients of patchy slopes/plots covered by runoff generating and obstructing covers (e.g., bare soil and vegetation) depend critically on the percentage cover (i.e. sources/sinks abundance) and decrease strongly with observation scale. The classic mathematical percolation theory provides a powerful apparatus for describing the runoff connectivity on patchy hillslopes, but it ignores strong effect of the overland flow directionality. To overcome this and other difficulties, modified percolation theory approaches can be considered, such as straight percolation (for the planar slopes), quasi-straight percolation and models with limited obstruction. These approaches may explain both the observed critical dependence of runoff coefficients on percentage cover and their scale decrease in systems with strong flow directionality (e.g. planar slopes). The contributing area increases sharply when the runoff generating percentage cover approaches the straight percolation threshold. This explains the strong increase of the surface runoff and erosion for relatively low values (normally less than 35%) of the obstructing cover (e.g., vegetation). Combinatorial models of urns with restricted occupancy can be applied for the analytic evaluation of meaningful straight percolation quantities, such as NOGA's (Non-Obstructed Generating Area) expected value and straight percolation probability. It is shown that the nature of the cover-related runoff scale decrease is combinatorial - the probability for the generated runoff to avoid obstruction in unit area decreases with scale for the non-trivial percentage cover values. The magnitude of the scale effect is found to be a skewed non-monotonous function of the percentage cover. It is shown that the cover-related scale
Can earthquake fissures predispose hillslopes to landslides? - Evidence from Central and East Asia
Sidle, Roy C.; Gomi, Takashi; Rajapbaev, Muslim; Chyngozhoev, Nurstan
2017-04-01
Factors affecting earthquake-initiated landslides include earthquake magnitude, focal depth, and seismic wave propagation and attenuation. In contrast to rainfall-initiated landslides, earthquake-induced landslides often occur on convex slopes and near ridgelines. Here we present evidence from Fergana Basin, Kyrgyzstan and Kumamoto, Japan on how fissures developed during earthquakes may promote subsequent initiation of rainfall-triggered landslides. More than 1800 recent major landslides in hilly terrain and soft sediments of the Fergana Basin have been largely attributed to accumulation of heavy rainfall and snowmelt. While no large earthquakes have occurred in the Fergana Basin, smaller earthquakes have generated fissures near ridgelines and on convex slopes. The connection of fissures, developed years or decades before slope failure, with preferential transport of rainwater and runoff into the soil has not been previously investigated. Fissures have been observed to expand with time, particularly during subsequent minor earthquakes, further promoting preferential infiltration. Because the soil mantle does not have large contrasts in permeability that would define a slip plane for landslides, it appears that the position and depth of these fissures may control the location and depth of failures. Zones in the soil where surficial inputs of water are preferentially transported, augment natural subsurface accumulation of antecedent rainfall. Many landslides in the eastern Fergana Basin occur after several months of accumulated precipitation and groundwater has been observed emerging on critical hillside locations (near ridgelines and on convex slopes) prior to slope failure. During the 2016 Kumamoto Earthquake (M 7.3), many landslides were triggered in forest and grassland hillslopes near Mount Aso. All of these earthquakes were shallow (focal depths about 10 km), causing high shaking intensity and ground rupturing. Because soils were relatively dry during these
Young, K. S.; Beganskas, S.; Fisher, A. T.
2017-12-01
We use a hydrologic model to analyze hillslope runoff under a range of climate and land use conditions in the San Lorenzo River Basin (SLRB), central coastal California, including contemporary land use and incremental deforestation. The SLRB is a heavily forested watershed with chronically overdrafted aquifers; in some areas, groundwater levels have been lowered by >50 m in recent decades. Managed aquifer recharge (MAR) can help mitigate declines in groundwater storage, routing excess surface flows to locations where they can infiltrate. We are especially interested in opportunities for collection of stormwater runoff, particularly where development and other changes in landuse have increased hill slope runoff. To assess hillslope runoff at the subwatershed scale (10-100 ha; 25-250 ac), we apply the Precipitation Runoff Modeling System (PRMS) to a high-resolution, digital elevation model and populate the simulation with area- and density-weighted vegetation and soil parameters calculated from high resolution input data. We also develop and apply a catalog of dry, normal, and wet climate scenarios from the historic record (1981-2014). In addition, we simulate conditions ranging from 0 to 100 percent of redwoods harvested (representing the mid-1800s to 1930s logging era) using a historical land use data set to alter soil and vegetation conditions. Results under contemporary land use suggest there are ample opportunities to establish MAR projects during all climate scenarios; hill slope runoff generation is spatially variable and on average exceeds 23,000 ac-ft/yr (3.2 in/yr) during the driest climate scenario. Preliminary results from the deforestation scenarios show notable increases in hillslope runoff with progressive redwood harvesting. Relative to pre-logging conditions, between 1.1 in (dry climates) and 1.5 in (wet climates) more runoff is generated under contemporary conditions, with most of the runoff increase occurring in urban areas. These modeling methods
Jack Lewis; Jim Baldwin
1997-01-01
The State of California has embarked upon a Long-Term Monitoring Program whose primary goal is to assess the effectiveness of the Forest Practice Rules and Review Process in protecting the beneficial uses of waters from the impacts of timber operations on private timberlands. The Board of Forestry's Monitoring Study Group concluded that hillslope monitoring should...
Distribution of rock fragments and their effects on hillslope soil erosion in purple soil, China
Wang, Xiaoyan
2017-04-01
influence of rock fragment cover on purple soil slope erosion process were carried on, under different conditions with two kind of rock fragment positions (resting on soil surface and embedded into top soil layer), varied rock fragment coverage (Rc, 0% 40%), two kind of soils with textural porosity or structural porosity, and three kind of rainfall intensities (I, 1 mm/min, 1.5 mm/min and 2 mm/min). Simulated rainfall experiments in situ plots in the field, combined with simulated rainfall experiments in soil pans indoor, were used. The main conclusions of this dissertation are as following: 1. The spatial distribution characteristics of rock fragments in purple soil slope and its effects on the soil physical properties were clarified basically. 2. The mechanism of influence of rock fragments within top soil layer on soil erosion processes was understood and a threshold of rock fragment content on the infiltration was figured out. 3. The relationships between surface rock fragment cover and hillslope soil erosion in purple soil under different conditions with varied rock fragment positions, soil structures and rainfall intensities were obtained and the soil and water conservation function of surface rock fragment cover on reducing soil loss was affirmed.
B. Zhang
2011-10-01
Full Text Available Subsurface lateral flow from agricultural hillslopes is often overlooked compared with overland flow and tile drain flow, partly due to the difficulties in monitoring and quantifying. The objectives of this study were to examine how subsurface lateral flow generated through soil pedons from cropped hillslopes and to quantify its contribution to nitrate loading in the streams through an agricultural catchment in the subtropical region of China. Profiles of soil water potential along hillslopes and stream hydro-chemographs in a trenched stream below a cropped hillslope and at the catchment outlet were simultaneously recorded during two rainstorm events. The dynamics of soil water potential showed positive matrix soil water potential over impermeable soil layer at 0.6 to 1.50 m depths during and after the storms, indicating soil water saturation and drainage processes along the hillslopes irrespective of land uses. The hydro-chemographs in the streams, one trenched below a cropped hillslope and one at the catchment outlet, showed that the concentrations of particulate nitrogen and phosphorus corresponded well to stream flow during the storm, while the nitrate concentration increased on the recession limbs of the hydrographs after the end of the storm. All the synchronous data revealed that nitrate was delivered from the cropped hillslope through subsurface lateral flow to the streams during and after the end of the rainstorms. A chemical mixing model based on electricity conductivity (EC and H^{+} concentration was successfully established, particularly for the trenched stream. The results showed that the subsurface lateral flow accounted for 29% to 45% of total stream flow in the trenched stream, responsible for 86% of total NO_{3}^{−}-N loss (or 26% of total N loss, and for 5.7% to 7.3% of total stream flow at the catchment outlet, responsible for about 69% of total NO_{3}^{−}-N loss (or 28% of total N
Linear Algebra and Smarandache Linear Algebra
Vasantha, Kandasamy
2003-01-01
The present book, on Smarandache linear algebra, not only studies the Smarandache analogues of linear algebra and its applications, it also aims to bridge the need for new research topics pertaining to linear algebra, purely in the algebraic sense. We have introduced Smarandache semilinear algebra, Smarandache bilinear algebra and Smarandache anti-linear algebra and their fuzzy equivalents. Moreover, in this book, we have brought out the study of linear algebra and vector spaces over finite p...
Campo, Julian; Cammeraat, Erik; Gimeno-García, Eugenia; Andreu, Vicente
2016-04-01
The Intergovernmental Panel on Climate Change indicated a higher degree of confidence that meteorological conditions associated to climate change will be propitious to increasing extreme events manifested, among others, in bigger and more frequent wildfires (IPCC, 2014). Wildfires contribute to shaping the landscape, and also the geomorphological and hydrological processes that operate on soil are affected (Bento-Gonçalves et al., 2012). Whereas, it is well documented that wildfires produce significant changes on erosion processes, the associated fate of soil organic carbon (SOC) has received less attention. This research assesses this gap by studying the loss, redistribution, and stabilization of SOC in a Mediterranean forest hill-slope burned the 28-08-2014, with high severity fire, at the Natural Park of Sierra de Espadán, Spain (39°50'45.11"N, 0°22'20.52"W). To this end, soil was sampled (19-9-2014) in the foot's slope (depositional), middle part (transport) and top (eroding) at two depths (test>146 drops). Significant differences (ANOVA, pBS) and soil depths (topsoil>subsoil). However, no significant differences were observed among eroding (58.8+20.8 gC kg-1), transport (67.3+34.4 gC kg-1), and depositional zones (62.0+31.3 gC kg-1), which is not in agreement with other SOC redistribution studies (Wang et al., 2014). Significant differences (Kruskal-Wallis, pBS) but not between soil depths or hill-slope positions. In the first post-fire erosive rains occurred in the area (29-11-14), closest pluviometer (Sot de Ferrer: 4.5 km) registered a total daily rain up to 64.2 l m-2. In this event a total of 12.7 kg of sediment were collected (contributing area ≈0.25 ha), with a content of 252.6 gC kg-1 the total SOC transported or stored in the depositional zone can reach up to 3.2 kg. In the second erosive event (23-3-15: 103.2 l m-2), total sediment in the fences was 143.6 kg, with content of 112.2 gC kg-1, made a total SOC eroded of up to 16.1 kg. It is
Kim, H.; Bishop, J. K.
2013-12-01
Groundwater flowing through weathered bedrock dictates the runoff chemistry to streams in many catchments yet; its chemical evolution has been rarely documented. In particular, observations of Fe and Mn dynamics in groundwater are extremely challenging due to their high reactivity. To preserve the sample integrity for these elements we have developed a new sampling scheme that is applicable to autosamplers; a gravitational filtration system (GFS). GFS is capable of filtering samples by gravity within 30 minutes after the sampling. The GFS samples showed a good agreement with reference samples, which were collected following the standard sampling method for trace metals (i.e. immediate filtration and acidification). Since October 2011, GFS has been employed to monitor Fe and Mn in perched groundwater that moves through weathered argillite in an intensively instrumented hillslope (Rivendell), in the Angelo Coast Range Reserve. The study site is located at the headwaters of the Eel River, northern California, characterized by a typical coastal Californian Mediterranean climate. We collected groundwater samples at 3 wells along the hillslope (upslope (W10), mid-slope (W3) and near the creek (W1)) with 1-3 day intervals. Additionally, rainwater and throughfall samples were collected at a meadow near the hillslope and at the middle of the hillslope, respectively. The results from our observations indicate that Fe and Mn exhibit distinct spatial and temporal behavior under variable hydrologic conditions. The concentrations of Fe in throughfall vs. rainwater were similar (0.45μM vs. 0.49μM), but Mn in throughfall was 10-fold higher than that in rainwater (1.2 μM vs. 0.1 μM). In the early rainy season, W10's water table was deep (-18m) and Fe and Mn in W10 were 30-150 nM and 1-2 μM, respectively. As the rainy season proceeds, W10's water table rose by 4-6m, indicating the arrival of new water. At this time, Mn in W10 decreased to ~0.1 μM, synchronizing with the water
Beverly, D.; Speckman, H. N.; Ewers, B. E.
2017-12-01
Ecosystem-scale models often rely on root vulnerability or whole-plant conductance for simulating seasonal evapotranspiration declines via constraints of water uptake and vegetation mortality. Further, many of these ecosystem models rely on single, unvarying, hydraulic parameter estimates for modeling large areas. Ring-porous species have shown seasonal variability in root vulnerability (percent loss of conductivity; PLC) and whole-plant conductance (Kw) but simulations of coniferous forest typically rely on point measurements. This assumption for coniferous forest is not likely true because of seasonal variability caused by phenology and environmental stresses and the potential for cavitation fatigue is not considered. Moreover, many of these dynamics have only been considered for stems even though roots are often the most vulnerable segments of the pathway for conifers. We hypothesized that seasonally dynamic whole-plant conductance along hillslope gradients in coniferous forests are regulated by cavitation fatigue within the roots resulting in seasonal increases in vulnerability. To test the hypothesis, a subalpine mixed forest (3000 m.a.s.l) and montane forest (2550 m.a.s.l.) were monitored between 2015-2017 to quantify PLC and Kw along the hillslope gradients of 300 m and 50 m, respectively. Forest plots were instrumented with 35 Granier-type sapflow sensors. Seasonal sampling campaigns occurred to quantify PLC through centrifuge techniques and Kw through Darcy's law approximations with pre-dawn and diurnal leaf water potentials. Downslope roots exhibit a 33% decrease in maximal conductivity corresponding to the approximately 50% decrease in whole-plant conductance suggesting seasonal soil dry-down limitations within the downslope stands. Upslope stands had no to little change in root vulnerability or decrease in whole-plant conductance as soil water limitations occur immediately following snowmelt, thus limiting hydraulic conductance throughout the growing
Spatial variability of steady-state infiltration into a two-layer soil system on burned hillslopes
Kinner, D.A.; Moody, J.A.
2010-01-01
Rainfall-runoff simulations were conducted to estimate the characteristics of the steady-state infiltration rate into 1-m2 north- and south-facing hillslope plots burned by a wildfire in October 2003. Soil profiles in the plots consisted of a two-layer system composed of an ash on top of sandy mineral soil. Multiple rainfall rates (18.4-51.2 mm h-1) were used during 14 short-duration (30 min) and 2 long-duration simulations (2-4 h). Steady state was reached in 7-26 min. Observed spatially-averaged steady-state infiltration rates ranged from 18.2 to 23.8 mm h-1 for north-facing and from 17.9 to 36.0 mm h-1 for south-facing plots. Three different theoretical spatial distribution models of steady-state infiltration rate were fit to the measurements of rainfall rate and steady-state discharge to provided estimates of the spatial average (19.2-22.2 mm h-1) and the coefficient of variation (0.11-0.40) of infiltration rates, overland flow contributing area (74-90% of the plot area), and infiltration threshold (19.0-26 mm h-1). Tensiometer measurements indicated a downward moving pressure wave and suggest that infiltration-excess overland flow is the runoff process on these burned hillslope with a two-layer system. Moreover, the results indicate that the ash layer is wettable, may restrict water flow into the underlying layer, and increase the infiltration threshold; whereas, the underlying mineral soil, though coarser, limits the infiltration rate. These results of the spatial variability of steady-state infiltration can be used to develop physically-based rainfall-runoff models for burned areas with a two-layer soil system. ?? 2010 Elsevier B.V.
Lee, S. S.; Rempe, D. M.; Holbrook, W. S.; Schmidt, L.; Hahm, W. J.; Dietrich, W. E.
2017-12-01
Except for boreholes and road cut, landslide, and quarry exposures, the subsurface structure of the critical zone (CZ) of weathered bedrock is relatively invisible and unmapped, yet this structure controls the short and long term fluxes of water and solutes. Non-invasive geophysical methods such as seismic refraction are widely applied to image the structure of the CZ at the hillslope scale. However, interpretations of such data are often limited due to heterogeneity and anisotropy contributed from fracturing, moisture content, and mineralogy on the seismic signal. We develop a quantitative framework for using seismic refraction tomography from intersecting geophysical surveys and hydrologic data obtained at the Eel River Critical Zone Observatory (ERCZO) in Northern California to help quantify the nature of subsurface structure across multiple hillslopes of varying topography in the area. To enhance our understanding of modeled velocity gradients and boundaries in relation to lithological properties, we compare refraction tomography results with borehole logs of nuclear magnetic resonance (NMR), gamma and neutron density, standard penetration testing, and observation drilling logs. We also incorporate laboratory scale rock characterization including mineralogical and elemental analyses as well as porosity and density measurements made via pycnometry, helium and mercury porosimetry, and laboratory scale NMR. We evaluate the sensitivity of seismically inferred saprolite-weathered bedrock and weathered-unweathered bedrock boundaries to various velocity and inversion parameters in relation with other macro scale processes such as gravitational and tectonic forces in influencing weathered bedrock velocities. Together, our sensitivity analyses and multi-method data comparison provide insight into the interpretation of seismic refraction tomography for the quantification of CZ structure and hydrologic dynamics.
Scaini, Anna; Hissler, Christophe; Fenicia, Fabrizio; Juilleret, Jérôme; Iffly, Jean François; Pfister, Laurent; Beven, Keith
2018-03-01
Subsurface flow is often recognized as a dominant runoff generation process. However, observing subsurface properties, and understanding how they control flow pathways, remains challenging. This paper investigates how surface slope and bedrock cleavage control subsurface flow pathways in a slate bedrock headwater catchment in Luxembourg, characterised by a double-peak streamflow response. We use a range of experimental techniques, including field observations of soil and bedrock characteristics, and a sprinkling experiment at a site located 40 m upslope from the stream channel. The sprinkling experiment uses Br- as a tracer, which is measured at a well downslope from the plot and at various locations along the stream, together with well and stream hydrometric responses. The sprinkling experiment is used to estimate velocities and celerities, which in turn are used to infer flow pathways. Our results indicate that the single or first peak of double-peak events is rainfall-driven (controlled by rainfall) while the second peak is storage-driven (controlled by storage). The comparison between velocity and celerity estimates suggests a fast flowpath component connecting the hillslope to the stream, but velocity information was too scarce to fully support such a hypothesis. In addition, different estimates of celerities suggest a seasonal influence of both rainfall intensity rate and residual water storage on the celerity responses at the hillslope scale. At the catchment outlet, the estimated of the total mass of Br- recovered in the stream was about 2.5% of the application. Further downstream, the estimate mass of Br- was about 4.0% of the application. This demonstrates that flowpaths do not appear to align with the slope gradient. In contrast, they appear to follow the strike of the bedrock cleavage. Our results have expanded our understanding of the importance of the subsurface, in particular the underlying bedrock systems, and the importance of cleavage orientation
Wang, X.; Yoo, K.; Wackett, A. A.; Gutknecht, J.; Amundson, R.; Heimsath, A. M.
2017-12-01
Climate and topography have been widely recognized as important factors regulating soil organic carbon (SOC) dynamics but their interactive effects on SOC storage and its pools remain poorly constrained. Here we aimed to evaluate SOC storages and carbon-mineral interactions along two hillslope transects with moderately different climates (MAP: 549 mm vs. 816 mm) in Southeastern Australia. We sampled soil along the convex (eroding)-to-convergent (depositional) continuum at each hillslope transect and conducted size and density fractionation of these samples. In responses to the difference in climate factor, SOC inventories of eroding soils were twice as large at the wetter site compared with the drier site but showed little difference between two sites in depositional soils. These trends in SOC inventories were primarily controlled by SOC concentrations and secondarily by soil thicknesses. Similar patterns were observed for mineral associated organic carbon (MOC), and the abundances of MOC were controlled by the two independently operating processes affecting MOC concentration and fine-heavy fraction minerals. The contents and species of secondary clay and iron oxide minerals, abundances of particulate organic carbon, and bioturbation affected MOC concentrations. In contrast, the abundances of fine-heavy fraction minerals were impacted by erosion mechanisms that uniquely responded to regional- and micro- climate conditions. Consequently, topographic influences on SOC inventories and carbon-mineral interactions were more strongly pronounced in the drier climate where vegetation and erosion mechanisms were sensitive to microclimate. Our results highlight the significance of understanding topography and erosional processes in capturing climatic effects on soil carbon dynamics.
Linearly constrained minimax optimization
Madsen, Kaj; Schjær-Jacobsen, Hans
1978-01-01
We present an algorithm for nonlinear minimax optimization subject to linear equality and inequality constraints which requires first order partial derivatives. The algorithm is based on successive linear approximations to the functions defining the problem. The resulting linear subproblems...
Ding Hu; Lang Yunchao; Liu Congqiang
2011-01-01
Land use and land cover changes can cause variations in terrestrial energy, water balance and availability of nutrients. To understand the role of vegetation in regulating the hydrochemistry of karst hillslopes, overland flow and soil seepage water from two hillslopes covered with and without vegetation were studied in the Huanjiang Observation and Research Station for Karst Ecosystems, Guangxi, SW China. Dissolved major ions, as well as isotopic compositions of dissolved inorganic C (DIC) were examined. Water from the vegetated control slope had higher solute concentrations (except NO 3 - ) and lower δ 13 C values than water from the disturbed slope. The dynamics of K + and NO 3 - in soil water sampled in time-sequence from the control slope was different from the disturbed slope. Specifically, K + and NO 3 - concentrations of the control slope decreased gradually over time, while K + and NO 3 - concentrations of the disturbed slope increased, and other ionic concentrations increased in both of the slopes.
Koci, J.; Jarihani, B.; Sidle, R. C.; Wilkinson, S. N.; Bartley, R.
2017-12-01
Structure from Motion with Multi-View Stereo (SfM-MVS) photogrammetry provides a cost-effective method of rapidly acquiring high resolution (sub-meter) topographic data, but is rarely used in hydrogeomorphic investigations of gully erosion. This study integrates high resolution topographic and land cover data derived from an unmanned aerial vehicle (UAV) and ground-based SfM-MVS photogrammetry, with rainfall and gully discharge data, to elucidate hydrogeomorphic processes driving hillslope gully erosion. The study is located within a small (13 km2) dry-tropical savanna catchment within the Burdekin River Basin, northeast Australia, which is a major contributor sediments and nutrients to the Great Barrier Reef World Heritage Area. A pre-wet season UAV survey covered an entire hillslope gully system (0.715 km2), and is used to derive topography, ground cover and hydrological flow pathways in the gully contributing area. Ground-based surveys of a single active gully (650 m2) within the broader hillslope are compared between pre- and post-wet season conditions to quantify gully geomorphic change. Rainfall, recorded near to the head of the gully, is related to gully discharge during sporadic storm events. The study provides valuable insights into the relationships among hydrological flow pathways, ground cover, rainfall and runoff, and spatial patterns of gully morphologic change. We demonstrate how UAV and ground-based SfM-MVS photogrammetry can be used to improve hydrogeomorphic process understanding and aid in the modelling and management of hillslope gully systems.
Li, Changjia; Pan, Chengzhong
2018-03-01
The effects of vegetation cover on overland flow and erosion processes on hillslopes vary with vegetation type and spatial distribution and the different vegetation components, including the above- and below-ground biomass. However, few attempts have been made to quantify how these factors affect erosion processes. Field experimental plots (5 m × 2 m) with a slope of approximately 25° were constructed and simulated rainfall (60 mm hr-1) (Rainfall) and simulated rainfall combined with upslope overland flow (20 L min-1) (Rainfall + Flow) were applied. Three grass species were planted, specifically Astragalus adsurgens (A. adsurgens), Medicago sativa (M. sativa) and Cosmos bipinnatus (C. bipinnatus). To isolate and quantify the relative contributions of the above-ground grass parts (stems, litter cover and leaves) and the roots to reducing surface runoff and erosion, each of the three grass species was subjected to three treatments: intact grass control (IG), no litter or leaves (only the grass stems and roots were reserved) (NLL), and only roots remaining (OR). The results showed that planting grass significantly reduced overland flow rate and velocity and sediment yield, and the mean reductions were 21.8%, 29.1% and 67.1%, respectively. M. sativa performed the best in controlling water and soil losses due to its thick canopy and dense, fine roots. Grasses reduced soil erosion mainly during the early stage of overland flow generation. The above-ground grass parts primarily contributed to reducing overland flow rate and velocity, with mean relative contributions of 64% and 86%, respectively. The roots played a predominant role in reducing soil erosion, with mean contribution of 84%. Due to the impact of upslope inflow, overland flow rate and velocity and sediment yield increased under the Rainfall + Flow conditions. The results suggest that grass species on downslope parts of semi-arid hillslopes performed better in reducing water and soil losses. This study is
Tian, P.; Xu, X.; Pan, C.; Hsu, K. L.; Yang, T.
2016-12-01
Few attempts have been made to investigate the quantitative effects of rainfall on overland flow driven erosion processes and flow hydrodynamics on steep hillslopes under field conditions. Field experiments were performed in flows for six inflow rates (q: 6-36 Lmin-1m-1) with and without rainfall (60 mm h-1) on a steep slope (26°) to investigate: (1) the quantitative effects of rainfall on runoff and sediment yield processes, and flow hydrodynamics; (2) the effect of interaction between rainfall and overland flow on soil loss. Results showed that the rainfall increased runoff coefficients and the fluctuation of temporal variations in runoff. The rainfall significantly increased soil loss (10.6-68.0%), but this increment declined as q increased. When the interrill erosion dominated (q=6 Lmin-1m-1), the increment in the rill erosion was 1.5 times that in the interrill erosion, and the effect of the interaction on soil loss was negative. When the rill erosion dominated (q=6-36 Lmin-1m-1), the increment in the interrill erosion was 1.7-8.8 times that in the rill erosion, and the effect of the interaction on soil loss became positive. The rainfall was conducive to the development of rills especially for low inflow rates. The rainfall always decreased interrill flow velocity, decreased rill flow velocity (q=6-24 Lmin-1m-1), and enhanced the spatial uniformity of the velocity distribution. Under rainfall disturbance, flow depth, Reynolds number (Re) and resistance were increased but Froude number was reduced, and lower Re was needed to transform a laminar flow to turbulent flow. The rainfall significantly increased flow shear stress (τ) and stream power (φ), with the most sensitive parameters to sediment yield being τ (R2=0.994) and φ (R2=0.993), respectively, for non-rainfall and rainfall conditions. Compared to non-rainfall conditions, there was a reduction in the critical hydrodynamic parameters of mean flow velocity, τ, and φ by the rainfall. These findings
Foundations of linear and generalized linear models
Agresti, Alan
2015-01-01
A valuable overview of the most important ideas and results in statistical analysis Written by a highly-experienced author, Foundations of Linear and Generalized Linear Models is a clear and comprehensive guide to the key concepts and results of linear statistical models. The book presents a broad, in-depth overview of the most commonly used statistical models by discussing the theory underlying the models, R software applications, and examples with crafted models to elucidate key ideas and promote practical model building. The book begins by illustrating the fundamentals of linear models,
Gellis, Allen C.; Emmett, William W.; Leopold, Luna Bergere
2005-01-01
Detailed documentation of geomorphic changes in the landscape of more than a few years is rarely possible. Channel cross sections, channel profiles, sediment deposition behind dams, and hillslope-erosion plots, originally benchmarked within several watersheds outside Santa Fe, New Mexico, in the 1950’s and 1960’s, for a 1966 report that documented processes and rates of arid-region sediment production and deposition, were resurveyed in the mid-1990’s. Many of the original study sites were relocated and surveyed in the mid-1990’s to determine subsequent channel and hillslope changes and to determine whether trends of channel and hillslope aggradation and degradation that were evident in the 1950’s and 1960’s have continued. In general, the net change in channel geometry has been small over the last 30–40 years. The average change in cross-sectional area of 32 resurveyed cross sections was erosion of 0.27 square meter, which equates to a 4-percent increase in cross-sectional area. The average net change in thalweg elevation for 51 resurveyed cross sections was degradation of 0.04 meter. Unpublished data (1964–68) from the scour chains showed that 371 chains had an average scour of 0.14 ± 0.14 meter and that 372 chains showed an average fill of 0.13 + 0.11 meter. Scour, found in the original study (1958–64) to be proportional to the square root of discharge, was confirmed with the addition of unpublished data (1964–68). The observed channel changes have no consistent trend, compared either to results observed in the original 1966 study or to distance from the watershed divide. The conclusion drawn in the original study was that most channels were aggrading; the resurvey showed that aggradation did not continue.An increase in housing and population in the Arroyo de los Frijoles watershed since the 1950’s has led to more roads. Channel degradation is most noticeable at road crossings. The greatest degradation of the main channel Arroyo de los
Lin, Hsueh-Chun; Hong, Yao-Ming; Kan, Yao-Chiang
2012-01-01
The groundwater level represents a critical factor to evaluate hillside landslides. A monitoring system upon the real-time prediction platform with online analytical functions is important to forecast the groundwater level due to instantaneously monitored data when the heavy precipitation raises the groundwater level under the hillslope and causes instability. This study is to design the backend of an environmental monitoring system with efficient algorithms for machine learning and knowledge bank for the groundwater level fluctuation prediction. A Web-based platform upon the model-view controller-based architecture is established with technology of Web services and engineering data warehouse to support online analytical process and feedback risk assessment parameters for real-time prediction. The proposed system incorporates models of hydrological computation, machine learning, Web services, and online prediction to satisfy varieties of risk assessment requirements and approaches of hazard prevention. The rainfall data monitored from the potential landslide area at Lu-Shan, Nantou and Li-Shan, Taichung, in Taiwan, are applied to examine the system design.
Kim, M.; Harman, C. J.; Troch, P. A. A.
2017-12-01
Hillslopes have been extensively explored as a natural fundamental unit for spatially-integrated hydrologic models. Much of this attention has focused on their use in predicting the quantity of discharge, but hillslope-based models can potentially be used to predict the composition of discharge (in terms of age and chemistry) if they can be parameterized terms of measurable physical properties. Here we present advances in the use of rank StorAge Selection (rSAS) functions to parameterize transport through hillslopes. These functions provide a mapping between the distribution of water ages in storage and in outfluxes in terms of a probability distribution over storage. It has previously been shown that rSAS functions are related to the relative partitioning and arrangement of flow pathways (and variabilities in that arrangement), while separating out the effect of changes in the overall rate of fluxes in and out. This suggests that rSAS functions should have a connection to the internal organization of flow paths in a hillslope.Using a combination of numerical modeling and theoretical analysis we examined: first, the controls of physical properties on internal spatial organization of age (time since entry), life expectancy (time to exit), and the emergent transit time distribution and rSAS functions; second, the possible parameterization of the rSAS function using the physical properties. The numerical modeling results showed the clear dependence of the rSAS function forms on the physical properties and relations between the internal organization and the rSAS functions. For the different rates of the exponential saturated hydraulic conductivity decline with depth the spatial organization of life expectancy varied dramatically and determined the rSAS function forms, while the organizaiton of the age showed less qualitative differences. Analytical solutions predicting this spatial organization and the resulting rSAS function were derived for simplified systems. These
Tuey, R. C.
1972-01-01
Computer solutions of linear programming problems are outlined. Information covers vector spaces, convex sets, and matrix algebra elements for solving simultaneous linear equations. Dual problems, reduced cost analysis, ranges, and error analysis are illustrated.
Peterson, David; Stofleth, Jerome H.; Saul, Venner W.
2017-07-11
Linear shaped charges are described herein. In a general embodiment, the linear shaped charge has an explosive with an elongated arrowhead-shaped profile. The linear shaped charge also has and an elongated v-shaped liner that is inset into a recess of the explosive. Another linear shaped charge includes an explosive that is shaped as a star-shaped prism. Liners are inset into crevices of the explosive, where the explosive acts as a tamper.
Classifying Linear Canonical Relations
Lorand, Jonathan
2015-01-01
In this Master's thesis, we consider the problem of classifying, up to conjugation by linear symplectomorphisms, linear canonical relations (lagrangian correspondences) from a finite-dimensional symplectic vector space to itself. We give an elementary introduction to the theory of linear canonical relations and present partial results toward the classification problem. This exposition should be accessible to undergraduate students with a basic familiarity with linear algebra.
Falco, N.; Wainwright, H. M.; Dafflon, B.; Leger, E.; Peterson, J.; Steltzer, H.; Wilmer, C.; Williams, K. H.; Hubbard, S. S.
2017-12-01
Mountainous watershed systems are characterized by extreme heterogeneity in hydrological and pedological properties that influence biotic activities, plant communities and their dynamics. To gain predictive understanding of how ecosystem and watershed system evolve under climate change, it is critical to capture such heterogeneity and to quantify the effect of key environmental variables such as topography, and soil properties. In this study, we exploit advanced geophysical and remote sensing techniques - coupled with machine learning - to better characterize and quantify the interactions between plant communities' distribution and subsurface properties. First, we have developed a remote sensing data fusion framework based on the random forest (RF) classification algorithm to estimate the spatial distribution of plant communities. The framework allows the integration of both plant spectral and structural information, which are derived from multispectral satellite images and airborne LiDAR data. We then use the RF method to evaluate the estimated plant community map, exploiting the subsurface properties (such as bedrock depth, soil moisture and other properties) and geomorphological parameters (such as slope, curvature) as predictors. Datasets include high-resolution geophysical data (electrical resistivity tomography) and LiDAR digital elevation maps. We demonstrate our approach on a mountain hillslope and meadow within the East River watershed in Colorado, which is considered to be a representative headwater catchment in the Upper Colorado Basin. The obtained results show the existence of co-evolution between above and below-ground processes; in particular, dominant shrub communities in wet and flat areas. We show that successful integration of remote sensing data with geophysical measurements allows identifying and quantifying the key environmental controls on plant communities' distribution, and provides insights into their potential changes in the future
Wang, Dichen; Fan, Haoming; Fan, Xiangguo
2017-09-17
Gully erosion is an important environmental problem worldwide and the main process by which water and soil losses occur in the Black Soil Region (BSR) of Northeast China. At the end of 2012, 295,663 gullies were present in this region. However, few studies have examined the gullies of the Black Soil Region as a whole. Studying the distribution of recent gullies can reveal the pattern of gully distribution and can help predict their spatial development according to the soil and water conservation regionalization of China. This study examines the recorded gullies in the BSR of Northeast China, which is included in the first census of water resources in China and in six sub-regions of the soil and water conservation regionalization of China. Specifically, digital elevation model (DEM) data are combined with data on gullies occurring on hillslopes with different slopes and aspects to study the distribution of these features. The results illustrate that gully density, developing gully density, and the proportion of cutting land initially increase with increasing slope up to some threshold value, then decrease as the slope increases further. The patterns of stable gullies are divided into unimodal and bimodal types. Three patterns of gully intensity are identified. The areas and lengths of gullies are larger on sunny slopes, but larger numbers of gullies are present on shaded slopes. In addition, more space is available for gully development in the Hulun Buir hilly and plain sub-region and the Changbai Mountain-Wanda Mountain sub-region than in the other sub-regions.
Rush, M.; Rajaram, H.; Anderson, R. S.; Anderson, S. P.
2017-12-01
The Intergovernmental Panel on Climate Change (2013) warns that high-elevation ecosystems are extremely vulnerable to climate change due to short growing seasons, thin soils, sparse vegetation, melting glaciers, and thawing permafrost. Many permafrost-free regions experience seasonally frozen ground. The spatial distribution of frozen soil exerts a strong control on subsurface flow and transport processes by reducing soil permeability and impeding infiltration. Accordingly, evolution of the extent and duration of frozen ground may alter streamflow seasonality, groundwater flow paths, and subsurface storage, presenting a need for coupled thermal-hydrologic models to project hydrologic responses to climate warming in high-elevation regions. To be useful as predictive tools, such models should incorporate the heterogeneity of solar insolation, vegetation, and snowpack dynamics. We present a coupled thermal-hydrologic modeling study against the backdrop of field observations from Gordon Gulch, a seasonally snow-covered montane catchment in the Colorado Front Range in the Boulder Creek Critical Zone Observatory. The field site features two instrumented hillslopes with opposing aspects: the snowpack on the north-facing slope persists throughout much of the winter season, while the snowpack on the south-facing slope is highly ephemeral. We implemented a surface energy balance and snowpack accumulation and ablation model that is coupled to the subsurface flow and transport code PFLOTRAN-ICE to predict the hydrologic consequences of aspect-controlled frozen soil formation during water years 2013-2016. Preliminary model results demonstrate the occurrence of seasonally-frozen ground on the north-facing slope that directs snowmelt to the stream by way of shallow subsurface flow paths. The absence of persistently frozen ground on the south-facing slope allows deeper infiltration of snowmelt recharge. The differences in subsurface flow paths also suggest strong aspect
Wacha, K.; Papanicolaou, T.; Hatfield, J.; Cambardella, C.; Abban, B. K.; Wilson, C. G.; Filley, T. R.; Hou, T.; Dold, C.
2017-12-01
The abundance and distribution of surface soil size fractions has been shown to be reflective of changes in management practices and landscape position. Soil size fractions exist in both un-aggregated and aggregated forms that differ in textural and biological composition, which can impact soil hydrology and aggregation processes. Soils with higher stocks of soil organic matter (SOM) promote higher biological activity, infiltration, and soil structure due to stronger, more resilient aggregates. Within ag-systems, intensive cultivation and steep gradients can negatively impact the formation/stability of aggregates and amplify erosion processes, which redistributes material along downslope flowpathways to varying degrees, based on the amount of available surface cover during a rainfall event. The innate variability in SOM composition found amongst the size fractions combined with these highly active flowpathways, produces a symphony of interactive biogeochemical and hydrologic processes, which promote spatial landscape heterogeneity. Due to this intricacy, accurately assessing changes in SOM stocks within high energy ag-systems is extremely challenging, and could greatly impact soil carbon budgets at the hillslope and greater spatial scales. To address this, in part, we utilize a systematic approach that isolates the role of management in building aggregate resilience to hydrologic forcing. Soil samples were collected from farm fields with varying slopes (1-20%) and management conditions, and then isolated into seven aggregate size fractions. Each aggregate fraction was tested for resilience to raindrop impact with corresponding SOM composition and biological activity. Rainfall simulations were conducted on plots under representative management and gradient to capture the dynamicity of the size fractions being transported during an applied rainfall event. Results found that small macroaggregate fractions were most indicative of changes in management, and erosion
Green, Timothy R.; Erskine, Robert H.
2011-12-01
Dynamics of profile soil water vary with terrain, soil, and plant characteristics. The objectives addressed here are to quantify dynamic soil water content over a range of slope positions, infer soil profile water fluxes, and identify locations most likely influenced by multidimensional flow. The instrumented 56 ha watershed lies mostly within a dryland (rainfed) wheat field in semiarid eastern Colorado. Dielectric capacitance sensors were used to infer hourly soil water content for approximately 8 years (minus missing data) at 18 hillslope positions and four or more depths. Based on previous research and a new algorithm, sensor measurements (resonant frequency) were rescaled to estimate soil permittivity, then corrected for temperature effects on bulk electrical conductivity before inferring soil water content. Using a mass-conservation method, we analyzed multitemporal changes in soil water content at each sensor to infer the dynamics of water flux at different depths and landscape positions. At summit positions vertical processes appear to control profile soil water dynamics. At downslope positions infrequent overland flow and unsaturated subsurface lateral flow appear to influence soil water dynamics. Crop water use accounts for much of the variability in soil water between transects that are either cropped or fallow in alternating years, while soil hydraulic properties and near-surface hydrology affect soil water variability across landscape positions within each management zone. The observed spatiotemporal patterns exhibit the joint effects of short-term hydrology and long-term soil development. Quantitative methods of analyzing soil water patterns in space and time improve our understanding of dominant soil hydrological processes and provide alternative measures of model performance.
Yu-bin Zhang
2010-01-01
Full Text Available Water pollution from agricultural fields is a global problem and cause of eutrophication of surface waters. A laboratory study was designed to evaluate the effects of near-surface hydraulic gradients on NO3–N and NH4–N losses in surface runoff from soil boxes at 27% slope undersimulated rainfall of a loess soil hillslope. Experimental treatments included two near-surface hydraulic gradients (free drainage, FD; saturation, SA, three fertilizer application rates (control, no fertilizer input; low, 120 kg N ha-1; high, 240 kg N ha-1, and simulated rainfall of 100 mm h-1 was applied for 70 min. The results showed that saturated near-surface soil moisture had dramatic effects on NO3–N and NH4–N losses and water quality. Under the low fertilizer treatment, average NO3–N concentrations in runoff water of SA averaged 2.2 times greater than that of FD, 1.6 times greater for NH4–N. Under the high fertilizer treatment, NO3–N concentrations in runoff water from SA averaged 5.7 times greater than that of FD, 4.3 times greater for NH4–N. Nitrogen loss formed with NO3–N is dominant during the event, but not NH4–N. Under the SA condition, the total loss of NO3–N from low fertilizer treatment was 34.2 to 42.3% of applied nitrogen, while under the FD treatment that was 3.9 to 6.9%. However, the total loss of NH4–N was less than 1% of applied nitrogen. These results showed that saturated condition could make significant contribution to water quality problems.
Lawson, C. L.; Krogh, F. T.; Gold, S. S.; Kincaid, D. R.; Sullivan, J.; Williams, E.; Hanson, R. J.; Haskell, K.; Dongarra, J.; Moler, C. B.
1982-01-01
The Basic Linear Algebra Subprograms (BLAS) library is a collection of 38 FORTRAN-callable routines for performing basic operations of numerical linear algebra. BLAS library is portable and efficient source of basic operations for designers of programs involving linear algebriac computations. BLAS library is supplied in portable FORTRAN and Assembler code versions for IBM 370, UNIVAC 1100 and CDC 6000 series computers.
Dias da Cunha, Kenya Moore; Henderson, Helenes; Thomson, Bruce M; Hecht, Adam A
2014-06-01
in the majority of the water samples, indicating more than one source of contamination could contribute to the sampled sources. The effective doses due to ingestion of the minimum uranium concentrations in water samples exceed the average dose considering inhalation and ingestion of regular diet for other populations around the world (1 μSv/year). The maximum doses due to ingestion of (238)U or (234)U were above the international limit for effective dose for members of the public (1 mSv/year), except for inhabitants of two chapters. The highest effective dose was estimated for inhabitants of Cove, and it was almost 20 times the international limit for members of the public. These results indicate that ingestion of water from some of the sampled sources poses health risks.
Beganskas, S.; Young, K. S.; Fisher, A. T.; Lozano, S.; Harmon, R. E.; Teo, E. K.
2017-12-01
We are applying a regional hydrology model, Precipitation-Runoff Modeling System (PRMS), to evaluate locations for groundwater replenishment with hillslope runoff in the Pajaro Valley Groundwater Basin (PVGB), central coastal California. Stormwater managed aquifer recharge (MAR) projects collect hillslope runoff before it reaches a stream and infiltrate it into underlying aquifers, improving groundwater supply. The PVGB is a developed agricultural basin where groundwater provides >85% of water for irrigation and municipal needs; stormwater-MAR projects are being considered to address chronic overdraft and saltwater intrusion. We are applying PRMS to assess on a subwatershed scale (10-100 ha; 25-250 acres) where adequate runoff is generated to supply stormwater-MAR in coincidence with suitable conditions for infiltration and recharge. Data from active stormwater-MAR projects in the PVGB provide ground truth for model results. We are also examining how basinwide hydrology responds to changing land use and climate, and the potential implications for future water management. To prepare extensive input files for PRMS models, we developed ArcGIS and Python tools to delineate a topographic model grid and incorporate high-resolution soil, vegetation, and other physical data into each grid region; we also developed tools to analyze and visualize model output. Using historic climate records, we generated dry, normal, and wet climate scenarios, defined as having approximately 25th, 50th, and 75th percentile annual rainfall, respectively. We also generated multiple land use scenarios by replacing developed areas with native vegetation. Preliminary results indicate that many parts of the PVGB generate significant runoff and have suitable infiltration/recharge conditions. Reducing basinwide overdraft by 10% would require collecting less than 5% of total hillslope runoff, even during the dry scenario; this demonstrates that stormwater-MAR could be an effective water management
Quinn, C.; Dixon, J. L.; Wilcox, A. C.
2017-12-01
In steep, mountainous landscapes, interactions between soil, rock, and biotic factors combine to form complex feedbacks. Here, we explore the dynamic interplay between soil and vegetation and its influence on hillslope sediment storage and movement in the Bitterroot Range of Montana's Rocky Mountains. We focus on a set of analogous forested and non-forested hillslopes along Lost Horse Creek, where avalanche paths determine vegetative density without significant impact on other topographic variables. LiDAR, high-resolution aerial photography, and field mapping are used to determine the local and landscape variables that influence soil cover and sediment storage. We find high-resolution surface roughness is a useful remote proxy to identify bedrock and boulder outcrops, particularly beneath canopy cover. Based on this analysis and field mapping, the spatial extent of soil cover does not vary significantly between forested and non-forested regions, though soils are generally thicker under forest cover. We additionally measure fallout radiogenic nuclides (FRNs; Cs-137 and Pb-210) in soils across 40 sites to provide insight into short-term soil erosion and movement. Preliminary results show high spatial variability in FRN activities of mineral soils in both systems, which may reflect either spatially variable delivery or soil erosion. Additionally, FRN activity of surface litter and duff at the forest floor is three to four times higher than mineral soils in both the forested and non-forested sites, suggesting that FRNs may provide a novel tracer of carbon storage and export. Our results show that the coupled use of isotopic tracers and high resolution spatial data reveal quantitative insights into landscape scale hillslope soil dynamics.
Anderson, A. E.; Weiler, M.
2005-12-01
Preferential flow is a complex process that influences water flow and solute transport in soils at different scales. Many studies have advanced our understanding about the physical structures of preferential pathways and their effects on water flow and solute transport at the column and plot scale. However, we still know very little about how preferential flow features connect over large distances and how they influence water flow and solute transport at the hillslope and catchment scale. Working in a forested watershed on northeast Vancouver Island in British Columbia, Canada, we conducted several artificial tracer experiments under natural and steady state flow conditions to investigate how water and solutes move through a hillslope section above a road cutbank. After these ``black-box'' tracer experiments we applied a blue food dye and excavated the hillslope to visualize the stained flow pathways. Under natural conditions two of the largest preferential features transmitted water at rates up to 30 liters/min. When a NaCl tracer was applied 12 m upslope of the road cutbank one soil pipe transmitted 97% of the recovered tracer during two large storms. When tracer was applied 30 m upslope of the road a more diffused response was observed. For the steady-state conditions we pumped water into trenches excavated at 12 m and 30 m above the road and then applied NaCl during constant outflow. Pumping water into the 12 m trench produced flow from only two preferential features, but a response in all preferential features was observed when water was pumped into the 30 m trench. The detailed excavations showed that the largest preferential feature was connected to the lower trench by large soil pipes at the interface of the organic and mineral soil horizons that were connected by flow through the organic soil. Other cross sections between 12 and 30 m upslope revealed concentrated flow through coarse mineral soil, diffused flow through mineral and organic soil, flow along
Leclere, S.; Sklar, L. S.; Genetti, J. R.
2014-12-01
The size distribution of sediments produced on hillslopes and supplied to channels depends on the geomorphic processes that weather, detach and transport rock fragments down slopes. Little in the way of theory or data is available to predict patterns in hillslope size distributions at the catchment scale from topographic and geologic maps. Here we use aerial imagery and a variety of remote sensing techniques to map and categorize geomorphic landscape units (GLUs) by inferred sediment production process regime, across the steep mountain catchment of Inyo Creek, eastern Sierra Nevada, California. We also use field measurements of particle size and local geomorphic attributes to test and refine GLU determinations. Across the 2 km of relief in this catchment, landcover varies from bare bedrock cliffs at higher elevations to vegetated, regolith-covered convex slopes at lower elevations. Hillslope gradient could provide a simple index of sediment production process, from rock spallation and landsliding at highest slopes, to tree-throw and other disturbance-driven soil production processes at lowest slopes. However, many other attributes are needed for a more robust predictive model, including elevation, curvature, aspect, drainage area, and color. We combine tools from ArcGIS, ERDAS Imagine and Envi with groundtruthing field work to find an optimal combination of attributes for defining sediment production GLUs. Key challenges include distinguishing: weathered from freshly eroded bedrock, boulders from intact bedrock, and landslide deposits from talus slopes. We take advantage of emerging technologies that provide new ways of conducting fieldwork and comparing field data to mapping solutions. In particular, cellphone GPS is approaching the accuracy of dedicated GPS systems and the ability to geo-reference photos simplifies field notes and increases accuracy of later map creation. However, the predictive power of the GLU mapping approach is limited by inherent uncertainty
Traper, Sandra; Pöppl, Ronald; Rascher, Eric; Sass, Oliver
2016-04-01
In recent times different types of natural disasters like debris flow events have attracted increasing attention worldwide, since they can cause great damage and loss of infrastructure or even lives is not unusual when it comes to such an event. The engagement with debris flows is especially important in mountainous areas like Austria, since Alpine regions have proved to be particularly prone to the often harmful consequences of such events because of increasing settlement of previously uninhabited regions. Due to those frequently damaging effects of debris flows, research on this kind of natural disaster often focuses on mitigation and recovery measures after an event and on how to restore the initial situation. However, a view on the situation of an area, where severe debris flows recently occurred and are well documented, before the actual event can aid in discovering important preparatory factors that contribute to initiating debris flows and hillslope-channel connectivity in the first place. Valuable insights into the functioning and preconditions of debris flows and their potential connectivity to the main channel can be gained. The study focuses on two geologically different areas in the Austrian Alps, which are both prone to debris flows and have experienced rather severe events recently. Based on data from debris flow events in two regions in Styria (Austria), the Kleinsölk and the Johnsbach valleys, the aim of the study is to identify factors which influence the development of debris flows and the potential of such debris flows to reach the main channel potentially clogging up the river (hillslope-channel connectivity). The degree of hillslope-channel coupling was verified in extensive TLS and ALS surveys, resulting in DEMs of different resolution and spatial extension. Those factors are obtained, analyzed and evaluated with DEM-based GIS- and statistical analyses. These include factors that are attributed to catchment topography, such as slope angle
Non linear system become linear system
Petre Bucur
2007-01-01
Full Text Available The present paper refers to the theory and the practice of the systems regarding non-linear systems and their applications. We aimed the integration of these systems to elaborate their response as well as to highlight some outstanding features.
Linear motor coil assembly and linear motor
2009-01-01
An ironless linear motor (5) comprising a magnet track (53) and a coil assembly (50) operating in cooperation with said magnet track (53) and having a plurality of concentrated multi-turn coils (31 a-f, 41 a-d, 51 a-k), wherein the end windings (31E) of the coils (31 a-f, 41 a-e) are substantially
Wiedemann, H.
1981-11-01
Since no linear colliders have been built yet it is difficult to know at what energy the linear cost scaling of linear colliders drops below the quadratic scaling of storage rings. There is, however, no doubt that a linear collider facility for a center of mass energy above say 500 GeV is significantly cheaper than an equivalent storage ring. In order to make the linear collider principle feasible at very high energies a number of problems have to be solved. There are two kinds of problems: one which is related to the feasibility of the principle and the other kind of problems is associated with minimizing the cost of constructing and operating such a facility. This lecture series describes the problems and possible solutions. Since the real test of a principle requires the construction of a prototype I will in the last chapter describe the SLC project at the Stanford Linear Accelerator Center.
Blyth, T S
2002-01-01
Basic Linear Algebra is a text for first year students leading from concrete examples to abstract theorems, via tutorial-type exercises. More exercises (of the kind a student may expect in examination papers) are grouped at the end of each section. The book covers the most important basics of any first course on linear algebra, explaining the algebra of matrices with applications to analytic geometry, systems of linear equations, difference equations and complex numbers. Linear equations are treated via Hermite normal forms which provides a successful and concrete explanation of the notion of linear independence. Another important highlight is the connection between linear mappings and matrices leading to the change of basis theorem which opens the door to the notion of similarity. This new and revised edition features additional exercises and coverage of Cramer's rule (omitted from the first edition). However, it is the new, extra chapter on computer assistance that will be of particular interest to readers:...
Wiedemann, H.
1981-11-01
Since no linear colliders have been built yet it is difficult to know at what energy the linear cost scaling of linear colliders drops below the quadratic scaling of storage rings. There is, however, no doubt that a linear collider facility for a center of mass energy above say 500 GeV is significantly cheaper than an equivalent storage ring. In order to make the linear collider principle feasible at very high energies a number of problems have to be solved. There are two kinds of problems: one which is related to the feasibility of the principle and the other kind of problems is associated with minimizing the cost of constructing and operating such a facility. This lecture series describes the problems and possible solutions. Since the real test of a principle requires the construction of a prototype I will in the last chapter describe the SLC project at the Stanford Linear Accelerator Center
Matrices and linear transformations
Cullen, Charles G
1990-01-01
""Comprehensive . . . an excellent introduction to the subject."" - Electronic Engineer's Design Magazine.This introductory textbook, aimed at sophomore- and junior-level undergraduates in mathematics, engineering, and the physical sciences, offers a smooth, in-depth treatment of linear algebra and matrix theory. The major objects of study are matrices over an arbitrary field. Contents include Matrices and Linear Systems; Vector Spaces; Determinants; Linear Transformations; Similarity: Part I and Part II; Polynomials and Polynomial Matrices; Matrix Analysis; and Numerical Methods. The first
Efficient Non Linear Loudspeakers
Petersen, Bo R.; Agerkvist, Finn T.
2006-01-01
Loudspeakers have traditionally been designed to be as linear as possible. However, as techniques for compensating non linearities are emerging, it becomes possible to use other design criteria. This paper present and examines a new idea for improving the efficiency of loudspeakers at high levels...... by changing the voice coil layout. This deliberate non-linear design has the benefit that a smaller amplifier can be used, which has the benefit of reducing system cost as well as reducing power consumption....
Faraway, Julian J
2014-01-01
A Hands-On Way to Learning Data AnalysisPart of the core of statistics, linear models are used to make predictions and explain the relationship between the response and the predictors. Understanding linear models is crucial to a broader competence in the practice of statistics. Linear Models with R, Second Edition explains how to use linear models in physical science, engineering, social science, and business applications. The book incorporates several improvements that reflect how the world of R has greatly expanded since the publication of the first edition.New to the Second EditionReorganiz
Carr, Joseph
1996-01-01
The linear IC market is large and growing, as is the demand for well trained technicians and engineers who understand how these devices work and how to apply them. Linear Integrated Circuits provides in-depth coverage of the devices and their operation, but not at the expense of practical applications in which linear devices figure prominently. This book is written for a wide readership from FE and first degree students, to hobbyists and professionals.Chapter 1 offers a general introduction that will provide students with the foundations of linear IC technology. From chapter 2 onwa
Fault tolerant linear actuator
Tesar, Delbert
2004-09-14
In varying embodiments, the fault tolerant linear actuator of the present invention is a new and improved linear actuator with fault tolerance and positional control that may incorporate velocity summing, force summing, or a combination of the two. In one embodiment, the invention offers a velocity summing arrangement with a differential gear between two prime movers driving a cage, which then drives a linear spindle screw transmission. Other embodiments feature two prime movers driving separate linear spindle screw transmissions, one internal and one external, in a totally concentric and compact integrated module.
Superconducting linear accelerator cryostat
Ben-Zvi, I.; Elkonin, B.V.; Sokolowski, J.S.
1984-01-01
A large vertical cryostat for a superconducting linear accelerator using quarter wave resonators has been developed. The essential technical details, operational experience and performance are described. (author)
Heinze, Thomas; Möhring, Simon; Budler, Jasmin; Weigand, Maximilian; Kemna, Andreas
2017-04-01
Rainfall-triggered landslides are a latent danger in almost any place of the world. Due to climate change heavy rainfalls might occur more often, increasing the risk of landslides. With pore pressure as mechanical trigger, knowledge of water content distribution in the ground is essential for hazard analysis during monitoring of potentially dangerous rainfall events. Geophysical methods like electrical resistivity tomography (ERT) can be utilized to determine the spatial distribution of water content using established soil physical relationships between bulk electrical resistivity and water content. However, often more dominant electrical contrasts due to lithological structures outplay these hydraulic signatures and blur the results in the inversion process. Additionally, the inversion of ERT data requires further constraints. In the standard Occam inversion method, a smoothness constraint is used, assuming that soil properties change softly in space. This applies in many scenarios, as for example during infiltration of water without a clear saturation front. Sharp lithological layers with strongly divergent hydrological parameters, as often found in landslide prone hillslopes, on the other hand, are typically badly resolved by standard ERT. We use a structurally constrained ERT inversion approach for improving water content estimation in landslide prone hills by including a-priori information about lithological layers. Here the standard smoothness constraint is reduced along layer boundaries identified using seismic data or other additional sources. This approach significantly improves water content estimations, because in landslide prone hills often a layer of rather high hydraulic conductivity is followed by a hydraulic barrier like clay-rich soil, causing higher pore pressures. One saturated layer and one almost drained layer typically result also in a sharp contrast in electrical resistivity, assuming that surface conductivity of the soil does not change in
Ding Hu; Lang Yunchao [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 46th Guanshui Road, Guiyang 550002 (China); Liu Congqiang, E-mail: liucongqiang@vip.skleg.cn [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 46th Guanshui Road, Guiyang 550002 (China)
2011-06-15
Land use and land cover changes can cause variations in terrestrial energy, water balance and availability of nutrients. To understand the role of vegetation in regulating the hydrochemistry of karst hillslopes, overland flow and soil seepage water from two hillslopes covered with and without vegetation were studied in the Huanjiang Observation and Research Station for Karst Ecosystems, Guangxi, SW China. Dissolved major ions, as well as isotopic compositions of dissolved inorganic C (DIC) were examined. Water from the vegetated control slope had higher solute concentrations (except NO{sub 3}{sup -}) and lower {delta}{sup 13}C values than water from the disturbed slope. The dynamics of K{sup +} and NO{sub 3}{sup -} in soil water sampled in time-sequence from the control slope was different from the disturbed slope. Specifically, K{sup +} and NO{sub 3}{sup -} concentrations of the control slope decreased gradually over time, while K{sup +} and NO{sub 3}{sup -} concentrations of the disturbed slope increased, and other ionic concentrations increased in both of the slopes.
Bangxiang Li
2017-01-01
Full Text Available In this paper, a series of numerical simulations are performed to analyze the in situ stress distribution characteristics of the rock mass near different slope angles hillslope surfaces, which are subjected to the vertical gravity stress and different horizontal lateral stresses and the influence which the in situ stress distribution characteristics of 45° hillslope to the integral stability of surrounding rock mass when an underground cavern is excavated considering three different horizontal distances from the underground cavern to the slope surface. It can be concluded from the numerical results that different slope angles and horizontal lateral stresses have a strong impact on the in situ stress distribution and the integral surrounding rock mass stability of the underground cavern when the horizontal distance from the underground cavern to the slope surface is approximately 100 m to 200 m. The relevant results would provide some important constructive suggestions to the engineering site selection and optimization of large-scale underground caverns in hydropower stations.
Martínez-Casasnovas, José A; Ramos, María Concepción; Espinal-Utgés, Sílvia
2010-04-01
The availability of heavy machinery and the vineyard restructuring and conversion plans of the European Union Common Agricultural Policy (Commission Regulation EC no. 1227/2000 of 31 May 2000) have encouraged the restructuring of many vineyards on hillslopes of Mediterranean Europe, through the creation of terraces to favor the mechanization of agricultural work. Terrace construction requires cutting and filling operations that create soil spatial variability, which affects soil properties and plant development. In the present paper, we study the effects of hillslope terracing on the spatial variability of the normalized difference vegetation index (NDVI) in fields of the Priorat region (NE Spain) during 2004, 2005, and 2006. This index was computed from high-resolution remote sensing data (Quickbird-2). Detailed digital terrain models before and after terrace construction were used to assess the earth movements. The results indicate that terracing by heavy machinery induced high variability on the NDVI values over the years, showing significant differences as effect of the cut and fill operations.
Kereszturi, Gábor; Németh, Károly
2016-08-01
Conical volcanic edifices that are made up from lapilli to block/bomb pyroclastic successions, such as scoria cones, are widespread in terrestrial and extraterrestrial settings. Eruptive processes responsible for establishing the final facies architecture of a scoria cone are not well linked to numerical simulations of their post-eruptive sediment transport. Using sedimentological, geomorphic and 2D fragment morphology data from a 15-ky-old scoria cone from the Cima Volcanic Field, California, this study provides field evidence of the various post-eruptive sediment transport and degradation processes of scoria cones located in arid to semi-arid environments. This study has revealed that pyroclast morphologies vary downslope due to syn-eruptive granular flows, along with post-eruptive modification by rolling, bouncing and sliding of individual particles down a slope, and overland flow processes. The variability of sediment transport rates on hillslopes are not directly controlled by local slope angle variability and the flank length but rather by grain size, and morphological characteristics of particles, such as shape irregularity of pyroclast fragments and block/lapilli ratio. Due to the abundance of hillslopes degrading in unvegetated regions, such as those found in the Southwestern USA, granulometric influences should be accounted for in the formulation of sediment transport laws for geomorphic modification of volcanic terrains over long geologic time.
Patten, B.C.
1983-04-01
Two issues concerning linearity or nonlinearity of natural systems are considered. Each is related to one of the two alternative defining properties of linear systems, superposition and decomposition. Superposition exists when a linear combination of inputs to a system results in the same linear combination of outputs that individually correspond to the original inputs. To demonstrate this property it is necessary that all initial states and inputs of the system which impinge on the output in question be included in the linear combination manipulation. As this is difficult or impossible to do with real systems of any complexity, nature appears nonlinear even though it may be linear. A linear system that displays nonlinear behavior for this reason is termed pseudononlinear. The decomposition property exists when the dynamic response of a system can be partitioned into an input-free portion due to state plus a state-free portion due to input. This is a characteristic of all linear systems, but not of nonlinear systems. Without the decomposition property, it is not possible to distinguish which portions of a system's behavior are due to innate characteristics (self) vs. outside conditions (environment), which is an important class of questions in biology and ecology. Some philosophical aspects of these findings are then considered. It is suggested that those ecologists who hold to the view that organisms and their environments are separate entities are in effect embracing a linear view of nature, even though their belief systems and mathematical models tend to be nonlinear. On the other hand, those who consider that organism-environment complex forms a single inseparable unit are implictly involved in non-linear thought, which may be in conflict with the linear modes and models that some of them use. The need to rectify these ambivalences on the part of both groups is indicated.
Linear colliders - prospects 1985
Rees, J.
1985-06-01
We discuss the scaling laws of linear colliders and their consequences for accelerator design. We then report on the SLAC Linear Collider project and comment on experience gained on that project and its application to future colliders. 9 refs., 2 figs
Richter, B.
1985-01-01
A report is given on the goals and progress of the SLAC Linear Collider. The author discusses the status of the machine and the detectors and give an overview of the physics which can be done at this new facility. He also gives some ideas on how (and why) large linear colliders of the future should be built
Rogner, H.H.
1989-01-01
The submitted sections on linear programming are extracted from 'Theorie und Technik der Planung' (1978) by W. Blaas and P. Henseler and reformulated for presentation at the Workshop. They consider a brief introduction to the theory of linear programming and to some essential aspects of the SIMPLEX solution algorithm for the purposes of economic planning processes. 1 fig
Rowe, C.H.; Wilton, M.S. de.
1979-01-01
An improved recirculating electron beam linear accelerator of the racetrack type is described. The system comprises a beam path of four straight legs with four Pretzel bending magnets at the end of each leg to direct the beam into the next leg of the beam path. At least one of the beam path legs includes a linear accelerator. (UK)
Semidefinite linear complementarity problems
Eckhardt, U.
1978-04-01
Semidefinite linear complementarity problems arise by discretization of variational inequalities describing e.g. elastic contact problems, free boundary value problems etc. In the present paper linear complementarity problems are introduced and the theory as well as the numerical treatment of them are described. In the special case of semidefinite linear complementarity problems a numerical method is presented which combines the advantages of elimination and iteration methods without suffering from their drawbacks. This new method has very attractive properties since it has a high degree of invariance with respect to the representation of the set of all feasible solutions of a linear complementarity problem by linear inequalities. By means of some practical applications the properties of the new method are demonstrated. (orig.) [de
Axler, Sheldon
2015-01-01
This best-selling textbook for a second course in linear algebra is aimed at undergrad math majors and graduate students. The novel approach taken here banishes determinants to the end of the book. The text focuses on the central goal of linear algebra: understanding the structure of linear operators on finite-dimensional vector spaces. The author has taken unusual care to motivate concepts and to simplify proofs. A variety of interesting exercises in each chapter helps students understand and manipulate the objects of linear algebra. The third edition contains major improvements and revisions throughout the book. More than 300 new exercises have been added since the previous edition. Many new examples have been added to illustrate the key ideas of linear algebra. New topics covered in the book include product spaces, quotient spaces, and dual spaces. Beautiful new formatting creates pages with an unusually pleasant appearance in both print and electronic versions. No prerequisites are assumed other than the ...
Handbook on linear motor application
1988-10-01
This book guides the application for Linear motor. It lists classification and speciality of Linear Motor, terms of linear-induction motor, principle of the Motor, types on one-side linear-induction motor, bilateral linear-induction motor, linear-DC Motor on basic of the motor, linear-DC Motor for moving-coil type, linear-DC motor for permanent-magnet moving type, linear-DC motor for electricity non-utility type, linear-pulse motor for variable motor, linear-pulse motor for permanent magneto type, linear-vibration actuator, linear-vibration actuator for moving-coil type, linear synchronous motor, linear electromagnetic motor, linear electromagnetic solenoid, technical organization and magnetic levitation and linear motor and sensor.
Linear ubiquitination in immunity.
Shimizu, Yutaka; Taraborrelli, Lucia; Walczak, Henning
2015-07-01
Linear ubiquitination is a post-translational protein modification recently discovered to be crucial for innate and adaptive immune signaling. The function of linear ubiquitin chains is regulated at multiple levels: generation, recognition, and removal. These chains are generated by the linear ubiquitin chain assembly complex (LUBAC), the only known ubiquitin E3 capable of forming the linear ubiquitin linkage de novo. LUBAC is not only relevant for activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs) in various signaling pathways, but importantly, it also regulates cell death downstream of immune receptors capable of inducing this response. Recognition of the linear ubiquitin linkage is specifically mediated by certain ubiquitin receptors, which is crucial for translation into the intended signaling outputs. LUBAC deficiency results in attenuated gene activation and increased cell death, causing pathologic conditions in both, mice, and humans. Removal of ubiquitin chains is mediated by deubiquitinases (DUBs). Two of them, OTULIN and CYLD, are constitutively associated with LUBAC. Here, we review the current knowledge on linear ubiquitination in immune signaling pathways and the biochemical mechanisms as to how linear polyubiquitin exerts its functions distinctly from those of other ubiquitin linkage types. © 2015 The Authors. Immunological Reviews Published by John Wiley & Sons Ltd.
Krivonos, S.O.; Sorin, A.S.
1994-06-01
We show that the Zamolodchikov's and Polyakov-Bershadsky nonlinear algebras W 3 and W (2) 3 can be embedded as subalgebras into some linear algebras with finite set of currents. Using these linear algebras we find new field realizations of W (2) 3 and W 3 which could be a starting point for constructing new versions of W-string theories. We also reveal a number of hidden relationships between W 3 and W (2) 3 . We conjecture that similar linear algebras can exist for other W-algebra as well. (author). 10 refs
Schneider, Hans
1989-01-01
Linear algebra is one of the central disciplines in mathematics. A student of pure mathematics must know linear algebra if he is to continue with modern algebra or functional analysis. Much of the mathematics now taught to engineers and physicists requires it.This well-known and highly regarded text makes the subject accessible to undergraduates with little mathematical experience. Written mainly for students in physics, engineering, economics, and other fields outside mathematics, the book gives the theory of matrices and applications to systems of linear equations, as well as many related t
Linearity in Process Languages
Nygaard, Mikkel; Winskel, Glynn
2002-01-01
The meaning and mathematical consequences of linearity (managing without a presumed ability to copy) are studied for a path-based model of processes which is also a model of affine-linear logic. This connection yields an affine-linear language for processes, automatically respecting open......-map bisimulation, in which a range of process operations can be expressed. An operational semantics is provided for the tensor fragment of the language. Different ways to make assemblies of processes lead to different choices of exponential, some of which respect bisimulation....
Amir-Moez, A R; Sneddon, I N
1962-01-01
Elements of Linear Space is a detailed treatment of the elements of linear spaces, including real spaces with no more than three dimensions and complex n-dimensional spaces. The geometry of conic sections and quadric surfaces is considered, along with algebraic structures, especially vector spaces and transformations. Problems drawn from various branches of geometry are given.Comprised of 12 chapters, this volume begins with an introduction to real Euclidean space, followed by a discussion on linear transformations and matrices. The addition and multiplication of transformations and matrices a
Weisberg, Sanford
2013-01-01
Praise for the Third Edition ""...this is an excellent book which could easily be used as a course text...""-International Statistical Institute The Fourth Edition of Applied Linear Regression provides a thorough update of the basic theory and methodology of linear regression modeling. Demonstrating the practical applications of linear regression analysis techniques, the Fourth Edition uses interesting, real-world exercises and examples. Stressing central concepts such as model building, understanding parameters, assessing fit and reliability, and drawing conclusions, the new edition illus
Non-linearities in Holocene floodplain sediment storage
Notebaert, Bastiaan; Nils, Broothaerts; Jean-François, Berger; Gert, Verstraeten
2013-04-01
Floodplain sediment storage is an important part of the sediment cascade model, buffering sediment delivery between hillslopes and oceans, which is hitherto not fully quantified in contrast to other global sediment budget components. Quantification and dating of floodplain sediment storage is data and financially demanding, limiting contemporary estimates for larger spatial units to simple linear extrapolations from a number of smaller catchments. In this paper we will present non-linearities in both space and time for floodplain sediment budgets in three different catchments. Holocene floodplain sediments of the Dijle catchment in the Belgian loess region, show a clear distinction between morphological stages: early Holocene peat accumulation, followed by mineral floodplain aggradation from the start of the agricultural period on. Contrary to previous assumptions, detailed dating of this morphological change at different shows an important non-linearity in geomorphologic changes of the floodplain, both between and within cross sections. A second example comes from the Pre-Alpine French Valdaine region, where non-linearities and complex system behavior exists between (temporal) patterns of soil erosion and floodplain sediment deposition. In this region Holocene floodplain deposition is characterized by different cut-and-fill phases. The quantification of these different phases shows a complicated image of increasing and decreasing floodplain sediment storage, which hampers the image of increasing sediment accumulation over time. Although fill stages may correspond with large quantities of deposited sediment and traditionally calculated sedimentation rates for such stages are high, they do not necessary correspond with a long-term net increase in floodplain deposition. A third example is based on the floodplain sediment storage in the Amblève catchment, located in the Belgian Ardennes uplands. Detailed floodplain sediment quantification for this catchments shows
Wetzel, C. E.; Martínez-Carreras, N.; Ector, L.; Hlubikova, D.; Frentress, J.; McDonnell, J. J.; Hoffmann, L.; Pfister, L.
2012-04-01
In recent years, there have been increasingly calls for new eco-hydrological approaches to answer questions on water source and connectivity in the landscape. Diatoms are one of the most common and diverse algal groups, and offer the potential for the identification of reproducible flow patterns and a link to underlying watershed behaviour. Our preliminary investigations on the potential for terrestrial diatoms to detect the onset/cessation of surface runoff suggested that diatoms can contribute to confirm or reject the existence of a surface runoff component in total runoff, thereby helping to constrain assumptions made on a potential surface runoff component in a conventional tracer based hydrograph separation. Our investigations currently focus on the Attert River basin (Luxembourg, Europe) and the HJ Andrews experimental forest (Oregon, USA). Here we show results from the schistose Weierbach experimental catchment (0.45 km2), located in the Attert River basin. Ordination analysis revealed a clear distinction between communities belonging to the river bed substrate and the riparian zone. Drift samples corresponding to stream water show a mixed composition of diatoms stemming from the river bed substrate and the riparian zone. Ongoing investigations focus on the composition of hillslope communities. In winter, long-lasting low intensity rainfall events generate a two-tailed hydrograph response of the Weierbach, consisting in an immediate reaction to precipitation, followed by a delayed and much more significant rise of the hydrograph. For these events, mixing diagrams (SiO2 & Absorbance) suggest a substantial contribution of the soil water component to total runoff, with groundwater and especially overland flow remaining insignificant. Terrestrial diatom abundance appeared to be very sensitive to incident precipitation (rising to +/- 15% of the total diatom population), suggesting a rapid connectivity between the soil surface and the stream. In summer, short and
Matherne, Anne Marie; Tillery, Anne C.; Douglas-Mankin, Kyle R.
2018-04-10
Sediment erosion and deposition in two sets of paired (treated and untreated) upland drainages in the Torreon Wash watershed, upper Rio Puerco Basin, New Mexico, were examined over a 3 1/2-year period from spring 2009 through fall 2012. The objective was to evaluate the effectiveness of shallow, loose-stone check dams, or “one-rock dams,” as a hillslope gully erosion stabilization and mitigation method, and its potential for retaining upland eroded soils and decreasing delivery of sediment to lower ephemeral stream channels. Two high-resolution topographic surveys, completed at the beginning and end of the study period, were used to assess the effects of the mitigation measures at paired-drainage sites in both Penistaja Arroyo and Papers Wash watersheds, and at six main-stem-channel cross-section clusters along Penistaja Arroyo and Torreon Wash in the Torreon Wash watershed.For both drainage pairs, the treated drainage had greater sediment aggradation near the channel than the untreated drainage. Erosion was the dominant geomorphic process in the untreated Penistaja Arroyo drainage, whereas aggradation was the dominant process in the other three drainages. For the Penistaja Arroyo paired drainages, the treated site showed a 51-percent increase in area aggraded and 67-percent increase in volume aggraded per area analyzed over the untreated site. Both Papers Wash drainages showed net aggradation, but with similar treatment effect, with the treated site showing a 29-percent increase in area aggraded and 60-percent increase in volume aggraded per area analyzed over the untreated site. In the untreated Penistaja Arroyo drainage, the calculated minimum erosion rate was 0.0055 inches per year (in/yr; 0.14 millimeters per year [mm/yr]), whereas the calculated aggradation rates for the three drainages for which aggradation was the dominant geomorphic process were 0.0063 in/yr (0.16 mm/yr) for the Penistaja Arroyo treated drainage, 0.012 in/yr (0.31 mm/yr) for the Papers
Callier, Frank M.; Desoer, Charles A.
1991-01-01
The aim of this book is to provide a systematic and rigorous access to the main topics of linear state-space system theory in both the continuous-time case and the discrete-time case; and the I/O description of linear systems. The main thrusts of the work are the analysis of system descriptions and derivations of their properties, LQ-optimal control, state feedback and state estimation, and MIMO unity-feedback systems.
Linnik, Vitaly; Nenko, Kristina; Sokolov, Alexander; Saveliev, Anatoly
2015-04-01
In the result of Chernobyl disaster on 26 April 1986 many regions of Ukraine, Belarus and Russia were contaminated by radionuclides. Vast areas of farmlands and woodlands were contaminated in Russia. The deposited radionuclides continue to cause concern about the possible contamination of food (in particular, mushrooms and berries). But the radioactive materials are also an ideal marker for understanding of hillslope processes in natural and seminatural landscapes. Model area chosen for the research (Opolje landscapes located in the central part of the Bryansk region) is characterized by relatively low levels of Cs-137 contamination. It just 4-33 times higher than global fallout which was equal 1,75 kBq/m2 in 1986 . According the results of air gamma survey (grid size: 100 m x100 m), which was done in 1993, it was explicitly to identify that the processes of Cs-137 lateral migration took place due to nearly fourfold increase of Cs-137 in the lower slope in comparison with the surface of the watershed during a seven-year period after Chernobyl accident. Erosion processes which define Cs-137 pattern in the lowest part of hillslope depend upon such parameters as slope, hillslope forms, vegetation, land use and the roads, which intersect a streamline. GIS-modeling of Cs-137 was carried out in SAGA software. The spatial modeling resolution was equal 100x100 m according the air-gamma data. SRTM data was resampled to a grid 100x100 m. Erosion rates were the highest on the slope of southern exposure. There the processes of lateral migration are more intensive and observed within the entire slope. The main contribution in receipt of Cs-137 to floodplain on the northern slopes comes only from the lower part of the slope and gullies and ravines network. We have used geo-information modeling techniques and some kind of interpolation and statistical models to predict or understand forming of Cs-137 spatial patterns and trends in soil erosion. To study the role of some
Alila, Y.; Schnorbus, M.
2005-12-01
The debate regarding peak flow responses to forest clearcutting and road building in the maritime regions of the Pacific Northwest has attracted much attention over the past several decades and its outcome is an important scientific and operational concern. Although there appears to be general consensus that small peak discharge events are increased following forest management activities, little conclusive evidence exists regarding the impact of forest management activities on large events. Statistical tests in traditional paired watershed studies have been used to accept or reject hypotheses regarding peak flow responses to clearcutting and roads but provided no insight into watershed processes and other factors leading to their outcome. Furthermore, statistical analyses of peak flow responses to forestry activities in traditional paired watershed studies are confounded by the many factors that may contribute to management effects on watershed hydrology as well as by issues such as shortness of streamflow records and climate variability. To this end, a new perspective is offered in the debate regarding peak flow responses to clearcutting and road building in the maritime regions of the Pacific Northwest by combining numerical modeling with high-quality hydro-meteorological data collected at the 10-km2 Carnation Creek on the west coast of Vancouver Island, British Columbia (BC). In this approach we explicitly account for changes in evapotranspiration loss, forest road construction and, in particular, introduce the concept of the competing influences of matrix versus preferential hillslope runoff. For scenarios involving road construction, forest clearcutting (52% cut rate) and roads and clearcutting combined, peak discharge increases decrease with decreasing event frequency and statistically significant ( = 0.05) increases in peak flow are confined to events with a 1 year or lower return period. For a range of return periods from 0.17 to 20 years, the effect (i
Cohen, Sagy; Willgoose, Garry; Hancock, Greg
2009-09-01
Hillslope surface armouring and weathering processes have received little attention in geomorphologic and hydrologic models due to their complexity and the uncertainty associated with them. Their importance, however, in a wide range of spatial processes is well recognized. A physically based armouring and weathering computer model (ARMOUR) has previously been used to successfully simulate the effect of these processes on erosion and soil grading at a hillslope scale. This model is, however, computationally complex and cannot realistically be applied over large areas or over long periods of time. A simplified process conceptualization approach is presented (named mARM) which uses a novel approach of modeling physical processes using transition matrices, which is orders of magnitude faster. We describe in detail the modeling framework. We calibrate and evaluate the model against ARMOUR simulations and show it matches ARMOUR for a range of conditions. The computational efficiency of mARM allowed us to easily examine time- and space-varying relationships between erosion and physical weathering rates at the hillslope scale. For erosion-dominated slopes the surface coarsens over time, while for weathering domination the surface fines over time. When erosion and weathering are comparable in scale a slope can be weathering-dominated upslope (where runoff and therefore erosion is low) and armouring-dominated downslope. In all cases, for a constant gradient slope the surface armour coarsens downslope as a result of a balance between erosion and weathering. Thus even for weathering-dominated slopes the surface grading catena is dependent on armouring through the balance between weathering and armouring. We also observed that for many slopes the surface initially armours but, after some period of time (space- and rate-dependent), weathering begins to dominate and the surface subsequently fines. Depending on the relative magnitude of armouring and weathering the final
Blyth, T S
2002-01-01
Most of the introductory courses on linear algebra develop the basic theory of finite dimensional vector spaces, and in so doing relate the notion of a linear mapping to that of a matrix. Generally speaking, such courses culminate in the diagonalisation of certain matrices and the application of this process to various situations. Such is the case, for example, in our previous SUMS volume Basic Linear Algebra. The present text is a continuation of that volume, and has the objective of introducing the reader to more advanced properties of vector spaces and linear mappings, and consequently of matrices. For readers who are not familiar with the contents of Basic Linear Algebra we provide an introductory chapter that consists of a compact summary of the prerequisites for the present volume. In order to consolidate the student's understanding we have included a large num ber of illustrative and worked examples, as well as many exercises that are strategi cally placed throughout the text. Solutions to the ex...
Camporese, M.; Botto, A.
2017-12-01
Data assimilation is becoming increasingly popular in hydrological and earth system modeling, as it allows for direct integration of multisource observation data in modeling predictions and uncertainty reduction. For this reason, data assimilation has been recently the focus of much attention also for integrated surface-subsurface hydrological models, whereby multiple terrestrial compartments (e.g., snow cover, surface water, groundwater) are solved simultaneously, in an attempt to tackle environmental problems in a holistic approach. Recent examples include the joint assimilation of water table, soil moisture, and river discharge measurements in catchment models of coupled surface-subsurface flow using the ensemble Kalman filter (EnKF). Although the EnKF has been specifically developed to deal with nonlinear models, integrated hydrological models based on the Richards equation still represent a challenge, due to strong nonlinearities that may significantly affect the filter performance. Thus, more studies are needed to investigate the capabilities of EnKF to correct the system state and identify parameters in cases where the unsaturated zone dynamics are dominant. Here, the model CATHY (CATchment HYdrology) is applied to reproduce the hydrological dynamics observed in an experimental hillslope, equipped with tensiometers, water content reflectometer probes, and tipping bucket flow gages to monitor the hillslope response to a series of artificial rainfall events. We assimilate pressure head, soil moisture, and subsurface outflow with EnKF in a number of assimilation scenarios and discuss the challenges, issues, and tradeoffs arising from the assimilation of multisource data in a real-world test case, with particular focus on the capability of DA to update the subsurface parameters.
Mamyrin, B.A.; Shmikk, D.V.
1979-01-01
A description and operating principle of a linear mass reflectron with V-form trajectory of ion motion -a new non-magnetic time-of-flight mass spectrometer with high resolution are presented. The ion-optical system of the device consists of an ion source with ionization by electron shock, of accelerating gaps, reflector gaps, a drift space and ion detector. Ions move in the linear mass refraction along the trajectories parallel to the axis of the analyzer chamber. The results of investigations into the experimental device are given. With an ion drift length of 0.6 m the device resolution is 1200 with respect to the peak width at half-height. Small-sized mass spectrometric transducers with high resolution and sensitivity may be designed on the base of the linear mass reflectron principle
Olver, Peter J
2018-01-01
This textbook develops the essential tools of linear algebra, with the goal of imparting technique alongside contextual understanding. Applications go hand-in-hand with theory, each reinforcing and explaining the other. This approach encourages students to develop not only the technical proficiency needed to go on to further study, but an appreciation for when, why, and how the tools of linear algebra can be used across modern applied mathematics. Providing an extensive treatment of essential topics such as Gaussian elimination, inner products and norms, and eigenvalues and singular values, this text can be used for an in-depth first course, or an application-driven second course in linear algebra. In this second edition, applications have been updated and expanded to include numerical methods, dynamical systems, data analysis, and signal processing, while the pedagogical flow of the core material has been improved. Throughout, the text emphasizes the conceptual connections between each application and the un...
Banach, S
1987-01-01
This classic work by the late Stefan Banach has been translated into English so as to reach a yet wider audience. It contains the basics of the algebra of operators, concentrating on the study of linear operators, which corresponds to that of the linear forms a1x1 + a2x2 + ... + anxn of algebra.The book gathers results concerning linear operators defined in general spaces of a certain kind, principally in Banach spaces, examples of which are: the space of continuous functions, that of the pth-power-summable functions, Hilbert space, etc. The general theorems are interpreted in various mathematical areas, such as group theory, differential equations, integral equations, equations with infinitely many unknowns, functions of a real variable, summation methods and orthogonal series.A new fifty-page section (``Some Aspects of the Present Theory of Banach Spaces'''') complements this important monograph.
Høskuldsson, Agnar
1996-01-01
Determination of the proper dimension of a given linear model is one of the most important tasks in the applied modeling work. We consider here eight criteria that can be used to determine the dimension of the model, or equivalently, the number of components to use in the model. Four of these cri......Determination of the proper dimension of a given linear model is one of the most important tasks in the applied modeling work. We consider here eight criteria that can be used to determine the dimension of the model, or equivalently, the number of components to use in the model. Four...... the basic problems in determining the dimension of linear models. Then each of the eight measures are treated. The results are illustrated by examples....
Linear programming using Matlab
Ploskas, Nikolaos
2017-01-01
This book offers a theoretical and computational presentation of a variety of linear programming algorithms and methods with an emphasis on the revised simplex method and its components. A theoretical background and mathematical formulation is included for each algorithm as well as comprehensive numerical examples and corresponding MATLAB® code. The MATLAB® implementations presented in this book are sophisticated and allow users to find solutions to large-scale benchmark linear programs. Each algorithm is followed by a computational study on benchmark problems that analyze the computational behavior of the presented algorithms. As a solid companion to existing algorithmic-specific literature, this book will be useful to researchers, scientists, mathematical programmers, and students with a basic knowledge of linear algebra and calculus. The clear presentation enables the reader to understand and utilize all components of simplex-type methods, such as presolve techniques, scaling techniques, pivoting ru...
Anon.
1994-01-01
The aim of the TESLA (TeV Superconducting Linear Accelerator) collaboration (at present 19 institutions from seven countries) is to establish the technology for a high energy electron-positron linear collider using superconducting radiofrequency cavities to accelerate its beams. Another basic goal is to demonstrate that such a collider can meet its performance goals in a cost effective manner. For this the TESLA collaboration is preparing a 500 MeV superconducting linear test accelerator at the DESY Laboratory in Hamburg. This TTF (TESLA Test Facility) consists of four cryomodules, each approximately 12 m long and containing eight 9-cell solid niobium cavities operating at a frequency of 1.3 GHz
Linearly Adjustable International Portfolios
Fonseca, R. J.; Kuhn, D.; Rustem, B.
2010-09-01
We present an approach to multi-stage international portfolio optimization based on the imposition of a linear structure on the recourse decisions. Multiperiod decision problems are traditionally formulated as stochastic programs. Scenario tree based solutions however can become intractable as the number of stages increases. By restricting the space of decision policies to linear rules, we obtain a conservative tractable approximation to the original problem. Local asset prices and foreign exchange rates are modelled separately, which allows for a direct measure of their impact on the final portfolio value.
Linearly Adjustable International Portfolios
Fonseca, R. J.; Kuhn, D.; Rustem, B.
2010-01-01
We present an approach to multi-stage international portfolio optimization based on the imposition of a linear structure on the recourse decisions. Multiperiod decision problems are traditionally formulated as stochastic programs. Scenario tree based solutions however can become intractable as the number of stages increases. By restricting the space of decision policies to linear rules, we obtain a conservative tractable approximation to the original problem. Local asset prices and foreign exchange rates are modelled separately, which allows for a direct measure of their impact on the final portfolio value.
Barkman, W.E.; Adams, W.Q.; Berrier, B.R.
1978-01-01
A linear induction motor has been operated on a test bed with a feedback pulse resolution of 5 nm (0.2 μin). Slewing tests with this slide drive have shown positioning errors less than or equal to 33 nm (1.3 μin) at feedrates between 0 and 25.4 mm/min (0-1 ipm). A 0.86-m (34-in)-stroke linear motor is being investigated, using the SPACO machine as a test bed. Initial results were encouraging, and work is continuing to optimize the servosystem compensation
Hogben, Leslie
2013-01-01
With a substantial amount of new material, the Handbook of Linear Algebra, Second Edition provides comprehensive coverage of linear algebra concepts, applications, and computational software packages in an easy-to-use format. It guides you from the very elementary aspects of the subject to the frontiers of current research. Along with revisions and updates throughout, the second edition of this bestseller includes 20 new chapters.New to the Second EditionSeparate chapters on Schur complements, additional types of canonical forms, tensors, matrix polynomials, matrix equations, special types of
Linear Algebra Thoroughly Explained
Vujičić, Milan
2008-01-01
Linear Algebra Thoroughly Explained provides a comprehensive introduction to the subject suitable for adoption as a self-contained text for courses at undergraduate and postgraduate level. The clear and comprehensive presentation of the basic theory is illustrated throughout with an abundance of worked examples. The book is written for teachers and students of linear algebra at all levels and across mathematics and the applied sciences, particularly physics and engineering. It will also be an invaluable addition to research libraries as a comprehensive resource book for the subject.
2013-05-10
AND VICTIM- ~ vAP BLAMING 4. AMERICA, LINEARLY CYCUCAL AF IMT 1768, 19840901, V5 PREVIOUS EDITION WILL BE USED. C2C Jessica Adams Dr. Brissett...his desires, his failings, and his aspirations follow the same general trend throughout history and throughout cultures. The founding fathers sought
Southworth, B.
1985-01-01
The peak of the construction phase of the Stanford Linear Collider, SLC, to achieve 50 GeV electron-positron collisions has now been passed. The work remains on schedule to attempt colliding beams, initially at comparatively low luminosity, early in 1987. (orig./HSI).
Mafra Neto, F.
1992-01-01
The dose of gamma radiation from a linear source of cesium 137 is obtained, presenting two difficulties: oblique filtration of radiation when cross the platinum wall, in different directions, and dose connection due to the scattering by the material mean of propagation. (C.G.C.)
Resistors Improve Ramp Linearity
Kleinberg, L. L.
1982-01-01
Simple modification to bootstrap ramp generator gives more linear output over longer sweep times. New circuit adds just two resistors, one of which is adjustable. Modification cancels nonlinearities due to variations in load on charging capacitor and due to changes in charging current as the voltage across capacitor increases.
LINEAR COLLIDERS: 1992 workshop
Settles, Ron; Coignet, Guy
1992-01-01
As work on designs for future electron-positron linear colliders pushes ahead at major Laboratories throughout the world in a major international collaboration framework, the LC92 workshop held in Garmisch Partenkirchen this summer, attended by 200 machine and particle physicists, provided a timely focus
Brameier, Markus
2007-01-01
Presents a variant of Genetic Programming that evolves imperative computer programs as linear sequences of instructions, in contrast to the more traditional functional expressions or syntax trees. This book serves as a reference for researchers, but also contains sufficient introduction for students and those who are new to the field
Dobbs, David E.
2013-01-01
A direct method is given for solving first-order linear recurrences with constant coefficients. The limiting value of that solution is studied as "n to infinity." This classroom note could serve as enrichment material for the typical introductory course on discrete mathematics that follows a calculus course.
Takeda, Seishi
1992-01-01
The status of R and D of future e + e - linear colliders proposed by the institutions throughout the world is described including the JLC, NLC, VLEPP, CLIC, DESY/THD and TESLA projects. The parameters and RF sources are discussed. (G.P.) 36 refs.; 1 tab
Finite-dimensional linear algebra
Gockenbach, Mark S
2010-01-01
Some Problems Posed on Vector SpacesLinear equationsBest approximationDiagonalizationSummaryFields and Vector SpacesFields Vector spaces Subspaces Linear combinations and spanning sets Linear independence Basis and dimension Properties of bases Polynomial interpolation and the Lagrange basis Continuous piecewise polynomial functionsLinear OperatorsLinear operatorsMore properties of linear operatorsIsomorphic vector spaces Linear operator equations Existence and uniqueness of solutions The fundamental theorem; inverse operatorsGaussian elimination Newton's method Linear ordinary differential eq
Linearity and Non-linearity of Photorefractive effect in Materials ...
In this paper we have studied the Linearity and Non-linearity of Photorefractive effect in materials using the band transport model. For low light beam intensities the change in the refractive index is proportional to the electric field for linear optics while for non- linear optics the change in refractive index is directly proportional ...
Linearly Refined Session Types
Pedro Baltazar
2012-11-01
Full Text Available Session types capture precise protocol structure in concurrent programming, but do not specify properties of the exchanged values beyond their basic type. Refinement types are a form of dependent types that can address this limitation, combining types with logical formulae that may refer to program values and can constrain types using arbitrary predicates. We present a pi calculus with assume and assert operations, typed using a session discipline that incorporates refinement formulae written in a fragment of Multiplicative Linear Logic. Our original combination of session and refinement types, together with the well established benefits of linearity, allows very fine-grained specifications of communication protocols in which refinement formulae are treated as logical resources rather than persistent truths.
Kuznetsov, N.; Maz'ya, V.; Vainberg, B.
2002-08-01
This book gives a self-contained and up-to-date account of mathematical results in the linear theory of water waves. The study of waves has many applications, including the prediction of behavior of floating bodies (ships, submarines, tension-leg platforms etc.), the calculation of wave-making resistance in naval architecture, and the description of wave patterns over bottom topography in geophysical hydrodynamics. The first section deals with time-harmonic waves. Three linear boundary value problems serve as the approximate mathematical models for these types of water waves. The next section uses a plethora of mathematical techniques in the investigation of these three problems. The techniques used in the book include integral equations based on Green's functions, various inequalities between the kinetic and potential energy and integral identities which are indispensable for proving the uniqueness theorems. The so-called inverse procedure is applied to constructing examples of non-uniqueness, usually referred to as 'trapped nodes.'
The International Linear Collider
List Benno
2014-04-01
Full Text Available The International Linear Collider (ILC is a proposed e+e− linear collider with a centre-of-mass energy of 200–500 GeV, based on superconducting RF cavities. The ILC would be an ideal machine for precision studies of a light Higgs boson and the top quark, and would have a discovery potential for new particles that is complementary to that of LHC. The clean experimental conditions would allow the operation of detectors with extremely good performance; two such detectors, ILD and SiD, are currently being designed. Both make use of novel concepts for tracking and calorimetry. The Japanese High Energy Physics community has recently recommended to build the ILC in Japan.
The International Linear Collider
List, Benno
2014-04-01
The International Linear Collider (ILC) is a proposed e+e- linear collider with a centre-of-mass energy of 200-500 GeV, based on superconducting RF cavities. The ILC would be an ideal machine for precision studies of a light Higgs boson and the top quark, and would have a discovery potential for new particles that is complementary to that of LHC. The clean experimental conditions would allow the operation of detectors with extremely good performance; two such detectors, ILD and SiD, are currently being designed. Both make use of novel concepts for tracking and calorimetry. The Japanese High Energy Physics community has recently recommended to build the ILC in Japan.
Høskuldsson, Agnar
1996-01-01
Determination of the proper dimension of a given linear model is one of the most important tasks in the applied modeling work. We consider here eight criteria that can be used to determine the dimension of the model, or equivalently, the number of components to use in the model. Four...... the basic problems in determining the dimension of linear models. Then each of the eight measures are treated. The results are illustrated by examples....... of these criteria are widely used ones, while the remaining four are ones derived from the H-principle of mathematical modeling. Many examples from practice show that the criteria derived from the H-principle function better than the known and popular criteria for the number of components. We shall briefly review...
Goldowsky, Michael P. (Inventor)
1987-01-01
A reciprocating linear motor is formed with a pair of ring-shaped permanent magnets having opposite radial polarizations, held axially apart by a nonmagnetic yoke, which serves as an axially displaceable armature assembly. A pair of annularly wound coils having axial lengths which differ from the axial lengths of the permanent magnets are serially coupled together in mutual opposition and positioned with an outer cylindrical core in axial symmetry about the armature assembly. One embodiment includes a second pair of annularly wound coils serially coupled together in mutual opposition and an inner cylindrical core positioned in axial symmetry inside the armature radially opposite to the first pair of coils. Application of a potential difference across a serial connection of the two pairs of coils creates a current flow perpendicular to the magnetic field created by the armature magnets, thereby causing limited linear displacement of the magnets relative to the coils.
Henneaux, Marc; Teitelboim, Claudio
2005-01-01
We show that duality transformations of linearized gravity in four dimensions, i.e., rotations of the linearized Riemann tensor and its dual into each other, can be extended to the dynamical fields of the theory so as to be symmetries of the action and not just symmetries of the equations of motion. Our approach relies on the introduction of two superpotentials, one for the spatial components of the spin-2 field and the other for their canonically conjugate momenta. These superpotentials are two-index, symmetric tensors. They can be taken to be the basic dynamical fields and appear locally in the action. They are simply rotated into each other under duality. In terms of the superpotentials, the canonical generator of duality rotations is found to have a Chern-Simons-like structure, as in the Maxwell case
Phinney, N.
1992-01-01
The SLAC Linear Collider has begun a new era of operation with the SLD detector. During 1991 there was a first engineering run for the SLD in parallel with machine improvements to increase luminosity and reliability. For the 1992 run, a polarized electron source was added and more than 10,000 Zs with an average of 23% polarization have been logged by the SLD. This paper discusses the performance of the SLC in 1991 and 1992 and the technical advances that have produced higher luminosity. Emphasis will be placed on issues relevant to future linear colliders such as producing and maintaining high current, low emittance beams and focusing the beams to the micron scale for collisions. (Author) tab., 2 figs., 18 refs
Linear waves and instabilities
Bers, A.
1975-01-01
The electrodynamic equations for small-amplitude waves and their dispersion relation in a homogeneous plasma are outlined. For such waves, energy and momentum, and their flow and transformation, are described. Perturbation theory of waves is treated and applied to linear coupling of waves, and the resulting instabilities from such interactions between active and passive waves. Linear stability analysis in time and space is described where the time-asymptotic, time-space Green's function for an arbitrary dispersion relation is developed. The perturbation theory of waves is applied to nonlinear coupling, with particular emphasis on pump-driven interactions of waves. Details of the time--space evolution of instabilities due to coupling are given. (U.S.)
Extended linear chain compounds
Linear chain substances span a large cross section of contemporary chemistry ranging from covalent polymers, to organic charge transfer com plexes to nonstoichiometric transition metal coordination complexes. Their commonality, which coalesced intense interest in the theoretical and exper imental solid state physics/chemistry communities, was based on the obser vation that these inorganic and organic polymeric substrates exhibit striking metal-like electrical and optical properties. Exploitation and extension of these systems has led to the systematic study of both the chemistry and physics of highly and poorly conducting linear chain substances. To gain a salient understanding of these complex materials rich in anomalous aniso tropic electrical, optical, magnetic, and mechanical properties, the conver gence of diverse skills and talents was required. The constructive blending of traditionally segregated disciplines such as synthetic and physical organic, inorganic, and polymer chemistry, crystallog...
Diamond, Jared M.
1966-01-01
1. The relation between osmotic gradient and rate of osmotic water flow has been measured in rabbit gall-bladder by a gravimetric procedure and by a rapid method based on streaming potentials. Streaming potentials were directly proportional to gravimetrically measured water fluxes. 2. As in many other tissues, water flow was found to vary with gradient in a markedly non-linear fashion. There was no consistent relation between the water permeability and either the direction or the rate of water flow. 3. Water flow in response to a given gradient decreased at higher osmolarities. The resistance to water flow increased linearly with osmolarity over the range 186-825 m-osM. 4. The resistance to water flow was the same when the gall-bladder separated any two bathing solutions with the same average osmolarity, regardless of the magnitude of the gradient. In other words, the rate of water flow is given by the expression (Om — Os)/[Ro′ + ½k′ (Om + Os)], where Ro′ and k′ are constants and Om and Os are the bathing solution osmolarities. 5. Of the theories advanced to explain non-linear osmosis in other tissues, flow-induced membrane deformations, unstirred layers, asymmetrical series-membrane effects, and non-osmotic effects of solutes could not explain the results. However, experimental measurements of water permeability as a function of osmolarity permitted quantitative reconstruction of the observed water flow—osmotic gradient curves. Hence non-linear osmosis in rabbit gall-bladder is due to a decrease in water permeability with increasing osmolarity. 6. The results suggest that aqueous channels in the cell membrane behave as osmometers, shrinking in concentrated solutions of impermeant molecules and thereby increasing membrane resistance to water flow. A mathematical formulation of such a membrane structure is offered. PMID:5945254
Fundamentals of linear algebra
Dash, Rajani Ballav
2008-01-01
FUNDAMENTALS OF LINEAR ALGEBRA is a comprehensive Text Book, which can be used by students and teachers of All Indian Universities. The Text has easy, understandable form and covers all topics of UGC Curriculum. There are lots of worked out examples which helps the students in solving the problems without anybody's help. The Problem sets have been designed keeping in view of the questions asked in different examinations.
Sander, K F
1964-01-01
Linear Network Theory covers the significant algebraic aspect of network theory, with minimal reference to practical circuits. The book begins the presentation of network analysis with the exposition of networks containing resistances only, and follows it up with a discussion of networks involving inductance and capacity by way of the differential equations. Classification and description of certain networks, equivalent networks, filter circuits, and network functions are also covered. Electrical engineers, technicians, electronics engineers, electricians, and students learning the intricacies
Non linear viscoelastic models
Agerkvist, Finn T.
2011-01-01
Viscoelastic eects are often present in loudspeaker suspensions, this can be seen in the displacement transfer function which often shows a frequency dependent value below the resonance frequency. In this paper nonlinear versions of the standard linear solid model (SLS) are investigated....... The simulations show that the nonlinear version of the Maxwell SLS model can result in a time dependent small signal stiness while the Kelvin Voight version does not....
Relativistic Linear Restoring Force
Clark, D.; Franklin, J.; Mann, N.
2012-01-01
We consider two different forms for a relativistic version of a linear restoring force. The pair comes from taking Hooke's law to be the force appearing on the right-hand side of the relativistic expressions: d"p"/d"t" or d"p"/d["tau"]. Either formulation recovers Hooke's law in the non-relativistic limit. In addition to these two forces, we…
Superconducting linear colliders
Anon.
1990-01-01
The advantages of superconducting radiofrequency (SRF) for particle accelerators have been demonstrated by successful operation of systems in the TRISTAN and LEP electron-positron collider rings respectively at the Japanese KEK Laboratory and at CERN. If performance continues to improve and costs can be lowered, this would open an attractive option for a high luminosity TeV (1000 GeV) linear collider
Perturbed asymptotically linear problems
Bartolo, R.; Candela, A. M.; Salvatore, A.
2012-01-01
The aim of this paper is investigating the existence of solutions of some semilinear elliptic problems on open bounded domains when the nonlinearity is subcritical and asymptotically linear at infinity and there is a perturbation term which is just continuous. Also in the case when the problem has not a variational structure, suitable procedures and estimates allow us to prove that the number of distinct crtitical levels of the functional associated to the unperturbed problem is "stable" unde...
Miniature linear cooler development
Pruitt, G.R.
1993-01-01
An overview is presented of the status of a family of miniature linear coolers currently under development by Hughes Aircraft Co. for use in hand held, volume limited or power limited infrared applications. These coolers, representing the latest additions to the Hughes family of TOP trademark [twin-opposed piston] linear coolers, have been fabricated and tested in three different configurations. Each configuration is designed to utilize a common compressor assembly resulting in reduced manufacturing costs. The baseline compressor has been integrated with two different expander configurations and has been operated with two different levels of input power. These various configuration combinations offer a wide range of performance and interface characteristics which may be tailored to applications requiring limited power and size without significantly compromising cooler capacity or cooldown characteristics. Key cooler characteristics and test data are summarized for three combinations of cooler configurations which are representative of the versatility of this linear cooler design. Configurations reviewed include the shortened coldfinger [1.50 to 1.75 inches long], limited input power [less than 17 Watts] for low power availability applications; the shortened coldfinger with higher input power for lightweight, higher performance applications; and coldfingers compatible with DoD 0.4 Watt Common Module coolers for wider range retrofit capability. Typical weight of these miniature linear coolers is less than 500 grams for the compressor, expander and interconnecting transfer line. Cooling capacity at 80K at room ambient conditions ranges from 400 mW to greater than 550 mW. Steady state power requirements for maintaining a heat load of 150 mW at 80K has been shown to be less than 8 Watts. Ongoing reliability growth testing is summarized including a review of the latest test article results
Avram Mihai
2017-01-01
Full Text Available The paper presents a linear pneumatic actuator with short working stroke. It consists of a pneumatic motor (a simple stroke cylinder or a membrane chamber, two 2/2 pneumatic distributors “all or nothing” electrically commanded for controlling the intake/outtake flow to/from the active chamber of the motor, a position transducer and a microcontroller. There is also presented the theoretical analysis (mathematical modelling and numerical simulation accomplished.
Avram Mihai; Niţu Constantin; Bucşan Constantin; Grămescu Bogdan
2017-01-01
The paper presents a linear pneumatic actuator with short working stroke. It consists of a pneumatic motor (a simple stroke cylinder or a membrane chamber), two 2/2 pneumatic distributors “all or nothing” electrically commanded for controlling the intake/outtake flow to/from the active chamber of the motor, a position transducer and a microcontroller. There is also presented the theoretical analysis (mathematical modelling and numerical simulation) accomplished.
Scheffel, J.
1984-03-01
The linear Grad-Shafranov equation for a toroidal, axisymmetric plasma is solved analytically. Exact solutions are given in terms of confluent hyper-geometric functions. As an alternative, simple and accurate WKBJ solutions are presented. With parabolic pressure profiles, both hollow and peaked toroidal current density profiles are obtained. As an example the equilibrium of a z-pinch with a square-shaped cross section is derived.(author)
Buttram, M.T.; Ginn, J.W.
1988-06-21
A linear induction accelerator includes a plurality of adder cavities arranged in a series and provided in a structure which is evacuated so that a vacuum inductance is provided between each adder cavity and the structure. An energy storage system for the adder cavities includes a pulsed current source and a respective plurality of bipolar converting networks connected thereto. The bipolar high-voltage, high-repetition-rate square pulse train sets and resets the cavities. 4 figs.
Springer, T A
1998-01-01
"[The first] ten chapters...are an efficient, accessible, and self-contained introduction to affine algebraic groups over an algebraically closed field. The author includes exercises and the book is certainly usable by graduate students as a text or for self-study...the author [has a] student-friendly style… [The following] seven chapters... would also be a good introduction to rationality issues for algebraic groups. A number of results from the literature…appear for the first time in a text." –Mathematical Reviews (Review of the Second Edition) "This book is a completely new version of the first edition. The aim of the old book was to present the theory of linear algebraic groups over an algebraically closed field. Reading that book, many people entered the research field of linear algebraic groups. The present book has a wider scope. Its aim is to treat the theory of linear algebraic groups over arbitrary fields. Again, the author keeps the treatment of prerequisites self-contained. The material of t...
Parametric Linear Dynamic Logic
Peter Faymonville
2014-08-01
Full Text Available We introduce Parametric Linear Dynamic Logic (PLDL, which extends Linear Dynamic Logic (LDL by temporal operators equipped with parameters that bound their scope. LDL was proposed as an extension of Linear Temporal Logic (LTL that is able to express all ω-regular specifications while still maintaining many of LTL's desirable properties like an intuitive syntax and a translation into non-deterministic Büchi automata of exponential size. But LDL lacks capabilities to express timing constraints. By adding parameterized operators to LDL, we obtain a logic that is able to express all ω-regular properties and that subsumes parameterized extensions of LTL like Parametric LTL and PROMPT-LTL. Our main technical contribution is a translation of PLDL formulas into non-deterministic Büchi word automata of exponential size via alternating automata. This yields a PSPACE model checking algorithm and a realizability algorithm with doubly-exponential running time. Furthermore, we give tight upper and lower bounds on optimal parameter values for both problems. These results show that PLDL model checking and realizability are not harder than LTL model checking and realizability.
Quantum linear Boltzmann equation
Vacchini, Bassano; Hornberger, Klaus
2009-01-01
We review the quantum version of the linear Boltzmann equation, which describes in a non-perturbative fashion, by means of scattering theory, how the quantum motion of a single test particle is affected by collisions with an ideal background gas. A heuristic derivation of this Lindblad master equation is presented, based on the requirement of translation-covariance and on the relation to the classical linear Boltzmann equation. After analyzing its general symmetry properties and the associated relaxation dynamics, we discuss a quantum Monte Carlo method for its numerical solution. We then review important limiting forms of the quantum linear Boltzmann equation, such as the case of quantum Brownian motion and pure collisional decoherence, as well as the application to matter wave optics. Finally, we point to the incorporation of quantum degeneracies and self-interactions in the gas by relating the equation to the dynamic structure factor of the ambient medium, and we provide an extension of the equation to include internal degrees of freedom.
Emma, P.
1995-01-01
The Stanford Linear Collider (SLC) is the first and only high-energy e + e - linear collider in the world. Its most remarkable features are high intensity, submicron sized, polarized (e - ) beams at a single interaction point. The main challenges posed by these unique characteristics include machine-wide emittance preservation, consistent high intensity operation, polarized electron production and transport, and the achievement of a high degree of beam stability on all time scales. In addition to serving as an important machine for the study of Z 0 boson production and decay using polarized beams, the SLC is also an indispensable source of hands-on experience for future linear colliders. Each new year of operation has been highlighted with a marked improvement in performance. The most significant improvements for the 1994-95 run include new low impedance vacuum chambers for the damping rings, an upgrade to the optics and diagnostics of the final focus systems, and a higher degree of polarization from the electron source. As a result, the average luminosity has nearly doubled over the previous year with peaks approaching 10 30 cm -2 s -1 and an 80% electron polarization at the interaction point. These developments as well as the remaining identifiable performance limitations will be discussed
Römer, Wolfgang
2008-08-01
In southern São Paulo the Serra do Mar is characterized by three distinct terrain types: 1) highly dissected areas with closely spaced ridges and accordant summit heights; 2) multiconvex hills; and 3) terrains with highly elevated watershed areas, irregular summit heights, and locally subdued relief. The development of this landscape is considered to be the result of the Cenozoic block-faulting and of the influences that are exerted by the differing lithological and structural setting of block-faulted compartments on weathering and erosion processes. In areas characterized by pronounced accordant summits the close coincidence between hillslope angle and the angle of limiting stability against landsliding points to a close adjustment of hillslope gradients and the mechanical properties of the regolith. The relative height of the hillslopes is functionally related to the spacing of the valleys and the gradient of the hillslopes. In areas with a regular spacing of v-shaped valleys and uniform rocks, this leads to the intersection of valley-side slopes in summits and ridges at a certain elevation. This elevation is determined by the length and steepness of the valley-side slopes. Therefore, the heights of the summits are geometrically constrained and are likely to indicate the upper limit of summit heights or an "upper denudation level" that is adjusted by hillslope processes to the incising streams. Accordant summit heights of this type are poor indicators of formerly more extensive denudation surfaces as it is also likely that they are a result of the long-term adjustment of hillslopes to river incision. The steep mountain flanks of block-faulted compartments on the other hand, comprise regolith-covered hillslopes that are closely adjusted to the maximum stable gradient as well as rock-slopes that are controlled by the rock-mass strength. Their summits are usually not accommodated into uniform summit levels. Highly elevated watershed areas exhibiting a subdued
Garbet, X.; Mourgues, F.; Samain, A.
1987-01-01
Among the various instabilities which could explain the anomalous electron heat transport observed in tokamaks during additional heating, a microtearing turbulence is a reasonable candidate since it affects directly the magnetic topology. This turbulence may be described in a proper frame rotating around the majors axis by a static potential vector. In strong non linear regimes, the flow of electrons along the stochastic field lines induces a current. The point is to know whether this current can sustain the turbulence. The mechanisms of this self-consistency, involving the combined effects of the thermal diamagnetism and of the electric drift are presented here
Wangler, Thomas P
2008-01-01
Thomas P. Wangler received his B.S. degree in physics from Michigan State University, and his Ph.D. degree in physics and astronomy from the University of Wisconsin. After postdoctoral appointments at the University of Wisconsin and Brookhaven National Laboratory, he joined the staff of Argonne National Laboratory in 1966, working in the fields of experimental high-energy physics and accelerator physics. He joined the Accelerator Technology Division at Los Alamos National Laboratory in 1979, where he specialized in high-current beam physics and linear accelerator design and technology. In 2007
Richter, B.; Bell, R.A.; Brown, K.L.
1980-06-01
The SLAC LINEAR COLLIDER is designed to achieve an energy of 100 GeV in the electron-positron center-of-mass system by accelerating intense bunches of particles in the SLAC linac and transporting the electron and positron bunches in a special magnet system to a point where they are focused to a radius of about 2 microns and made to collide head on. The rationale for this new type of colliding beam system is discussed, the project is described, some of the novel accelerator physics issues involved are discussed, and some of the critical technical components are described
Lopez, Cesar
2014-01-01
MATLAB is a high-level language and environment for numerical computation, visualization, and programming. Using MATLAB, you can analyze data, develop algorithms, and create models and applications. The language, tools, and built-in math functions enable you to explore multiple approaches and reach a solution faster than with spreadsheets or traditional programming languages, such as C/C++ or Java. MATLAB Linear Algebra introduces you to the MATLAB language with practical hands-on instructions and results, allowing you to quickly achieve your goals. In addition to giving an introduction to
Hazenberg, P.; Broxton, P. D.; Brunke, M.; Gochis, D.; Niu, G. Y.; Pelletier, J. D.; Troch, P. A. A.; Zeng, X.
2015-12-01
The terrestrial hydrological system, including surface and subsurface water, is an essential component of the Earth's climate system. Over the past few decades, land surface modelers have built one-dimensional (1D) models resolving the vertical flow of water through the soil column for use in Earth system models (ESMs). These models generally have a relatively coarse model grid size (~25-100 km) and only account for sub-grid lateral hydrological variations using simple parameterization schemes. At the same time, hydrologists have developed detailed high-resolution (~0.1-10 km grid size) three dimensional (3D) models and showed the importance of accounting for the vertical and lateral redistribution of surface and subsurface water on soil moisture, the surface energy balance and ecosystem dynamics on these smaller scales. However, computational constraints have limited the implementation of the high-resolution models for continental and global scale applications. The current work presents a hybrid-3D hydrological approach is presented, where the 1D vertical soil column model (available in many ESMs) is coupled with a high-resolution lateral flow model (h2D) to simulate subsurface flow and overland flow. H2D accounts for both local-scale hillslope and regional-scale unconfined aquifer responses (i.e. riparian zone and wetlands). This approach was shown to give comparable results as those obtained by an explicit 3D Richards model for the subsurface, but improves runtime efficiency considerably. The h3D approach is implemented for the Delaware river basin, where Noah-MP land surface model (LSM) is used to calculated vertical energy and water exchanges with the atmosphere using a 10km grid resolution. Noah-MP was coupled within the WRF-Hydro infrastructure with the lateral 1km grid resolution h2D model, for which the average depth-to-bedrock, hillslope width function and soil parameters were estimated from digital datasets. The ability of this h3D approach to simulate
Teo, E. K.; Beganskas, S.; Young, K. S.; Weir, W. B.; Harmon, R. E.; Lozano, S.; Fisher, A. T.
2017-12-01
Many aquifer systems in central coastal California face a triple threat of excess demand, changing land use, and a shifting climate. These last two factors can contribute to reductions in groundwater recharge. Managed aquifer recharge using distributed stormwater collection (DSC-MAR) is an adaptation technique for collecting excess stormwater runoff from hillslopes for infiltration into underlying aquifers, before that water reaches a "blue line" stream. We are developing a decision support system (DSS) that combines surface and subsurface hydrogeological data with high-resolution predictions of hillslope runoff, with specific application to Santa Cruz and northern Monterey Counties. Other studies presented at AGU will focus on the northern and southern parts of our study region (San Lorenzo River Basin, Lower Pajaro River Basin). This presentation focuses on mid-Santa Cruz County, including the Soquel-Aptos Groundwater Basin. The DSS uses a geographic information system to compile and merge data from numerous local, state, and federal sources to identify locations on the landscape where DSC-MAR may be most suitable. This requires classification of disparate data types so that they can be combined. Stormwater runoff for individual river basins in the study region was simulated using historical streamflow data for calibration and validation. Both analyses were completed with relatively fine resolution, from 10 m2 pixels for elevation to 0.1-1.0 km hydrologic response units for properties such as soil and vegetation properties. Future climate is uncertain, so we used historical data to create a catalog of dry, normal, and wet hydrologic conditions, then created synthetic future climate scenarios for simulation. The DDS shows that there are numerous regions in mid-Santa Cruz County where there is a confluence of MAR suitability and the generation of stormwater runoff that could supply recharge projects (with a nominal target of 100 ac-ft/yr of infiltration), even
Special set linear algebra and special set fuzzy linear algebra
Kandasamy, W. B. Vasantha; Smarandache, Florentin; Ilanthenral, K.
2009-01-01
The authors in this book introduce the notion of special set linear algebra and special set fuzzy Linear algebra, which is an extension of the notion set linear algebra and set fuzzy linear algebra. These concepts are best suited in the application of multi expert models and cryptology. This book has five chapters. In chapter one the basic concepts about set linear algebra is given in order to make this book a self contained one. The notion of special set linear algebra and their fuzzy analog...
Munehiro, H
1980-05-29
When driving the carriage of a printer through a rotating motor, there are problems regarding the limited accuracy of the carriage position due to rotation or contraction and ageing of the cable. In order to solve the problem, a direct drive system was proposed, in which the printer carriage is driven by a linear motor. If one wants to keep the motor circuit of such a motor compact, then the magnetic flux density in the air gap must be reduced or the motor travel must be reduced. It is the purpose of this invention to create an electrodynamic linear motor, which on the one hand is compact and light and on the other hand has a relatively high constant force over a large travel. The invention is characterised by the fact that magnetic fields of alternating polarity are generated at equal intervals in the magnetic field, and that the coil arrangement has 2 adjacent coils, whose size corresponds to half the length of each magnetic pole. A logic circuit is provided to select one of the two coils and to determine the direction of the current depending on the signals of a magnetic field sensor on the coil arrangement.
Kozarov, A.; Petrov, O.; Antonov, J.; Sotirova, S.; Petrova, B.
2006-01-01
The purpose of the linear wind-power generator described in this article is to decrease the following disadvantages of the common wind-powered turbine: 1) large bending and twisting moments to the blades and the shaft, especially when strong winds and turbulence exist; 2) significant values of the natural oscillation period of the construction result in the possibility of occurrence of destroying resonance oscillations; 3) high velocity of the peripheral parts of the rotor creating a danger for birds; 4) difficulties, connected with the installation and the operation on the mountain ridges and passages where the wind energy potential is the largest. The working surfaces of the generator in questions driven by the wind are not connected with a joint shaft but each moves along a railway track with few oscillations. So the sizes of each component are small and their number can be rather large. The mechanical trajectory is not a circle but a closed outline in a vertical plain, which consists of two rectilinear sectors, one above the other, connected in their ends by semi-circumferences. The mechanical energy of each component turns into electrical on the principle of the linear electrical generator. A regulation is provided when the direction of the wind is perpendicular to the route. A possibility of effectiveness is shown through aiming of additional quantities of air to the movable components by static barriers
Linearization of the Lorenz system
Li, Chunbiao; Sprott, Julien Clinton; Thio, Wesley
2015-01-01
A partial and complete piecewise linearized version of the Lorenz system is proposed. The linearized versions have an independent total amplitude control parameter. Additional further linearization leads naturally to a piecewise linear version of the diffusionless Lorenz system. A chaotic circuit with a single amplitude controller is then implemented using a new switch element, producing a chaotic oscillation that agrees with the numerical calculation for the piecewise linear diffusionless Lorenz system. - Highlights: • A partial and complete piecewise linearized version of the Lorenz system are addressed. • The linearized versions have an independent total amplitude control parameter. • A piecewise linear version of the diffusionless Lorenz system is derived by further linearization. • A corresponding chaotic circuit without any multiplier is implemented for the chaotic oscillation
Topics in computational linear optimization
Hultberg, Tim Helge
2000-01-01
Linear optimization has been an active area of research ever since the pioneering work of G. Dantzig more than 50 years ago. This research has produced a long sequence of practical as well as theoretical improvements of the solution techniques avilable for solving linear optimization problems...... of high quality solvers and the use of algebraic modelling systems to handle the communication between the modeller and the solver. This dissertation features four topics in computational linear optimization: A) automatic reformulation of mixed 0/1 linear programs, B) direct solution of sparse unsymmetric...... systems of linear equations, C) reduction of linear programs and D) integration of algebraic modelling of linear optimization problems in C++. Each of these topics is treated in a separate paper included in this dissertation. The efficiency of solving mixed 0-1 linear programs by linear programming based...
Linearization of the Lorenz system
Li, Chunbiao, E-mail: goontry@126.com [School of Electronic & Information Engineering, Nanjing University of Information Science & Technology, Nanjing 210044 (China); Engineering Technology Research and Development Center of Jiangsu Circulation Modernization Sensor Network, Jiangsu Institute of Commerce, Nanjing 211168 (China); Sprott, Julien Clinton [Department of Physics, University of Wisconsin–Madison, Madison, WI 53706 (United States); Thio, Wesley [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, OH 43210 (United States)
2015-05-08
A partial and complete piecewise linearized version of the Lorenz system is proposed. The linearized versions have an independent total amplitude control parameter. Additional further linearization leads naturally to a piecewise linear version of the diffusionless Lorenz system. A chaotic circuit with a single amplitude controller is then implemented using a new switch element, producing a chaotic oscillation that agrees with the numerical calculation for the piecewise linear diffusionless Lorenz system. - Highlights: • A partial and complete piecewise linearized version of the Lorenz system are addressed. • The linearized versions have an independent total amplitude control parameter. • A piecewise linear version of the diffusionless Lorenz system is derived by further linearization. • A corresponding chaotic circuit without any multiplier is implemented for the chaotic oscillation.
On the linear programming bound for linear Lee codes.
Astola, Helena; Tabus, Ioan
2016-01-01
Based on an invariance-type property of the Lee-compositions of a linear Lee code, additional equality constraints can be introduced to the linear programming problem of linear Lee codes. In this paper, we formulate this property in terms of an action of the multiplicative group of the field [Formula: see text] on the set of Lee-compositions. We show some useful properties of certain sums of Lee-numbers, which are the eigenvalues of the Lee association scheme, appearing in the linear programming problem of linear Lee codes. Using the additional equality constraints, we formulate the linear programming problem of linear Lee codes in a very compact form, leading to a fast execution, which allows to efficiently compute the bounds for large parameter values of the linear codes.
Introduction to linear elasticity
Gould, Phillip L
2013-01-01
Introduction to Linear Elasticity, 3rd Edition, provides an applications-oriented grounding in the tensor-based theory of elasticity for students in mechanical, civil, aeronautical, and biomedical engineering, as well as materials and earth science. The book is distinct from the traditional text aimed at graduate students in solid mechanics by introducing the subject at a level appropriate for advanced undergraduate and beginning graduate students. The author's presentation allows students to apply the basic notions of stress analysis and move on to advanced work in continuum mechanics, plasticity, plate and shell theory, composite materials, viscoelasticity and finite method analysis. This book also: Emphasizes tensor-based approach while still distilling down to explicit notation Provides introduction to theory of plates, theory of shells, wave propagation, viscoelasticity and plasticity accessible to advanced undergraduate students Appropriate for courses following emerging trend of teaching solid mechan...
Haniger, L.; Elger, R.; Kocandrle, L.; Zdebor, J.
1986-01-01
A linear step drive is described developed in Czechoslovak-Soviet cooperation and intended for driving WWER-1000 control rods. The functional principle is explained of the motor and the mechanical and electrical parts of the drive, power control, and the indicator of position are described. The motor has latches situated in the reactor at a distance of 3 m from magnetic armatures, it has a low structural height above the reactor cover, which suggests its suitability for seismic localities. Its magnetic circuits use counterpoles; the mechanical shocks at the completion of each step are damped using special design features. The position indicator is of a special design and evaluates motor position within ±1% of total travel. A drive diagram and the flow chart of both the control electronics and the position indicator are presented. (author) 4 figs
Tjutju, R.L.
1977-01-01
Pulse amplifier is standard significant part of spectrometer. Apart from other type of amplification, it's a combination of amplification and pulse shaping. Because of its special purpose the device should fulfill the following : High resolution is desired to gain a high yield comparable to its actual state of condition. High signal to noise is desired to nhν resolution. High linearity to facilitate calibration. A good overload recovery, in order to the device will capable of analizing a low energy radiation which appear joinly on the high energy fields. Other expections of the device are its economical and practical use its extentive application. For that reason it's built on a standard NIM principle. Taking also into account the above mentioned considerations. High quality component parts are used throughout, while its availability in the domestic market is secured. (author)
1976-01-01
This report covers the activity of the Linear Accelerator Laboratory during the period June 1974-June 1976. The activity of the Laboratory is essentially centered on high energy physics. The main activities were: experiments performed with the colliding rings (ACO), construction of the new colliding rings and beginning of the work at higher energy (DCI), bubble chamber experiments with the CERN PS neutrino beam, counter experiments with CERN's PS and setting-up of equipment for new experiments with CERN's SPS. During this period a project has also been prepared for an experiment with the new PETRA colliding ring at Hamburg. On the other hand, intense collaboration with the LURE Laboratory, using the electron synchrotron radiation emitted by ACO and DCI, has been developed [fr
Van Atta, C.M.; Beringer, R.; Smith, L.
1959-01-01
A linear accelerator of heavy ions is described. The basic contributions of the invention consist of a method and apparatus for obtaining high energy particles of an element with an increased charge-to-mass ratio. The method comprises the steps of ionizing the atoms of an element, accelerating the resultant ions to an energy substantially equal to one Mev per nucleon, stripping orbital electrons from the accelerated ions by passing the ions through a curtain of elemental vapor disposed transversely of the path of the ions to provide a second charge-to-mass ratio, and finally accelerating the resultant stripped ions to a final energy of at least ten Mev per nucleon.
Tip, A.
1998-06-01
Starting from Maxwell's equations for a linear, nonconducting, absorptive, and dispersive medium, characterized by the constitutive equations D(x,t)=ɛ1(x)E(x,t)+∫t-∞dsχ(x,t-s)E(x,s) and H(x,t)=B(x,t), a unitary time evolution and canonical formalism is obtained. Given the complex, coordinate, and frequency-dependent, electric permeability ɛ(x,ω), no further assumptions are made. The procedure leads to a proper definition of band gaps in the periodic case and a new continuity equation for energy flow. An S-matrix formalism for scattering from lossy objects is presented in full detail. A quantized version of the formalism is derived and applied to the generation of Čerenkov and transition radiation as well as atomic decay. The last case suggests a useful generalization of the density of states to the absorptive situation.
Gomes, Guilherme J. C.; Vrugt, Jasper A.; Vargas, Eurípedes A.
2016-04-01
The depth to bedrock controls a myriad of processes by influencing subsurface flow paths, erosion rates, soil moisture, and water uptake by plant roots. As hillslope interiors are very difficult and costly to illuminate and access, the topography of the bedrock surface is largely unknown. This essay is concerned with the prediction of spatial patterns in the depth to bedrock (DTB) using high-resolution topographic data, numerical modeling, and Bayesian analysis. Our DTB model builds on the bottom-up control on fresh-bedrock topography hypothesis of Rempe and Dietrich (2014) and includes a mass movement and bedrock-valley morphology term to extent the usefulness and general applicability of the model. We reconcile the DTB model with field observations using Bayesian analysis with the DREAM algorithm. We investigate explicitly the benefits of using spatially distributed parameter values to account implicitly, and in a relatively simple way, for rock mass heterogeneities that are very difficult, if not impossible, to characterize adequately in the field. We illustrate our method using an artificial data set of bedrock depth observations and then evaluate our DTB model with real-world data collected at the Papagaio river basin in Rio de Janeiro, Brazil. Our results demonstrate that the DTB model predicts accurately the observed bedrock depth data. The posterior mean DTB simulation is shown to be in good agreement with the measured data. The posterior prediction uncertainty of the DTB model can be propagated forward through hydromechanical models to derive probabilistic estimates of factors of safety.
Romano, Nunzio; De Falco, Melania; Speranza, Giuseppe; Tarolli, Paolo
2015-04-01
Mediterranean environments are characterized by a climatic regime with a strong seasonal variability. More uniform precipitations usually occur during the winter season, whereas short and very intense rainfalls occur during the fall and early spring that, in turn, trigger surface runoff and severe soil erosion phenomena. When this typical seasonality interacts with a territory substantially altered by anthropic actions, conditions can easily arise for environmental imbalances with serious risks for flash floods and landslides. Many of the degradation dynamics recorded during the last decades in western countries are also the result of the socio-economic changes after the II world war which yielded land-use changes with the urban sprawl process and the increase in human settlements of the natural environments. We are also witnessing a change in the perception of the natural environment and the relevant values. This study benefits from the availability of historical maps and rainfall time series to analyze the profound landscape changes occurred during the last century along the hillsides of the Somma-Vesuvio volcano, in the renowned piedmont area located at east of Napoli city. We are specifically interested in the changes and disturbances made to the hydrographic network to evaluate the increasing potential risks for flood and landslides along these hillslopes characterized by the presence of highly vulnerable volcanic soils, the construction of roads, and other negative alterations of the natural overland flow patterns.
Wiaux, François; Vanclooster, Marnik; Cornelis, Jean-Thomas; Van Oost, Kristof
2014-05-01
The combination of hydrologic, geomorphic and biogeochemical approaches is required to determine organic carbon (OC) persistence and dynamics within landscapes. Here, we used soil in-situ surface heterotrophic respiration measurement as an indicator of OC persistence along a hillslope (crop field on the loess belt under temperate climate), characterized by an important erosion-induced OC stock colluvium downslope. Along this topographical gradient, we quantified the space-time structure of soil water and temperature, and soil OC amount and quality (from a chemical point of view based on NaOCl oxidation) in relation to CO2 fluxes. We used a Generalized Least Square (GLS) regression model to identify the role of each abiotic factor as well as their interactions on observed soil respiration rates, and to calculate time-average values of these CO2 fluxes at each studied slope positions. We observed significant differences between the observed respiration rates along the topographical gradient (up to 30% more CO2 emissions downslope and 50% backslope, relative to un-eroded summit position). Despite mean CO2 fluxes (standardized at 15°C) at the bottom of the slope are significantly higher (ppedo-climatic ecosystem would be changed.
Renner, Maik; Hassler, Sibylle; Blume, Theresa; Weiler, Markus; Hildebrandt, Anke; Guderle, Marcus; Schymanski, Stan; Kleidon, Axel
2016-04-01
Roberts (1983) found that forest transpiration is relatively uniform across different climatic conditions and suggested that forest transpiration is a conservative process compensating for environmental heterogeneity. Here we test this hypothesis at a steep valley cross-section composed of European Beech in the Attert basin in Luxemburg. We use sapflow, soil moisture, biometric and meteorological data from 6 sites along a transect to estimate site scale transpiration rates. Despite opposing hillslope orientation, different slope angles and forest stand structures, we estimated relatively similar transpiration responses to atmospheric demand and seasonal transpiration totals. This similarity is related to a negative correlation between sap velocity and site-average sapwood area. At the south facing sites with an old, even-aged stand structure and closed canopy layer, we observe significantly lower sap velocities but similar stand-average transpiration rates compared to the north-facing sites with open canopy structure, tall dominant trees and dense understorey. This suggests that plant hydraulic co-ordination allows for flexible responses to environmental conditions leading to similar transpiration rates close to the water and energy limits despite the apparent heterogeneity in exposition, stand density and soil moisture. References Roberts, J. (1983). Forest transpiration: A conservative hydrological process? Journal of Hydrology 66, 133-141.
Computer Program For Linear Algebra
Krogh, F. T.; Hanson, R. J.
1987-01-01
Collection of routines provided for basic vector operations. Basic Linear Algebra Subprogram (BLAS) library is collection from FORTRAN-callable routines for employing standard techniques to perform basic operations of numerical linear algebra.
Quaternion Linear Canonical Transform Application
Bahri, Mawardi
2015-01-01
Quaternion linear canonical transform (QLCT) is a generalization of the classical linear canonical transfom (LCT) using quaternion algebra. The focus of this paper is to introduce an application of the QLCT to study of generalized swept-frequency filter
Recursive Algorithm For Linear Regression
Varanasi, S. V.
1988-01-01
Order of model determined easily. Linear-regression algorithhm includes recursive equations for coefficients of model of increased order. Algorithm eliminates duplicative calculations, facilitates search for minimum order of linear-regression model fitting set of data satisfactory.
Dynamical systems and linear algebra
Colonius, Fritz (Prof.)
2007-01-01
Dynamical systems and linear algebra / F. Colonius, W. Kliemann. - In: Handbook of linear algebra / ed. by Leslie Hogben. - Boca Raton : Chapman & Hall/CRC, 2007. - S. 56,1-56,22. - (Discrete mathematics and its applications)
Linear spaces: history and theory
Albrecht Beutelspracher
1990-01-01
Linear spaces belong to the most fundamental geometric and combinatorial structures. In this paper I would like to give an onerview about the theory of embedding finite linear spaces in finite projective planes.
Linear versus non-linear supersymmetry, in general
Ferrara, Sergio [Theoretical Physics Department, CERN,CH-1211 Geneva 23 (Switzerland); INFN - Laboratori Nazionali di Frascati,Via Enrico Fermi 40, I-00044 Frascati (Italy); Department of Physics and Astronomy, UniversityC.L.A.,Los Angeles, CA 90095-1547 (United States); Kallosh, Renata [SITP and Department of Physics, Stanford University,Stanford, California 94305 (United States); Proeyen, Antoine Van [Institute for Theoretical Physics, Katholieke Universiteit Leuven,Celestijnenlaan 200D, B-3001 Leuven (Belgium); Wrase, Timm [Institute for Theoretical Physics, Technische Universität Wien,Wiedner Hauptstr. 8-10, A-1040 Vienna (Austria)
2016-04-12
We study superconformal and supergravity models with constrained superfields. The underlying version of such models with all unconstrained superfields and linearly realized supersymmetry is presented here, in addition to the physical multiplets there are Lagrange multiplier (LM) superfields. Once the equations of motion for the LM superfields are solved, some of the physical superfields become constrained. The linear supersymmetry of the original models becomes non-linearly realized, its exact form can be deduced from the original linear supersymmetry. Known examples of constrained superfields are shown to require the following LM’s: chiral superfields, linear superfields, general complex superfields, some of them are multiplets with a spin.
Linear versus non-linear supersymmetry, in general
Ferrara, Sergio; Kallosh, Renata; Proeyen, Antoine Van; Wrase, Timm
2016-01-01
We study superconformal and supergravity models with constrained superfields. The underlying version of such models with all unconstrained superfields and linearly realized supersymmetry is presented here, in addition to the physical multiplets there are Lagrange multiplier (LM) superfields. Once the equations of motion for the LM superfields are solved, some of the physical superfields become constrained. The linear supersymmetry of the original models becomes non-linearly realized, its exact form can be deduced from the original linear supersymmetry. Known examples of constrained superfields are shown to require the following LM’s: chiral superfields, linear superfields, general complex superfields, some of them are multiplets with a spin.
Monahan, John F
2008-01-01
Preface Examples of the General Linear Model Introduction One-Sample Problem Simple Linear Regression Multiple Regression One-Way ANOVA First Discussion The Two-Way Nested Model Two-Way Crossed Model Analysis of Covariance Autoregression Discussion The Linear Least Squares Problem The Normal Equations The Geometry of Least Squares Reparameterization Gram-Schmidt Orthonormalization Estimability and Least Squares Estimators Assumptions for the Linear Mean Model Confounding, Identifiability, and Estimability Estimability and Least Squares Estimators F
Templates for Linear Algebra Problems
Bai, Z.; Day, D.; Demmel, J.; Dongarra, J.; Gu, M.; Ruhe, A.; Vorst, H.A. van der
1995-01-01
The increasing availability of advanced-architecture computers is having a very signicant eect on all spheres of scientic computation, including algorithm research and software development in numerical linear algebra. Linear algebra {in particular, the solution of linear systems of equations and
Linearization of CIF through SOS
Nadales Agut, D.E.; Reniers, M.A.; Luttik, B.; Valencia, F.
2011-01-01
Linearization is the procedure of rewriting a process term into a linear form, which consist only of basic operators of the process language. This procedure is interesting both from a theoretical and a practical point of view. In particular, a linearization algorithm is needed for the Compositional
Engberg, Uffe Henrik; Winskel, Glynn
This article shows how individual Petri nets form models of Girard's intuitionistic linear logic. It explores questions of expressiveness and completeness of linear logic with respect to this interpretation. An aim is to use Petri nets to give an understanding of linear logic and give some apprai...
Richards, J.A.
1977-01-01
A linear particle accelerator which provides a pulsed beam of charged particles of uniform energy is described. The accelerator is in the form of an evacuated dielectric tube, inside of which a particle source is located at one end of the tube, with a target or window located at the other end of the dielectric tube. Along the length of the tube are externally located pairs of metal plates, each insulated from each other in an insulated housing. Each of the plates of a pair are connected to an electrical source of voltage of opposed polarity, with the polarity of the voltage of the plates oriented so that the plate of a pair, nearer to the particle source, is of the opposed polarity to the charge of the particle emitted by the source. Thus, a first plate about the tube located nearest the particle source, attracts a particle which as it passes through the tube past the first plate is then repelled by the reverse polarity of the second plate of the pair to continue moving towards the target
Generalized Linear Covariance Analysis
Carpenter, James R.; Markley, F. Landis
2014-01-01
This talk presents a comprehensive approach to filter modeling for generalized covariance analysis of both batch least-squares and sequential estimators. We review and extend in two directions the results of prior work that allowed for partitioning of the state space into solve-for'' and consider'' parameters, accounted for differences between the formal values and the true values of the measurement noise, process noise, and textita priori solve-for and consider covariances, and explicitly partitioned the errors into subspaces containing only the influence of the measurement noise, process noise, and solve-for and consider covariances. In this work, we explicitly add sensitivity analysis to this prior work, and relax an implicit assumption that the batch estimator's epoch time occurs prior to the definitive span. We also apply the method to an integrated orbit and attitude problem, in which gyro and accelerometer errors, though not estimated, influence the orbit determination performance. We illustrate our results using two graphical presentations, which we call the variance sandpile'' and the sensitivity mosaic,'' and we compare the linear covariance results to confidence intervals associated with ensemble statistics from a Monte Carlo analysis.
Equipartitioning in linear accelerators
Jameson, R.A.
1982-01-01
Emittance growth has long been a concern in linear accelerators, as has the idea that some kind of energy balance, or equipartitioning, between the degrees of freedom, would ameliorate the growth. M. Prome observed that the average transverse and longitudinal velocity spreads tend to equalize as current in the channel is increased, while the sum of the energy in the system stays nearly constant. However, only recently have we shown that an equipartitioning requirement on a bunched injected beam can indeed produce remarkably small emittance growth. The simple set of equations leading to this condition are outlined. At the same time, Hofmann has investigated collective instabilities in transported beams and has identified thresholds and regions in parameter space where instabilities occur. Evidence is presented that shows transport system boundaries to be quite accurate in computer simulations of accelerating systems. Discussed are preliminary results of efforts to design accelerators that avoid parameter regions where emittance is affected by the instabilities identified by Hofmann. These efforts suggest that other mechanisms are present. The complicated behavior of the RFQ linac in this framework also is shown
Equipartitioning in linear accelerators
Jameson, R.A.
1981-01-01
Emittance growth has long been a concern in linear accelerators, as has the idea that some kind of energy balance, or equipartitioning, between the degrees of freedom, would ameliorate the growth. M. Prome observed that the average transverse and longitudinal velocity spreads tend to equalize as current in the channel is increased, while the sum of the energy in the system stays nearly constant. However, only recently have we shown that an equipartitioning requirement on a bunched injected beam can indeed produce remarkably small emittance growth. The simple set of equations leading to this condition are outlined below. At the same time, Hofmann, using powerful analytical and computational methods, has investigated collective instabilities in transported beams and has identified thresholds and regions in parameter space where instabilities occur. This is an important generalization. Work that he will present at this conference shows that the results are essentially the same in r-z coordinates for transport systems, and evidence is presented that shows transport system boundaries to be quite accurate in computer simulations of accelerating systems also. Discussed are preliminary results of efforts to design accelerators that avoid parameter regions where emittance is affected by the instabilities identified by Hofmann. These efforts suggest that other mechanisms are present. The complicated behavior of the RFQ linac in this framework also is shown
Briggs, R.J.
1986-06-01
The development of linear induction accelerators has been motivated by applications requiring high-pulsed currents of charged particles at voltages exceeding the capability of single-stage, diode-type accelerators and at currents too high for rf accelerators. In principle, one can accelerate charged particles to arbitrarily high voltages using a multi-stage induction machine, but the 50-MeV, 10-kA Advanced Test Accelerator (ATA) at LLNL is the highest voltage machine in existence at this time. The advent of magnetic pulse power systems makes sustained operation at high-repetition rates practical, and this capability for high-average power is very likely to open up many new applications of induction machines in the future. This paper surveys the US induction linac technology with primary emphasis on electron machines. A simplified description of how induction machines couple energy to the electron beam is given, to illustrate many of the general issues that bound the design space of induction linacs
Berkeley Proton Linear Accelerator
Alvarez, L. W.; Bradner, H.; Franck, J.; Gordon, H.; Gow, J. D.; Marshall, L. C.; Oppenheimer, F. F.; Panofsky, W. K. H.; Richman, C.; Woodyard, J. R.
1953-10-13
A linear accelerator, which increases the energy of protons from a 4 Mev Van de Graaff injector, to a final energy of 31.5 Mev, has been constructed. The accelerator consists of a cavity 40 feet long and 39 inches in diameter, excited at resonance in a longitudinal electric mode with a radio-frequency power of about 2.2 x 10{sup 6} watts peak at 202.5 mc. Acceleration is made possible by the introduction of 46 axial "drift tubes" into the cavity, which is designed such that the particles traverse the distance between the centers of successive tubes in one cycle of the r.f. power. The protons are longitudinally stable as in the synchrotron, and are stabilized transversely by the action of converging fields produced by focusing grids. The electrical cavity is constructed like an inverted airplane fuselage and is supported in a vacuum tank. Power is supplied by 9 high powered oscillators fed from a pulse generator of the artificial transmission line type.
Random linear codes in steganography
Kamil Kaczyński
2016-12-01
Full Text Available Syndrome coding using linear codes is a technique that allows improvement in the steganographic algorithms parameters. The use of random linear codes gives a great flexibility in choosing the parameters of the linear code. In parallel, it offers easy generation of parity check matrix. In this paper, the modification of LSB algorithm is presented. A random linear code [8, 2] was used as a base for algorithm modification. The implementation of the proposed algorithm, along with practical evaluation of algorithms’ parameters based on the test images was made.[b]Keywords:[/b] steganography, random linear codes, RLC, LSB
Linear Algebraic Method for Non-Linear Map Analysis
Yu, L.; Nash, B.
2009-01-01
We present a newly developed method to analyze some non-linear dynamics problems such as the Henon map using a matrix analysis method from linear algebra. Choosing the Henon map as an example, we analyze the spectral structure, the tune-amplitude dependence, the variation of tune and amplitude during the particle motion, etc., using the method of Jordan decomposition which is widely used in conventional linear algebra.
Livia Arantes Camargo
2010-06-01
Full Text Available The influence of relief forms has been studied by several authors and explains the variability in the soil attributes of a landscape. Soil physical attributes depend on relief forms, and their assessment is important in mechanized agricultural systems, such as of sugarcane. This study aimed to characterize the spatial variability in the physical soil attributes and their relationship to the hillslope curvatures in an Alfisol developed from sandstone and growing sugarcane. Grids of 100 x 100 m were delimited in a convex and a concave area. The grids had a regular spacing of 10 x 10 m, and the crossing points of this spacing determined a total of 121 georeferenced sampling points. Samples were collected to determine the physical attributes related to soil aggregates, porosity, bulk density, resistance to penetration and moisture within the 0-0.2 and 0.2-0.4 m depth. Statistical analyses, geostatistics and Student's t-tests were performed with the means of the areas. All attributes, except aggregates > 2 mm in the 0-0.2 m depth and macroporosity at both depths, showed significant differences between the hillslope curvatures. The convex area showed the highest values of the mean weighted diameter, mean geometric diameter, aggregates > 2 mm, 1-2 mm aggregates, total porosity and moisture and lower values of bulk density and resistance to penetration in both depth compared to the concave area. The number of soil attributes with greater spatial variability was higher in the concave area.A influência das formas do relevo tem sido estudada por diversos autores e explica a variabilidade dos atributos do solo na paisagem. Os atributos físicos do solo são dependentes das formas do relevo, e a avaliação desses atributos é importante em sistemas mecanizados como o da cultura de cana-de-açúcar. O presente estudo teve como objetivo caracterizar a variabilidade espacial dos atributos físicos de Argissolos desenvolvidos de arenito e cultivados com cana
Volkmann, T. H. M.; Sengupta, A.; Pangle, L.; Abramson, N.; Barron-Gafford, G.; Breshears, D. D.; Bugaj, A.; Chorover, J.; Dontsova, K.; Durcik, M.; Ferre, T. P. A.; Harman, C. J.; Hunt, E.; Huxman, T. E.; Kim, M.; Maier, R. M.; Matos, K.; Alves Meira Neto, A.; Meredith, L. K.; Monson, R. K.; Niu, G. Y.; Pelletier, J. D.; Rasmussen, C.; Ruiz, J.; Saleska, S. R.; Schaap, M. G.; Sibayan, M.; Tuller, M.; Van Haren, J. L. M.; Wang, Y.; Zeng, X.; Troch, P. A.
2017-12-01
Understanding the process interactions and feedbacks among water, microbes, plants, and porous geological media is crucial for improving predictions of the response of Earth's critical zone to future climatic conditions. However, the integrated co-evolution of landscapes under change is notoriously difficult to investigate. Laboratory studies are typically limited in spatial and temporal scale, while field studies lack observational density and control. To bridge the gap between controlled lab and uncontrolled field studies, the University of Arizona - Biosphere 2 built a macrocosm experiment of unprecedented scale: the Landscape Evolution Observatory (LEO). LEO consists of three replicated, 330-m2 hillslope landscapes inside a 5000-m2 environmentally controlled facility. The engineered landscapes contain 1-m depth of basaltic tephra ground to homogenous loamy sand that will undergo physical, chemical, and mineralogical changes over many years. Each landscape contains a dense sensor network capable of resolving water, carbon, and energy cycling processes at sub-meter to whole-landscape scale. Embedded sampling devices allow for quantification of biogeochemical processes, and facilitate the use of chemical tracers applied with the artificial rainfall. LEO is now fully operational and intensive forcing experiments have been launched. While operating the massive infrastructure poses significant challenges, LEO has demonstrated the capacity of tracking multi-scale matter and energy fluxes at a level of detail impossible in field experiments. Initial sensor, sampler, and restricted soil coring data are already providing insights into the tight linkages between water flow, weathering, and (micro-) biological community development during incipient landscape evolution. Over the years to come, these interacting processes are anticipated to drive the model systems to increasingly complex states, potentially perturbed by changes in climatic forcing. By intensively monitoring
Linear Programming and Network Flows
Bazaraa, Mokhtar S; Sherali, Hanif D
2011-01-01
The authoritative guide to modeling and solving complex problems with linear programming-extensively revised, expanded, and updated The only book to treat both linear programming techniques and network flows under one cover, Linear Programming and Network Flows, Fourth Edition has been completely updated with the latest developments on the topic. This new edition continues to successfully emphasize modeling concepts, the design and analysis of algorithms, and implementation strategies for problems in a variety of fields, including industrial engineering, management science, operations research
LINEAR2007, Linear-Linear Interpolation of ENDF Format Cross-Sections
2007-01-01
1 - Description of program or function: LINEAR converts evaluated cross sections in the ENDF/B format into a tabular form that is subject to linear-linear interpolation in energy and cross section. The code also thins tables of cross sections already in that form. Codes used subsequently need thus to consider only linear-linear data. IAEA1311/15: This version include the updates up to January 30, 2007. Changes in ENDF/B-VII Format and procedures, as well as the evaluations themselves, make it impossible for versions of the ENDF/B pre-processing codes earlier than PREPRO 2007 (2007 Version) to accurately process current ENDF/B-VII evaluations. The present code can handle all existing ENDF/B-VI evaluations through release 8, which will be the last release of ENDF/B-VI. Modifications from previous versions: - Linear VERS. 2007-1 (JAN. 2007): checked against all ENDF/B-VII; increased page size from 60,000 to 600,000 points 2 - Method of solution: Each section of data is considered separately. Each section of File 3, 23, and 27 data consists of a table of cross section versus energy with any of five interpolation laws. LINEAR will replace each section with a new table of energy versus cross section data in which the interpolation law is always linear in energy and cross section. The histogram (constant cross section between two energies) interpolation law is converted to linear-linear by substituting two points for each initial point. The linear-linear is not altered. For the log-linear, linear-log and log- log laws, the cross section data are converted to linear by an interval halving algorithm. Each interval is divided in half until the value at the middle of the interval can be approximated by linear-linear interpolation to within a given accuracy. The LINEAR program uses a multipoint fractional error thinning algorithm to minimize the size of each cross section table
Elementary linear programming with applications
Kolman, Bernard
1995-01-01
Linear programming finds the least expensive way to meet given needs with available resources. Its results are used in every area of engineering and commerce: agriculture, oil refining, banking, and air transport. Authors Kolman and Beck present the basic notions of linear programming and illustrate how they are used to solve important common problems. The software on the included disk leads students step-by-step through the calculations. The Second Edition is completely revised and provides additional review material on linear algebra as well as complete coverage of elementary linear program
Hood, John Linsley
2013-01-01
The Art of Linear Electronics presents the principal aspects of linear electronics and techniques in linear electronic circuit design. The book provides a wide range of information on the elucidation of the methods and techniques in the design of linear electronic circuits. The text discusses such topics as electronic component symbols and circuit drawing; passive and active semiconductor components; DC and low frequency amplifiers; and the basic effects of feedback. Subjects on frequency response modifying circuits and filters; audio amplifiers; low frequency oscillators and waveform generato
Linearity and Non-linearity of Photorefractive effect in Materials ...
Linearity and Non-linearity of Photorefractive effect in Materials using the Band transport ... For low light beam intensities the change in the refractive index is ... field is spatially phase shifted by /2 relative to the interference fringe pattern, which ...
The linear programming bound for binary linear codes
Brouwer, A.E.
1993-01-01
Combining Delsarte's (1973) linear programming bound with the information that certain weights cannot occur, new upper bounds for dmin (n,k), the maximum possible minimum distance of a binary linear code with given word length n and dimension k, are derived.
Linear operator inequalities for strongly stable weakly regular linear systems
Curtain, RF
2001-01-01
We consider the question of the existence of solutions to certain linear operator inequalities (Lur'e equations) for strongly stable, weakly regular linear systems with generating operators A, B, C, 0. These operator inequalities are related to the spectral factorization of an associated Popov
Linear and non-linear optics of condensed matter
McLean, T.P.
1977-01-01
Part I - Linear optics: 1. General introduction. 2. Frequency dependence of epsilon(ω, k vector). 3. Wave-vector dependence of epsilon(ω, k vector). 4. Tensor character of epsilon(ω, k vector). Part II - Non-linear optics: 5. Introduction. 6. A classical theory of non-linear response in one dimension. 7. The generalization to three dimensions. 8. General properties of the polarizability tensors. 9. The phase-matching condition. 10. Propagation in a non-linear dielectric. 11. Second harmonic generation. 12. Coupling of three waves. 13. Materials and their non-linearities. 14. Processes involving energy exchange with the medium. 15. Two-photon absorption. 16. Stimulated Raman effect. 17. Electro-optic effects. 18. Limitations of the approach presented here. (author)
Advanced statistics: linear regression, part I: simple linear regression.
Marill, Keith A
2004-01-01
Simple linear regression is a mathematical technique used to model the relationship between a single independent predictor variable and a single dependent outcome variable. In this, the first of a two-part series exploring concepts in linear regression analysis, the four fundamental assumptions and the mechanics of simple linear regression are reviewed. The most common technique used to derive the regression line, the method of least squares, is described. The reader will be acquainted with other important concepts in simple linear regression, including: variable transformations, dummy variables, relationship to inference testing, and leverage. Simplified clinical examples with small datasets and graphic models are used to illustrate the points. This will provide a foundation for the second article in this series: a discussion of multiple linear regression, in which there are multiple predictor variables.
Crasmareanu Mircea
2017-12-01
Full Text Available We consider the paracomplex version of the notion of mixed linear spaces introduced by M. Jurchescu in [4] by replacing the complex unit i with the paracomplex unit j, j2 = 1. The linear algebra of these spaces is studied with a special view towards their morphisms.
Linear Algebra and Image Processing
Allali, Mohamed
2010-01-01
We use the computing technology digital image processing (DIP) to enhance the teaching of linear algebra so as to make the course more visual and interesting. Certainly, this visual approach by using technology to link linear algebra to DIP is interesting and unexpected to both students as well as many faculty. (Contains 2 tables and 11 figures.)
Efficient Searching with Linear Constraints
Agarwal, Pankaj K.; Arge, Lars Allan; Erickson, Jeff
2000-01-01
We show how to preprocess a set S of points in d into an external memory data structure that efficiently supports linear-constraint queries. Each query is in the form of a linear constraint xd a0+∑d−1i=1 aixi; the data structure must report all the points of S that satisfy the constraint. This pr...
Johnson, Bruce G.; Gerver, Michael J.; Hawkey, Timothy J.; Fenn, Ralph C.
1993-01-01
Improved linear actuator comprises air slide and linear electric motor. Unit exhibits low friction, low backlash, and more nearly even acceleration. Used in machinery in which positions, velocities, and accelerations must be carefully controlled and/or vibrations must be suppressed.
Linear morphoea follows Blaschko's lines.
Weibel, L; Harper, J I
2008-07-01
The aetiology of morphoea (or localized scleroderma) remains unknown. It has previously been suggested that lesions of linear morphoea may follow Blaschko's lines and thus reflect an embryological development. However, the distribution of linear morphoea has never been accurately evaluated. We aimed to identify common patterns of clinical presentation in children with linear morphoea and to establish whether linear morphoea follows the lines of Blaschko. A retrospective chart review of 65 children with linear morphoea was performed. According to clinical photographs the skin lesions of these patients were plotted on to standardized head and body charts. With the aid of Adobe Illustrator a final figure was produced including an overlay of all individual lesions which was used for comparison with the published lines of Blaschko. Thirty-four (53%) patients had the en coup de sabre subtype, 27 (41%) presented with linear morphoea on the trunk and/or limbs and four (6%) children had a combination of the two. In 55 (85%) children the skin lesions were confined to one side of the body, showing no preference for either left or right side. On comparing the overlays of all body and head lesions with the original lines of Blaschko there was an excellent correlation. Our data indicate that linear morphoea follows the lines of Blaschko. We hypothesize that in patients with linear morphoea susceptible cells are present in a mosaic state and that exposure to some trigger factor may result in the development of this condition.
Campagnoli, Patrizia; Petris, Giovanni
2009-01-01
State space models have gained tremendous popularity in as disparate fields as engineering, economics, genetics and ecology. Introducing general state space models, this book focuses on dynamic linear models, emphasizing their Bayesian analysis. It illustrates the fundamental steps needed to use dynamic linear models in practice, using R package.
Linear Programming across the Curriculum
Yoder, S. Elizabeth; Kurz, M. Elizabeth
2015-01-01
Linear programming (LP) is taught in different departments across college campuses with engineering and management curricula. Modeling an LP problem is taught in every linear programming class. As faculty teaching in Engineering and Management departments, the depth to which teachers should expect students to master this particular type of…
Introduction to RF linear accelerators
Weiss, M.
1994-01-01
The basic features of RF linear accelerators are described. The concept of the 'loaded cavity', essential for the synchronism wave-particle, is introduced, and formulae describing the action of electromagnetic fields on the beam are given. The treatment of intense beams is mentioned, and various existing linear accelerators are presented as examples. (orig.)
Spatial Processes in Linear Ordering
von Hecker, Ulrich; Klauer, Karl Christoph; Wolf, Lukas; Fazilat-Pour, Masoud
2016-01-01
Memory performance in linear order reasoning tasks (A > B, B > C, C > D, etc.) shows quicker, and more accurate responses to queries on wider (AD) than narrower (AB) pairs on a hypothetical linear mental model (A -- B -- C -- D). While indicative of an analogue representation, research so far did not provide positive evidence for spatial…
Andersen, O. Krogh
1975-01-01
of Korringa-Kohn-Rostoker, linear-combination-of-atomic-orbitals, and cellular methods; the secular matrix is linear in energy, the overlap integrals factorize as potential parameters and structure constants, the latter are canonical in the sense that they neither depend on the energy nor the cell volume...
Introduction to generalized linear models
Dobson, Annette J
2008-01-01
Introduction Background Scope Notation Distributions Related to the Normal Distribution Quadratic Forms Estimation Model Fitting Introduction Examples Some Principles of Statistical Modeling Notation and Coding for Explanatory Variables Exponential Family and Generalized Linear Models Introduction Exponential Family of Distributions Properties of Distributions in the Exponential Family Generalized Linear Models Examples Estimation Introduction Example: Failure Times for Pressure Vessels Maximum Likelihood Estimation Poisson Regression Example Inference Introduction Sampling Distribution for Score Statistics Taylor Series Approximations Sampling Distribution for MLEs Log-Likelihood Ratio Statistic Sampling Distribution for the Deviance Hypothesis Testing Normal Linear Models Introduction Basic Results Multiple Linear Regression Analysis of Variance Analysis of Covariance General Linear Models Binary Variables and Logistic Regression Probability Distributions ...
Acoustic emission linear pulse holography
Collins, H.D.; Busse, L.J.; Lemon, D.K.
1983-01-01
This paper describes the emission linear pulse holography which produces a chronological linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. A thirty two point sampling array is used to construct phase-only linear holograms of simulated acoustic emission sources on large metal plates. The concept behind the AE linear pulse holography is illustrated, and a block diagram of a data acquisition system to implement the concept is given. Array element spacing, synthetic frequency criteria, and lateral depth resolution are specified. A reference timing transducer positioned between the array and the inspection zone and which inititates the time-of-flight measurements is described. The results graphically illustrate the technique using a one-dimensional FFT computer algorithm (ie. linear backward wave) for an AE image reconstruction
Linear and Generalized Linear Mixed Models and Their Applications
Jiang, Jiming
2007-01-01
This book covers two major classes of mixed effects models, linear mixed models and generalized linear mixed models, and it presents an up-to-date account of theory and methods in analysis of these models as well as their applications in various fields. The book offers a systematic approach to inference about non-Gaussian linear mixed models. Furthermore, it has included recently developed methods, such as mixed model diagnostics, mixed model selection, and jackknife method in the context of mixed models. The book is aimed at students, researchers and other practitioners who are interested
Ferencz, Donald C.; Viterna, Larry A.
1991-01-01
ALPS is a computer program which can be used to solve general linear program (optimization) problems. ALPS was designed for those who have minimal linear programming (LP) knowledge and features a menu-driven scheme to guide the user through the process of creating and solving LP formulations. Once created, the problems can be edited and stored in standard DOS ASCII files to provide portability to various word processors or even other linear programming packages. Unlike many math-oriented LP solvers, ALPS contains an LP parser that reads through the LP formulation and reports several types of errors to the user. ALPS provides a large amount of solution data which is often useful in problem solving. In addition to pure linear programs, ALPS can solve for integer, mixed integer, and binary type problems. Pure linear programs are solved with the revised simplex method. Integer or mixed integer programs are solved initially with the revised simplex, and the completed using the branch-and-bound technique. Binary programs are solved with the method of implicit enumeration. This manual describes how to use ALPS to create, edit, and solve linear programming problems. Instructions for installing ALPS on a PC compatible computer are included in the appendices along with a general introduction to linear programming. A programmers guide is also included for assistance in modifying and maintaining the program.
Linear and quasi-linear equations of parabolic type
Ladyženskaja, O A; Ural′ceva, N N; Uralceva, N N
1968-01-01
Equations of parabolic type are encountered in many areas of mathematics and mathematical physics, and those encountered most frequently are linear and quasi-linear parabolic equations of the second order. In this volume, boundary value problems for such equations are studied from two points of view: solvability, unique or otherwise, and the effect of smoothness properties of the functions entering the initial and boundary conditions on the smoothness of the solutions.
The Theory of Linear Prediction
Vaidyanathan, PP
2007-01-01
Linear prediction theory has had a profound impact in the field of digital signal processing. Although the theory dates back to the early 1940s, its influence can still be seen in applications today. The theory is based on very elegant mathematics and leads to many beautiful insights into statistical signal processing. Although prediction is only a part of the more general topics of linear estimation, filtering, and smoothing, this book focuses on linear prediction. This has enabled detailed discussion of a number of issues that are normally not found in texts. For example, the theory of vecto
Correlation and simple linear regression.
Zou, Kelly H; Tuncali, Kemal; Silverman, Stuart G
2003-06-01
In this tutorial article, the concepts of correlation and regression are reviewed and demonstrated. The authors review and compare two correlation coefficients, the Pearson correlation coefficient and the Spearman rho, for measuring linear and nonlinear relationships between two continuous variables. In the case of measuring the linear relationship between a predictor and an outcome variable, simple linear regression analysis is conducted. These statistical concepts are illustrated by using a data set from published literature to assess a computed tomography-guided interventional technique. These statistical methods are important for exploring the relationships between variables and can be applied to many radiologic studies.
Saravanan, R
2018-01-01
Non-linear optical materials have widespread and promising applications, but the efforts to understand the local structure, electron density distribution and bonding is still lacking. The present work explores the structural details, the electron density distribution and the local bond length distribution of some non-linear optical materials. It also gives estimation of the optical band gap, the particle size, crystallite size, and the elemental composition from UV-Visible analysis, SEM, XRD and EDS of some non-linear optical materials respectively.
Optimal control linear quadratic methods
Anderson, Brian D O
2007-01-01
This augmented edition of a respected text teaches the reader how to use linear quadratic Gaussian methods effectively for the design of control systems. It explores linear optimal control theory from an engineering viewpoint, with step-by-step explanations that show clearly how to make practical use of the material.The three-part treatment begins with the basic theory of the linear regulator/tracker for time-invariant and time-varying systems. The Hamilton-Jacobi equation is introduced using the Principle of Optimality, and the infinite-time problem is considered. The second part outlines the
King Cove, Alaska Coastal Digital Elevation Model
National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...
Arena Cove, California Coastal Digital Elevation Model
National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...
Cellular Automata Rules and Linear Numbers
Nayak, Birendra Kumar; Sahoo, Sudhakar; Biswal, Sagarika
2012-01-01
In this paper, linear Cellular Automta (CA) rules are recursively generated using a binary tree rooted at "0". Some mathematical results on linear as well as non-linear CA rules are derived. Integers associated with linear CA rules are defined as linear numbers and the properties of these linear numbers are studied.
Feedback systems for linear colliders
Hendrickson, L; Himel, Thomas M; Minty, Michiko G; Phinney, N; Raimondi, Pantaleo; Raubenheimer, T O; Shoaee, H; Tenenbaum, P G
1999-01-01
Feedback systems are essential for stable operation of a linear collider, providing a cost-effective method for relaxing tight tolerances. In the Stanford Linear Collider (SLC), feedback controls beam parameters such as trajectory, energy, and intensity throughout the accelerator. A novel dithering optimization system which adjusts final focus parameters to maximize luminosity contributed to achieving record performance in the 1997-98 run. Performance limitations of the steering feedback have been investigated, and improvements have been made. For the Next Linear Collider (NLC), extensive feedback systems are planned as an intregal part of the design. Feedback requiremetns for JLC (the Japanese Linear Collider) are essentially identical to NLC; some of the TESLA requirements are similar but there are significant differences. For NLC, algorithms which incorporate improvements upon the SLC implementation are being prototyped. Specialized systems for the damping rings, rf and interaction point will operate at hi...
An introduction to linear algebra
Mirsky, L
2003-01-01
Rigorous, self-contained coverage of determinants, vectors, matrices and linear equations, quadratic forms, more. Elementary, easily readable account with numerous examples and problems at the end of each chapter.
CLIC: developing a linear collider
Laurent Guiraud
1999-01-01
Compact Linear Collider (CLIC) is a CERN project to provide high-energy electron-positron collisions. Instead of conventional radio-frequency klystrons, CLIC will use a low-energy, high-intensity primary beam to produce acceleration.
1988 linear accelerator conference proceedings
1989-06-01
This report contains papers presented at the 1988 Linear Accelerator Conference. A few topics covered are beam dynamics; beam transport; superconducting components; free electron lasers; ion sources; and klystron research
CERN balances linear collider studies
ILC Newsline
2011-01-01
The forces behind the two most mature proposals for a next-generation collider, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC) study, have been steadily coming together, with scientists from both communities sharing ideas and information across the technology divide. In a support of cooperation between the two, CERN in Switzerland, where most CLIC research takes place, recently converted the project-specific position of CLIC Study Leader to the concept-based Linear Collider Study Leader. The scientist who now holds this position, Steinar Stapnes, is charged with making the linear collider a viable option for CERN’s future, one that could include either CLIC or the ILC. The transition to more involve the ILC must be gradual, he said, and the redefinition of his post is a good start. Though not very much involved with superconducting radiofrequency (SRF) technology, where ILC researchers have made significant advances, CERN participates in many aspect...
Linear Methods for Image Interpolation
Pascal Getreuer
2011-01-01
We discuss linear methods for interpolation, including nearest neighbor, bilinear, bicubic, splines, and sinc interpolation. We focus on separable interpolation, so most of what is said applies to one-dimensional interpolation as well as N-dimensional separable interpolation.
Klumpp, A. R.; Lawson, C. L.
1988-01-01
Routines provided for common scalar, vector, matrix, and quaternion operations. Computer program extends Ada programming language to include linear-algebra capabilities similar to HAS/S programming language. Designed for such avionics applications as software for Space Station.
Acoustic emission linear pulse holography
Collins, H.D.; Busse, L.J.; Lemon, D.K.
1983-10-25
This device relates to the concept of and means for performing Acoustic Emission Linear Pulse Holography, which combines the advantages of linear holographic imaging and Acoustic Emission into a single non-destructive inspection system. This unique system produces a chronological, linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. The innovation is the concept of utilizing the crack-generated acoustic emission energy to generate a chronological series of images of a growing crack by applying linear, pulse holographic processing to the acoustic emission data. The process is implemented by placing on a structure an array of piezoelectric sensors (typically 16 or 32 of them) near the defect location. A reference sensor is placed between the defect and the array.
Functionalized linear and cyclic polyolefins
Tuba, Robert; Grubbs, Robert H.
2018-02-13
This invention relates to methods and compositions for preparing linear and cyclic polyolefins. More particularly, the invention relates to methods and compositions for preparing functionalized linear and cyclic polyolefins via olefin metathesis reactions. Polymer products produced via the olefin metathesis reactions of the invention may be utilized for a wide range of materials applications. The invention has utility in the fields of polymer and materials chemistry and manufacture.
Rumen Daskalov
2017-07-01
Full Text Available Let an $[n,k,d]_q$ code be a linear code of length $n$, dimension $k$ and minimum Hamming distance $d$ over $GF(q$. One of the most important problems in coding theory is to construct codes with optimal minimum distances. In this paper 22 new ternary linear codes are presented. Two of them are optimal. All new codes improve the respective lower bounds in [11].
Explorative methods in linear models
Høskuldsson, Agnar
2004-01-01
The author has developed the H-method of mathematical modeling that builds up the model by parts, where each part is optimized with respect to prediction. Besides providing with better predictions than traditional methods, these methods provide with graphic procedures for analyzing different feat...... features in data. These graphic methods extend the well-known methods and results of Principal Component Analysis to any linear model. Here the graphic procedures are applied to linear regression and Ridge Regression....
Polarized Electrons for Linear Colliders
Clendenin, J.
2004-01-01
Future electron-positron linear colliders require a highly polarized electron beam with a pulse structure that depends primarily on whether the acceleration utilizes warm or superconducting rf structures. The International Linear Collider (ILC) will use cold structures for the main linac. It is shown that a dc-biased polarized photoelectron source such as successfully used for the SLC can meet the charge requirements for the ILC micropulse with a polarization approaching 90%
Primordial black holes in linear and non-linear regimes
Allahyari, Alireza; Abolhasani, Ali Akbar [Department of Physics, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Firouzjaee, Javad T., E-mail: allahyari@physics.sharif.edu, E-mail: j.taghizadeh.f@ipm.ir [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)
2017-06-01
We revisit the formation of primordial black holes (PBHs) in the radiation-dominated era for both linear and non-linear regimes, elaborating on the concept of an apparent horizon. Contrary to the expectation from vacuum models, we argue that in a cosmological setting a density fluctuation with a high density does not always collapse to a black hole. To this end, we first elaborate on the perturbation theory for spherically symmetric space times in the linear regime. Thereby, we introduce two gauges. This allows to introduce a well defined gauge-invariant quantity for the expansion of null geodesics. Using this quantity, we argue that PBHs do not form in the linear regime irrespective of the density of the background. Finally, we consider the formation of PBHs in non-linear regimes, adopting the spherical collapse picture. In this picture, over-densities are modeled by closed FRW models in the radiation-dominated era. The difference of our approach is that we start by finding an exact solution for a closed radiation-dominated universe. This yields exact results for turn-around time and radius. It is important that we take the initial conditions from the linear perturbation theory. Additionally, instead of using uniform Hubble gauge condition, both density and velocity perturbations are admitted in this approach. Thereby, the matching condition will impose an important constraint on the initial velocity perturbations δ {sup h} {sub 0} = −δ{sub 0}/2. This can be extended to higher orders. Using this constraint, we find that the apparent horizon of a PBH forms when δ > 3 at turn-around time. The corrections also appear from the third order. Moreover, a PBH forms when its apparent horizon is outside the sound horizon at the re-entry time. Applying this condition, we infer that the threshold value of the density perturbations at horizon re-entry should be larger than δ {sub th} > 0.7.
The linear-non-linear frontier for the Goldstone Higgs
Gavela, M.B.; Saa, S.; Kanshin, K.; Machado, P.A.N.
2016-01-01
The minimal SO(5)/SO(4) σ-model is used as a template for the ultraviolet completion of scenarios in which the Higgs particle is a low-energy remnant of some high-energy dynamics, enjoying a (pseudo) Nambu-Goldstone-boson ancestry. Varying the σ mass allows one to sweep from the perturbative regime to the customary non-linear implementations. The low-energy benchmark effective non-linear Lagrangian for bosons and fermions is obtained, determining as well the operator coefficients including linear corrections. At first order in the latter, three effective bosonic operators emerge which are independent of the explicit soft breaking assumed. The Higgs couplings to vector bosons and fermions turn out to be quite universal: the linear corrections are proportional to the explicit symmetry-breaking parameters. Furthermore, we define an effective Yukawa operator which allows a simple parametrization and comparison of different heavy-fermion ultraviolet completions. In addition, one particular fermionic completion is explored in detail, obtaining the corresponding leading low-energy fermionic operators. (orig.)
Advanced statistics: linear regression, part II: multiple linear regression.
Marill, Keith A
2004-01-01
The applications of simple linear regression in medical research are limited, because in most situations, there are multiple relevant predictor variables. Univariate statistical techniques such as simple linear regression use a single predictor variable, and they often may be mathematically correct but clinically misleading. Multiple linear regression is a mathematical technique used to model the relationship between multiple independent predictor variables and a single dependent outcome variable. It is used in medical research to model observational data, as well as in diagnostic and therapeutic studies in which the outcome is dependent on more than one factor. Although the technique generally is limited to data that can be expressed with a linear function, it benefits from a well-developed mathematical framework that yields unique solutions and exact confidence intervals for regression coefficients. Building on Part I of this series, this article acquaints the reader with some of the important concepts in multiple regression analysis. These include multicollinearity, interaction effects, and an expansion of the discussion of inference testing, leverage, and variable transformations to multivariate models. Examples from the first article in this series are expanded on using a primarily graphic, rather than mathematical, approach. The importance of the relationships among the predictor variables and the dependence of the multivariate model coefficients on the choice of these variables are stressed. Finally, concepts in regression model building are discussed.
The linear-non-linear frontier for the Goldstone Higgs
Gavela, M.B.; Saa, S. [IFT-UAM/CSIC, Universidad Autonoma de Madrid, Departamento de Fisica Teorica y Instituto de Fisica Teorica, Madrid (Spain); Kanshin, K. [Universita di Padova, Dipartimento di Fisica e Astronomia ' G. Galilei' , Padua (Italy); INFN, Padova (Italy); Machado, P.A.N. [IFT-UAM/CSIC, Universidad Autonoma de Madrid, Departamento de Fisica Teorica y Instituto de Fisica Teorica, Madrid (Spain); Fermi National Accelerator Laboratory, Theoretical Physics Department, Batavia, IL (United States)
2016-12-15
The minimal SO(5)/SO(4) σ-model is used as a template for the ultraviolet completion of scenarios in which the Higgs particle is a low-energy remnant of some high-energy dynamics, enjoying a (pseudo) Nambu-Goldstone-boson ancestry. Varying the σ mass allows one to sweep from the perturbative regime to the customary non-linear implementations. The low-energy benchmark effective non-linear Lagrangian for bosons and fermions is obtained, determining as well the operator coefficients including linear corrections. At first order in the latter, three effective bosonic operators emerge which are independent of the explicit soft breaking assumed. The Higgs couplings to vector bosons and fermions turn out to be quite universal: the linear corrections are proportional to the explicit symmetry-breaking parameters. Furthermore, we define an effective Yukawa operator which allows a simple parametrization and comparison of different heavy-fermion ultraviolet completions. In addition, one particular fermionic completion is explored in detail, obtaining the corresponding leading low-energy fermionic operators. (orig.)
Linearization: Geometric, Complex, and Conditional
Asghar Qadir
2012-01-01
Full Text Available Lie symmetry analysis provides a systematic method of obtaining exact solutions of nonlinear (systems of differential equations, whether partial or ordinary. Of special interest is the procedure that Lie developed to transform scalar nonlinear second-order ordinary differential equations to linear form. Not much work was done in this direction to start with, but recently there have been various developments. Here, first the original work of Lie (and the early developments on it, and then more recent developments based on geometry and complex analysis, apart from Lie’s own method of algebra (namely, Lie group theory, are reviewed. It is relevant to mention that much of the work is not linearization but uses the base of linearization.
Window observers for linear systems
Utkin Vadim
2000-01-01
Full Text Available Given a linear system x ˙ = A x + B u with output y = C x and a window function ω ( t , i.e., ∀ t , ω ( t ∈ {0,1 }, and assuming that the window function is Lebesgue measurable, we refer to the following observer, x ˆ = A x + B u + ω ( t L C ( x − x ˆ as a window observer. The stability issue is treated in this paper. It is proven that for linear time-invariant systems, the window observer can be stabilized by an appropriate design under a very mild condition on the window functions, albeit for linear time-varying system, some regularity of the window functions is required to achieve observer designs with the asymptotic stability. The corresponding design methods are developed. An example is included to illustrate the possible applications
Topics in quaternion linear algebra
Rodman, Leiba
2014-01-01
Quaternions are a number system that has become increasingly useful for representing the rotations of objects in three-dimensional space and has important applications in theoretical and applied mathematics, physics, computer science, and engineering. This is the first book to provide a systematic, accessible, and self-contained exposition of quaternion linear algebra. It features previously unpublished research results with complete proofs and many open problems at various levels, as well as more than 200 exercises to facilitate use by students and instructors. Applications presented in the book include numerical ranges, invariant semidefinite subspaces, differential equations with symmetries, and matrix equations. Designed for researchers and students across a variety of disciplines, the book can be read by anyone with a background in linear algebra, rudimentary complex analysis, and some multivariable calculus. Instructors will find it useful as a complementary text for undergraduate linear algebra courses...
Towards the International Linear Collider
Lopez-Fernandez, Ricardo
2006-01-01
The broad physics potential of e+e- linear colliders was recognized by the high energy physics community right after the end of LEP in 2000. In 2007, the Large Hadron Collider (LHC) now under construction at CERN will obtain its first collisions. The LHC, colliding protons with protons at 14 TeV, will discover a standard model Higgs boson over the full potential mass range, and should be sensitive to new physics into the several TeV range. The program for the Linear Collider (LC) will be set in the context of the discoveries made at the LHC. All the proposals for a Linear Collider will extend the discoveries and provide a wealth of measurements that are essential for giving deeper understanding of their meaning, and pointing the way to further evolution of particle physics in the future. For the mexican groups is the right time to join such an effort
Linear Synchronous Motor Repeatability Tests
Ward, C.R.
2002-01-01
A cart system using linear synchronous motors was being considered for the Plutonium Immobilization Plant (PIP). One of the applications in the PIP was the movement of a stack of furnace trays, filled with the waste form (pucks) from a stacking/unstacking station to several bottom loaded furnaces. A system was ordered to perform this function in the PIP Ceramic Prototype Test Facility (CPTF). This system was installed and started up in SRTC prior to being installed in the CPTF. The PIP was suspended and then canceled after the linear synchronous motor system was started up. This system was used to determine repeatability of a linear synchronous motor cart system for the Modern Pit Facility
Linearly polarized photons at ELSA
Eberhardt, Holger [Physikalisches Institut, Universitaet Bonn (Germany)
2009-07-01
To investigate the nucleon resonance regime in meson photoproduction, double polarization experiments are currently performed at the electron accelerator ELSA in Bonn. The experiments make use of a polarized target and circularly or linearly polarized photon beams. Linearly polarized photons are produced by coherent bremsstrahlung from an accurately aligned diamond crystal. The orientation of the crystal with respect to the electron beam is measured using the Stonehenge-Technique. Both, the energy of maximum polarization and the plane of polarization, can be deliberately chosen for the experiment. The linearly polarized beam provides the basis for the measurement of azimuthal beam asymmetries, such as {sigma} (unpolarized target) and G (polarized target). These observables are extracted in various single and multiple meson photoproduction channels.
Linear programming foundations and extensions
Vanderbei, Robert J
2001-01-01
Linear Programming: Foundations and Extensions is an introduction to the field of optimization. The book emphasizes constrained optimization, beginning with a substantial treatment of linear programming, and proceeding to convex analysis, network flows, integer programming, quadratic programming, and convex optimization. The book is carefully written. Specific examples and concrete algorithms precede more abstract topics. Topics are clearly developed with a large number of numerical examples worked out in detail. Moreover, Linear Programming: Foundations and Extensions underscores the purpose of optimization: to solve practical problems on a computer. Accordingly, the book is coordinated with free efficient C programs that implement the major algorithms studied: -The two-phase simplex method; -The primal-dual simplex method; -The path-following interior-point method; -The homogeneous self-dual methods. In addition, there are online JAVA applets that illustrate various pivot rules and variants of the simplex m...
Uniqueness theorems in linear elasticity
Knops, Robin John
1971-01-01
The classical result for uniqueness in elasticity theory is due to Kirchhoff. It states that the standard mixed boundary value problem for a homogeneous isotropic linear elastic material in equilibrium and occupying a bounded three-dimensional region of space possesses at most one solution in the classical sense, provided the Lame and shear moduli, A and J1 respectively, obey the inequalities (3 A + 2 J1) > 0 and J1>O. In linear elastodynamics the analogous result, due to Neumann, is that the initial-mixed boundary value problem possesses at most one solution provided the elastic moduli satisfy the same set of inequalities as in Kirchhoffs theorem. Most standard textbooks on the linear theory of elasticity mention only these two classical criteria for uniqueness and neglect altogether the abundant literature which has appeared since the original publications of Kirchhoff. To remedy this deficiency it seems appropriate to attempt a coherent description ofthe various contributions made to the study of uniquenes...
Bayes linear statistics, theory & methods
Goldstein, Michael
2007-01-01
Bayesian methods combine information available from data with any prior information available from expert knowledge. The Bayes linear approach follows this path, offering a quantitative structure for expressing beliefs, and systematic methods for adjusting these beliefs, given observational data. The methodology differs from the full Bayesian methodology in that it establishes simpler approaches to belief specification and analysis based around expectation judgements. Bayes Linear Statistics presents an authoritative account of this approach, explaining the foundations, theory, methodology, and practicalities of this important field. The text provides a thorough coverage of Bayes linear analysis, from the development of the basic language to the collection of algebraic results needed for efficient implementation, with detailed practical examples. The book covers:The importance of partial prior specifications for complex problems where it is difficult to supply a meaningful full prior probability specification...
Scalar-tensor linear inflation
Artymowski, Michał [Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków (Poland); Racioppi, Antonio, E-mail: Michal.Artymowski@uj.edu.pl, E-mail: Antonio.Racioppi@kbfi.ee [National Institute of Chemical Physics and Biophysics, Rävala 10, 10143 Tallinn (Estonia)
2017-04-01
We investigate two approaches to non-minimally coupled gravity theories which present linear inflation as attractor solution: a) the scalar-tensor theory approach, where we look for a scalar-tensor theory that would restore results of linear inflation in the strong coupling limit for a non-minimal coupling to gravity of the form of f (φ) R /2; b) the particle physics approach, where we motivate the form of the Jordan frame potential by loop corrections to the inflaton field. In both cases the Jordan frame potentials are modifications of the induced gravity inflationary scenario, but instead of the Starobinsky attractor they lead to linear inflation in the strong coupling limit.
Permafrost Hazards and Linear Infrastructure
Stanilovskaya, Julia; Sergeev, Dmitry
2014-05-01
The international experience of linear infrastructure planning, construction and exploitation in permafrost zone is being directly tied to the permafrost hazard assessment. That procedure should also consider the factors of climate impact and infrastructure protection. The current global climate change hotspots are currently polar and mountain areas. Temperature rise, precipitation and land ice conditions change, early springs occur more often. The big linear infrastructure objects cross the territories with different permafrost conditions which are sensitive to the changes in air temperature, hydrology, and snow accumulation which are connected to climatic dynamics. One of the most extensive linear structures built on permafrost worldwide are Trans Alaskan Pipeline (USA), Alaska Highway (Canada), Qinghai-Xizang Railway (China) and Eastern Siberia - Pacific Ocean Oil Pipeline (Russia). Those are currently being influenced by the regional climate change and permafrost impact which may act differently from place to place. Thermokarst is deemed to be the most dangerous process for linear engineering structures. Its formation and development depend on the linear structure type: road or pipeline, elevated or buried one. Zonal climate and geocryological conditions are also of the determining importance here. All the projects are of the different age and some of them were implemented under different climatic conditions. The effects of permafrost thawing have been recorded every year since then. The exploration and transportation companies from different countries maintain the linear infrastructure from permafrost degradation in different ways. The highways in Alaska are in a good condition due to governmental expenses on annual reconstructions. The Chara-China Railroad in Russia is under non-standard condition due to intensive permafrost response. Standards for engineering and construction should be reviewed and updated to account for permafrost hazards caused by the
A Linear Electromagnetic Piston Pump
Hogan, Paul H.
Advancements in mobile hydraulics for human-scale applications have increased demand for a compact hydraulic power supply. Conventional designs couple a rotating electric motor to a hydraulic pump, which increases the package volume and requires several energy conversions. This thesis investigates the use of a free piston as the moving element in a linear motor to eliminate multiple energy conversions and decrease the overall package volume. A coupled model used a quasi-static magnetic equivalent circuit to calculate the motor inductance and the electromagnetic force acting on the piston. The force was an input to a time domain model to evaluate the mechanical and pressure dynamics. The magnetic circuit model was validated with finite element analysis and an experimental prototype linear motor. The coupled model was optimized using a multi-objective genetic algorithm to explore the parameter space and maximize power density and efficiency. An experimental prototype linear pump coupled pistons to an off-the-shelf linear motor to validate the mechanical and pressure dynamics models. The magnetic circuit force calculation agreed within 3% of finite element analysis, and within 8% of experimental data from the unoptimized prototype linear motor. The optimized motor geometry also had good agreement with FEA; at zero piston displacement, the magnetic circuit calculates optimized motor force within 10% of FEA in less than 1/1000 the computational time. This makes it well suited to genetic optimization algorithms. The mechanical model agrees very well with the experimental piston pump position data when tuned for additional unmodeled mechanical friction. Optimized results suggest that an improvement of 400% of the state of the art power density is attainable with as high as 85% net efficiency. This demonstrates that a linear electromagnetic piston pump has potential to serve as a more compact and efficient supply of fluid power for the human scale.
Sparse Linear Identifiable Multivariate Modeling
Henao, Ricardo; Winther, Ole
2011-01-01
and bench-marked on artificial and real biological data sets. SLIM is closest in spirit to LiNGAM (Shimizu et al., 2006), but differs substantially in inference, Bayesian network structure learning and model comparison. Experimentally, SLIM performs equally well or better than LiNGAM with comparable......In this paper we consider sparse and identifiable linear latent variable (factor) and linear Bayesian network models for parsimonious analysis of multivariate data. We propose a computationally efficient method for joint parameter and model inference, and model comparison. It consists of a fully...
Quantized, piecewise linear filter network
Sørensen, John Aasted
1993-01-01
A quantization based piecewise linear filter network is defined. A method for the training of this network based on local approximation in the input space is devised. The training is carried out by repeatedly alternating between vector quantization of the training set into quantization classes...... and equalization of the quantization classes linear filter mean square training errors. The equalization of the mean square training errors is carried out by adapting the boundaries between neighbor quantization classes such that the differences in mean square training errors are reduced...
Correct Linearization of Einstein's Equations
Rabounski D.
2006-06-01
Full Text Available Regularly Einstein's equations can be reduced to a wave form (linearly dependent from the second derivatives of the space metric in the absence of gravitation, the space rotation and Christoffel's symbols. As shown here, the origin of the problem is that one uses the general covariant theory of measurement. Here the wave form of Einstein's equations is obtained in the terms of Zelmanov's chronometric invariants (physically observable projections on the observer's time line and spatial section. The obtained equations depend on solely the second derivatives even if gravitation, the space rotation and Christoffel's symbols. The correct linearization proves: the Einstein equations are completely compatible with weak waves of the metric.
Basic linear partial differential equations
Treves, Francois
1975-01-01
Focusing on the archetypes of linear partial differential equations, this text for upper-level undergraduates and graduate students features most of the basic classical results. The methods, however, are decidedly nontraditional: in practically every instance, they tend toward a high level of abstraction. This approach recalls classical material to contemporary analysts in a language they can understand, as well as exploiting the field's wealth of examples as an introduction to modern theories.The four-part treatment covers the basic examples of linear partial differential equations and their
Introduction to computational linear algebra
Nassif, Nabil; Erhel, Jocelyne
2015-01-01
Introduction to Computational Linear Algebra introduces the reader with a background in basic mathematics and computer programming to the fundamentals of dense and sparse matrix computations with illustrating examples. The textbook is a synthesis of conceptual and practical topics in ""Matrix Computations."" The book's learning outcomes are twofold: to understand state-of-the-art computational tools to solve matrix computations problems (BLAS primitives, MATLAB® programming) as well as essential mathematical concepts needed to master the topics of numerical linear algebra. It is suitable for s
Linear feedback controls the essentials
Haidekker, Mark A
2013-01-01
The design of control systems is at the very core of engineering. Feedback controls are ubiquitous, ranging from simple room thermostats to airplane engine control. Helping to make sense of this wide-ranging field, this book provides a new approach by keeping a tight focus on the essentials with a limited, yet consistent set of examples. Analysis and design methods are explained in terms of theory and practice. The book covers classical, linear feedback controls, and linear approximations are used when needed. In parallel, the book covers time-discrete (digital) control systems and juxtapos
Passive longitudinal phase space linearizer
P. Craievich
2010-03-01
Full Text Available We report on the possibility to passively linearize the bunch compression process in electron linacs for the next generation x-ray free electron lasers. This can be done by using the monopole wakefields in a dielectric-lined waveguide. The optimum longitudinal voltage loss over the length of the bunch is calculated in order to compensate both the second-order rf time curvature and the second-order momentum compaction terms. Thus, the longitudinal phase space after the compression process is linearized up to a fourth-order term introduced by the convolution between the bunch and the monopole wake function.
Generalized, Linear, and Mixed Models
McCulloch, Charles E; Neuhaus, John M
2011-01-01
An accessible and self-contained introduction to statistical models-now in a modernized new editionGeneralized, Linear, and Mixed Models, Second Edition provides an up-to-date treatment of the essential techniques for developing and applying a wide variety of statistical models. The book presents thorough and unified coverage of the theory behind generalized, linear, and mixed models and highlights their similarities and differences in various construction, application, and computational aspects.A clear introduction to the basic ideas of fixed effects models, random effects models, and mixed m
Emittance control in linear colliders
Ruth, R.D.
1991-01-01
Before completing a realistic design of a next-generation linear collider, the authors must first learn the lessons taught by the first generation, the SLC. Given that, they must make designs fault tolerant by including correction and compensation in the basic design. They must also try to eliminate these faults by improved alignment and stability of components. When these two efforts cross, they have a realistic design. The techniques of generation and control of emittance reviewed here provide a foundation for a design which can obtain the necessary luminosity in a next-generation linear collider
Linear contextual modal type theory
Schack-Nielsen, Anders; Schürmann, Carsten
Abstract. When one implements a logical framework based on linear type theory, for example the Celf system [?], one is immediately con- fronted with questions about their equational theory and how to deal with logic variables. In this paper, we propose linear contextual modal type theory that gives...... a mathematical account of the nature of logic variables. Our type theory is conservative over intuitionistic contextual modal type theory proposed by Nanevski, Pfenning, and Pientka. Our main contributions include a mechanically checked proof of soundness and a working implementation....
Vanilla Technicolor at Linear Colliders
T. Frandsen, Mads; Jarvinen, Matti; Sannino, Francesco
2011-01-01
We analyze the reach of Linear Colliders (LC)s for models of dynamical electroweak symmetry breaking. We show that LCs can efficiently test the compositeness scale, identified with the mass of the new spin-one resonances, till the maximum energy in the center-of-mass of the colliding leptons. In ...
Variational linear algebraic equations method
Moiseiwitsch, B.L.
1982-01-01
A modification of the linear algebraic equations method is described which ensures a variational bound on the phaseshifts for potentials having a definite sign at all points. The method is illustrated by the elastic scattering of s-wave electrons by the static field of atomic hydrogen. (author)
Feedback Systems for Linear Colliders
1999-01-01
Feedback systems are essential for stable operation of a linear collider, providing a cost-effective method for relaxing tight tolerances. In the Stanford Linear Collider (SLC), feedback controls beam parameters such as trajectory, energy, and intensity throughout the accelerator. A novel dithering optimization system which adjusts final focus parameters to maximize luminosity contributed to achieving record performance in the 1997-98 run. Performance limitations of the steering feedback have been investigated, and improvements have been made. For the Next Linear Collider (NLC), extensive feedback systems are planned as an integral part of the design. Feedback requirements for JLC (the Japanese Linear Collider) are essentially identical to NLC; some of the TESLA requirements are similar but there are significant differences. For NLC, algorithms which incorporate improvements upon the SLC implementation are being prototyped. Specialized systems for the damping rings, rf and interaction point will operate at high bandwidth and fast response. To correct for the motion of individual bunches within a train, both feedforward and feedback systems are planned. SLC experience has shown that feedback systems are an invaluable operational tool for decoupling systems, allowing precision tuning, and providing pulse-to-pulse diagnostics. Feedback systems for the NLC will incorporate the key SLC features and the benefits of advancing technologies
Aspects of robust linear regression
Davies, P.L.
1993-01-01
Section 1 of the paper contains a general discussion of robustness. In Section 2 the influence function of the Hampel-Rousseeuw least median of squares estimator is derived. Linearly invariant weak metrics are constructed in Section 3. It is shown in Section 4 that $S$-estimators satisfy an exact
Periodic linear differential stochastic processes
Kwakernaak, H.
1975-01-01
Periodic linear differential processes are defined and their properties are analyzed. Equivalent representations are discussed, and the solutions of related optimal estimation problems are given. An extension is presented of Kailath and Geesey’s [1] results concerning the innovations representation
Linear colliders for photon collisions
Anon.
1994-01-01
The enthusiasm of the first international workshop on photonphoton colliders and associated physics, held at the Lawrence Berkeley Laboratory from 28 March - 1 April, could have set a ball rolling. According to proponents of this physics, the particle physics one can study with a high energy linear collider is special and complements that of a hadron supercollider
Saturation and linear transport equation
Kutak, K.
2009-03-01
We show that the GBW saturation model provides an exact solution to the one dimensional linear transport equation. We also show that it is motivated by the BK equation considered in the saturated regime when the diffusion and the splitting term in the diffusive approximation are balanced by the nonlinear term. (orig.)
Parameterized Linear Longitudinal Airship Model
Kulczycki, Eric; Elfes, Alberto; Bayard, David; Quadrelli, Marco; Johnson, Joseph
2010-01-01
A parameterized linear mathematical model of the longitudinal dynamics of an airship is undergoing development. This model is intended to be used in designing control systems for future airships that would operate in the atmospheres of Earth and remote planets. Heretofore, the development of linearized models of the longitudinal dynamics of airships has been costly in that it has been necessary to perform extensive flight testing and to use system-identification techniques to construct models that fit the flight-test data. The present model is a generic one that can be relatively easily specialized to approximate the dynamics of specific airships at specific operating points, without need for further system identification, and with significantly less flight testing. The approach taken in the present development is to merge the linearized dynamical equations of an airship with techniques for estimation of aircraft stability derivatives, and to thereby make it possible to construct a linearized dynamical model of the longitudinal dynamics of a specific airship from geometric and aerodynamic data pertaining to that airship. (It is also planned to develop a model of the lateral dynamics by use of the same methods.) All of the aerodynamic data needed to construct the model of a specific airship can be obtained from wind-tunnel testing and computational fluid dynamics
Linear Methods for Image Interpolation
Pascal Getreuer
2011-09-01
Full Text Available We discuss linear methods for interpolation, including nearest neighbor, bilinear, bicubic, splines, and sinc interpolation. We focus on separable interpolation, so most of what is said applies to one-dimensional interpolation as well as N-dimensional separable interpolation.
Directivity of basic linear arrays
Bach, Henning
1970-01-01
For a linear uniform array ofnelements, an expression is derived for the directivity as a function of the spacing and the phase constants. The cases of isotropic elements, collinear short dipoles, and parallel short dipoles are included. The formula obtained is discussed in some detail and contour...
Data Compression with Linear Algebra
Etler, David
2015-01-01
A presentation on the applications of linear algebra to image compression. Covers entropy, the discrete cosine transform, thresholding, quantization, and examples of images compressed with DCT. Given in Spring 2015 at Ocean County College as part of the honors program.
175 Years of Linear Programming
polynomial-time solvability of linear programming, that is, testing if a polyhedron Q E ~ ... Q is rational, i.e. all extreme points and rays of Q are ra- tional vectors or ..... rithrll terminates with an interior solution, a post-processing step is usually ...
175 Years of Linear Programming
Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 10. 175 Years of Linear Programming - Max Flow = Min Cut. Vijay Chandru M R Rao. Series Article Volume 4 Issue 10 October 1999 pp 22-39. Fulltext. Click here to view fulltext PDF. Permanent link:
Linear collider systems and costs
Loew, G.A.
1993-05-01
The purpose of this paper is to examine some of the systems and sub-systems involved in so-called ''conventional'' e + e - linear colliders and to study how their design affects the overall cost of these machines. There are presently a total of at least six 500 GeV c. of m. linear collider projects under study in the world. Aside from TESLA (superconducting linac at 1.3 GHz) and CLIC (two-beam accelerator with main linac at 30GHz), the other four proposed e + e - linear colliders can be considered ''conventional'' in that their main linacs use the proven technique of driving room temperature accelerator sections with pulsed klystrons and modulators. The centrally distinguishing feature between these projects is their main linac rf frequency: 3 GHz for the DESY machine, 11.424 GHz for the SLAC and JLC machines, and 14 GHz for the VLEPP machine. The other systems, namely the electron and positron sources, preaccelerators, compressors, damping rings and final foci, are fairly similar from project to project. Probably more than 80% of the cost of these linear colliders will be incurred in the two main linacs facing each other and it is therefore in their design and construction that major savings or extra costs may be found
Linear accelerators of the future
Loew, G.A.
1986-07-01
Some of the requirements imposed on future linear accelerators to be used in electron-positron colliders are reviewed, as well as some approaches presently being examined for meeting those requirements. RF sources for use in these linacs are described, as well as wakefields, single bunches, and multiple-bunch trains
175 Years of Linear Programming
Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 5. 175 Years of Linear Programming - Pune's Gift. Vijay Chandru M R Rao. Series Article Volume 4 Issue 5 May ... Computer Science and Automation, IISc Bangalore 560012, India. Director, Indian Institute of Management, Bannerghatta Road, ...
Spaces of Piecewise Linear Manifolds
Gomez Lopez, Mauricio Esteban
Abstract In this thesis we introduce Δ-set ψPLd(RN) which we regard as the piecewise linear analogue of the space ψd(RN) of smooth d-dimensional submanifoldsin RN introduced by Galatius in [4]. Using ψPLd(RN) we define a bi-Δ-set Cd(RN)•,• ( whose geometric realization BCPLd(RN) = llCd(RN)•,•ll ......Abstract In this thesis we introduce Δ-set ψPLd(RN) which we regard as the piecewise linear analogue of the space ψd(RN) of smooth d-dimensional submanifoldsin RN introduced by Galatius in [4]. Using ψPLd(RN) we define a bi-Δ-set Cd(RN)•,• ( whose geometric realization BCPLd(RN) = ll...... BCPLd (RN) ≅ ΩN–1lψPLd (RN)•l when N — d ≥ 3. The proof of the main theorem relies on properties of ψPLd (RN) • which arise from the fact that this Δ-set can be obtained from a more general contravariant functor PL op → Sets defined on the category of finite dimensional polyhedraand piecewise linear...... maps, and on a fiberwise transversality result for piecewise linear submersions whose fibers are contained in R × (-1,1)N-1 ⊆ RN . For the proof of this transversality result we use a theorem of Hudson on extensions of piecewise linear isotopies which is why we need to include the condition N — d ≥ 3...
Linear fixed-field multipass arcs for recirculating linear accelerators
V. S. Morozov
2012-06-01
Full Text Available Recirculating linear accelerators (RLA’s provide a compact and efficient way of accelerating particle beams to medium and high energies by reusing the same linac for multiple passes. In the conventional scheme, after each pass, the different energy beams coming out of the linac are separated and directed into appropriate arcs for recirculation, with each pass requiring a separate fixed-energy arc. In this paper we present a concept of an RLA return arc based on linear combined-function magnets, in which two and potentially more consecutive passes with very different energies are transported through the same string of magnets. By adjusting the dipole and quadrupole components of the constituting linear combined-function magnets, the arc is designed to be achromatic and to have zero initial and final reference orbit offsets for all transported beam energies. We demonstrate the concept by developing a design for a droplet-shaped return arc for a dogbone RLA capable of transporting two beam passes with momenta different by a factor of 2. We present the results of tracking simulations of the two passes and lay out the path to end-to-end design and simulation of a complete dogbone RLA.
Storesund, R.; Chin, A.; Florsheim, J. L.; O'Hirok, L.; Williams, K.; Austin, K. E.
2014-12-01
Mountains areas are increasingly susceptible to wildfires because of warming climates. Although knowledge of the hydro-geomorphological impacts of wildfire has advanced in recent years, much is still unknown regarding how environmental fluxes move through burned watersheds. Because of the loss of vegetation and hydrophobic soils, flash floods often accompany elevated runoff events from burned watersheds, making direct process measurements challenging. Direct measurements are also only partly successful at capturing the spatial variations of post-fire effects. Coupled with short temporal windows for observing such responses, opportunities are often missed for collecting data needed for developing predictive models. Terrestrial LiDAR scanning (TLS) of burned areas allows detailed documentation of the post-fire topography to cm-level accuracy, providing pictures of geomorphic responses not previously possible. This paper reports a comparative study of hillslope-channel interactions, using repeat TLS, in two contrasting environments. Burned by the 2012 Waldo Canyon Fire and 2013 Springs Fire, in Colorado and California respectively, the study sites share many similarities including steep erosive slopes, small drainage areas, and step-pool channel morphologies. TLS provided a tool to test the central hypothesis that, dry ravel, distinct in the California Mediterranean environment, would prompt a greater sedimentological response from the Springs Fire compared to the Waldo Canyon Fire. At selected sites in each area, TLS documented baseline conditions immediately following the fire. Repeat scanning after major storms allowed detection of changes in the landscape. Results show a tendency for sedimentation in river channels in the study sites interacting with dry ravel on hillslopes, whereas erosion dominated the response from the Waldo Canyon Fire with an absence of dry ravel. These data provide clues to developing generalizations for post-fire effects at regional scales
Multivariate covariance generalized linear models
Bonat, W. H.; Jørgensen, Bent
2016-01-01
are fitted by using an efficient Newton scoring algorithm based on quasi-likelihood and Pearson estimating functions, using only second-moment assumptions. This provides a unified approach to a wide variety of types of response variables and covariance structures, including multivariate extensions......We propose a general framework for non-normal multivariate data analysis called multivariate covariance generalized linear models, designed to handle multivariate response variables, along with a wide range of temporal and spatial correlation structures defined in terms of a covariance link...... function combined with a matrix linear predictor involving known matrices. The method is motivated by three data examples that are not easily handled by existing methods. The first example concerns multivariate count data, the second involves response variables of mixed types, combined with repeated...
Systems of Inhomogeneous Linear Equations
Scherer, Philipp O. J.
Many problems in physics and especially computational physics involve systems of linear equations which arise e.g. from linearization of a general nonlinear problem or from discretization of differential equations. If the dimension of the system is not too large standard methods like Gaussian elimination or QR decomposition are sufficient. Systems with a tridiagonal matrix are important for cubic spline interpolation and numerical second derivatives. They can be solved very efficiently with a specialized Gaussian elimination method. Practical applications often involve very large dimensions and require iterative methods. Convergence of Jacobi and Gauss-Seidel methods is slow and can be improved by relaxation or over-relaxation. An alternative for large systems is the method of conjugate gradients.
Linear accelerator for radioisotope production
Hansborough, L.D.; Hamm, R.W.; Stovall, J.E.
1982-02-01
A 200- to 500-μA source of 70- to 90-MeV protons would be a valuable asset to the nuclear medicine program. A linear accelerator (linac) can achieve this performance, and it can be extended to even higher energies and currents. Variable energy and current options are available. A 70-MeV linac is described, based on recent innovations in linear accelerator technology; it would be 27.3 m long and cost approx. $6 million. By operating the radio-frequency (rf) power system at a level necessary to produce a 500-μA beam current, the cost of power deposited in the radioisotope-production target is comparable with existing cyclotrons. If the rf-power system is operated at full power, the same accelerator is capable of producing an 1140-μA beam, and the cost per beam watt on the target is less than half that of comparable cyclotrons
Linear regression in astronomy. II
Feigelson, Eric D.; Babu, Gutti J.
1992-01-01
A wide variety of least-squares linear regression procedures used in observational astronomy, particularly investigations of the cosmic distance scale, are presented and discussed. The classes of linear models considered are (1) unweighted regression lines, with bootstrap and jackknife resampling; (2) regression solutions when measurement error, in one or both variables, dominates the scatter; (3) methods to apply a calibration line to new data; (4) truncated regression models, which apply to flux-limited data sets; and (5) censored regression models, which apply when nondetections are present. For the calibration problem we develop two new procedures: a formula for the intercept offset between two parallel data sets, which propagates slope errors from one regression to the other; and a generalization of the Working-Hotelling confidence bands to nonstandard least-squares lines. They can provide improved error analysis for Faber-Jackson, Tully-Fisher, and similar cosmic distance scale relations.
Squares of Random Linear Codes
Cascudo Pueyo, Ignacio; Cramer, Ronald; Mirandola, Diego
2015-01-01
a positive answer, for codes of dimension $k$ and length roughly $\\frac{1}{2}k^2$ or smaller. Moreover, the convergence speed is exponential if the difference $k(k+1)/2-n$ is at least linear in $k$. The proof uses random coding and combinatorial arguments, together with algebraic tools involving the precise......Given a linear code $C$, one can define the $d$-th power of $C$ as the span of all componentwise products of $d$ elements of $C$. A power of $C$ may quickly fill the whole space. Our purpose is to answer the following question: does the square of a code ``typically'' fill the whole space? We give...
Linear inflation from quartic potential
Kannike, Kristjan; Racioppi, Antonio [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia); Raidal, Martti [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia); Institute of Physics, University of Tartu,Tartu (Estonia)
2016-01-07
We show that if the inflaton has a non-minimal coupling to gravity and the Planck scale is dynamically generated, the results of Coleman-Weinberg inflation are confined in between two attractor solutions: quadratic inflation, which is ruled out by the recent measurements, and linear inflation which, instead, is in the experimental allowed region. The minimal scenario has only one free parameter — the inflaton’s non-minimal coupling to gravity — that determines all physical parameters such as the tensor-to-scalar ratio and the reheating temperature of the Universe. Should the more precise future measurements of inflationary parameters point towards linear inflation, further interest in scale-invariant scenarios would be motivated.
Computational linear and commutative algebra
Kreuzer, Martin
2016-01-01
This book combines, in a novel and general way, an extensive development of the theory of families of commuting matrices with applications to zero-dimensional commutative rings, primary decompositions and polynomial system solving. It integrates the Linear Algebra of the Third Millennium, developed exclusively here, with classical algorithmic and algebraic techniques. Even the experienced reader will be pleasantly surprised to discover new and unexpected aspects in a variety of subjects including eigenvalues and eigenspaces of linear maps, joint eigenspaces of commuting families of endomorphisms, multiplication maps of zero-dimensional affine algebras, computation of primary decompositions and maximal ideals, and solution of polynomial systems. This book completes a trilogy initiated by the uncharacteristically witty books Computational Commutative Algebra 1 and 2 by the same authors. The material treated here is not available in book form, and much of it is not available at all. The authors continue to prese...
Perspectives on large linear colliders
Richter, B.
1987-11-01
Three main items in the design of large linear colliders are presented. The first is the interrelation of energy and luminosity requirements. These two items impose severe constraints on the accelerator builder who must design a machine to meet the needs of experimentl high energy physics rather than designing a machine for its own sake. An introduction is also given for linear collider design, concentrating on what goes on at the collision point, for still another constraint comes here from the beam-beam interaction which further restricts the choices available to the accelerator builder. The author also gives his impressions of the state of the technology available for building these kinds of machines within the next decade. The paper concludes with a brief recommendation for how we can all get on with the work faster, and hope to realize these machines sooner by working together. 10 refs., 9 figs
Forms and Linear Network Codes
Hansen, Johan P.
We present a general theory to obtain linear network codes utilizing forms and obtain explicit families of equidimensional vector spaces, in which any pair of distinct vector spaces intersect in the same small dimension. The theory is inspired by the methods of the author utilizing the osculating...... spaces of Veronese varieties. Linear network coding transmits information in terms of a basis of a vector space and the information is received as a basis of a possibly altered vector space. Ralf Koetter and Frank R. Kschischang introduced a metric on the set af vector spaces and showed that a minimal...... distance decoder for this metric achieves correct decoding if the dimension of the intersection of the transmitted and received vector space is sufficiently large. The vector spaces in our construction are equidistant in the above metric and the distance between any pair of vector spaces is large making...
Perspectives on large Linear Colliders
Richter, B.
1987-01-01
The accelerator community now generally agrees that the Linear Collider is the most cost-effective technology for reaching much higher energies in the center-of-mass than can be attained in the largest of the e + e - storage rings, LEP. Indeed, even as the first linear collider, the SLC at SLAC, is getting ready to begin operations groups, at SLAC, Novosibirsk, CERN and KEK are doing R and D and conceptual design studies on a next generation machine in the 1 TeV energy region. In this perspectives talk I do not want to restrict my comments to any particular design, and so I will talk about a high-energy machine as the NLC, which is shorthand for the Next Linear Collider, and taken to mean a machine with a center-of-mass energy someplace in the 0.5 to 2 TeV energy range with sufficient luminosity to carry out a meaningful experimental program. I want to discuss three main items with you. The first is the interrelation of energy and luminosity requirements. These two items impose severe constraints on the accelerator builder. Next, I will give an introduction to linear collider design, concentrating on what goes on at the collision point, for still another constraint comes here from the beam-beam interaction which further restricts the choices available to the accelerator builder.Then, I want to give my impressions of the state of the technology available for building these kinds of machines within the next decade
Linear gate with prescaled window
Koch, J; Bissem, H H; Krause, H; Scobel, W [Hamburg Univ. (Germany, F.R.). 1. Inst. fuer Experimentalphysik
1978-07-15
An electronic circuit is described that combines the features of a linear gate, a single channel analyzer and a prescaler. It allows selection of a pulse height region between two adjustable thresholds and scales the intensity of the spectrum within this window down by a factor 2sup(N) (0<=N<=9), whereas the complementary part of the spectrum is transmitted without being affected.
Stanford Linear Collider magnet positioning
Wand, B.T.
1991-08-01
For the installation of the Stanford Linear Collider (SLC) the positioning and alignment of the beam line components was performed in several individual steps. In the following the general procedures for each step are outlined. The calculation of ideal coordinates for the magnets in the entire SLC will be discussed in detail. Special emphasis was given to the mathematical algorithms and geometry used in the programs to calculate these ideal positions. 35 refs., 21 figs
Linear positivity and virtual probability
Hartle, James B.
2004-01-01
We investigate the quantum theory of closed systems based on the linear positivity decoherence condition of Goldstein and Page. The objective of any quantum theory of a closed system, most generally the universe, is the prediction of probabilities for the individual members of sets of alternative coarse-grained histories of the system. Quantum interference between members of a set of alternative histories is an obstacle to assigning probabilities that are consistent with the rules of probability theory. A quantum theory of closed systems therefore requires two elements: (1) a condition specifying which sets of histories may be assigned probabilities and (2) a rule for those probabilities. The linear positivity condition of Goldstein and Page is the weakest of the general conditions proposed so far. Its general properties relating to exact probability sum rules, time neutrality, and conservation laws are explored. Its inconsistency with the usual notion of independent subsystems in quantum mechanics is reviewed. Its relation to the stronger condition of medium decoherence necessary for classicality is discussed. The linear positivity of histories in a number of simple model systems is investigated with the aim of exhibiting linearly positive sets of histories that are not decoherent. The utility of extending the notion of probability to include values outside the range of 0-1 is described. Alternatives with such virtual probabilities cannot be measured or recorded, but can be used in the intermediate steps of calculations of real probabilities. Extended probabilities give a simple and general way of formulating quantum theory. The various decoherence conditions are compared in terms of their utility for characterizing classicality and the role they might play in further generalizations of quantum mechanics
Order-constrained linear optimization.
Tidwell, Joe W; Dougherty, Michael R; Chrabaszcz, Jeffrey S; Thomas, Rick P
2017-11-01
Despite the fact that data and theories in the social, behavioural, and health sciences are often represented on an ordinal scale, there has been relatively little emphasis on modelling ordinal properties. The most common analytic framework used in psychological science is the general linear model, whose variants include ANOVA, MANOVA, and ordinary linear regression. While these methods are designed to provide the best fit to the metric properties of the data, they are not designed to maximally model ordinal properties. In this paper, we develop an order-constrained linear least-squares (OCLO) optimization algorithm that maximizes the linear least-squares fit to the data conditional on maximizing the ordinal fit based on Kendall's τ. The algorithm builds on the maximum rank correlation estimator (Han, 1987, Journal of Econometrics, 35, 303) and the general monotone model (Dougherty & Thomas, 2012, Psychological Review, 119, 321). Analyses of simulated data indicate that when modelling data that adhere to the assumptions of ordinary least squares, OCLO shows minimal bias, little increase in variance, and almost no loss in out-of-sample predictive accuracy. In contrast, under conditions in which data include a small number of extreme scores (fat-tailed distributions), OCLO shows less bias and variance, and substantially better out-of-sample predictive accuracy, even when the outliers are removed. We show that the advantages of OCLO over ordinary least squares in predicting new observations hold across a variety of scenarios in which researchers must decide to retain or eliminate extreme scores when fitting data. © 2017 The British Psychological Society.
Segmented rail linear induction motor
Cowan, Jr., Maynard; Marder, Barry M.
1996-01-01
A segmented rail linear induction motor has a segmented rail consisting of a plurality of nonferrous electrically conductive segments aligned along a guideway. The motor further includes a carriage including at least one pair of opposed coils fastened to the carriage for moving the carriage. A power source applies an electric current to the coils to induce currents in the conductive surfaces to repel the coils from adjacent edges of the conductive surfaces.
Linear polarization of BY Draconis
Koch, R.H.; Pfeiffer, R.J.
1976-01-01
Linear polarization measurements are reported in four bandpasses for the flare star BY Dra. The red polarization is intrinsically variable at a confidence level greater than 99 percent. On a time scale of many months, the variability is not phase-locked to either a rotational or a Keplerian ephemeris. The observations of the three other bandpasses are useful principally to indicate a polarization spectrum rising toward shorter wavelengths
Linear morphea with secondary mucinosis
Khandpur Sujay
2009-01-01
Full Text Available Secondary mucin deposition in the skin is a common feature of lupus erythematosus and dermatomyositis. In scleroderma, it occurs uncommonly or in small amount. We describe a 7-year-old boy with progressive, linear, bound-down plaques involving the thighs, lower abdomen and back with no systemic involvement. Histopathology showed features of scleroderma with abundant mucin deposition in the reticular dermis. This report highlights excessive mucin deposition in lesions of morphea.
Cast dielectric composite linear accelerator
Sanders, David M [Livermore, CA; Sampayan, Stephen [Manteca, CA; Slenes, Kirk [Albuquerque, NM; Stoller, H M [Albuquerque, NM
2009-11-10
A linear accelerator having cast dielectric composite layers integrally formed with conductor electrodes in a solventless fabrication process, with the cast dielectric composite preferably having a nanoparticle filler in an organic polymer such as a thermosetting resin. By incorporating this cast dielectric composite the dielectric constant of critical insulating layers of the transmission lines of the accelerator are increased while simultaneously maintaining high dielectric strengths for the accelerator.
Introduction to Microwave Linear [Accelerators
Whittum, David H
1999-01-04
The elements of microwave linear accelerators are introduced starting with the principles of acceleration and accelerating structures. Considerations for microwave structure modeling and design are developed from an elementary point of view. Basic elements of microwave electronics are described for application to the accelerator circuit and instrumentation. Concepts of beam physics are explored together with examples of common beamline instruments. Charged particle optics and lattice diagnostics are introduced. Considerations for fixed-target and colliding-beam experimentation are summarized.
Positive Quasi Linear Operator Formulation
Berry, L.A.; Jaeger, E.F.
2005-01-01
Expressions for the RF quasi-linear operator are biquadratic sums over the Fourier modes (or FLR equivalent) that describe the RF electric field with a kernel that is a function of the two wave vectors, k-vector L and k-vector R , in the sum. As a result of either an implicit or explicit average over field lines or flux surfaces, this kernel only depends on one parallel wave vector, conventionally k R -vector. When k-vector is an independent component of the representation for E, the sums are demonstrably positive. However, except for closed field line systems, k-vector is dependent on the local direction of the equilibrium magnetic field, and, empirically, the absorbed energy and quasi-linear diffusion coefficients are observed to have negative features. We have formally introduced an independent k-vector sum by Fourier transforming the RF electric field (assuming straight field lines) using a field-line-length coordinate. The resulting expression is positive. We have modeled this approach by calculating the quasi linear operator for 'modes' with fixed k-vector. We form these modes by discretizing k-vector and then assigning all of the Fourier components with k-vectorthat fall within a given k-vector bin to that k-vector mode. Results will be shown as a function of the number of bins. Future work will involve implementing the expressions derived from the Fourier transform and evaluating the dependence on field line length
BLAS- BASIC LINEAR ALGEBRA SUBPROGRAMS
Krogh, F. T.
1994-01-01
The Basic Linear Algebra Subprogram (BLAS) library is a collection of FORTRAN callable routines for employing standard techniques in performing the basic operations of numerical linear algebra. The BLAS library was developed to provide a portable and efficient source of basic operations for designers of programs involving linear algebraic computations. The subprograms available in the library cover the operations of dot product, multiplication of a scalar and a vector, vector plus a scalar times a vector, Givens transformation, modified Givens transformation, copy, swap, Euclidean norm, sum of magnitudes, and location of the largest magnitude element. Since these subprograms are to be used in an ANSI FORTRAN context, the cases of single precision, double precision, and complex data are provided for. All of the subprograms have been thoroughly tested and produce consistent results even when transported from machine to machine. BLAS contains Assembler versions and FORTRAN test code for any of the following compilers: Lahey F77L, Microsoft FORTRAN, or IBM Professional FORTRAN. It requires the Microsoft Macro Assembler and a math co-processor. The PC implementation allows individual arrays of over 64K. The BLAS library was developed in 1979. The PC version was made available in 1986 and updated in 1988.
Test accelerator for linear collider
Takeda, S.; Akai, K.; Akemoto, M.; Araki, S.; Hayano, H.; Hugo, T.; Ishihara, N.; Kawamoto, T.; Kimura, Y.; Kobayashi, H.; Kubo, T.; Kurokawa, S.; Matsumoto, H.; Mizuno, H.; Odagiri, J.; Otake, Y.; Sakai, H.; Shidara, T.; Shintake, T.; Suetake, M.; Takashima, T.; Takata, K.; Takeuchi, Y.; Urakawa, J.; Yamamoto, N.; Yokoya, K.; Yoshida, M.; Yoshioka, M.; Yamaoka, Y.
1989-01-01
KEK has proposed to build Test Accelerator Facility (TAF) capable of producing a 2.5 GeV electron beam for the purpose of stimulating R ampersand D for linear collider in TeV region. The TAF consists of a 1.5 GeV S-band linear accelerator, 1.5 GeV damping ring and 1.0 GeV X-band linear accelerator. The TAF project will be carried forward in three phases. Through Phase-I and Phase-II, the S-band and X-band linacs will be constructed, and in Phase-III, the damping ring will be completed. The construction of TAF Phase-I has started, and the 0.2 GeV S-band injector linac has been almost completed. The Phase-I linac is composed of a 240 keV electron gun, subharmonic bunchers, prebunchers and traveling buncher followed by high-gradient accelerating structures. The SLAC 5045 klystrons are driven at 450 kV in order to obtain the rf-power of 100 MW in a 1 μs pulse duration. The rf-power from a pair of klystrons are combined into an accelerating structure. The accelerating gradient up to 100 MeV/m will be obtained in a 0.6 m long structure. 5 refs., 3 figs., 2 tabs
Orthogonal sparse linear discriminant analysis
Liu, Zhonghua; Liu, Gang; Pu, Jiexin; Wang, Xiaohong; Wang, Haijun
2018-03-01
Linear discriminant analysis (LDA) is a linear feature extraction approach, and it has received much attention. On the basis of LDA, researchers have done a lot of research work on it, and many variant versions of LDA were proposed. However, the inherent problem of LDA cannot be solved very well by the variant methods. The major disadvantages of the classical LDA are as follows. First, it is sensitive to outliers and noises. Second, only the global discriminant structure is preserved, while the local discriminant information is ignored. In this paper, we present a new orthogonal sparse linear discriminant analysis (OSLDA) algorithm. The k nearest neighbour graph is first constructed to preserve the locality discriminant information of sample points. Then, L2,1-norm constraint on the projection matrix is used to act as loss function, which can make the proposed method robust to outliers in data points. Extensive experiments have been performed on several standard public image databases, and the experiment results demonstrate the performance of the proposed OSLDA algorithm.
Core seismic behaviour: linear and non-linear models
Bernard, M.; Van Dorsselaere, M.; Gauvain, M.; Jenapierre-Gantenbein, M.
1981-08-01
The usual methodology for the core seismic behaviour analysis leads to a double complementary approach: to define a core model to be included in the reactor-block seismic response analysis, simple enough but representative of basic movements (diagrid or slab), to define a finer core model, with basic data issued from the first model. This paper presents the history of the different models of both kinds. The inert mass model (IMM) yielded a first rough diagrid movement. The direct linear model (DLM), without shocks and with sodium as an added mass, let to two different ones: DLM 1 with independent movements of the fuel and radial blanket subassemblies, and DLM 2 with a core combined movement. The non-linear (NLM) ''CORALIE'' uses the same basic modelization (Finite Element Beams) but accounts for shocks. It studies the response of a diameter on flats and takes into account the fluid coupling and the wrapper tube flexibility at the pad level. Damping consists of one modal part of 2% and one part due to shocks. Finally, ''CORALIE'' yields the time-history of the displacements and efforts on the supports, but damping (probably greater than 2%) and fluid-structures interaction are still to be precised. The validation experiments were performed on a RAPSODIE core mock-up on scale 1, in similitude of 1/3 as to SPX 1. The equivalent linear model (ELM) was developed for the SPX 1 reactor-block response analysis and a specified seismic level (SB or SM). It is composed of several oscillators fixed to the diagrid and yields the same maximum displacements and efforts than the NLM. The SPX 1 core seismic analysis with a diagrid input spectrum which corresponds to a 0,1 g group acceleration, has been carried out with these models: some aspects of these calculations are presented here