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Our long-term scientific goals are to understand the dynamics and identify mechanisms of small-scale processes i.e., internal tides, inertial waves, nonlinear internal waves (NLIWs), and turbulence mixing in the ocean and thereby help develop improved parameterizations of mixing for ocean models. Mixing within the stratified ocean is a particular focus as the complex interplay of internal waves from a variety of sources and turbulence makes this a current locus of uncertainty. For this study, our focus is on the generation, propagation, evolution, and dissipation of small-scale internal waves and internal tides as the Kuroshio and barotropic tides interact with the two prominent submarine ridges in Luzon Strait. The primary objectives of this observational program are to quantify 1) the generation of NLIWs and internal tides in the vicinity of Luzon Strait, 2) the energy flux of NLIWs and internal tides into the Pacific Ocean and South China Sea (SCS), 3) the effects of the Kuroshio on the generation and propagation of NLIWs and internal tides, 4) the seasonal variation of NLIWs and internal tides, and 5) to study other small-scale processes, e.g., hydraulics and instabilities along internal tidal beams and at the Kuroshio front.

Environmentally caused false alarms (FA) and false targets (FT) present some of the most difficult challenges for modern torpedo systems in systems in shallow water. In many cases, the mechanism for FA/FT is clear: scattering from exposed rock on the seafloor, e.g., rock outcrops and ridges. The long-term goals of this research program aim primarily to increase our understanding of and simulation capability for weapons-frequency acoustic scattering from rock outcrops. This knowledge will be used to develop methods for simulating FA/FT in areas of rock outcrops, for predicting where high FA/FT areas might occur and for predicting the influence of parameters such as slope or aspect on FA/FT levels. This effort will also allow the performance of sonar systems to be predicted for rocky environments, which will allow the negative impact of non-Rayleigh clutter on detection and classification to be minimized or robust signal processing methods to be developed or tested. Knowledge gained might also lead to methods for environmental assessment techniques for the characterization of rocky areas for example at test sites.

Based on the fact that conformal maps preserve contacts of surfaces with hyperspheres, we introduce the concept of strong principal lines on surfaces in ℝ4 and obtain conformally invariant differential 1-forms along them. The zeros of these 1-forms are respectively characterized as ridges (singularities of squared-distance functions of type A k ,k≥4) and higher order semiumbilics (singularities of type D k ,k≥5). As a consequence we obtain that any closed orientable surface generically immersed in ℝ4 has at least 2 semiumbilic points of type D 5. We provide geometrical interpretations of these conformally invariant 1-forms in terms of the geometry of curves induced in the 5-dimensional de Sitter space and in the 5-dimensional lightcone.

In dit dossier de volgende artikelen: Bezint eer je begint; Beter en sneller maïs zaaien; Optimalisatie zaaitechniek bij witloof; Precisiezaai onder glas; Aardappeldrempels vermijden erosie.

Four well-identified tropical cyclones over the past century have been responsible for depositing distinct units of predominantly quartzose sand and gravel to form the most seaward beach ridge at several locations along the wet tropical coast of northeast Queensland, Australia. These units deposited by tropical cyclones display a key sedimentary signature characterized by a sharp basal erosional contact, a coarser grain size than the underlying facies and a coarse-skewed trend toward the base. Coarse-skewed distributions with minimal change in mean grain size also characterize the upper levels of the high-energy deposited units at locations within the zone of maximum onshore winds during the tropical cyclone. These same coarse skew distributions are not apparent in sediments deposited at locations where predominantly offshore winds occurred during the cyclone, which in the case of northeast Australia is north of the eye-crossing location. These sedimentary signatures, along with the geochemical indicators and the degraded nature of the microfossil assemblages, have proven to be useful proxies to identify storm-deposited units within the study site and can also provide useful proxies in older beach ridges where advanced pedogenesis has obscured visual stratigraphic markers. As a consequence, more detailed long-term histories of storms and tropical cyclones can now be developed.

A new meltpond parameterization has been developed for the CICE sea ice model, taking advantage of the level ice tracer available in the model. The ponds evolve according to physically based process descriptions assuming a depth-area ratio for changes in pond volume. A novel aspect of the new scheme is that the ponds are carried as tracers on the level ice area of each thickness category, thus limiting their spatial extent based on the simulated sea ice topography. This limiting is meant to approximate the horizontal drainage of melt water into depressions in ice floes. Simulated melt pond processes include collection of liquid melt water and rain into ponds, drainage through permeable sea ice or over the edges of floes, infiltration of snow by pond water, and refreezing of ponds. Furthermore, snow that falls on top of ponds whose top surface has refrozen blocks radiation from penetrating into the ponds and sea ice below. Along with a control simulation, we present a range of sensitivity tests to parameters related to each subprocess described by the parameterization. With the exception of one parameter that alters the albedo of snow-covered pond ice, results are not highly sensitive to these parameters unless an entire process is removed. The snow simulation itself is critical, because the volume of snow deposition and rate of snow melt largely determine the timing and extent of the simulated melt ponds. Nevertheless, compensating effects moderate the model's sensitivity to precipitation changes. For instance, infiltration of the snow by melt water postpones the appearance of ponds and the subsequent acceleration of melting through albedo feedback, while snow on top of refrozen pond ice also reduces the ponds' effect on the radiation budget. By construction, the model simulation of level and ridged ice is also important for this parameterization. We find that as sea ice thins, either through time or when comparing sensitivity tests, the area of level ice increases., Pub in Ocean Modelling, v71 p26-42, 2013

A morphodynamic model has been applied to explain the characteristics of transverse sandbars observed in the inner surf zone of open beaches. The model describes the feedback between waves, rollers, depth-averaged currents and bed evolution, so that self-organized processes can develop., Postprint (published version)

Negentig procent van de pootmachines die Miedema bouwt, wordt geleverd met een aanaardkap. Alleen in thuisland Nederland lopen telers er nog niet warm voor. Een groep biologische telers reisde af naar Friesland voor een inhoudelijke discussie over de voors en tegens van directe rugopbouw.

Drempels tussen aardappelruggen zijn effectief tegen erosie. Dat blijkt uit onderzoek van PPO op praktijkbedrijven in Zuid-Limburg. Wanneer deze maatregel wordt erkend, zouden akkerbouwers op erosiegevoelige gronden de mogelijkheid om te ploegen toch kunnen behouden.

This report summarizes TARDEC-sponsored work at Oak Ridge National Laboratory (ORNL) during the FY11 involving low velocity ( 30 m/s or 65 mph) ball impact testing of Starphire soda lime silicate glass. The intent was to better understand low velocity impact response in the Starphire for sphere densities that bracketed that of rock. Five sphere materials were used: borosilicate glass, soda-lime silicate glass, steel, silicon nitride, and alumina. A gas gun was fabricated to produce controlled velocity delivery of the spheres against Starphire tile targets. Minimum impact velocities to initiate fracture in the Starphire were measured and interpreted in context to the kinetic energy of impact and the elastic property mismatch between the any of the five sphere-Starphire-target combinations.

Aardappelen poten en ruggen opbouwen in een werkgang gebeurt al enkele jaren. Fabrikanten staan niet stil en verbeteren hun technieken. Was deze methode voorheen alleen geschikt voor zandgrond, tegenwoordig is er ook op kleigrond interesse

Hij moet regelmatig opboksen tegen vooroordelen. Bijvoorbeeld dat het opbrengst zou kosten. En ook machinebouwers verkopen regelmatig ‘nee’. Toch gaat akkerbouwer Johan Huybregts stug door met het vervolmaken van zijn teeltsysteem op basis van een rijenafstand van 90 centimeter. Na de pootaardappelen volgen nu de wortelen.

Paulus van den Berg uit Bergeijk teelde in 2011 als proef een deel van zijn aardappelen op bedden in plaats van op ruggen. Met vochtsensoren mat de akkerbouwer tijdens het groeiseizoen het vochtgehalte in de bodem. De bedden bleken het water beter vast te houden. Hierdoor kon de aardappelteler twee beregeningsbeurten besparen.

The remote area of the Atlantic Ocean near the Antarctic Peninsula and the South Scotia Sea is a region where acoustic surveillance by International Monitoring System hydrophones is at best limited. Sound originating in this area is either blocked or hindered by the South Georgia, South Sandwich Islands and the associated seafloor ridge system, making the region a potential hydroacoustic blind spot. To investigate the sound propagation and interferences affected by these landmasses in the vicinity of the Antarctic polar front, an array of autonomous hydrophones (AUHs) was deployed in the Scotia Sea in December 2007. In January 2009, five AUHs were recovered, completing a 13-month-long acoustic monitoring operation. Four of the recovered instruments continuously recorded low-frequency acoustic signals (1?110 Hz) at a sampling rate of 250 Hz, with one instrument sampling at a rate a rate of 1000 Hz (1?440 Hz band-passed). The submerged moorings utilized autonomous crystal oscillator clocks, with small time shifts that average 2 seconds per year. Despite the fact that the high-latitude ocean lacks a deep sound channel, low-frequency sound tends to travel relatively efficiently. Regional seismo-acoustic signals (bottom sources) and episodic tremors from large icebergs (near-surface sources) were utilized as natural sound sources. Surface sound sources, e.g., ice-related events, tend to suffer less transmission loss (TL) and dominate the background noise as a result of surface duct transmission and less interaction with seafloor features. On the other hand, earthquake-generated signals (bottom sources) interact more strongly with the shallow arc, and TL tends to be larger. The RAM PE-code (Collins, 1993a,b) was used to model TL, and the AUH data were used to compare with these modeling results. Both the observational and model results indicate a unique acoustic environment of the Scotia Sea, including the evidences of reflected T-waves by the steep slope of the South Ge, Published in Proceedings of the 2010 Monitoring Research Review - Ground-Based Nuclear Explosion Monitoring Technologies, 21-23 September 2010, Orlando, FL. Volume II. Sponsored by the Air Force Research Laboratory (AFRL) and the National Nuclear Security Administration (NNSA). U.S. Government or Federal Rights License

This research focuses on a kW-level active-b ridge DC-D C converter. Using two hardware prototypes, the study contraste the per formance of the i nverter-b1 idge section of the converter using either sta te-of-the-art Si licon (Si) or Silicon Carbide (SiC) MOSFET s. Innovations in SiC MOSFET technology have facilitated reductions in steady-state switch losses and operation at higher device temper1 tures. By enabling reductions in losses and higher-temperature operation, converter thermal management requirement is dcueased. T hus, SiC devices offer the possibility of increased converter power density. Converter power density is eva luated by meas uring the maximum power throughput of the converter for a given maximum device j unction temperature T he physica l volumes of the two converters are held fixed so that throughput power will represent a means of directly quant1 fying power densi ty. Tn this paper, the design of the converter is detailed, including gate drivers and snubber circuitry, and testing resu lts are presented., The original document contains color images.

Our long-term scientific goals are to understand the dynamics and identify mechanisms of small-scale processes--i.e., internal tides, inertial waves, nonlinear internal waves (NLIWs), and turbulence mixing--in the ocean and thereby help develop improved parameterizations of mixing for ocean models. Mixing within the stratified ocean is a particular focus as the complex interplay of internal waves from a variety of sources and turbulence makes this a current locus of uncertainty. For this study, our focus is on small-scale processes (NLIWs and inertial waves), internal tides, and cold-water intrusions generated as the Kuroshio and barotropic tides interact with the continental shelf of the East China Sea (ECS) and with one prominent submarine ridge (I-Lan Ridge). These small-scale processes modulate the temporal, horizontal, and vertical spatial structures of water properties in the ocean, and therefore may significantly modify oceanic acoustics and introduce uncertainty to sonar performance and acoustic propagation. Our ultimate goal is to collaborate with acousticians to identify oceanic processes that alter acoustic properties. The properties, mechanisms, and dynamics of these oceanic processes will help quantify and assess uncertainty in acoustic prediction.

The long-term goal of this project is to predict the generation of internal waves over the ridges in the Luzon Strait and wave propagation across the northern South China Sea. The objective of this study is to provide a description of internal wave/tide propagation from the Luzon Strait to the edge of the continental shelf off China. Three issues are to be studied: 1) the relationship between the internal waves and the barotropic tides in the Luzon Strait, 2) temporal and spatial variations of internal wave properties during propagation across the deep basin of the northern South China Sea, and 3) wave transmission across the continental margin.

Objectives are: 1) To determine the feedbacks between waves, tidal fluxes and tidal channels in muddy coastlines 2) To link the geotechnical properties of sediment substrates to the spatial and hydrodynamic characteristics of tidal channels 3) To develop new morphological indicators of tidal flat morphodynamics that can be easily derived from remote sensing images. To link these indicators to mechanical properties of tidal flat substrates 4) To compare the results of the MURI project "Mechanisms of Fluid Mud Interactions under Waves" to wave measurements at the shoreline. 5) To integrate high resolution hydrodynamic measurements within ongoing research activities at the Willapa Bay "Tidal Flats" DRI location., FY10 Annual Reports of S & T efforts sponsored by the Ocean Battlespace Sensing S & T Department of the Office of Naval Research. The original document contains color images.

A 3-dimensional nonhydrostatic numerical model is used to study the generation of internal waves by the barotropic tidal flow over a steep two-dimensional ridge in an ocean with strong upper-ocean stratification. The process is examined by varying topographic width, amplitude of the barotropic tide and stratification at three ridge heights. The results show that a large amount of energy is converted from the barotropic tide to the baroclinic wave when the slope parameter, defined as the ratio of the maximum ridge slope to the maximum wave slope, is greater than. The energy flux of internal waves can be normalized by the vertical integral of the buoyancy frequency over the ridge depths and the kinetic energy of the barotropic tides in the water column. A relationship between the normalized energy flux and the slope parameter is derived. The normalized energy flux reaches a constant value independent of the slope parameter when the slope parameter is greater than 1.5. In the Luzon Strait, the strength of the shallow thermocline and the location of the Kuroshio front could affect generation of internal solitary waves in the northern South China Sea., Published in Deep Sea Research I, v57 p1521-1531, 2010. Work no. 73-9358-09-5

Ridge-buckle defects in cold rolled thin strip originate from the formation of ridges in hot rolled coil and corresponding ridges left in the strip following annealing, cold rolling and tempering. A numerical solution was developed to calculate three-dimensional stress distribution in a wound coil built up wrap-by-wrap and subsequent flatness change in the uncoiled product. The model takes into account both nonlinear compressible characteristic of interwrap layer and uneven strip profile, especially ridges, on the stress evolution during the coiling process. The sensitivity of ridge-buckle defects in cold rolled thin strip to ridges in hot rolled coil profile has been investigated in details. The results show that the ridge-buckle defects in tin plate are much dependent on the height, width and location of ridges in hot coil profile. The permissible tolerance of ridges in hot rolled coil, below which does not produce the ridge-buckle defects in subsequent cold rolling of thin strip, are recommended for different steel grades.

Met drempels tussen de aardappelruggen kan je afspoeling en erosie tegengaan. Dat tonen proeven van het Waalse onderzoekscentrum CRA-W aan.

We are investigating the potential correlation between whale tracks, enhanced zooplankton concentrations and hydrothermal vents above the Juan de Fuca Ridge. Our goal is to understand the influences of globally distributed hydrothermal plumes on the trophic ecology of the deep ocean., Prepared in cooperation with Institute of Ocean SciencesO, Sidney, British Columbia. Code 1 only. The original document contains color images.

Our long-term scientific goals are to understand the dynamics and identify mechanisms of small-scale processes--i.e., internal tides, inertial waves, nonlinear internal waves (NLIWs), and turbulence mixing--in the ocean and thereby help develop improved parameterizations of mixing for ocean models. Mixing within the stratified ocean is a particular focus as the complex interplay of internal waves from a variety of sources and turbulence makes this a current locus of uncertainty. For this study, our focus is on small-scale processes (NLIWs and inertial waves), internal tides, and cold-water intrusions generated as the Kuroshio and barotropic tides interact with the continental shelf of the East China Sea (ECS) and with one prominent submarine ridge (I-Lan Ridge). These small-scale processes modulate the temporal, horizontal and vertical spatial structures of water properties in the ocean, and therefore may significantly modify oceanic acoustics and introduce uncertainty to sonar performance and acoustic propagation. Our ultimate goal is to collaborate with acousticians to identify oceanic processes that alter acoustic properties. The properties, mechanisms, and dynamics of these oceanic processes will help quantify and assess uncertainty in acoustic prediction.

Paper is subjected to stress relaxation during storage in reels. Ridges in the paper reel subject the paper in the ridge to a higher strain than the paper adjacent to the ridge. The strain difference can become a permanent strain difference, resulting in a baggy web after unwinding. Researchers used a geometrical model based on stress relaxation test results to determine when the bagginess is substantial enough to cause problems. The results showed that runnability problems will appear if the ridge is about 1–2 mm high. This applies for a reel with a diameter of 1.2–1.8 m stored for 1 week.

Bij dubbellucht in ruggenteelt is een grotere doorlaat tussen de cultuurwielen nodig dan bij volveldsteelten. In 2006 introduceerde De Hoeve Banden hiervoor een hydraulisch verstelbare constructie, de Forrez Hydrovarial. Vooral het snel en eenvoudig kunnen wisselen van spoorbreedte ervaren gebruikers als het grote pluspunt

Ongoing advances in laboratory experimental techniques have greatly enhanced the ability to obtained detailed spatiotemporal data for internal waves in challenging regimes. The long-term goal of this research is to use the latest experimental techniques to investigate internal wave dynamics relevant to the Luzon Strait in a custom configured wave tank; and to integrate these results with data obtained from numerical simulations, theory and field studies. The principal focus is to determine the generation mechanism for large amplitude solitary waves originating from the Luzon Strait, which is presently undetermined., The original document contains color images.

The remote area of the Atlantic Ocean near the Antarctic Peninsula and the South Scotia Sea is a region where acoustic surveillance by International Monitoring System (IMS) hydrophones is at best limited. Sound originating in this area is either blocked or hindered by the South Georgia Islands (SGI) and the associated seafloor ridge system, making the region a potential hydroacoustic blind spot for IMS stations. In the spring of 2008, we successfully completed the deployment of a hydrophone array consisting of six autonomous underwater hydrophones (AUHs) in the Scotia Sea area. The array configuration is optimum to study sound propagation through the Antarctic Convergence Zone (ACZ), as well as acoustic blockage and reflection caused by islands and associated seafloor topography. Regional seismo-acoustic signals and episodic harmonic tremor from large icebergs will be utilized as natural sound sources., Published in the Proceedings of the 30th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, 23-25 Sep 2008, Portsmouth, VA sponsored by the National Nuclear Security Administration (NNSA) and the Air Force Research Laboratory (AFRL). The original document contains color images.

We are investigating the potential correlation between whale tracks, enhanced zooplankton concentrations and hydrothermal vents above the Juan de Fuca Ridge with the long-term goal of understanding such correlations in terms of the influences of globally distributed hydrothermal plumes on the trophic ecology of the deep ocean. We are conducting a retrospective study using existing seismic and bio-acoustical data sets from the Juan de Fuca Ridge with the following four objectives: 1. Implementing an automatic algorithm to track fin and blue whales using data from a small-scale seafloor seismic network. 2. Tracking vocalizing fin and blue whales above the Endeavour segment over a 3-year interval from 2003-2006 in order to determine whether they are preferentially found above the hydrothermal vent fields where the bio-acoustical data show that the zooplankton concentrations are higher at all depths. 3. Analyzing a total of 60 net tow samples from the Endeavour Segment from 1995 and 1996 and combining these with 119 previously analyzed net-tow samples from 1991-1994 to refine our understanding of the variations of zooplankton concentrations at different depths with distance from the vent fields. Using the simultaneous acoustic backscatter and net tow data to calibrate the acoustic observations so that we can make use extensive acoustic Doppler current profiler (ADCP) data sets that already exist for the region (as well as ADCP data that may be collected in the future) to estimate zooplankton concentrations. The central portion of the Endeavour Segment of the Juan de Fuca Ridge (129 deg. W, 48 deg. N) hosts several large hydrothermal vent fields and has been extensively studied by marine geoscientists for over two decades. It is presently one of three sites at which NSF's RIDGE2000 program is conducting Integrated Studies.

The web tension profile can detect potentially baggy areas even when the web tension is high enough to mask them. Web tension profiles and web length profile were measured with a new non-contact measuring unit, where the web flows on air cushions to avoid disturbing the web path and tension. Bagginess was produced by winding plastic film of thickness 7 microns into paper rolls. Three different paper grades, MG paper and liner with two different grammages, were tested. There was a decrease in web tension in the position where the plastic had been rolled in, i.e. the ridge had become a baggy lane. The lane was most baggy closest to the roll core, Baggy paper webs / Slappa och spända stråk i pappersbanor