scholarly journals 2D OVERTOPPING AND IMPACT EXPERIMENTS IN SHALLOW FORESHORE CONDITIONS

2018 ◽  
pp. 67
Author(s):  
Vincent Gruwez ◽  
Ine Vandebeek ◽  
Dogan Kisacik ◽  
Maximilian Streicher ◽  
Corrado Altomare ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Surf Zone ◽  
High Spatial Resolution ◽  
Wave Structure ◽  
High Energy ◽  
Water Levels ◽  
Wave Transformation ◽  
Wave Overtopping ◽  
Typical Situation ◽  
Wave Flume

This paper introduces the 2D experiments conducted for the CREST project in the wave flume of Ghent University. The experiments focus on wave interactions with low-crested sea dikes fronted by a shallow foreshore and mildly to steeply sloping beaches, which is a very typical situation along the Belgian coast. Foreshore slopes of 1/20, 1/35, 1/50 and 1/80 were tested for a range of low to high energy wave conditions, a variation in wave steepness and two water levels. The main goal was to obtain a dataset in which the effects of the infragravity waves on the wave-structure interactions (i.e. wave overtopping and impact forces) can be studied. The tests included high spatial resolution surface elevation measurement tests, which is new for beaches including a dike in the inner surf zone. From the first results it became clear that the foreshore slope influences the wave transformation up to the dike toe. The influence is apparent comparing to existing (semi-) empirical models for prediction of the spectral wave period at the dike toe and wave overtopping at the dike crest. The high spatial resolution data show a steep increase in infragravity significant wave height in the very shallow area in front of the dike.

scholarly journals Environmental controls on surf zone injuries on high-energy beaches

2019 ◽  
Vol 19 (10) ◽  
pp. 2183-2205 ◽  
Author(s):  
Bruno Castelle ◽  
Tim Scott ◽  
Rob Brander ◽  
Jak McCarroll ◽  
Arthur Robinet ◽  
...  
Keyword(s):  
Wave Height ◽  
Surf Zone ◽  
High Tide ◽  
High Energy ◽  
Water Levels ◽  
Small Scale ◽  
Beach Morphology ◽  
Environmental Controls ◽  
Flow Activity ◽  
Incident Waves

Abstract. The two primary causes of surf zone injuries (SZIs) worldwide, including fatal drowning and severe spinal injuries, are rip currents (rips) and shore-break waves. SZIs also result from surfing and bodyboarding activity. In this paper we address the primary environmental controls on SZIs along the high-energy meso–macro-tidal surf beach coast of southwestern France. A total of 2523 SZIs recorded by lifeguards over 186 sample days during the summers of 2007, 2009 and 2015 were combined with measured and/or hindcast weather, wave, tide, and beach morphology data. All SZIs occurred disproportionately on warm sunny days with low wind, likely because of increased beachgoer numbers and hazard exposure. Relationships were strongest for shore-break- and rip-related SZIs and weakest for surfing-related SZIs, the latter being also unaffected by tidal stage or range. Therefore, the analysis focused on bathers. More shore-break-related SZIs occur during shore-normal incident waves with average to below-average wave height (significant wave height, Hs = 0.75–1.5 m) and around higher water levels and large tide ranges when waves break on the steepest section of the beach. In contrast, more rip-related drownings occur near neap low tide, coinciding with maximised channel rip flow activity, under shore-normal incident waves with Hs >1.25 m and mean wave periods longer than 5 s. Additional drowning incidents occurred at spring high tide, presumably due to small-scale swash rips. The composite wave and tide parameters proposed by Scott et al. (2014) are key controlling factors determining SZI occurrence, although the risk ranges are not necessarily transferable to all sites. Summer beach and surf zone morphology is interannually highly variable, which is critical to SZI patterns. The upper beach slope can vary from 0.06 to 0.18 between summers, resulting in low and high shore-break-related SZIs, respectively. Summers with coast-wide highly (weakly) developed rip channels also result in widespread (scarce) rip-related drowning incidents. With life risk defined in terms of the number of people exposed to life threatening hazards at a beach, the ability of morphodynamic models to simulate primary beach morphology characteristics a few weeks or months in advance is therefore of paramount importance for predicting the primary surf zone life risks along this coast.

Recent experiments with nuclear emulsions

1964 ◽  
Vol 278 (1374) ◽  
pp. 350-369 ◽  
Keyword(s):  
Spatial Resolution ◽  
Nuclear Emulsion ◽  
High Energy Physics ◽  
High Spatial Resolution ◽  
Bubble Chamber ◽  
High Energy ◽  
Emulsion Technique ◽  
Decay Modes ◽  
Automatic Methods ◽  
The Many

It is unnecessary to stress the many significant contributions made during the past 20 years to nuclear and high-energy physics by means of the nuclear emulsion technique. One needs only to recall the new particles and decay modes that have been first observed with it. With the development of other powerful techniques, however, such as the spark-chamber and bubble-chamber, readily adaptable to automatic methods of analysis and data handling, nuclear emulsion has inevitably tended to fall into the position of a supplementary method. Nevertheless, there are still important experiments for which it is the most convenient, indeed in some cases the only, technique available, and this paper will discuss such experiments, either recently carried out or proposed for the future, using beams of particles from high-energy accelerators. Nuclear emulsion possesses one most significant advantage over all other tech­niques, namely, the extraordinarily high spatial resolution of which it is capable. Other techniques can resolve events separated by tenths of millimetres. Nuclear emulsion can resolve events separated by tenths of micrometres. This high spatial resolution has made possible the measurement of the lifetime of the π 0 -meson (ca.10 -16 s) and is the basis of our confidence that there are no other commonly occurring unstable particles with lifetimes in the range 10 -11 to 10 -16 s. Most of the experiments described in this paper are particularly suited to the nuclear emulsion technique because they make use of this characteristic feature.

scholarly journals Environmental controls on surf zone injuries on high-energy beaches

2019 ◽  
Author(s):  
Bruno Castelle ◽  
Tim Scott ◽  
Rob Brander ◽  
Jak McCarroll ◽  
Arthur Robinet ◽  
...  
Keyword(s):  
Wave Height ◽  
Surf Zone ◽  
High Tide ◽  
High Energy ◽  
Water Levels ◽  
Small Scale ◽  
Beach Morphology ◽  
Environmental Controls ◽  
Flow Activity ◽  
Incident Waves

Abstract. The two primary causes of surf zone injuries (SZIs) worldwide, including fatal drowning and severe spinal injuries, are rip currents (rips) and shore-break waves. SZIs also result from surfing and body boarding activity. In this paper we address the primary environmental controls on SZIs along the high-energy meso-macrotidal surf beach coast of SW France. A total of 2523 SZIs recorded by lifeguards over 186 sample days during the summers of 2007, 2009 and 2015 were combined with measured and/or hindcast weather, wave, tide and beach morphology data. All SZIs occurred disproportionately on warm sunny days with low wind likely because of increased beachgoer numbers and hazard exposure. Relationships were strongest for shore break and rip related SZIs and weakest for surfing related SZIs, the latter being also unaffected by tidal stage or range. Therefore the analysis focussed on bathers. Shore-break related SZIs disproportionately occur during shore-normal incident waves with average to below-average wave height (significant wave height Hs = 0.75–1.5 m) and around higher water levels and large tide range when waves break on the steepest section of the beach. In contrast, rip related drownings occur disproportionally near neap low tide, coinciding with maximized channel rip flow activity, under shore-normal incident waves with Hs > 1.25 m and periods mean wave period longer than 5 s. Additional drowning incidents occurred at spring high tide, presumably due to small-scale swash rips. The composite wave and tide parameters proposed by Scott et al. (2014) are key controlling factors determining SZI occurrence, although the risk ranges are not necessarily transferable to all sites. Summer beach and surf zone morphology is highly interannually variable, which is critical to SZI patterns. The upper beach slope can vary from 0.06 to 0.18 between summers, resulting in low and high shore-break related SZIs, respectively. Summers with coast-wide highly (weakly) developed rip channels also result in widespread (scarce) rip related drowning incidents. With life risk defined in terms of the number of people exposed to life threatening hazards at a beach, the ability of morphodynamic models to simulate primary beach morphology characteristics a few weeks/months in advance is therefore of paramount importance to predict the primary surf-zone life risks along this coast.

Effect of Coating with Hydroxyapatite on the Bonding of Bone to Implant

2012 ◽  
Vol 706-709 ◽  
pp. 1661-1666
Author(s):  
Abdelilah Benmarouane ◽  
Pierre Millet ◽  
Thomas Buslaps ◽  
Alain Lodini ◽  
Veijo Honkimäki
Keyword(s):  
Synchrotron Radiation ◽  
Spatial Resolution ◽  
Orthopaedic Surgery ◽  
High Spatial Resolution ◽  
High Energy ◽  
Direct Connection ◽  
X Ray Diffraction ◽  
X Ray ◽  
Natural Bone ◽  
Non Destructive

The aim of the present study was to study the interface implant-bone by synchrotron radiation, the implant has two faces the first one coated with hydroxyapatite and the second uncoated. In orthopaedic surgery, Titanium (Ti-Al-4V) implants are currently coated with hydroxyapatite (HAp), Ca10(PO4)6(OH)2, in order to obtain a stable and functional direct connection between the bone and the implant. At the implant-bone interface, the new bone reconstituted after two months of implantation must have the same properties like the natural bone in order to accept the implant. Therefore we studied the texture of the reconstituted bone crystals at the interface applying non destructive x-ray diffraction. The required high spatial resolution was achieved utilizing high-energy synchrotron radiation on ID15 at ESRF in Grenoble, France.

Macro and Micro Full Field X-Ray Fluorescence with an X-Ray Pinhole Camera Presenting High Energy and High Spatial Resolution

2014 ◽  
Vol 86 (21) ◽  
pp. 10892-10899 ◽  
Author(s):  
Francesco Paolo Romano ◽  
Claudia Caliri ◽  
Luigi Cosentino ◽  
Santo Gammino ◽  
Lorenzo Giuntini ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
High Spatial Resolution ◽  
High Energy ◽  
Pinhole Camera ◽  
Full Field ◽  
X Ray

scholarly journals Instrumentation for the Measurement of High Energy Phenomena on NASA Spacecraft

1971 ◽  
Vol 41 ◽  
pp. 134-134
Author(s):  
Albert G. Opp ◽  
Nancy G. Roman
Keyword(s):  
Spatial Resolution ◽  
Spectral Distribution ◽  
High Spatial Resolution ◽  
High Sensitivity ◽  
High Energy ◽  
Temporal Variations ◽  
X Ray ◽  
Sky Survey ◽  
Beryllium Window ◽  
Proportional Counters

High energy astrophysical observations supported by the National Aeronautics and Space Administration will be conducted primarily from the Small Astronomy Satellites (SAS) and the High Energy Astronomy Observatories (HEAO). At the present time, three Small Astronomy Satellites have been approved for flight. The first (SAS A) will carry a set of collimated proportional counters to conduct a high sensitivity, high spatial resolution, all sky survey for X-ray sources, to search for temporal variations in the source intensity, and to measure the spectral distribution of sources in the energy range 1 to 20 keV. The spacecraft will carry two collimator systems of 1 by 10 deg and 10 by 10 deg fullwidth. The proportional counters are gas-filled beryllium window tubes. SAS A is planned for launch in late 1970.

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