Clustered, Stacked and Imbricated Large Coastal Rock Clasts on Ludao Island, Southeast Taiwan, and Their Application to Palaeotyphoon Intensity Assessment

This work investigated the characteristics of a boulder field on the exposed south east coast of Ludao Island (Green Island) in southern Taiwan. Although the region regularly experiences seasonal Pacific typhoons, fieldwork on Ludao was prompted following the double-strike of Typhoon Tembin in August 2012, which followed an unusual looping track and was one of the strongest storms to affect the island in recent decades. In Wen Cuen Bay, large limestone and volcanic clasts (103–105 kg) occur both as isolated individuals and also grouped into distinct clusters across the gently-sloping emerged reef platform of Holocene age. Some individuals reach megaclast proportions. Observations revealed limited evidence for the production of new coastal boulders by Typhoon Tembin. However, clustering, stacking and notable imbrication of old large clasts provide evidence for multiple high-energy palaeoevents. Stacking and imbrication are significant depositional features, implying that (partial) lifting by wave transport was responsible. Boulders deposited by Typhoon Tembin suggest that storm produced minimum flow velocities of 3.2–5.1 m/s. This range of minimum flow velocity (MFV) values is lower than the 4.3–13.8 m/s range inferred from the pre-Tembin boulders, which indicates that older storm washovers must have been stronger, judging from their ability to stack and imbricate large clasts. One explanation for high upper values of palaeoevent MFVs is that localized funnelling of water flow through narrow relict channels (inherited spur-and-groove morphology, oriented perpendicular to the modern reef edge) concentrates onshore flow energy into powerful confined jets. Support for this hypothesis is the positioning and train-of-direction of the main imbricated boulder cluster at the landward head of one such feature. Geomorphic controls amplifying wave-driven flow velocities across the emerged Holocene reef mean that a palaeotyphoon origin is sufficient for explaining large clast stacking and imbrication, without the need to invoke a tsunami hypothesis.

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Spectral Decomposition and Sound Source Localization of Highly Disturbed Flow through a Severe Arterial Stenosis

Bioengineering ◽

10.3390/bioengineering8030034 ◽

2021 ◽

Vol 8 (3) ◽

pp. 34

Author(s):

Fardin Khalili ◽

Peshala T. Gamage ◽

Amirtahà Taebi ◽

Mark E. Johnson ◽

Randal B. Roberts ◽

...

Keyword(s):

Spectral Decomposition ◽

Pressure Fluctuations ◽

Flow Analysis ◽

High Energy ◽

Arterial Stenosis ◽

Epidermal Surface ◽

Flow Through ◽

Processing Techniques ◽

Proper Orthogonal ◽

Signal Processing Techniques

For the early detection of atherosclerosis, it is imperative to explore the capabilities of new, effective noninvasive diagnosis techniques to significantly reduce the associated treatment costs and mortality rates. In this study, a multifaceted comprehensive approach involving advanced computational fluid dynamics combined with signal processing techniques was exploited to investigate the highly turbulent fluctuating flow through arterial stenosis. The focus was on localizing high-energy mechano-acoustic source potential to transmit to the epidermal surface. The flow analysis results showed the existence of turbulent pressure fluctuations inside the stenosis and in the post-stenotic region. After analyzing the turbulent kinetic energy and pressure fluctuations on the flow centerline and the vessel wall, the point of maximum excitation in the flow was observed around two diameters downstream of the stenosis within the fluctuating zone. It was also found that the concentration of pressure fluctuation closer to the wall was higher inside the stenosis compared to the post-stenotic region. Additionally, the visualization of the most energetic proper orthogonal decomposition (POD) mode and spectral decomposition of the flow indicated that the break frequencies ranged from 80 to 220 Hz and were correlated to the eddies generated within these regions.

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Spectral Decomposition of the Flow and Characterization of the Sound Signals through Stenoses with Different Levels of Severity

Bioengineering ◽

10.3390/bioengineering8030041 ◽

2021 ◽

Vol 8 (3) ◽

pp. 41

Author(s):

Fardin Khalili ◽

Peshala T. Gamage ◽

Amirtahà Taebi ◽

Mark E. Johnson ◽

Randal B. Roberts ◽

...

Keyword(s):

Pressure Fluctuations ◽

High Energy ◽

Sound Sources ◽

Severity Level ◽

Non Invasive ◽

Flow Through ◽

Severity Of The Disease ◽

Proper Orthogonal ◽

Different Levels

Treatments of atherosclerosis depend on the severity of the disease at the diagnosis time. Non-invasive diagnosis techniques, capable of detecting stenosis at early stages, are essential to reduce associated costs and mortality rates. We used computational fluid dynamics and acoustics analysis to extensively investigate the sound sources arising from high-turbulent fluctuating flow through stenosis. The frequency spectral analysis and proper orthogonal decomposition unveiled the frequency contents of the fluctuations for different severities and decomposed the flow into several frequency bandwidths. Results showed that high-intensity turbulent pressure fluctuations appeared inside the stenosis for severities above 70%, concentrated at plaque surface, and immediately in the post-stenotic region. Analysis of these fluctuations with the progression of the stenosis indicated that (a) there was a distinct break frequency for each severity level, ranging from 40 to 230 Hz, (b) acoustic spatial-frequency maps demonstrated the variation of the frequency content with respect to the distance from the stenosis, and (c) high-energy, high-frequency fluctuations existed inside the stenosis only for severe cases. This information can be essential for predicting the severity level of progressive stenosis, comprehending the nature of the sound sources, and determining the location of the stenosis with respect to the point of measurements.

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Cerebral high-energy compounds: changes in anoxia

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1962.202.1.77 ◽

1962 ◽

Vol 202 (1) ◽

pp. 77-79 ◽

Cited By ~ 28

Author(s):

Richard N. Lolley ◽

Frederick E. Samson

Keyword(s):

Ion Exchange ◽

Rat Brain ◽

Adenosine Triphosphate ◽

Energy Flow ◽

Inorganic Phosphate ◽

High Energy ◽

High Energy Phosphate ◽

Guanosine Triphosphate ◽

Inosine Monophosphate ◽

Flow Through

Acid-soluble phosphates of rat brain during anoxia were determined by ion-exchange and chemical procedures. There is a general shift during anoxia of triphosphate nucleotides to monophosphates and a very rapid breakdown of phosphoryl-creatine. However, total phosphate leaving the high-energy phosphate pool is not equal to the changes in inorganic phosphate; inorganic phosphate change is much larger than high-energy phosphate change in early anoxia and much smaller in extended anoxia. The patterns of guanosine triphosphate and uridine triphosphate changes are more complex than adenosine triphosphate changes. Nicotinamideadenine dinucleotide levels are steady until late anoxia, at which time they decrease slightly. Cytidine monophosphate is the only cytidine nucleotide detected. Inosine nucleotide concentrations in control animals were below the limit of the method, but in late anoxia inosine monophosphate appeared. The data show that the energy flow through the phosphates in brain is rapid and involves phosphate compounds other than the acid-soluble nucleotides and phosphoryl-creatine.

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An elutriation apparatus for assessing settleability of combined sewer overflows (CSOs)

Water Science & Technology ◽

10.2166/wst.2006.570 ◽

2006 ◽

Vol 54 (6-7) ◽

pp. 223-230 ◽

Cited By ~ 6

Author(s):

J. Marsalek ◽

B.G. Krishnappan ◽

K. Exall ◽

Q. Rochfort ◽

R.P. Stephens

Keyword(s):

Test Results ◽

Combined Sewer Overflows ◽

Dynamic Conditions ◽

Large Size ◽

Combined Sewer ◽

Flow Through ◽

Settling Column ◽

Further Development ◽

Floc Breakage ◽

Flow Velocities

An elutriation apparatus was proposed for testing the settleability of combined sewer outflows (CSOs) and applied to 12 CSO samples. In this apparatus, solids settling is measured under dynamic conditions created by flow through a series of settling chambers of varying diameters and upward flow velocities. Such a procedure reproduces better turbulent settling in CSO tanks than the conventional settling columns, and facilitates testing coagulant additions under dynamic conditions. Among the limitations, one could name the relatively large size of the apparatus and samples (60 L), and inadequate handling of floatables. Settleability results obtained for the elutriation apparatus and a conventional settling column indicate large inter-event variation in CSO settleability. Under such circumstances, settling tanks need to be designed for “average” conditions and, within some limits, the differences in test results produced by various settleability testing apparatuses and procedures may be acceptable. Further development of the elutriation apparatus is under way, focusing on reducing flow velocities in the tubing connecting settling chambers and reducing the number of settling chambers employed. The first measure would reduce the risk of floc breakage in the connecting tubing and the second one would reduce the required sample size.

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Advantages of beachrock slabs for interpreting high-energy wave transport: Evidence from Ludao Island in south-eastern Taiwan

Geomorphology ◽

10.1016/j.geomorph.2014.09.010 ◽

2015 ◽

Vol 228 ◽

pp. 263-274 ◽

Cited By ~ 17

Author(s):

A.Y. Annie Lau ◽

James P. Terry ◽

Adam D. Switzer ◽

Jeremy Pile

Keyword(s):

High Energy ◽

South Eastern ◽

Wave Transport

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Hydraulic performance of helical-step dropshaft

Water Science & Technology ◽

10.2166/wst.2021.295 ◽

2021 ◽

Author(s):

Weichen Ren ◽

Jianhua Wu ◽

Fei Ma ◽

Shangtuo Qian

Keyword(s):

Energy Dissipation ◽

Pressure Distribution ◽

Cavitation Erosion ◽

Air Entrainment ◽

Flow Regimes ◽

High Energy ◽

Energy Dissipation Rate ◽

Attractive Alternative ◽

Air Concentration ◽

Flow Energy

Abstract Aiming to achieve energy dissipation and prevention of cavitation erosion, a kind of dropshaft in urban drainage systems, called helical-step dropshaft, is introduced in this paper. It dissipates flow energy by means of step geometry and prevent cavitation erosion through air entrainment. To verify its availability, the hydraulic characteristics of the helical-step dropshaft were experimentally investigated, including the flow regimes, the efficiency of energy dissipation, characteristics of air entrainment and pressure distribution. The results demonstrate that, even for a large discharge, flow can be discharged smoothly and steadily, and a high energy-dissipation rate of over 87% is achieved. There are three distinct flow regimes observed in the dropshaft, namely nappe flow, mixed flow and skimming flow. Moreover, there is no less than 1.6% air concentration and a reasonable pressure distribution on the step surface. This study provides an attractive alternative for the design of drop structures.

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Microwave disinfection as a treatment for blackwater from dewatered sludge

Gates Open Research ◽

10.12688/gatesopenres.12801.1 ◽

2018 ◽

Vol 2 ◽

pp. 16

Author(s):

Katelyn L Sellgren ◽

Christopher W Gregory ◽

Ethan J.D. Klem ◽

Jeffrey R. Piascik ◽

Brian R. Stoner

Keyword(s):

Cost Efficiency ◽

Low Cost ◽

High Energy ◽

Microwave Energy ◽

Disposal Site ◽

Thermal Heating ◽

Compact Size ◽

Fecal Sludge ◽

Flow Through ◽

Potential Use

Background: Fast and efficient on-site treatment of blackwater, rejected from the dewatering process, can decrease the costs associated with disposal of fecal sludge removed from pit latrines by reducing the volume of sludge transported to the disposal site.Methods: In this study, we examine the potential use of low cost consumer microwave units for disinfecting pathogen-rich blackwater. Domestic bench top microwave units were modified to allow flow through and re-circulation of blackwater. Energy, throughput, and disinfection characteristics related to microwaves are studied and compared to conventional thermal heating. A custom flow through stack of 5 microwaves was designed and used to examine the feasibility of single pass, high throughput application.Results and Conclusions: The results show microwave energy does not play a role in the disinfection of blackwater. The benefits of a microwave disinfection system are shown to be high energy efficiency, compact size, and cost efficiency.

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Debris flow interaction with structures: challenges to traditional load models

10.5194/egusphere-egu2020-18157 ◽

2020 ◽

Author(s):

Alessandro Leonardi ◽

Andrea Pasqua ◽

Marina Pirulli

Keyword(s):

Debris Flow ◽

Relative Size ◽

Nonlinear Function ◽

Field Measurements ◽

Italian Alps ◽

Load Model ◽

Flow Energy ◽

Load Models ◽

Maintenance Work ◽

Flow Through

Debris flow barriers often feature one or more filter elements, i.e. narrow outlets that induce deposition of the coarsest sediments, while allowing water and fines to filter through. Slit dams and steel nets are examples of this type of barriers. The design of the filter elements must balance the need to trap boulders and to dissipate the flow energy, while keeping maintenance work as low as possible.Filter barriers elude the traditional load model prescribed by guidelines. Under some conditions, the outlets can clog with large boulders. The time necessary for this to happen mainly depends on the relative size between boulder and outlet, and is a nonlinear function of the flow composition. In any case, the main clogging mechanism is the formation of granular arches. These can induce significant load also in directions different from the main direction of the incoming flow.Unless the barrier is specifically designed to withstand this type of load, granular arches, but also prolonged flow through the outlet, can induce deterioration and loss of functionality of the structure. In this work, we estimate these effects employing a combination of discrete- and continuum-based numerical methods. We evaluate the performance of two types of debris-resisting barriers, comparing the results with laboratory measurements and with the outcome of a monitoring campaign on a real barrier located in the Italian alps.&#160;&#160;References:Leonardi, A., Goodwin, G. R., & Pirulli, M. (2019). The force exerted by granular flows on slit dams. Acta Geotechnica, 14(6), 1949&#8211;1963.Leonardi, A., & Pirulli, M. (2020). Analysis of the load exerted by debris flows on filter barriers : Comparison between numerical results and field measurements. Computer & Geotechnics, 118, 103311.

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Energy Dissipation in Culverts by Forced Hydraulic Jump within a Barrel

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198105190400113 ◽

2005 ◽

Vol 1904 (1) ◽

pp. 124-132

Author(s):

Rollin H. Hotchkiss ◽

Emily A. Larson ◽

David M. Admiraal

Keyword(s):

Energy Dissipation ◽

Hydraulic Jump ◽

Design Procedure ◽

High Energy ◽

Easy Access ◽

Flow Energy ◽

Energy Flows ◽

Stilling Basins ◽

Maintenance Activities ◽

Drop Structure

Riprap and concrete stilling basins are often built at culvert outlets to keep high-energy flows from scouring the streambed. Two simple alternatives to large basins are examined: a horizontal apron with an end weir and a drop structure with an end weir. The two designs are intended to reduce the flow energy at the outlet by inducing a hydraulic jump within the culvert barrel without the aid of tailwater. This research examines the jump geometry and the effectiveness of each jump type and proposes a design procedure for practicing engineers. The design procedure is applicable to culverts with approach Froude numbers from 2.6 to 6.0. Both designs are effective in reducing outlet velocity 0.7 to 8.5 ft/s (0.21 to 2.59 m/s), momentum 10% to 48%, and energy 6% to 71%. The design layouts allow easy access for maintenance activities.

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