scholarly journals LONG TERM MORPHOLOGICAL MODELLING

2011 ◽  
Vol 1 (32) ◽  
pp. 64
Author(s):  
Sten Esbjørn Kristensen ◽  
Rolf Deigaard ◽  
Martin Anders Taaning ◽  
Jørgen Fredsøe ◽  
Nils Drønen ◽  
...  
Keyword(s):  
Time Scale ◽  
Surf Zone ◽  
Coastal Structures ◽  
Model Concept ◽  
General Applicability ◽  
Shoreline Evolution ◽  
Realistic Representation ◽  
Morphological Modelling ◽  
Constant Shape

A morphological modelling concept for long term nearshore morphology is proposed and examples of its application are presented and discussed. The model concept combines parameterised representations of the cross-shore morphology, with a 2DH area model for waves, currents and sediment transport in the surf zone. Two parameterization schemes are tested for two different morphological phenomena: 1) Shoreline changes due to the presence of coastal structures and 2) alongshore migration of a nearshore nourishment and a bar by-passing a harbour. In the case of the shoreline evolution calculations, a concept often used in one-line modelling of cross-shore shifting of an otherwise constant shape cross-shore profile is applied for the case of a groyne and a detached breakwater. In the case of alongshore bar/nourishment migration an alternative parameterization is adopted. All examples are presented, analysed and discussed with respect to the question of realistic representation, time scale and general applicability of the model concept.

scholarly journals SHOREWARD SAND TRANSPORT OUTSIDE THE SURFZONE, NORTHERN GOLD COAST, AUSTRALIA

2012 ◽  
Vol 1 (33) ◽  
pp. 26 ◽  
Author(s):  
Dean Patterson
Keyword(s):  
Surf Zone ◽  
River Mouth ◽  
Transport Processes ◽  
Gold Coast ◽  
Sand Transport ◽  
Large Wave ◽  
Wave Flume ◽  
Shoreline Evolution ◽  
The One

To date, no suitable theoretical basis has been derived to predict with reliable accuracy the shoreward sand transport under waves in the deeper water outside the surf zone. This is important for understanding the rate of recovery of beaches after major storm erosion and, in some circumstances, to quantify net shoreward supply of sand to the shoreline from the active lower shore-face below the depth of storm erosion bar development. Even a relatively low rate of long term shoreward net supply may contribute to shoreline stability where it offsets a gradient in the longshore sand transport that would otherwise lead to recession. This paper outlines the results of analysis of a 41 year dataset of beach and nearshore profile surveys to quantify annual average rates of shoreward net sand transport in 6-20m water in an area where the profiles are not in equilibrium due to the existence of a residual river mouth ebb delta bar lobe. Additionally, an empirical adaptation of the sheet flow relationship of Ribberink and Al-Salem (1990) to provide for the effects of ripples has been derived from large wave flume data and correlates well with the measured Gold Coast transport rates. These have been applied to a new coastline modelling system developed as part of research into the long term evolution of Australia’s central east coast region in response to sea level change and longshore sand transport processes, which combines the one-line concept of shoreline profile translation within the zone of littoral sand transport with cross-shore profile evolution across the deeper shore-face profile below that zone. It demonstrates the importance of providing for both the shoreward supply from the continental shelf and the varying profile response time-scale across the shore-face in predicting shoreline evolution.

The long-term instability of the new generation hydrogen masers

2020 ◽  
pp. 35-38
Author(s):  
S.I. Donchenko ◽  
I.Y. Blinov ◽  
I.B. Norets ◽  
Y.F. Smirnov ◽  
A.A. Belyaev ◽  
...  
Keyword(s):  
Time Scale ◽  
Frequency Difference ◽  
Clock Frequency ◽  
Quantum Frequency ◽  
Frequency Standards ◽  
Quantum Frequency Standards ◽  
New Generation ◽  
Atomic Time

The latest changes in the algorithm for the formation of the international atomic time scale TAI are reported in terms of estimating the weights of the clocks involved in the formation of TAI. Studies of the characteristics of the long-term instability of new-generation hydrogen masers based on processing the results of the clock frequency difference with respect to TAI are performed. It has been confirmed that at present, new-generation hydrogen masers show significantly less long-term instability in comparison with quantum frequency standards ofsimilar and other types.

scholarly journals Ensemble Pulsar Time Study by Pulsar Timing Observations

2004 ◽  
Vol 218 ◽  
pp. 439-440
Author(s):  
Tinggao Yang ◽  
Guangren Ni
Keyword(s):  
Time Scale ◽  
Wavelet Decomposition ◽  
Time Study ◽  
Millisecond Pulsar ◽  
Millisecond Pulsars ◽  
Pulsar Time ◽  
Pulsar Timing ◽  
Timing Data ◽  
Gravitational Wave Background

Long term timing of multiple millisecond pulsars can contribute to the study of an ensemble pulsar time scale PTens. A wavelet decomposition algorithm (WDA) was applied to define a PTens using the available millisecond pulsar timing datA. The PTens obtained from WDA is more stable than those resulting from other algorithms. The Chinese 50 m radio telescope is specially designed for PTens study and detection of gravitational wave background via millisecond pulsars timing observations. A scheme for multiple millisecond pulsar timing and ensemble pulsar time study is discussed in some detail.

scholarly journals The Rate of Information Transfer of Naturalistic Stimulation by Graded Potentials

2003 ◽  
Vol 122 (2) ◽  
pp. 191-206 ◽  
Author(s):  
Mikko Juusola ◽  
Gonzalo G. de Polavieja
Keyword(s):  
Time Scale ◽  
Information Transfer ◽  
Bright Light ◽  
Scale Structure ◽  
Finite Duration ◽  
Adaptation Mechanisms ◽  
Short And Long Term ◽  
Signaling Strategies

We present a method to measure the rate of information transfer for any continuous signals of finite duration without assumptions. After testing the method with simulated responses, we measure the encoding performance of Calliphora photoreceptors. We find that especially for naturalistic stimulation the responses are nonlinear and noise is nonadditive, and show that adaptation mechanisms affect signal and noise differentially depending on the time scale, structure, and speed of the stimulus. Different signaling strategies for short- and long-term and dim and bright light are found for this graded system when stimulated with naturalistic light changes.

scholarly journals Has erosion globally increased? Long-term erosion rates as a function of climate derived from the impact crater inventory

2018 ◽  
Author(s):  
Stefan Hergarten ◽  
Thomas Kenkmann
Keyword(s):  
Time Scale ◽  
Impact Crater ◽  
Regional Effect ◽  
Tropical Zone ◽  
Erosion Rates ◽  
Continental Scale ◽  
River Loads ◽  
The Impact

Abstract. Worldwide erosion rates seem to have increased strongly since the beginning of the Quaternary, but there is still discussion about the role of glaciation as a potential driver and even whether the increase is real at all or an artefact due to losses in the long-term sedimentary record. In this study we derive estimates of average erosion rates on the time scale of some tens of million years from the terrestrial impact crater inventory. This approach is completely independent from all other methods to infer erosion rates such as river loads, preserved sediments, cosmogenic nuclides and thermochronometry. Our approach yields average erosion rates as a function of present-day topography and climate. The results confirm that topography accounts for the main part of the huge variation of erosion on Earth, but also identifies a significant systematic dependence on climate in contrast to several previous studies. We found a fivefold increase in erosional efficacy from the cold regimes to the tropical zone and that temperate and arid climates are very similar in this context. Combining our results to a worldwide mean erosion rate we found that erosion rates on the time scale of some tens of million years are at least as high as present-day rates and suggest that glaciation has a rather regional effect with a limited impact at the continental scale.

Interferometric long-term stabilization of a delay line: a tool for pump–probe photoelectron–photoion-coincidence spectroscopy on the attosecond time scale

2008 ◽  
Vol 91 (2) ◽  
pp. 287-293 ◽  
Author(s):  
F.M. Böttcher ◽  
B. Manschwetus ◽  
H. Rottke ◽  
N. Zhavoronkov ◽  
Z. Ansari ◽  
...  
Keyword(s):  
Time Scale ◽  
Delay Line ◽  
Pump Probe ◽  
Coincidence Spectroscopy

scholarly journals Decision-making in Russia’s Foreign Policy Modelling Russia’s Decision-Making with reference to Ukraine and Moldova (2004-2018)

2021 ◽  
Vol 9 (6) ◽  
pp. 42
Author(s):  
Kristine Zaidi
Keyword(s):  
Decision Making ◽  
Foreign Policy ◽  
Academic Research ◽  
Theory Development ◽  
Policy Decision ◽  
Actor Model ◽  
General Applicability ◽  
Proposed Model ◽  
Policy Decision Making

There is a substantial body of literature on Russian foreign policy; however, the decision-making aspect remains comparatively less explored. The ambition of this research developed in two directions; on a practical level, it contributes to knowledge on Russia’s foreign policy decision-making and, on a conceptual plane, to scholarship by way of theory development, underpinning academic research on decision-making in foreign policy. Russia’s decision-making was first viewed through the prism of the Rational Actor Model and Incrementalism; however, their utility was found to be limited. Blended models also did not figure strongly. Through the prism of author’s proposed model of Strategic Incrementalism and its principles, this research demonstrates that Russia’s foreign-policy decision-making is far from a case of ‘muddling through,’ it retains a long-term purposefulness, and that its incremental decisions are guided by farsightedness. The simplicity and general applicability of the model potentially suggest its broader utility.

The Long-Term Stability of Becquerelite

1994 ◽  
Vol 353 ◽  
Author(s):  
R.J. Finch ◽  
J. Suksi ◽  
K. Rasilainen ◽  
R.C. Ewing
Keyword(s):  
Ground Water ◽  
Time Scale ◽  
Solubility Product ◽  
Term Stability ◽  
Long Term Stability ◽  
Uranium Series ◽  
Lower Solubility ◽  
Geologic Disposal ◽  
Petrographic Analyses

AbstractUranium-series disequilibria data, in conjunction with petrographic analyses, indicate that the uranyl oxide hydrate becquerelite can persist for hundreds of thousands of years, possibly longer. Becquerelite probably forms continuously as ground water compositions permit and is resistant to U leaching by ground water. On the time scale of interest for the geologic disposal of spent UO2 nuclear fuel, becquerelite is a long-lived sink for uranium in oxidizing, U and Ca-bearing ground waters. Such long-term stability also supports recent solubility experiments that indicate natural becquerelite has a lower solubility product than that determined for synthetic becquerelites.

scholarly journals The rise and fall of Anopheles arabiensis (Diptera: Culicidae) in a Tanzanian village

1995 ◽  
Vol 85 (1) ◽  
pp. 37-44 ◽  
Author(s):  
J.D. Charlwood ◽  
J. Kihonda ◽  
S. Sama ◽  
P.F. Billingsley ◽  
H. Hadji ◽  
...  
Keyword(s):  
Life Cycle ◽  
Survival Rate ◽  
Anopheles Arabiensis ◽  
Light Trapping ◽  
Population Decline ◽  
Malaria Vectors ◽  
General Applicability ◽  
Dry Spell ◽  
The Village

AbstractThe continual recruitment of new individuals makes it difficult to study both the survival of multivoltine mosquitoes, and the size of the infectious reservoir in narural populations of malaria vectors. During long-term surveillance of a population of Anopheles gambiae Giles sensu lato in a Tanzanian village by daily light trapping, a temporary dry spell resulted in the cessation of recruitment for a period of 33 days, and a decline in numbers of A. arabiensis Patton caught from over 2000 to less than 10 in a sentinel house. Traps placed elsewhere in the village indicated similar proportionate declines although numbers caught varied according to location. A survival rate of 83% per day was estimated from the rate of population decline. Survival was unrelated to the size of the mosquitoes. The infectious reservoir (the chance of a mosquito acquiring an infection) was estimated to be 2% per feed. The exploitation of fortuitous events which temporarily eliminate a single stage in the life cycle has general applicability in the study of the bionomics of multivoltine insects.

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