scholarly journals DISTRIBUTION OF IMPACT INDUCED PRESSURES AT THE FACE OF UNIFORMLY SLOPED SEA DIKES: PRELIMINARY 2D EXPERIMENTAL RESULTS

2012 ◽  
Vol 1 (33) ◽  
pp. 74 ◽  
Author(s):  
Dimitris Stagonas ◽  
Gerald Muller ◽  
Karunya Ramachandran ◽  
Stefan Schimmels ◽  
Alec Dane
Keyword(s):  
Large Scale ◽  
Tactile Sensor ◽  
Breaking Waves ◽  
Horizontal Distribution ◽  
Breaking Wave ◽  
The Face ◽  
The University ◽  
The Impact ◽  
Sea Dikes ◽  
Sea Dike

Although existing knowledge on the vertical distribution of impact pressures on sea-dikes is well established only very little is known with respect to their horizontal distribution. A collaboration developed between the University of Southampton, Uk and FZK, Hannover looks in more detail at the distribution of pressures induced by waves breaking on the face of a sea-dike. For this, 2D large scale experiments with waves breaking on a 1:3 sea dike were conducted but instead of pressure transducers a tactile pressure sensor was used to map the impact pressures. Such sensors were initially used with breaking waves in the University of Southampton and their use for large scale experiments was attempted here for the first time. In the current paper the calibration and application of the tactile sensor for experiments involving up to 1m high and 8sec long waves are initially described. Preliminary results illustrating the simultaneous distribution of impact induced pressures over an area of 426.7x487.7mm are then presented. Based on these pressure maps the vertical and horizontal location of maximum breaking wave induced pressures is also deduced.

scholarly journals Influence of the Spatial Pressure Distribution of Breaking Wave Loading on the Dynamic Response of Wolf Rock Lighthouse

2021 ◽  
Vol 9 (1) ◽  
pp. 55
Author(s):  
Darshana T. Dassanayake ◽  
Alessandro Antonini ◽  
Athanasios Pappas ◽  
Alison Raby ◽  
James Mark William Brownjohn ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Pressure Distribution ◽  
Distinct Element ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Wave Loading ◽  
Wave Impact ◽  
Pressure Distributions ◽  
Impact Area ◽  
The Impact

The survivability analysis of offshore rock lighthouses requires several assumptions of the pressure distribution due to the breaking wave loading (Raby et al. (2019), Antonini et al. (2019). Due to the peculiar bathymetries and topographies of rock pinnacles, there is no dedicated formula to properly quantify the loads induced by the breaking waves on offshore rock lighthouses. Wienke’s formula (Wienke and Oumeraci (2005) was used in this study to estimate the loads, even though it was not derived for breaking waves on offshore rock lighthouses, but rather for the breaking wave loading on offshore monopiles. However, a thorough sensitivity analysis of the effects of the assumed pressure distribution has never been performed. In this paper, by means of the Wolf Rock lighthouse distinct element model, we quantified the influence of the pressure distributions on the dynamic response of the lighthouse structure. Different pressure distributions were tested, while keeping the initial wave impact area and pressure integrated force unchanged, in order to quantify the effect of different pressure distribution patterns. The pressure distributions considered in this paper showed subtle differences in the overall dynamic structure responses; however, pressure distribution #3, based on published experimental data such as Tanimoto et al. (1986) and Zhou et al. (1991) gave the largest displacements. This scenario has a triangular pressure distribution with a peak at the centroid of the impact area, which then linearly decreases to zero at the top and bottom boundaries of the impact area. The azimuthal horizontal distribution was adopted from Wienke and Oumeraci’s work (2005). The main findings of this study will be of interest not only for the assessment of rock lighthouses but also for all the cylindrical structures built on rock pinnacles or rocky coastlines (with steep foreshore slopes) and exposed to harsh breaking wave loading.

scholarly journals Investigating the Impact of EFL Students’ Misuse of Prosodic Features on their Face-to-face Interactions from University Instructors’ Perspectives

2021 ◽  
Vol 5 (1) ◽  
pp. 50-64
Author(s):  
Bahram Sattar Abdulrahman
Keyword(s):  
Kurdistan Region ◽  
Prosodic Features ◽  
Face To Face ◽  
Iraqi Kurdistan ◽  
University Instructors ◽  
The Face ◽  
Efl Students ◽  
The University ◽  
The Impact ◽  
Special Classes

The present study aims at investigating the use of prosodic features by Kurdish EFL undergraduates in their face-to-face interactions inside/outside the classroom from the university instructors’ perspectives. The study hypothesizes that the majority of Kurdish EFL undergraduates are not fully aware of the fact that any misuse of prosodic features would probably affect the emotions, feelings, and attitudes that the face-to-face interaction is intended to convey. Building on an analysis of a questionnaire given to 54 university instructors at 10 Iraqi Kurdistan Region different universities, the study concludes that the majority of problems the students face can be related to the misuse of stress, intonation, and other prosodic features. Therefore, EFL instructors should pay more attention to make students learn how to use prosodic features and enable them to send messages adequately while engaging in face-to-face interactions. This would require special classes about prosodic features so that EFL students can overcome the misuse they have in face-to-face communication. This is inevitable because accuracy and fluency in communication require EFL students to master both features: segmental and suprasegmental. The reason behind this necessity could be attributed to the fact that broken and/or incorrect pronunciation can be considered as one of the most prominent factors behind misunderstandings in communication.

scholarly journals THE STATE'S RESPONSIBILITY IN THE WELFARE OF PEOPLE AND ECONOMIC RECOVERY IN THE FACE OF COVID-19 FROM THE PERSPECTIVE OF LAW AND HUMAN RIGHTS

1970 ◽  
Vol 21 (2) ◽  
pp. 187-198
Author(s):  
Serlika Aprita ◽  
Lilies Anisah
Keyword(s):  
Human Rights ◽  
Best Practices ◽  
Government Regulation ◽  
Large Scale ◽  
Problem Solver ◽  
The World ◽  
The Face ◽  
The Government ◽  
Almost All ◽  
The Impact

The Covid-19 pandemic was taking place in almost all countries around the world. Along with the increasingly vigorous government strategy in tackling the spread of the corona virus that was still endemic until now, the government had started to enforce the Large-Scale Social Restrictions (PSBB) with the signing of Government Regulation (PP) No. 21 of 2020 about PSBB which was considered able to accelerate countermeasures while preventing the spread of corona that was increasingly widespread in Indonesia. The research method used was normative prescriptive. The government put forward the principle of the state as a problem solver. The government minimized the use of region errors as legitimacy to decentralization. The government should facilitated regional best practices in handling the pandemic. Thus, the pandemic can be handled more effectively. The consideration, the region had special needs which were not always accommodated in national policies. The government policy should be able to encourage the birth of regional innovations in handling the pandemic as a form of fulfilling human rights in the field of health. Innovation was useful in getting around the limitations and differences in the context of each region. In principle, decentralization required positive incentives, not penalties. Therefore, incentive-based central policies were more awaited in handling and minimizing the impact of the pandemic.    

scholarly journals The Role of Responsive Leadership in Meeting Customers' Needs during Crises

2022 ◽  
Vol 13 (1) ◽  
pp. 0-0
Keyword(s):  
Large Scale ◽  
Education Institution ◽  
Face To Face ◽  
Leadership Attributes ◽  
Leadership Support ◽  
The Face ◽  
Quantitative Results ◽  
The Impact

This case study conducted to investigate the impact of a responsive leadership approach in meeting customers' needs in a higher education institution in the UAE during the COVID-19 pandemic. For this purpose, a mixed-method model has been used. The data has been collected from a convenient sample working and studying at Al Qasimia University Language Center, in fall 2020. This result indicates that the provided responsive leadership support during COVID-19 was effective and helped in motivating learners and customers to keep learning and making progress greater than what was shown before COVID-19, during the face-to-face teaching and physical assessment. Although the qualitative and quantitative results in this case study revealed a significant impact of responsive leadership approach on customers’ progress, there is still a need to conduct other researches to develop and validate a responsive leadership inventory to facilitate measuring of responsive leadership attributes in a large scale sample and/or population.

scholarly journals Research Progress for Dynamic Effects of Cities on Precipitation: A Review

Atmosphere ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1355
Author(s):  
Caijun Yue ◽  
Zhihui Han ◽  
Wen Gu ◽  
Yuqi Tang ◽  
Xiangyu Ao
Keyword(s):  
Tropical Cyclones ◽  
Large Scale ◽  
Horizontal Distribution ◽  
Research Progress ◽  
Layer By Layer ◽  
Distribution Characteristics ◽  
Dynamic Effects ◽  
Momentum Exchange ◽  
Extreme Precipitation Events ◽  
The Impact

Citization significantly changes original surface properties. City areas can cause surface winds to decrease; furthermore, ground friction can be transferred layer by layer through the momentum exchange of air movement, which affects the air layers above. Precipitation modification by city environments has been an active research area. Under the conditions of high wind speed, the dynamic effects of cities on precipitation are relatively obvious. Generally, the dynamic effects fall into two main categories: (1) for weather systems under weak forcing synoptic backgrounds, such as local convective systems, shorter-lived extreme precipitation events and fronts and city barrier effects can delay the movement of weather systems, directly change the horizontal distribution characteristics and occurrence time for precipitation, change the flow field and structure, cause the bifurcation of weather systems, and change the horizontal distribution characteristics of precipitation; (2) for weather systems under strong forcing synoptic backgrounds, such as extratropical systems (with large-scale moisture transport), monsoon systems, landfalling tropical cyclones, and supercell storms, the impact of the dynamic effects of cities cannot lead to the bifurcation of the weather system, nor can it change the horizontal distribution characteristics of the whole precipitation field, but it can have an impact on the local precipitation intensity and distribution. However, currently, people do not agree on the impact of cities on precipitation, especially regarding tropical cyclones. Hence, we provide a review and provide insights into the dynamic effects of cities on precipitation.

Breaking Wave Impacts on Platform Columns: Stochastic Analysis and DNV Recommended Practice

2010 ◽  
Author(s):  
Gu¨nther F. Clauss ◽  
Sverre K. Haver ◽  
Mareike Strach
Keyword(s):  
Stochastic Analysis ◽  
Force Sensor ◽  
Breaking Waves ◽  
Model Tests ◽  
Force Sensors ◽  
Breaking Wave ◽  
Small Areas ◽  
The Difference ◽  
Dynamic Amplification ◽  
The Impact

To predict the characteristic impact pressure due to breaking waves on platform columns corresponding to an annual exceedence probability of 10−4 model test data with the Sleipner A gravity based structure (GBS) are subjected to a stochastic analysis. The analysis is based on the environmental contour line approach. In addition, the procedure recommended by Det Norske Veritas (DNV) for calculating shock pressures due to breaking waves is used for comparison. Time histories of pressure and wave elevation for the most severe measured impacts show that the measured pressures are induced by breaking waves. However, a difference between the resulting characteristic impact pressures based on the two approaches can be observed: The stochastic analysis results in much higher pressures than the approach recommended by DNV. These findings are supported by the analysis of data that were collected during model tests with the Gjo̸a semi-submersible and the Snorre A tension leg platform (TLP), where the difference between the results was rather large as well. For the semi-submersible and the TLP, one reason for the difference is bias in the fitment of the stochastic model. Furthermore, dynamic amplification effects in the force sensors have to be considered. However, this bias is less significant for the GBS and dynamic amplification effects are not present since different force sensors were used. For all three model tests, an important source for the different impact pressures is the size of the force sensor area, which varies between 2.25m2 and 10.89m2. Large areas may smoothen the pressure whereas small areas are overrating the impact. Further model testing is required to clarify this effect. If the difference is still present, the recommendation of DNV has to be altered to ensure a reliable prediction of the characteristic impact loads.

A CFD Investigation on the Effect of the Air Entrainment in Breaking Wave Impacts on a Mono-Pile

2017 ◽  
Author(s):  
Pietro D. Tomaselli ◽  
Erik Damgaard Christensen
Keyword(s):  
Experimental Investigation ◽  
Circular Cylinder ◽  
Air Entrainment ◽  
Breaking Waves ◽  
Offshore Structures ◽  
Breaking Wave ◽  
Line Force ◽  
Entrainment Process ◽  
The Impact

In impacts of breaking waves on offshore structures, it is still not well-known how the air entrainment phenomenon affects the exerted loads. In this paper, a developed CFD solver capable of simulating the air entrainment process was employed to reproduce an experimental investigation on the impact of a spilling wave against a circular cylinder. The exerted in-line force was computed with and without the inclusion of dispersed bubbles. Results showed that the magnitude of the computed force was affected when the entrainment of bubbles was simulated.

scholarly journals Oil droplets dispersion under a deep-water plunging breaker: Experimental measurements and numerical modeling

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Fangda Cui ◽  
Cosan Daskiran ◽  
Lin Zhao ◽  
Michel C. Boufadel ◽  
Brian Robinson ◽  
...  
Keyword(s):  
Numerical Method ◽  
Deep Water ◽  
Large Scale ◽  
Oil Spills ◽  
Fluid Dynamic ◽  
Breaking Waves ◽  
Balance Model ◽  
Breaking Wave ◽  
Ansys Fluent ◽  
Plunging Breaker

Abstract (1141370) Wave tank experiments were performed to measure the droplets size distribution under the plunging breaking wave. A deep-water plunging breaker of height 20 cm was generated using the dispersive focusing method, and a shadowgraph camera was used to take images of droplets and bubbles of different sizes. For droplets smaller than the 1000 microns, the number-based DSD matched the DS correlation (Delvigne and Sweeney 1988), which gives N(d) ~ d−2.3, but N(d) ~ d−9.7 for diameters larger than 1000 microns. A numerical method was designed to study the oil dispersion under breaking waves by coupling the computational fluid dynamic (CFD) with the Lagrangian particle tracking code (NEMO3D) and population balance model (VDROP). The wave hydrodynamics was reproduced using the Reynolds-averaged Navier Stokes approach within a commercial CFD code ANSYS Fluent. The obtained wave hydrodynamics was then used as inputs for the NEM3D code and VDROP model. The numerical results show reasonable agreement with our experimental observation. The approach adopted to produce the DSD reduces the empiricism of the DS correlation, as the approach uses oil properties and measurable wave properties. The proposed numerical method was ready to be used in other scenarios of oil spills (i.e., oil jets in deep oceans and oil dispersion in riverine systems). It could also be potentially used in large scale forecast and hindcast simulations for oil spill response and research.

scholarly journals Analysis of the Effects of Lockdown on Staff and Students at Universities Using Natural Language Processing Techniques: Case Study of Spain and Colombia

2021 ◽  
Author(s):  
Mario Fernando Jojoa Acosta ◽  
Begonya Garcia-Zapirain ◽  
Marino J. Gonzalez ◽  
Bernardo Perez-Villa ◽  
Elena Urizar ◽  
...  
Keyword(s):  
Natural Language Processing ◽  
Natural Language ◽  
Language Processing ◽  
Large Scale ◽  
Intelligence Models ◽  
Artificial Intelligence Models ◽  
Processing Techniques ◽  
The University ◽  
The Impact ◽  
Support Students

The review of previous works shows this study is the first attempt to analyse the lockdown effect using Natural Language Processing Techniques, particularly sentiment analysis methods applied at large scale. On the other hand, it is also the first of its kind to analyse the impact of COVID 19 on the university community jointly on staff and students and with a multi-country perspective. The main overall findings of this work show that the most often related words were family, anxiety, house and life. On another front, it has also been shown that staff have a slightly less negative perception of the consequences of COVID in their daily life. We have used artificial intelligence models like swivel embedding and the Multilayer Perceptron, as classification algorithms. The performance reached in terms of accuracy metric are 88.8% and 88.5%, for student and staff respectively. The main conclusion of our study is that higher education institutions and policymakers around the world may benefit from these findings while formulating policy recommendations and strategies to support students during this and any future pandemics.

Experimental Investigations of Breaking Wave Impact Forces on a Monopile Substructure for Offshore Wind Turbines Under Regular Breaking Waves

2017 ◽  
Author(s):  
Vipin Chakkurunni Palliyalil ◽  
Panneer Selvam Rajamanickam ◽  
Mayilvahanan Alagan Chella ◽  
Vijaya Kumar Govindasamy
Keyword(s):  
Circular Cylinder ◽  
Wind Turbines ◽  
Breaking Waves ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Breaking Wave ◽  
Wave Impact ◽  
Offshore Wind Turbines ◽  
Impact Forces ◽  
The Impact

The main objective of the paper is to investigate wave impact forces from breaking waves on a monopile substructure for offshore wind turbine in shallow waters. This study examines the load assessment parameters relevant for breaking wave forces on a vertical circular cylinder subjected to breaking waves. Experiments are conducted in a shallow water flume and the wave generation is based on piston type wave maker. The experiments are performed with a vertical circular cylinder with diameter, D = 0.20m which represents a monopile substructure for offshore wind turbines with regular waves of frequencies around 0.8Hz. The experimental setup consists of a 1/10 slope followed by a horizontal bed portion with a water depth of 0.8m. Plunging breaking waves are generated and free surface elevations are measured at different locations along the wave tank from wave paddle to the cylinder in order to find the breaking characteristics. Wave impact pressures are measured on the cylinder at eight different vertical positions along the height of the cylinder under breaking waves for different environmental conditions. The wave impact pressures and wave surface elevations in the vicinity of the cylinder during the impact for three different wave conditions are presented and discussed.

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