scholarly journals RESONANT OSCILLATIONS IN SMALL CRAFT HARBOURS: OBSERVATIONS AND MITIGATION MODELING EXAMPLES FROM ATLANTIC CANADA

2018 ◽  
pp. 62
Author(s):  
Vincent Leys ◽  
Victoria Fernandez ◽  
Danker Kolijn
Keyword(s):  
Case Studies ◽  
Analytical Methods ◽  
Numerical Models ◽  
Long Waves ◽  
Field Observations ◽  
Existing Structures ◽  
Wave Forcing ◽  
Infrastructure Design ◽  
Small Craft ◽  
External Wave

Agitation from swells and long waves can pose serious challenges for harbours, in terms of both infrastructure design and operations. Wave gauge observations from Atlantic Canadian harbours of varying sizes were used to assess how combinations of basin dimensions and external wave forcing may lead to swell agitation, resonance, and scour problems. This paper summarizes how basin resonances were investigated with field observations, analytical methods, and then phase-resolving numerical models. The case studies illustrate how resonance mitigation may require substantial (and sometimes impractical) changes in harbour layout. Swell and scour mitigation may be more readily achieved by modifications or additions to existing structures.

Droughts, floods and freshwater ecosystems: evaluating climate change impacts and developing adaptation strategies

2011 ◽  
Vol 62 (3) ◽  
pp. 223 ◽  
Author(s):  
Allison Aldous ◽  
James Fitzsimons ◽  
Brian Richter ◽  
Leslie Bach
Keyword(s):  
Climate Change ◽  
Case Studies ◽  
Management Practices ◽  
Climate Adaptation ◽  
Numerical Models ◽  
Climate Change Impacts ◽  
Freshwater Ecosystems ◽  
Adaptation Strategies ◽  
South Eastern ◽  
Eastern Australia

Climate change is expected to have significant impacts on hydrologic regimes and freshwater ecosystems, and yet few basins have adequate numerical models to guide the development of freshwater climate adaptation strategies. Such strategies can build on existing freshwater conservation activities, and incorporate predicted climate change impacts. We illustrate this concept with three case studies. In the Upper Klamath Basin of the western USA, a shift in land management practices would buffer this landscape from a declining snowpack. In the Murray–Darling Basin of south-eastern Australia, identifying the requirements of flood-dependent natural values would better inform the delivery of environmental water in response to reduced runoff and less water. In the Savannah Basin of the south-eastern USA, dam managers are considering technological and engineering upgrades in response to more severe floods and droughts, which would also improve the implementation of recommended environmental flows. Even though the three case studies are in different landscapes, they all contain significant freshwater biodiversity values. These values are threatened by water allocation problems that will be exacerbated by climate change, and yet all provide opportunities for the development of effective climate adaptation strategies.

scholarly journals Recent advances in understanding Antarctic climate evolution

2008 ◽  
Vol 20 (4) ◽  
pp. 313-325 ◽  
Author(s):  
Martin J. Siegert ◽  
Peter Barrett ◽  
Robert DeConto ◽  
Robert Dunbar ◽  
Colm Ó Cofaigh ◽  
...  
Keyword(s):  
Case Studies ◽  
Numerical Models ◽  
Full Range ◽  
Ice Sheet ◽  
Geological Evidence ◽  
Last Glacial ◽  
Recent Advances ◽  
Climate Evolution

AbstractGeological evidence shows that the ice sheet and climate in Antarctica has changed considerably since the onset of glaciation around 34 million years ago. By analysing this evidence, important information concerning processes responsible for ice sheet growth and decay can be determined, which is vital for appreciating future changes in Antarctica. Geological records are diverse and their analyses require a variety of techniques. They are, however, essential for the establishment of hypotheses regarding past Antarctic changes. Numerical models of ice and climate are useful for testing such hypotheses, and in recent years there have been several advances in our knowledge relating to ice sheet history gained from these tests. This paper documents five case studies, employing a full range of techniques, to exemplify recent insights into Antarctic climate evolution from modelling ice sheet inception in the earliest Oligocene to quantifying Neogene ice sheet fluctuations and process-led investigations of recent (last glacial) changes.

Seismic Assessment and Retrofitting of an Under-Designed RC Frame Through a Displacement-Based Approach

2017 ◽  
pp. 36-58
Author(s):  
Marco Valente ◽  
Gabriele Milani
Keyword(s):  
Seismic Response ◽  
Numerical Models ◽  
Seismic Assessment ◽  
Original Structure ◽  
Rc Frame ◽  
Existing Structures ◽  
Dynamic Analyses ◽  
Non Linear ◽  
Displacement Based ◽  
Southern European Countries

Many existing reinforced concrete buildings were designed in Southern European countries before the introduction of modern seismic codes and thus they are potentially vulnerable to earthquakes. Consequently, simplified methodologies for the seismic assessment and retrofitting of existing structures are required. In this study, a displacement based procedure using non-linear static analyses is applied to a four-storey RC frame in order to obtain an initial estimation of the overall inadequacy of the original structure as well as the extent of different retrofitting interventions. Accurate numerical models are developed to reproduce the seismic response of the RC frame in the original configuration. The effectiveness of three different retrofitting solutions countering structural deficiencies of the RC frame is examined through the displacement based approach. Non-linear dynamic analyses are performed to assess and compare the seismic response of the frame in the original and retrofitted configurations.

Analytical and Low-Order Numerical Modeling of Ball-to-Ball Contact Friction in Linear Ball Bearings and Ball Screws

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Bo Lin ◽  
Molong Duan ◽  
Chinedum E. Okwudire
Keyword(s):  
Case Studies ◽  
Numerical Models ◽  
Experimental Studies ◽  
Point Contact ◽  
Ball Screw ◽  
Contact Friction ◽  
Ball Bearings ◽  
Friction Behavior ◽  
Ball Contact ◽  
Low Order

Analytical and low-order numerical models are very useful for studying friction behavior of rolling element machine components like ball bearings and ball screws. This is because they provide generalizable insights into friction behavior at much lower computational costs compared with high-order numerical models like finite element analysis (FEA). While analytical and low-order numerical models in the literature are mainly focused on ball-to-groove contact friction, experimental studies have shown that ball-to-ball contact friction is also very important. This is especially true for linear ball bearings/guideways and ball screws which, unlike rotary ball bearings, do not typically make use of caged balls to prevent ball-to-ball contact. Therefore, in this paper, low-order numerical models for ball-to-ball contact friction in linear ball bearings and ball screws are developed. Furthermore, an analytical model for ball-to-ball contact friction in four-point contact linear ball bearing is derived by making simplifications to its low-order numerical model. Compared with ball-to-ball friction predictions from FEA models developed in ansys, the proposed numerical models are shown in case studies to be accurate within 7%, while computing at least three orders of magnitude faster. Moreover, case studies are used to demonstrate how the developed models can be used in practice, e.g., for the mitigation of ball-to-ball contact friction in linear ball bearings and the prediction of friction variation during the operation of a ball screw.

scholarly journals Numerical models for slip on the subduction interface motivated by field observations

Lithosphere ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 322-332 ◽  
Author(s):  
Donald M. Fisher ◽  
John N. Hooker ◽  
David O.S. Oakley
Keyword(s):  
Numerical Models ◽  
Field Observations
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