Neoproterozoic sedimentation on the northeast margin of Laurentia and the opening of Iapetus

1994 ◽  
Vol 131 (3) ◽  
pp. 291-299 ◽  
Author(s):  
N. J. Soper
Keyword(s):  
Shallow Water ◽  
Strain Hardening ◽  
East Greenland ◽  
Eastern Margin ◽  
Sedimentary Sequences ◽  
Pan African ◽  
Hardening Effect ◽  
The Pacific ◽  
The Future ◽  
Cordilleran Margin

AbstractVery thick shallow water sedimentary sequences were deposited in Neoproterozoic time along the future margins of Laurentia. On the eastern margin these include the Eleonore Bay and Hecla Hoek sequences of Greenland and Svalbard; these are described and their geotectonic context briefly reviewed. They present both geotectonic and geodynamic problems: why did subsidence continue for some 300 Ma prior to the opening of Iapetus, and how could 15–20 km of sediment be accommodated in an ensialic environment?Prolonged slow stretching appears to have affected the eastern margin of Laurentia while the western (Cordilleran) margin progressed through the rift-drift transition as the Pacific opened. It is proposed that expansion of the Pacific was associated with both the convergence of Proto-Gondwanan continental terranes during the Pan-African orogeny (the extended SWEAT hypothesis) and also the maintenance of very slow extension rates on the future Iapetus margin. The strain-hardening effect of slow stretching may have been inhibited by a continuous basin-fill of juvenile heat-producing Grenville detritus. The onset of subduction in the Pacific freed up this margin; major rifting took place between East Greenland and possibly the Tornquist margin of Baltica in Vendian time, followed by the opening of northern Iapetus.

Re-visioning obscure spaces

Thesis Eleven ◽  
2018 ◽  
Vol 145 (1) ◽  
pp. 77-98 ◽  
Author(s):  
Jose Jowel Canuday
Keyword(s):  
Social Spaces ◽  
Distinctive Features ◽  
Contemporary World ◽  
The Pacific ◽  
The Social ◽  
The World ◽  
The Future

In popular imagery, the littorals of Sulu and Zamboanga conjure visions of pirates, terrorists, and bandits marauding its rough seas, open shores, and rugged mountains. These bleak accounts render the region nothing but a violent and peripheral southern Philippine backdoor inconspicuous to the sophisticated constituencies of the world’s metropolitan centres. Obscured from these imageries are the lasting cosmopolitan traits of openness, flexibility, and reception of local folk to trans-local cultural streams that marked Sulu and Zamboanga as a globalised space across the ages and oceans. The distinctive features of these cosmopolitan sensibilities are strikingly discernible in inter-generationally shared narratives, artefacts, and performances that were continually renewed from the days when Sulu and Zamboanga served as a borderless trading and cultural enclave nestled at the crossroads of the Pacific and the Indian Oceans. These enduring cosmopolitan sensibilities are embodied in the blending, among others, of the time-honoured dance of pangalay and the pop-musical dance genre celebrated on actual, analogue, and digitally-mediated spaces of the contemporary world. Furthermore, these embodied sensibilities are evident in song compositions that proclaim the humanistic themes of hope, peace, and prosperity to their place and the world in ways that exemplify the local people’s broader sense of connections beyond the narrow association of family, community, ethnicity, religion, and identity. This mixed bag of age-old and recent imaginaries and cultural traffic evoke a sociality that link the social spaces of the troubled but once and current globalised region to continuing acts of transcendence in history, memory, and visions of the future. In these marginalized places, we can see an unyielding tradition of cultural re-adaptation and creativity made up of myriad everyday acts that are down-to-earth, pragmatic, interstitial, and practical cosmopolitanism.

Study on Dynamic Mechanical Response of TC21 Alloy

2011 ◽  
Vol 88-89 ◽  
pp. 674-678
Author(s):  
Shuang Zan Zhao ◽  
Xing Wang Cheng ◽  
Fu Chi Wang
Keyword(s):  
Flow Stress ◽  
High Strain Rate ◽  
Strain Rate ◽  
Strain Hardening ◽  
High Strain ◽  
Dynamic Flow ◽  
Dynamic Mechanical ◽  
Hardening Effect ◽  
High Strain Rate Deformation ◽  
Binary Morphology

Some results of an experimental study on high strain rate deformation of TC21 alloy are discussed in this paper. Cylindrical specimens of the TC21 alloys both in binary morphology and solution and aging morphology were subjected to high strain rate deformation by direct impact using a Split Hopkinson Pressure Bar. The deformation process is dominated by both thermal softening effect and strain hardening effect under high strain rate loading. Thus the flow stress doesn’t increase with strain rate at the strain hardening stage, while the increase is obvious under qusi-static compression. Under high strain rate, the dynamic flow stress is higher than that under quasi-static and dynamic flow stress increase with the increase of the strain rate, which indicates the strain rate hardening effect is great in TC21 alloy. The microstructure affects the dynamic mechanical properties of TC21 titanium alloy obviously. Under high strain rate, the solution and aging morphology has higher dynamic flow stress while the binary morphology has better plasticity and less prone to be instability under high strain rate condition. Shear bands were found both in the solution and aging morphology and the binary morphology.

Navigation clearance evaluation and marine simulations for the planning of new bridge spans

2021 ◽  
Author(s):  
Steve Kite ◽  
James Pitchforth ◽  
Sammy Yip ◽  
Paz Artejo ◽  
Gerardo Ramon Galang
Keyword(s):  
Theoretical Calculations ◽  
The Philippines ◽  
Marine Traffic ◽  
The Pacific ◽  
The Future ◽  
Marine Navigation ◽  
Bridge Spans ◽  
Future Growth

<p>The sizing of the main span dimensions for new marine bridge crossings needs to consider the current shipping vessels using the waterways and the future growth in marine traffic. Internationally accepted guidelines are used for initial sizing of the navigation clearances, but confirmation of the safe passage of vessels requires simulations to be undertaken. For two major marine bridges planned in the Philippines the marine navigation clearance assessments have been carried out, and the results verified via realistic simulations carried out at the facilities available in the Maritime Academy of Asia and the Pacific (MAAP). This paper outlines methodology of the theoretical calculations and the simulations performed, which confirmed the clearances and informed the design of the required navigation aids.</p>

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