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  • 1
    Publication Date: 2018-09-11
    Description: Functionally graded materials (FGMs) are materials in which the spatial chemical composition and microstructure gradually change resulting in a corresponding spatial change in the material properties. For this study, grade 5 titanium alloy (Ti6Al4V) and titanium carbide (TiC) powders were co-sintered using laser metal deposition (LMD) on Ti6Al4V substrate. The challenge of this process was determining the process parameters that minimizes or prevent macro cracking due to high thermal gradients and hence the residual stresses. The aim was to determine the optimum parameters. The laser energy density (LED) was used to characterize the processing parameters applied. It was found that when the energy density is in the range of 15 – 25 MJ/m 2 , the FGM cracked. When the energy density is in the range of 12 – 16 MJ/m 2 , the FGM did not crack.
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 2
    Publication Date: 2006-02-04
    Description: Until now, continental shelf environments have been monitored with highly localized line-transect methods from slow-moving research vessels. These methods significantly undersample fish populations in time and space, leaving an incomplete and ambiguous record of abundance and behavior. We show that fish populations in continental shelf environments can be instantaneously imaged over thousands of square kilometers and continuously monitored by a remote sensing technique in which the ocean acts as an acoustic waveguide. The technique has revealed the instantaneous horizontal structural characteristics and volatile short-term behavior of very large fish shoals, containing tens of millions of fish and stretching for many kilometers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Makris, Nicholas C -- Ratilal, Purnima -- Symonds, Deanelle T -- Jagannathan, Srinivasan -- Lee, Sunwoong -- Nero, Redwood W -- New York, N.Y. -- Science. 2006 Feb 3;311(5761):660-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Ocean Science and Engineering, Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. makris@mit.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16456080" target="_blank"〉PubMed〈/a〉
    Keywords: Acoustics ; Animals ; Atlantic Ocean ; Behavior, Animal ; Ecosystem ; *Fishes ; Oceanography ; Population Density ; Population Dynamics ; *Seawater ; Time
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2009-03-28
    Description: Similarities in the behavior of diverse animal species that form large groups have motivated attempts to establish general principles governing animal group behavior. It has been difficult, however, to make quantitative measurements of the temporal and spatial behavior of extensive animal groups in the wild, such as bird flocks, fish shoals, and locust swarms. By quantifying the formation processes of vast oceanic fish shoals during spawning, we show that (i) a rapid transition from disordered to highly synchronized behavior occurs as population density reaches a critical value; (ii) organized group migration occurs after this transition; and (iii) small sets of leaders significantly influence the actions of much larger groups. Each of these findings confirms general theoretical predictions believed to apply in nature irrespective of animal species.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Makris, Nicholas C -- Ratilal, Purnima -- Jagannathan, Srinivasan -- Gong, Zheng -- Andrews, Mark -- Bertsatos, Ioannis -- Godo, Olav Rune -- Nero, Redwood W -- Jech, J Michael -- New York, N.Y. -- Science. 2009 Mar 27;323(5922):1734-7. doi: 10.1126/science.1169441.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. makris@mit.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19325116" target="_blank"〉PubMed〈/a〉
    Keywords: Animal Migration ; Animals ; Atlantic Ocean ; *Behavior, Animal ; Ecosystem ; Fishes/*physiology ; Population Density ; Reproduction ; Spatial Behavior ; *Swimming ; Time Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2016-03-05
    Description: Observing marine mammal (MM) populations continuously in time and space over the immense ocean areas they inhabit is challenging but essential for gathering an unambiguous record of their distribution, as well as understanding their behaviour and interaction with prey species. Here we use passive ocean acoustic waveguide remote sensing (POAWRS) in an important North Atlantic feeding ground to instantaneously detect, localize and classify MM vocalizations from diverse species over an approximately 100,000 km(2) region. More than eight species of vocal MMs are found to spatially converge on fish spawning areas containing massive densely populated herring shoals at night-time and diffuse herring distributions during daytime. We find the vocal MMs divide the enormous fish prey field into species-specific foraging areas with varying degrees of spatial overlap, maintained for at least two weeks of the herring spawning period. The recorded vocalization rates are diel (24 h)-dependent for all MM species, with some significantly more vocal at night and others more vocal during the day. The four key baleen whale species of the region: fin, humpback, blue and minke have vocalization rate trends that are highly correlated to trends in fish shoaling density and to each other over the diel cycle. These results reveal the temporospatial dynamics of combined multi-species MM foraging activities in the vicinity of an extensive fish prey field that forms a massive ecological hotspot, and would be unattainable with conventional methodologies. Understanding MM behaviour and distributions is essential for management of marine ecosystems and for accessing anthropogenic impacts on these protected marine species.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wang, Delin -- Garcia, Heriberto -- Huang, Wei -- Tran, Duong D -- Jain, Ankita D -- Yi, Dong Hoon -- Gong, Zheng -- Jech, J Michael -- Godo, Olav Rune -- Makris, Nicholas C -- Ratilal, Purnima -- England -- Nature. 2016 Mar 17;531(7594):366-70. doi: 10.1038/nature16960. Epub 2016 Mar 2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory for Ocean Acoustics and Ecosystem Sensing, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, USA. ; Laboratory for Undersea Remote Sensing, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA. ; Northeast Fisheries Science Center, 166 Water Street, Woods Hole, Massachusetts 02543, USA. ; Institute of Marine Research, Post Office Box 1870, Nordnes, N-5817 Bergen, Norway.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26934221" target="_blank"〉PubMed〈/a〉
    Keywords: Acoustics ; Animals ; Aquatic Organisms/*physiology ; Atlantic Ocean ; Diet/veterinary ; Ecosystem ; *Feeding Behavior ; Fishes/*physiology ; Male ; Mammals/*physiology ; *Predatory Behavior ; Time Factors ; *Vocalization, Animal ; Whales/physiology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2018-09-10
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Institute of Physics
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  • 6
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