Wave tank studies were conducted to determine the kinematics of “small” ice masses in storm waves typical of the Grand Banks region (10–14-s periods, 12–15-m heights). The models tested spanned the range of full-scale masses from growlers and bergy bits (10–103 tonnes), to small icebergs (104–105 tonnes). In open water, models smaller than 1/13 wavelength behaved essentially as particles of fluid. The corresponding full-scale kinetic energies associated with such motions could exceed 107 J. Models approximately 1/2 wavelength in size could attain energies in the surge direction in excess of 109 J, largely through wave diffraction effects. Significant heave resonance motions were also seen. Tank studies additionally revealed that wave-driven ice-structure impacts of substantial energy could occur, although wave diffraction from the structure could also have a considerable influence on nearby ice motion. The conclusion is reached that wave-induced motion of small ice masses represents a significant environmental hazard to the operation of offshore structures in ice-infested waters.

About half of Earth's land mass experiences mean temperatures below 0°C during the coldest month. Attendant conditions pose major challenges to the operation of off-road autonomous vehicles. Low-temperature effects on lubricants, materials, and batteries can impair a robot's ability to operate at all. Cold starting will be a serious problem if missions require long periods of engine shutdown. Deep snow can easily immobilize vehicles on terrain that would otherwise pose no problems. Blowing snow and icing can also degrade the performance of sensors needed for navigation and target detection. Winter operation of passenger vehicles and construction equipment provides guidance to surmount cold-regions effects on robotic vehicles. This report identifies problems likely to be encountered, simple preventative measures, and references for additional information. Conditions are sufficiently demanding that off-road autonomous vehicles must be designed for and tested in cold regions if they are expected to operate there successfully. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN IT IS NO LONGER NEEDED. DO NOT RETURN TO THE ORIGINATOR.

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Les jeunes mammiferes acquierent en general leur independance grace aux modifications de comportement de leurs meres qui, en particulier, les repoussent peu a peu.Selon certains travaux, le rejet du jeune phoque par sa mere ne serait pas du au sevrage proprement dit mais plutöt au fait que, pendant la poriode d'allaitement, la mere s'assure que son jeune est pres d'elle puisque c'est toujours eile qui rinitie a teter.Nos recherches sur les phoques veaux marins de Miquelon contredisent ces affirmations et confirment au contraire que, chez ces animaux, 1'interaction mere-jeune est du type habituel chez les mammiferes.

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