On a problem of thermo-viscoelasticity

Analysis of viscoelastic materials under transient thermal conditions related to solid rocket propellant

Further measurements and observations on the Cromwell Current

The Cromwell Current was observed in the eastern Pacific during the Scripps Institution of Oceanography SWAN SONG Expedition, 5 September–1 December 1961, employing hydrographic stations and direct current measurements. The velocity structure in 1961 at 140°W was similar to that observed in April 1958 except that the transport in 1961 was only 22 × 106 m3 /sec---55% of the transport observed in 1958...

Mapping the Impacts of Climate Change on Mediterranean Viticulture

Climate change will have a profound impact on viticulture across the planet in the coming decades. Viticulture in the Mediterranean Basin will be disproportionately affected, as it is considered a climate change hotspot. This study focuses on how the vineyards of three notable wine regions in southern France will be affected by projected changes in average annual temperature, total annual precipitation, average length of droughts, and average volumetric soil water (VSW) content in layer 1 soils due to climate change. Vineyard soils will also be affected by climate change in this region, indirectly impacting grape cultivation as well. A GIS approach was taken to display the difference in these climate variables on southern French vineyards between 2020 and 2050. Raster and vector datafiles from the Copernicus Land Monitoring Service and the Copernicus Climate Change Service were used under two French climate projection models and the RCP 4.5 climate scenario. The results of this GIS comparison indicated an increase in average annual temperature and average length of dry spells, a decrease in total annual precipitation, and relatively similar average VSW content on southern French vineyards by 2050. Grapes in this region will likely experience a decrease in desired flavors and other specific qualities for wine-production largely due to a shift in grapevine phenology driven by warmer temperatures throughout the growing season. Vineyards are also likely to yield a smaller quantity of usable wine grapes at harvest due to water stress. The stability, and even increase, in VSW content despite less precipitation and longer droughts indicates that there may be other facets of climate change that will impact soil moisture and, thus, viticulture in the future. There are strategies that can be used to mitigate the effects of climate change on viticulture and winemaking, including agricultural approaches and the blending of introduced resistant grape varieties with traditionally grown varieties to maintain quality and quantity

Observations of internal waves of tidal period made with neutrally buoyant floats

Neutrally buoyant current floats at depths between 500 and 2500 m at 28°12\u27N, 139°07\u27W and 28° 48\u27N, 117° 41\u27W exhibited a marked periodic motion. The floats moved in clockwise orbits at speeds of 5- 18 cm/sec and with a period of approximately 25 hours. The orbital is approximately equal to the inertial period. Floats tracked simultaneously at different depths were not in phase. With one exception, such motion has not been observed at other latitudes. It is believed that the observed motion was a result of internal waves and that such motions are restricted to a rather narrow belt of latitude

A Mechanical Model for Elastic Fiber Microbuckling

A two-dimensional mechanical model is presented to predict the compressive strength of unidirectional fiber composites using technical beam theory and classical elasticity. First, a single fiber resting on a matrix half-plane is considered. Next, a more elaborate analysis of a uniformly laminated, unidirectional fiber composite half-plane is presented. The model configuration incorporates a free edge which introduces a buckling mode that originates at the free edge and decays into the interior of the half-plane. It is demonstrated that for composites of low volume fraction (<0.3), this decay mode furnishes values of buckling strain that are below the values predicted by the Rosen (1965) model. At a higher volume fraction the buckling mode corresponds to a half wavelength that is in violation of the usual assumptions of beam theory. Causes for deviations of the model prediction from existing experimental results are discussed

A technique for measuring deep ocean currents close to the bottom with an unattached current meter, and some preliminary results

A new system for measuring deep ocean currents close to the bottom is described. The device is moored in suspension with a float. Four sets of measurements, totaling 75.8 hours, were made at depths down to 5337 m. For one 16-hour period, a steady current of 17 cm/sec was recorded 3.5 m from the bottom at 5192 m. One measurement at 3584 m, 60 miles northeast of Cape Hatteras, indicates that the Gulf Stream extended to the bottom in this region

ACon: A learning-based approach to deal with uncertainty in contextual requirements at runtime

Context: Runtime uncertainty such as unpredictable operational environment and failure of sensors that gather environmental data is a well-known challenge for adaptive systems. Objective: To execute requirements that depend on context correctly, the system needs up-to-date knowledge about the context relevant to such requirements. Techniques to cope with uncertainty in contextual requirements are currently underrepresented. In this paper we present ACon (Adaptation of Contextual requirements), a data-mining approach to deal with runtime uncertainty affecting contextual requirements. Method: ACon uses feedback loops to maintain up-to-date knowledge about contextual requirements based on current context information in which contextual requirements are valid at runtime. Upon detecting that contextual requirements are affected by runtime uncertainty, ACon analyses and mines contextual data, to (re-)operationalize context and therefore update the information about contextual requirements. Results: We evaluate ACon in an empirical study of an activity scheduling system used by a crew of 4 rowers in a wild and unpredictable environment using a complex monitoring infrastructure. Our study focused on evaluating the data mining part of ACon and analysed the sensor data collected onboard from 46 sensors and 90,748 measurements per sensor. Conclusion: ACon is an important step in dealing with uncertainty affecting contextual requirements at runtime while considering end-user interaction. ACon supports systems in analysing the environment to adapt contextual requirements and complements existing requirements monitoring approaches by keeping the requirements monitoring specification up-to-date. Consequently, it avoids manual analysis that is usually costly in today’s complex system environments.Peer ReviewedPostprint (author's final draft

Internal Stresses in Laminated Construction

This report reviews the procedure employed in an investigation of the sources and influence of internal stresses in laminated construction, and discusses the influence of shrinkage and swelling stresses caused by atmospheric conditions upon the tensile strength across grain in laminated construction with special reference to airplane propellers. The investigation covered three sources of internal stress, namely, the combination of plain-sawed and quarter-sawed material in the same construction, the gluing together of laminations of different moisture contents, and the gluing together of laminations of different densities. Glued specimens and free specimens, made up under various manufacturing conditions, were subjected to various climatic changes inducing internal stresses and then were tested

Scattering from supramacromolecular structures

We study theoretically the scattering imprint of a number of branched supramacromolecular architectures, namely, polydisperse stars and dendrimeric, hyperbranched structures. We show that polydispersity and nature of branching highly influence the intermediate wavevector region of the scattering structure factor, thus providing insight into the morphology of different aggregates formed in polymer solutions.Comment: 20 pages, 8 figures To appear in PR