24 research outputs found
A Pre-Landing Assessment of Regolith Properties at the InSight Landing Site
This article discusses relevant physical properties of the regolith at the Mars InSight landing site as understood prior to landing of the spacecraft. InSight will land in the northern lowland plains of Mars, close to the equator, where the regolith is estimated to be ≥3--5 m thick. These investigations of physical properties have relied on data collected from Mars orbital measurements, previously collected lander and rover data, results of studies of data and samples from Apollo lunar missions, laboratory measurements on regolith simulants, and theoretical studies. The investigations include changes in properties with depth and temperature. Mechanical properties investigated include density, grain-size distribution, cohesion, and angle of internal friction. Thermophysical properties include thermal inertia, surface emissivity and albedo, thermal conductivity and diffusivity, and specific heat. Regolith elastic properties not only include parameters that control seismic wave velocities in the immediate vicinity of the Insight lander but also coupling of the lander and other potential noise sources to the InSight broadband seismometer. The related properties include Poisson’s ratio, P- and S-wave velocities, Young’s modulus, and seismic attenuation. Finally, mass diffusivity was investigated to estimate gas movements in the regolith driven by atmospheric pressure changes. Physical properties presented here are all to some degree speculative. However, they form a basis for interpretation of the early data to be returned from the InSight mission.Additional co-authors: Nick Teanby and Sharon Keda
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Effects of proton bombardment on self-diffusion in silver: a preliminary report
Influence of the biobased economy on agricultural markets. Preperation of a modelling approach
This report is the conclusion of research undertaken to better understand the impact of the developing biobased economy on agricultural land markets. This has involved understanding the true dimension of the biobased economy, namely the large range of products for which a biobased component exists or could exist, and in this regard the likely evolution in the substitution of elements produced from fossil oil. This research is also a first step to determine whether the overall result of the development of the biobased economy will be positive, negative or neutral for the Dutch economy as a whole
Influence of the biobased economy on agricultural markets. Preperation of a modelling approach
This report is the conclusion of research undertaken to better understand the impact of the developing biobased economy on agricultural land markets. This has involved understanding the true dimension of the biobased economy, namely the large range of products for which a biobased component exists or could exist, and in this regard the likely evolution in the substitution of elements produced from fossil oil. This research is also a first step to determine whether the overall result of the development of the biobased economy will be positive, negative or neutral for the Dutch economy as a whole
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The possible occurrence of multi-phase behavior in the high T sub c superconductor YBa sub 2 Cu sub 3 O sub x
We report here the results obtained for powder diffraction studies on four YBa{sub 2}Cu{sub 3}O{sub x} samples in which a model with two orthorhombic phases was used to obtain an improved agreement. The implications of this structural model on the systematic variation of {Tc} with oxygen content will be discussed. 28 refs., 3 figs., 2 tabs