Nanometers-thick self-organized Fe stripes: bridging the gap between surfaces and magnetic materials

We have fabricated 5nm-high Fe(110) stripes by self-organized (SO) growth on a slightly vicinal R(110)/Al2O3(11-20) surface, with R=Mo, W. Remanence, coercivity and domain patterns were observed at room temperature (RT). This contrasts with conventional SO epitaxial systems, that are superparamagnetic or even non-magnetic at RT due to their flatness. Our process should help to overcome superparamagnetism without compromise on the lateral size if SO systems are ever to be used in applications

Evolution of space programs governance

This chapter discusses the evolution of space programs governance from the “Old Space” paradigm to the “New Space” one. For both paradigms, we discuss archetypical governance models, rationale, pros and cons. Ultimately, we explain the driving forces underpinning the evolution of program governance models. We show three governance archetypes. Traditionally program architectures and governance models were quite homogeneous and mostly government-led (archetype 1), while in the “New Space” paradigm, programs may also include partnerships with private actors (archetype 2) or being directly led and owned by private actors (archetype 3)

What is value in the New Space Economy? The end-users’ perspective on satellite data and solutions

New industrial dynamics are disrupting the space sector. New stakeholders bringing in capital, technologies, and knowledge from other industries are developing next-generation space infrastructures and services. Both commercial and institutional space projects have to be valuable for a wider set of end-users, asking not only for economic returns but also social and environmental benefits. Space organizations urge understanding and fostering value in the New Space Economy ecosystem. Indeed, end-users are still struggling to enact the expected value of satellite data and solutions for their business. This paper aims to investigate the expected value and the level of adoption (enacted value) of satellite data and satellite-based solutions in the New Space Economy ecosystem from end-users’ perspective. We interviewed 21 managers from end-user organizations in different sectors (i.e., Insurance & Finance, Energy & Utility, Transportation & Logistics). Value is deeply discussed in general management literature, and we identify Value Theory as the theoretical lens with the most explanatory power for the phenomenon under examination. From the end-users’ perspective, we frame the expected value and the enacted value in taking strategic and tactical decisions regarding their activities, services and products, laying the foundations for further studies of value mechanisms in the New Space ecosystem. Our research set a theoretical and conceptual foundation on value in the New Space ecosystem. It also delineates the blurred boundaries of the New Space ecosystem, the main stakeholders involved, and their perception of value. Insights and implications for strategic and innovation management are also provided. Practitioners may exploit our research results and leverage the end-users-oriented framework to develop next-generation space projects in the New Space ecosystem. We also discuss the limitations and further developments of this research

Path-tracking of a tractor-trailer vehicle along rectilinear and circular paths: A Lyapunov-based approach

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Temperature dependence of surface stress across an order-disorder transition: p(1x2)O/W(110)

Strain relaxations of a p(1x2) ordered oxygen layer on W(110) are measured as a function of temperature across the disordering transition using low-energy electron diffraction. The measured strains approach values of 0.027 in the [1-10] and -0.053 in the [001] direction. On the basis of the measured strain relaxations, we give quantitative information on temperature-dependent surface stress using the results of ab initio calculations. From the surface formation energy for different strains, determined by first-principles calculations, we estimate that surface stress changes from -1.1 for the ordered phase to -0.2N/m for the disordered one along [1-10], and from 5.1 to 3.4 N/m along [001]. Moreover, our observation that the strains scale inversely with domain size confirms that the strain relaxation takes place at the domain boundaries.Comment: 8 pages, 5 figure

Physical properties of the jet from DG Tauri on sub-arcsecond scales with HST/STIS

We derive the physical properties at the base of the jet from DG Tau both along and across the flow and as a function of velocity. We analysed seven optical spectra of the DG Tau jet, taken with the Hubble Space Telescope Imaging Spectrograph. The spectra were obtained by placing a long-slit parallel to the jet axis and stepping it across the jet width. The resulting position-velocity diagrams in optical forbidden emission lines allowed access to plasma conditions via calculation of emission line ratios. We find at the base of the jet high electron density, $n_e \sim$ 10$^5$, and very low ionisation, $x_e \sim 0.02-0.05$, which combine to give a total density up to $n_H \sim$ 3 10$^6$. This analysis confirms previous reports of variations in plasma parameters along the jet, (i.e. decrease in density by several orders of magnitude, increase of $x_e$ from 0.05 to a plateau at 0.7 downstream at 2$''$ from the star). Furthermore, a spatial coincidence is revealed between sharp gradients in the total density and supersonic velocity jumps. This strongly suggests that the emission is caused by shock excitation. The position-velocity diagrams indicate the presence of both fast accelerating gas and slower, less collimated material. We derive the mass outflow rate, $\dot{M}_j$, in the blue-shifted lobe in different velocity channels, that contribute to a total of $\dot{M}_j \sim$ 8 $\pm$ 4 10$^{-9}$ M$_\odot$ yr$^{-1}$. We estimate that a symmetric bipolar jet would transport at the low and intermediate velocities probed by rotation measurements, an angular momentum flux of $\dot{L}_j \sim$ 2.9 $\pm$ 1.5 10$^{-6}$ M$_\odot$ yr$^{-1}$ AU km s$^{-1}$. The derived properties of the DG Tau jet are demonstrated to be consistent with magneto-centrifugal theory. However, non-stationary modelling is required in order to explain all of the features revealed at high resolution.Comment: 16 pages, 18 figure

Egg hatching at different temperatures and relative humidities in Idaea inquinata (Scopoli) (Lepidoptera: Geometridae)

Idaea inquinata (Scopoli) feeds mainly on dried plants, nevertheless, it is also a potential pest of stored products as it is able to develop on cereal products. The few references on the biology of this species do not deal with the influence of temperature and relative humidity on egg hatching. To fill this gap, groups of 100 eggs, 24-48 hours old, were exposed to five constant temperatures (17, 21, 26, 29 and 34±1°C), two relative humidities (35 and 70±5%) and a photoperiod of 0:24 (light:dark); ten tests were carried out. Each test was replicated four times and egg hatching was observed daily. The highest mean number of hatched eggs was observed at 26 and 29±1°C, 70±5% r.h. with 91.5 and 91.0 eggs, respectively. The lowest mean number of hatched eggs was 61.5 observed at 17°C and 70±5% r.h. The mean numbers of hatched eggs, 83.5, 77.5, 78.5 and 79.8 were similar at 21, 26, 29 and 34±1°C, 35±5% r.h., respectively. Eggs hatched between the sixth and the eighth day at all the temperatures tested, except for 17±1°C and 35±5% r.h., where hatching started on the twelfth day. At this temperature, the duration of the hatching period increased with increasing humidity: 11 d at 35% r.h. and 15 d at 70% r.h. Keywords: Egg, Hatching, Temperature, Relative humidity, Rusty wave mot

Analysis of some global optimization algorithms for space trajectory design

In this paper, we analyze the performance of some global search algorithms on a number of space trajectory design problems. A rigorous testing procedure is introduced to measure the ability of an algorithm to identify the set of ²-optimal solutions. From the analysis of the test results, a novel algorithm is derived. The development of the novel algorithm starts from the redefinition of some evolutionary heuristics in the form of a discrete dynamical system. The convergence properties of this discrete dynamical system are used to derive a hybrid evolutionary algorithm that displays very good performance on the particular class of problems presented in this paper