FPGA-based operational concept and payload data processing for the Flying Laptop satellite

Flying Laptop is the first small satellite developed by the Institute of Space Systems at the Universität Stuttgart. It is a test bed for an on-board computer with a reconfigurable, redundant and self-controlling high computational ability based on the field pro- grammable gate arrays (FPGAs). This Technical Note presents the operational concept and the on-board payload data processing of the satellite. The designed operational concept of Flying Laptop enables the achievement of mission goals such as technical demonstration, scientific Earth observation, and the payload data processing methods. All these capabilities expand its scientific usage and enable new possibilities for real-time applications. Its hierarchical architecture of the operational modes of subsys- tems and modules are developed in a state-machine diagram and tested by means of MathWorks Simulink-/Stateflow Toolbox. Furthermore, the concept of the on-board payload data processing and its implementation and possible applications are described

Experimental investigation of MHD impact on argon plasma flows by variation of magnetic flux density

The interaction between a probe body and argon plasma flow is investigated to examine to what extent the probe head temperature and the bow shock distance can be influenced by applying a strong magnetic field. The experiments are performed using a strong permanent magnet installed inside a probe body with a spherical, coated probe head. Former investigations showed strong influence on the bow shock geometry but also on the inflow plasma jet. Several boundary conditions have been varied to evaluate their influence toward the experiment. For an uncoated probe head the measured MHD impact was found to be of the same order of magnitude as for the coated case. Electrical isolation of the probe toward the vacuum chamber yielded only slight influence. The variation of the field strength was realized by changing the amount of magnet segments installed. Pictures were analyzed to minute the MHD interaction for each test case. It was found that the bow shock distance increased and the temperature of the probe head decreased while increasing the magnetic field density. This analysis precedes a thorough characterization of the plasma condition

Sample return of interstellar matter (SARIM)

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Associations between depressive symptoms and disease progression in older patients with chronic kidney disease: results of the EQUAL study

Background Depressive symptoms are associated with adverse clinical outcomes in patients with end-stage kidney disease; however, few small studies have examined this association in patients with earlier phases of chronic kidney disease (CKD). We studied associations between baseline depressive symptoms and clinical outcomes in older patients with advanced CKD and examined whether these associations differed depending on sex. Methods CKD patients (>= 65 years; estimated glomerular filtration rate <= 20 mL/min/1.73 m(2)) were included from a European multicentre prospective cohort between 2012 and 2019. Depressive symptoms were measured by the five-item Mental Health Inventory (cut-off <= 70; 0-100 scale). Cox proportional hazard analysis was used to study associations between depressive symptoms and time to dialysis initiation, all-cause mortality and these outcomes combined. A joint model was used to study the association between depressive symptoms and kidney function over time. Analyses were adjusted for potential baseline confounders. Results Overall kidney function decline in 1326 patients was -0.12 mL/min/1.73 m(2)/month. A total of 515 patients showed depressive symptoms. No significant association was found between depressive symptoms and kidney function over time (P = 0.08). Unlike women, men with depressive symptoms had an increased mortality rate compared with those without symptoms [adjusted hazard ratio 1.41 (95% confidence interval 1.03-1.93)]. Depressive symptoms were not significantly associated with a higher hazard of dialysis initiation, or with the combined outcome (i.e. dialysis initiation and all-cause mortality). Conclusions There was no significant association between depressive symptoms at baseline and decline in kidney function over time in older patients with advanced CKD. Depressive symptoms at baseline were associated with a higher mortality rate in men

Alignment of the CMS tracker with LHC and cosmic ray data

© CERN 2014 for the benefit of the CMS collaboration, published under the terms of the Creative Commons Attribution 3.0 License by IOP Publishing Ltd and Sissa Medialab srl. Any further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation and DOI.The central component of the CMS detector is the largest silicon tracker ever built. The precise alignment of this complex device is a formidable challenge, and only achievable with a significant extension of the technologies routinely used for tracking detectors in the past. This article describes the full-scale alignment procedure as it is used during LHC operations. Among the specific features of the method are the simultaneous determination of up to 200 000 alignment parameters with tracks, the measurement of individual sensor curvature parameters, the control of systematic misalignment effects, and the implementation of the whole procedure in a multi-processor environment for high execution speed. Overall, the achieved statistical accuracy on the module alignment is found to be significantly better than 10μm

Laser Propulsion Standardization Issues

It is a relevant issue in the research on laser propulsion that experimental results are treated seriously and that meaningful scientific comparison is possible between groups using different equipment and measurement techniques. However, critical aspects of experimental measurements are sparsely addressed in the literature. In addition, few studies so far have the benefit of independent confirmation by other laser propulsion groups. In this paper, we recommend several approaches towards standardization of published laser propulsion experiments. Such standards are particularly important for the measurement of laser ablation pulse energy, laser spot area, imparted impulse or thrust, and mass removal during ablation. Related examples are presented from experiences of an actual scientific cooperation between NU and DLR. On the basis of a given standardization, researchers may better understand and contribute their findings more clearly in the future, and compare those findings confidently with those already published in the laser propulsion literature. Relevant ISO standards are analyzed, and revised formats are recommended for application to laser propulsion studies

Beam-Riding Simulation and Diagnostics for Beamed-Energy Vehicles

The separation of energy source and aerospace vehicle allows for a variety of sophisticated beamed-energy propulsion concepts. Beyond the question of the technological realization of suitable high power lasers, beam-riding of the vehicle plays a crucial role for the maturity of any remotely driven laser propulsion device. Whereas usually flight stability is experimentally analyzed with respect to lateral and angular motion separately, this paper presents an analytical approach to consider as well the independency of both movements. A quasi-continuous approximation of impulse coupling yields a system of coupled differential equations describing the laser-driven motion in a two-dimensional case. A specific matrix of flight dynamics is derived yielding necessary and sufficient criteria for beam-riding stability. This approach can be applied on experimental data of any beamed-energy vehicle and shows its inherent capabilities of beam-riding and possible needs of technological assistance measures, e.g. spin-stabilization. As an example, the specific matrix of flight dynamics of a parabolic laser-thermal thruster is derived from impulse field data of recent hovering experiments. The theoretical analysis of stability criteria and simulated flight trajectories is in good accordance with the experimentally found results which had shown poor flight stability due to the specific coupling between lateral and angular motion. Furthermore, it is shown that in the mentioned case an optimization of alignment accuracy at the launch position by one order of magnitude would lead to an increase of flight time by only 1 second. The theoretical criteria for beam-riding stability are analyzed for alternative options of lightcraft configurations with respect to mass, momentum of inertia and center-of-mass position. While theoretical configurations for 2D beam-riding stability are found, alternative concepts using spin-stabilization are discussed. Model limitations with respect to full 3D dimensionality and pulsed motion are briefly illustrated

Beam-Riding Analysis of a Parabolic Laser-thermal Thruster

Flight experiments with laser-propelled vehicles (lightcrafts) are often performed by wire-guidance or with spin-stabilization. Nevertheless, the specific geometry of the lightcraft’s optics and nozzle may provide for inherent beam-riding properties. These features are experimentally investigated in a hovering experiment at a small free fliight test range with an electron-beam sustained pulsed CO2 high energy laser. Laser bursts are adapted with a real-time control to lightcraft mass and impulse coupling for ascent and hovering in a quasi equilibrium of forces. The flight dynamics is analyzed with respect to the impulse coupling field vs. attitude, given by the lightcraft’s offset and its inclination angle against the beam propagation axis, which are derived from the 3Dreconstruction of the flight trajectory from highspeed recordings. The limitations of the experimental parameters’ reproducibility and its impact on flight stability are explored in terms of Julia sets. Solution statements for dynamic stabilization loops are presented and discussed

CO2 Laser Ablation Area Scaling and Redeposition on Flat Polyoxymethylene Targets

One of the remaining subjects of interest for laser ablation propulsion study is whether special benefits or challenges exist when applying a particularly large or small laser spot area to a target. This subject is of high importance for topics including laser removal of space debris, micropropulsion, and design of laser propulsion vehicles. Analysis of spot area-dependent effects is complex since ablation phenomena differ between atmosphere and vacuum conditions. Progress has also been impeded by the difficulty of setting control parameters (particularly fluence) constant while the spot area is adjusted. It is virtually impossible for one group to address small- and large-area effects using a single high-power laser system. Recent collaborative experiments using 100-J class and 10-J class CO2 lasers have advanced the understanding of laser propulsion area scaling. Experiments were conducted below the threshold for plasma formation. The dependence of various laser propulsion parameters on the laser spot area has been investigated within areas covering approximately 0.5-50 cm2 on the target

Update on CO2 Laser Ablation of Polyoxymethylene

Polyoxymethylene (POM) propellants have been studied since the 1970's, and perhaps represent the most promising match of a propellant to the CO2 laser for laser propulsion studies. Applications range from ground-launch of laser propulsion vehicles at atmospheric pressure to spacebased laser ablation propulsion microthrusters. In this paper we broadly update the state of understanding of CO2 laser ablation of POM based on new experiments conducted in Japan and Germany, with a focus on the basic physics of ablation of flat POM targets. Measurements using 10 J-class and 100 J-class lasers are compared to previous literature results for ablation of POM. Emphasis is placed on the influence of control parameters on ablation, especially the incident laser fluence and ambient pressure. New results highlight the influence of the ambient pressure on ablation physics from the vaporization threshold to the plasma regime, and clarify the role of the fluence in determining ablation behavior in air and vacuum environments. Imparted impulse and ablated mass were measured at the target using piezoelectric force sensors, impulse pendulums, and scientific balances. The new experimental investigations cover orders of magnitude in fluence (10E-2 to 10E3 J/cm2) and ambient pressure (10E-3 to 10E5 Pa)