Experimental Evaluation of On-Board Contact-Graph Routing Solutions for Future Nano-Satellite Constellations

Hardware processing performance and storage capability for nanosatellites have increased notably in recent years. Unfortunately, this progress is not observed at the same pace in transmission data rate, mostly limited by available power in reduced and constrained platforms. Thus, space-to-ground data transfer becomes the operations bottleneck of most modern space applications. As channel rates are approaching the Shannon limit, alternative solutions to manage the data transmission are on the spot. Among these, networked nano-satellite constellations can cooperatively offload data to neighboring nodes via frequent inter-satellite links (ISL) opportunities in order to augment the overall volume and reduce the end-to-end data delivery delay. Nevertheless, the computation of efficient multi-hop routes needs to consider not only present satellite and ground segments as nodes, but a non-trivial time dynamic evolution of the system dictated by orbital dynamics. Moreover, the process should properly model and rely on considerable amount of available information from node’s configuration and network status obtained from recent telemetry. Also, in most practical cases, the forwarding decision shall happen in orbit, where satellites can timely react to local or in-transit traffic demands. In this context, it is appealing to investigate on the applicability of adequate algorithmic routing approaches running on state-of-the-art nanosatellite on-board computers. In this work, we present the first implementation of Contact Graph Routing (CGR) algorithm developed by the Jet Propulsion Laboratory (JPL, NASA) for a nanosatellite on-board computer. We describe CGR, including a Dijkstra adaptation operating at its core as well as protocol aspects depicted in CCSDS Schedule-Aware Bundle Routing (SABR) recommended standard. Based on JPL’s Interplanetary Overlay Network (ION) software stack, we build a strong baseline to develop the first CGR implementation for a nano-satellites. We make our code available to the public and adapt it to the GomSpace toolchain in order to compile it for the NanoMind A712C on-board flight hardware based on a 32-bit ARM7 RISC CPU processor. Next, we evaluate its performance in terms of CPU execution time (Tick counts) and memory resources for increasingly complex satellite networks. Obtained metrics serve as compelling evidence of the polynomial scalability of the approach, matching the predicted theoretical behavior. Furthermore, we are able to determine that the evaluated hardware and implementation can cope with satellite networks of more than 120 nodes and 1200 contact opportunities

Predicting PSR Filters by Transverse Relaxation Enhancements

The paramagnetic spin relaxation (PSR) filter allows the suppression of the NMR resonances of individual components in mixtures according to their Gd3+-complexing ability. The difficulty in predicting this property hampers, however, the widespread application of this filter. Herein we describe that the PSR filter is dominated by the transverse relaxation enhancement (R2p) experienced by nuclei in the presence of Gd3+, so that R2p represents a reliable predictive tool of suppression in the 1D and 2D PSR filter of complex mixtures. The robustness of R2p as a predictive tool in PSR filters has been demonstrated at different magnetic fields and for the 1H, 13C, COSY, and HMQC filtering of commercial multicomponent compositions, including beverages and drugsThis work was financially supported by the Spanish Government (CTQ2012-34790, CTQ2012-33436) and the Xunta de Galicia (CN2011/037). L.F.P. thanks the Portuguese Foundation for Science and Technology (FCT MCTES) for a Ph.D. grant (SFRH/BD/37341/2007)S

The Learning of Mind Mapping in Higher Education: A Comparative Study Between Universidad de Córdoba and Università di Roma-La Sapienza

In this paper we propose Mind Mapping as a technique which enhances holistic learning or whole brain learning in higher education. The dynamics performed in the learning and application of Mind Mapping is part of a participatory approach in the classroom as an element of the learning process. The research approach follows a quantitative methodology. The results reflect the views of students about the learning of Mind Mapping and its effectiveness in the study. The findings indicate that mental maps can be used with any type of material, making it a tool applicable to any university degree course

Mapping the Mechanical Properties of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Banded Spherulites by Nanoindentation

Nanoindentation provides clear evidence that spherulite banding can be associated with a continuous modulation of mechanical properties from the more compliant peaks to the stiffer valleys. The structural arrangement in polymer-banded spherulites has intrigued scientists for many decades, and the debate has been recently intensified with the advent of new experimental evidence. The present paper approaches this issue by exploring the local mechanical properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-ringed spherulites via nanoindentation and discussing the confidence of the results. It was found that storage modulus and hardness across the banding morphology can be described as a sequence of regular oscillations with a periodicity that exactly matches the one observed using optical and atomic force microscopy. Results are consistent with the model of regular twisting of the lamellae, with flat-on arrangement in the low regions and edge-on lamellae in the crests.The authors wish to thank the MINECO (Ministerio de Economía y Competitividad), Spain, for funding the research reported under grants MAT2013-47898-C2-1-R (covering the costs to publish in open access) and MAT2012-36341. Patricia Enrique-Jimenez acknowledges MINECO for a FPI (Formación Personal Investigador) studentship. We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)

Parto y distocias en la perra y en la gata

El conocimiento de la fisiología normal del parto, eutocia, resulta indispensable para reconocer y, por lo tanto, establecer un adecuado plan de actuación clínica ante un parto patológico o distócico. En la primera parte de este artículo revisamos los mecanismos del parto en la perra y en la gata poniendo especial interés en aquellos aspectos de mayor trascendencia clínica; posteriormente estudiamos el parto patológico, su diagnóstico y las técnicas obstétricas que debemos emplear para resolver el problema que plantea un parto distócico en los animales de compañía.An adequate knowledge of the physiological parturition, eutocya, results essential in order to recognize and then establishing an accurate plan of clinicalperformance, to cope with the pathological whelping or dystocia. That's why in the first part of this article the mechanism of parturition in the bitch and the queen are reviewed, watching especiaUythose aspects of clinical significance; after this we study the pathological parturition, its identification and the obstetrical techniques to use in order to get successin the resolution of the trouble that a dystocia in companion animals represents

Determination of field capacity and yield mapping in olive harvesting using remote data acquisition

Sensors, communication systems and geo-reference units are required to achieve an optimized management of agricultural inputs with respect to the economic and environmental aspects of olive groves. In this study, three commercial olive harvesters were tracked in Spain and Chile using remote and autonomous equipment to determine their time efficiency and field capacity. An experimental methodology for analyzing the data to determine the field capacity and efficiency is proposed, which, along with a conventional methodology, was used to analyze the data to determine field capacity and efficiency. The results of both methodologies are compared to validate the suitability of the experimental methodology. Furthermore, a yield monitor was developed and evaluate using one of the tested olive harvesters. The results show that yield monitoring of olives is possible, but further research is needed to archieve a more reliable methodology

Insight into the melt processed Polylimonene oxide/Polylactic acid blends

In this work, the polymerization of limonene oxide (LO) has been optimized at room temperature with two different aluminium-based catalysts [AlMeX{2,6-(CHPh$_2$)$_2$-4-tBu-C$_6$H$_2$O}] (X = Me (1), Cl (2)). A fully bio-based ether, polylimonene oxide (PLO), has been synthesized with low molecular weight and good thermal stability, being a potential sustainable polymeric additive for other bio-based and biodegradable polymers such as polylactic acid (PLA). Hence, we have explored its ability to influence the thermal, mechanical and morphological properties of PLA by preparing their blends by melt processing. The addition of a low amount of PLO led to a nearly 10 $^\circ$C decrease in the PLA glass transition temperature. Moreover, a decrease in the PLA melting temperature and the degree of crystallinity was observed. Interestingly, a remarkable increase in the flexibility of PLA-based films was noticed. All the results point to the existence of strong interactions between the components, suggesting their partial miscibility.Comment: Polymer Chemistry (2023

Neutron detectors of 10B+ZnS(Ag) as an alternative to 3He-based installed in the Radiation Portal Monitors in homeland Security

Using Monte Carlo method features of 10B+ZnS(Ag) neutron detector under real operational conditions has been calculated, this results were compared against measurements. This detector is a viable substitute for 3He detectors installed in custom borders to prevent the illicit traffic of special nuclear materials, SNM

On the system performance of DFT-S-OFDM and CP-OFDM for 5G Uplink in mmWave band

Both conventional Cyclic Prefix Orthogonal Frequency Division Multiplexing (CP-OFDM) and Discrete Fourier Transform Spread OFDM (DFT-S-OFDM) have been adopted for their use in the Physical Uplink Shared Channel (PUSCH) in the 5G New Radio (NR) standard. While CP-OFDM can better exploit the frequency characteristics of the channel, DFTS-OFDM has the advantage of a lower peak-to-average power ratio (PAPR). Due to the interactions between PAPR and power amplifier (PA) non-linearity, users adopting DFT-S-OFDM waveform may benefit from a potentially higher PA efficiency and extend their coverage by increasing their transmit power. In this paper we study the uplink performance of both waveforms and their interaction with non-linear PA and uplink power control in the millimeter-wave (mmWave) band to determine their optimal operational range

Sub-250 fs, 650 kW Peak Power Harmonic Mode-Locked Fiber Laser with InN-based SESAM

43rd. European Conference on Optical Communication (ECOC 2017), Gothemburg, 17-21 Sept.We demonstrate ultrafast harmonically mode-locked fiber lasing in up to 6-km-long rings at 1.56μm with InN SESAM. Fundamental mode-locking with pulse width of 239fs, pulse energy of 155nJ and peak power of 650kW is achieved with a 1-km-long cavity.European CommissionMinisterio de Economía y CompetitividadComunidad de Madri