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Last decade's rapid growth of satellite constellation size has led to performance boosts and it has enabled unprecedented applications. However, this enlargement poses several challenges, especially related to their deployment and their economic viability. The problem is inherently multi-disciplinary and requires complex methods to explore its trade-space effectively. This work proposes a hybrid multi-objective method to concurrently select the optimal combination of launch opportunities and maneuvering strategies which minimizes time and cost. The method, using a combination of mixed-integer programming and heuristic optimization algorithms, allows for effective exploration of the coupling variables of the problem, thanks to the exploitation of the on-board propulsion and detailed launcher performance models. The results are applied to a set of case studies, comprising Starlink and a CubeSat constellation, demonstrating the capabilities of the methodology and its breadth of applicability in finding optimal deployment strategies including the launchers selection. • Optimal multi-objective constellation deployment, minimizing cost and duration. • Multi-disciplinary method including launcher selection and maneuvering strategies. • Mixed-integer programming combined with semi-analytical maneuvers for large systems. • Generalized maneuvering strategies exploiting Earth's natural perturbations. • Flexible launch manifest and launcher performance models for enhanced trade-offs. [ABSTRACT FROM AUTHOR]

This paper outlines the development phases of a wave-driven Helicon Plasma Thruster for cutting-edge Low Earth Orbit (LEO) constellations. The two-stage ambipolar electric propulsion (EP) system combines the efficient ionization of an ultra-compact helicon reactor with plasma acceleration based on an ambipolar electric field provided by a magnetic nozzle. This paper reveals maturation challenges associated with an emerging EP system in the hundreds-watt class, followed by outlook strategies. A 3 cm diameter helicon reactor was operated using argon gas under a time-modulated RF power envelope ranging from 250 W to 500 W with a fixed magnetic field strength of 400 G. Magnetically enhanced inductively coupled plasma reactor characteristics based on half-wavelength right helical and Nagoya Type III antennas under capacitive (E-mode), inductive (W-mode), and wave coupling (W-mode) were systematically investigated based on Optical Emission Spectroscopy. The operation characteristics of a wave-heated reactor based on helicon configuration were investigated as a function of different operating parameters. This work demonstrates the ability of two-stage HPT using a compact helicon reactor and a cusped magnetic field to outperform today's LEO spacecraft propulsion. [ABSTRACT FROM AUTHOR]

• Introduce a novel low-thrust constellation reconfiguration control method using artificial potential function. • Assure the Lyapunov stability including phase control and in the presence of perturbations. • Combine collision avoidance with reconfiguration simultaneously, lowering the risk of collision significantly. • Carry out comprehensive numerical simulations under diverse scenarios, including mega-constellation case. The configuration control of constellations which consist of numerous satellites presents significant challenges. Such space systems demand the capability for autonomous reconfiguration to accomplish specific missions. Individual satellites within constellations are primarily equipped with low-thrust systems, rendering traditional impulse control methods for satellite formation and mission planning ineffective. To address this issue, this paper proposes a low-thrust constellations reconfiguration control method utilizing an artificial potential function. Relying exclusively on neighboring state information, satellites can dynamically modulate their control efforts in real-time. The stability of the proposed reconfiguration control method is established under modelable, bounded perturbation using Lyapunov theory. Furthermore, a repulsive potential function is formulated to ensure collision avoidance among satellites. Numerical results indicate that the proposed method is stable, computationally efficient, and guarantees the safe distance during maneuvers. Consequently, this method is ideally suited for reconfiguration tasks across a spectrum of large space systems, including mega-constellations. [ABSTRACT FROM AUTHOR]

The Cislunar economy is thriving with innovative space systems and operation techniques to enhance and uplift the traditional approaches significantly. This paper brings about an approach for sustainable small satellite constellations to retain autonomy for long-term missions in the Cislunar space. The methodology presented is to align the hybrid model of the constellation for Earth and Moon as an integral portion of the Cislunar operations. These hybrid constellations can provide a breakthrough in optimally utilizing the Cislunar space to efficiently deploy prominent missions to be operated and avoid conjunction or collisions forming additional debris. Flower and walker constellation patterns have been combined to form a well-defined orientation for these small satellites to operate and deliver the tasks satisfying the mission objectives. The autonomous multi-parametric analysis for each constellation based in Earth and Moon's environment has been attained with due consideration to local environments. Specifically, the Solar Radiation Pressure (SRP) is a critical constraint in Cislunar operations and is observed during simulations. These are supported by conjunction analysis using the Monte Carlo technique and also the effect of the SRP on the operating small satellites in real-time scenarios. This is followed by the observed conclusions and the way forward in this fiercely competent Cislunar operation. [ABSTRACT FROM AUTHOR]

A COnstellation of Radiation BElt Survey (CORBES) program is proposed by the Sub-Group on Radiation Belt (SGRB) of TGCSS, COSPAR. To address the open qustions about the dynamics of the Earth’s radiation belt, CORBES mission would use a constellation of small/CubeSats to take an ultra-fast survey of the Earth’s radiation belt. The concept, science objectives and preliminary technical design of CORBES are introduced. This mission is an international multilateral cooperation mission coordinated by COSPAR. The SGRB Science Activities and COSPAR HQs Coordinate Activities on CORBES are summaried.

Current interest in spacecraft constellations for government and commercial uses continues to drive advancement in sophistication, capability, and mission complexity. As these systems proliferate, they require increased levels of automation to properly orchestrate in achieving the mission objectives. This paper develops a constellation planning capability for cross-link enabled Geospatial Intelligence missions. The planning for constellation coordination is performed using a two-level network flow approach, where the first level creates a communication plan, and the second layer determines the Earth sensing activities. A network flow method is used to simultaneously obtain a schedule for each unique satellite within the constellation and provides an optimal operational schedule for the entire cooperative system. [Display omitted] • Network flow optimizes the constellation with individual satellite operations. • Resulting satellite plans exist within the constrained feasible resource space. • Decoupling variables improves planning and data transport performance. [ABSTRACT FROM AUTHOR]

The amount of space debris is rising rapidly, and the number of satellites launched by humans is also growing. This poses a serious threat to the security of many important space assets including the International Space Station and the China Space Station. Due to the frequent occurrence of hazardous space conjunction (potential collisions) events, we aim to use a constellation composed of a few optical satellites to observe these space dangerous conjunction events, thereby improving the observation accuracy and timeliness of key conjunction events. We consider a variety of factors to establish an optical nanosatellite constellation design model, develop constellation observation efficiency evaluation criteria, construct a constellation configuration evaluation function, and design the performance parameters of space-based optical telescopes. The optimal orbit parameters and constellation configuration are obtained by using the genetic algorithm for optimization calculation. It is determined that a constellation of 6 satellites can track and observe more than 96% of potentially dangerous conjunction objects 24–48 h before a dangerous conjunction occurs. According to the observation data, high-precision orbit information of space objects can be obtained, which can reduce the collision false alarm rate by 99%. As a result, operators are notified to take collision avoidance measures only when the space object is truly in danger. This approach greatly reduces the number of avoidance operations caused by false early warnings, lowers the operating cost of space assets, and ensures the safety of space assets. [ABSTRACT FROM AUTHOR]

In order to assist the ever growing number of missions planned to visit the Moon, an international effort is being made to design and commission a communication and navigation lunar constellation of satellites. To this purpose, the goal of this study is to provide first a strategy to help the design of a small-sized lunar constellation, entailing different objectives and users to assist. Then, various optimised constellations are tested including the orbital users' filtering architectures, extracting insights on the state estimation achievable and its capability to support critical GNC tasks. Given the early stage design phase in which this study is carried out, the constellation design does not entail strong and clearly defined requirements yet. For such reason, a multi-objective optimisation (MOO) has been employed, which proved to be extremely beneficial, ensuring a correct amount of versatility to provide a large set of Pareto-optimal solutions. Different objectives associated to both various services and users have been put in place, exploring a search space based on classical Keplerian elements of the constellation servicers. To compare the resulting constellations and validate correctly the performance from a navigation perspective the users navigation scheme has been considered to be based on a GNSS/INS tightly coupled formulation. The GNSS receiver measurements are fused with accelerometer outputs through a navigation filter, providing thus a strategy where the absence of GNSS observables is partially covered by an inertial propagation of the on-board state. Attention is here focused on polar orbiters operational in Low Lunar Orbit (LLO) environment and the obtained results showed navigation capabilities good enough to enable correct execution of missions in the low lunar orbital region. [ABSTRACT FROM AUTHOR]

IPCBs (Intelligent Pseudolite Constellations based on high-altitude balloons) are a novel type of air-based pseudolite application with many advantages. Compared with ground-based pseudolites and traditional air-based pseudolites, IPCBs have a wider coverage and a lower energy requirement. Compared with LEO satellite constellations, IPCBs have a stronger signal, a lower cost, and a shorter deployment period. These merits give promising potential to IPCBs. In IPCB applications, one of the key factors is geometry configuration, which is deeply influenced by the balloon's unique features. The basic idea of this paper is to pursue a strategy to improve IPCB geometry performance by using diverse winds at different altitudes and balloons' capability of altering flight altitude intelligently. Starting with a brief introduction to IPCBs, this paper defines an indicator to assess IPCB geometry performance, an approach to adjust IPCB geometry configuration and an IPCB geometry configuration planning algorithm. Next, a series of simulations are implemented with an IPCB composed of six pseudolites in winds with/without a quasi-zero wind layer. Some IPCB geometry configurations are analyzed, and their geometry performances are compared. Simulation results show the effectiveness of the proposed algorithm and the influence of the quasi-zero wind layer on IPCB performance. [ABSTRACT FROM AUTHOR]

A quaternion, each component is in integers, is called a Lipschitz integer. A Lipschitz integer is called a primitive Lipschitz integer just if the greatest common divisor of its components is one. Complex-valued codes over Lipschitz integers are obtained accompanied by a respective modulo function. In this study, we demonstrate that some primitive Lipschitz integers, considered suitable for encoding, are inappropriate for constructing complex-valued codes over Lipschitz integers. To solve this problem, we investigate the primitive Lipschitz integers that have the "division with small remainder" property. We construct a named set "Encoder Lipschitz integers," consists of primitive Lipschitz integers that have the "division with small remainder" property. In addition, we examine some algebraic properties of this set. [ABSTRACT FROM AUTHOR]

The contribution deals with the typewritten concrete poetry of the intermedia artist Milan Adamčiak (1946 – 2017), which was created in the second half of the 1960s. It focuses on two characteristic forms of concrete poetry: verbal and sentence constellations. It observes how the principle of seriality is applied to these text-image compositions. Seriality, as a key compositional and meaning-generating principle, is particularly associated with repetition and variation. In the context of verbal constellations, the article emphasizes the function of visual composition in dealing with a word extracted from linguistic syntax. In sentence constellations, it concentrates on the metacritical function of these forms, specified in the form of a critique of language as a means of communication and an instrument of power. Adamčiak’s repetitive-variation manipulation of linguistic material represents the application of visual techniques to literary creation. The contribution also points out the intermedia character of Adamčiak’s concrete poetry, highlights its parallels and connections with Czech experimental poetry, and selectively considers the socio-political circumstances of the time.

Resumen Una ciudad es un proceso en formación constante, que acumula memoria superponiendo capas de información, contenida en hitos o “personas, cosas o hechos clave” que determinan el devenir de dicho proceso. Un plan urbanístico se presenta como un conjunto de nociones de dimensión morfológica y relacional detallados que generan una inercia hacia un objetivo concreto, lo que define un escenario utópico perseguido. La concreción de dicha escena convierte al plan en un elemento con baja probabilidad de ser materializado manteniendo la exactitud de lo previsto. Por ello, la altertopía nace necesariamente a la vez que la utopía: la altertopía es el universo infinito restante de alternativas al plan. Esta relación entre hitos y la implicación que tienen en la formación constante del proceso de ciudad se representa en la constelación La Paz–Bidebieta, caso de estudio paradigmático debido a su génesis de tabula rasa en un contexto autárquico, como barrio periférico de Donostia–San Sebastián promovido por la OSH en los años 60, avalando la fidelidad al Plan Parcial que lo originó. Abstract A city is a process in constant formation, which accumulates memory by overlapping layers of information, contained in milestones or "key people, things or events" that determine the future of that process. An urban plan is presented as a set of notions of detailed morphological and relational dimensions that generate an inertia towards a specific objective, which defines a pursued utopian scenario. The realization of this scene turns the plan into an element with a low probability of being materialized while maintaining the accuracy of what was planned. Therefore, altertopia is necessarily born at the same time as utopia: the altertopia is the remaining infinite universe of alternatives to the plan. This relationship among milestones and the implication they have in the constant formation of the city process is evidenced in the La Paz–Bidebieta constellation, paradigmatic case study due to its genesis of tabula rasa in an autarchic context, as a peripheral neighbourhood of Donostia–San Sebastián promoted by the OSH in the 1960s, endorsing the fidelity to the Partial Plan by it was originated.

This paper outlines the development phases of a wave-driven Helicon Plasma Thruster for cutting-edge Low Earth Orbit (LEO) constellations. The two-stage ambipolar electric propulsion (EP) system combines the efficient ionization of an ultra-compact helicon reactor with plasma acceleration based on an ambipolar electric field provided by a magnetic nozzle. This paper reveals maturation challenges associated with an emerging EP system in the hundreds-watt class, followed by outlook strategies. A 3 cm diameter helicon reactor was operated using argon gas under a time-modulated RF power envelope ranging from 250 W to 500 W with a fixed magnetic field strength of 400 G. Magnetically enhanced inductively coupled plasma reactor characteristics based on half-wavelength right helical and Nagoya Type III antennas under capacitive (E-mode), inductive (W-mode), and wave coupling (W-mode) were systematically investigated based on Optical Emission Spectroscopy. The operation characteristics of a wave-heated reactor based on helicon configuration were investigated as a function of different operating parameters. This work demonstrates the ability of two-stage HPT using a compact helicon reactor and a cusped magnetic field to outperform today’s LEO spacecraft propulsion.

The Cislunar economy is thriving with innovative space systems and operation techniques to enhance and uplift the traditional approaches significantly. This paper brings about an approach for sustainable small satellite constellations to retain autonomy for long-term missions in the Cislunar space. The methodology presented is to align the hybrid model of the constellation for Earth and Moon as an integral portion of the Cislunar operations. These hybrid constellations can provide a breakthrough in optimally utilizing the Cislunar space to efficiently deploy prominent missions to be operated and avoid conjunction or collisions forming additional debris. Flower and walker constellation patterns have been combined to form a well-defined orientation for these small satellites to operate and deliver the tasks satisfying the mission objectives. The autonomous multi-parametric analysis for each constellation based in Earth and Moon’s environment has been attained with due consideration to local environments. Specifically, the Solar Radiation Pressure (SRP) is a critical constraint in Cislunar operations and is observed during simulations. These are supported by conjunction analysis using the Monte Carlo technique and also the effect of the SRP on the operating small satellites in real-time scenarios. This is followed by the observed conclusions and the way forward in this fiercely competent Cislunar operation.

With the development of the space industry, LEO simulation platforms are increasingly important. Prior work mainly focused on the dynamics of constellation topology, routing algorithms against the topological motion, and the behavior of LEO constellation networks, but neglected real-time and completeness properties. In our work, we design a real-time and complete network simulation framework, named LEOCN, that is more meaningful and detailed for researchers than previous work on LEO satellite constellation simulations. LEOCN is supported by Linux System, which makes the framework more realistic and relieves the computational burden. Meanwhile, LEOCN deeply considers topology and routing algorithms, visualization, satellite mobility, communication protocols, and network traffic problems. On LEOCN, we can deploy routing algorithm experiments via SDN. We evaluate the performance of LEOCN in large-scale constellation scenarios, and the results demonstrate the superiority of the real-time and complete network simulation framework. [ABSTRACT FROM AUTHOR]

The contribution deals with the typewritten concrete poetry of the intermedia artist Milan Adamčiak (1946 – 2017), which was created in the second half of the 1960s. It focuses on two characteristic forms of concrete poetry: verbal and sentence constellations. It observes how the principle of seriality is applied to these text-image compositions. Seriality, as a key compositional and meaning-generating principle, is particularly associated with repetition and variation. In the context of verbal constellations, the article emphasizes the function of visual composition in dealing with a word extracted from linguistic syntax. In sentence constellations, it concentrates on the metacritical function of these forms, specified in the form of a critique of language as a means of communication and an instrument of power. Adamčiak’s repetitive-variation manipulation of linguistic material represents the application of visual techniques to literary creation. The contribution also points out the intermedia character of Adamčiak’s concrete poetry, highlights its parallels and connections with Czech experimental poetry, and selectively considers the socio-political circumstances of the time. [ABSTRACT FROM AUTHOR]

With the development of the space industry, LEO simulation platforms are increasingly important. Prior work mainly focused on the dynamics of constellation topology, routing algorithms against the topological motion, and the behavior of LEO constellation networks, but neglected real-time and completeness properties. In our work, we design a real-time and complete network simulation framework, named LEOCN, that is more meaningful and detailed for researchers than previous work on LEO satellite constellation simulations. LEOCN is supported by Linux System, which makes the framework more realistic and relieves the computational burden. Meanwhile, LEOCN deeply considers topology and routing algorithms, visualization, satellite mobility, communication protocols, and network traffic problems. On LEOCN, we can deploy routing algorithm experiments via SDN. We evaluate the performance of LEOCN in large-scale constellation scenarios, and the results demonstrate the superiority of the real-time and complete network simulation framework. [ABSTRACT FROM AUTHOR]

The use of electro-optical imaging system for commercial, military, or surveillance missions, as well as space scientific missions, dates back to the first successful operation aboard the US Explorer-6 spacecraft, which was the first spacecraft to capture low-resolution images of the Earth's surface, and the Luna-3 space probe, which was the first spacecraft to send images of the lunar far side, in 1959. The technology underlying EO system have evolved over time, with advances in optics, electronics, and materials science leading to the development of more sophisticated and capable imaging sensors. Furthermore, the technological advances in sensors, optics, mechanics, material, signal and image processing algorithms have allowed EO payloads to become smaller, lighter, and more efficient while still providing high-quality imagery. Over 840 small spacecraft weighing less than 500 kg were launched, with 80% in the constellation segment and 20% as monolithic satellites (i.e., single spacecraft equipped with an electro-optical imaging instrument launched into space for various missions). In this paper, the electro-optical imaging systems of these spacecraft were reviewed using data from a variety of sources, including peer-reviewed journal publications, conference proceedings, mission webpages, and other publicly available satellite databases. Furthermore, the technological and commercial expansion of small spacecraft (< 500 kg) equipped with electro-optical imaging systems, as well as EO-COTS parametric performance values such as GSD, spectral range, field of view, and sensor type, are discussed through 2023, divided by spacecraft type: SSO satellites, Small spacecraft constellation, Deep space spacecraft, and EO commercialization. • The evolution of electro-optical imaging system. • Small spacecraft missions equipped with EO sensors. • Constellation of small satellite missions can provide comparable capability. • The advantages of an EO-based deep space spacecraft mission. • The main factors driving the market trend toward small spacecraft optical payload. [ABSTRACT FROM AUTHOR]

Abstract Automatic modulation classification plays a critical role in the intelligent reception of unknown wireless signals. In practice, the dynamic wireless environment brings a great challenge, and the actual test model is inconsistent with the training model. Therefore, aiming at the problem of noise mismatch, this paper proposes a new modulation classification method based on KD-GoogLeNet and Squeeze-Excitation (KD-GSENet). Using the k-dimensional tree, the complex wireless signals are converted into color images rather than normal constellations, which can enhance the classification features. Considering the attention block has the inherent advantage of assigning more weights to important features, this paper further uses it to improve the GoogLeNet. Finally, extensive experiments are presented including Gaussian noise, non-Gaussian noise, and the scenarios of noise mismatch. Numerical results verify the superior classification performance of the proposed KD-GSENet under different scenarios.

The development of small spacecrafts requires the solution of a number of new scientific and technical problems. The main directions of research and development of the Baltic State Technical University «VOENMEH» named after D. F .Ustinov on solving the problems of creating small spacecrafts, deploying and maintaining orbital constellations of the small spacecrafts, and managing orbital groupings are presented. Some results of these works are presented, in particular, the preliminary design of a small space tug with an innovative two-component gas rocket engine powered by oxygen and hydrogen, operated in conjunction with an ultralight class launch vehicle. Small space tug solves the problems of interorbital transportation of the small spacecrafts. It has no analogues in the russian rocket and space technology. Variants of ballistically coupled groups of small spacecrafts are presented that can ensure the formation of a stable quasi-stationary distributed aperture in orbits in order to increase the efficiency of space communication systems and remote sensing of the Earth. The development of an innovative actuator – a two-axis rotary platform based on piezoelectric drives is presented. This device significantly exceeds traditional electromechanical devices based on electric drives in terms of weight, dimensions, dynamic characteristics and other parameters. The variants of the application of this rotary platform as part of the service and target systems of the small spacecrafts are considered. It is shown how this can provide a significant increase in the tactical and technical characteristics of the small spacecrafts.

The detection and observation of space debris in Low Earth Orbit is generally carried out through the use of ground based radars and telescopes. These instruments allow for a precise reconstruction of the space debris trajectories, and therefore represent a key asset for planning avoidance maneuvers when threats of collisions are predicted. The recent deployment of mega-constellations, with the consequent increase of the number of satellites, imposes new challenges in terms of simultaneous tracking capability and readiness of the current space situational awareness systems. This adds to the current need to track small and dull objects to further mitigate the probability of triggering cascade collisions. However, ground based observations are limited due to their intrinsic sensibility to atmospheric refraction, their diurnal inoperability and their dependence on meteorological hazards. This paper proposes to study the feasibility and the benefits of a potential deployment of a constellation of CubeSats in Low Earth Orbit, to acquire optical observations of space debris with enhanced accuracy, as part of the ORCA mission: Orbit Refinement for Collision Avoidance. Here, the focus is on the optical design of the payload instrument to be integrated onboard of the orbiting platforms. The study trades-off the current state-of-art of optical detection technologies, by assessing their performance against a set of specific requirements: (a) the minimization of the uncertainty associated to the image resolution; (b) a field of view that maximizes the extent of the monitored area; (c) an optimal exposure time to avoid under or overexposure of the image; (d) minimization of the effects of light diffraction and above all, (e) the maximization of the signal to noise ratio to detect the smallest and dullest objects possible. Several configurations of optical systems are then chosen as suitable for the ORCA constellation, also considering the system design implications of its integration into a CubeSat, such as size requirements. Commercial Off-The-Shelf hardware are explored and performances of the optical system are evaluated through numerical simulations in order to estimate the detectable sizes of space debris while taking into account their potential distances from the sensor. This paper concludes with estimates of the impact of the ORCA mission on space situational awareness for decades to come. • We defined requirements for an optical system for space debris surveillance. • We formulated conditions allowing detection of space debris from optical images. • We explored feasible design of optical systems for a CubeSat size implementation. • We compared our results with available commercial-off-the-shelf optical systems. [ABSTRACT FROM AUTHOR]

The cooperative orbit determination (OD) using inertial inter-spacecraft measurements is of great value for the constellation. Previous studies concluded that the cooperative OD system in the two-body dynamics is observable using the inertial angle measurement. This paper performs an observability analysis for the inertial angle-only cooperative OD system based on the observability matrix (OM), and finds that the previous conclusions do not hold for some special configurations. Eight special configurations are proposed, and for each configuration, the unobservable orbit elements are analytically revealed by analyzing the linear relationship among different columns of the OM. Moreover, a method of improving the observability of the two-spacecraft system is proposed by adding another spacecraft. An extended Kalman filter is employed to numerically illustrate the observability of the proposed special configurations and to show the relationship between the observability and the convergence ratio of estimations. Monte Carlo simulations show that the convergence ratios of the observable orbit elements and state combinations are higher than 97%, while convergence ratios of the unobservable states are lower than 70%. With one non-planar elliptic orbit added, all the elements of the three-spacecraft system are observable, and the estimated errors converge within 6 h. The results found in this paper can provide a reference for the design and management of the constellation. • Observability analysis for the angle-only cooperative OD is performed. • Eight unobservable configurations are revealed using the observability matrix. • A method of improving the observability is proposed by adding another spacecraft. [ABSTRACT FROM AUTHOR]

Satellite imagery and data collection have many advantages over other sources of soil observations. The developments in this field lead to the need of reducing cost with improving image construction methods. The concept of so-called satellite constellation accompanied by 3D vision technique may improve the coverage of a specific area. Here presented a satellite constellation conception is for a 3D reconstruction of urban areas, filling the gap of the required temporal resolution to properly monitor this contribution. Thus, a miniaturization method of space vehicles was proposed using CubeSat constellation resides at an altitude of 500 km. The number of satellites required to meet the challenges of earth observation is nine satellites. To accomplish the main goal, meeting the adequate resolution, a development study around a deployable optic camera is presented for a 3D reconstruction. [ABSTRACT FROM AUTHOR]

Deep-learning-based automatic modulation recognition (AMR) has recently attracted significant interest due to its high recognition accuracy and the lack of a need to manually set classification standards. However, it is extremely challenging to achieve a high recognition accuracy in increasingly complex channel environments and balance the complexity. To address this issue, we propose a multi-modal AMR neural network model with SNR segmentation called M-LSCANet, which integrates an SNR segmentation strategy, lightweight residual stacks, skip connections, and an attention mechanism. In the proposed model, we use time domain I/Q data and constellation diagram data only in medium and high signal-to-noise (SNR) regions to jointly extract the signal features. But for the low SNR region, only I/Q signals are used. This is because constellation diagrams are very recognizable in the medium and high SNRs, which is conducive to distinguishing high-order modulation. However, in the low SNR region, excessive similarity and the blurring of constellations caused by heavy noise will seriously interfere with modulation recognition, resulting in performance loss. Remarkably, the proposed method uses lightweight residuals stacks and rich ski connections, so that more initial information is retained to learn the constellation diagram feature information and extract the time domain features from shallow to deep, but with a moderate complexity. Additionally, after feature fusion, we adopt the convolution block attention module (CBAM) to reweigh both the channel and spatial domains, further improving the model's ability to mine signal characteristics. As a result, the proposed approach significantly improves the overall recognition accuracy. The experimental results on the RadioML 2016.10B public dataset, with SNR ranging from −20 dB to 18 dB, show that the proposed M-LSCANet outperforms existing methods in terms of classification accuracy, achieving 93.4% and 95.8% at 0 dB and 12 dB, respectively, which are improvements of 2.7% and 2.0% compared to TMRN-GLU. Moreover, the proposed model exhibits a moderate parameter number compared to state-of-the-art methods. [ABSTRACT FROM AUTHOR]

In some geographically challenging areas (such as deserts, seas, and forests) where direct connectivity to a terrestrial network is difficult, space communication is the only option. In these remote locations, Internet of Space Things (IoST) applications can also be used successfully. In this paper, the proposed payload for IoST applications demonstrates how an Automatic Identification System (AIS) and a fire detection system can be used effectively. A space mission based on efficient and low-cost communication can use a constellation of nanosatellites to better meet this need. These two applications, which use a constellation of nanosatellites, can provide relevant university-level data in several countries as an effective policy for the transfer of space technology in an educational initiative project. To enhance educational participation and interest in space technology, this paper shares the lessons learned from the project feasibility study based on an in-depth design of a nanosatellite with several analyses (data budget, link budget, power budget, and lifetime estimation). Lastly, this paper highlights by experiments the development and application of a cost-effective sensor node for fire detection and the use of GPS to enable AIS capabilities in the IoST framework. [ABSTRACT FROM AUTHOR]

Automatic modulation classification plays a critical role in the intelligent reception of unknown wireless signals. In practice, the dynamic wireless environment brings a great challenge, and the actual test model is inconsistent with the training model. Therefore, aiming at the problem of noise mismatch, this paper proposes a new modulation classification method based on KD-GoogLeNet and Squeeze-Excitation (KD-GSENet). Using the k-dimensional tree, the complex wireless signals are converted into color images rather than normal constellations, which can enhance the classification features. Considering the attention block has the inherent advantage of assigning more weights to important features, this paper further uses it to improve the GoogLeNet. Finally, extensive experiments are presented including Gaussian noise, non-Gaussian noise, and the scenarios of noise mismatch. Numerical results verify the superior classification performance of the proposed KD-GSENet under different scenarios. [ABSTRACT FROM AUTHOR]

Depuis trois ans, mes collègues et moi-même animons un séminaire d'épistémologie de la psychiatrie. C'est sur cette expérience commune en plus de chacune des nôtres (cliniciens, philosophes...) que nous sommes fondés à aborder la question de l'ouverture en psychiatrie. À quelles fins ouvrir la psychiatrie ? Quelle idée du progrès poursuit-on ? Nous avons, au cours de ses années de travail, eu la chance de pouvoir tenir un fil qui lie les très diverses contributions qui nous ont été apportées, tant du côté de l'histoire de notre discipline, que de la psychanalyse, de la philosophie des sciences, de l'anthropologie, des savoirs expérientiels. Nous faisons le constat que la psychiatrie n'existe dans sa définition complète et satisfaisante que dans le débat que nous avons fait vivre avec ceux qui ont quelque chose à en dire depuis une place qu'on aurait pu juger extérieure : historien, psychanalyste, anthropologue, philosophe... Si un corpus théorique se croit suffisant pour dire la chose psychique, il a tort; pourtant si on verse dans la psychiatrie intégrative on s'éloigne autrement, mais irrémédiablement de la vérité scientifique sur notre objet. Nous proposons donc une nouvelle manière de décrire la pratique de la psychiatrie : inspirés par la psychothérapie institutionnelle qui propose de réunir les transferts de chacun des participant aux soins en en respectant l'intégrité subjective, nous posons qu'il est possible de réunir une constellation épistémique pour chacun de nos efforts de soin, réunissant les savoirs nécessaires à celui-ci sans les dénaturer ni leur faire perdre leur radicalité. For three years, my colleagues and I have been leading a seminar on the epistemology of psychiatry. Based on this shared experience, in addition to our own personal experiences (as clinicians, philosophers, etc.), we tackle the question of openness in psychiatry. What does psychiatry open up to ? What idea of progress are we pursuing ? We have, during these years of work, been lucky enough to be able to grasp a common thread that links the very diverse contributions that have been presented in our seminar, both in terms of the history of our discipline, as well as psychoanalysis, the philosophy of science, anthropology, experiential knowledge. We note that psychiatry exists in its complete and satisfactory definition only in the debate that we have facilitated with those who have something to say about it from a place that could be judged external: historian, psychoanalyst, anthropologist, philosopher.. If a theoretical corpus believes itself sufficient to speak about the psychic thing, it is wrong; however, if we veer into integrative psychiatry we move away differently, but irremediably, from the scientific truth of our object. We therefore explain a new way of describing the practice of psychiatry: inspired by institutional psychotherapy, which proposes to bring together the transferences of each of the participants in care while respecting subjective integrity, we posit that it is possible to bring together an epistemic constellation for each of our caregiving efforts, bringing together the knowledges necessary for this without distorting them or causing them to lose their radicality. [ABSTRACT FROM AUTHOR]

The notion of Chineseness has been contested and negotiated for decades due to the cultural and geopolitical contingencies and disjunctures of disparate lived experiences between the mainland and cross-border Chinese communities. Under these circumstances, the polemic has never ceased to be settled, with the major focus on the tensions between state-led nationalism and diasporic transnationalism. Despite the fact that prior studies have proposed a variety of approaches to avoid any effort at blanket integration or radical exclusion, both sides are inevitably bound inside the habitualized ideological apparatus, locking the discussion in an endless loop of essentialism. To transcend the epistemic gridlock, this article, based on Tash Aw's selected literary works, postulates an experimental praxis for rewriting composite Chineseness via metatextual reconstruction. Through the strategic juxtaposition and comparison of fluidly correlated narratives, the structural flaw built within the theoretical terrain of Chineseness would possibly be bridged, which foreshadows a constellation of multilayered Chineseness to come. [ABSTRACT FROM AUTHOR]

Copyright of Constelaciones (2340-177X) is the property of Fundacion Universitaria San Pablo - CEU and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The increasing amount of space debris poses a major threat to the security of space assets. The timely acquisition of space debris orbital data through observations is essential. We established a mathematical model of optical satellite constellations for space debris observation, designed a high-quality constellation configuration, and designed a space debris tracking observation scheduling algorithm. These tools can realize the efficient networking of space debris from a large number of optical satellite observation facilities. We designed a constellation consisting of more than 20 low-Earth orbit (LEO) satellites, mainly dedicated to the observation of LEO space objects. According to the observation scheduling method, the satellite constellation can track and observe more than 93% of the targets every day, increase the frequency of orbital data updates, and provide support for the realization of orbital space debris cataloguing. Designing optical satellite constellations to observe space debris can help realize the advance perception of dangerous collisions, timely detect dangerous space events, make key observations about high-risk targets, greatly reduce the false alarm rate of collisions, and provide observational data support for space collisions. [ABSTRACT FROM AUTHOR]

The increasing demand for low-cost space-borne Earth observation missions has led to small satellite constellation systems development. CubeSat platforms can provide a cost-effective multiple-mission space system using state-of-the-art technology. This paper presents a new approach to CubeSat constellation design for multiple missions using a multi-objective genetic algorithm (MOGA). The CubeSat constellation system is proposed to perform multi-missions that should satisfy global Earth observation and regional disaster monitoring missions. A computational approach using a class of MOGA named non-dominated sorting genetic algorithm II is implemented to optimize the proposed system. Pareto optimal solutions are found that can minimize the number of satellites and the average revisit time (ART) for both regional and global coverage while maximizing the percentage coverage. As a result, the study validates the feasibility of implementing the CubeSat constellation design with an acceptable level of performance in terms of ART and percentage coverage. Moreover, the study demonstrates CubeSat's ability to perform a multi-missions. [ABSTRACT FROM AUTHOR]

En el actual contexto de la pandemia causada por el Covid-19, la literatura no se ha mantenido al margen. Han surgido múltiples textos literarios que encallan las experiencias, subjetividades y aporías de la actual crisis. Este trabajo tiene por objetivo describir algunos criterios teórico-metodológicos a partir de los cuales se pueda seleccionar y conformar un corpus de textos literarios que nos permita analizar e interpretar las configuraciones del núcleo traumático de la pandemia del Covid-19. Se proponen dos criterios centrales: la literatura transnacional y la constelación. En primer lugar, se enmarca a la literatura de la pandemia en una perspectiva transnacional porque el intercambio, el tránsito y la movilidad de los textos se producen material y simbólicamente por medio de la World Wide Web (www); territorio digital que imbrica y conjuga tanto lo local como lo global. En segundo término, se propone la figura de la constelación (de génesis benjaminiana) como instrumento metodológico para la construcción de un corpus, ya que posibilita encontrar nexos entre textos que usualmente no se pensarían como próximos o vinculados, facilitando encuentros improbables de textos entre culturas.________ In the current context of the pandemic caused by Covid-19, literature has not remained on the sidelines. Multiple literary texts have emerged and have stranded the experiences, subjectivities and aporias of the current crisis. This paper aims at describing some theoretical-meth-odological criteria from which to select and form a corpus of literary texts that will allow us to analyze and interpret the configurations of the traumatic core of the Covid-19 pandemic. Two central criteria are proposed: transnational literature and constellation. First, the literature of the pandemic is framed in a transnational perspective because the exchange, circulation and mobility of texts are produced materially and symbolically through the World Wide Web, turning cyberspace into a transnational space, in which the local and the global become symbiotic. Secondly, the figure of the constellation (of Benjaminian genesis) is proposed as a methodological instrument for the construction of acorpus, since it makes it possible to find links between texts that would not usually be thought of as close or linked, facilitating improbable encounters of texts between cultures.

RAMALHO-SANTOS, Irene (2022). Fernando Pessoa and the Lyric. Disquietude, Rumination, Interruption, Inspiration, Constellation. Lanham, Maryland: Lexington Books. 190 pp. [ISBN: 9781666903133].

Deciphering the genesis and evolution of the Martian polar caps can provide crucial understanding of Mars' climate system and will be a big step forward for comparative climatology of the terrestrial planets. The growing scientific interest for the exploration of Mars at high latitudes, together with the need of minimizing the resources onboard landers and rovers, motivates the need for an adequate navigation support from orbit. In the context of the ARES4SC study, we propose a novel concept based on a constellation that can support autonomous navigation of different kind of users devoted to scientific investigations of those regions. We study two constellations, that differ mainly for the semi-major axis and the inclination of the orbits, composed of 5 small satellites (based on the SmallSats design being developed in Argotec), offering dedicated coverage of the Mars polar regions. We focus on the architecture of the inter-satellite links (ISL), the key elements providing both ephemerides and time synchronization for the broadcasting of the navigation message. Our concept is based on suitably configured coherent links, able to suppress the adverse effects of on-board clock instabilities and to provide excellent range-rate accuracies between the constellation's nodes. The data quality allows attaining good positioning performance for both constellations with a largely autonomous system. Indeed, we show that ground support can be heavily reduced by employing an ISL communication architecture. Periodic synchronization of the clocks on-board the constellation nodes with terrestrial time (TT) is enabled through the main spacecraft (the mother-craft), the only element of the constellation enabling radio communication with the Earth. We report on the results of numerical simulations in different operational scenarios and show that a very high-quality orbit reconstruction can be obtained for the constellation nodes using a batch-sequential filter or a batch filter with overlapping arcs, that could be implemented on board the mother-craft, thus enabling a high level of navigation autonomy. The assessment of the achievable positioning accuracy with this concept is fundamental to evaluate the feasibility of a future positioning system providing a global coverage of the red planet. • Polar constellation of small satellites on Mars. • Provide navigation services for Martian landers, rovers, and orbiters. • Quasi-autonomous constellation ephemeris reconstruction. • Novel tracking technique for inter-satellite link. [ABSTRACT FROM AUTHOR]

As the number of non-geostationary orbit (NGSO) satellites continues to grow, interference with other communication systems, including radio astronomy systems (RASs), is becoming increasingly critical. In this study, an interference simulation framework was developed to analyse the potential impact of NGSO systems on RAS in accordance with the relevant International Telecommunication Union (ITU) regulations and recommendations. In addition to the simulation of interference generated by individual NGSO satellite systems, the framework also supports the analysis of aggregate interference from multiple NGSO satellite systems. By inputting satellite system parameters, including constellation configuration, user distribution and beam scheduling strategy, the framework is able to obtain interference probability distributions for a typical RAS ground station at different latitudes and observation directions. The simulation results provide a reference for the analysis of interference from NGSO satellite systems to RASs, and can also be used to guide the development of strategies to mitigate harmful interference to RASs. [ABSTRACT FROM AUTHOR]

In this paper, a novel concept for cooperative orbit determination (OD) using inter-spacecraft angle-only measurements is proposed. Different from the conventional cooperative OD that only estimates orbit states, the attitude of the observer spacecraft is considered by incorporating the attitude into the estimated vector. The observability of a two-spacecraft system is analyzed based on the observability matrix. Observability analysis reveals that inter-spacecraft angle-only measurements are inadequate to estimate both the attitude and the orbit states in two-body dynamics. The observability of the two-spacecraft system can be improved by considering high-order gravitational perturbation or executing an attitude maneuver on the observer spacecraft. This is the first time that we present the observability analysis and orbit estimation results for a two-spacecraft system considering attitude uncertainty for the observer. Finally, simulation results demonstrate the effectiveness of the proposed method. The results in this paper can be potentially useful for autonomous managements of a spacecraft constellation and formation. [ABSTRACT FROM AUTHOR]

Proliferated low Earth orbit constellations are becoming more common both in reality and in planning. The resilience of these constellations to the radiation effects of adverse solar weather is of interest given that some of them pass over polar regions. This paper stochastically simulates solar weather events over the course of solar cycle 25 in order to quantify radiation effects on a model of Planet Lab's Flock constellation under various design and programmatic decisions. The Flock constellation is a highly proliferated, commercial, and polar low Earth orbit earth observation architecture. Lifecycle and radiation failures are simulated along with a reconstitution system in order to quantify architectural performance as a function of constellation population. This time-based measure of performance is then used to quantify the constellation resilience and allow for programmatic and design variables to be altered in order to observe the effects on the resilience of proliferated constellations against adverse solar weather radiation effects. A sensitivity analysis is performed in order to assess which decisions most improve or degrade resilience. Broadly, the results show that commercial off the shelf components and programmatic decisions such as launch and manufacturing schedules may improve constellation resilience against adverse solar weather effects. More specifically, the results also show that commercial off the shelf components with even basic shielding levels provide high resilience to cumulative total ionizing dose effects and single event upset radiation effects. However, any further reductions to shielding would have significant impacts on single event upset rates whereas total ionizing dose would remain negligible. Furthermore, manufacturing time for Flock satellites is sufficient to maintain a resilient reconstitution strategy. Finally, results show that in order to improve the resilience afforded by a reconstitution strategy, improvements to manufacturing and launch times should be made in parallel, rather than one or the other in isolation. • COTS and programmatics may improve LEO constellation resilience to solar weather. • LEO constellations are highly resilient to even extreme solar weather radiation. • Shielding and launch times are significant for resilience to LEO solar radiation. • Manufacture and launch times should improve parallelly for constellation resilience. • Cumulative radiation in LEO is negligible, primary concern is single event effects. [ABSTRACT FROM AUTHOR]

Copyright of Lex Humana is the property of Lex Humana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)