Mission Time Research Articles

“This Book Is Your Book”: Jesuit Editorial Policy and Individual Indigenous Reading in Eighteenth-Century Paraguay

Abstract The authors underline the importance of the print Ara poru aguĭyey haba (meaning about the good use of time) for the Jesuit missions of Paraguay and the colonial Río de la Plata. Attributed to Father José Insaurralde, it is a two-volume devotional text entirely written in Guaraní that was published in Madrid in 1759 and 1760. Until now, literature has only approached the Ara poru in a superficial and external way, because it is written in a different way from the current ones. The unpublished translation of the summary and two preliminary warnings to readers reveal that it follows the structure of Ignacio de Loyola’s Spiritual Exercises. The authors of this article demonstrate that by the mid-eighteenth century, the Jesuit project was to produce an indigenous reader and devotee in the modern sense (individual reading and personal transformation).

Ocena niezawodności naprawialnego systemu z misjami okresowymi za pomocą symulacji Monte Carlo w oparciu o modułowy model drzewa niezdatności z bramkami SEQ

Phased-mission system (PMS) is the system subject to multiple, consecutive and non-overlapping tasks. Much more complicated problems will be confronted when the PMS is repairable since the repairable system could perform the multi-phases mission with more diversity requirements. Besides, various maintenance strategies will directly influence the reliability analysis procedure. Most researches investigate those repairable PMSs that carry out the multi-phases mission with deterministic phase durations, and the mission fails once the system switches from up to down. In this case, one common maintenance strategy is that failed components are repairable as long as the system keeps in up state. However, many practical systems (e.g., construction machinery, agricultural machinery) may be involved in such multi-phases mission, which has uncertain phase durations but limited by a maximum mission time, within which failed components can be unconditional repaired, and the system can be restored from down state. Comparing with the former type of repairable PMS, the latter will also concern phase durations dependence, and both the system and components included have the state bidirectional transition. This paper makes new contributions to the reliability assessment of repairable PMSs by proposing a novel SEFT-MC method. Two types of repairable PMS mentioned above are considered. In our method, a specific sequence-enforcing fault tree (SEFT) is proposed to correctly depict failure logical relationships between the system and components included. In order to transfer the graphical fault tree (no matter its size and complexity) into a modular reliability model used in Monte Carlo (MC) simulation, an improved linear algebra representation (I-LAR) approach is introduced. Finally, a numerical example including two cases corresponding to the two types of repairable PMS is presented to validate the proposed method.

Trajectory Planning of Multiple Dronecells in Vehicular Networks: A Reinforcement Learning Approach

The agility of unmanned aerial vehicles (UAVs) have been recently harnessed in developing potential solutions that provide seamless coverage for vehicles in areas with poor cellular infrastructure. In this letter, multiple UAVs are deployed to provide the needed cellular coverage to vehicles traveling with random speeds over a given highway segment. This letter minimizes the number of deployed UAVs and optimizes their trajectories to offer prevalent communication coverage to all vehicles crossing the highway segment while saving energy consumption of the UAVs. Due to varying traffic conditions on the highway, a reinforcement learning approach is utilized to govern the number of needed UAVs and their trajectories to serve the existing and newly arriving vehicles. Numerical results demonstrate the effectiveness of the proposed design and show that during the mission time, a minimum number of UAVs adapt their velocities in order to cover the vehicles.

Improvement in energy conversion for unmanned aerial vehicle charging pad

<span style="font-size: 9pt; font-family: 'Times New Roman', serif;">An efficient charging station is a necessity for Unmanned Aerial Vehicle (UAV) systems. However, if that implementation adds more complexity and onboard weight, then that exercise becomes a burden rather than a benefit since UAV's engineers aim to improve efficiency by reducing the energy consumed by the software and hardware of the complete aeronautical system. This article recommends a fully automatic contact charging station for UAVs, which can charge UAVs and thus resolve flight endurance restrictions of the UAV. The ground station consists of square copper plates that are positively and negatively polarized successively in a chessboard with particular sizes to guarantee electric contact at the landing. The design methodology used with the loading station takes into account the differences in UAV orientation once the platform has landed. In addition, this innovation uses independent charging after touchdown. Thus, this technology relaxes common flight times and help to enhance general mission times. This paper presents a unique charging platform in a “chessboard” configuration, which is devised as an interconnecting interface to facilitate the charging process and overcome inaccuracies with the landing. The solution devised in this research requires few components and presents two power source options (solar & mains power). Additionally, this work presents, to the best of our knowledge, a uniquely innovative recharging landing platform, which incidentally requires no additional software or changes to the UAV’s onboard software settings</span><span style="font-size: 9pt; font-family: Arial, sans-serif;">.</span>

Statistical inference for constant‐stress accelerated life tests with dependent competing risks from Marshall‐Olkin bivariate exponential distribution

AbstractThis paper considers a constant‐stress accelerated dependent competing risks model under Type‐II censoring. The dependent structure between competing risks is modeled by a Marshall‐Olkin bivariate exponential distribution, and the accelerated model is described by the power rule model. The point and interval estimation of the model parameters and the reliability function under the normal usage condition at mission time are obtained by using the maximum likelihood estimation method and the bootstrap sampling technique. Moreover, the pivotal quantities based estimation are adopted to estimate the model parameters and the generalized confidence intervals. As a comparison, we also consider the Bayes estimation and the highest posterior density credible intervals for the model parameters based on conjugate priors and importance sampling method, respectively. To illustrate the proposed methodology, a Monte Carlo simulation is used to study the performances of different estimation methods. Finally, a dataset is analyzed for illustrative purpose and a comparison with the original results is also given.

Licensing Framework of CANDU Reactors in Canada, and Alternatives for Crediting EME in Safety Analysis

This paper summarizes the existing framework of safety analysis and licensing of CANDU reactors in Canada, established by the Canadian Nuclear Safety Commission (CNSC), and explores enhancements to better capture and implement lessons learned from the Fukushima accident, in conducting nuclear safety analysis for the existing and new reactors. This paper compares the Canadian regulatory requirements with other international nuclear regulatory guidelines, in terms of dealing with Beyond Design Basis Accidents (BDBA) and Severe Accidents, and also reviews the past and present event classification principles in safety analysis, set by the CNSC. The CNSC have published regulatory documents and technical papers outlining the challenges to be addressed with respect to implementations of the Design Extension Conditions (DEC). The DEC concept has interfaces with the other safety concepts such as Defence-in-Depth in Deterministic Safety Analysis (DSA) of the Design Basis Accidents (DBA), and Best-Estimation in Probabilistic Safety Assessment (PSA) of Beyond Design Basis Accidents (BDBA). This paper explores the current requirements and the principles of the regulatory framework in Canada, and compare it with alternative practical solutions, such as using portable/mobile Emergency Mitigating Equipment (EME) primarily for mitigation of Severe Accidents consequences, versus preventing them. Systematic examination of CANDU PSA results shows, crediting mobile EME in Level 1 PSA accident sequences have challenges. Although, adding another layer of redundancy to backup support systems (electrical power, cooling water and air) further reduces the frequency of Severe Core Damage (SCD), portable EME can only have a short-term mission time, and the main benefit in using crediting them in Level 1 PSA, is to delay the consequences. This paper proposes a thorough review of PSA before allocating EME to AIM/EOP or SAMG, with the objective of maintaining a balance between prevention and mitigation of severe core damage and large release. Maintaining this balance is paramount and instrumental to public safety. Instead of focusing on reducing the “probability” of accidents by crediting every available EME in Level 1 PSA, an alternative would present a better balance between prevention and mitigation of accidents.

A Hybrid Link Reliability Model for Estimating Path Reliability of Mobile Ad Hoc Network

Abstract Mobile ad hoc networks includes self-sustaining mobile nodes that are self-making with no predefined foundation and buildup associations amongst themselves to develop exceptionally powerful topologies due to the nodes mobility in the network. Therefore, due to mobility of the nodes the wireless links may establish (disestablish) implying that the probability of successful communication increases (decreases). Most of the researchers have observed the network performance using binary model of communication links based on Euclidean distance between nodes and the radio range of the mobile nodes i.e., a free space model or line of sight model. In general, signal can reach the destination through different paths and in such cases the signal strength decreases between nodes due to various atmospheric effects such as noise, fading or interference as the distance increases. In this paper, the proposed methodology uses the free space two ray ground propagation model to determine the connectivity of the network during mission time, which helps in determining the network performance (average hop count and path reliability) of the network through simulations in MATLAB. The obtained results shows that the reliability of a homogeneous mobile ad hoc network reduces because of propagation of the signals. Though the reliability values are less, the network is still reliable and it gives an idea for the user to deploy the mobile ad hoc network in a suitable terrains.

Trajectory Optimization for First Human Asteroid Exploration Mission

After the successful completion of robotic expeditions on Mars, an ultimate goal was set for space fairing nations and agencies around the world to send astronauts to Mars by 2030. Unfortunately, a mission to Mars would last upwards for years meanwhile several asteroids fly close to the Earth. A manned trip to an asteroid would be a valuable stepping stone towards a manned mission to Mars, as the mission time can be reduced to a few months round-trip. In addition to gaining experience with manned travel through deep space, a mission to an asteroid would provide experience overcoming a unique challenge of rendezvousing with a foreign object in microgravity. Since most of the known asteroids that are close enough to Earth to be viable targets are less than 300 m in diameter, chances are the selected asteroid will not have a significant gravitational field. Near Earth Asteroids (NEAs) have orbits that bring them into close proximity with Earth’s orbit making them both a unique hazard to life on Earth and a unique opportunity for science and exploration. A specific case study was therefore undertaken to shortlist such NEAs that are accessible for round-trip human missions using heavy lift launch architecture. A fully parameterized, highly efficient algorithm is developed using MATLAB to accomplish this. Using this algorithm a family of NEA is reviewed, several candidate asteroids are shortlisted for potential exploration and a final selection of asteroid 1999 AO10 is made followed by a specific mission trajectory design and selection to this asteroid, accounting for mission requirements and constraints. The astrodynamic components of a manned mission to NEA 1999 AO10 are also described in this study. Beginning with a launch, we will walk through preliminary trajectory optimization using Lambert’s problem and patched conics. Once the ideal trajectory is designed, the study will be extended to include abort scenarios.

Анализ динамики перелета космического мусоросборщика из плоскости своей орбиты в плоскость орбиты фрагмента мусора

A space debris collector and a debris fragment move along random noncoplanar orbits ranging from 400 to 2000 km in height. The space collector leaves the base station, transfers into the orbital plane of a debris fragment, aligns itself with and approaches the fragment, grabs it and returns to the base station. The execution time of the flight mission is 24 hours. This paper examines only the stage when the debris collector transfers from its orbital plane to the fragment’s orbital plane. Dampening is provided by repeated activation of a cruise propulsion unit with the thrust of no less than 20000 N and the fuel specific impulse of no less than 15000 m/s. An analysis of dynamics of the orbital flight is performed by numerically integrating the equations of orbital movement of the debris collector and the debris fragment using the fourth order Runge-Kutta methods. The change of the scalar product sign of the vector of the orbit area integral of the debris fragment and the radius-vector of the debris collector is the criterion for intersecting the final orbit plane. Fuel depletion and the nonsphericity of the Earth’s gravitational field in the second zonal harmonic are taken into account, and an example of the calculations is given. Convergence estimates for the integration procedure with regard to the final orbit inclination relative to the orbit’s eccentricity are provided.

A hierarchical parallel evolutionary algorithm of distributed and multi-threaded two-level structure for multi-satellite task planning

The aim of multi-satellite task planning is to study how to distribute limited resources of satellites and payloads and execution time for observation missions to be completed within a limited set of available satellites so as to best satisfy the observational demand. Aiming at the shortcomings of the current study on multi-satellite task planning, this paper proposes a hierarchical parallel evolution algorithm framework which is based on a distributed and multi-threaded two-level structure. It adopts parallel communication flow and task distribution strategy of multi-machine, multi-core and two-level structure. The distributed parallel evolution model work among multi-machines, whereas the multi-threaded parallel evolution model work among multi-cores to reduce the communication overhead of the parallel system while maintaining the global optimisation of the algorithm. The result of the experiment showed that the multi-satellite task planning evolutionary optimisation model established in the paper is effective. Subsequently, it was proven that the hierarchical parallel-evolving algorithm proposed by the paper can greatly cut down the time consumed for the evolution and improve the algorithm solving efficiency, which can effectively solve both the multi-satellite task planning issue and optimisation problems in other fields. It is thus of important use value.

Kult Trzygława w Szczecinie lat 20. XII stulecia. Między monolatrią a „dwuwiarą”

The cult of Triglav in the Polabian-Pomeranian territory in the 12th century confirms an evolution of the religious system of the local Slavic communities towards monolatry, largely affected by confrontation as well as a cultural dialogue with the Christian culture. At first, at the time of the Pomeranian missions of Saint Otto of Bamberg in the 1120s, attempts at suppressing the cult did not bring about long-term effects. However, a wave of the so-called pagan reaction led to some sort of a compromise made in Szczecin, leading to official coexistence of the cult of Triglav and the newly introduced cult of Jesus Christ. From the point of view of mythology, the competences of the two divine figures turn out to be convergent and universal, yet still, as part of the Szczecin “religious dualism”, no attempt was made to identify them (following the rule of interpretatio Slavica of the elements of Christianity). The belief in the autonomy of Triglav and Christ (“A German God”) was confirmed in Szczecin in the course of Otto’s evangelization which resulted in a Christian community in the city. The phenomenon of syncretism, present there until Otto’s second mission (1128), was therefore an attempt at maintaining unity in a religiously divided society following the first mission of the Apostle of Pomeranians (1124-1125).

Joint Optimization on Trajectory, Altitude, Velocity, and Link Scheduling for Minimum Mission Time in UAV-Aided Data Collection

Due to the flexibility in 3-D space and high probability of line-of-sight (LoS) in air-to-ground communications, unmanned aerial vehicles (UAVs) have been considered as means to support energy-efficient data collection. However, in emergency applications, the mission completion time should be main concerns. In this article, we propose a UAV-aided data collection design to gather data from a number of ground users (GUs). The objective is to optimize the UAV’s trajectory, altitude, velocity, and data links with GUs to minimize the total mission time. However, the difficulty lies in that the formulated time minimization problem has mutual effect with trajectory variables. To tackle this issue, we first transform the original problem equivalently to the trajectory length problem and then decompose the problem into three subproblems: 1) altitude optimization; 2) trajectory optimization; and 3) velocity and link scheduling optimization. In the altitude optimization, the aim is to maximize the transmission region of GUs which can benefit trajectory designing; then, in the trajectory optimization, we propose a segment-based trajectory optimization algorithm (STOA) to avoid repeat travel; besides, we also propose a group-based trajectory optimization algorithm (GTOA) in large-scale high-density GU deployment to relieve massive computation introduced by STOA. Then, the velocity and link scheduling optimization is modeled as a mixed-integer nonlinear programming (MINLP) and block coordinate descent (BCD) is employed to solve it. Simulations show that both STOA and GTOA achieve shorter trajectory compared with the existing algorithm and GTOA has less computational complexity; besides, the proposed time minimization design is valid by comparing to the benchmark scheme.

Creating and renewing identity and value through the use of non‐invasive archaeological methods: Mapoon unmarked graves, potential burial mounds and cemeteries project, western Cape York peninsula, Queensland

ABSTRACTIn 2010, Elders from Mapoon watched “Time Team” and saw ground‐penetrating radar (GPR) and other non‐invasive scientific methods being used to identify cultural features on archaeological sites. This led Elders to express their desire for such techniques, particularly GPR, to be brought on country to assist with documenting and protecting cultural heritage sites. This paper explores how Mapoon families have employed these techniques in archaeological settings to reconnect and reimagine specific features in their cultural landscape, as well as to explore, create and renew narratives from their interpretations of the results from the project. We also investigate the nature of Traditional Owner interactions with these technologies in archaeological settings to understand their impact on how cultural identity and value are recreated and renewed, on “caring for country” programmes, and on modernising culturally appropriate forms of engagement with ancestors’ remains. We apply these findings to a discussion of how Mapoon people think about their cultural history, identity and connections to country, particularly in relation to mortuary practices and settlement patterns from pre‐contact to the “mission time”.

RLS iOH: ExoMars Raman laser spectrometer optical head bread board to flight model design and performance evolutions

AbstractRaman Laser Spectrometer (RLS) is the Pasteur Payload instrument of the ExoMars mission that will perform Raman spectroscopy for the first time in a planetary space mission. RLS main units are: SPU (SPectrometer Unit), iOH (internal Optical Head), and ICEU (Instrument Control and Excitation Unit), that includes the laser for samples excitation purposes.The iOH focuses the excitation laser into the crushed samples (located at the ALD, Analytical Laboratory Drawer, carrousel) through the excitation path, and collects the Raman emission from the sample (collection path). Its original design presented a high laser trace reaching to the SPU detector, and although a certain level was required for instrument calibration, the found level was expected to be capable of degrading the acquired spectra confounding some Raman peaks. So, the iOH optical and opto‐mechanical designs were needed to be updated from the BB (Bread Board) to the engineering and qualification model (iOH EQM), in order to fix the desired amount of laser trace, and after the fabrication and the commitment of the commercial elements, the assembly and integration verification (AIV) process was carried out. Considering the results obtained during the EQM integration verification and the first functional tests, the RLS calibration target (CT) emission analysis, additional changes were found to be required for the Flight Model, FM.In this paper, the RLS iOH designs and functional tests evolutions for the different models are summarized, focusing on the iOH AIV process and emphasizing on the iOH performance evaluation (by using CT spectra) from the re‐design activities.

Salivary antimicrobial proteins and stress biomarkers are elevated during a 6-month mission to the International Space Station.

As the international space community plans for manned missions to Mars, spaceflight-associated immune dysregulation has been identified as a potential risk to the health and safety of the flight crew. There is a need to determine whether salivary antimicrobial proteins, which act as a first line of innate immune defense against multiple pathogens, are altered in response to long-duration (>6 mo) missions. We collected 7 consecutive days of whole and sublingual saliva samples from eight International Space Station (ISS) crewmembers and seven ground-based control subjects at nine mission time points, ~180 and ~60 days before launch (L-180/L-60), on orbit at flight days ~10 and ~90 (FD10/FD90) and ~1 day before return (R-1), and at R+0, R+18, R+33, and R+66 days after returning to Earth. We found that salivary secretory (s)IgA, lysozyme, LL-37, and the cortisol-to-dehydroepiandrosterone ratio were elevated in the ISS crew before (L-180) and during (FD10/FD90) the mission. "Rookie" crewmembers embarking on their first spaceflight mission had lower levels of salivary sIgA but increased levels of α-amylase, lysozyme, and LL-37 during and after the mission compared with the "veteran" crew who had previously flown. Latent herpesvirus reactivation was distinct to the ~6-mo mission crewmembers who performed extravehicular activity ("spacewalks"). Crewmembers who shed at least one latent virus had higher cortisol levels than those who did not shed. We conclude that long-duration spaceflight alters the concentration and/or secretion of several antimicrobial proteins in saliva, some of which are related to crewmember flight experience, biomarkers of stress, and latent viral reactivation.NEW & NOTEWORTHY Spaceflight-associated immune dysregulation may jeopardize future exploration-class missions. Salivary antimicrobial proteins act as a first line of innate immune defense. We report here that several of these proteins are elevated in astronauts during an International Space Station mission, particularly in those embarking on their first space voyage. Astronauts who shed a latent herpesvirus also had higher concentrations of salivary cortisol compared with those who did not shed. Stress-relieving countermeasures are needed to preserve immunity and prevent viral reactivation during prolonged voyages into deep space.

Selective maintenance optimization for multi-state systems considering stochastically dependent components and stochastic imperfect maintenance actions

This paper presents a selective maintenance optimization problem for complex systems composed of stochastically dependent components. The components of a complex system degrade during mission time, and their degradation states vary from perfect functioning to complete failure states. The degradation rate of each component not only depends on its intrinsic degradation but also on the state of other dependent components of the system. The proposed approach captures the two-way interactions between components through system performance rates and uses Monte Carlo simulation to compute the reliability of the system in the next operational mission. Different maintenance actions such as do-nothing, perfect, and stochastic imperfect maintenance are considered during the maintenance break to improve the reliability of the system. The selective maintenance bi-objective optimization problem is modelled considering both the expected value and variance of the system reliability as objective functions. Time and budget are considered as constraints for finding the optimal maintenance strategy. Two illustrative examples are provided for a better understanding of the proposed approach and for demonstrating its effectiveness.

Lao People’s Democratic Republic

At the request of the Bank of Lao, and in continuation of the FIRST TA project, this TA report provides advice towards implementing risk-based supervision (RBS). The BoL is in the process of implementing its risk-based approach to supervision to make the banking system more stable and sounder. This mission looked at the full cycle of onsite and offsite supervision process and provided advice related to applying the RBS manual, drafting and utilizing Institution Profile (IP) and Risk Assessment Summary (RAS), writing an effective examination report, the use of a risk-based approach to internal systemic reporting, and developing a supervisory response framework. The bulk of the mission time was spent on formal hands-on training sessions. During the mission, training was provided to BSD staff in small group discussions, and a more formal seminar was organized for all offsite and onsite BSD staff, which focused on reviewing the underlying RBS concepts and the elements of RBS manuals.

Initial orbit results from the TUBiX20 platform

Technische Universität Berlin has been active in the field of small satellites for more than 25 years and has successfully developed, built and operated 21 satellites to date. One of the recent developments of the university is TUBiX20, a highly modular microsatellite platform that was designed to support various different mission types. At the moment, three missions of Technische Universität Berlin are based on TUBiX20, namely TechnoSat, TUBIN, and QUEEN. Launched in July 2017, TechnoSat is the first mission to demonstrate the TUBiX20 platform in orbit. TechnoSat's mission is the demonstration of seven technology payloads that include an S-band transmitter and a reaction wheel system. This paper presents initial orbit results of the TechnoSat mission, focusing on the payloads relevant for future TUBiX20 missions. Here, the evolution of the experiments towards increasing complexity from the commissioning phase into manoeuvres that combine the use of several payloads underlines the platform's versatility. Furthermore, a quick adaptation of payloads like the S-band transmitter and the reaction wheel system into regular operations was possible by exploiting the platform's modular architecture. TechnoSat achieved all its mission objectives within the nominal mission time and is now used within its extended mission duration primarily to test and demonstrate capabilities for the upcoming missions.

Extending the utilization of dust protection systems using carbon nanotube embedded materials for lunar habitats for exploration missions

With the increasing interest in establishment of long duration outposts for lunar exploration, it is imperative that we overcome the challenges posed by the lunar environment. Lunar dust has proved to cause abrasion, thermal problems, wear and tear of materials exposed to the environments, making it a major challenge for surface operations, as witnessed during the Apollo missions. Rigid and flexible materials utilized for space hardware need to be protected from the dust contamination and degradation to extend their performance and life time for long duration missions on the lunar surface.This paper focuses on extending the functionality of the SPacesuit Integrated carbon nanotube Dust Ejection/Removal system (SPIcDER) to lunar habitat structures. Originally developed for spacesuits, which are flexed during operations, this technology can be readily adapted for flexible/deployable surface habitat structures. Pressurizable lunar inflatable/deployable habitats will require protection from dust contamination, in order to maintain their durability and pressure holding capacity over long duration missions.In this paper we propose extension of SPIcDER to exteriors of lunar habitat structures and review technical challenges for implementation. We also discuss aspects of manufacturability for large pieces of flexible materials, leveraging the lessons learned from small and medium scale testing of SPIcDER on spacesuit materials.

Orbital maneuvering of electric solar wind sail based on an advanced solar wind force model

The electric solar wind sail is a propulsion system that extracts the solar wind momentum for the thrust force of a spacecraft by using an interaction between solar wind protons and the electric potential structure around charged long thin conducting tethers. The system enables a spacecraft to generate a thrust force without consuming reaction mass. This paper investigates the capability of the electric solar wind sail as a propulsion system for deep space exploration missions. The shape of the conducting tether that is determined by the equilibrium of the solar wind force and centrifugal force is numerically calculated for formulating an advanced solar wind force model. The conducting tethers deviate from the ideal sail spin plane, and the maximum value of the thrust direction varies from 13∘ to 19∘. To estimate the spacecraft thrust vector, which is calculated as the sum of solar wind force vectors exerted on each tether, best-fit polynomial equations are proposed. We performed numerical simulations for a two-dimensional orbital transfer mission to investigate the capability of the electric solar wind sail. Results of numerical simulations show that the electric solar wind sail enables spacecraft to perform Earth–Venus, Earth–Mars, and Earth–Itokawa transfer missions. Additionally, this paper performs three-dimensional simulations for an Earth–Ryugu transfer mission. The electric solar wind sail achieves a more complicated orbital transfer in a reasonable mission time.