bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability Area of a Spacecraft’s Partially Invariant Centre of Mass Motion Stabilization System
Authors: Zosimovych Nickolay 
Published: August 2019

Abstract
In practice, a spacecraft’s stabilization system, which is partially invariant to the disturbing moment, is the easiest to implement. The velocity performance limitation of the control actuator has the most influence upon stability of the system among all the nonlinearities considered in the mathematical modelling. Therefore, we shall consider a model of an invariant stabilization system with due regard to nonlinearity. For the system under consideration, it is possible to construct lines of equal values of the auto oscillation amplitude in a two-parameter plane. The study of the stability of the proposed partially invariant stabilization system revealed that it is possible to ensure sufficient stability margins in the system under consideration by choosing parameters for the stabilization controller. At the same time, it allows to provide high quality of the transition process.
Study on the Effects of Atmospheric Parameters on Space Vehicle Design
Authors: Peng-fei Guo , Fei Wang-hua , Xiao Cun-ying 
Published: August 2019

Abstract
For the space vehicle flying in the airspace and near-space, the structure safety and attitude control ability are related to the surrounding atmosphere. The distribution characteristics of atmospheric parameters, including temperature, pressure, density and wind field should be studied based on the data statistics. In this article, the spatiotemporal distribution characteristics and measurement methods of atmospheric parameters are summarized, and the effects of atmospheric parameters on the engineering design of ballistic trajectory, propulsion system, aero-thermal heating, and attitude control system are provided. These results have considerable significance in the space vehicle general design.
Review on the Development of Satellite Formation and Collision Avoidance Technology
Authors: Hongqiang Sun , Zhanyue Zhang , Yiwen Hu 
Published: August 2019

Abstract
Formation satellites have a very broad application prospect in many aspects due to the characteristics of unlimited baselines, multi-satellites cooperative working, flexible control and strong survivability, such as distributed radar, electronic reconnaissance, three-dimensional imaging, regional navigation and positioning. In the aspect of avoiding space debris collision, the maneuvering avoidance for a single satellite is often adopted, but there are few studies on the coordinated avoidance of formation satellites. This paper introduces the concept and research status of formation satellites, and lists the common formation satellites in the world, then introduces collision warning technologies and collision geometry relation determination of formation satellites, including BOX regional warning method and collision probability warning method. In addition, the strategies of satellite evasive maneuvering are analysed, and various maneuver strategies on different purposes are introduced. Finally, analysing and comparing the research status on debris collision avoidance of formation satellites, a method to keep the working efficiency of formation satellites while maneuvering is put forward.
Assembly Method for Satellite Propulsion System based on HoloLens
Authors: Zhang Wei , Zhang Jie , Chen Huajun , Zhang Bin , Liu Feng , Zhao Jun 
Published: August 2019

Abstract
As the satellite design changes from the traditional 2D mode to the 3D digital mode, the satellite assembly also enters the 3D assembly mode. An effective and accurate propulsion system assembly information transmission method from designers to operators is not formed, in the process of complex propulsion assembly, operators need to frequently confirm status back and forth between satellite and computer stations, and accidents with incorrect polarity in component installation often occur. In order to improve efficiency and quality of satellite propulsion system installation, a system based on HoloLens is designed. The successful application of this system provides a new solution for satellite propulsion system installation and marks a new step in the digital assembly capacity.
Adaptive Backstepping Sliding Mode Fault Tolerant Control for Satellite Attitude under Actuator Faults
Authors: Huo Junhai , Meng Tao , Jin Zhonghe 
Published: August 2019

Abstract
Modern spacecraft missions place stringent performance requirements on the reliability and stability of spacecraft attitude control system. However, during long-term in-orbit mission, actuators may suffer faults. In this paper, we proposed an adaptive fault tolerant control law for attitude control under actuator failures and external disturbances. Firstly, the attitude dynamic model under actuator faults and attitude kinematics are described. Then, in order to solve the attitude control problem under actuator faults and external disturbances, an adaptive backstepping sliding mode fault tolerant control scheme is designed. According to Lyapunov theory, the closed-loop system is proved to be globally asymptotically stable. Finally, the numerical simulation results demonstrate that the proposed adaptive controller can achieve anticipative attitude control performance, fault information estimation and well fault-tolerant capability.
Use of Tetrahedral Finite Element Method for Computing the Gravitation of Irregular-Shaped Asteroid
Authors: Yin Weidong , Shu Leizheng , Yu Yang , Gao Yang 
Published: August 2019

Abstract
Asteroids are one of the most important targets for deep space exploration. In previous asteroid missions, the accurate estimate of gravity has proved to have a strong influence on the design of the approach orbit and navigation strategy. The wield gravitational field of an asteroid is mainly caused by the irregular overall shape and possible heterogenous mass distribution the interior. We propose to use the finite element method to compute the gravity of irregularly shaped asteroids; this method combines the advantages of the conventional mascon method and the polyhedral method. The tetrahedral meshes can be generated following the conventional division technique. Taking asteroid 216 Kleopatra as an example, we calculate the exterior gravitational field using the above mentioned methodology. We then compare the results from the finite element method and the polyhedral method under a degenerated case, i.e., with constant density. Then, four different density distribution assumptions are given, and the gravitational fields are calculated respectively. The comparative study and the density distribution assumptions indicate that the proposed method is suitable for modeling an arbitrary asteroid with nonuniform mass distribution. This method is expected to provide reliable gravity data for the design of guidance, navigation, and control systems in future asteroid missions.
Deep Neural Networks Based Real-time Optimal Control for Lunar Landing
Authors: Zhu Lingchao , Ma Jian , Wang Shuquan 
Published: August 2019

Abstract
Recent research on deep learning control, a new control algorithm based on machine learning able to learn deep architectures, has shown excellent performance on robots and drones. With the development of intelligent control like deep learning and reinforcement learning, accuracy, real-time, adaptability, robustness and autonomy of control algorithm have been achieved by the intelligent controls. Traditional control methods have difficulties to achieve nice performance in complex situations. Deep learning offers powerful algorithms to real-time search near-optimal controllers of lunar landing spacecraft with nonlinear dynamics. In terms of lunar landing control system, deep architectures offer the possibility to get an approximate solution of co-state equation without time-consuming iterative process. Furthermore, real-time optimal thrust during lunar landing may be derived directly through deep neural networks. As a single infrastructure for machine learning in both production and research, TensorFlow is chosen for training the deep artificial neural networks in this paper. Numerical simulations demonstrate the effectiveness of deep neural networks. The results of deep neural networks based optimal control are contrasted with traditional optimal algorithm, whose main idea is to track the pre-designed optimal trajectory by ground station. This research provides an effective approach to cope with the lunar landing problem.
Study on the Determination of Attitudes and Orbits of Micro-satellites only by 3-axis Magnetometer
Authors: Jang MyongChol 
Published: August 2019

Abstract
This paper explains a method to determine the attitude and orbit only using onboard magnetometer. This method, only using 3-axis magnetometer, makes it efficient and possible to get the attitude and orbit information, without high-priced and complicated sensors. This method comprises 2 parts-one is the attitude determination and the other is the orbit determination by the magnetometer. In the attitude determination, 2-stage filter (Linear Kalman filter and Unscented Kalman filter) is applied and in the orbit determination, the Extended Kalman filter. The attitude determination accuracy is below 1°, the attitude angular rate determination accuracy below 0.005°/s and the orbital position determination accuracy below 10 kms when the measurement error of magnetometer is about 200nT. Thus, this study contributes to the mission of the micro satellites.
Ultrafast dynamics observation during femtosecond laser-material interaction
Authors: Guo Baoshan , Sun Jingya , Lu YongFeng , Jiang Lan 
Published: August 2019

Abstract
Femtosecond laser technology has attracted significant attention from the viewpoints of fundamental and application; especially femtosecond laser processing materials present the unique mechanism of laser-material interaction. Under the extreme nonequilibrium conditions imposed by femtosecond laser irradiation, many fundamental questions concerning the physical origin of the material removal process remain unanswered. In this review, cutting-edge ultrafast dynamic observation techniques for investigating the fundamental questions, including time-resolved pump-probe shadowgraphy, ultrafast continuous optical imaging, and four-dimensional ultrafast scanning electron microscopy, are comprehensively surveyed. Each technique is described in depth, beginning with its basic principle, followed by a description of its representative applications in laser-material interaction and its strengths and limitations. The consideration of temporal and spatial resolutions and panoramic measurement at different scales are two major challenges. Hence, the prospects for technical advancement in this field are discussed finally.
Acute Effect of Eating Sweets on Alcohol Cravings in a Sample with At-Risk Drinking
Authors: Cummings Jenna R , Ray Lara A , Nooteboom Peter , Tomiyama A Janet 
Published: August 2019

Abstract

Background
Alcohol craving, or the desire to drink alcohol, has been identified as a key experience preceding alcohol use. Alcoholics Anonymous has long claimed that individuals can allay alcohol cravings by eating sweets. Empirical tests of this strategy are limited to a few preclinical studies in rats, and there is no existing experiment testing the acute effect of eating sweets on alcohol cravings in humans.

Purpose
The current study sought to experimentally test the acute effect of eating sweets on alcohol cravings in a sample with at-risk drinking.

Methods
After being exposed to an alcohol cue, individuals with at-risk drinking (N = 150) were randomly assigned to eat sweets (n = 60), eat calorie-equivalent bland food (n = 60), or watch a video (n = 30). Caloric amounts were manipulated. Individuals with at-risk drinking were then exposed to a second alcohol cue. Changes in alcohol cravings from after the first to after the second alcohol cue were measured via visual analog scale and heart rate.

Results
There were no significant between-group differences in changes in alcohol cravings. Caloric amounts did not modify effects.

Conclusions
Experimental findings did not provide evidence to support the clinical lore that eating sweets can reduce alcohol cravings, albeit only acutely and for those with at-risk drinking. Other empirically supported strategies for managing alcohol cravings (e.g., pharmacotherapies, mindfulness) could instead be promoted.
Trail Making Test, Stroop, and Verbal Fluency: Regression-Based Norms for the Icelandic Population
Authors: Magnusdottir B B , Haraldsson H M , Sigurdsson E 
Published: August 2019

Abstract

Objective
The aim of this study was to construct regression-based norms for 3 executive-function tests: the Trail Making Test, Stroop, and Verbal Fluency.

Method
A sample of 1,034 healthy Icelandic adults (18–64 years) was used to calculate predicted scores for test measures from all 3 tests, controlled for the effects of age, gender, and education, as well as the interaction between these variables.

Results
The 3 demographic variables showed significant effects on most test measures and were included in the final equation for estimating predicted scores. An older age and less education predicted worse cognitive performances in most cases, and women tended to outperform men.

Conclusion
These results highlight the importance of adjusting for age, gender, and educational level when constructing normative data. Controlling for age alone may be insufficient or misleading in clinical-practice settings. A simple, user-friendly program for predicting executive-function test scores is provided.
A benchmarking of pipelines for detecting ncRNAs from RNA-Seq data
Authors: Di Bella Sebastiano , La Ferlita Alessandro , Carapezza Giovanni , Alaimo Salvatore , Isacchi Antonella , Ferro Alfredo , Pulvirenti Alfredo , Bosotti Roberta 
Published: August 2019

Abstract
Next-Generation Sequencing (NGS) is a high-throughput technology widely applied to genome sequencing and transcriptome profiling. RNA-Seq uses NGS to reveal RNA identities and quantities in a given sample. However, it produces a huge amount of raw data that need to be preprocessed with fast and effective computational methods. RNA-Seq can look at different populations of RNAs, including ncRNAs. Indeed, in the last few years, several ncRNAs pipelines have been developed for ncRNAs analysis from RNA-Seq experiments. In this paper, we analyze eight recent pipelines (iSmaRT, iSRAP, miARma-Seq, Oasis 2, SPORTS1.0, sRNAnalyzer, sRNApipe, sRNA workbench) which allows the analysis not only of single specific classes of ncRNAs but also of more than one ncRNA classes. Our systematic performance evaluation aims at guiding users to select the appropriate pipeline for processing each ncRNA class, focusing on three key points: (i) accuracy in ncRNAs identification, (ii) accuracy in read count estimation and (iii) deployment and ease of use.
Endothermy, offspring size and evolution of parental provisioning in vertebrates
Authors: Meiri Shai 
Published: August 2019

AbstractMammals and birds provide food for their young after birth, but such provisioning is almost absent in other vertebrates. A recent theory suggested that, in addition to thermoregulation, the large discrepancy in size between adult and young ectothermic vertebrates precludes them from providing for their young, whereas the relatively large offspring of endotherms are easier to provision. I show here that reptile neonates and hatchlings are as large as those of mammals and birds. Differences in size between adults and young thus cannot explain the lack of parental provisioning in reptiles. I suggest that the large size at birth is the ancestral condition in amniotes as a whole and that provisioning has thus evolved after endothermy.
Speciation of North American pygmy shrews (Eulipotyphla: Soricidae) supports spatial but not temporal congruence of diversification among boreal species
Authors: Hope Andrew G , Stephens Ryan B , Mueller Sarah D , Tkach Vasyl V , Demboski John R 
Published: August 2019

AbstractSpeciation among many animals was rapid through the Pleistocene, impacted by climate and periodic isolation and reconnection. As such, species limits among often morphologically cryptic lineages may remain unresolved despite clear mitogenomic partitioning. Accumulating evidence from phylogeographical studies is revealing congruent regional differentiation of lineages across taxonomic groups that share ecological and evolutionary traits. Here, we analyse multiple DNA loci and morphology to resolve the geography and timeframe associated with evolutionary history of North American pygmy shrews (genus Sorex). We then assess lineage diversification among three co-distributed shrew complexes using phylogenetic and approximate Bayesian computation approaches to test a hypothesis of spatial congruence but temporal incongruence of species formation on a continental scale. Our results indicate consistency in regional lineage distributions, partial congruence of the sequence of divergence, and strong but not definitive support for temporal incongruence, suggesting that successive glacial cycles initiated the process of diversification repeatedly through the Pleistocene. Our results emphasize a continuing need for greater genomic coverage in comparative phylogeography, with persistent challenges. We recognize distinct eastern (Sorex hoyi Baird, 1857) and western (Sorex eximius Osgood, 1901) species of pygmy shrew based on available evidence, but discuss issues with taxonomic designations considering the continuum of speciation throughout the boreal biome.
On causal discovery with an equal-variance assumption
Authors: Chen Wenyu , Drton Mathias , Wang Y Samuel 
Published: August 2019

Summary
Prior work has shown that causal structure can be uniquely identified from observational data when these follow a structural equation model whose error terms have equal variance. We show that this fact is implied by an ordering among conditional variances. We demonstrate that ordering estimates of these variances yields a simple yet state-of-the-art method for causal structure learning that is readily extendable to high-dimensional problems.
The endemic ‘sugar canes’ of Madagascar (Poaceae, Saccharinae: Lasiorhachis) are close relatives of sorghum
Authors: Vorontsova Maria S , Besnard Guillaume , Razanatsoa Jacqueline , Hackel Jan 
Published: August 2019

AbstractCrop wild relatives are important but often poorly known. This is the case for subtribe Saccharinae (Poaceae: Andropogoneae), which includes sugarcane (Saccharum) and sorghum (Sorghum). We present a phylogenetic and taxonomic account of the Malagasy endemic genus Lasiorhachis, previously included in Saccharum. New plastome and nuclear sequences were assembled from genome skimming data. Phylogenetic analyses of whole plastomes place Lasiorhachis as sister to Sorghum and only distantly related to the interbreeding Saccharum complex. This is also supported by analyses of nuclear ITS and partial assemblies for eight low-copy regions. Some nuclear regions suggest that Lasiorhachis is closer to Sorghum section Sorghum than other Sorghum spp. sometimes segregated as Vacoparis. We present a full taxonomic treatment of Lasiorhachis with an identification key, synonymy, typification, descriptions, drawings and a distribution map of the three species, all endemic to the central highlands of Madagascar. Lasiorhachis species occupy contrasting ecological niches and at least one of them, L. viguieri, has significance for ecosystem function. As crop wild relatives of sorghum, Lasiorhachis species should be included in germplasm collections.
Variable effects of a changing climate on lay dates and productivity across the range of the Red-cockaded Woodpecker
Authors: DeMay Stephanie M , Walters Jeffrey R 
Published: August 2019

AbstractMany temperate bird species are breeding earlier in response to warming temperatures. We examined the effects of climate on breeding phenology and productivity in 19 populations across the range of the Red-cockaded Woodpecker (Dryobates borealis), an endangered species endemic to pine (Pinus spp.) forests in the southeastern United States. Red-cockaded Woodpeckers nested earlier in warmer springs and delayed nesting in wetter springs. Earlier nesting and larger group sizes resulted in higher productivity. Spring temperatures have warmed over time across the range, but this has not led to range-wide advances in nesting date over time. Coastal and northern populations have exhibited a trend of earlier nesting over time, but the response of inland populations has been variable, including some populations in which nesting has become later over time. Geographic patterns included high and increasing productivity at higher latitudes, and declining productivity in the southwestern portion of the range, suggesting a possible shift in acceptable climate conditions for the species. Earlier nesting over time was associated with increasing productivity at higher latitudes, while elsewhere earlier nesting over time was associated with declining or stable productivity, suggesting that populations differ in their ability to adjust to a changing climate. The Red-cockaded Woodpecker is a habitat specialist heavily reliant on habitat management and has little capacity to shift its range, so its long-term viability will depend on its ability to adjust in place to changing local conditions.
Thermal physiology and activity in relation to reproductive status and sex in a free-ranging semelparous marsupial
Authors: Parker Cassandra A , Geiser Fritz , Stawski Clare 
Published: August 2019

Abstract
In a changing climate, southern hemisphere mammals are predicted to face rising temperatures and aridity, resulting in food and water shortages, which may further challenge already constrained energetic demands. Especially semelparous mammals may be threatened because survival of the entire population depends on the success of a single breeding event. One of these species, the yellow-footed antechinus, Antechinus flavipes, a small, heterothermic marsupial mammal, commences reproduction during winter, when insect prey is limited and energetic constraints are high. We examined the inter-relations between thermal and foraging biology of free-ranging A. flavipes and examined whether they use torpor for energy conservation, despite the fact that reproduction and torpor are considered to be incompatible for many mammals. Females used torpor during the reproductive season, but patterns changed with reproductive status. Prior to breeding, females used frequent (86% of days), deep and long torpor that was more pronounced than any other reproductive group, including pre-mating males (64% of days). Pregnant females continued to use torpor, albeit torpor was less frequent (28% of days) and significantly shorter and shallower than before breeding. Parturient and lactating females did not express torpor. During the mating period, males reduced torpor use (24% of days). Pre-reproductive females and pre-mating males were the least active and may use torpor to minimize predator exposure and enhance fat deposition in anticipation of the energetic demands associated with impending mating, gestation and lactation. Reproductive females were most active and likely foraged and fed to promote growth and development of young. Our data show that A. flavipes are balancing energetic demands during the reproductive season by modifying torpor and activity patterns. As the timing of reproduction is fixed for this genus, it is probable that climate change will render these behavioural and physiological adaptations as inadequate and threaten this and other semelparous species.