SATELLITE SELECTION ALGORITHMS FOR POSITIONING, NAVIGATION AND TIMING USERS

2022 ◽  
pp. 43-55
Author(s):  
В.О. Жилинский ◽  
Л.Г. Гагарина
Keyword(s):  
Spatial Location ◽  
Proper Solution ◽  
Navigation Problem ◽  
Advantages And Disadvantages ◽  
Satellite Constellation ◽  
Satellite Selection ◽  
Radio Signals ◽  
Geometric Dilution Of Precision ◽  
Selection Algorithms ◽  
The Relationship

Проведен обзор методов и алгоритмов формирования рабочего созвездия навигационных космических аппаратов при решении задач определения местоположения потребителя ГНСС. Появление новых орбитальных группировок и развитие прошлых поколений глобальных навигационных спутниковых систем (ГНСС) способствует увеличению как количества навигационных аппаратов, так и навигационных радиосигналов, излучаемых каждым спутником, в связи с чем решение проблемы выбора навигационных аппаратов является важной составляющей навигационной задачи. Рассмотрены исследования, посвященные типовым алгоритмам формирования рабочего созвездия, а также современным алгоритмам, построенным с привлечением элементов теории машинного обучения. Представлена связь ошибок определения координат потребителя, погрешностей определения псевдодальностей и пространственного расположения навигационных аппаратов и потребителя. Среди рассмотренных алгоритмов выделены три направления исследований: 1) нацеленных на поиск оптимального рабочего созвездия, обеспечивающего минимальную оценку выбранного геометрического фактора снижения точности; 2) нацеленных на поиск квазиоптимальных рабочих созвездий с целью уменьшения вычислительной сложности алгоритма ввиду большого количества видимых спутников; 3) позволяющих одновременно работать в совмещенном режиме по нескольким ГНСС. Приводятся особенности реализаций алгоритмов, их преимущества и недостатки. В заключении приведены рекомендации по изменению подхода к оценке эффективности алгоритмов, а также делается вывод о необходимости учета как геометрического расположения космических аппаратов, так и погрешности определения псевдодальности при выборе космического аппарата в рабочее созвездие The article provides an overview of methods and algorithms for forming a satellite constellation as a part of the navigation problem for the positioning, navigation and timing service. The emergence of new orbital constellations and the development of past GNSS generations increase both the number of navigation satellites and radio signals emitted by every satellite, and therefore the proper solution of satellite selection problem is an important component of the positioning, navigation and timing service. We considered the works devoted to typical algorithms of working constellation formation, as well as to modern algorithms built with the use of machine-learning theory elements. We present the relationship between user coordinates errors, pseudorange errors and the influence of spatial location of satellites and the user. Three directions of researche among reviewed algorithms are outlined: 1) finding the best satellite constellation that provides the minimum geometric dilution of precision; 2) finding quasi-optimal satellite constellation in order to reduce the computational complexity of the algorithm due to the large number of visible satellites; 3) possibility to work in a combined mode using radio signals of multiple GNSS simultaneously. The article presents the features of the algorithms' implementations, their advantages and disadvantages. The conclusion presents the recommendations to change the approach to assessing the performance of the algorithms, and concludes that it is necessary to take into account both the satellite geometric configuration, and pseudorange errors when satellite constellation is being formed

Fast satellite selection algorithm for GNSS multisystems based on the Sherman-Morrison formula

2021 ◽  
Author(s):  
Junpeng SHI ◽  
Kezhao LI ◽  
Lin CHAI ◽  
Lingfeng LIANG ◽  
Chengdong TIAN ◽  
...  
Keyword(s):  
Optimal Estimation ◽  
Observation Data ◽  
Selection Algorithm ◽  
Maximum Volume ◽  
Adaptive Function ◽  
Satellite Selection ◽  
Geometric Dilution Of Precision ◽  
Value Decomposition ◽  
Selection Algorithms ◽  
Usage Efficiency

Abstract The usage efficiency of GNSS multisystem observation data can be greatly improved by applying rational satellite selection algorithms. Such algorithms can also improve the real-time reliability and accuracy of navigation. By combining the Sherman-Morrison formula and singular value decomposition (SVD), a smaller geometric dilution of precision (GDOP) value method with increasing number of visible satellites is proposed. Moreover, by combining this smaller GDOP value method with the maximum volume of tetrahedron method, a new rapid satellite selection algorithm based on the Sherman-Morrison formula for GNSS multisystems is proposed. The basic idea of the algorithm is as follows: first, the maximum volume of tetrahedron method is used to obtain four initial reference satellites; then, the visible satellites are co-selected by using the smaller GDOP value method to reduce the GDOP value and improve the accuracy of the overall algorithm. By setting a reasonable precise threshold, the satellite selection algorithm can be autonomously run without intervention. The experimental results based on measured data indicate that (1) the GDOP values in most epochs over the whole period obtained with the satellite selection algorithm based on the Sherman-Morrison formula are less than 2. Furthermore, compared with the optimal estimation results of the GDOP for all visible satellites, the results of this algorithm can meet the requirements of high-precision navigation and positioning when the corresponding number of selected satellites reaches 13. Moreover, as the number of selected satellites continues to increase, the calculation time increases, but the decrease in the GDOP value is not obvious. (2) The algorithm includes an adaptive function based on the end indicator of the satellite selection calculation and the reasonable threshold. When the reasonable precise threshold is set to 0.01, the selected number of satellites in most epochs is less than 13. Furthermore, when the number of selected satellites reaches 13, the GDOP value is less than 2, and the corresponding probability is 93.54%. These findings verify that the proposed satellite selection algorithm based on the Sherman-Morrison formula provides autonomous functionality and high-accuracy results.

scholarly journals Theoretical and Methodological Approaches to Ecological Changes, Social Behaviour and Human Intergroup Tolerance 300,000 to 30,000 BP

2021 ◽  
Vol 28 (1) ◽  
pp. 53-75 ◽  
Author(s):  
Penny Spikins ◽  
Jennifer C. French ◽  
Seren John-Wood ◽  
Calvin Dytham
Keyword(s):  
Social Behaviour ◽  
Environmental Variability ◽  
Raw Materials ◽  
Modern Human ◽  
Resource Exploitation ◽  
Agent Based ◽  
Advantages And Disadvantages ◽  
Ecological Changes ◽  
The Relationship ◽  
Social Behaviours

AbstractArchaeological evidence suggests that important shifts were taking place in the character of human social behaviours 300,000 to 30,000 years ago. New artefact types appear and are disseminated with greater frequency. Transfers of both raw materials and finished artefacts take place over increasing distances, implying larger scales of regional mobility and more frequent and friendlier interactions between different communities. Whilst these changes occur during a period of increasing environmental variability, the relationship between ecological changes and transformations in social behaviours is elusive. Here, we explore a possible theoretical approach and methodology for understanding how ecological contexts can influence selection pressures acting on intergroup social behaviours. We focus on the relative advantages and disadvantages of intergroup tolerance in different ecological contexts using agent-based modelling (ABM). We assess the relative costs and benefits of different ‘tolerance’ levels in between-group interactions on survival and resource exploitation in different environments. The results enable us to infer a potential relationship between ecological changes and proposed changes in between-group behavioural dynamics. We conclude that increasingly harsh environments may have driven changes in hormonal and emotional responses in humans leading to increasing intergroup tolerance, i.e. transformations in social behaviour associated with ‘self-domestication’. We argue that changes in intergroup tolerance is a more parsimonious explanation for the emergence of what has been seen as ‘modern human behaviour’ than changes in hard aspects of cognition or other factors such as cognitive adaptability or population size.

Material Properties and Design Aspects of Folding Bicycle Frame

2011 ◽  
Vol 264-265 ◽  
pp. 777-782 ◽  
Author(s):  
M.A. Maleque ◽  
M.S. Hossain ◽  
S. Dyuti
Keyword(s):  
Material Properties ◽  
Raw Material ◽  
New Materials ◽  
Materials Properties ◽  
Advantages And Disadvantages ◽  
Bicycle Frame ◽  
Successful Design ◽  
Future Direction ◽  
The Relationship ◽  
Comprehensive Study

successful design of folding bicycle should take into account the function, material properties, and fabrication process. There are some other factors that should be considered in anticipating the behavior of materials for folding bicycle. In order to understand the relationship between material properties and design of a folding bicycle and also for the future direction in new materials with new design, a comprehensive study on the design under different conditions are essential. Therefore, a systematic study on the relationship between material properties and design for folding bicycle has been performed. The advantages and disadvantages matrix between conventional bicycle and folding bicycle is presented for better understanding of the materials properties and design. It was found that the materials properties of the folding bicycle frame such as fatigue and tensile strength are the important properties for the better performance of the frame. The relationship between materials properties and design is not straight forward because the behavior of the material in the finished product could be different from that of the raw material. The swing hinge technique could be a better technique in the design for the folding bicycle frame.

ON INTERACTION OF MATERIAL AND PROCEDURAL LAW IN THE CONTEXT OF REFORMING THE NOMENCLATURE OF SCIENTIFIC SPECIALTIES IN JURISPRUDENCE

2021 ◽  
Vol 3 (3) ◽  
pp. 214-231
Author(s):  
S.I. Suslova
Keyword(s):  
Civil Law ◽  
Scientific Research ◽  
Civil Procedure ◽  
Dialectical Logic ◽  
Advantages And Disadvantages ◽  
Procedural Law ◽  
Depth Study ◽  
Civil Science ◽  
Substantive Law ◽  
The Relationship

Introduction: the influence of the material branches of law on the content and development of procedural branches has long been substantiated in the legal literature. At the same time, civil law scholars, limited by the scope of the nomenclature of scientific specialties in legal sciences, do not have the opportunity to conduct dissertation research aimed at identifying the influence of procedural branches on the norms of substantive law. With regard to scientific research, the study of such an impact is currently permissible only within the specialty 12.00.15. Reforming the nomenclature of scientific specialties towards its enlargement creates the basis for the development of the scientific theory of intersectoral relations, developed by M.Iu. Chelyshev. An in-depth study of the intersectoral interaction of civil law and civil procedure will contribute not only to the development of scientific knowledge, but also will allow solving practical problems at a different methodological level. Purpose: to analyze the stages of the formation of scientific specialties in the context of the relationship between civil law and procedure, to identify the advantages and disadvantages of uniting and dividing civil law and procedure in scientific research, to analyze dissertations in different periods of development of the science of civil law and the science of civil procedure, to formulate ways to improve directions of research to bridge the gap between the science of civil law and procedure. Methods: empirical methods of description, interpretation; theoretical methods of formal and dialectical logic. The legal-dogmatic private scientific method was used. Results: identified the main views on the ratio of material and procedural branches in legal science; it is illustrated that the intersectoral approach is currently admissible only for dissertations in the specialty 12.00.15, which led to an almost complete absence of scientific research on this topic in civil science; substantiated the need to establish the bilateral nature of the relationship and interaction of material and procedural block. Conclusions: reforming the nomenclature of scientific specialties by right in the direction of their enlargement should have a positive effect on bridging the gap that has developed between works on civil law and civil law procedure in the last years of their separate existence. This is especially true of civil science, which developed its own scientific theories in isolation from the possibilities of their implementation within the framework of procedural law. The methodological basis for solving these problems has already been formed – this is an intersectoral method, the application of which is justified and demonstrated in the works of M.Iu. Chelyshev.

scholarly journals The Method for Product Design Selection with Incomplete Linguistic Weight Information Based on Quality Function Deployment in a Fuzzy Environment

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Ming Li
Keyword(s):  
Product Design ◽  
Quality Function Deployment ◽  
Design Development ◽  
Quality Function ◽  
Advantages And Disadvantages ◽  
Fuzzy Environment ◽  
Design Requirements ◽  
Design Selection ◽  
The Given ◽  
The Relationship

The selection of a design for the given product is a critical problem in product design development. Focuses of the designers and customers on the design are not identical. In order to bridge the gap and provide a more relaxing way to select the design, a new method based on quality function deployment (QFD) is proposed. In such a method, customers are required to give their linguistic preferences on the design with respect to the customer requirements (CRs). In the rating of the weight of CRs, they are allowed to provide incomplete linguistic weight information and the objective optimization model is proposed to derive the exact linguistic weight information. Designers are required to rate the correlation between design requirements (DRs) and the relationship between the CRs and DRs to construct the house of quality. Opinions given by the customers are translated into the opinions with respect to the DRs based on the QFD. Afterwards, the priorities of the designs and design requirements are determined. The assessment results not only show the contribution of each design requirement to the customer satisfaction but also show the advantages and disadvantages of each design from the designers’ perspective clearly and directly. An example is provided to validate the applicability of the proposed method.

scholarly journals Application of Latitude Stripe Division in Satellite Constellation Coverage to Ground

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Maocai Wang ◽  
Xin Luo ◽  
Guangming Dai ◽  
Xiaoyu Chen
Keyword(s):  
Orbital Period ◽  
High Efficiency ◽  
Classical Method ◽  
Grid Point ◽  
Spherical Geometry ◽  
Optimized Design ◽  
Target Region ◽  
Satellite Constellation ◽  
Orbital Periods ◽  
The Relationship

Grid point technique is a classical method in computing satellite constellation coverage to the ground regions. Aiming at improving the low computational efficiency of the conventional method, a method using latitude stripe division is proposed, which has high efficiency, and we name it latitude stripe method. After dividing the target region into several latitude stripes, the coverage status of each latitude stripe is computed by means of the spherical geometry relationship in the first orbital period. The longitude coverage intervals in the remaining orbital periods are computed by sliding the coverage status in the first orbital period. Based on this method, the instantaneous and cumulative coverage in simulation time can be calculated more efficiently. As well, the relationship between the cumulative coverage and altitude can be computed fast by this method, which could be used in the optimized design of repeating sun-synchronous orbits. The comparison between the conventional grid point method and the latitude stripe method shows that the latitude stripe method has high efficiency and accuracy. Through various case studies, the optimization in repeating sun-synchronous orbits design is successfully represented.

Comparative analysis of the equipment for the formation of navigation radio signals of the GLONASS system and features of group navigation radio signals

2021 ◽  
Vol 8 ◽  
pp. 29-38
Author(s):  
D.A. Astakhov ◽  
R.V. Bakit’ko ◽  
A.A. Potrikeyeva ◽  
R.F. Salakhov
Keyword(s):  
Comparative Analysis ◽  
Clear Picture ◽  
Effective Power ◽  
Advantages And Disadvantages ◽  
Power Amplification ◽  
Group Navigation ◽  
Radio Signals ◽  
Navigation Signals

In this paper comparative analysis of methods for forming navigation radio signals of the GLONASS system at each stage is presented. This analysis gives a clear picture of the evolution of the methods for forming navigation radio signals, and provides insights into their advantages and disadvantages. Special attention is paid to group navigation signals of the GLONASS system, namely the effective power amplification of the group navigation radiosignal.

Tree-Building Algorithms and Philosophies

2021 ◽  
pp. 142-185
Author(s):  
Andrew V. Z. Brower ◽  
Randall T. Schuh
Keyword(s):  
Computer Software ◽  
Bayesian Techniques ◽  
Advantages And Disadvantages ◽  
Computational Capability ◽  
Intractable Problems ◽  
Character Weighting ◽  
Alternative Approaches ◽  
Tree Building ◽  
The Relationship ◽  
Parsimony Criterion

This chapter evaluates “quantitative cladistics” in detail, including the issues of fit, parsimony algorithms, and character weighting. Although systematists have long associated characters with taxa, the relationship between character data and “phylogeny” has not always been obvious. The ideas of Willi Hennig clarified this relationship, and the formalization of these concepts in a quantitative method, via the parsimony criterion, allowed for computer implementation of phylogenetic inference and the feasible solution of previously intractable problems. It is this computational capability that took the study of taxonomic relationships from an almost purely qualitative and speculative enterprise to one dominated by the use of computer software and “objective” methodologies. The chapter then discusses the use, advantages, and disadvantages of maximum likelihood and Bayesian techniques as alternative approaches to the application of parsimony.

Finance

2021 ◽  
pp. 305-350
Keyword(s):  
Interest Rates ◽  
Financial Management ◽  
Financial Analysis ◽  
Time Value Of Money ◽  
Advantages And Disadvantages ◽  
Time Value ◽  
Tools And Techniques ◽  
Relationship Of ◽  
The Relationship ◽  
Value Of Money

This chapter deals with the principles of finance as applied in the foodservice industry. It discusses the concept of revenue management, financial analysis and reporting, financial control, principles of budgeting, and forecasting. Specifically, it discusses finance in general and of the financial system and the meaning and application of financial management. It introduces the basics of the advantages and disadvantages of the different types of organizations. The important topics presented are the relationship of finance to other business disciplines, basic financial information in decision-making, understand financial statements, and financial ratios. It applies several analysis tools and techniques to learn about the time value of money, interest, and interest rates.

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