scholarly journals Effects of Separation Strategy on Deployment of Multitethered Chain-Type Satellite System

2016 ◽  
Vol 2016 ◽  
pp. 1-15
Author(s):  
Jinxiu Zhang ◽  
Zhigang Zhang
Keyword(s):  
Dynamic Behavior ◽  
Satellite System ◽  
Synchronous Motion ◽  
System A ◽  
Separation Velocity ◽  
Spring Mechanism ◽  
Separation Strategy ◽  
Three Body ◽  
Newtonian Method ◽  
Chain Type

This paper investigates the effects of separation strategy and parameters related to deployment on the dynamic behavior of multitethered chain-type satellite system. The system, including several satellites connected by tethers which are considered as massless and straight, is modeled as an extension of a two-body dumbbell tethered system. The dynamic equations of system in absence of perturbations and external disturbances are derived using Newtonian Method. To observe the effect of deployment rate on the motion of system, a parametric analysis of the deployment of a three-body tethered system with different deployment rates is carried out. Moreover, a four-body tethered system is used to investigate the effect of separation strategies on the dynamic behavior of system during the deployment phase. The numerical results suggest that the system with simultaneous separation costs less time to complete the deployment. If the ratio of deployment rates is in consistence with that of their desired lengths, the tethers deployed simultaneously would have a synchronous motion. It is also observed that the system employing separation bolt has a better performance than the system separated by spring mechanism since the larger separation velocity which is not along local vertical may cause a rotation.

Catastrophe Analysis of Planar Three-Spring Systems

1998 ◽  
Author(s):  
J. P. Yin ◽  
D. Marsh ◽  
J. Duffy
Keyword(s):  
Contact Force ◽  
Force Control ◽  
Energy Function ◽  
System A ◽  
Spring System ◽  
Spring Mechanism ◽  
And Control ◽  
Control Tool ◽  
Contact Force Control

Abstract A special planar three-spring mechanism is proposed for contact force control. An energy function is defined to describe the behavior of this kind of mechanism. It can be used to perform the catastrophe analysis of this mechanism. The analysis result can be used as a design and control tool. By comparing the three-spring system and a two-spring system, we found the three-spring mechanism has better stability than the two-spring system. A three-spring mechanism which can be used to control a general contact force in a plane is also analyzed.

A Modal Transient Simulation Model for Flexible Asymmetric Rotors

1976 ◽  
Vol 98 (1) ◽  
pp. 312-319 ◽  
Author(s):  
D. W. Childs
Keyword(s):  
Simulation Model ◽  
Dynamic Behavior ◽  
Transient Simulation ◽  
Synchronous Motion ◽  
Stiffness Properties ◽  
Transient Simulations ◽  
Modal Coordinates ◽  
Physical Dimensions

A simulation model is developed which accounts for an orthotropic as opposed to an axisymmetric rotor, i.e., rotors are considered whose stiffness and inertial properties in two mutually orthogonal planes are different. A rotor-fixed formulation is employed to define the rotor’s elastic deflections. Favorable characteristics of this formulation are that (a) the rotor’s inertial and stiffness properties are constant, and (b) the modal coordinates are nonoscillatory during synchronous motion. The validity of the formulation is verified by conducting transient simulations for a rotor having the approximate physical dimensions of a two-pole 500 MW alternator. The simulation model correctly simulates the rotor’s theoretically predicted dynamic behavior.

scholarly journals Regular and Chaotic Motion in a Restricted Three–Body Problem of Astrophysical Interest

2000 ◽  
Vol 174 ◽  
pp. 281-285 ◽  
Author(s):  
J. C. Muzzio ◽  
F. C. Wachlin ◽  
D. D. Carpintero
Keyword(s):  
External Field ◽  
Body Problem ◽  
Stellar System ◽  
Three Dimensional ◽  
Restricted Three Body Problem ◽  
Three Body Problem ◽  
Stellar Orbits ◽  
System A ◽  
Regular And Chaotic Motion ◽  
Three Body

AbstractWe have studied the motion of massless particles (stars) bound to a stellar system (a galactic satellite) that moves on a circular orbit in an external field (a galaxy). A large percentage of the stellar orbits turned out to be chaotic, contrary to what happens in the usual restricted three–body problem of celestial mechanics where most of the orbits are regular. The discrepancy is probably due to three facts: 1) Our study is not limited to orbits on the main planes of symmetry, but considers three–dimensional motion; 2) The force exerted by the satellite goes to zero (rather than to infinity) at the center of the satellite; 3) The potential of the satellite is triaxial, rather than spherical.

Dynamic behavior and strategy for the complete 1H and 13C assignments for meso-aryl expanded heptaphyrins

2002 ◽  
Vol 06 (06) ◽  
pp. 410-422 ◽  
Author(s):  
Bhawani S. Joshi ◽  
Venkataramanarao G. Anand ◽  
Simi K. Pushpan ◽  
Alagar Srinivasan ◽  
Tavarekere K. Chandrashekar ◽  
...  
Keyword(s):  
Dynamic Behavior ◽  
Intramolecular Hydrogen Bonding ◽  
Native State ◽  
Temperature Dependent ◽  
System A ◽  
Expanded Porphyrins ◽  
Nmr Techniques ◽  
Intramolecular Hydrogen ◽  
C Nmr

The detailed 1 H and 13 C NMR analysis of 5,10,19,24-tetramesityl-33,35,36,38,39-pentathiaheptaphyrin (1) and 5,10,19,24-tetraphenyl-35,36-dioxa-33,38,39-trithiaheptaphyrin (2) in the native and protonated state were carried out using two-dimensional NMR techniques. The analysis suggests that the earlier reported structure containing inverted terminal thiophene of trithiophene should be corrected as the inverted thiophene and furan of bithiophene and bifuran instead of trithiophene system of 1 and 2, respectively. Temperature dependent and titration studies suggest that 1 is less flexible in the native state then 2 due to presence of the mesityl group despite having disorder due to the presence of the heavier sulphur atom. This was consequently proven by the NMR information obtained in 5,10,19,24-tetramesityl-35,36-dioxa-33,38,39-trithiaheptaphyrin (3). Whereas in its protonated state, 2 was found to be less flexible than 1 due to presence of intramolecular hydrogen bonding involving N - H --- O between the pyrrole NH and oxygen of the furan of bifuran system. A systematic NMR strategy has been generated in order to provide complete a structure determination of expanded porphyrins along with their dynamic behavior.

scholarly journals The Social Disruptiveness of Digital Agricultural Technologies: Asking Questions in the Context(s) that Matter

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Abdul-Rahim Abdulai
Keyword(s):  
Food System ◽  
Satellite System ◽  
Agricultural Technologies ◽  
Rural Landscapes ◽  
Incremental Change ◽  
System A ◽  
Rural Settings ◽  
The Social ◽  
Asking Questions ◽  
Agriculture And Food

Agriculture and food, the sector at the centre of many debates on technology driven human civilization, may be at the onset of another transformation: a transformation showing glimpse of both old and new revolutionary and incremental change in what farming means, where and how it is done and our relationship to the land, especially within rural settings. Today, food and agricultural systems are once again experiencing what can be described as another technological surge, a digital-driven potential transition. Emerging technologies including mobile support systems, precision agricultural tools, drone technologies, RFID and blockchain, sensors, satellite system, just to mention a few, are being employed across the food system, a system intrinsically and extrinsically connected to the what and the how of the countryside. There is no hiding that these recent development holds broader implications for both agriculture and farming, and rurality at large. However, at present, we are oblivious to the particularities of these implications. But we need to start the conversations about the implications for the rural to adequately prepare for what it has in stock for rural development and restructuring. What I seek to do in my research is to begin to ask some social questions on the digital surge in agriculture, with specific emphasis on how it will affect practices and performalities of rurality across rural landscapes. It is my intention to spur initial discussions with this preliminary presentation and engage audiences in exploring specific forms of the rural and farming that should be considered in this emerging field.

scholarly journals O Efeito das Covariâncias entre os Componentes de Linha Base sobre a Confiabilidade de Redes GNSS: Resultados para uma Rede com Alta Redundância

2021 ◽  
Vol 73 (2) ◽  
pp. 666-684
Author(s):  
Maria Luísa Silva Bonimani ◽  
Vinicius Francisco Rofatto ◽  
Marcelo Tomio Matsuoka ◽  
Ivandro Klein ◽  
Mauricio Roberto Veronez ◽  
...  
Keyword(s):  
Global Navigation Satellite System ◽  
Satellite System ◽  
Navigation Satellite ◽  
System A ◽  
Global Navigation ◽  
Global Navigation Satellite

A mais recente versão da teoria da confiabilidade tem sido utilizada para descrever a capacidade de um sistema de medição em detectar, identificar e remover outliers a um certo nível de probabilidade. Entretanto, as aplicações desta teoria têm sido direcionadas para redes simuladas de nivelamento. Aqui, por outro lado, aplicamos a teoria no contexto de redes baseadas nos sistemas de posicionamento por satélites GNSS (Global Navigation Satellite System), a partir de dados reais coletados em campo. Testamos se as covariâncias entre as componentes da linha base têm efeito sobre a confiabilidade. Verificamos que as covariâncias entre as componentes da linha base aumentam a taxa de sucesso na identificação de outlier e, portanto, aumentam a confiabilidade da rede. O menor outlier identificável – ao nível de 80% de correta identificação – teve uma redução média de ~30% para as componentes ΔX e ΔY, e ~14% para ΔZ em comparação ao cenário com covariâncias nulas. O aumento do nível de significância melhora a confiabilidade em ambos os cenários (covariâncias nulas e não-nulas) na mesma proporção. Porém, para altos níveis de significância (α > 0,1) e sistemas com boa redundância (ri > 0,5), a confiabilidade para um modelo estocástico com covariâncias nulas se aproxima do caso em que as covariâncias não são nulas. Na ausência de um modelo estocástico mais realista (covariâncias não-nulas) e para sistemas com boa redundância local (ri > 0,5), deve-optar por regiões críticas maiores ( k < 2,8).

scholarly journals Gargantuan chaotic gravitational three-body systems and their irreversibility to the Planck length

2020 ◽  
Vol 493 (3) ◽  
pp. 3932-3937 ◽  
Author(s):  
T C N Boekholt ◽  
S F Portegies Zwart ◽  
M Valtonen
Keyword(s):  
Dynamical Systems ◽  
Free Fall ◽  
Quantitative Relation ◽  
Double Precision ◽  
Planck Length ◽  
Rounding Errors ◽  
Massive Black Holes ◽  
System A ◽  
N Body Problem ◽  
Three Body

ABSTRACT Chaos is present in most stellar dynamical systems and manifests itself through the exponential growth of small perturbations. Exponential divergence drives time irreversibility and increases the entropy in the system. A numerical consequence is that integrations of the N-body problem unavoidably magnify truncation and rounding errors to macroscopic scales. Hitherto, a quantitative relation between chaos in stellar dynamical systems and the level of irreversibility remained undetermined. In this work, we study chaotic three-body systems in free fall initially using the accurate and precise N-body code Brutus, which goes beyond standard double-precision arithmetic. We demonstrate that the fraction of irreversible solutions decreases as a power law with numerical accuracy. This can be derived from the distribution of amplification factors of small initial perturbations. Applying this result to systems consisting of three massive black holes with zero total angular momentum, we conclude that up to 5 per cent of such triples would require an accuracy of smaller than the Planck length in order to produce a time-reversible solution, thus rendering them fundamentally unpredictable.

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