Evasive Maneuvers in Space Debris Environment and Technological Parameters

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sub-Optimal Orbital Maneuvers for Artificial Satellites

The determination of a specific orbit and the procedure to calculate orbital maneuvers of artificial satellites are problems of extreme importance in the study of orbital mechanics. Therefore, the transferring problem of a spaceship from one orbit to another, and the attention due to this subject has in increased during the last years. Many applications can be found in several space activities, for example, to put a satellite in a geostationary orbit, to change the position of a spaceship, to maintain a specific satellite's orbit, in the design of an interplanetary mission, and others. The Brazilian Satellite SCD-1 (Data Collecting Satellite) will be used as example in this paper. It is the first satellite developed entirely in Brazil, and it remains in operation to this date. SCD-1 was designed, developed, built, and tested by Brazilian scientists, engineers, and technicians working at INPE (National Institute for Space Research, and in Brazilian Industries. During the lifetime, it might be necessary do some complementary maneuvers, being this one either an orbital transferring, or just to make periodical corrections. The purpose of transferring problem is to change the position, velocity and the satellite's mass to a new pre determined state. This transfer can be totally linked (in the case of "Rendezvous") or partially free (free time, free final velocity, etc). In the global case, the direction, the orientation and the magnitude of the thrust to be applied must be chosen, respecting the equipment's limit. In order to make this transferring, either sub-optimal or optimal maneuvers may be used. In the present study, only the sub-optimal will be shown. Hence, this method will simplify the direction of thrust application, to allow a fast calculation that may be used in real time, with a very fast processing. The thrust application direction to be applied will be assumed small and constant, and the purpose of this paper is to find the time interval that the thrust is applied. This paper is basically divided into three parts: during the first one the sub-optimal maneuver is explained and detailed, the second presents the Satellite SCD-1, and finally the last part shows the results using the sub-optimal maneuver applied to the Brazilian Satellite.

Influência do pré-aquecimento na adaptação marginal de dois materiais seladores de fóssulas e fissuras, analisada através de tomografia de coerência ótica

Among the non-invasive techniques employed in the prevention of caries highlights the sealing pits and fissures which is a conservative maneuver, in order to obliterate them to protect them from attack acid bacteria. Influenced by the studies of pre-heating composite resin, which has experienced great improvement in some of their physical properties, this study aimed to evaluate in vitro the superficial and internal marginal adaptation of different materials and sealants in pre-heating or not. A total of 40 extracted human third molars (n=10) that had their occlusal surfaces prepared to receive sealant. We tested two types of sealing materials: resin sealant (Fluoroshield) and low-viscosity resin (Permaflo), where 50% of previously received heated material and the other half received sealant material at room temperature. All samples were subjected to thermal cycling and pH, simulating a cariogenic oral environment, and later were analyzed appliance OCT (optical coherence tomography). The images obtained alterations were recorded and analyzed statistically. Change was considered as the emergence of bubbles, gaps and cracks in the sealant. Comparisons of the same material, assessing the fact that it is not sealed or preheated material, as well as comparisons between different materials subjected to the same temperature were carried out. The nonparametric Tukey test was used (p < 0,05). The results showed that there was statistically significant difference between both the materials analyzed, as between the situations in which the sealant material was submitted (preheated or not). On the issue of marginal adaptation and internal surface, seen through Optical coherence tomography, may suggest that there is a difference between the use of one type or another of the sealing material analyzed, with superiority attributed to resin Permaflo compared to sealant Fluroshield, telling is the same for the different techniques used

Variations in dynamic knee valgus and gluteus medius onset timing in non-athletic females related to hormonal changes during the menstrual cycle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Foraging behavior of tyrant flycatchers (Aves, Tyrannidae) in Brazil

Este trabalho apresenta dados acerca do comportamento de forrageamento e substratos usados para a captura de presas por 28 espécies de tiranídeos (Tyrannidae) no Brasil. Para seis espécies: Arundinicola leucocephala Linnaeus, 1764, Fluvicola nengeta Linnaeus, 1766, Machetornis rixosa Vieillot, 1819, Myiozetetes similis Spix, 1825, Pitangus sulphuratus Linnaeus, 1766 e Tyrannus melancholicus Vieillot, 1819 -, também são apresentados dados sobre a altura do poleiro usado para caça, tempo de procura por presas, distância e ângulo de ataque. Com raras exceções, manobras do tipo sally strike foram as mais freqüentes, enquanto folhas vivas e o ar foram os substratos mais comumente usados para capturar presas. Para as seis espécies acima citadas três grupos de altura de forrageamento puderam ser discernidos: F. nengeta e M. rixosa forrageiam no chão, A. leucocephala e P. sulphuratus ocupam um estrato médio e T. melancholicus e M. similis formam um terceiro grupo e geralmente atacam suas presas a partir de poleiros situados a 3 m ou mais do chão. Com exceção de P. sulphuratus, que apresentou o tempo de procura mais longo, as outras cinco espécies não diferiram nesse aspecto. Três grupos foram também discernidos em relação à distância de ataque: F. nengeta e M. rixosa atacam presas próximas (< 2 m) a eles, A. leucocephala, P. sulphuratus e M. similis formam um grupo de média distância (3-4 m) e T. melancholicus apresentou as mais longas distâncias de ataque (até 12 m). As aves diferiram em alguns aspectos do ângulo de ataque que, juntamente com diferenças sutis em outros aspectos do comportamento de forrageamento podem levar a diferenças importantes na seleção de presas.

A respiração frenolabial na doença pulmonar obstrutiva crônica: revisão da literatura

Esta revisão teve por objetivo destacar os principais achados publicados nos últimos dez anos sobre os efeitos da respiração frenolabial (RFL) em pacientes com doença pulmonar obstrutiva crônica (DPOC). A busca dos artigos foi realizada nas bases de dados Lilacs, IBECS, MEDLINE e SciELO, por meio dos seguintes descritores da área da saúde (DeCS): doença pulmonar obstrutiva crônica, reabilitação, respiração, hiperinsuflação e dispneia, e suas respectivas versões na língua inglesa (MeSH), além do termo pursed-lip breathing. Após a eliminação dos títulos repetidos, foram selecionados somente os estudos que abordavam a RFL como tema principal, resultando em 12 artigos científicos, 10 ensaios clínicos e 2 revisões bibliográficas. Segundo os achados, a RFL proporciona: alterações sobre a gasometria arterial, caracterizada pelo aumento da saturação e pressão parcial de oxigênio; padrão ventilatório, com diminuição da frequência respiratória e aumento de tempo expiratório e do volume corrente; mecânica ventilatória, por meio do recrutamento de musculatura abdominal expiratória e dos músculos da caixa torácica e acessórios da inspiração; diminuição no consumo de oxigênio; alterações na modulação autonômica cardíaca induzida pelo aumento da atividade parassimpática e, por fim, melhora na qualidade de vida destes pacientes. A RFL é considerada uma manobra de grande importância, por repercutir de forma positiva em diversos sistemas e sobre a qualidade de vida de pacientes portadores da DPOC.

Intubação traqueal e o paciente com o estômago cheio

A aspiração pulmonar do conteúdo gástrico, apesar de pouco frequente, exige cuidados especiais para sua prevenção. A depressão da consciência durante a anestesia predispõe os pacientes a esta grave complicação pela diminuição na função do esfíncter esofágico e dos reflexos protetores das vias aéreas. Guias de jejum pré-operatório elaborados recentemente sugerem períodos menores de jejum, principalmente para líquidos, permitindo mais conforto aos pacientes e menor risco de hipoglicemia e desidratação, sem aumentar a incidência de aspiração pulmonar perioperatória. O uso rotineiro de agentes que diminuem a acidez e volume gástrico parece estar indicado apenas para pacientes de risco. A intubação traqueal após indução anestésica por meio da técnica de sequência rápida está indicada naqueles pacientes, com risco de aspiração gástrica, em que não há suspeita de intubação traqueal difícil. A indicação correta da técnica, sua aplicação criteriosa e a utilização racional das drogas disponíveis podem promover condições excelentes de intubação, com curto período de latência, rápido retorno da consciência e da respiração espontânea, caso haja falha na intubação traqueal.O presente artigo tem como objetivo discutir os métodos atualmente utilizados para controlar o volume e o pH do conteúdo gástrico, proteger as vias aéreas durante as manobras de intubação e reduzir o refluxo gastroesofágico.

CHARACTERISTICS OF ARTERIAL-HYPERTENSION IN RESPONSE TO BOLUS INJECTION OF PHENYLEPHRINE IN ATROPINIZED PATIENTS

The changes of arterial pressure promoted by bolus injection of 50 mg phenylephrine (PHE) were studied in 20 atropinized patients (5 normal subjects, 13 patients with mitral valve disease, 1 patient with essential arterial hypertension and 1 patient with hypertrophic cardiomyopathy) submitted to routine catheterism. Patients with aortic valve disease, left ventricular outflow tract obstruction and intracardiac shunt were excluded from the study. All patients were in sinus rhythm, without heart failure. Arterial pressure started to increase at 14.8 +/- 5.4 s (range, 5.6 to 27 s; mean +/- SD) after PHE. There was an increase of 37.8 +/- 16.7 mmHg (range, 12.5 to 70 mmHg) in systolic pressure and of 26.6 +/- 11.1 mmHg (range, 7.5 to 42.5 mmHg) in diastolic pressure. Peak hypertension was attained at 36.6 +/- 16.4 s (range, 10.8 to 64.9 s) and hypertension continued for 176 +/- 92 s (range, 11 to 365 s). Heart rate was 114 +/- 21 bpm before PHE and 111 +/- 21 bpm (P<0.05) after PHE. There were no adverse events associated with intravenous PHE injection in any patient, in accordance with the general view that bolus injection of PHE is a safe and practical maneuver to promote arterial hypertension.

An analytical and numerical study of plane change maneuvers using aerodynamic force

The goal of the present work is to analyze space missions that use the terrestrial atmosphere to accomplish orbital maneuvers that involve a plane change. A set of analytical solutions is presented for the variation of the orbital elements due to a single passage through the atmosphere, assuming that the interval the spacecraft travels through the atmosphere is not too large. The study considers both the lift influence on the spacecraft orbit as well as drag. The final equations are tested with numerical integration and can be considered in accordance with the numerical results whenever the perigee height is larger than a critical value. Next, a numerical study of the ratio between the velocity increment required to correct the semimajor axis decay due to the atmospheric passage and the velocity variation required to obtain the change in the inclination is also presented. This analysis can be used to decide if a maneuver passing through the atmosphere can decrease the fuel consumption of the mission and, in the cases where this technique can be used, if a multiple passage is more efficient than a single passage.

Effects of the eccentricity on the primaries in the gravitational capture phenomenon

Gravitational capture is a characteristic of some dynamical systems in celestial mechanics, as in the elliptic restricted three-body problem that is considered in this paper. The basic idea is that a spacecraft (or any particle with negligible mass) can change a hyperbolic orbit with a small positive energy around a celestial body into an elliptic orbit with a small negative energy without the use of any propulsive system. The force responsible for this modification in the orbit of the spacecraft is the gravitational force of the third body involved in the dynamics. In this way, this force is used as a zero cost control, equivalent to a continuous thrust applied in the spacecraft. One of the most important applications of this property is the construction of trajectories to the Moon. The objective of the present paper is to study in some detail the effects of the eccentricity of the primaries in this maneuver.

Strategies for plane change of Earth orbits using lunar gravity and derived trajectories of family G

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Alternative Transfers to the NEOs 99942 Apophis, 1994 WR12, and 2007 UW1 via Derived Trajectories from Periodic Orbits of Family G

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of the eccentricity on the primames in the gravitational capture phenomenon

Gravitational capture is a characteristic of some dynamical systems in celestial mechanics, as in the elliptic restricted three-body problem that is considered in this paper. The basic idea is that a spacecraft (or any particle with negligible mass) can change a hyperbolic orbit with a small positive energy around a celestial body into an elliptic orbit with a small negative energy without the use of any propulsive system. The force responsible for this modification in the orbit of the spacecraft is the gravitational force of the third body involved in the dynamics. In this way, this force is used as a zero cost control, equivalent to a continuous thrust applied in the spacecraft. One of the most important applications of this property is the construction of trajectories to the Moon. The objective of the present paper is to study in some detail the effects of the eccentricity of the primaries in this maneuver.

Interplanetary natural routes via Moon and Lagrangiam points L1 and L2

Swing-by techniques are extensively used in interplanetary missions to minimize fuel consumption and to raise payloads of spaceships. The effectiveness of this type of maneuver has been proven since the beginning of space exploration. According to this premise, we have explored the existence of a natural and direct links between low Earth orbits and the lunar sphere of influence, to obtain low-energy interplanetary trajectories through swing-bys with the Moon and the Earth. The existence of these links are related to a family of retrograde periodic orbits around the Lagrangian equilibrium point L1 predicted for the circular, planar, restricted three-body Earth-Moon-particle problem. The trajectories in these links are sensitive to small disturbances. This enables them to be conveniently diverted reducing so the cost of the swing-by maneuver. These maneuvers allow us a gain in energy sufficient for the trajectories to escape from the Earth-Moon system and to stabilize in heliocentric orbits between the Earth and Venus or Earth and Mars. On the other hand, still within the Earth sphere of influence, and taking advantage of the sensitivity of the trajectories, is possible to design other swing-bys with the Earth or Moon. This allows the trajectories to have larger reach, until they can reach the orbit of other planets as Venus and Mars.(3σ)Broucke, R.A., Periodic Orbits in the Restricted Three-Body Problem with Earth-Moon Masses, JPL Technical Report 32-1168, 1968.

Price-based capital account regulations: the Colombian experience

Includes bibliography