Flight results from the gravity-gradient-controlled RAE-1 satellite

1986 ◽  
Author(s):  
D. BLANCHARD
Keyword(s):  
Gravity Gradient

Progressive Early Rehabilitation Program Applied to Patients with Acute Cerebrovascular Accident

2020 ◽  
Vol 25 (3) ◽  
pp. 17-25 ◽  
Author(s):  
G. R. Ramazanov ◽  
L. B. Zavaliy ◽  
L. L. Semenov ◽  
S. A. Abudeev ◽  
A. O. Ptitsyn ◽  
...  
Keyword(s):  
Cerebrovascular Accident ◽  
Lung Ventilation ◽  
Rehabilitation Program ◽  
Artificial Lung ◽  
Early Rehabilitation ◽  
Gravity Gradient ◽  
Acute Cerebrovascular Accident ◽  
Artificial Lung Ventilation ◽  
Bed Days ◽  
Severity Of The Disease

Abstract. Early rehabilitation (ER) of patients with acute cerebrovascular accident (ACA) is one of the priority tasks of the vascular centers; the issue of increasing the volume of rehabilitation measures in the resuscitation and intensive care units (ICU) is relevant. Objective. To evaluate the safety and effectiveness of the progressive ER program in patients with ACA. Material and research methods. The study included 129 patients with ACA in ICU. Each patient of the main group (MGr, n = 61) underwent progressive ER: at least 4–5 vertical adjustments per day, passive mode Kinesiotherapy 49 ± 9.3 minutes, a double load of physiotherapy exercises, preventive physiotherapy; the total time of classes reached 240 minutes per day. In the comparison group (СGr, n = 68), standard ER was performed no more than 120 minutes per day. The groups are comparable by sex, age, severity of the disease and comorbidity. The severity of ACA, the gravity gradient, patient mobility, functional status, degree of dependence, and the presence of complications were evaluated. Results. During a month of work with the MGr, 102 ICU bed-days, 94 days of the artificial lung ventilation use, p < 0.05 were saved. Mortality in MGr decreased -— 8 patients (13.1%) versus 14 (20.6%) in CGr (p < 0.05). In patients within CGr, pulmonary thromboembolism developed in 8.8%, in MGr – in 3.3%. The severity of the apoplectic attack decreased ( by 28% in MGr, and by 20% in CGr ), mobility increased. Comparing the modalities of post resuscitationsyndrome in MGr, it was noted that the score decreased by 2 times from 6 [5; 6] to 3 [2.3; 3.3], but it has not changed in the CGr. Patients in the MGr were 2-–3 days earlier adapted to the vertical adjustment. Conclusions. The progressive ER program in ICU is safe, effective, realisable, and allows reducing the number of bed-days in ICU, the number of days of the artificial lung ventilation use, complications, and mortality in comparison with standard medical care.

scholarly journals The surface layer integral method for the modelling of the radial gravity gradient component over sea surface

2019 ◽  
Vol 9 (1) ◽  
pp. 127-132
Author(s):  
D. Zhao ◽  
Z. Gong ◽  
J. Feng
Keyword(s):  
Surface Layer ◽  
Integral Method ◽  
Integral Formula ◽  
Radial Component ◽  
Second Order ◽  
Sea Surface ◽  
Gravity Potential ◽  
Gravity Gradient ◽  
Disturbing Potential ◽  
Gradient Component

Abstract For the modelling and determination of the Earth’s external gravity potential as well as its second-order radial derivatives in the space near sea surface, the surface layer integral method was discussed in the paper. The reasons for the applicability of the method over sea surface were discussed. From the original integral formula of disturbing potential based on the surface layer method, the expression of the radial component of the gravity gradient tensor was derived. Furthermore, an identity relation was introduced to modify the formula in order to reduce the singularity problem. Numerical experiments carried out over the marine area of China show that, the modi-fied surface layer integral method effectively improves the accuracy and reliability of the calculation of the second-order radial gradient component of the disturbing potential near sea surface.

scholarly journals INS/gravity gradient aided navigation based on gravitation field particle filter

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 709-718
Author(s):  
Fanming Liu ◽  
Fangming Li ◽  
Xin Jing
Keyword(s):  
Particle Filter ◽  
Inertial Navigation System ◽  
Attractive Force ◽  
Gravity Gradient ◽  
Experimental Conditions ◽  
Gravitation Field ◽  
Disk Model ◽  
Swarm Optimization ◽  
Repulsion Force ◽  
Position Estimate

Abstract Swarm intelligence method is an effective way to improve the particle degradation and sample depletion of the traditional particle filter. This paper proposes a particle filer based on the gravitation field algorithm (GF-PF), and the gravitation field algorithm is introduced into the resampling process to improve particle degradation and sample depletion. The gravitation field algorithm simulates the solar nebular disk model, and introduces the virtual central attractive force and virtual rotation repulsion force between particles. The particles are moves rapidly to the high-likelihood region under action of the virtual central attractive force. The virtual rotation repulsion force makes the particles keep a certain distance from each other. These operations improve estimation performance, avoid overlapping of particles and maintain the diversity of particles. The proposed method is applied into INS/gravity gradient aided navigation, by combining the sea experimental data of an inertial navigation system. Compared with the particle swarm optimization particle filter(PSO-PF) and artificial physics optimized particle filter (APO-PF), the GF-PF has higher position estimate accuracy and faster convergence speed with the same experimental conditions.

The study of gravity gradient effect on attitude of low earth orbit satellite

2013 ◽  
Author(s):  
Nor Hazadura Hamzah ◽  
Sazali Yaacob ◽  
Hariharan Muthusamy ◽  
Norhizam Hamzah ◽  
Najah Ghazali
Keyword(s):  
Low Earth Orbit ◽  
Gravity Gradient ◽  
Earth Orbit ◽  
Gradient Effect ◽  
Orbit Satellite ◽  
Low Earth Orbit Satellite

scholarly journals Roto-Translational Control of Spacecraft in Low Earth Orbit Using Environmental Forces and Torques

2021 ◽  
Vol 11 (10) ◽  
pp. 4606
Author(s):  
Camilo Riano-Rios ◽  
Alberto Fedele ◽  
Riccardo Bevilacqua
Keyword(s):  
Translational Control ◽  
Attitude Control ◽  
Center Of Mass ◽  
Low Earth Orbit ◽  
Gravity Gradient ◽  
Adaptive Controllers ◽  
Attitude Error ◽  
Track Formation ◽  
Relative Orbit ◽  
Along Track

In this paper, relative orbit and attitude adaptive controllers are integrated to perform roto-translational maneuvers for CubeSats equipped with a Drag Maneuvering Device (DMD). The DMD enables the host CubeSat with modulation of aerodynamic forces/torques and gravity gradient torque. Adaptive controllers for independent orbital and attitude maneuvers are revisited to account for traslational-attitude coupling while compensating for uncertainty in parameters such as atmospheric density, drag/lift coefficients, location of the Center of Mass (CoM) and inertia matrix. Uniformly ultimately bounded convergence of the attitude error and relative orbit states is guaranteed by Lyapunov-based stability analysis for the integrated roto-translational maneuver. A simulation example of an along-track formation maneuver between two CubeSats with simultaneous attitude control using only environmental forces and torques is presented to validate the controller.

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