scholarly journals Optimization-based Attitude Determination in Geodetic Applications

2020 ◽  
Vol 10 (1) ◽  
pp. 270-275
Author(s):  
Alexander Pesterev ◽  
Ivan Matrosov ◽  
Yury Morozov
Keyword(s):  
Rigid Body ◽  
Minimization Problem ◽  
Field Experiments ◽  
Attitude Determination ◽  
Traditional Approach ◽  
The Body ◽  
New Approach ◽  
Satellite Antenna ◽  
Initial Attitude ◽  
Magnetic Disturbances

AbstractA new approach to determining the attitude of a rigid body is suggested, which does not rely on the use of magnetometers. In the framework of this approach, the problem of determining the attitude reduces to solving a minimization problem for a function of three variables (angles characterizing the initial attitude of the body). The proposed method can be employed in precise geodetic measurements carried out with the use of a geodetic pole with a satellite antenna and an IMU installed on its top when, for some reasons, the surveyor cannot position the pole vertically (e.g., near walls or buildings). The use of the traditional approach, which relies on a compass and accelerometers, in this case does not ensure the desired accuracy of the attitude determination due to magnetic disturbances (both external ones and those induced by the receiver) affecting badly compass readings. The discussion is illustrated by results of field experiments.

An Integrated GPS/INS Navigation System for Land Vehicle

2013 ◽  
Vol 336-338 ◽  
pp. 221-226 ◽  
Author(s):  
Hossam Hendy ◽  
Xiao Ting Rui ◽  
Mostafa Khalil
Keyword(s):  
Experimental Work ◽  
Navigation System ◽  
Attitude Determination ◽  
The Body ◽  
Simulation Data ◽  
Land Vehicle ◽  
High Data ◽  
Mission Success ◽  
Initial Attitude ◽  
Filter Approach

A precise guided system needs an efficient control depending on a precise navigation algorithm, with the ability of getting an accurate initial attitude determination to guarantee the mission success. A navigation system is presented in this paper based on integration between inertial measuring unit and Global Positioning System via Kalman filter approach to satisfy an acceptant accuracy. The two well known Euler and Quaternion attitude determination techniques are implemented to evaluate the body orientation during motion. The carried out system is validated using both simulation data and experimental work. The simulation data is obtained using a six-degree-of-freedom model for a 122mm artillery rocket to obtain all ballistic trajectory parameters during flight. The experimental work is done using a land vehicle taking into consideration the initial attitude determination problem. The results showed high accuracy improvements with high data rates 200 Hz for full state navigation information (position, velocity and attitude).

scholarly journals Attitude Determination Algorithms through Accelerometers, GNSS Sensors, and Gravity Vector Estimator

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Raúl de Celis ◽  
Luis Cadarso
Keyword(s):  
Reference Frame ◽  
Velocity Vector ◽  
Reference Frames ◽  
Attitude Determination ◽  
The Body ◽  
Gravity Vector ◽  
New Approach ◽  
Spacecraft Navigation ◽  
Body Reference ◽  
Ballistic Projectiles

Aircraft and spacecraft navigation precision is dependent on the measurement system for position and attitude determination. Rotation of an aircraft can be determined measuring two vectors in two different reference systems. Velocity vector can be determined in the inertial reference frame from a GNSS-based sensor and by integrating the acceleration measurements in the body reference frame. Estimating gravity vector in both reference frames, and combining with velocity vector, determines rotation of the body. A new approach for gravity vector estimations is presented and employed in an attitude determination algorithm. Nonlinear simulations demonstrate that using directly the positioning and velocity outputs of GNSS sensors and strap-down accelerometers, aircraft attitude determination is precise, especially in ballistic projectiles, to substitute precise attitude determination devices, usually expensive and forced to bear high solicitations as for instance G forces.

scholarly journals Optimal control in liver kinetics

1986 ◽  
Vol 27 (3) ◽  
pp. 361-369 ◽  
Author(s):  
A. M. Fink
Keyword(s):  
Optimal Control ◽  
Minimization Problem ◽  
Enzymatic Reaction ◽  
The Body ◽  
Minimum Problem ◽  
Density Functions ◽  
Intermediate Form

AbstractWe solve a minimization problem in liver kinetics posed by Bass, et al., in this journal, (1984), pages 538–562. The problem is to choose the density functions for the location of two enzymes, in order to minimize the concentration of an intermediate form of a substance at the outlet of the liver. This form may be toxic to the rest of the body, but the second enzyme renders it harmless. It seems natural that the second enzyme should be downstream from the first. However, we can show that the minimum problem is sometimes solved by an overlap of the supports of the two density functions. Even more surprising is that, for certain forms of the kinetic functions and high levels of transformation of the first enzymatic reaction, some of the first enzyme should be located downstream from all the second enzyme. This suggests that the first reaction should be relatively slow.

A New Pattern of Old Fabric: Taʻlīm-i fārisī and the Grammatical Description of the Persian Language in the Ottoman Empire

2021 ◽  
Vol 27 (41) ◽  
pp. 31-48
Author(s):  
Munir Drkić ◽  
Ahmed Zildžić
Keyword(s):  
Ottoman Empire ◽  
19Th Century ◽  
Paradigm Shift ◽  
Traditional Approach ◽  
New Approach ◽  
Persian Language ◽  
European Languages ◽  
Language Students ◽  
The 19Th Century

This paper aims to examine the work entitled Taʻlīm-i fārisī in the context of the Ottoman tradition of the grammatical study of the Persian language. Taʻlīm-i fārisī, most likely penned by Kemal-pasha, is a short yet exceedingly significant primer for Persian language students dated in the middle of the 19th century. After a brief overview of the Persian grammar studies in the Ottoman Empire, the authors present the work and its author and conduct an analysis of the content of Taʻlīm-i fārisī. In terms of its underlying methodology, this work stands halfway between two principal tendencies: one is the traditional approach to studying the Persian language in the Ottoman Empire; another is a new approach developed under the influence of grammatical description of European languages. This paradigm shift in the Persian language's grammatical description within the Ottoman Empire is readily observable in the primer under review.

THE METHOD FOR EVALUATING ADAPTIVE CHANGES IN HUMAN MICROCIRCULATORY-TISSUE SYSTEMS

2020 ◽  
Vol 4 (1) ◽  
pp. 88-99
Author(s):  
A.V. DUNAEV
Keyword(s):  
Middle Finger ◽  
Analysis Data ◽  
The Body ◽  
Tissue Oxygen Saturation ◽  
Doppler Flowmetry ◽  
New Approach ◽  
Adaptive Changes ◽  
Palmar Surface ◽  
Tissue Systems ◽  
The Right

The work is aimed at developing a new approach to assessing adaptive changes in microcirculatory tissue systems when various loads are exerted on the body (sports or physiological stresses), based on the analysis of oscillations in microcirculatory blood flow and tissue oxygen saturation, measured by laser Doppler flowmetry (LDF) and tissue reflectance oximetry (TRO). The study involved eight healthy volunteers aged 21–49 years. Measurements were taken on the palmar surface of the middle finger of the right hand and the medial surface of the lower part of the forearm. The rhythmic oscillations of LDF and TRO were studied using wavelet analysis. Data analysis revealed resonant and synchronized oscillations in the LDF and TRO signals in the myogenic range as an adaptive change as a result of a reaction to physical activity and psychoemotional stress.

The Global Motion of a Rigid Body Subject to Periodic Body-Fixed Torques

1995 ◽  
Author(s):  
X. Tong ◽  
B. Tabarrok
Keyword(s):  
Rigid Body ◽  
Equations Of Motion ◽  
Melnikov Method ◽  
The Body ◽  
Body Motion ◽  
Heteroclinic Orbits ◽  
Coordinate Frame ◽  
Global Motion ◽  
Stable And Unstable Manifolds ◽  
Body Subject

Abstract In this paper the global motion of a rigid body subject to small periodic torques, which has a fixed direction in the body-fixed coordinate frame, is investigated by means of Melnikov’s method. Deprit’s variables are introduced to transform the equations of motion into a form describing a slowly varying oscillator. Then the Melnikov method developed for the slowly varying oscillator is used to predict the transversal intersections of stable and unstable manifolds for the perturbed rigid body motion. It is shown that there exist transversal intersections of heteroclinic orbits for certain ranges of parameter values.

Does a rigid body limit maneuverability?

2000 ◽  
Vol 203 (22) ◽  
pp. 3391-3396 ◽  
Author(s):  
J.A. Walker
Keyword(s):  
Rigid Body ◽  
The Body ◽  
Alternative Measure ◽  
Pectoral Fin ◽  
Caudal Fin ◽  
Minimum Radius ◽  
Current Definition ◽  
Theoretical Minimum

Whether a rigid body limits maneuverability depends on how maneuverability is defined. By the current definition, the minimum radius of the turn, a rigid-bodied, spotted boxfish Ostracion meleagris approaches maximum maneuverability, i.e. it can spin around with minimum turning radii near zero. The radius of the minimum space required to turn is an alternative measure of maneuverability. By this definition, O. meleagris is not very maneuverable. The observed space required by O. meleagris to turn is slightly greater than its theoretical minimum but much greater than that of highly flexible fish. Agility, the rate of turning, is related to maneuverability. The median- and pectoral-fin-powered turns of O. meleagris are slow relative to the body- and caudal-fin-powered turns of more flexible fish.

scholarly journals Aggregator of Demand Response for Renewable Integration and Customer Engagement: Strengths, Weaknesses, Opportunities, and Threats

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2391 ◽  
Author(s):  
Kody Ponds ◽  
Ali Arefi ◽  
Ali Sayigh ◽  
Gerard Ledwich
Keyword(s):  
Demand Response ◽  
Electricity Market ◽  
Swot Analysis ◽  
Traditional Approach ◽  
Customer Engagement ◽  
Energy Integration ◽  
New Approach ◽  
Advantages And Disadvantages ◽  
Knowledge Based ◽  
Political Economic

The world is progressing towards a more advanced society where end-consumers have access to local renewable-based generation and advanced forms of information and technology. Hence, it is in a current state of transition between the traditional approach to power generation and distribution, where end-consumers of electricity have typically been inactive in their involvement with energy markets and a new approach that integrates their active participation. This new approach includes the use of distributed energy resources (DER) such as renewable-based generation and demand response (DR), which are being rapidly adopted by end-consumers where incentives are strong. This paper presents the role of the DR aggregator to effectively integrate DER technology as a new source of energy capacity into electricity networks using information communication technology and industry knowledge., Based on DR aggregators, this framework will efficiently facilitate renewable energy integration and customer engagement into the electricity market. To this aim, advantages and disadvantages of DR aggregators are discussed in this paper from political, economic, social, and technological (PEST) points of view. Based on this analysis, a strengths, weaknesses, opportunities, and threats (SWOT) analysis for a typical DR aggregator is presented.

MULTIBODY DYNAMIC MODELING AND FLUTTER ANALYSIS OF A FLEXIBLE SLENDER VEHICLE

2012 ◽  
Vol 12 (06) ◽  
pp. 1250049 ◽  
Author(s):  
A. RASTI ◽  
S. A. FAZELZADEH
Keyword(s):  
Differential Equations ◽  
Rigid Body ◽  
Dynamic Modeling ◽  
Equations Of Motion ◽  
The Body ◽  
Elastic Deformations ◽  
Strip Theory ◽  
Multibody Dynamic ◽  
Flutter Analysis ◽  
Rigid Body Motions

In this paper, multibody dynamic modeling and flutter analysis of a flexible slender vehicle are investigated. The method is a comprehensive procedure based on the hybrid equations of motion in terms of quasi-coordinates. The equations consist of ordinary differential equations for the rigid body motions of the vehicle and partial differential equations for the elastic deformations of the flexible components of the vehicle. These equations are naturally nonlinear, but to avoid high nonlinearity of equations the elastic displacements are assumed to be small so that the equations of motion can be linearized. For the aeroelastic analysis a perturbation approach is used, by which the problem is divided into a nonlinear flight dynamics problem for quasi-rigid flight vehicle and a linear extended aeroelasticity problem for the elastic deformations and perturbations in the rigid body motions. In this manner, the trim values that are obtained from the first problem are used as an input to the second problem. The body of the vehicle is modeled with a uniform free–free beam and the aeroelastic forces are derived from the strip theory. The effect of some crucial geometric and physical parameters and the acting forces on the flutter speed and frequency of the vehicle are investigated.

scholarly journals Can't tell the caterpillars from the trees: countershading enhances survival in a woodland

2008 ◽  
Vol 275 (1651) ◽  
pp. 2539-2545 ◽  
Author(s):  
Hannah M Rowland ◽  
Innes C Cuthill ◽  
Ian F Harvey ◽  
Michael P Speed ◽  
Graeme D Ruxton
Keyword(s):  
Visual Cues ◽  
Field Experiments ◽  
Three Dimensional ◽  
Shape From Shading ◽  
The Body ◽  
Colour Pattern ◽  
Free Living ◽  
Background Matching ◽  
Lepidopteran Larvae ◽  
Beech Tree

Perception of the body's outline and three-dimensional shape arises from visual cues such as shading, contour, perspective and texture. When a uniformly coloured prey animal is illuminated from above by sunlight, a shadow may be cast on the body, generating a brightness contrast between the dorsal and ventral surfaces. For animals such as caterpillars, which live among flat leaves, a difference in reflectance over the body surface may degrade the degree of background matching and provide cues to shape from shading. This may make otherwise cryptic prey more conspicuous to visually hunting predators. Cryptically coloured prey are expected to match their substrate in colour, pattern and texture (though disruptive patterning is an exception), but they may also abolish self-shadowing and therefore either reduce shape cues or maintain their degree of background matching through countershading: a gradation of pigment on the body of an animal so that the surface closest to illumination is darker. In this study, we report the results from a series of field experiments where artificial prey resembling lepidopteran larvae were presented on the upper surfaces of beech tree branches so that they could be viewed by free-living birds. We demonstrate that countershading is superior to uniform coloration in terms of reducing attack by free-living predators. This result persisted even when we fixed prey to the underside of branches, simulating the resting position of many tree-living caterpillars. Our experiments provide the first demonstration, in an ecologically valid visual context, that shadowing on bodies (such as lepidopteran larvae) provides cues that visually hunting predators use to detect potential prey species, and that countershading counterbalances shadowing to enhance cryptic protection.

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