International Nuclear Information System (INIS)
Buchman, S; Lipa, J A; Keiser, G M; Muhlfelder, B; Turneaure, J P
2015-01-01
The Gravity Probe B (GP-B) gyroscope, a unique cryogenically operated mechanical sensor, was used on-orbit to independently test two predictions of general relativity (GR). Here, we describe the development and performance of the GP-B gyroscope, its geometry and fabrication, spin-up and vacuum approach, magnetic considerations, and static charge management. The history of electrically suspended gyroscopes puts the current work in context. Fabrication and ground testing of the GP-B gyroscope are detailed, followed by a review of on-orbit initialization, calibration, operation, and performance. We find that the performance was degraded relative to the mission goals, but was still sufficient to provide excellent new tests of GR. The degradation is partially due to the existence of gyroscope torques due to an unanticipated interaction between patch potentials on the rotor and the housing. We discuss these patch potentials and describe the effect of related torques on gyro drift. It was essential to include models for the effects due to the patch potentials in the complete data analysis model to yield determinations of the two GR effects. (paper)
Gravity Probe B Gyroscope Rotor
2003-01-01
The Gravity Probe B (GP-B) is the relativity experiment developed at Stanford University to test two extraordinary predictions of Albert Einstein's general theory of relativity. The experiment will measure, very precisely, the expected tiny changes in the direction of the spin axes of four gyroscopes contained in an Earth-orbiting satellite at a 400-mile altitude. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are very slightly warped by the presence of the Earth, and, more profoundly, how the Earth's rotation very slightly drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. This photograph is a close up of a niobium-coated gyroscope motor and its housing halves. GP-B is among the most thoroughly researched programs ever undertaken by NASA. This is the story of a scientific quest in which physicists and engineers have collaborated closely over many years. Inspired by their quest, they have invented a whole range of technologies that are already enlivening other branches of science and engineering. Launched April 20, 2004 , the GP-B program was managed for NASA by the Marshall Space Flight Center. Development of the GP-B is the responsibility of Stanford University along with major subcontractor Lockheed Martin Corporation. (Image credit to Don Harley.)
The Gravity-Probe-B relativity gyroscope experiment - Development of the prototype flight instrument
Turneaure, J. P.; Everitt, C. W. F.; Parkinson, B. W.; Bardas, D.; Breakwell, J. V.
1989-01-01
The Gravity-Probe-B relativity gyroscope experiment (GP-B) will measure the geodetic and frame-dragging precession rates of gyroscopes in a 650 km high polar orbit about the earth. The goal is to measure these two effects, which are predicted by Einstein's General Theory of Relativity, to 0.01 percent (geodetic) and 1 percent (frame-dragging). This paper presents the development progress for full-size prototype flight hardware including the gyroscopes, gyro readout and magnetic shielding system, and an integrated ground test instrument.
Investigation of a geodesy coexperiment to the Gravity Probe B relativity gyroscope program
Everitt, C. W. F.; Parkinson, Bradford W.; Tapley, Mark
1993-01-01
Geodesy is the science of measuring the gravitational field of and positions on the Earth. Estimation of the gravitational field via gravitation gradiometry, the measurement of variations in the direction and magnitude of gravitation with respect to position, is this dissertation's focus. Gravity Probe B (GP-B) is a Stanford satellite experiment in gravitational physics. GP-B will measure the precession the rotating Earth causes on the space time around it by observing the precessions of four gyroscopes in a circular, polar, drag-free orbit at 650 km altitude. The gyroscopes are nearly perfect niobium-coated spheres of quartz, operating at 1.8 K to permit observations with extremely low thermal noise. The permissible gyroscope drift rate is miniscule, so the torques on the gyros must be tiny. A drag-free control system, by canceling accelerations caused by nongravitational forces, minimizes the support forces and hence torques. The GP-B system offers two main possibilities for geodesy. One is as a drag-free satellite to be used in trajectory-based estimates of the Earth's gravity field. We described calculations involving that approach in our previous reports, including comparison of laser only, GPS only, and combined tracking and a preliminary estimate of the possibility of estimating relativistic effects on the orbit. The second possibility is gradiometry. This technique has received a more cursory examination in previous reports, so we concentrate on it here. We explore the feasibility of using the residual suspension forces centering the GP-B gyros as gradiometer signals for geodesy. The objective of this work is a statistical prediction of the formal uncertainty in an estimate of the Earth's gravitation field using data from GP-B. We perform an instrument analysis and apply two mathematical techniques to predict uncertainty. One is an analytical approach using a flat-Earth approximation to predict geopotential information quality as a function of spatial
Gravity Probe B: final results of a space experiment to test general relativity.
Everitt, C W F; DeBra, D B; Parkinson, B W; Turneaure, J P; Conklin, J W; Heifetz, M I; Keiser, G M; Silbergleit, A S; Holmes, T; Kolodziejczak, J; Al-Meshari, M; Mester, J C; Muhlfelder, B; Solomonik, V G; Stahl, K; Worden, P W; Bencze, W; Buchman, S; Clarke, B; Al-Jadaan, A; Al-Jibreen, H; Li, J; Lipa, J A; Lockhart, J M; Al-Suwaidan, B; Taber, M; Wang, S
2011-06-03
Gravity Probe B, launched 20 April 2004, is a space experiment testing two fundamental predictions of Einstein's theory of general relativity (GR), the geodetic and frame-dragging effects, by means of cryogenic gyroscopes in Earth orbit. Data collection started 28 August 2004 and ended 14 August 2005. Analysis of the data from all four gyroscopes results in a geodetic drift rate of -6601.8±18.3 mas/yr and a frame-dragging drift rate of -37.2±7.2 mas/yr, to be compared with the GR predictions of -6606.1 mas/yr and -39.2 mas/yr, respectively ("mas" is milliarcsecond; 1 mas=4.848×10(-9) rad).
Range, Shannon K'doah; Mullins, Jennifer
This teaching guide introduces a relativity gyroscope experiment aiming to test two unverified predictions of Albert Einstein's general theory of relativity. An introduction to the theory includes the following sections: (1) "Spacetime, Curved Spacetime, and Frame-Dragging"; (2) "'Seeing' Spacetime with Gyroscopes"; (3)…
2000-01-01
The space vehicle Gravity Probe B (GP-B) is the relativity experiment developed at Stanford University to test two extraordinary predictions of Albert Einstein's general theory of relativity. The experiment will measure, very precisely, the expected tiny changes in the direction of the spin axes of four gyroscopes contained in an Earth-orbiting satellite at a 400-mile altitude. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are very slightly warped by the presence of the Earth, and, more profoundly, how the Earth's rotation very slightly drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. GP-B is among the most thoroughly researched programs ever undertaken by NASA. This is the story of a scientific quest in which physicists and engineers have collaborated closely over many years. Inspired by their quest, they have invented a whole range of technologies that are already enlivening other branches of science and engineering. In this photograph, engineer Gary Reynolds is inspecting the inside of the probe neck during probe thermal repairs. GP-B is scheduled for launch in April 2004 and managed for NASA by the Marshall Space Flight Center. Development of the GP-B is the responsibility of Stanford University along with major subcontractor Lockheed Martin Corporation. (Image credit to Russ Leese, Gravity Probe B, Stanford University)
2004-01-01
In this photo, the Gravity Probe B (GP-B) space vehicle is being encapsulated atop the Delta II launch vehicle. The GP-B is the relativity experiment developed at Stanford University to test two extraordinary predictions of Albert Einstein's general theory of relativity. The experiment will measure, very precisely, the expected tiny changes in the direction of the spin axes of four gyroscopes contained in an Earth-orbiting satellite at a 400-mile altitude. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are very slightly warped by the presence of the Earth, and, more profoundly, how the Earth's rotation very slightly drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. GP-B is among the most thoroughly researched programs ever undertaken by NASA. This is the story of a scientific quest in which physicists and engineers have collaborated closely over many years. Inspired by their quest, they have invented a whole range of technologies that are already enlivening other branches of science and engineering. Launched April 20, 2004 , the GP-B program was managed for NASA by the Marshall Space Flight Center. Development of the GP-B is the responsibility of Stanford University along with major subcontractor Lockheed Martin Corporation. (Image credit to Russ Underwood, Lockheed Martin Corporation).
2000-01-01
In this photo, the Gravity Probe B (GP-B) space vehicle is being assembled at the Sunnyvale, California location of the Lockheed Martin Corporation. The GP-B is the relativity experiment developed at Stanford University to test two extraordinary predictions of Albert Einstein's general theory of relativity. The experiment will measure, very precisely, the expected tiny changes in the direction of the spin axes of four gyroscopes contained in an Earth-orbiting satellite at a 400-mile altitude. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are very slightly warped by the presence of the Earth, and, more profoundly, how the Earth's rotation very slightly drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. GP-B is among the most thoroughly researched programs ever undertaken by NASA. This is the story of a scientific quest in which physicists and engineers have collaborated closely over many years. Inspired by their quest, they have invented a whole range of technologies that are already enlivening other branches of science and engineering. Launched April 20, 2004 , the GP-B program was managed for NASA by the Marshall Space Flight Center. Development of the GP-B is the responsibility of Stanford University along with major subcontractor Lockheed Martin Corporation. (Image credit to Russ Underwood, Lockheed Martin Corporation).
The Gravity Probe B Experiment
Kolodziejczak, Jeffrey
2008-01-01
This presentation briefly describes the Gravity Probe B (GP-B) Experiment which is designed to measure parts of Einstein's general theory of relativity by monitoring gyroscope orientation relative to a distant guide star. To measure the miniscule angles predicted by Einstein's theory, it was necessary to build near-perfect gyroscopes that were approximately 50 million times more precise than the best navigational gyroscopes. A telescope mounted along the central axis of the dewar and spacecraft provided the experiment's pointing reference to a guide star. The telescope's image divide precisely split the star's beam into x-axis and y-axis components whose brightness could be compared. GP-B's 650-gallon dewar, kept the science instrument inside the probe at a cryogenic temperature for 17.3 months and also provided the thruster propellant for precision attitude and translation control. Built around the dewar, the GP-B spacecraft was a total-integrated system, comprising both the space vehicle and payload, dedicated as a single entity to experimentally testing predictions of Einstein's theory.
Timing system design and tests for the Gravity Probe B relativity mission
International Nuclear Information System (INIS)
Li, J; Keiser, G M; Ohshima, Y; Shestople, P; Lockhart, J M
2015-01-01
In this paper, we discuss the timing system design and tests for the NASA/Stanford Gravity Probe B (GP-B) relativity mission. The primary clock of GP-B, called the 16f o clock, was an oven-controlled crystal oscillator that produced a 16.368 MHz master frequency 3 . The 16f o clock and the 10 Hz data strobe, which was divided down from the 16f o clock, provided clock signals to all GP-B components and synchronized the data collection, transmission, and processing. The sampled data of science signals were stamped with the vehicle time, a counter of the 10 Hz data strobe. The time latency between the time of data sampling and the stamped vehicle time was compensated in the ground data processing. Two redundant global positioning system receivers onboard the GP-B satellite supplied an external reference for time transfer between the vehicle time and coordinated universal time (UTC), and the time conversion was established in the ground preprocessing of the telemetry timing data. The space flight operation showed that the error of time conversion between the vehicle time and UTC was less than 2 μs. Considering that the constant timing offsets were compensated in the ground processing of the GP-B science data, the time latency between the effective sampling time of GP-B science signals and the stamped vehicle time was verified to within 1 ms in the ground tests. (paper)
2003-01-01
The space vehicle for Gravity Probe B (GP-B) arrives at the launch site at Vandenburg Air Force Base. GP-B is the relativity experiment being developed at Stanford University to test two extraordinary predictions of Albert Einstein's general theory of relativity. The experiment will measure, very precisely, the expected tiny changes in the direction of the spin axes of four gyroscopes contained in an Earth-orbiting satellite at a 400-mile altitude. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are very slightly warped by the presence of the Earth, and, more profoundly, how the Earth's rotation very slightly drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. GP-B is among the most thoroughly researched programs ever undertaken by NASA. This is the story of a scientific quest in which physicists and engineers have collaborated closely over many years. Inspired by their quest, they have invented a whole range of technologies that are already enlivening other branches of science and engineering. Scheduled for launch in 2003 and managed for NASA by the Marshall Space Flight Center, development of the GP-B is the responsibility of Stanford University, with major subcontractor Lockheed Martin Corporation.
The Gravity Probe B Flight Dewar
2001-01-01
Gravity Probe B (GP-B) is the relativity experiment developed at Stanford University to test two extraordinary predictions of Albert Einstein's general theory of relativity. This photograph is of the Gravity Probe B flight dewar, a metal container made like a vacuum bottle that is used especially for storing liquefied gases, that will maintain the experiment at a temperature just above absolute zero, staying cold for two years. The experiment will measure, very precisely, the expected tiny changes in the direction of the spin axes of four gyroscopes contained in an Earth-orbiting satellite at 400-mile altitude. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are very slightly warped by the presence of the Earth, and, more profoundly, how the Earth's rotation very slightly drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. GP-B is among the most thoroughly researched programs ever undertaken by NASA. This is the story of a scientific quest in which physicists and engineers have collaborated closely over many years. Inspired by their quest, they have invented a whole range of technologies -- technologies that are already enlivening other branches of science and engineering. Launched in 2004 and managed for NASA by the Marshall Space Flight Center, development of the GP-B is the responsibility of Stanford University, with major subcontractor Lockheed Martin Corporation. (Photo Credit: Lockheed Martin Corporation/R. Underwood)
The Gravity Probe B experiment and early results
Energy Technology Data Exchange (ETDEWEB)
Conklin, John W [Stanford University (United States)], E-mail: johnwc@stanford.edu
2008-11-01
The NASA Gravity Probe B orbiting gyroscope test of General Relativity, launched from Vandenberg Air Force Base on 20 April, 2004 tests two consequences of Einstein's theory: 1) the predicted 6.6 arcs/yr geodetic effect due to the motion of the gyroscope through the curved space-time around the Earth; 2) the predicted 0.039 arcs/yr frame-dragging effect due to the rotating Earth. The mission required the development of many technologies that did not exist when experiment was conceived in 1960. Cryogenic gyroscopes with drift-rates 7 orders of magnitude better than the best inertial navigation gyroscopes, a < 1 marcs star tracking telescope, and other essential technologies were developed as a result of an intensive collaboration between Stanford physicists and engineers, NASA and industry. Gravity Probe B collected science data from August 27, 2004 through September 29, 2005. Analysis of the data began during the mission and is on-going. This paper describes the main features and challenges of the experiment and presents the preliminary results to date.
The Gravity Probe B experiment and early results
International Nuclear Information System (INIS)
Conklin, John W
2008-01-01
The NASA Gravity Probe B orbiting gyroscope test of General Relativity, launched from Vandenberg Air Force Base on 20 April, 2004 tests two consequences of Einstein's theory: 1) the predicted 6.6 arcs/yr geodetic effect due to the motion of the gyroscope through the curved space-time around the Earth; 2) the predicted 0.039 arcs/yr frame-dragging effect due to the rotating Earth. The mission required the development of many technologies that did not exist when experiment was conceived in 1960. Cryogenic gyroscopes with drift-rates 7 orders of magnitude better than the best inertial navigation gyroscopes, a < 1 marcs star tracking telescope, and other essential technologies were developed as a result of an intensive collaboration between Stanford physicists and engineers, NASA and industry. Gravity Probe B collected science data from August 27, 2004 through September 29, 2005. Analysis of the data began during the mission and is on-going. This paper describes the main features and challenges of the experiment and presents the preliminary results to date.
Artist's Concept of Gravity Probe-B
2002-01-01
Gravity Probe-B (GP-B) is the relativity experiment being developed at Stanford University to test two extraordinary predictions of Albert Einstein's general theory of relativity. The experiment will measure, very precisely, the expected tiny changes in the direction of the spin axes of four gyroscopes contained in an Earth-orbiting satellite at a 400-mile altitude. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are very slightly warped by the presence of the Earth, and, more profoundly, how the Earth's rotation very slightly drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. GP-B is among the most thoroughly researched programs ever undertaken by NASA. This is the story of a scientific quest in which physicists and engineers have collaborated closely over many years. Inspired by their quest, they have invented a whole range of technologies -- technologies that are already enlivening other branches of science and engineering. Scheduled for launch in 2003 and managed for NASA by Marshall Space Flight Center, development of GP-B is the responsibility of Stanford University, with major subcontractor Lockheed Martin Corporation.
Gravity Probe B Number 4 Gyro Inspected
2000-01-01
The Gravity Probe B (GP-B) is the relativity experiment developed at Stanford University to test two extraordinary predictions of Albert Einstein's general theory of relativity. The experiment will measure, very precisely, the expected tiny changes in the direction of the spin axes of four gyroscopes contained in an Earth-orbiting satellite at a 400-mile altitude. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are very slightly warped by the presence of the Earth, and, more profoundly, how the Earth's rotation very slightly drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. In this photograph, Stanford engineer, Chris Gray, is inspecting the number 4 gyro under monochromatic light. GP-B is among the most thoroughly researched programs ever undertaken by NASA. This is the story of a scientific quest in which physicists and engineers have collaborated closely over many years. Inspired by their quest, they have invented a whole range of technologies that are already enlivening other branches of science and engineering. Launched April 20, 2004 , the GP-B program was managed for NASA by the Marshall Space Flight Center. Development of the GP-B is the responsibility of Stanford University along with major subcontractor Lockheed Martin Corporation. (Image credit to Russ Leese, Stanford University.)
Gravity Probe B Completed With Solar Arrays
2004-01-01
In this photo, the Gravity Probe B (GP-B) space vehicle is completed during the solar array installation. The GP-B is the relativity experiment developed at Stanford University to test two extraordinary predictions of Albert Einstein's general theory of relativity. The experiment will measure, very precisely, the expected tiny changes in the direction of the spin axes of four gyroscopes contained in an Earth-orbiting satellite at a 400-mile altitude. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are very slightly warped by the presence of the Earth, and, more profoundly, how the Earth's rotation very slightly drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. GP-B is among the most thoroughly researched programs ever undertaken by NASA. This is the story of a scientific quest in which physicists and engineers have collaborated closely over many years. Inspired by their quest, they have invented a whole range of technologies that are already enlivening other branches of science and engineering. GP-B is scheduled for launch in April 2004 and managed for NASA by the Marshall Space Flight Center. Development of the GP-B is the responsibility of Stanford University along with major subcontractor Lockheed Martin Corporation. (Image credit to Russ Underwood, Lockheed Martin Corporation).
Modeling of micro thrusters for gravity probe B
Jones, Kenneth M.
1996-01-01
The concept of testing Einstein's general theory of relativity by means of orbiting gyroscopes was first proposed in 1959, which lead to the development of the Gravity Probe B experiment. Einstein's theory concerns the predictions of the relativistic precession of a gyroscope in orbit around earth. According to his theory, there will be two precessions due to the warping of space-time by the earth's gravitational field: the geodetic precession in the plane of the orbit, and the frame-dragging effect, in the direction of earth rotation. For a polar orbit, these components are orthogonal. In order to simplify the measurement of the precessions, Gravity Probe B (GP-B) will be placed in a circular polar orbit at 650 km, for which the predicted precessions will be 6.6 arcsec/year (geodetic) and 42 milli-arcsec/year (frame-dragging). As the gyroscope precesses, the orientation of its spin-axis will be measured with respect to the line-of-sight to Rigel, a star whose proper motion is known to be within the required accuracy. The line-of-sight to Rigel will be established using a telescope, and the orientation of the gyroscope spin axis will be measured using very sensitive SQUID (Superconducting Quantum Interference Device) magnetometers. The four gyroscopes will be coated with niobium. Below 2K, the niobium becomes superconducting and a dipole field will be generated which is precisely aligned with the gyroscope spin-axis. The change in orientation of these fields, as well as the spin-axis, is sensed by the SQUID magnetometers. In order to attain the superconducting temperatures for the gyroscopes and the SQUID's, the experiment package will be housed in a dewar filled with liquid helium. The helium flow through a GP-B micro thruster and into a vacuum is investigated using the Direct Simulation Monte Carlo method.
Gravity Probe B orbit determination
International Nuclear Information System (INIS)
Shestople, P; Ndili, A; Parkinson, B W; Small, H; Hanuschak, G
2015-01-01
The Gravity Probe B (GP-B) satellite was equipped with a pair of redundant Global Positioning System (GPS) receivers used to provide navigation solutions for real-time and post-processed orbit determination (OD), as well as to establish the relation between vehicle time and coordinated universal time. The receivers performed better than the real-time position requirement of 100 m rms per axis. Post-processed solutions indicated an rms position error of 2.5 m and an rms velocity error of 2.2 mm s −1 . Satellite laser ranging measurements provided independent verification of the GPS-derived GP-B orbit. We discuss the modifications and performance of the Trimble Advance Navigation System Vector III GPS receivers. We describe the GP-B precision orbit and detail the OD methodology, including ephemeris errors and the laser ranging measurements. (paper)
Gradiometry coexperiments to the gravity probe B and step missions
International Nuclear Information System (INIS)
Tapley, M.; Breakwell, J.; Everitt, C.W.F.; Vanpatten, R.; Worden, P.
1990-01-01
The Gravity Probe-B (GP-B) spacecraft, designed to test predictions of general relativity, will fly in the mid 1990s. It will carry four electrostatically suspended gyroscopes in a cryogenic environment and will have a drag-free control system to minimize disturbances on the gyroscopes. The Stanford Test of Equivalence Principle (STEP) spacecraft, to fly later, will carry a set of test masses under very similar conditions. The possibility of using differential measurements of the GP-B gyroscopes suspension forces and the STEP tests mass displacement readout to form single-axis gravity gradiometers is explored. It is shown that the noise in the suspension systems is sufficiently small in the relevant frequency range, and that enough information is collected to compensate for the spacecrafts' attitude motion. Finally, using Breakwell's flat-earth approximation, these experiments are compared to other geodesy experiments and predict the contribution they can make to the knowledge of the Earth's geopotential
Gravity Probe B Detector Mount Assembly
2004-01-01
In this photo, the Gravity Probe B (GP-B) detector mount assembly is shown in comparison to the size of a dime. The assembly is used to detect exactly how much starlight is coming through different beams from the beam splitter in the telescope. The measurements from the tiny chips inside are what keeps GP-B aimed at the guide star. The GP-B is the relativity experiment developed at Stanford University to test two extraordinary predictions of Albert Einstein's general theory of relativity. The experiment will measure, very precisely, the expected tiny changes in the direction of the spin axes of four gyroscopes contained in an Earth-orbiting satellite at a 400-mile altitude. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are very slightly warped by the presence of the Earth, and, more profoundly, how the Earth's rotation very slightly drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. GP-B is among the most thoroughly researched programs ever undertaken by NASA. This is the story of a scientific quest in which physicists and engineers have collaborated closely over many years. Inspired by their quest, they have invented a whole range of technologies that are already enlivening other branches of science and engineering. Launched April 20, 2004 , the GP-B program was managed for NASA by the Marshall Space Flight Center. Development of the GP-B is the responsibility of Stanford University along with major subcontractor Lockheed Martin Corporation. (Image credit to Paul Ehrensberger, Stanford University.)
Gravity Probe B spacecraft description
International Nuclear Information System (INIS)
Bennett, Norman R; Burns, Kevin; Katz, Russell; Kirschenbaum, Jon; Mason, Gary; Shehata, Shawky
2015-01-01
The Gravity Probe B spacecraft, developed, integrated, and tested by Lockheed Missiles and Space Company and later Lockheed Martin Corporation, consisted of structures, mechanisms, command and data handling, attitude and translation control, electrical power, thermal control, flight software, and communications. When integrated with the payload elements, the integrated system became the space vehicle. Key requirements shaping the design of the spacecraft were: (1) the tight mission timeline (17 months, 9 days of on-orbit operation), (2) precise attitude and translational control, (3) thermal protection of science hardware, (4) minimizing aerodynamic, magnetic, and eddy current effects, and (5) the need to provide a robust, low risk spacecraft. The spacecraft met all mission requirements, as demonstrated by dewar lifetime meeting specification, positive power and thermal margins, precision attitude control and drag-free performance, reliable communications, and the collection of more than 97% of the available science data. (paper)
Completed Gravity Probe B Undergoes Thermal Vacuum Testing
2000-01-01
The Gravity Probe B (GP-B) is the relativity experiment developed at Stanford University to test two extraordinary predictions of Albert Einstein's general theory of relativity. The experiment will measure, very precisely, the expected tiny changes in the direction of the spin axes of four gyroscopes contained in an Earth-orbiting satellite at a 400-mile altitude. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are very slightly warped by the presence of the Earth, and, more profoundly, how the Earth's rotation very slightly drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. In this photograph, the completed space vehicle is undergoing thermal vacuum environment testing. GP-B is among the most thoroughly researched programs ever undertaken by NASA. This is the story of a scientific quest in which physicists and engineers have collaborated closely over many years. Inspired by their quest, they have invented a whole range of technologies that are already enlivening other branches of science and engineering. Launched April 20, 2004 , the GP-B program was managed for NASA by the Marshall Space Flight Center. Development of the GP-B is the responsibility of Stanford University along with major subcontractor Lockheed Martin Corporation. (Image credit to Russ Underwood, Lockheed Martin Corporation.)
The Gravity Probe B Payload Hoisted by Crane
2001-01-01
The Gravity Probe B (GP-B) payload was hoisted by crane to the transportation truck in the W.W. Hansen Experimental Physics Laboratory in Stanford, California for shipment to the launch site at Vandenburg Air Force Base. GP-B is the relativity experiment being developed at Stanford University to test two extraordinary predictions of Albert Einstein's general theory of relativity. The experiment will measure, very precisely, the expected tiny changes in the direction of the spin axes of four gyroscopes contained in an Earth-orbiting satellite at a 400-mile altitude. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are very slightly warped by the presence of the Earth, and, more profoundly, how the Earth's rotation very slightly drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. GP-B is among the most thoroughly researched programs ever undertaken by NASA. This is the story of a scientific quest in which physicists and engineers have collaborated closely over many years. Inspired by their quest, they have invented a whole range of technologies that are already enlivening other branches of science and engineering. Launched April 20, 2004, the GP-B program was managed for NASA by the Marshall Space Flight Center. Development of the GP-B is the responsibility of Stanford University, along with major subcontractor Lockheed Martin Corporation. (Photo Credit: Stanford University)
Features of the Gravity Probe B Space Vehicle
Reeve, William; Green, Gaylord
2007-04-01
Space vehicle performance enabled successful relativity data collection throughout the Gravity Probe B mission. Precision pointing and drag-free translation control was maintained using proportional helium micro-thrusters. Electrical power was provided by rigid, double sided solar arrays. The 1.8 kelvin science instrument temperature was maintained using the largest cryogenic liquid helium dewar ever flown in space. The flight software successfully performed autonomous operations and safemode protection. Features of the Gravity Probe B Space Vehicle mechanisms include: 1) sixteen helium micro-thrusters, the first proportional thrusters flown in space, and large-orifice thruster isolation valves, 2) seven precision and high-authority mass trim mechanisms, 3) four non-pyrotechnic, highly reliable solar array deployment and release mechanism sets. Early incremental prototyping was used extensively to reduce spacecraft development risk. All spacecraft systems were redundant and provided multiple failure tolerance in critical systems. Lockheed Martin performed the spacecraft design, systems engineering, hardware and software integration, environmental testing and launch base operations, as well as on-orbit operations support for the Gravity Probe B space science experiment.
Gravity Probe B data system description
International Nuclear Information System (INIS)
Bennett, Norman R
2015-01-01
The Gravity Probe B data system, developed, integrated, and tested by Lockheed Missiles and Space Company, and later Lockheed Martin Corporation, included flight and ground command, control, and communications software. The development was greatly facilitated, conceptually and by the transfer of key personnel, through Lockheed’s earlier flight and ground test software development for the Hubble Space Telescope (HST). Key design challenges included the tight mission timeline (17 months, 9 days of on-orbit operation), the need to tune the system once on-orbit, and limited 2 Kbps real-time data rates and ground asset availability. The result was a completely integrated space vehicle and Stanford mission operations center, which successfully collected and archived 97% of the ‘guide star valid’ data to support the science analysis. Lessons learned and incorporated from the HST flight software development and on-orbit support experience, and Lockheed’s independent research and development effort, will be discussed. (paper)
Gravity Probe B Experiment and Gravitomagnetism
Veto, B.
2010-01-01
Gravitomagnetism is a low velocity and weak gravitational field approximation of general relativity. It provides a simple approach to post-Newtonian gravitational phenomena via electromagnetic analogy. Intended for advanced undergraduate students, the present paper applies gravitomagnetism to the quantitative study of the geodetic precession and…
Gravity Probe B data analysis: II. Science data and their handling prior to the final analysis
International Nuclear Information System (INIS)
Silbergleit, A S; Conklin, J W; Heifetz, M I; Holmes, T; Li, J; Mandel, I; Solomonik, V G; Stahl, K; P W Worden Jr; Everitt, C W F; Adams, M; Berberian, J E; Bencze, W; Clarke, B; Al-Jadaan, A; Keiser, G M; Kozaczuk, J A; Al-Meshari, M; Muhlfelder, B; Salomon, M
2015-01-01
The results of the Gravity Probe B relativity science mission published in Everitt et al (2011 Phys. Rev. Lett. 106 221101) required a rather sophisticated analysis of experimental data due to several unexpected complications discovered on-orbit. We give a detailed description of the Gravity Probe B data reduction. In the first paper (Silbergleit et al Class. Quantum Grav. 22 224018) we derived the measurement models, i.e., mathematical expressions for all the signals to analyze. In the third paper (Conklin et al Class. Quantum Grav. 22 224020) we explain the estimation algorithms and their program implementation, and discuss the experiment results obtained through data reduction. This paper deals with the science data preparation for the main analysis yielding the relativistic drift estimates. (paper)
DC electrostatic gyro suspension system for the Gravity Probe B experiment
Wu, Chang-Huei
1994-12-01
The Gravity Probe B experiment is a satellite-based experiment primarily designed to test two aspects of Einstein's General Theory of Relativity by observing the spin axis drift of near-perfect gyroscopes in a 650-km circular polar orbit. The goal of this experiment is to measure the drift angles to an accuracy of 0.3 milli-arcsec after one year in orbit. As a result, electrostatically suspended free-spinning gyroscopes operating at a very low temperature became the final choice for their ultra-low Newtonian torque-induced drift rate. The Conventional AC current-driven suspension system faces two fundamental difficulties for ground gyro testing. Field emission causes rotor charging and arcing with an imperfect electrode or rotor surfaces because the electric field intensity needed to support a solid rotor in the 1-g field is more than 107 V/m. The system not only becomes unstable at a high rotor charge, which can be more than 500 volts, but may also lose control in case of arcing. Both the high voltage AC suspension signal and the high frequency (1 MHz) signal for rotor position sensing interfere with the superconducting SQUID magnetometer for spin axis readout through inductive coupling. These problems were resolved by using DC voltage to generate a suspension force and a low frequency position sensor. In addition to the Input/Output linearization algorithm developed to remove the system nonlinearity for global stability and dynamic performance, we also minimized the electric field intensity to reduce rotor charging. Experimental results verified the desired global stability and satisfactory dynamic performance. The problem of rotor charging is virtually eliminated. More importantly, the DC system is compatible with the SQUID readout system in the Science Mission configuration. Consequently, experiments in low magnetic field at a sub-micro-gauss level for SQUID design verification and trapped flux distribution study were finally realizable in ground environment
Gravity Probe-B (GP-B) Mission and Tracking, Telemetry and Control Subsystem Overview
Kennedy, Paul; Bell, Joseph L. (Technical Monitor)
2001-01-01
The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) in Huntsville, Alabama will launch the Gravity Probe B (GP-B) space experiment in the Fall of 2002. The GP-B spacecraft was developed to prove Einstein's theory of General Relativity. This paper will provide an overview of the GPB mission and will discuss the design, and test of the spacecraft Tracking, Telemetry and Control (TT&C) subsystem which incorporates NASA's latest generation standard transponder for use with the NASA Tracking and Data Relay Satellite System (TDRSS).
Salomon, M; Conklin, J W; Kozaczuk, J; Berberian, J E; Keiser, G M; Silbergleit, A S; Worden, P; Santiago, D I
2011-12-01
In this paper, we present a method to measure the frequency and the frequency change rate of a digital signal. This method consists of three consecutive algorithms: frequency interpolation, phase differencing, and a third algorithm specifically designed and tested by the authors. The succession of these three algorithms allowed a 5 parts in 10(10) resolution in frequency determination. The algorithm developed by the authors can be applied to a sampled scalar signal such that a model linking the harmonics of its main frequency to the underlying physical phenomenon is available. This method was developed in the framework of the gravity probe B (GP-B) mission. It was applied to the high frequency (HF) component of GP-B's superconducting quantum interference device signal, whose main frequency f(z) is close to the spin frequency of the gyroscopes used in the experiment. A 30 nHz resolution in signal frequency and a 0.1 pHz/s resolution in its decay rate were achieved out of a succession of 1.86 s-long stretches of signal sampled at 2200 Hz. This paper describes the underlying theory of the frequency measurement method as well as its application to GP-B's HF science signal.
VLBI FOR GRAVITY PROBE B. VII. THE EVOLUTION OF THE RADIO STRUCTURE OF IM PEGASI
International Nuclear Information System (INIS)
Bietenholz, M. F.; Bartel, N.; Ransom, R. R.; Lebach, D. E.; Ratner, M. I.; Shapiro, I. I.
2012-01-01
We present measurements of the total radio flux density as well as very long baseline interferometry images of the star, IM Pegasi, which was used as the guide star for the NASA/Stanford relativity mission Gravity Probe B. We obtained flux densities and images from 35 sessions of observations at 8.4 GHz (λ = 3.6 cm) between 1997 January and 2005 July. The observations were accurately phase-referenced to several extragalactic reference sources, and we present the images in a star-centered frame, aligned by the position of the star as derived from our fits to its orbital motion, parallax, and proper motion. Both the flux density and the morphology of IM Peg are variable. For most sessions, the emission region has a single-peaked structure, but 25% of the time, we observed a two-peaked (and on one occasion perhaps a three-peaked) structure. On average, the emission region is elongated by 1.4 ± 0.4 mas (FWHM), with the average direction of elongation being close to that of the sky projection of the orbit normal. The average length of the emission region is approximately equal to the diameter of the primary star. No significant correlation with the orbital phase is found for either the flux density or the direction of elongation, and no preference for any particular longitude on the star is shown by the emission region.
Relative Pose Estimation Algorithm with Gyroscope Sensor
Directory of Open Access Journals (Sweden)
Shanshan Wei
2016-01-01
Full Text Available This paper proposes a novel vision and inertial fusion algorithm S2fM (Simplified Structure from Motion for camera relative pose estimation. Different from current existing algorithms, our algorithm estimates rotation parameter and translation parameter separately. S2fM employs gyroscopes to estimate camera rotation parameter, which is later fused with the image data to estimate camera translation parameter. Our contributions are in two aspects. (1 Under the circumstance that no inertial sensor can estimate accurately enough translation parameter, we propose a translation estimation algorithm by fusing gyroscope sensor and image data. (2 Our S2fM algorithm is efficient and suitable for smart devices. Experimental results validate efficiency of the proposed S2fM algorithm.
International Nuclear Information System (INIS)
Lebach, D. E.; Ratner, M. I.; Shapiro, I. I.; Bartel, N.; Bietenholz, M. F.; Lederman, J. I.; Ransom, R. R.; Campbell, R. M.; Gordon, D.; Lestrade, J.-F.
2012-01-01
When very long baseline interferometry (VLBI) observations are used to determine the position or motion of a radio source relative to reference sources nearby on the sky, the astrometric information is usually obtained via (1) phase-referenced maps or (2) parametric model fits to measured fringe phases or multiband delays. In this paper, we describe a 'merged' analysis technique which combines some of the most important advantages of these other two approaches. In particular, our merged technique combines the superior model-correction capabilities of parametric model fits with the ability of phase-referenced maps to yield astrometric measurements of sources that are too weak to be used in parametric model fits. We compare the results from this merged technique with the results from phase-referenced maps and from parametric model fits in the analysis of astrometric VLBI observations of the radio-bright star IM Pegasi (HR 8703) and the radio source B2252+172 nearby on the sky. In these studies we use central-core components of radio sources 3C 454.3 and B2250+194 as our positional references. We obtain astrometric results for IM Peg with our merged technique even when the source is too weak to be used in parametric model fits, and we find that our merged technique yields astrometric results superior to the phase-referenced mapping technique. We used our merged technique to estimate the proper motion and other astrometric parameters of IM Peg in support of the NASA/Stanford Gravity Probe B mission.
A high-energy (35-500 MeV) proton monitor for the Gravity Probe-B Mission
Energy Technology Data Exchange (ETDEWEB)
McKenna-Lawlor, S. E-mail: stil@may.ie; Rusznyak, Peter; Buchman, Sasha; Shestople, Paul; Thatcher, John
2003-02-11
An innovative fault tolerant, high-energy particle monitor designed to record protons in the range 35-500 MeV when in polar orbit aboard NASA's Gravity Probe B spacecraft, is described. This device, which is configured to provide continuous, reliable operation in the hostile particle environment traversed by the spacecraft, can potentially be used either as an onboard monitor or as a scientific experiment.
A superconducting gyroscope to test Einstein's general theory of relativity
Everitt, C. W. F.
1978-01-01
Schiff (1960) proposed a new test of general relativity based on measuring the precessions of the spin axes of gyroscopes in earth orbit. Since 1963 a Stanford research team has been developing an experiment to measure the two effects calculated by Schiff. The gyroscope consists of a uniform sphere of fused quartz 38 mm in diameter, coated with superconductor, electrically suspended and spinning at about 170 Hz in vacuum. The paper describes the proposed flight apparatus and the current state of development of the gyroscope, including techniques for manufacturing and measuring the gyro rotor and housing, generating ultralow magnetic fields, and mechanizing the readout.
Gyroscope precession in special and general relativity from basic principles
Jonsson, Rickard M.
2007-05-01
In special relativity a gyroscope that is suspended in a torque-free manner will precess as it is moved along a curved path relative to an inertial frame S. We explain this effect, which is known as Thomas precession, by considering a real grid that moves along with the gyroscope, and that by definition is not rotating as observed from its own momentary inertial rest frame. From the basic properties of the Lorentz transformation we deduce how the form and rotation of the grid (and hence the gyroscope) will evolve relative to S. As an intermediate step we consider how the grid would appear if it were not length contracted along the direction of motion. We show that the uncontracted grid obeys a simple law of rotation. This law simplifies the analysis of spin precession compared to more traditional approaches based on Fermi transport. We also consider gyroscope precession relative to an accelerated reference frame and show that there are extra precession effects that can be explained in a way analogous to the Thomas precession. Although fully relativistically correct, the entire analysis is carried out using three-vectors. By using the equivalence principle the formalism can also be applied to static spacetimes in general relativity. As an example, we calculate the precession of a gyroscope orbiting a static black hole.
Seifollahi, Alireza
It is said that future of the world is based on space exploration which leads us to think more about low cost and light weight instruments. Cheap and sensitive instruments should be de-signed and replace the expensive ones. One of the required instruments in space ships is gyroscope controls the direction of space ship. In this article I am going to give an idea to use optical properties in a new gyroscope which will be cheaper as well as more sensitive in com-pare with most of the being used normal gyroscope nowadays. This instrument uses an optical system to measure the angular changes in the direction of a space craft movements in any of the three axels. Any movement, even very small one, will move a crystal bulb which is lashed by some narrow elastic bands in a fixed box surrounded by three optical sources and light meters. Light meters measure the attitude and the angel of changes in the light beams going through the bulb which is related to the amount of changes in the space craft directions. The system will be very sensitive even against movement around its access. As an electro digital device in connection to a Main Process Unit (MPU) it can be used in Stability Augmentation System (SAS) in a space ship. The sensitivity rate of the instrument will be based on the quality and sensitivity of the light meters.
Microelectromechanical gyroscope
Garcia, Ernest J.
1999-01-01
A gyroscope powered by an engine, all fabricated on a common substrate in the form of an integrated circuit. Preferably, both the gyroscope and the engine are fabricated in the micrometer domain, although in some embodiments of the present invention, the gyroscope can be fabricated in the millimeter domain. The engine disclosed herein provides torque to the gyroscope rotor for continuous rotation at varying speeds and direction. The present invention is preferably fabricated of polysilicon or other suitable materials on a single wafer using surface micromachining batch fabrication techniques or millimachining techniques that are well known in the art. Fabrication of the present invention is preferably accomplished without the need for assembly of multiple wafers which require alignment and bonding, and without piece-part assembly.
2004-01-01
KENNEDY SPACE CENTER, FLA. The Gravity Probe B spacecraft, atop a Boeing Delta II vehicle, launches at 12:57:24 p.m. EDT from Space Launch Complex 2 at Vandenberg Air Force Base, Calif. Gravity Probe B is the relativity gyroscope experiment being developed by NASA and Stanford University to test two extraordinary, unverified predictions of Albert Einstein's general theory of relativity.
Topological Gyroscopic Metamaterials
Nash, Lisa Michelle
Topological materials are generally insulating in their bulk, with protected conducting states on their boundaries that are robust against disorder and perturbation of material property. The existence of these conducting edge states is characterized by an integer topological invariant. Though the phenomenon was first discovered in electronic systems, recent years have shown that topological states exist in classical systems as well. In this thesis we are primarily concerned with the topological properties of gyroscopic materials, which are created by coupling networks of fast-spinning objects. Through a series of simulations, numerical calculations, and experiments, we show that these materials can support topological edge states. We find that edge states in these gyroscopic metamaterials bear the hallmarks of topology related to broken time reversal symmetry: they transmit excitations unidirectionally and are extremely robust against experimental disorder. We also explore requirements for topology by studying several lattice configurations and find that topology emerges naturally in gyroscopic systems.A simple prescription can be used to create many gyroscopic lattices. Though many of our gyroscopic networks are periodic, we explore amorphous point-sets and find that topology also emerges in these networks.
Influences of optical-spectrum errors on excess relative intensity noise in a fiber-optic gyroscope
Zheng, Yue; Zhang, Chunxi; Li, Lijing
2018-03-01
The excess relative intensity noise (RIN) generated from broadband sources degrades the angular-random-walk performance of a fiber-optic gyroscope dramatically. Many methods have been proposed and managed to suppress the excess RIN. However, the properties of the excess RIN under the influences of different optical errors in the fiber-optic gyroscope have not been systematically investigated. Therefore, it is difficult for the existing RIN-suppression methods to achieve the optimal results in practice. In this work, the influences of different optical-spectrum errors on the power spectral density of the excess RIN are theoretically analyzed. In particular, the properties of the excess RIN affected by the raised-cosine-type ripples in the optical spectrum are elaborately investigated. Experimental measurements of the excess RIN corresponding to different optical-spectrum errors are in good agreement with our theoretical analysis, demonstrating its validity. This work provides a comprehensive understanding of the properties of the excess RIN under the influences of different optical-spectrum errors. Potentially, it can be utilized to optimize the configurations of the existing RIN-suppression methods by accurately evaluating the power spectral density of the excess RIN.
GINGER (Gyroscopes IN General Relativity), a ring lasers array to measure the Lense-Thirring effect
Di Virgilio, Angela D. V.
The purpose of the GINGER is to perform the first test of general relativity (not considering the gravitational redshift measurements) in a terrestrial laboratory, using light as a probe. The experiment will complement the ones in space, performed or under way, with an entirely different technique and at a far lower cost. The methodology is based on ring-lasers, which are extremely accurate rotation sensors and can not only sense purely kinematical rotations (Sagnac effect accounting for the Earth rotation, polar motion of the terrestrial axis, local rotational movements of the laboratory due to the Earth crust dynamics...), but also general relativistic contributions such as the de Sitter effect (coupling between the gravito-electric field of the earth and the kinematical rotation) and the Lense-Thirring effect (inertial frame dragging due to the angular momentum of the earth). In order to reveal the latter effects, ring-laser response must be improved to be able to measure the effective rotation vector (kinematic plus GR terms) with an accuracy of 1 part in 109 or better. This is a challenging technological aspect, which however has been accurately taken into account by designing a system of ring lasers that will be implemented in this project. A ring laser have been installed inside the underground laboratory of GranSasso, with the purpose to see if an underground location is the right choice for GINGER. The apparatus and the preliminary results will be discussed.
Silicon micromachined vibrating gyroscopes
Voss, Ralf
1997-09-01
This work gives an overview of silicon micromachined vibrating gyroscopes. Market perspectives and fields of application are pointed out. The advantage of using silicon micromachining is discussed and estimations of the desired performance, especially for automobiles are given. The general principle of vibrating gyroscopes is explained. Vibrating silicon gyroscopes can be divided into seven classes. for each class the characteristic principle is presented and examples are given. Finally a specific sensor, based on a tuning fork for automotive applications with a sensitivity of 250(mu) V/degrees is described in detail.
Model Design of Piezoelectric Micromachined Modal Gyroscope
Directory of Open Access Journals (Sweden)
Xiaojun Hu
2011-01-01
Full Text Available This paper reports a novel kind of solid-state microgyroscope, which is called piezoelectric micromachined modal gyroscope (PMMG. PMMG has large stiffness and robust resistance to shake and strike because there is no evident mass-spring component in its structure. This work focused on quantitative optimization of the gyroscope, which is still blank for such gyroscope. The modal analysis by the finite element method (FEM was firstly conducted. A set of quantitative indicators were developed to optimize the operation mode. By FEM, the harmonic analysis was conducted to find the way to efficiently actuate the operational mode needed. The optimal configuration of driving electrodes was obtained. At last, the Coriolis analysis was conducted to show the relation between angular velocity and differential output voltage by the Coriolis force under working condition. The results obtained in this paper provide theoretical basis for realizing this novel kind of micromachined gyroscope.
Gyroscope Technology and Applications: A Review in the Industrial Perspective
Directory of Open Access Journals (Sweden)
Vittorio M. N. Passaro
2017-10-01
Full Text Available This paper is an overview of current gyroscopes and their roles based on their applications. The considered gyroscopes include mechanical gyroscopes and optical gyroscopes at macro- and micro-scale. Particularly, gyroscope technologies commercially available, such as Mechanical Gyroscopes, silicon MEMS Gyroscopes, Ring Laser Gyroscopes (RLGs and Fiber-Optic Gyroscopes (FOGs, are discussed. The main features of these gyroscopes and their technologies are linked to their performance.
GYROSCOPIC MANAGEMENT AND GENERATION Y
Directory of Open Access Journals (Sweden)
Orhei Loredana
2012-12-01
Full Text Available In the professional field of business and management there is still little research done on the possibility if the Generation Y members (born between 1980 and 2000, which are the managers off the future, need a different approach in education and training to be prepared for the future. The authors will explain how a new didactical approach in business and management called â€œGyroscopic Managementâ€ can prepare these new managers to be of added value for the business. This specific approach was the start in 2007 of a specific (international HRQM Bachelor study programme at Arnhem Business School, HAN University in the Netherlands. During this study programme, students are confronting this specific training and didactical approach with characteristics as self-reliance, self-study, and Socratic dialogue, ethical and â€œgyroscopicâ€ management. The programme has a clear vision and mission and didactical approach that triggers the above-mentioned elements. The approach focuses on the need for development of specific competencies like â€œIntercultural adaptabilityâ€, â€œInternational business awarenessâ€ and â€œSocial entrepreneurshipâ€ as added to the existing competencies needed for a Bachelor level in business and management education. As researchers, lecturers and trainers, the authors used and researched this approach during many lectures, seminars, trainings and workshops in the last years at Universities in Romania and The Netherlands. The authors present the characteristics of the members of the new Y generation and relate them to main elements of gyroscopic management as practice and the results of this practice for students. For this, the authors did a so-called â€œGrounded action researchâ€, from 2009 until 2012, among students of business and management studies. Further, the research was supported by focus groups over the same period. The authors have the opinion that this research is
The development of micro-gyroscope technology
International Nuclear Information System (INIS)
Liu, Kai; Zhang, Weiping; Chen, Wenyuan; Li, Kai; Dai, Fuyan; Cui, Feng; Wu, Xiaosheng; Ma, Gaoyin; Xiao, Qijun
2009-01-01
This review reports an overview and development of micro-gyroscope. The review first presents different types of micro-gyroscopes. Micro-gyroscopes in this review are categorized into Coriolis gyroscope, levitated rotor gyroscope, Sagnac gyroscope, nuclear magnetic resonance (NMR) gyroscope according to the working principle. Different principles, structures, materials, fabrications and control technologies of micro-gyroscopes are analyzed. This review compares different classes of gyroscopes in the aspects such as fabrication method, detection axis, materials, size and so on. Finally, the review evaluates the key technologies on how to improve the precision and anti-jamming ability and to extend the available applications of the gyroscopes in the market and patents as well. (topical review)
Ring mirror fiber laser gyroscope
Shalaby, Mohamed Y.; Khalil, Kamal; Afifi, Abdelrahman E.; Khalil, Diaa
2017-02-01
In this work we present a new architecture for a laser gyroscope based on the use of a Sagnac fiber loop mirror. The proposed system has the unique property that its scale factor can be increased by increasing the gain of the optical amplifier used in the system as demonstrated experimentally using standard single mode fiber and explained physically by the system operation. The proposed gyroscope system is also capable of identifying the direction of rotation. This new structure opens the door for a new category of low cost optical gyroscopes.
Non-driven micromechanical gyroscopes and their applications
Zhang, Fuxue; Wang, Guosheng
2018-01-01
This book comprehensively and systematically introduces readers to the theories, structures, performance and applications of non-driven mechanical and non-driven micromechanical gyroscopes. The book is divided into three parts, the first of which mainly addresses mathematic models, precision, performance and operating error in non-driven mechanical gyroscopes. The second part focuses on the operating theory, error, phase shift and performance experiments involving non-driven micromechanical gyroscopes in rotating flight carriers, while the third part shares insights into the application of non-driven micromechanical gyroscopes in control systems for rotating flight carriers. The book offers a unique resource for all researchers and engineers who are interested in the use of inertial devices and automatic control systems for rotating flight carriers. It can also serve as a reference book for undergraduates, graduates and instructors in related fields at colleges and universities.
Fiberless Optical Gyroscope, Phase II
National Aeronautics and Space Administration — We propose a radical new approach for to the design and fabrication of a fiber-less Interferometric Optical Gyroscope (IOG) that enables the production of a...
Coriolis vibratory gyroscopes theory and design
Apostolyuk, Vladislav
2016-01-01
This book provides the latest theoretical analysis and design methodologies of different types of Coriolis vibratory gyroscopes (CVG). Together, the chapters analyze different types of sensitive element designs and their kinematics, derivation of motion equations, analysis of sensitive elements dynamics in modulated and demodulated signals, calculation and optimization of main performance characteristics, and signal processing and control. Essential aspects of numerical simulation of CVG using Simulink® are also covered. This is an ideal book for graduate students, researchers, and engineers working in fields that require gyroscope application, including but not limited to: inertial sensors and systems, automotive and consumer electronics, small unmanned aircraft control systems, personal mobile navigation systems and related software development, and augmented and virtual reality systems.
What forces act in relativistic gyroscope precession?
Semerák, Oldrich
1996-11-01
The translation of the relativistic motion into the language of forces, proposed by the author (1995, Nuovo Cimento B 110 973), is employed to interpret the gyroscope precession in general relativity. The precession is referred to the comoving Frenet triad built up along the projection of the gyroscope's trajectory onto the 3-space of the local hypersurface-orthogonal observer. The contributions of the centrifugal, the gravitational and the dragging + Coriolis forces are identified respectively with the Thomas, the geodetic, and the gravitomagnetic components of precession. Explicit expressions are given for several simple types of motion in the Kerr (or simpler) field in order to show that the general formulae obtained are not only very simple, but also yield clear results in accord with intuition in concrete situations.
Smith, David D.
2015-01-01
Next-generation space missions are currently constrained by existing spacecraft navigation systems which are not fully autonomous. These systems suffer from accumulated dead-reckoning errors and must therefore rely on periodic corrections provided by supplementary technologies that depend on line-of-sight signals from Earth, satellites, or other celestial bodies for absolute attitude and position determination, which can be spoofed, incorrectly identified, occluded, obscured, attenuated, or insufficiently available. These dead-reckoning errors originate in the ring laser gyros themselves, which constitute inertial measurement units. Increasing the time for standalone spacecraft navigation therefore requires fundamental improvements in gyroscope technologies. One promising solution to enhance gyro sensitivity is to place an anomalous dispersion or fast light material inside the gyro cavity. The fast light essentially provides a positive feedback to the gyro response, resulting in a larger measured beat frequency for a given rotation rate as shown in figure 1. Game Changing Development has been investing in this idea through the Fast Light Optical Gyros (FLOG) project, a collaborative effort which began in FY 2013 between NASA Marshall Space Flight Center (MSFC), the U.S. Army Aviation and Missile Research, Development, and Engineering Center (AMRDEC), and Northwestern University. MSFC and AMRDEC are working on the development of a passive FLOG (PFLOG), while Northwestern is developing an active FLOG (AFLOG). The project has demonstrated new benchmarks in the state of the art for scale factor sensitivity enhancement. Recent results show cavity scale factor enhancements of approx.100 for passive cavities.
The Development of Micromachined Gyroscope Structure and Circuitry Technology
Directory of Open Access Journals (Sweden)
Dunzhu Xia
2014-01-01
Full Text Available This review surveys micromachined gyroscope structure and circuitry technology. The principle of micromachined gyroscopes is first introduced. Then, different kinds of MEMS gyroscope structures, materials and fabrication technologies are illustrated. Micromachined gyroscopes are mainly categorized into micromachined vibrating gyroscopes (MVGs, piezoelectric vibrating gyroscopes (PVGs, surface acoustic wave (SAW gyroscopes, bulk acoustic wave (BAW gyroscopes, micromachined electrostatically suspended gyroscopes (MESGs, magnetically suspended gyroscopes (MSGs, micro fiber optic gyroscopes (MFOGs, micro fluid gyroscopes (MFGs, micro atom gyroscopes (MAGs, and special micromachined gyroscopes. Next, the control electronics of micromachined gyroscopes are analyzed. The control circuits are categorized into typical circuitry and special circuitry technologies. The typical circuitry technologies include typical analog circuitry and digital circuitry, while the special circuitry consists of sigma delta, mode matching, temperature/quadrature compensation and novel special technologies. Finally, the characteristics of various typical gyroscopes and their development tendency are discussed and investigated in detail.
Basic relativity. An introductory essay
Energy Technology Data Exchange (ETDEWEB)
Hrasko, Peter [Pecs Univ. (Hungary)
2011-07-01
This Brief presents a new way of introducing relativity theory, in which perplexing relativistic effects such as time dilation and Lorentz contraction are explained prior to the discussion of Lorentz-transformation. The notion of relativistic mass is shown to contradict the spirit of relativity theory and the true significance of the mass-energy relation is contrasted with the popular view of it. The author discusses the twin paradox from the point of view of both siblings. Last but not least, the fundamentals of general relativity are described, including the recent Gravity Probe B experiment. (orig.)
Basic relativity. An introductory essay
International Nuclear Information System (INIS)
Hrasko, Peter
2011-01-01
This Brief presents a new way of introducing relativity theory, in which perplexing relativistic effects such as time dilation and Lorentz contraction are explained prior to the discussion of Lorentz-transformation. The notion of relativistic mass is shown to contradict the spirit of relativity theory and the true significance of the mass-energy relation is contrasted with the popular view of it. The author discusses the twin paradox from the point of view of both siblings. Last but not least, the fundamentals of general relativity are described, including the recent Gravity Probe B experiment. (orig.)
Basic Relativity An Introductory Essay
Hraskó, Péter
2011-01-01
This Brief presents a new way of introducing relativity theory, in which perplexing relativistic effects such as time dilation and Lorentz contraction are explained prior to the discussion of Lorentz-transformation. The notion of relativistic mass is shown to contradict the spirit of relativity theory and the true significance of the mass-energy relation is contrasted with the popular view of it. The author discusses the twin paradox from the point of view of both siblings. Last but not least, the fundamentals of general relativity are described, including the recent Gravity Probe B experiment.
GEC Ferranti piezo vibratory gyroscope
Nuttall, J. D.
1993-01-01
Prototypes of a piezo-electric vibratory angular rate transducer (gyroscope) (PVG) have been constructed and evaluated. The construction is on the lines suggested by Burdess. The sensitive element is a cylinder of radially poled piezo-electric ceramic. The cylinder is metallized inside and out, and the outer metallization is divided into eight electrodes. The metallization on the inside is earthed. A phase locked loop, using pairs of the electrodes, causes the cylinder to vibrate in one of its two fundamental, degenerate modes. In the presence of rotation, some of the vibration is coupled into the outer mode. This can be detected, or suppressed with a closed-up technique and provides a measure of rotation rate. The gyroscope provides a number of advantages over rotating mass and optical instruments: low size and mass, lower power consumption, potentially high reliability, potentially good dormancy, low cost and high maximum rate.
Gyroscopic management as added value for management
John Vinke
2012-01-01
In recent publications in International Journals in 2010 and 2011, I described the phenomenon of a new approach to education and training called ‘Gyroscopic Management’ (See list publications). To give the reader an insight and overview of this, I will introduce and explain this gyroscopic
Carbon Nanotube Tape Vibrating Gyroscope
Tucker, Dennis Stephen (Inventor)
2016-01-01
A vibrating gyroscope includes a piezoelectric strip having length and width dimensions. The piezoelectric strip includes a piezoelectric material and carbon nanotubes (CNTs) substantially aligned and polled along the strip's length dimension. A spindle having an axis of rotation is coupled to the piezoelectric strip. The axis of rotation is parallel to the strip's width dimension. A first capacitance sensor is mechanically coupled to the spindle for rotation therewith. The first capacitance sensor is positioned at one of the strip's opposing ends and is spaced apart from one of the strip's opposing faces. A second capacitance sensor is mechanically coupled to the spindle for rotation therewith. The second capacitance sensor is positioned at another of the strip's opposing ends and is spaced apart from another of the strip's opposing faces. A voltage source applies an AC voltage to the piezoelectric strip.
Integrated microelectromechanical gyroscope under shock loads
Nesterenko, T. G.; Koleda, A. N.; Barbin, E. S.
2018-01-01
The paper presents a new design of a shock-proof two-axis microelectromechanical gyroscope. Without stoppers, the shock load enables the interaction between the silicon sensor elements. Stoppers were installed in the gyroscope to prevent the contact interaction between electrodes and spring elements with fixed part of the sensor. The contact of stoppers occurs along the plane, thereby preventing the system from serious contact stresses. The shock resistance of the gyroscope is improved by the increase in its eigenfrequency at which the contact interaction does not occur. It is shown that the shock load directed along one axis does not virtually cause the movement of sensing elements along the crosswise axes. Maximum stresses observed in the proposed gyroscope at any loading direction do not exceed the value allowable for silicon.
MEMS Gyroscope with Interferometric Detection, Phase II
National Aeronautics and Space Administration — The proposed innovation is a novel MEMS gyroscope that uses micro-interferometric detection to measure the motion of the proof mass. Using an interferometric...
Nonlinear oscillations in coriolis based gyroscopes
Directory of Open Access Journals (Sweden)
Dag Kristiansen
1999-01-01
Full Text Available In this paper we model and analyze nonlinear oscillations which are known to exist in some Coriolis based gyroscopes due to large amplitude excitation in the drive loop. A detailed derivation of a dynamic model for a cylinder gyroscope which includes geometric nonlinearities is given, and energy transfer between the system's modes are analyzed using perturbation theory and by proposing a simplified model. The model is also simulated, and the results are shown to give an accurate description of the experimental results. This work is done in order to gain a better understanding of the gyroscope's dynamics, and is intended to be a starting point for designing nonlinear observers and vibration controllers for the gyroscope in order to increase the performance.
Fabrication of a novel quartz micromachined gyroscope
Xie, Liqiang; Xing, Jianchun; Wang, Haoxu; Wu, Xuezhong
2015-04-01
A novel quartz micromachined gyroscope is proposed in this paper. The novel gyroscope is realized by quartz anisotropic wet etching and 3-dimensional electrodes deposition. In the quartz wet etching process, the quality of Cr/Au mask films affecting the process are studied by experiment. An excellent mask film with 100 Å Cr and 2000 Å Au is achieved by optimization of experimental parameters. Crystal facets after etching seriously affect the following sidewall electrodes deposition process and the structure's mechanical behaviours. Removal of crystal facets is successfully implemented by increasing etching time based on etching rate ratios between facets and crystal planes. In the electrodes deposition process, an aperture mask evaporation method is employed to prepare electrodes on 3-dimensional surfaces of the gyroscope structure. The alignments among the aperture masks are realized by the ABM™ Mask Aligner System. Based on the processes described above, a z-axis quartz gyroscope is fabricated successfully.
High resolution capacitance detection circuit for rotor micro-gyroscope
Directory of Open Access Journals (Sweden)
Ming-Yuan Ren
2014-03-01
Full Text Available Conventional methods for rotor position detection of micro-gyroscopes include common exciting electrodes (single frequency and common sensing electrodes (frequency multiplex, but they have encountered some problems. So we present a high resolution and low noise pick-off circuit for micro-gyroscopes which utilizes the time multiplex method. The detecting circuit adopts a continuous-time current sensing circuit for capacitance measurement, and its noise analysis of the charge amplifier is introduced. The equivalent output noise power spectral density of phase-sensitive demodulation is 120 nV/Hz1/2. Tests revealed that the whole circuitry has a relative capacitance resolution of 1 × 10−8.
Design, Fabrication, and Modeling of a Novel Dual-Axis Control Input PZT Gyroscope.
Chang, Cheng-Yang; Chen, Tsung-Lin
2017-10-31
Conventional gyroscopes are equipped with a single-axis control input, limiting their performance. Although researchers have proposed control algorithms with dual-axis control inputs to improve gyroscope performance, most have verified the control algorithms through numerical simulations because they lacked practical devices with dual-axis control inputs. The aim of this study was to design a piezoelectric gyroscope equipped with a dual-axis control input so that researchers may experimentally verify those control algorithms in future. Designing a piezoelectric gyroscope with a dual-axis control input is more difficult than designing a conventional gyroscope because the control input must be effective over a broad frequency range to compensate for imperfections, and the multiple mode shapes in flexural deformations complicate the relation between flexural deformation and the proof mass position. This study solved these problems by using a lead zirconate titanate (PZT) material, introducing additional electrodes for shielding, developing an optimal electrode pattern, and performing calibrations of undesired couplings. The results indicated that the fabricated device could be operated at 5.5±1 kHz to perform dual-axis actuations and position measurements. The calibration of the fabricated device was completed by system identifications of a new dynamic model including gyroscopic motions, electromechanical coupling, mechanical coupling, electrostatic coupling, and capacitive output impedance. Finally, without the assistance of control algorithms, the "open loop sensitivity" of the fabricated gyroscope was 1.82 μV/deg/s with a nonlinearity of 9.5% full-scale output. This sensitivity is comparable with those of other PZT gyroscopes with single-axis control inputs.
Design, Fabrication, and Modeling of a Novel Dual-Axis Control Input PZT Gyroscope
Directory of Open Access Journals (Sweden)
Cheng-Yang Chang
2017-10-01
Full Text Available Conventional gyroscopes are equipped with a single-axis control input, limiting their performance. Although researchers have proposed control algorithms with dual-axis control inputs to improve gyroscope performance, most have verified the control algorithms through numerical simulations because they lacked practical devices with dual-axis control inputs. The aim of this study was to design a piezoelectric gyroscope equipped with a dual-axis control input so that researchers may experimentally verify those control algorithms in future. Designing a piezoelectric gyroscope with a dual-axis control input is more difficult than designing a conventional gyroscope because the control input must be effective over a broad frequency range to compensate for imperfections, and the multiple mode shapes in flexural deformations complicate the relation between flexural deformation and the proof mass position. This study solved these problems by using a lead zirconate titanate (PZT material, introducing additional electrodes for shielding, developing an optimal electrode pattern, and performing calibrations of undesired couplings. The results indicated that the fabricated device could be operated at 5.5±1 kHz to perform dual-axis actuations and position measurements. The calibration of the fabricated device was completed by system identifications of a new dynamic model including gyroscopic motions, electromechanical coupling, mechanical coupling, electrostatic coupling, and capacitive output impedance. Finally, without the assistance of control algorithms, the “open loop sensitivity” of the fabricated gyroscope was 1.82 μV/deg/s with a nonlinearity of 9.5% full-scale output. This sensitivity is comparable with those of other PZT gyroscopes with single-axis control inputs.
Hemispherical Resonator Gyroscope Accuracy Analysis Under Temperature Influence
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Boran LI
2014-06-01
Full Text Available Frequency splitting of hemispherical resonator gyroscope will change as system operating temperature changes. This phenomenon leads to navigation accuracy of hemispherical resonator gyroscope reduces. By researching on hemispherical resonator gyroscope dynamical model and its frequency characteristic, the frequency splitting formula and the precession angle formula of gyroscope vibrating mode based on hemispherical resonator gyroscope dynamic equation parameters are derived. By comparison, gyroscope precession angle deviation caused by frequency splitting can be obtained. Based on analysis of temperature variation against gyroscope resonator, the design of hemispherical resonator gyroscope feedback controller under temperature variation conditions is researched and the maximum theoretical fluctuation of gyroscope dynamical is determined by using a numerical analysis example.
A novel differential frequency micro-gyroscope
Nayfeh, A. H.; Abdel-Rahman, E. M.; Ghommem, M.
2013-01-01
We present a frequency-domain method to measure angular speeds using electrostatic micro-electro-mechanical system actuators. Towards this end, we study a single-axis gyroscope made of a micro-cantilever and a proof-mass coupled to two fixed
Li, Li; Xu, Jian
Time delay is inevitable in unidirectionally coupled drive-free vibratory gyroscope system. The effect of time delay on the gyroscope system is studied in this paper. To this end, amplitude death and Hopf bifurcation induced by small time delay are first investigated by analyzing the related characteristic equation. Then, the direction of Hopf bifurcations and stability of Hopf-bifurcating periodic oscillations are determined by calculating the normal form on the center manifold. Next, spatiotemporal patterns of these Hopf-bifurcating periodic oscillations are analyzed by using the symmetric bifurcation theory of delay differential equations. Finally, it is found that numerical simulations agree with the associated analytic results. These phenomena could be induced although time delay is very small. Therefore, it is shown that time delay is an important factor which influences the sensitivity and accuracy of the gyroscope system and cannot be neglected during the design and manufacture.
Null result for violation of the equivalence principle with free-fall rotating gyroscopes
International Nuclear Information System (INIS)
Luo, J.; Zhou, Z.B.; Nie, Y.X.; Zhang, Y.Z.
2002-01-01
The differential acceleration between a rotating mechanical gyroscope and a nonrotating one is directly measured by using a double free-fall interferometer, and no apparent differential acceleration has been observed at the relative level of 2x10 -6 . It means that the equivalence principle is still valid for rotating extended bodies, i.e., the spin-gravity interaction between the extended bodies has not been observed at this level. Also, to the limit of our experimental sensitivity, there is no observed asymmetrical effect or antigravity of the rotating gyroscopes as reported by Hayasaka et al
Quantum gyroscope based on Berry phase of spins in diamond
Song, Xuerui; Wang, Liujun; Diao, Wenting; Duan, Chongdi
2018-02-01
Gyroscope is the crucial sensor of the inertial navigation system, there is always high demand to improve the sensitivity and reduce the size of the gyroscopes. Using the NV center electronic spin and nuclear spin qubits in diamond, we introduce the research of new types of quantum gyroscopes based on the Berry phase shifts of the spin states during the rotation of the sensor systems. Compared with the performance of the traditional MEMS gyroscope, the sensitivity of the new types of quantum gyroscopes was highly improved and the spatial resolution was reduced to nano-scale. With the help of micro-manufacturing technology in the semiconductor industry, the quantum gyroscopes introduced here can be further integrated into chip-scale sensors.
Optimization of the geometrical stability in square ring laser gyroscopes
International Nuclear Information System (INIS)
Santagata, R; Beghi, A; Cuccato, D; Belfi, J; Beverini, N; Virgilio, A Di; Ortolan, A; Porzio, A; Solimeno, S
2015-01-01
Ultra-sensitive ring laser gyroscopes are regarded as potential detectors of the general relativistic frame-dragging effect due to the rotation of the Earth. Our project for this goal is called GINGER (gyroscopes in general relativity), and consists of a ground-based triaxial array of ring lasers aimed at measuring the rotation rate of the Earth with an accuracy of 10 −14 rad s −1 . Such an ambitious goal is now within reach, as large-area ring lasers are very close to the required sensitivity and stability. However, demanding constraints on the geometrical stability of the optical path of the laser inside the ring cavity are required. Thus, we have begun a detailed study of the geometry of an optical cavity in order to find a control strategy for its geometry that could meet the specifications of the GINGER project. As the cavity perimeter has a stationary point for the square configuration, we identify a set of transformations on the mirror positions that allows us to adjust the laser beam steering to the shape of a square. We show that the geometrical stability of a square cavity strongly increases by implementing a suitable system to measure the mirror distances, and that the geometry stabilization can be achieved by measuring the absolute lengths of the two diagonals and the perimeter of the ring. (paper)
Scale factor measure method without turntable for angular rate gyroscope
Qi, Fangyi; Han, Xuefei; Yao, Yanqing; Xiong, Yuting; Huang, Yuqiong; Wang, Hua
2018-03-01
In this paper, a scale factor test method without turntable is originally designed for the angular rate gyroscope. A test system which consists of test device, data acquisition circuit and data processing software based on Labview platform is designed. Taking advantage of gyroscope's sensitivity of angular rate, a gyroscope with known scale factor, serves as a standard gyroscope. The standard gyroscope is installed on the test device together with a measured gyroscope. By shaking the test device around its edge which is parallel to the input axis of gyroscope, the scale factor of the measured gyroscope can be obtained in real time by the data processing software. This test method is fast. It helps test system miniaturized, easy to carry or move. Measure quarts MEMS gyroscope's scale factor multi-times by this method, the difference is less than 0.2%. Compare with testing by turntable, the scale factor difference is less than 1%. The accuracy and repeatability of the test system seems good.
The Anatomy of the Gyroscope. Part 3
1990-03-01
parts of the optical train by gyroscopic means; one of the first is that of JENSEN 1JS 2829557 (1958) who proposes a Porro - prism binocular telescope...to the ideas of JENSEN using Porro - prisms but we have neglected until now to refer to the work of KAESTNER who using porro - prisms and counterweights...CLEMENCE G.M. DYNAMICS OP THE SOLAR SYSTEM IBID pp. 2.60-2.68 ** See N.M.R. nuclear magnetic resonance , discovered 1945. ABRAGAM. A and GOLDMAN. M
Fiber optic gyroscopes for vehicle navigation systems
Kumagai, Tatsuya; Soekawa, Hirokazu; Yuhara, Toshiya; Kajioka, Hiroshi; Oho, Shigeru; Sonobe, Hisao
1994-03-01
Fiber optic gyroscopes (FOGs) have been developed for vehicle navigation systems and are used in Toyota Motor Corporation models Mark II, Chaser and Cresta in Japan. Use of FOGs in these systems requires high reliability under a wide range of conditions, especially in a temperature range between -40 and 85 degree(s)C. In addition, a high cost-performance ratio is needed. We have developed optical and electrical systems that are inexpensive and can perform well. They are ready to be mass-produced. FOGs have already been installed in luxury automobiles, and will soon be included in more basic vehicles. We have developed more inexpensive FOGs for this purpose.
Dynamics and control of vibratory gyroscopes with special spherical symmetry
CSIR Research Space (South Africa)
Shatalov, M
2006-01-01
Full Text Available It was shown in 1985 by Acad. V. Zhuravlev that the angular rate of a pure vibrating mode excited in a vibratory gyroscope with spherical symmetry is proportional to an inertial angular rate of the gyroscope. The effect is three dimensional...
Structure optimization and simulation analysis of the quartz micromachined gyroscope
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Xuezhong Wu
2014-02-01
Full Text Available Structure optimization and simulation analysis of the quartz micromachined gyroscope are reported in this paper. The relationships between the structure parameters and the frequencies of work mode were analysed by finite element analysis. The structure parameters of the quartz micromachined gyroscope were optimized to reduce the difference between the frequencies of the drive mode and the sense mode. The simulation results were proved by testing the prototype gyroscope, which was fabricated by micro-electromechanical systems (MEMS technology. Therefore, the frequencies of the drive mode and the sense mode can match each other by the structure optimization and simulation analysis of the quartz micromachined gyroscope, which is helpful in the design of the high sensitivity quartz micromachined gyroscope.
A novel differential frequency micro-gyroscope
Nayfeh, A. H.
2013-07-10
We present a frequency-domain method to measure angular speeds using electrostatic micro-electro-mechanical system actuators. Towards this end, we study a single-axis gyroscope made of a micro-cantilever and a proof-mass coupled to two fixed electrodes. The gyroscope possesses two orthogonal axes of symmetry and identical flexural mode shapes along these axes. We develop the equations of motion describing the coupled bending modes in the presence of electrostatic and Coriolis forces. Furthermore, we derive a consistent closed-form higher-order expression for the natural frequencies of the coupled flexural modes. The closed-form expression is verified by comparing its results to those obtained from numerical integration of the equations of motion. We find that rotations around the beam axis couple each pair of identical bending modes to produce a pair of global modes. They also split their common natural frequency into a pair of closely spaced natural frequencies. We propose the use of the difference between this pair of frequencies, which is linearly proportional to the speed of rotation around the beam axis, as a detector for the angular speed.
Fibre optic gyroscopes for space use
Faussot, Nicolas; Cottreau, Yann; Hardy, Guillaume; Simonpietri, Pascal; Gaiffe, Thierry
2017-11-01
Among the technologies available for gyroscopes usable in space, the Fibre Optic Gyroscope (FOG) technology appears to be the most suitable: no moving parts, very good lifetime, low power consumption, very low random walk, arbitrarily low angular resolution and very good behaviour in radiations and vacuum. Benefiting from more than ten years of experience with this technology, Ixsea (formerly the Navigation Division of Photonetics) is developing space FOG under both CNES and ESA contracts since many years. In the 1996-1998 period, two space FOG demonstrators in the 0,01°/h class were manufactured, including an optical head (optic and optoelectronic part) designed for space use and a standard ground electronics. Beyond the demonstration of the specified FOG performances, the behaviour of the optical head has been validated for use in typical space environment: vibrations, shocks, radiations (up to 50 krad) and thermal vacuum. Since the beginning of 1999, Ixsea is developing a space electronics in order to manufacture two complete space FOG. The first one entered in qualification in October. The second one will be delivered beginning of next year, it will be used in a CNES attitude measurement experiment (MAGI) onboard the FrenchBrazilian Microsatellite (FBM) partly dedicated to technology evaluation.
On the Interpretation of 3D Gyroscope Measurements
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Sara Stančin
2018-01-01
Full Text Available We demonstrate that the common interpretation of angular velocities measured by a 3D gyroscope as being sequential Euler rotations introduces a systematic error in the sensor orientation calculated during motion tracking. For small rotation angles, this systematic error is relatively small and can be mistakenly attributed to different sources of sensor inaccuracies, including output bias drift, inaccurate sensitivities, and alignments of the sensor sensitivity axes as well as measurement noise. However, even for such small angles, due to accumulation over time, the erroneous rotation interpretation can have a significant negative impact on the accuracy of the computed angular orientation. We confirm our findings using real-case measurements in which the described systematic error just worsens the deleterious effects typically attributed to an inaccurate sensor and random measurement noise. We demonstrate that, in general, significant improvement in the angular orientation accuracy can be achieved if the measured angular velocities are correctly interpreted as simultaneous and not as sequential rotations.
MEMS Gyroscopes Based on Acoustic Sagnac Effect
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Yuanyuan Yu
2016-12-01
Full Text Available This paper reports on the design, fabrication and preliminary test results of a novel microelectromechanical systems (MEMS device—the acoustic gyroscope. The unique operating mechanism is based on the “acoustic version” of the Sagnac effect in fiber-optic gyros. The device measures the phase difference between two sound waves traveling in opposite directions, and correlates the signal to the angular velocity of the hosting frame. As sound travels significantly slower than light and develops a larger phase change within the same path length, the acoustic gyro can potentially outperform fiber-optic gyros in sensitivity and form factor. It also promises superior stability compared to vibratory MEMS gyros as the design contains no moving parts and is largely insensitive to mechanical stress or temperature. We have carried out systematic simulations and experiments, and developed a series of processes and design rules to implement the device.
Solid-state ring laser gyroscope
Schwartz, S.
The ring laser gyroscope is a rotation sensor used in most kinds of inertial navigation units. It usually consists in a ring cavity filled with a mixture of helium and neon, together with high-voltage pumping electrodes. The use of a gaseous gain medium, while resulting naturally in a stable bidirectional regime enabling rotation sensing, is however the main industrially limiting factor for the ring laser gyroscopes in terms of cost, reliability and lifetime. We study in this book the possibility of substituting for the gaseous gain medium a solid-state medium (diode-pumped Nd-YAG). For this, a theoretical and experimental overview of the lasing regimes of the solid-state ring laser is reported. We show that the bidirectional emission can be obtained thanks to a feedback loop acting on the states of polarization and inducing differential losses proportional to the difference of intensity between the counterpropagating modes. This leads to the achievement of a solid-state ring laser gyroscope, whose frequency response is modified by mode coupling effects. Several configurations, either mechanically or optically based, are then successively studied, with a view to improving the quality of this frequency response. In particular, vibration of the gain crystal along the longitudinal axis appears to be a very promising technique for reaching high inertial performances with a solid-state ring laser gyroscope. Gyrolaser à état solide. Le gyrolaser est un capteur de rotation utilisé dans la plupart des centrales de navigation inertielle. Dans sa forme usuelle, il est constitué d'une cavité laser en anneau remplie d'un mélange d'hélium et de néon pompé par des électrodes à haute tension. L'utilisation d'un milieu amplificateur gazeux, si elle permet de garantir naturellement le fonctionnement bidirectionnel stable nécessaire à la mesure des rotations, constitue en revanche la principale limitation industrielle des gyrolasers actuels en termes de coût, fiabilit
Videometrics-based Detection of Vibration Linearity in MEMS Gyroscope
Directory of Open Access Journals (Sweden)
Yong Zhou
2011-05-01
Full Text Available MEMS gyroscope performs as a sort of sensor to detect angular velocity, with diverse applications in engineering including vehicle and intelligent traffic etc. A balanced vibration of driving module excited by electrostatic driving signal is the base MEMS gyroscope's performance. In order to analyze the linear property of vibration in MEMS Gyroscope, a method of computer vision measuring is applied with the help of high-speed vidicon to obtain video of linear vibration of driving module in gyroscope, under the driving voltage signal of inherent frequency and amplitude linearly increasing. By means of image processing, target identifying, and motion parameter extracting from the obtained video, vibration curve with time variation is acquired. And then, linearity of this vibration system can be analyzed by focusing on the amplitude value of vibration responding to the amplitude variation of driving voltage signal.
Vibratory gyroscopes : identification of mathematical model from test data
CSIR Research Space (South Africa)
Shatalov, MY
2007-05-01
Full Text Available Simple mathematical model of vibratory gyroscopes imperfections is formulated, which includes anisotropic damping and variation of mass-stiffness parameters and their harmonics. The method of identification of parameters of the mathematical model...
Fast-light Enhanced Fiber Gyroscope, Phase I
National Aeronautics and Space Administration — Current state-of-the-art navigation systems incorporate optical gyroscopes and optical accelerometers as inertial sensors. These devices contain no moving parts and...
Resonant microsphere gyroscope based on a double Faraday rotator system.
Xie, Chengfeng; Tang, Jun; Cui, Danfeng; Wu, Dajin; Zhang, Chengfei; Li, Chunming; Zhen, Yongqiu; Xue, Chenyang; Liu, Jun
2016-10-15
The resonant microsphere gyroscope is proposed based on a double Faraday rotator system for the resonant microsphere gyroscope (RMSG) that is characterized by low insertion losses and does not destroy the reciprocity of the gyroscope system. Use of the echo suppression structure and the orthogonal polarization method can effectively inhibit both the backscattering noise and the polarization error, and reduce them below the system sensitivity limit. The resonance asymmetry rate dropped from 34.2% to 2.9% after optimization of the backscattering noise and the polarization noise, which greatly improved the bias stability and the scale factor linearity of the proposed system. Additionally, based on the optimum parameters for the double Faraday rotator system, a bias stability of 0.04°/s has been established for an integration time of 10 s in 1000 s in a resonator microsphere gyroscope using a microsphere resonator with a diameter of 1 mm and a Q of 7.2×106.
Buret, Thomas; Ramecourt, David; Napolitano, Fabien
2017-11-01
The aim of this article is to present how the qualification of the Fiber Optic Gyroscope technology from IXSEA has been achieved through the qualification of a large range of optical devices and related manufacturing processes. These qualified optical devices and processes, that are now fully mastered by IXSEA through vertical integration of the technology, can be used for other space optical sensors. The example of the SWARM project will be discussed.
Development of thin film encapsulation process for piezoresistive MEMS gyroscope with wide gaps
Ayanoor-Vitikkate, Vipin
The gyroscope is an inertial sensor used to measure the angular rate of a rotating object. This helps to determine the pitch and yaw rate of any moving body. A number of applications have been developed for consumer and automotive markets, for e.g. vehicle stability control, navigation assist, roll over detection. These are primarily used in high-end cars, where cost is not a major factor. Other areas where a MEMS Gyro can be used are robotics, camcorder stabilization, virtual reality, and more. Primarily due to cost and the size most of these applications have not reached any significant volume. One reason for this is the relatively high cost of MEMS gyros compared to other MEMS sensors like accelerometers or pressure sensors. Generally the cost of packaging a MEMS sensor is about 85-90% of the total cost. Currently most MEMS based gyroscopes are made using bulk or surface micromachining, after which they are packaged using wafer bonding. This unfortunately leads to wastage of silicon and increase in the package size, thus reducing the yield. One way to reduce the cost of packaging is by wafer scale thin film encapsulation of MEMS gyroscopes. The goal of the present work is to fabricate a rate grade MEMS gyroscope and encapsulate it by modifying an existing thin-film encapsulation technique. Packaging is an important step towards commercialization of the device and we plan to use thin wafer scale encapsulation technique developed previously in our group to package these devices. The silicon micro machined gyroscope will be fabricated on SOI (Silicon-on-Insulator) wafers using Bosch DRIE etching techniques. The encapsulation of the device is carried out using epitaxial polysilicon in order to provide a high vacuum inside the device chamber. The advantages offered by this technique are the reduction in area of the die and thus less silicon surface is wasted. In addition to this the encapsulation technique helps in creating a vacuum inside the micro device, which
Reproducibility of a 3-dimensional gyroscope in measuring shoulder anteflexion and abduction
Directory of Open Access Journals (Sweden)
Penning Ludo I F
2012-07-01
Full Text Available Abstract Background Few studies have investigated the use of a 3-dimensional gyroscope for measuring the range of motion (ROM in the impaired shoulder. Reproducibility of digital inclinometer and visual estimation is poor. This study aims to investigate the reproducibility of a tri axial gyroscope in measurement of anteflexion, abduction and related rotations in the impaired shoulder. Methods Fifty-eight patients with either subacromial impingement (27 or osteoarthritis of the shoulder (31 participated. Active anteflexion, abduction and related rotations were measured with a tri axial gyroscope according to a test retest protocol. Severity of shoulder impairment and patient perceived pain were assessed by the Disability of Arm Shoulder and Hand score (DASH and the Visual Analogue Scale (VAS. VAS scores were recorded before and after testing. Results In two out of three hospitals patients with osteoarthritis (n = 31 were measured, in the third hospital patients with subacromial impingement (n = 27. There were significant differences among hospitals for the VAS and DASH scores measured before and after testing. The mean differences between the test and retest means for anteflexion were −6 degrees (affected side, 9 (contralateral side and for abduction 15 degrees (affected side and 10 degrees (contralateral side. Bland & Altman plots showed that the confidence intervals for the mean differences fall within −6 up to 15 degrees, individual test - retest differences could exceed these limits. A simulation according to ‘Generalizability Theory’ produces very good coefficients for anteflexion and related rotation as a comprehensive measure of reproducibility. Optimal reproducibility is achieved with 2 repetitions for anteflexion. Conclusions Measurements were influenced by patient perceived pain. Differences in VAS and DASH might be explained by different underlying pathology. These differences in shoulder pathology however did not alter
Directory of Open Access Journals (Sweden)
Jiaying Du
2018-04-01
Full Text Available Motion sensors such as MEMS gyroscopes and accelerometers are characterized by a small size, light weight, high sensitivity, and low cost. They are used in an increasing number of applications. However, they are easily influenced by environmental effects such as temperature change, shock, and vibration. Thus, signal processing is essential for minimizing errors and improving signal quality and system stability. The aim of this work is to investigate and present a systematic review of different signal error reduction algorithms that are used for MEMS gyroscope-based motion analysis systems for human motion analysis or have the potential to be used in this area. A systematic search was performed with the search engines/databases of the ACM Digital Library, IEEE Xplore, PubMed, and Scopus. Sixteen papers that focus on MEMS gyroscope-related signal processing and were published in journals or conference proceedings in the past 10 years were found and fully reviewed. Seventeen algorithms were categorized into four main groups: Kalman-filter-based algorithms, adaptive-based algorithms, simple filter algorithms, and compensation-based algorithms. The algorithms were analyzed and presented along with their characteristics such as advantages, disadvantages, and time limitations. A user guide to the most suitable signal processing algorithms within this area is presented.
Du, Jiaying; Gerdtman, Christer; Lindén, Maria
2018-04-06
Motion sensors such as MEMS gyroscopes and accelerometers are characterized by a small size, light weight, high sensitivity, and low cost. They are used in an increasing number of applications. However, they are easily influenced by environmental effects such as temperature change, shock, and vibration. Thus, signal processing is essential for minimizing errors and improving signal quality and system stability. The aim of this work is to investigate and present a systematic review of different signal error reduction algorithms that are used for MEMS gyroscope-based motion analysis systems for human motion analysis or have the potential to be used in this area. A systematic search was performed with the search engines/databases of the ACM Digital Library, IEEE Xplore, PubMed, and Scopus. Sixteen papers that focus on MEMS gyroscope-related signal processing and were published in journals or conference proceedings in the past 10 years were found and fully reviewed. Seventeen algorithms were categorized into four main groups: Kalman-filter-based algorithms, adaptive-based algorithms, simple filter algorithms, and compensation-based algorithms. The algorithms were analyzed and presented along with their characteristics such as advantages, disadvantages, and time limitations. A user guide to the most suitable signal processing algorithms within this area is presented.
Modeling and optimizing of the random atomic spin gyroscope drift based on the atomic spin gyroscope
Energy Technology Data Exchange (ETDEWEB)
Quan, Wei; Lv, Lin, E-mail: lvlinlch1990@163.com; Liu, Baiqi [School of Instrument Science and Opto-Electronics Engineering, Beihang University, Beijing 100191 (China)
2014-11-15
In order to improve the atom spin gyroscope's operational accuracy and compensate the random error caused by the nonlinear and weak-stability characteristic of the random atomic spin gyroscope (ASG) drift, the hybrid random drift error model based on autoregressive (AR) and genetic programming (GP) + genetic algorithm (GA) technique is established. The time series of random ASG drift is taken as the study object. The time series of random ASG drift is acquired by analyzing and preprocessing the measured data of ASG. The linear section model is established based on AR technique. After that, the nonlinear section model is built based on GP technique and GA is used to optimize the coefficients of the mathematic expression acquired by GP in order to obtain a more accurate model. The simulation result indicates that this hybrid model can effectively reflect the characteristics of the ASG's random drift. The square error of the ASG's random drift is reduced by 92.40%. Comparing with the AR technique and the GP + GA technique, the random drift is reduced by 9.34% and 5.06%, respectively. The hybrid modeling method can effectively compensate the ASG's random drift and improve the stability of the system.
Magnetometer and Gyroscope Calibration Method with Level Rotation
Directory of Open Access Journals (Sweden)
Zongkai Wu
2018-03-01
Full Text Available Micro electro mechanical system (MEMS gyroscopes and magnetometers are usually integrated into a sensor module or chip and widely used in a variety of applications. In existing integrated gyroscope and magnetometer calibration methods, rotation in all possible orientations is a necessary condition for a good calibration result. However, rotation around two or more axes is difficult to attain, as it is limited by the range of movement of vehicles such as cars, ships, or planes. To solve this problem, this paper proposes an integrated magnetometer and gyroscope calibration method with level rotation. The proposed method presents a redefined magnetometer output model using level attitude. New gyroscope and magnetometer calibration models are then deduced. In addition, a simplified cubature Kalman filter (CKF is established to estimate calibration parameters. This method possesses important value for application in actual systems, as it only needs level rotation for real-time calibration of gyroscopes and magnetometers. Theoretical analysis and test results verify the validity and feasibility of this method.
Compact fiber optic gyroscopes for platform stabilization
Dickson, William C.; Yee, Ting K.; Coward, James F.; McClaren, Andrew; Pechner, David A.
2013-09-01
SA Photonics has developed a family of compact Fiber Optic Gyroscopes (FOGs) for platform stabilization applications. The use of short fiber coils enables the high update rates required for stabilization applications but presents challenges to maintain high performance. We are able to match the performance of much larger FOGs by utilizing several innovative technologies. These technologies include source noise reduction to minimize Angular Random Walk (ARW), advanced digital signal processing that minimizes bias drift at high update rates, and advanced passive thermal packaging that minimizes temperature induced bias drift while not significantly affecting size, weight, or power. In addition, SA Photonics has developed unique distributed FOG packaging technologies allowing the FOG electronics and photonics to be packaged remotely from the sensor head or independent axis heads to minimize size, weight, and power at the sensing location(s). The use of these technologies has resulted in high performance, including ARW less than 0.001 deg/rt-hr and bias drift less than 0.004 deg/hr at an update rate of 10 kHz, and total packaged volume less than 30 cu. in. for a 6 degree of freedom FOG-based IMU. Specific applications include optical beam stabilization for LIDAR and LADAR, beam stabilization for long-range free-space optical communication, Optical Inertial Reference Units for HEL stabilization, and Ka band antenna pedestal pointing and stabilization. The high performance of our FOGs also enables their use in traditional navigation and positioning applications. This paper will review the technologies enabling our high-performance compact FOGs, and will provide performance test results.
ATMOSPHERE PRESSURE EFFECT ON THE FIBER OPTIC GYROSCOPE OUTPUT SYGNAL
Directory of Open Access Journals (Sweden)
Ilya A. Sharkov
2017-05-01
Full Text Available The paper describes research results of the atmospheric pressure effect on the output signal of a fiber optic gyroscope (FOG. In the course of experiments, FOG was placed into a hermetic chamber. The atmosphere pressure was varying in the range from 0.8 to 1.5 atm. All the data, including the FOG output signal, temperature, and data from the pressure sensor installed inside the FOG, were synchronously registered with the computer software. The separation of scale factor change from zero offset in the experiment was carried out by setting the sensitive FOG axis at 0°, 90° and 270° relative to the East (the FOG was set perpendicular to the horizon. After the data processing it was concluded that the FOG signal error associated with the pressure affects mainly on the additive component. The pressure effect on the multiplicative component appeared to be negligible at rotational velocities used in the experiment (0 - 130 /h. At the same time, the FOG signal has a high linear correlation coefficient with the derivative of pressure over time (in some cases, more than 0.9. The experiment was repeated several times and the high degree of the drift repeatability was shown. That makes it possible to implement the compensation algorithm. Application of the simplest algorithmic compensation based on the polynomial of the first degree (ax + b enabled to reduce the root-mean-square (RMS and drift of the signal by 2-9 times.
Yang, Xiao-Dong; An, Hua-Zhen; Qian, Ying-Jing; Zhang, Wei; Melnik, Roderick V. N.
2016-12-01
The synchronous in-unison motions in vibrational mechanics and the non-synchronous out-of-unison motions are the most frequently found periodic motions in every fields of science and everywhere in the universe. In contrast to the in-unison normal modes, the out-of-unison complex modes feature a π/2 phase difference. By the complex mode analysis we classify the out-of-unison planar motion into two types, gyroscopic motions and elliptic motions. It is found that the gyroscopic and elliptic motions have different characteristics for a two degree-of-freedom (2DOF) system. The gyroscopic motion involves two distinct frequencies with, respectively, two corresponding complex modes. However, the elliptic motion the nonlinear non-gyroscopic 2DOF system with repeated frequencies involves only single frequency with corresponding two complex modes. The study of the differences and similarities of the gyroscopic and elliptic modes sheds new light on the in-depth mechanism of the planar motions in the universe and the man-made engineering systems.
Thermal and Quantum Mechanical Noise of a Superfluid Gyroscope
Chui, Talso; Penanen, Konstantin
2004-01-01
A potential application of a superfluid gyroscope is for real-time measurements of the small variations in the rotational speed of the Earth, the Moon, and Mars. Such rotational jitter, if not measured and corrected for, will be a limiting factor on the resolution potential of a GPS system. This limitation will prevent many automation concepts in navigation, construction, and biomedical examination from being realized. We present the calculation of thermal and quantum-mechanical phase noise across the Josephson junction of a superfluid gyroscope. This allows us to derive the fundamental limits on the performance of a superfluid gyroscope. We show that the fundamental limit on real-time GPS due to rotational jitter can be reduced to well below 1 millimeter/day. Other limitations and their potential mitigation will also be discussed.
Microfibrous metallic cloth for acoustic isolation of a MEMS gyroscope
Dean, Robert; Burch, Nesha; Black, Meagan; Beal, Aubrey; Flowers, George
2011-04-01
The response of a MEMS device that is exposed to a harsh environment may range from an increased noise floor to a completely erroneous output to temporary or even permanent device failure. One such harsh environment is high power acoustic energy possessing high frequency components. This type of environment sometimes occurs in small aerospace vehicles. In this type of operating environment, high frequency acoustic energy can be transferred to a MEMS gyroscope die through the device packaging. If the acoustic noise possesses a sufficiently strong component at the resonant frequency of the gyroscope, it will overexcite the motion of the proof mass, resulting in the deleterious effect of corrupted angular rate measurement. Therefore if the device or system packaging can be improved to sufficiently isolate the gyroscope die from environmental acoustic energy, the sensor may find new applications in this type of harsh environment. This research effort explored the use of microfibrous metallic cloth for isolating the gyroscope die from environmental acoustic excitation. Microfibrous cloth is a composite of fused, intermingled metal fibers and has a variety of typical uses involving chemical processing applications and filtering. Specifically, this research consisted of experimental evaluations of multiple layers of packed microfibrous cloth composed of sintered nickel material. The packed cloth was used to provide acoustic isolation for a test MEMS gyroscope, the Analog Devices ADXRS300. The results of this investigation revealed that the intermingling of the various fibers of the metallic cloth provided a significant contact area between the fiber strands and voids, which enhanced the acoustic damping of the material. As a result, the nickel cloth was discovered to be an effective acoustic isolation material for this particular MEMS gyroscope.
Studying rotational dynamics with a smartphone—accelerometer versus gyroscope
Braskén, Mats; Pörn, Ray
2017-07-01
The wide-spread availability of smartphones makes them a valuable addition to the measurement equipment of both the physics classroom and the instructional physics laboratory, encouraging an active interaction between measurements and modeling activities. Two useful sensors, available in most modern smartphones and tablets, are the 3-axis acceleration sensor and the 3-axis gyroscope. We explore the strengths and weaknesses of each type of sensor and use them to study the rotational dynamics of objects rotating about a fixed axis. Care has to be taken when interpreting acceleration sensor data, and in some cases the gyroscope will allow for rotational measurements not easily replicated using the acceleration sensor.
Construction of Lyapunov Function for Dissipative Gyroscopic System
International Nuclear Information System (INIS)
Xu Wei; Ao Ping; Yuan Bo
2011-01-01
We introduce a force decomposition to construct a potential function in deterministic dynamics described by ordinary differential equations in the context of dissipative gyroscopic systems. Such a potential function serves as the corresponding Lyapunov function for the dynamics, hence it gives both quantitative and qualitative descriptions for stability of motion. As an example we apply our force decomposition to a four-dimensional dissipative gyroscopic system. We explicitly obtain the potential function for all parameter regimes in the linear limit, including those regimes where the Lyapunov function was previously believed not to exist. (general)
Isolated resonator gyroscope with a drive and sense plate
Challoner, A. Dorian (Inventor); Shcheglov, Kirill V. (Inventor)
2006-01-01
The present invention discloses a resonator gyroscope comprising a vibrationally isolated resonator including a proof mass, a counterbalancing plate having an extensive planar region, and one or more flexures interconnecting the proof mass and counterbalancing plate. A baseplate is affixed to the resonator by the one or more flexures and sense and drive electrodes are affixed to the baseplate proximate to the extensive planar region of the counterbalancing plate for exciting the resonator and sensing movement of the gyroscope. The isolated resonator transfers substantially no net momentum to the baseplate when the resonator is excited.
Zhang, Hao; Li, Wenxiu; Han, Peng; Chang, Xiaoyang; Liu, Jiaming; Lin, Jian; Xue, Xia; Zhu, Fang; Yang, Yang; Liu, Xiaojing; Zhang, Xiaofu; Huang, Anping; Xiao, Zhisong; Fang, Jiancheng
2018-01-01
Anomalous dispersion enhancement physical mechanism for Sagnac effect is described by special relativity derivation, and three kinds of definitions of minimum detectable angular rate of resonance optical gyroscope (ROG) are compared and the relations among them are investigated. The effect of linewidth broadening induced by anomalous dispersion on the sensitivity of ROG is discussed in this paper. Material dispersion-broadened resonance linewidth deteriorates the performance of a passive ROG and dispersion enhancement effect, while the sensitivity of a structural dispersion ROG is enhanced by two orders of magnitude even considering the dispersion-broadened resonance linewidth.
Coupled electromechanical model of an imperfect piezoelectric vibrating cylinder gyroscope
CSIR Research Space (South Africa)
Loveday, PW
1996-01-01
Full Text Available which is closed at one end with discrete piezoceramic actuation and sensing elements bonded close to the open end. The operation of the gyroscope and the effect of imperfections are briefly described. The model allows direct comparison with experimental...
General problems of dynamics and control of vibratory gyroscopes
CSIR Research Space (South Africa)
Shatalov, MY
2008-05-01
Full Text Available A general model of operation of vibratory gyroscopes, which is applicable to a broad class of instruments, including cylindrical, disc and micro-machined gyros, is formulated on the basis of analysis of dynamics and control of a hemispherical...
FPGA platform for MEMS Disc Resonance Gyroscope (DRG) control
Keymeulen, Didier; Peay, Chris; Foor, David; Trung, Tran; Bakhshi, Alireza; Withington, Phil; Yee, Karl; Terrile, Rich
2008-04-01
Inertial navigation systems based upon optical gyroscopes tend to be expensive, large, power consumptive, and are not long lived. Micro-Electromechanical Systems (MEMS) based gyros do not have these shortcomings; however, until recently, the performance of MEMS based gyros had been below navigation grade. Boeing and JPL have been cooperating since 1997 to develop high performance MEMS gyroscopes for miniature, low power space Inertial Reference Unit applications. The efforts resulted in demonstration of a Post Resonator Gyroscope (PRG). This experience led to the more compact Disc Resonator Gyroscope (DRG) for further reduced size and power with potentially increased performance. Currently, the mass, volume and power of the DRG are dominated by the size of the electronics. This paper will detail the FPGA based digital electronics architecture and its implementation for the DRG which will allow reduction of size and power and will increase performance through a reduction in electronics noise. Using the digital control based on FPGA, we can program and modify in real-time the control loop to adapt to the specificity of each particular gyro and the change of the mechanical characteristic of the gyro during its life time.
Understanding Organizational Culture and Communication through a Gyroscope Metaphor
Bisel, Ryan S.; Messersmith, Amber S.; Keyton, Joann
2010-01-01
To fill a critical void in organizational culture pedagogy, the authors present an instructional system that employs the metaphor of a gyroscope to help students understand implicit assumptions in culture research. Working from Martin's nexus approach to organizational culture and Fairhurst and Putnam's tripartite theory of organizational…
Molecular gyroscopes and biological effects of weak extremely low-frequency magnetic fields
International Nuclear Information System (INIS)
Binhi, V.N.; Savin, A.V.
2002-01-01
Extremely low-frequency magnetic fields are known to affect biological systems. In many cases, biological effects display 'windows' in biologically effective parameters of the magnetic fields: most dramatic is the fact that the relatively intense magnetic fields sometimes do not cause appreciable effect, while smaller fields of the order of 10-100 μT do. Linear resonant physical processes do not explain the frequency windows in this case. Amplitude window phenomena suggest a nonlinear physical mechanism. Such a nonlinear mechanism has been proposed recently to explain those 'windows'. It considers the quantum-interference effects on the protein-bound substrate ions. Magnetic fields cause an interference of ion quantum states and change the probability of ion-protein dissociation. This ion-interference mechanism predicts specific magnetic-field frequency and amplitude windows within which the biological effects occur. It agrees with a lot of experiments. However, according to the mechanism, the lifetime Γ -1 of ion quantum states within a protein cavity should be of unrealistic value, more than 0.01 s for frequency band 10-100 Hz. In this paper, a biophysical mechanism has been proposed, which (i) retains the attractive features of the ion interference mechanism, i.e., predicts physical characteristics that might be experimentally examined and (ii) uses the principles of gyroscopic motion and removes the necessity to postulate large lifetimes. The mechanism considers the dynamics of the density matrix of the molecular groups, which are attached to the walls of protein cavities by two covalent bonds, i.e., molecular gyroscopes. Numerical computations have shown almost free rotations of the molecular gyroscopes. The relaxation time due to van der Waals forces was about 0.01 s for the cavity size of 28 Aa
SCALE FACTOR DETERMINATION METHOD OF ELECTRO-OPTICAL MODULATOR IN FIBER-OPTIC GYROSCOPE
Directory of Open Access Journals (Sweden)
A. S. Aleynik
2016-05-01
Full Text Available Subject of Research. We propose a method for dynamic measurement of half-wave voltage of electro-optic modulator as part of a fiber optic gyroscope. Excluding the impact of the angular acceleration on measurement of the electro-optical coefficient is achieved through the use of homodyne demodulation method that allows a division of the Sagnac phase shift signal and an auxiliary signal for measuring the electro-optical coefficient in the frequency domain. Method. The method essence reduces to decomposition of step of digital serrodyne modulation in two parts with equal duration. The first part is used for quadrature modulation signals. The second part comprises samples of the auxiliary signal used to determine the value of the scale factor of the modulator. Modeling is done in standalone model, and as part of a general model of the gyroscope. The applicability of the proposed method is investigated as well as its qualitative and quantitative characteristics: absolute and relative accuracy of the electro-optic coefficient, the stability of the method to the effects of angular velocities and accelerations, method resistance to noise in actual devices. Main Results. The simulation has showed the ability to measure angular velocity changing under the influence of angular acceleration, acting on the device, and simultaneous measurement of electro-optical coefficient of the phase modulator without interference between these processes. Practical Relevance. Featured in the paper the ability to eliminate the influence of the angular acceleration on the measurement accuracy of the electro-optical coefficient of the phase modulator will allow implementing accurate measurement algorithms for fiber optic gyroscopes resistant to a significant acceleration in real devices.
Fibre Optic Gyroscope Developments Using Integrated Optic Components
Minford, W. J.; DePaula, R. M.
1988-09-01
The sensing of rotation using counterpropagating optical beams in a fiber loop (the SAGNAC effect) has gone through extensive developments and demonstrations since first proved feasible by Vali and Shorthilll in 1976. The interferometric fiber gyroscope minimum configuration2 which uses a common input-output port and single-mode filter was developed to provide the extreme high stability necessary to reach the sensitivities at low rotation rates attainable with current state-of-the-art detectors. The simplicity and performance of this configuration has led to its acceptance and wide-spread use. In order to increase the mechanical stability of this system, all single-mode fiber components are employed and a further advancement to integrated optics has enabled most of the optical functions to be placed on a single mass-producible substrate. Recent improvements in the components (eg polarization maintaining fiber and low coherence sources) have further enhanced the performance of the minimum configuration gyro. This presentation focused on the impact of LiNbO3 integrated optic components on gyroscope developments. The use of Ti-indiffused LiNbO3 waveguide optical circuits in interferometric fiber optic gyroscopes has taken two directions: to utilize only the phase modulator, or to combine many of the minimum configuration optical functions on the electro-optic substrate. The high-bandwidth phase modulator is the driving force for using LiNbO3 waveguide devices. This device allows both biasing the gyro for maximum sensitivity and closing the loop via frequency shifting, for example, thus increasing the dynamic range of the gyro and the linearity of the scale factor. Efforts to implement most of the minimum configuration optical functions onto a single LiNbO3 substrate have been led by Thomson CSF.3 They have demonstrated an interferometric gyroscope with excellent performance using a LiNbO3 optical circuit containing a Y-splitter, phase modulator, and surface
A Fully Symmetric and Completely Decoupled MEMS-SOI Gyroscope
Directory of Open Access Journals (Sweden)
Abdelhameed SHARAF
2011-04-01
Full Text Available This paper introduces a novel MEMS gyroscope that is capable of exciting the drive mode differentially. The structure also decouples the drive and sense modes via an intermediate mass and decoupling beams. Both drive and sense modes are fully differential enabling control over the zero-rate-output for the former and maximizing output sensitivity using a bridge circuit for the latter. Further, the structure is fully symmetric about the x- and y- axes which results in minimizing the temperature sensitivity problem. Complete analytical analysis based on the equations of motion was performed and verified using two commercially available finite element software packages. Results from both methods are in good agreement. The analysis of the sensor shows an electrical sensitivity of 1.14 (mV/(º/s. The gyroscope was fabricated using single mask and deep reactive ion etching. The measurement of the resonance frequency performed showing a good agreement with the analytical and numerical analysis.
Collision avoidance for multiple Lagrangian dynamical systems with gyroscopic forces
Directory of Open Access Journals (Sweden)
Lorenzo Sabattini
2017-01-01
Full Text Available This article introduces a novel methodology for dealing with collision avoidance for groups of mobile robots. In particular, full dynamics are considered, since each robot is modeled as a Lagrangian dynamical system moving in a three-dimensional environment. Gyroscopic forces are utilized for defining the collision avoidance control strategy: This kind of forces leads to avoiding collisions, without interfering with the convergence properties of the multi-robot system’s desired control law. Collision avoidance introduces, in fact, a perturbation on the nominal behavior of the system: We define a method for choosing the direction of the gyroscopic force in an optimal manner, in such a way that perturbation is minimized. Collision avoidance and convergence properties are analytically demonstrated, and simulation results are provided for validation purpose.
Servo Platform Circuit Design of Pendulous Gyroscope Based on DSP
Tan, Lilong; Wang, Pengcheng; Zhong, Qiyuan; Zhang, Cui; Liu, Yunfei
2018-03-01
In order to solve the problem when a certain type of pendulous gyroscope in the initial installation deviation more than 40 degrees, that the servo platform can not be up to the speed of the gyroscope in the rough north seeking phase. This paper takes the digital signal processor TMS320F28027 as the core, uses incremental digital PID algorithm, carries out the circuit design of the servo platform. Firstly, the hardware circuit is divided into three parts: DSP minimum system, motor driving circuit and signal processing circuit, then the mathematical model of incremental digital PID algorithm is established, based on the model, writes the PID control program in CCS3.3, finally, the servo motor tracking control experiment is carried out, it shows that the design can significantly improve the tracking ability of the servo platform, and the design has good engineering practice.
Characterization and Modeling of a Control Moment Gyroscope
2015-03-26
pre- conditioner for the input state before passing into the inner loop, as shown in Figure 30. In Figure 30, m is the motor angle and x is the state...Characterization and Modeling of a Control Moment Gyroscope THESIS 2d Lt, Dylan Penn, B.S. AFIT-ENY-MS-15-M-235 DEPARTMENT OF THE AIR FORCE AIR ...UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio DISTRIBUTION STATEMENT A APPROVED FOR PUBLIC RELEASE; DISTRIBUTION
OPTIMIZATION OF HEMISPHERICAL RESONATOR GYROSCOPE STANDING WAVE PARAMETERS
Directory of Open Access Journals (Sweden)
Olga Sergeevna Khalyutina
2017-01-01
Full Text Available Traditionally, the problem of autonomous navigation is solved by dead reckoning navigation flight parameters (NFP of the aircraft (AC. With increasing requirements to accuracy of definition NFP improved the sensors of the prima- ry navigation information: gyroscopes and accelerometers. the gyroscopes of a new type, the so-called solid-state wave gyroscopes (SSVG are currently developed and put into practice. The work deals with the problem of increasing the accu- racy of measurements of angular velocity of the hemispherical resonator gyroscope (HRG. The reduction in the accuracy characteristics of HRG is caused by the presence of defects in the distribution of mass in the volume of its design. The syn- thesis of control system for optimal damping of the distortion parameters of the standing wave due to the influence of the mass defect resonator is adapted. The research challenge was: to examine and analytically offset the impact of the standing wave (amplitude and frequency parameters defect. Research was performed by mathematical modeling in the environment of SolidWorks Simulation for the case when the characteristics of the sensitive element of the HRG met the technological drawings of a particular type of resonator. The method of the inverse dynamics was chosen for synthesis. The research re- sults are presented in graphs the amplitude-frequency characteristics (AFC of the resonator output signal. Simulation was performed for the cases: the perfect distribution of weight; the presence of the mass defect; the presence of the mass defects are shown using the synthesized control action. Evaluating the effectiveness of the proposed control algorithm is deter- mined by the results of the resonator output signal simulation provided the perfect constructive and its performance in the presence of a mass defect in it. It is assumed that the excitation signals are standing waves in the two cases are identical in both amplitude and frequency. In this
The Gyroscope Sensor Test by Using Arduino Platform
Directory of Open Access Journals (Sweden)
Yi-Jen Mon
2015-06-01
Full Text Available Abstract The gyroscope has ability to get accurate data of motions for space of three dimensions such as axes of x y and z. Its applications are covered very widely such as in mobile phone consumer electronics etc. due to the robust sense abilities of direction and motion. In this paper it is used to get data from motion and these data are shown in window and LCD screen. The experiment results show that it has good performance.
Nitzan, Sarah H; Zega, Valentina; Li, Mo; Ahn, Chae H; Corigliano, Alberto; Kenny, Thomas W; Horsley, David A
2015-03-12
Parametric amplification, resulting from intentionally varying a parameter in a resonator at twice its resonant frequency, has been successfully employed to increase the sensitivity of many micro- and nano-scale sensors. Here, we introduce the concept of self-induced parametric amplification, which arises naturally from nonlinear elastic coupling between the degenerate vibration modes in a micromechanical disk-resonator, and is not externally applied. The device functions as a gyroscope wherein angular rotation is detected from Coriolis coupling of elastic vibration energy from a driven vibration mode into a second degenerate sensing mode. While nonlinear elasticity in silicon resonators is extremely weak, in this high quality-factor device, ppm-level nonlinear elastic effects result in an order-of-magnitude increase in the observed sensitivity to Coriolis force relative to linear theory. Perfect degeneracy of the primary and secondary vibration modes is achieved through electrostatic frequency tuning, which also enables the phase and frequency of the parametric coupling to be varied, and we show that the resulting phase and frequency dependence of the amplification follow the theory of parametric resonance. We expect that this phenomenon will be useful for both fundamental studies of dynamic systems with low dissipation and for increasing signal-to-noise ratio in practical applications such as gyroscopes.
Lu, Haohui; Chai, Tan; Cooley, Christopher G.
2018-03-01
This study investigates the vibration of a rotating piezoelectric device that consists of a proof mass that is supported by elastic structures with piezoelectric layers. Vibration of the proof mass causes deformation in the piezoelectric structures and voltages to power the electrical loads. The coupled electromechanical equations of motion are derived using Newtonian mechanics and Kirchhoff's circuit laws. The free vibration behavior is investigated for devices with identical (tuned) and nonidentical (mistuned) piezoelectric support structures and electrical loads. These devices have complex-valued, speed-dependent eigenvalues and eigenvectors as a result of gyroscopic effects caused by their constant rotation. The characteristics of the complex-valued eigensolutions are related to physical behavior of the device's vibration. The free vibration behaviors differ significantly for tuned and mistuned devices. Due to gyroscopic effects, the proof mass in the tuned device vibrates in either forward or backward decaying circular orbits in single-mode free response. This is proven analytically for all tuned devices, regardless of the device's specific parameters or operating speed. For mistuned devices, the proof mass has decaying elliptical forward and backward orbits. The eigenvalues are shown to be sensitive to changes in the electrical load resistances. Closed-form solutions for the eigenvalues are derived for open and close circuits. At high rotation speeds these devices experience critical speeds and instability.
Indefinite damping in mechanical systems and gyroscopic stabilization
DEFF Research Database (Denmark)
Kliem, Wolfhard; Pommer, Christian
2009-01-01
This paper deals with gyroscopic stabilization of the unstable system Mx + D(x) over dot + K-x = 0, with positive definite mass and stiffness matrices M and K, respectively, and an indefinite damping matrix D. The main question if for which skew-symmetric matrices G the system Mx (D+ G)(x) over dot...... + K-x = 0 can become stable? After investigating special cases we find an appropriat solution of the Lyapunov matrix equation for the general case. Examples show the deviation of the stability limit found by the Lyapunov method from the exact value....
International Nuclear Information System (INIS)
Wen, Xiao; De-Wen, Liu; Yang, Liu; Xiao-Su, Yi; Lin, Cong
2008-01-01
In the space environment, the precision of fibre optic gyroscopes (FOGs) degrades because of space radiation. Photonic components of FOGs are affected by radiation, especially the polarization-maintaining (PM) fibre coil. In relation to the space radiation environment characteristic, we have carried out a series of radiation experiments on a PM fibre coil with 60 Co radiation source at different dose rates. Based on the experimental results, the formula between the PM-fibre loss and radiation dose rate is built, and the relation between the precision of FOG and radiation dose is obtained accordingly. The results strongly show that the precision of our FOG degrades owing to the attenuation of the polarization-maintaining fibre, which provides theoretical foundation for the radiation-resistant design of the FOG
On dynamics and control of vibratory gyroscopes with special spherical symmetry
CSIR Research Space (South Africa)
Shatalov, M
2006-05-01
Full Text Available It was shown in 1985 by Acad. V. Zhuravlev that the angular rate of a pure vibrating mode excited in a vibratory gyroscope with spherical symmetry is proportional to an inertial angular rate of the gyroscope. The effect is three dimensional...
Stability analysis of the Gyroscopic Power Take-Off wave energy point absorber
DEFF Research Database (Denmark)
Nielsen, Søren R. K.; Zhang, Zili; Kramer, Morten Mejlhede
2015-01-01
The Gyroscopic Power Take-Off (GyroPTO) wave energy point absorber consists of a float rigidly connected to a lever. The operational principle is somewhat similar to that of the so-called gyroscopic hand wrist exercisers, where the rotation of the float is brought forward by the rotational particle...
Design and fabrication of a biomimetic gyroscope inspired by the fly's haltere
Droogendijk, H.; Brookhuis, Robert Anton; de Boer, Meint J.; Sanders, Remco G.P.; Krijnen, Gijsbertus J.M.
2012-01-01
We report on the design and fabrication of a MEMS-based gyroscopic system inspired by the fly's haltere system. Two types of so-called biomimetic gyroscopes have been designed, fabricated and their drive mode has been characterized. First measurements indicate excitable gyropscopes with natural
Design and fabrication of a biomimetic gyroscope inspired by the fly’s haltere
Droogendijk, H.; Brookhuis, Robert Anton; de Boer, Meint J.; Sanders, Remco G.P.; Krijnen, Gijsbertus J.M.
2013-01-01
We report on the design and fabrication of a MEMS-based gyroscopic system inspired by the fly’s haltere system. Two types of so-called biomimetic gyroscopes have been designed, fabricated and partially characterized. First measurements indicate excitable gyropscopes with natural frequencies in the
Circuit, especially for digital nuclear gyroscope systems
International Nuclear Information System (INIS)
Lowdenslager, J.R.
1974-01-01
The circuit with at least one or two spin generator shows a digital phase synchronizing loop in solid-state construction without movable mechanical parts. It is stable, may be turned in one direction any number of times without saturation, and also remains phase-synchronized when input signals are turned off. For this purpose, crystal oscillators with certain resonance frequencies are used. The spin generators are coupled at the outled side with filtering, squaring, and differential connections generating control impulses synchronous to the spin generators. Step divider circuits are connected to the oscillators, which act upon flip-flop registers. This is controlled by the filtering, squaring, and differential connections. Furthermore, field proportional control circuits with registers, advancing and delay circuits are provided, the registers being connected at the outlet side with digital adders and subtractors. The digital adder serves inertial-related purposes. (DG) [de
The prototype design of the Stanford Relativity Gyro Experiment
Parkinson, Bradford W.; Everitt, C. W. Francis; Turneaure, John P.; Parmley, Richard T.
1987-01-01
The Stanford Relativity Gyroscope Experiment constitutes a fundamental test of Einstein's General Theory of Relativity, probing such heretofore untested aspects of the theory as those that relate to spin by means of drag-free satellite-borne gyroscopes. General Relativity's prediction of two orthogonal precessions (motional and geodetic) for a perfect Newtonian gyroscope in polar orbit has not yet been experimentally assessed, and will mark a significant advancement in experimental gravitation. The technology employed in the experiment has been under development for 25 years at NASA's Marshall Space Flight Center. Four fused quartz gyroscopes will be used.
Optimal Design of a Center Support Quadruple Mass Gyroscope (CSQMG
Directory of Open Access Journals (Sweden)
Tian Zhang
2016-04-01
Full Text Available This paper reports a more complete description of the design process of the Center Support Quadruple Mass Gyroscope (CSQMG, a gyro expected to provide breakthrough performance for flat structures. The operation of the CSQMG is based on four lumped masses in a circumferential symmetric distribution, oscillating in anti-phase motion, and providing differential signal extraction. With its 4-fold symmetrical axes pattern, the CSQMG achieves a similar operation mode to Hemispherical Resonant Gyroscopes (HRGs. Compared to the conventional flat design, four Y-shaped coupling beams are used in this new pattern in order to adjust mode distribution and enhance the synchronization mechanism of operation modes. For the purpose of obtaining the optimal design of the CSQMG, a kind of applicative optimization flow is developed with a comprehensive derivation of the operation mode coordination, the pseudo mode inhibition, and the lumped mass twisting motion elimination. The experimental characterization of the CSQMG was performed at room temperature, and the center operation frequency is 6.8 kHz after tuning. Experiments show an Allan variance stability 0.12°/h (@100 s and a white noise level about 0.72°/h/√Hz, which means that the CSQMG possesses great potential to achieve navigation grade performance.
Track Detection in Railway Sidings Based on MEMS Gyroscope Sensors
Broquetas, Antoni; Comerón, Adolf; Gelonch, Antoni; Fuertes, Josep M.; Castro, J. Antonio; Felip, Damià; López, Miguel A.; Pulido, José A.
2012-01-01
The paper presents a two-step technique for real-time track detection in single-track railway sidings using low-cost MEMS gyroscopes. The objective is to reliably know the path the train has taken in a switch, diverted or main road, immediately after the train head leaves the switch. The signal delivered by the gyroscope is first processed by an adaptive low-pass filter that rejects noise and converts the temporal turn rate data in degree/second units into spatial turn rate data in degree/meter. The conversion is based on the travelled distance taken from odometer data. The filter is implemented to achieve a speed-dependent cut-off frequency to maximize the signal-to-noise ratio. Although direct comparison of the filtered turn rate signal with a predetermined threshold is possible, the paper shows that better detection performance can be achieved by processing the turn rate signal with a filter matched to the rail switch curvature parameters. Implementation aspects of the track detector have been optimized for real-time operation. The detector has been tested with both simulated data and real data acquired in railway campaigns. PMID:23443376
Topological dynamics of gyroscopic and Floquet lattices from Newton's laws
Lee, Ching Hua; Li, Guangjie; Jin, Guliuxin; Liu, Yuhan; Zhang, Xiao
2018-02-01
Despite intense interest in realizing topological phases across a variety of electronic, photonic, and mechanical platforms, the detailed microscopic origin of topological behavior often remains elusive. To bridge this conceptual gap, we show how hallmarks of topological modes—boundary localization and chirality—emerge from Newton's laws in mechanical topological systems. We first construct a gyroscopic lattice with analytically solvable edge modes, and show how the Lorentz and spring restoring forces conspire to support very robust "dangling bond" boundary modes. The chirality and locality of these modes intuitively emerges from microscopic balancing of restoring forces and cyclotron tendencies. Next, we introduce the highlight of this work, an experimentally realistic mechanical nonequilibrium (Floquet) Chern lattice driven by ac electromagnets. Through appropriate synchronization of the ac driving protocol, the Floquet lattice is "pushed around" by a rotating potential analogous to an object washed ashore by water waves. Besides hosting "dangling bond" chiral modes analogous to the gyroscopic boundary modes, our Floquet Chern lattice also supports peculiar half-period chiral modes with no static analog, i.e., analogs of anomalous Floquet Chern insulators edge modes. With key parameters controlled electronically, our setup has the advantage of being dynamically tunable for applications involving arbitrary Floquet modulations. The physical intuition gleaned from our two prototypical topological systems is applicable not just to arbitrarily complicated mechanical systems, but also photonic and electrical topological setups.
Three-Axis Attitude Estimation Using Rate-Integrating Gyroscopes
Crassidis, John L.; Markley, F. Landis
2016-01-01
Traditionally, attitude estimation has been performed using a combination of external attitude sensors and internal three-axis gyroscopes. There are many studies of three-axis attitude estimation using gyros that read angular rates. Rate-integrating gyros measure integrated rates or angular displacements, but three-axis attitude estimation using these types of gyros has not been as fully investigated. This paper derives a Kalman filtering framework for attitude estimation using attitude sensors coupled with rate- integrating gyroscopes. In order to account for correlations introduced by using these gyros, the state vector must be augmented, compared with filters using traditional gyros that read angular rates. Two filters are derived in this paper. The first uses an augmented state-vector form that estimates attitude, gyro biases, and gyro angular displacements. The second ignores correlations, leading to a filter that estimates attitude and gyro biases only. Simulation comparisons are shown for both filters. The work presented in this paper focuses only on attitude estimation using rate-integrating gyros, but it can easily be extended to other applications such as inertial navigation, which estimates attitude and position.
A complete solution for GP-B's gyroscopic precession by retarded gravitational theory
Tang, Keyun
Mainstream physicists generally believe that Mercury’s Perihelion precession and GP-B’ gyroscopic precession are two of the strongest evidences supporting Einstein’ curved spacetime and general relativity. However, most classical literatures and textbooks (e.g. Ohanain: Gravitation and Spacetime) paint an incorrect picture of Mercury’s orbit anomaly, namely Mercury’s perihelion precessed 43 arc-seconds per century; a correct picture should be that Mercury rotated 43 arc-seconds per century more than along Newtonian theoretical orbit. The essence of Le Verrier’s and Newcomb’s observation and analysis is that the angular speed of Mercury is slightly faster than the Newtonian theoretical value. The complete explanation to Mercury’s orbit anomaly should include two factors, perihelion precession is one of two factors, in addition, the change of orbital radius will also cause a change of angular speed, which is another component of Mercury's orbital anomaly. If Schwarzschild metric is correct, then the solution of the Schwarzschild orbit equation must contain three non-ignorable items. The first corresponds to Newtonian ellipse; the second is a nonlinear perturbation with increasing amplitude, which causes the precession of orbit perihelion; this is just one part of the angular speed anomaly of Mercury; the third part is a linear perturbation, corresponding to a similar figure of the Newton's ellipse, but with a minimal radius; this makes no contribution to the perihelion precession of the Schwarzschild orbit, but makes the Schwarzschild orbital radius slightly smaller, leading to a slight increase in Mercury’s angular speed. All classical literatures of general relativity ignored this last factor, which is a gross oversight. If you correctly take all three factors into consideration, the final result is that the difference between the angles rotated along Schwarzschild’s orbit and the angle rotated along Newton’s orbit for one hundred years should
Behavior of a test gyroscope moving towards a rotating traversable wormhole
Energy Technology Data Exchange (ETDEWEB)
Chakraborty, Chandrachur [Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai, 400005 India (India); Pradhan, Parthapratim, E-mail: chandrachur.chakraborty@tifr.res.in, E-mail: pppradhan77@gmail.com [Department of Physics, Vivekananda Satabarshiki Mahavidyalaya, Manikpara, West Midnapur, 721513 India (India)
2017-03-01
The geodesic structure of the Teo wormhole is briefly discussed and some observables are derived that promise to be of use in detecting a rotating traversable wormhole indirectly, if it does exist. We also deduce the exact Lense-Thirring (LT) precession frequency of a test gyroscope moving toward a rotating traversable Teo wormhole. The precession frequency diverges on the ergoregion, a behavior intimately related to and governed by the geometry of the ergoregion, analogous to the situation in a Kerr spacetime. Interestingly, it turns out that here the LT precession is inversely proportional to the angular momentum ( a ) of the wormhole along the pole and around it in the strong gravity regime, a behavior contrasting with its direct variation with a in the case of other compact objects. In fact, divergence of LT precession inside the ergoregion can also be avoided if the gyro moves with a non-zero angular velocity in a certain range. As a result, the spin precession frequency of the gyro can be made finite throughout its whole path, even very close to the throat, during its travel to the wormhole. Furthermore, it is evident from our formulation that this spin precession not only arises due to curvature or rotation of the spacetime but also due to the non-zero angular velocity of the spin when it does not move along a geodesic in the strong gravity regime. If in the future, interstellar travel indeed becomes possible through a wormhole or at least in its vicinity, our results would prove useful in determining the behavior of a test gyroscope which is known to serve as a fundamental navigation device.
Modeling of Thermal Phase Noise in a Solid Core Photonic Crystal Fiber-Optic Gyroscope.
Song, Ningfang; Ma, Kun; Jin, Jing; Teng, Fei; Cai, Wei
2017-10-26
A theoretical model of the thermal phase noise in a square-wave modulated solid core photonic crystal fiber-optic gyroscope has been established, and then verified by measurements. The results demonstrate a good agreement between theory and experiment. The contribution of the thermal phase noise to the random walk coefficient of the gyroscope is derived. A fiber coil with 2.8 km length is used in the experimental solid core photonic crystal fiber-optic gyroscope, showing a random walk coefficient of 9.25 × 10 -5 deg/√h.
Spherical gyroscopic moment stabilizer for attitude control of microsatellites
Keshtkar, Sajjad; Moreno, Jaime A.; Kojima, Hirohisa; Uchiyama, Kenji; Nohmi, Masahiro; Takaya, Keisuke
2018-02-01
This paper presents a new and improved concept of recently proposed two-degrees of freedom spherical stabilizer for triaxial orientation of microsatellites. The analytical analysis of the advantages of the proposed mechanism over the existing inertial attitude control devices are introduced. The extended equations of motion of the stabilizing satellite including the spherical gyroscope, for control law design and numerical simulations, are studied in detail. A new control algorithm based on continuous high-order sliding mode algorithms, for managing the torque produced by the stabilizer and therefore the attitude control of the satellite in the presence of perturbations/uncertainties, is presented. Some numerical simulations are carried out to prove the performance of the proposed mechanism and control laws.
Realization of a topological phase transition in a gyroscopic lattice
Mitchell, Noah P.; Nash, Lisa M.; Irvine, William T. M.
2018-03-01
Topological metamaterials exhibit unusual behaviors at their boundaries, such as unidirectional chiral waves, that are protected by a topological feature of their band structures. The ability to tune such a material through a topological phase transition in real time could enable the use of protected waves for information storage and readout. Here we dynamically tune through a topological phase transition by breaking inversion symmetry in a metamaterial composed of interacting gyroscopes. Through the transition, we track the divergence of the edge modes' localization length and the change in Chern number characterizing the topology of the material's band structure. This Rapid Communication provides a new axis with which to tune the response of mechanical topological metamaterials.
Design and Simulation of A Novel Piezoelectric AlN-Si Cantilever Gyroscope
Directory of Open Access Journals (Sweden)
Jian Yang
2018-02-01
Full Text Available A novel design of piezoelectric aluminum nitride (AlN-Si composite cantilever gyroscope is proposed in this paper. The cantilever is stimulated to oscillate in plane by two inverse voltages which are applied on the two paralleled drive electrodes, respectively. The whole working principles are deduced, which based on the piezoelectric equation and elastic vibration equation. In this work, a cantilever gyroscope has been simulated and optimized by COMSOL Multiphysics 5.2a. The drive mode frequency is 87.422 kHz, and the sense mode frequency is 87.414 kHz. The theoretical sensitivity of this gyroscope is 0.145 pm/◦/s. This gyroscope has a small size and simple structure. It will be a better choice for the consumer electronics.
Analysis of the gyroscopic stabilization of a system of rigid bodies
DEFF Research Database (Denmark)
Kliem, Wolfhard; Seyranian, Alexander P.
1997-01-01
We study the gyroscopic stability of a three-body system. A new method of finding stability regions, based on mechanism and criteria for gyroscopic stabilization, is presented. Of particular interest in this connection is the theory of interaction of eigenvalues. This leads to a complete 3......-dimensional analysis, which shows the regions of stability, divergence, and flutter of a simple model of a rotating spaceship....
Design and Implementation of a Dual-Mass MEMS Gyroscope with High Shock Resistance.
Gao, Yang; Huang, Libin; Ding, Xukai; Li, Hongsheng
2018-03-30
This paper presents the design and implementation of a dual-mass MEMS gyroscope with high shock resistance by improving the in-phase frequency of the gyroscope and by using a two-stage elastic stopper mechanism and proposes a Simulink shock model of the gyroscope equipped with the two-stage stopper mechanism, which is a very efficient method to evaluate the shock resistance of the gyroscope. The structural design takes into account both the mechanical sensitivity and the shock resistance. The design of the primary structure and the analysis of the stopper mechanism are first introduced. Based on the expression of the restoring force of the stopper beam, the analytical shock response model of the gyroscope is obtained. By this model, the shock response of the gyroscope is theoretically analyzed, and the appropriate structural parameters are obtained. Then, the correctness of the model is verified by finite element (FE) analysis, where the contact collision analysis is introduced in detail. The simulation results show that the application of the two-stage elastic stopper mechanism can effectively improve the shock resistance by more than 1900 g and 1500 g in the x - and y -directions, respectively. Finally, experimental verifications are carried out by using a machete hammer on the micro-gyroscope prototype fabricated by the deep dry silicon on glass (DDSOG) technology. The results show that the shock resistance of the prototype along the x -, y - and z -axes all exceed 10,000 g. Moreover, the output of the gyroscope can return to normal in about 2 s.
Dynamics of Molecular Gyroscopes Created by Strong Optical Fields
Mullin, Amy
2015-03-01
We explore the behavior of molecules in ultra-high angular momentum states prepared in an optical centrifuge and detected with transient IR absorption spectroscopy. In the optical centrifuge, the polarizable electron cloud of molecules interacts with the electric field of linearly polarized light that angularly accelerates over the time of the optical pulse. The centrifuge pulse is generated by combining oppositely chirped pulsed of light. Trapped molecules are driven into high angular momentum states that are spatially oriented with the optical field and have energies far above the average at 300 K. High resolution transient IR spectroscopy reveals the dynamics of collisional energy transfer for the super-rotors. Polarization-dependent studies show that the initial angular momentum orientation persists for many collisions, indicating that molecules in an optical centrifuge behave as quantum gyroscopes. Time-dependent population and energy profiles for individual J- states give information about the dynamics of super-rotors. Research support provided by NSF and the University of Maryland.
Atrial Fibrillation Detection via Accelerometer and Gyroscope of a Smartphone.
Lahdenoja, Olli; Hurnanen, Tero; Iftikhar, Zuhair; Nieminen, Sami; Knuutila, Timo; Saraste, Antti; Kiviniemi, Tuomas; Vasankari, Tuija; Airaksinen, Juhani; Pankaala, Mikko; Koivisto, Tero
2018-01-01
We present a smartphone-only solution for the detection of atrial fibrillation (AFib), which utilizes the built-in accelerometer and gyroscope sensors [inertial measurement unit, (IMU)] in the detection. Depending on the patient's situation, it is possible to use the developed smartphone application either regularly or occasionally for making a measurement of the subject. The smartphone is placed on the chest of the patient who is adviced to lay down and perform a noninvasive recording, while no external sensors are needed. After that, the application determines whether the patient suffers from AFib or not. The presented method has high potential to detect paroxysmal ("silent") AFib from large masses. In this paper, we present the preprocessing, feature extraction, feature analysis, and classification results of the envisioned AFib detection system based on clinical data acquired with a standard mobile phone equipped with Google Android OS. Test data was gathered from 16 AFib patients (validated against ECG), as well as a control group of 23 healthy individuals with no diagnosed heart diseases. We obtained an accuracy of 97.4% in AFib versus healthy classification (a sensitivity of 93.8% and a specificity of 100%). Due to the wide availability of smart devices/sensors with embedded IMU, the proposed methods could potentially also scale to other domains such as embedded body-sensor networks.
Online technique for detecting state of onboard fiber optic gyroscope
International Nuclear Information System (INIS)
Miao, Zhiyong; He, Kunpeng; Pang, Shuwan; Xu, Dingjie; Tian, Chunmiao
2015-01-01
Although angle random walk (ARW) of fiber optic gyroscope (FOG) has been well modeled and identified before being integrated into the high-accuracy attitude control system of satellite, aging and unexpected failures can affect the performance of FOG after launch, resulting in the variation of ARW coefficient. Therefore, the ARW coefficient can be regarded as an indicator of “state of health” for FOG diagnosis in some sense. The Allan variance method can be used to estimate ARW coefficient of FOG, however, it requires a large amount of data to be stored. Moreover, the procedure of drawing slope lines for estimation is painful. To overcome the barriers, a weighted state-space model that directly models the ARW to obtain a nonlinear state-space model was established for FOG. Then, a neural extended-Kalman filter algorithm was implemented to estimate and track the variation of ARW in real time. The results of experiment show that the proposed approach is valid to detect the state of FOG. Moreover, the proposed technique effectively avoids the storage of data
A Micro Dynamically Tuned Gyroscope with Adjustable Static Capacitance
Directory of Open Access Journals (Sweden)
Lun Kong
2013-02-01
Full Text Available This paper presents a novel micro dynamically tuned gyroscope (MDTG with adjustable static capacitance. First, the principle of MDTG is theoretically analyzed. Next, some simulations under the optimized structure parameters are given as a reference for the mask design of the rotor wafer and electrode plates. As two key components, the process flows of the rotor wafer and electrode plates are described in detail. All the scanning electron microscopy (SEM photos show that the fabrication process is effective and optimized. Then, an assembly model is designed for the static capacitance adjustable MDTG, whose static capacitance can be changed by rotating the lower electrode plate support and substituting gasket rings of different thicknesses. Thus, the scale factor is easily changeable. Afterwards, the digitalized closed-loop measurement circuit is simulated. The discrete correction and decoupling modules are designed to make the closed-loop stable and cross-coupling effect small. The dual axis closed-loop system bandwidths can reach more than 60 Hz and the dual axis scale factors are completely symmetrical. All the simulation results demonstrate the proposed fabrication of the MDTG can meet the application requirements. Finally, the paper presents the test results of static and dynamic capacitance values which are consistent with the simulation values.
Gyroscopic stimulation of the semicircular canals during sensory deprivation.
Newsom, B. D.; Brady, J. F.; Stumm, J. E.
1971-01-01
A static object revolving at a constant velocity is stationary with respect to that environment. When the object is rotated outside the plane of spin, a gyroscopic or cross-coupled acceleration is produced orthogonal to the two planes of rotation. In this situation, a man feels himself moving in a direction other than that which his visual or proprioceptive sensors perceive. The conflict in spatial orientation is the cross-coupled acceleration imposed on the semicircular canals. This perceptual conflict and the thresholds involved were studied by partial isolation of the physiological stimuli through sensory deprivation. Subjects weighted to neutral buoyancy were submerged in 94 F water in the dark. The subjects were then rotated while being revolved about a displaced axis. Thresholds for detection of angular acceleration were higher than those reported in the literature for detection of acceleration of a single plane. This discrepancy may be attributable to the length of time the stimuli are imposed to each of the canals and the cupular response periods.
Free vibration of elastically supported thin cylinders including gyroscopic effects
CSIR Research Space (South Africa)
Loveday, PW
1998-10-29
Full Text Available [ The equations D[R[ 747723 JSV 106:2 "Issue# MS 1560 VIBRATION OF THIN CYLINDERS 442 required for this procedure\\ including the gyroscopic terms\\ are included in Appendix A[ The displacement functions can then be written as follows] W"x# C0 cosh a0xa C1 sinh a0... xa C2 cos g1xa C3 sin g1xa epx:a0C4 cos qxa C5 sin qxa 1 e px:a0C6 cos qxa C7 sin qxa 1 "6a# V"x# A0C0 cosh a0xa A0C1 sinh a0xa A2C2 cos g1xa A2C3 sin g1xa epx:a$"A4C4 A5C5# cos qxa "A4C5 A5C4# sin qxa % e px:a$"A4C6 A5C7# cos...
Online technique for detecting state of onboard fiber optic gyroscope
Energy Technology Data Exchange (ETDEWEB)
Miao, Zhiyong; He, Kunpeng, E-mail: pengkhe@126.com; Pang, Shuwan [Department of Automation, Harbin Engineering University, Harbin, Heilongjiang 150000 (China); Xu, Dingjie [School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin, Heilongjiang 150000 (China); Tian, Chunmiao [Department of Information and Communication Engineering, Harbin Engineering University, Harbin, Heilongjiang 150000 (China)
2015-02-15
Although angle random walk (ARW) of fiber optic gyroscope (FOG) has been well modeled and identified before being integrated into the high-accuracy attitude control system of satellite, aging and unexpected failures can affect the performance of FOG after launch, resulting in the variation of ARW coefficient. Therefore, the ARW coefficient can be regarded as an indicator of “state of health” for FOG diagnosis in some sense. The Allan variance method can be used to estimate ARW coefficient of FOG, however, it requires a large amount of data to be stored. Moreover, the procedure of drawing slope lines for estimation is painful. To overcome the barriers, a weighted state-space model that directly models the ARW to obtain a nonlinear state-space model was established for FOG. Then, a neural extended-Kalman filter algorithm was implemented to estimate and track the variation of ARW in real time. The results of experiment show that the proposed approach is valid to detect the state of FOG. Moreover, the proposed technique effectively avoids the storage of data.
International Nuclear Information System (INIS)
Velikoseltsev, A A; Luk'yanov, D P; Vinogradov, V I; Shreiber, K U
2014-01-01
A brief survey of the history of the invention and development of super-large laser gyroscopes (SLLGs) is presented. The basic results achieved using SLLGs in geodesy, seismology, fundamental physics and other fields are summarised. The concept of SLLG design, specific features of construction and implementation are considered, as well as the prospects of applying the present-day optical technologies to laser gyroscope engineering. The possibilities of using fibre-optical gyroscopes in seismologic studies are analysed and the results of preliminary experimental studies are presented. (laser gyroscopes)
Energy Technology Data Exchange (ETDEWEB)
Velikoseltsev, A A; Luk' yanov, D P [St. Petersburg Electrotechnical University ' ' LETI' ' , St. Petersburg (Russian Federation); Vinogradov, V I [OJSC Tambov factory Elektropribor (Russian Federation); Shreiber, K U [Forschungseinrichtung Satellitengeodaesie, Technosche Universitaet Muenchen, Geodaetisches Observatorium Wettzell, Sackenrieder str. 25, 93444 Bad Koetzting (Germany)
2014-12-31
A brief survey of the history of the invention and development of super-large laser gyroscopes (SLLGs) is presented. The basic results achieved using SLLGs in geodesy, seismology, fundamental physics and other fields are summarised. The concept of SLLG design, specific features of construction and implementation are considered, as well as the prospects of applying the present-day optical technologies to laser gyroscope engineering. The possibilities of using fibre-optical gyroscopes in seismologic studies are analysed and the results of preliminary experimental studies are presented. (laser gyroscopes)
Energy Technology Data Exchange (ETDEWEB)
Saez Garcia, E.; Fuente Martin, P.L. (HUNOSA, Madrid (Spain))
1988-01-01
This entry tries to revise the most used method for the direction transition what with exterior and interior using plumbs in connected with vertical shaft coalmines. A technical and economic cooperation was also realized between the indicated method and the gyroscope.
International Nuclear Information System (INIS)
Mian, Muhammad Umer; Khir, M. H. Md.; Tang, T. B.; Dennis, John Ojur; Riaz, Kashif; Iqbal, Abid; Bazaz, Shafaat A.
2015-01-01
Pre-fabrication, behavioural and performance analysis with computer aided design (CAD) tools is a common and fabrication cost effective practice. In light of this we present a simulation methodology for a dual-mass oscillator based 3 Degree of Freedom (3-DoF) MEMS gyroscope. 3-DoF Gyroscope is modeled through lumped parameter models using equivalent circuit elements. These equivalent circuits consist of elementary components which are counterpart of their respective mechanical components, used to design and fabricate 3-DoF MEMS gyroscope. Complete designing of equivalent circuit model, mathematical modeling and simulation are being presented in this paper. Behaviors of the equivalent lumped models derived for the proposed device design are simulated in MEMSPRO T-SPICE software. Simulations are carried out with the design specifications following design rules of the MetalMUMPS fabrication process. Drive mass resonant frequencies simulated by this technique are 1.59 kHz and 2.05 kHz respectively, which are close to the resonant frequencies found by the analytical formulation of the gyroscope. The lumped equivalent circuit modeling technique proved to be a time efficient modeling technique for the analysis of complex MEMS devices like 3-DoF gyroscopes. The technique proves to be an alternative approach to the complex and time consuming couple field analysis Finite Element Analysis (FEA) previously used
Energy Technology Data Exchange (ETDEWEB)
Mian, Muhammad Umer, E-mail: umermian@gmail.com; Khir, M. H. Md.; Tang, T. B. [Department of Electrical and Electronic Engineering, Universiti Teknologi PETRONAS, Tronoh, Perak (Malaysia); Dennis, John Ojur [Department of Fundamental & Applied Sciences, Universiti Teknologi PETRONAS, Tronoh, Perak (Malaysia); Riaz, Kashif; Iqbal, Abid [Faculty of Electronics Engineering, GIK Institute of Engineering Sciences and Technology, Topi, Khyber Pakhtunkhaw (Pakistan); Bazaz, Shafaat A. [Department of Computer Science, Center for Advance Studies in Engineering, Islamabad (Pakistan)
2015-07-22
Pre-fabrication, behavioural and performance analysis with computer aided design (CAD) tools is a common and fabrication cost effective practice. In light of this we present a simulation methodology for a dual-mass oscillator based 3 Degree of Freedom (3-DoF) MEMS gyroscope. 3-DoF Gyroscope is modeled through lumped parameter models using equivalent circuit elements. These equivalent circuits consist of elementary components which are counterpart of their respective mechanical components, used to design and fabricate 3-DoF MEMS gyroscope. Complete designing of equivalent circuit model, mathematical modeling and simulation are being presented in this paper. Behaviors of the equivalent lumped models derived for the proposed device design are simulated in MEMSPRO T-SPICE software. Simulations are carried out with the design specifications following design rules of the MetalMUMPS fabrication process. Drive mass resonant frequencies simulated by this technique are 1.59 kHz and 2.05 kHz respectively, which are close to the resonant frequencies found by the analytical formulation of the gyroscope. The lumped equivalent circuit modeling technique proved to be a time efficient modeling technique for the analysis of complex MEMS devices like 3-DoF gyroscopes. The technique proves to be an alternative approach to the complex and time consuming couple field analysis Finite Element Analysis (FEA) previously used.
Towards a fully integrated optical gyroscope using whispering gallery modes resonators
Amrane, T.; Jager, J.-B.; Jager, T.; Calvo, V.; Léger, J.-M.
2017-11-01
Since the developments of lasers and the optical fibers in the 70s, the optical gyroscopes have been subject to an intensive research to improve both their resolution and stability performances. However the best optical gyroscopes currently on the market, the ring laser gyroscope and the interferometer fiber optic gyroscope are still macroscopic devices and cannot address specific applications where size and weight constraints are critical. One solution to overcome these limitations could be to use an integrated resonator as a sensitive part to build a fully Integrated Optical Resonant Gyroscope (IORG). To keep a high rotation sensitivity, which is usually degraded when downsizing this kind of optical sensors based on the Sagnac effect, the resonator has to exhibit a very high quality factor (Q): as detailed in equation (1) where the minimum rotation rate resolution for an IORG is given as a function of the resonator characteristics (Q and diameter D) and of the global system optical system characteristics (i.e. SNR and bandwidth B), the higher the Q×D product, the lower the resolution.
Zhang, Xian; Zhou, Binquan; Li, Hong; Zhao, Xinghua; Mu, Weiwei; Wu, Wenfeng
2017-10-01
Navigation technology is crucial to the national defense and military, which can realize the measurement of orientation, positioning, attitude and speed for moving object. Inertial navigation is not only autonomous, real-time, continuous, hidden, undisturbed but also no time-limited and environment-limited. The gyroscope is the core component of the inertial navigation system, whose precision and size are the bottleneck of the performance. However, nuclear magnetic resonance gyroscope is characteristic of the advantage of high precision and small size. Nuclear magnetic resonance gyroscope can meet the urgent needs of high-tech weapons and equipment development of new generation. This paper mainly designs a set of photoelectric signal processing system for nuclear magnetic resonance gyroscope based on FPGA, which process and control the information of detecting laser .The photoelectric signal with high frequency carrier is demodulated by in-phase and quadrature demodulation method. Finally, the processing system of photoelectric signal can compensate the residual magnetism of the shielding barrel and provide the information of nuclear magnetic resonance gyroscope angular velocity.
The GINGERino ring laser gyroscope, seismological observations at one year from the first light
Simonelli, Andreino; Belfi, Jacopo; Beverini, Nicolò; Di Virgilio, Angela; Carelli, Giorgio; Maccioni, Enrico; De Luca, Gaetano; Saccorotti, Gilberto
2016-04-01
The GINGERino ring laser gyroscope (RLG) is a new large observatory-class RLG located in Gran Sasso underground laboratory (LNGS), one national laboratory of the INFN (Istituto Nazionale di Fisica Nucleare). The GINGERino apparatus funded by INFN in the context of a larger project of fundamental physics is intended as a pathfinder instrument to reach the high sensitivity needed to observe general relativity effects; more details are found at the URL (https://web2.infn.it/GINGER/index.php/it/). The sensitivity reached by our instrument in the first year after the set up permitted us to acquire important seismological data of ground rotations during the transit of seismic waves generated by seisms at different epicentral distances. RLGs are in fact the best sensors for capturing the rotational motions associated with the transit of seismic waves, thanks to the optical measurement principle, these instruments are in fact insensitive to translations. Ground translations are recorded by two seismometers: a Nanometrics Trillium 240 s and Guralp CMG 3T 360 s, the first instrument is part of the national earthquake monitoring program of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and provides the ground translation data to be compared to the RLG rotational data. We report the waveforms and the seismological analysis of some seismic events recorded during our first year of activity inside the LNGS laboratory.
High-Q microsphere resonators for angular velocity sensing in gyroscopes
International Nuclear Information System (INIS)
An, Panlong; Zheng, Yongqiu; Yan, Shubin; Xue, Chenyang; Liu, Jun; Wang, Wanjun
2015-01-01
A resonator gyroscope based on the Sagnac effect is proposed using a core unit that is generated by water-hydrogen flame melting. The relationship between the quality factor Q and diameter D is revealed. The Q factor of the spectral lines of the microsphere cavity coupling system, which uses tapered fibers, is found to be 10 6 or more before packaging with a low refractive curable ultraviolet polymer, although it drops to approximately 10 5 after packaging. In addition, a rotating test platform is built, and the transmission spectrum and discriminator curves of a microsphere cavity with Q of 3.22×10 6 are measured using a semiconductor laser (linewidth less than 1 kHz) and a real-time proportional-integral circuit tracking and feedback technique. Equations fitting the relation between the voltage and angular rotation rate are obtained. According to the experimentally measured parameters, the sensitivity of the microsphere-coupled system can reach 0.095 ∘ /s
A Novel Artificial Fish Swarm Algorithm for Recalibration of Fiber Optic Gyroscope Error Parameters
Directory of Open Access Journals (Sweden)
Yanbin Gao
2015-05-01
Full Text Available The artificial fish swarm algorithm (AFSA is one of the state-of-the-art swarm intelligent techniques, which is widely utilized for optimization purposes. Fiber optic gyroscope (FOG error parameters such as scale factors, biases and misalignment errors are relatively unstable, especially with the environmental disturbances and the aging of fiber coils. These uncalibrated error parameters are the main reasons that the precision of FOG-based strapdown inertial navigation system (SINS degraded. This research is mainly on the application of a novel artificial fish swarm algorithm (NAFSA on FOG error coefficients recalibration/identification. First, the NAFSA avoided the demerits (e.g., lack of using artificial fishes’ pervious experiences, lack of existing balance between exploration and exploitation, and high computational cost of the standard AFSA during the optimization process. To solve these weak points, functional behaviors and the overall procedures of AFSA have been improved with some parameters eliminated and several supplementary parameters added. Second, a hybrid FOG error coefficients recalibration algorithm has been proposed based on NAFSA and Monte Carlo simulation (MCS approaches. This combination leads to maximum utilization of the involved approaches for FOG error coefficients recalibration. After that, the NAFSA is verified with simulation and experiments and its priorities are compared with that of the conventional calibration method and optimal AFSA. Results demonstrate high efficiency of the NAFSA on FOG error coefficients recalibration.
A novel artificial fish swarm algorithm for recalibration of fiber optic gyroscope error parameters.
Gao, Yanbin; Guan, Lianwu; Wang, Tingjun; Sun, Yunlong
2015-05-05
The artificial fish swarm algorithm (AFSA) is one of the state-of-the-art swarm intelligent techniques, which is widely utilized for optimization purposes. Fiber optic gyroscope (FOG) error parameters such as scale factors, biases and misalignment errors are relatively unstable, especially with the environmental disturbances and the aging of fiber coils. These uncalibrated error parameters are the main reasons that the precision of FOG-based strapdown inertial navigation system (SINS) degraded. This research is mainly on the application of a novel artificial fish swarm algorithm (NAFSA) on FOG error coefficients recalibration/identification. First, the NAFSA avoided the demerits (e.g., lack of using artificial fishes' pervious experiences, lack of existing balance between exploration and exploitation, and high computational cost) of the standard AFSA during the optimization process. To solve these weak points, functional behaviors and the overall procedures of AFSA have been improved with some parameters eliminated and several supplementary parameters added. Second, a hybrid FOG error coefficients recalibration algorithm has been proposed based on NAFSA and Monte Carlo simulation (MCS) approaches. This combination leads to maximum utilization of the involved approaches for FOG error coefficients recalibration. After that, the NAFSA is verified with simulation and experiments and its priorities are compared with that of the conventional calibration method and optimal AFSA. Results demonstrate high efficiency of the NAFSA on FOG error coefficients recalibration.
Adaptive Global Sliding Mode Control for MEMS Gyroscope Using RBF Neural Network
Directory of Open Access Journals (Sweden)
Yundi Chu
2015-01-01
Full Text Available An adaptive global sliding mode control (AGSMC using RBF neural network (RBFNN is proposed for the system identification and tracking control of micro-electro-mechanical system (MEMS gyroscope. Firstly, a new kind of adaptive identification method based on the global sliding mode controller is designed to update and estimate angular velocity and other system parameters of MEMS gyroscope online. Moreover, the output of adaptive neural network control is used to adjust the switch gain of sliding mode control dynamically to approach the upper bound of unknown disturbances. In this way, the switch item of sliding mode control can be converted to the output of continuous neural network which can weaken the chattering in the sliding mode control in contrast to the conventional fixed gain sliding mode control. Simulation results show that the designed control system can get satisfactory tracking performance and effective estimation of unknown parameters of MEMS gyroscope.
A low noise photoelectric signal acquisition system applying in nuclear magnetic resonance gyroscope
Lu, Qilin; Zhang, Xian; Zhao, Xinghua; Yang, Dan; Zhou, Binquan; Hu, Zhaohui
2017-10-01
The nuclear magnetic resonance gyroscope serves as a new generation of strong support for the development of high-tech weapons, it solves the core problem that limits the development of the long-playing seamless navigation and positioning. In the NMR gyroscope, the output signal with atomic precession frequency is detected by the probe light, the final crucial photoelectric signal of the probe light directly decides the quality of the gyro signal. But the output signal has high sensitivity, resolution and measurement accuracy for the photoelectric detection system. In order to detect the measured signal better, this paper proposed a weak photoelectric signal rapid acquisition system, which has high SNR and the frequency of responded signal is up to 100 KHz to let the weak output signal with high frequency of the NMR gyroscope can be detected better.
Directory of Open Access Journals (Sweden)
Yan Deng
2014-10-01
Full Text Available A novel multifrequency excitation (MFE method is proposed to realize rapid and accurate dynamic testing of micromachined gyroscope chips. Compared with the traditional sweep-frequency excitation (SFE method, the computational time for testing one chip under four modes at a 1-Hz frequency resolution and 600-Hz bandwidth was dramatically reduced from 10 min to 6 s. A multifrequency signal with an equal amplitude and initial linear-phase-difference distribution was generated to ensure test repeatability and accuracy. The current test system based on LabVIEW using the SFE method was modified to use the MFE method without any hardware changes. The experimental results verified that the MFE method can be an ideal solution for large-scale dynamic testing of gyroscope chips and gyroscopes.
Enhanced sensitivity in a butterfly gyroscope with a hexagonal oblique beam
Energy Technology Data Exchange (ETDEWEB)
Xiao, Dingbang; Cao, Shijie; Hou, Zhanqiang, E-mail: houzhanqiang@nudt.edu.cn; Chen, Zhihua; Wang, Xinghua; Wu, Xuezhong [College of Mechatronics Engineering and Automation, National University of Defense Technology, Changsha, Hunan, 410073 (China)
2015-04-15
A new approach to improve the performance of a butterfly gyroscope is developed. The methodology provides a simple way to improve the gyroscope’s sensitivity and stability, by reducing the resonant frequency mismatch between the drive and sense modes. This method was verified by simulations and theoretical analysis. The size of the hexagonal section oblique beam is the major factor that influences the resonant frequency mismatch. A prototype, which has the appropriately sized oblique beam, was fabricated using precise, time-controlled multilayer pre-buried masks. The performance of this prototype was compared with a non-tuned gyroscope. The scale factor of the prototype reaches 30.13 mV/ °/s, which is 15 times larger than that obtained from the non-tuned gyroscope. The bias stability of the prototype is 0.8 °/h, which is better than the 5.2 °/h of the non-tuned devices.
Directory of Open Access Journals (Sweden)
Zhentao Wang
2012-01-01
Full Text Available Fault detection and isolation (FDI in rotor systems often faces the problem that the system dynamics is dependent on the rotor rotary frequency because of the gyroscopic effect. In unbalance excited rotor systems, the continuously distributed unbalances are hard to be determined or estimated accurately. The unbalance forces as disturbances make fault detection more complicated. The aim of this paper is to develop linear time invariant (LTI FDI methods (i.e., with constant parameters for rotor systems under consideration of gyroscopic effect and disturbances. Two approaches to describe the gyroscopic effect, that is, as unknown inputs and as model uncertainties, are investigated. Based on these two approaches, FDI methods are developed and the results are compared regarding the resulting FDI performances. Results are obtained by the application in a rotor test rig. Restrictions for the application of these methods are discussed.
Larkin, K.; Ghommem, M.; Abdelkefi, A.
2018-05-01
Capacitive-based sensing microelectromechanical (MEMS) and nanoelectromechanical (NEMS) gyroscopes have significant advantages over conventional gyroscopes, such as low power consumption, batch fabrication, and possible integration with electronic circuits. However, inadequacies in the modeling of these inertial sensors have presented issues of reliability and functionality of micro-/nano-scale gyroscopes. In this work, a micromechanical model is developed to represent the unique microstructure of nanocrystalline materials and simulate the response of micro-/nano-gyroscope comprising an electrostatically-actuated cantilever beam with a tip mass at the free end. Couple stress and surface elasticity theories are integrated into the classical Euler-Bernoulli beam model in order to derive a size-dependent model. This model is then used to investigate the influence of size-dependent effects on the static pull-in instability, the natural frequencies and the performance output of gyroscopes as the scale decreases from micro-to nano-scale. The simulation results show significant changes in the static pull-in voltage and the natural frequency as the scale of the system is decreased. However, the differential frequency between the two vibration modes of the gyroscope is observed to drastically decrease as the size of the gyroscope is reduced. As such, the frequency-based operation mode may not be an efficient strategy for nano-gyroscopes. The results show that a strong coupling between the surface elasticity and material structure takes place when smaller grain sizes and higher void percentages are considered.
Design and analysis of a novel dual-mass MEMS resonant output gyroscope
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Yang Gao
2018-02-01
Full Text Available This paper presents the design and analysis of a novel dual-mass microelectromechanical systems (MEMS resonant output gyroscope (ROG, which can effectively eliminate the influence of common-mode disturbance, such as the linear acceleration, on the gyroscope working mode by the design of dual-mass form, as well as on the frequency outputs of the double-ended tuning fork (DETF resonators by the differential arrangement. The concept of the ROG is introduced first. Then the dynamics of the gyroscope and the force-frequency characteristics of the DETF resonator are theoretically analyzed. By establishing the distribution coefficient of force and the reasonable equivalent of the force-frequency characteristics of the DETF resonator, the accurate expression of the device sensitivity is obtained. Based on the analysis results, the leverage mechanism and the DETF resonator are designed in detail. Then the configuration of the gyroscope, a dual-mass structure, is given. Finally, the validity of the analysis and design are verified by numerical simulations.
Sadaghzadeh N, Nargess; Poshtan, Javad; Wagner, Achim; Nordheimer, Eugen; Badreddin, Essameddin
2014-03-01
Based on a cascaded Kalman-Particle Filtering, gyroscope drift and robot attitude estimation method is proposed in this paper. Due to noisy and erroneous measurements of MEMS gyroscope, it is combined with Photogrammetry based vision navigation scenario. Quaternions kinematics and robot angular velocity dynamics with augmented drift dynamics of gyroscope are employed as system state space model. Nonlinear attitude kinematics, drift and robot angular movement dynamics each in 3 dimensions result in a nonlinear high dimensional system. To reduce the complexity, we propose a decomposition of system to cascaded subsystems and then design separate cascaded observers. This design leads to an easier tuning and more precise debugging from the perspective of programming and such a setting is well suited for a cooperative modular system with noticeably reduced computation time. Kalman Filtering (KF) is employed for the linear and Gaussian subsystem consisting of angular velocity and drift dynamics together with gyroscope measurement. The estimated angular velocity is utilized as input of the second Particle Filtering (PF) based observer in two scenarios of stochastic and deterministic inputs. Simulation results are provided to show the efficiency of the proposed method. Moreover, the experimental results based on data from a 3D MEMS IMU and a 3D camera system are used to demonstrate the efficiency of the method. © 2013 ISA Published by ISA All rights reserved.
Abedi, Maryam; Jin, Tian; Sun, Kewen
2015-08-31
In this paper, the efficiency of the gyroscopic mounting method is studied for a highly dynamic GNSS receiver's reference oscillator for reducing signal loss. Analyses are performed separately in two phases, atmospheric and upper atmospheric flights. Results show that the proposed mounting reduces signal loss, especially in parts of the trajectory where its probability is the highest. This reduction effect appears especially for crystal oscillators with a low elevation angle g-sensitivity vector. The gyroscopic mounting influences frequency deviation or jitter caused by dynamic loads on replica carrier and affects the frequency locked loop (FLL) as the dominant tracking loop in highly dynamic GNSS receivers. In terms of steady-state load, the proposed mounting mostly reduces the frequency deviation below the one-sigma threshold of FLL (1σ(FLL)). The mounting method can also reduce the frequency jitter caused by sinusoidal vibrations and reduces the probability of signal loss in parts of the trajectory where the other error sources accompany this vibration load. In the case of random vibration, which is the main disturbance source of FLL, gyroscopic mounting is even able to suppress the disturbances greater than the three-sigma threshold of FLL (3σ(FLL)). In this way, signal tracking performance can be improved by the gyroscopic mounting method for highly dynamic GNSS receivers.
Analysis of the Gyroscopic Stabilization of a System of Rigid Bodies
DEFF Research Database (Denmark)
Kliem, Wolfhard; Kliem, Wolfhard
1996-01-01
We study the gyroscopic of a three-body system. A new method offinding stability regions, based on mechanism and criteria for gyroscopicstabilization, is presented. Of particular interest in this connection isthe theory of interaction of eigenvalues. This leads to a complete 3-dimensionalanalysis......, which shows the regions of stability, divergence, and flutter ofa simple model of a rotating spaceship....
Application of MEMS Accelerometers and Gyroscopes in Fast Steering Mirror Control Systems
Directory of Open Access Journals (Sweden)
Jing Tian
2016-03-01
Full Text Available In a charge-coupled device (CCD-based fast steering mirror (FSM tracking control system, high control bandwidth is the most effective way to enhance the closed-loop performance. However, the control system usually suffers a great deal from mechanical resonances and time delays induced by the low sampling rate of CCDs. To meet the requirements of high precision and load restriction, fiber-optic gyroscopes (FOGs are usually used in traditional FSM tracking control systems. In recent years, the MEMS accelerometer and gyroscope are becoming smaller and lighter and their performance have improved gradually, so that they can be used in a fast steering mirror (FSM to realize the stabilization of the line-of-sight (LOS of the control system. Therefore, a tentative approach to implement a CCD-based FSM tracking control system, which uses MEMS accelerometers and gyroscopes as feedback components and contains an acceleration loop, a velocity loop and a position loop, is proposed. The disturbance suppression of the proposed method is the product of the error attenuation of the acceleration loop, the velocity loop and the position loop. Extensive experimental results show that the MEMS accelerometers and gyroscopes can act the similar role as the FOG with lower cost for stabilizing the LOS of the FSM tracking control system.
A universal gyroscope driving circuit with 70dB amplitude control range
Abdelghany, Mohamed A.
2010-08-01
A CMOS variable gain driving circuit with output signal amplitude control for gyroscopes with wide range of quality factors is presented. The driving circuit can be used for gyroscopes with Q values higher than 500. The circuit uses a current-commutating switching mixer to control the gyroscope driving signal level. Conventional driving circuits use automatic gain control (AGC) which suffers from limited linear range and the need for an off-chip capacitor for the peak detector and loop filter. Two stage variable gain amplifier is used in the proposed design to ensure enough gain for oscillation for such a wide range of quality factors. Analog and digital amplitude control methods are used to cover wide range of driving signal amplitude with enough accuracy to hit the maximum driving signal level without sacrificing gyroscope linearity. Due to the high DC gain of the amplifier chain, DC offset resulting from mismatches might saturate the amplifier output. DC offset correction is employed using a secondary negative feedback loop. The proposed driving circuit is being fabricated in 0.6μm CMOS technology. © 2010 IEEE.
Study on VCSEL laser heating chip in nuclear magnetic resonance gyroscope
Liang, Xiaoyang; Zhou, Binquan; Wu, Wenfeng; Jia, Yuchen; Wang, Jing
2017-10-01
In recent years, atomic gyroscope has become an important direction of inertial navigation. Nuclear magnetic resonance gyroscope has a stronger advantage in the miniaturization of the size. In atomic gyroscope, the lasers are indispensable devices which has an important effect on the improvement of the gyroscope performance. The frequency stability of the VCSEL lasers requires high precision control of temperature. However, the heating current of the laser will definitely bring in the magnetic field, and the sensitive device, alkali vapor cell, is very sensitive to the magnetic field, so that the metal pattern of the heating chip should be designed ingeniously to eliminate the magnetic field introduced by the heating current. In this paper, a heating chip was fabricated by MEMS process, i.e. depositing platinum on semiconductor substrates. Platinum has long been considered as a good resistance material used for measuring temperature The VCSEL laser chip is fixed in the center of the heating chip. The thermometer resistor measures the temperature of the heating chip, which can be considered as the same temperature of the VCSEL laser chip, by turning the temperature signal into voltage signal. The FPGA chip is used as a micro controller, and combined with PID control algorithm constitute a closed loop control circuit. The voltage applied to the heating resistor wire is modified to achieve the temperature control of the VCSEL laser. In this way, the laser frequency can be controlled stably and easily. Ultimately, the temperature stability can be achieved better than 100mK.
Costa, L. Filipe; Natário, José
2016-05-01
We present a pedagogical discussion of the Coriolis field, emphasizing its not-so-well-understood aspects. We show that this field satisfies the field equations of the so-called Newton-Cartan theory, a generalization of Newtonian gravity that is covariant under changes of arbitrarily rotating and accelerated frames. Examples of solutions of this theory are given, including the Newtonian analogue of the Gödel universe. We discuss how to detect the Coriolis field by its effect on gyroscopes, of which the gyrocompass is an example. Finally, using a similar framework, we discuss the Coriolis field generated by mass currents in general relativity, and its measurement by the gravity probe B and LAGEOS/LARES experiments.
Directory of Open Access Journals (Sweden)
Svetoslav Ganchev Nikolov
2015-07-01
Full Text Available The study of the dynamic behavior of a rigid body with one fixed point (gyroscope has a long history. A number of famous mathematicians and mechanical engineers have devoted enormous time and effort to clarify the role of dynamic effects on its movement (behavior – stable, periodic, quasi-periodic or chaotic. The main objectives of this review are: 1 to outline the characteristic features of the theory of dynamical systems and 2 to reveal the specific properties of the motion of a rigid body with one fixed point (gyroscope.This article consists of six sections. The first section addresses the main concepts of the theory of dynamical systems. Section two presents the main theoretical results (obtained so far concerning the dynamic behavior of a solid with one fixed point (gyroscope. Section three examines the problem of gyroscopic stabilization. Section four deals with the non-linear (chaotic dynamics of the gyroscope. Section five is a brief analysis of the gyroscope applications in engineering. The final section provides conclusions and generalizations on why the theory of dynamical systems should be used in the study of the movement of gyroscopic systems.
Fabrication and analysis of a micro-machined tri-axis gyroscope
Tsai, Nan-Chyuan; Sue, Chung-Yang
2008-11-01
This paper presents an innovative micro-gyroscope design. Solely by SOI (silicon on insulator) fabrication technology and wet etching, the proposed micro-gyroscope can be produced in batch and is capable of detecting three-axis angular rates. The induced motions of all individual seismic mass modules are designed to respond in the directions orthogonal to each other in order to decouple the obtained measurements. In our work, three pairs of high-resolution differential capacitors with signal processing circuits are employed to measure the angular velocity components in three axes. On the other hand, the drive electrode comb is used to constantly vibrate the outer-ring in the tangential direction by a sinusoidal voltage. The signal bandwidth is increased by distributed translational proof masses (DTPM), placed 90° apart orderly. Each individual proof mass of DTPM is designed with natural frequency discrepancy and constrained to move in the radial direction so that the superior mode matching can be easily, to some extent, achieved. The suspension flexures are particularly designed to resist planar displacements in the drive mode but increase the stroke of tilting angular displacement in the sense mode. By considering the complicated geometry of the suspension flexures, FEM (finite element method) is employed to examine the potential maximum induced mechanical stress. The dynamic equations of the proposed gyroscope are established so that the embedded gyroscopic effects are explicitly unveiled. More importantly, the efficacy of the drive and sense circuit modules are verified by commercial softwares Hspice and Multisim. By intensive computer simulations and preliminary experimental studies, the resolution, bandwidth and decoupling capability of the tri-axis gyroscope are expected to be fairly enhanced if a certain degree of trade-off is preset.Corrections were made to figure 5 in this article on 3 October 2008. The corrected electronic version is identical to the
Fabrication and analysis of a micro-machined tri-axis gyroscope
International Nuclear Information System (INIS)
Tsai, Nan-Chyuan; Sue, Chung-Yang
2008-01-01
This paper presents an innovative micro-gyroscope design. Solely by SOI (silicon on insulator) fabrication technology and wet etching, the proposed micro-gyroscope can be produced in batch and is capable of detecting three-axis angular rates. The induced motions of all individual seismic mass modules are designed to respond in the directions orthogonal to each other in order to decouple the obtained measurements. In our work, three pairs of high-resolution differential capacitors with signal processing circuits are employed to measure the angular velocity components in three axes. On the other hand, the drive electrode comb is used to constantly vibrate the outer-ring in the tangential direction by a sinusoidal voltage. The signal bandwidth is increased by distributed translational proof masses (DTPM), placed 90° apart orderly. Each individual proof mass of DTPM is designed with natural frequency discrepancy and constrained to move in the radial direction so that the superior mode matching can be easily, to some extent, achieved. The suspension flexures are particularly designed to resist planar displacements in the drive mode but increase the stroke of tilting angular displacement in the sense mode. By considering the complicated geometry of the suspension flexures, FEM (finite element method) is employed to examine the potential maximum induced mechanical stress. The dynamic equations of the proposed gyroscope are established so that the embedded gyroscopic effects are explicitly unveiled. More importantly, the efficacy of the drive and sense circuit modules are verified by commercial softwares Hspice and Multisim. By intensive computer simulations and preliminary experimental studies, the resolution, bandwidth and decoupling capability of the tri-axis gyroscope are expected to be fairly enhanced if a certain degree of trade-off is preset. Corrections were made to figure 5 in this article on 3 October 2008. The corrected electronic version is identical to the
Rhudy, Matthew B; Mahoney, Joseph M
2018-04-01
The goal of this work is to compare the differences between various step counting algorithms using both accelerometer and gyroscope measurements from wrist and ankle-mounted sensors. Participants completed four different conditions on a treadmill while wearing an accelerometer and gyroscope on the wrist and the ankle. Three different step counting techniques were applied to the data from each sensor type and mounting location. It was determined that using gyroscope measurements allowed for better performance than the typically used accelerometers, and that ankle-mounted sensors provided better performance than those mounted on the wrist.
Song, Xuerui; Wang, Liujun; Feng, Fupan; Lou, Liren; Diao, Wenting; Duan, Chongdi
2018-03-01
Developing gyroscopes based on quantum systems are important for inertial sensing applications, and its underlying physics is of fundamental interest. In this paper, we proposed a new type of gyroscope based on the Berry phase generated during rotation of the quantum system by using a single 13C nuclear spin coupled with a nearby nitrogen-vacancy center in diamond. Due to the atom-scale size of the quantum system, rotation information can be obtained with high spatial resolution. The gyroscope can be manipulated at room temperature and without the need for a strong magnetic field, which is also beneficial to its further applications.
Interface circuit for a multiple-beam tuning-fork gyroscope with high quality factors
Wang, Ren
This research work presents the design, theoretical analysis, fabrication, interface electronics, and experimental results of a Silicon-On-Insulator (SOI) based Multiple-Beam Tuning-Fork Gyroscope (MB-TFG). Based on a numerical model of Thermo-Elastic Damping (TED), a Multiple-Beam Tuning-Fork Structure (MB-TFS) is designed with high Quality factors (Qs) in its two operation modes. A comprehensive theoretical analysis of the MB-TFG design is conducted to relate the design parameters to its operation parameters and further performance parameters. In conjunction with a mask that defines the device through trenches to alleviate severe fabrication effect on anchor loss, a simple one-mask fabrication process is employed to implement this MB-TFG design on SOI wafers. The fabricated MB-TFGs are tested with PCB-level interface electronics and a thorough comparison between the experimental results and a theoretical analysis is conducted to verify the MB-TFG design and accurately interpret the measured performance. The highest measured Qs of the fabricated MB-TFGs in vacuum are 255,000 in the drive-mode and 103,000 in the sense-mode, at a frequency of 15.7kHz. Under a frequency difference of 4Hz between the two modes (operation frequency is 16.8kHz) and a drive-mode vibration amplitude of 3.0um, the measured rate sensitivity is 80mVpp/°/s with an equivalent impedance of 6MQ. The calculated overall rate resolution of this device is 0.37/hrhiElz, while the measured Angle Random Walk (ARW) and bias instability are 6.67°/'vhr and 95°/hr, respectively.
Development and evaluation of a gyroscope-based wheel rotation monitor for manual wheelchair users.
Hiremath, Shivayogi V; Ding, Dan; Cooper, Rory A
2013-07-01
To develop and evaluate a wireless gyroscope-based wheel rotation monitor (G-WRM) that can estimate speeds and distances traveled by wheelchair users during regular wheelchair propulsion as well as wheelchair sports such as handcycling, and provide users with real-time feedback through a smartphone application. The speeds and the distances estimated by the G-WRM were compared with the criterion measures by calculating absolute difference, mean difference, and percentage errors during a series of laboratory-based tests. Intraclass correlations (ICC) and the Bland-Altman plots were also used to assess the agreements between the G-WRM and the criterion measures. In addition, battery life and wireless data transmission tests under a number of usage conditions were performed. The percentage errors for the angular velocities, speeds, and distances obtained from three prototype G-WRMs were less than 3% for all the test trials. The high ICC values (ICC (3,1) > 0.94) and the Bland-Altman plots indicate excellent agreement between the estimated speeds and distances by the G-WRMs and the criterion measures. The battery life tests showed that the device could last for 35 hours in wireless mode and 139 hours in secure digital card mode. The wireless data transmission tests indicated less than 0.3% of data loss. The results indicate that the G-WRM is an appropriate tool for tracking a spectrum of wheelchair-related activities from regular wheelchair propulsion to wheelchair sports such as handcycling. The real-time feedback provided by the G-WRM can help wheelchair users self-monitor their everyday activities.
Feng, Yibo; Li, Xisheng; Zhang, Xiaojuan
2015-05-13
We present an adaptive algorithm for a system integrated with micro-electro-mechanical systems (MEMS) gyroscopes and a compass to eliminate the influence from the environment, compensate the temperature drift precisely, and improve the accuracy of the MEMS gyroscope. We use a simplified drift model and changing but appropriate model parameters to implement this algorithm. The model of MEMS gyroscope temperature drift is constructed mostly on the basis of the temperature sensitivity of the gyroscope. As the state variables of a strong tracking Kalman filter (STKF), the parameters of the temperature drift model can be calculated to adapt to the environment under the support of the compass. These parameters change intelligently with the environment to maintain the precision of the MEMS gyroscope in the changing temperature. The heading error is less than 0.6° in the static temperature experiment, and also is kept in the range from 5° to -2° in the dynamic outdoor experiment. This demonstrates that the proposed algorithm exhibits strong adaptability to a changing temperature, and performs significantly better than KF and MLR to compensate the temperature drift of a gyroscope and eliminate the influence of temperature variation.
Directory of Open Access Journals (Sweden)
Yibo Feng
2015-05-01
Full Text Available We present an adaptive algorithm for a system integrated with micro-electro-mechanical systems (MEMS gyroscopes and a compass to eliminate the influence from the environment, compensate the temperature drift precisely, and improve the accuracy of the MEMS gyroscope. We use a simplified drift model and changing but appropriate model parameters to implement this algorithm. The model of MEMS gyroscope temperature drift is constructed mostly on the basis of the temperature sensitivity of the gyroscope. As the state variables of a strong tracking Kalman filter (STKF, the parameters of the temperature drift model can be calculated to adapt to the environment under the support of the compass. These parameters change intelligently with the environment to maintain the precision of the MEMS gyroscope in the changing temperature. The heading error is less than 0.6° in the static temperature experiment, and also is kept in the range from 5° to −2° in the dynamic outdoor experiment. This demonstrates that the proposed algorithm exhibits strong adaptability to a changing temperature, and performs significantly better than KF and MLR to compensate the temperature drift of a gyroscope and eliminate the influence of temperature variation.
Calibration of atomic trajectories in a large-area dual-atom-interferometer gyroscope
Yao, Zhan-Wei; Lu, Si-Bin; Li, Run-Bing; Luo, Jun; Wang, Jin; Zhan, Ming-Sheng
2018-01-01
We propose and demonstrate a method for calibrating atomic trajectories in a large-area dual-atom-interferometer gyroscope. The atom trajectories are monitored by modulating and delaying the Raman transition, and they are precisely calibrated by controlling the laser orientation and the bias magnetic field. To improve the immunity to the gravity effect and the common phase noise, the symmetry and the overlap of two large-area atomic interference loops are optimized by calibrating the atomic trajectories and by aligning the Raman-laser orientations. The dual-atom-interferometer gyroscope is applied in the measurement of the Earth's rotation. The sensitivity is 1.2 ×10-6 rad s -1 Hz-1/2, and the long-term stability is 6.2 ×10-8 rad/s at 2000 s.
International Nuclear Information System (INIS)
Celikel, Oguz
2011-01-01
This paper presents the application of the vector modulation method (VMM) to an open-loop interferometric fiber optic gyroscope, called the north finder capability gyroscope (NFCG), designed and assembled in TUBITAK UME (National Metrology Institute of Turkey). The method contains a secondary modulation/demodulation circuit with an AD630 chip, depending on the periodic variation of the orientation of the sensing coil sensitive surface vector with respect to geographic north at a laboratory latitude and collection of dc voltage at the secondary demodulation circuit output in the time domain. The resultant dc voltage proportional to the first-kind Bessel function based on Sagnac phase shift for the first order is obtained as a result of vector modulation together with the Earth's rotation. A new model function is developed and introduced to evaluate the angular errors of the NFCG with VMM in finding geographic north
A single-ended CMOS sensing circuit for MEMS gyroscope with noise cancellation
Elsayed, Mohannad Yomn
2010-06-01
In this work, a complete single-ended readout circuit for capacitive MEMS gyroscope using chopper stabilization technique is presented. A novel noise cancellation technique is used to get rid of the bias noise. The circuit offers superior performance over state of the art readout circuits in terms of cost, gain, and noise for the given area and power consumption. The full circuit exhibits a gain of 58dB, a power dissipation of 1.3mW and an input referred noise of 12nV/√Hz. This would significantly improve the overall sensitivity of the gyroscope. The full circuit has been fabricated in 0.6um CMOS technology and it occupies an area of 0.4mm × 1mm. © 2010 IEEE.
International Nuclear Information System (INIS)
Yau, H.-T.
2008-01-01
This Letter presents a robust control scheme to generalized projective synchronization between two identical two-degrees-of-freedom heavy symmetric gyroscopes with dead zone nonlinear inputs. Because of the nonlinear terms of the gyroscope system, the system exhibits complex and chaotic motions. By the Lyapunov stability theory with control terms, two suitable sliding surfaces are proposed to ensure the stability of the controlled closed-loop system in sliding mode. Then, two sliding mode controllers (SMC) are designed to guarantee the hitting of the sliding surfaces even when the control inputs contain dead-zone nonlinearity. This method allows us to arbitrarily direct the scaling factor onto a desired value. Numerical simulations show that this method works very well for the proposed controller
A single-ended CMOS sensing circuit for MEMS gyroscope with noise cancellation
Elsayed, Mohannad Yomn; Emira, Ahmed; Sedky, Sherif M.; Habib, S. E. D.
2010-01-01
In this work, a complete single-ended readout circuit for capacitive MEMS gyroscope using chopper stabilization technique is presented. A novel noise cancellation technique is used to get rid of the bias noise. The circuit offers superior performance over state of the art readout circuits in terms of cost, gain, and noise for the given area and power consumption. The full circuit exhibits a gain of 58dB, a power dissipation of 1.3mW and an input referred noise of 12nV/√Hz. This would significantly improve the overall sensitivity of the gyroscope. The full circuit has been fabricated in 0.6um CMOS technology and it occupies an area of 0.4mm × 1mm. © 2010 IEEE.
Noise Reduction of MEMS Gyroscope Based on Direct Modeling for an Angular Rate Signal
Directory of Open Access Journals (Sweden)
Liang Xue
2015-02-01
Full Text Available In this paper, a novel approach for processing the outputs signal of the microelectromechanical systems (MEMS gyroscopes was presented to reduce the bias drift and noise. The principle for the noise reduction was presented, and an optimal Kalman filter (KF was designed by a steady-state filter gain obtained from the analysis of KF observability. In particular, the true angular rate signal was directly modeled to obtain an optimal estimate and make a self-compensation for the gyroscope without needing other sensor’s information, whether in static or dynamic condition. A linear fit equation that describes the relationship between the KF bandwidth and modeling parameter of true angular rate was derived from the analysis of KF frequency response. The test results indicated that the MEMS gyroscope having an ARW noise of 4.87°/h0.5 and a bias instability of 44.41°/h were reduced to 0.4°/h0.5 and 4.13°/h by the KF under a given bandwidth (10 Hz, respectively. The 1σ estimated error was reduced from 1.9°/s to 0.14°/s and 1.7°/s to 0.5°/s in the constant rate test and swing rate test, respectively. It also showed that the filtered angular rate signal could well reflect the dynamic characteristic of the input rate signal in dynamic conditions. The presented algorithm is proved to be effective at improving the measurement precision of the MEMS gyroscope.
Chip-Scale Combinatorial Atomic Navigator (C-SCAN) Low Drift Nuclear Spin Gyroscope
2018-01-01
suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704...spin-exchange relaxation in a finite magnetic field. We operated the gyroscope using a Ramsey-type interrogation sequence with nuclear spin precession...shift by a factor of 105. Here we use the approach of a Ramsey clock interrogation scheme, where the optical pumping, free evolution, and measurement
Project of a laser gyroscope to determine continuously the Earth's rotation.
Blinov, N. S.; Zharov, V. E.; Sazhin, M. V.; Fedoseev, E. N.; Vlasov, B. I.; Rusakov, V. K.
The Time Service of the Sternberg State Astronomical Institute together with specialists of VNIIFTRI began to work at the project of the laser gyroscope to determine continuously the Earth's rotation. It is assumed to measure both the high-frequency variations with periods of 100 - 1000 sec and the low-frequency variations with periods of a few days. It gives the opportunity to combine these data with the VLBI data.
A new systematic calibration method of ring laser gyroscope inertial navigation system
Wei, Guo; Gao, Chunfeng; Wang, Qi; Wang, Qun; Xiong, Zhenyu; Long, Xingwu
2016-10-01
Inertial navigation system has been the core component of both military and civil navigation systems. Before the INS is put into application, it is supposed to be calibrated in the laboratory in order to compensate repeatability error caused by manufacturing. Discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed theories of error inspiration and separation in detail and presented a new systematic calibration method for ring laser gyroscope inertial navigation system. Error models and equations of calibrated Inertial Measurement Unit are given. Then proper rotation arrangement orders are depicted in order to establish the linear relationships between the change of velocity errors and calibrated parameter errors. Experiments have been set up to compare the systematic errors calculated by filtering calibration result with those obtained by discrete calibration result. The largest position error and velocity error of filtering calibration result are only 0.18 miles and 0.26m/s compared with 2 miles and 1.46m/s of discrete calibration result. These results have validated the new systematic calibration method and proved its importance for optimal design and accuracy improvement of calibration of mechanically dithered ring laser gyroscope inertial navigation system.
Analysis of Dynamic Performance of a Kalman Filter for Combining Multiple MEMS Gyroscopes
Directory of Open Access Journals (Sweden)
Liang Xue
2014-11-01
Full Text Available In this paper, the dynamic performance of a Kalman filter (KF was analyzed, which is used to combine multiple measurements of a gyroscopes array to reduce the noise and improve the accuracy of the individual sensors. A principle for accuracy improvement by the KF was briefly presented to obtain an optimal estimate of input rate signal. In particular, the influences of some crucial factors on the KF dynamic performance were analyzed by simulations such as the factors input signal frequency, signal sampling, and KF filtering rate. Finally, a system that was comprised of a six-gyroscope array was designed and implemented to test the dynamic performance. Experimental results indicated that the 1σ error for the combined rate signal was reduced to about 0.2°/s in the constant rate test, which was a reduction by a factor of more than eight compared to the single gyroscope. The 1σ error was also reduced from 1.6°/s to 0.48°/s in the swing test. It showed that the estimated angular rate signal could well reflect the dynamic characteristic of the input signal in dynamic conditions.
EVALUATION METHOD FOR PARASITIC EFFECTS OF THE ELECTRO-OPTICAL MODULATOR IN A FIBER OPTIC GYROSCOPE
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S. A. Volkovskiy
2016-09-01
Full Text Available Subject of Research.The paper proposes an original method for studying the parasitic effects in the electro-optic modulator of the fiber optic gyroscope. Proposed method is based on the usage of a special waveform phase modulation signal. Method. The essence of the proposed method lies in modification of serrodyne modulation signal, thereby providing a periodic displacement of the phase difference signal to the maximum of the interference curve. In this case, the intensity level reflects the influence of parasitic effects with the degree of manifestation being determined by the sequence of voltage control signals applied to the modulator. Enumeration of combinations of control signals and the corresponding intensity levels gives the possibility to observe an empirical dependence of the parasitic effects and use it later for compensation. Main Results. The efficiency of the proposed method is demonstrated by the program model of the fiber optic gyroscope. The results of the method application on a production sample of the device were obtained. Comparison with the results of direct estimate of the parasitic intensity modulation effect testifies to the effectiveness of the proposed method. Practical Relevance. The method can be used as a diagnostic tool to quantify the influence of parasitic effects in the electro-optic modulator of the fiber optic gyroscope as well as for their subsequent compensation.
Structural-acoustic coupling effects on the non-vacuum packaging vibratory cylinder gyroscope.
Xi, Xiang; Wu, Xuezhong; Wu, Yulie; Zhang, Yongmeng; Tao, Yi; Zheng, Yu; Xiao, Dingbang
2013-12-13
The resonant shells of vibratory cylinder gyroscopes are commonly packaged in metallic caps. In order to lower the production cost, a portion of vibratory cylinder gyroscopes do not employ vacuum packaging. However, under non-vacuum packaging conditions there can be internal acoustic noise leading to considerable acoustic pressure which is exerted on the resonant shell. Based on the theory of the structural-acoustic coupling, the dynamical behavior of the resonant shell under acoustic pressure is presented in this paper. A finite element (FE) model is introduced to quantitatively analyze the effect of the structural-acoustic coupling. Several main factors, such as sealing cap sizes and degree of vacuum which directly affect the vibration of the resonant shell, are studied. The results indicate that the vibration amplitude and the operating frequency of the resonant shell will be changed when the effect of structural-acoustic coupling is taken into account. In addition, an experiment was set up to study the effect of structural-acoustic coupling on the sensitivity of the gyroscope. A 32.4 mV/°/s increase of the scale factor and a 6.2 Hz variation of the operating frequency were observed when the radial gap size between the resonant shell and the sealing cap was changed from 0.5 mm to 20 mm.
Structural-Acoustic Coupling Effects on the Non-Vacuum Packaging Vibratory Cylinder Gyroscope
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Xiang Xi
2013-12-01
Full Text Available The resonant shells of vibratory cylinder gyroscopes are commonly packaged in metallic caps. In order to lower the production cost, a portion of vibratory cylinder gyroscopes do not employ vacuum packaging. However, under non-vacuum packaging conditions there can be internal acoustic noise leading to considerable acoustic pressure which is exerted on the resonant shell. Based on the theory of the structural-acoustic coupling, the dynamical behavior of the resonant shell under acoustic pressure is presented in this paper. A finite element (FE model is introduced to quantitatively analyze the effect of the structural-acoustic coupling. Several main factors, such as sealing cap sizes and degree of vacuum which directly affect the vibration of the resonant shell, are studied. The results indicate that the vibration amplitude and the operating frequency of the resonant shell will be changed when the effect of structural-acoustic coupling is taken into account. In addition, an experiment was set up to study the effect of structural-acoustic coupling on the sensitivity of the gyroscope. A 32.4 mV/°/s increase of the scale factor and a 6.2 Hz variation of the operating frequency were observed when the radial gap size between the resonant shell and the sealing cap was changed from 0.5 mm to 20 mm.
Directory of Open Access Journals (Sweden)
Liang Xue
2018-01-01
Full Text Available Obtaining a correlation factor is a prerequisite for fusing multiple outputs of a mircoelectromechanical system (MEMS gyroscope array and evaluating accuracy improvement. In this paper, a mathematical statistics method is established to analyze and obtain the practical correlation factor of a MEMS gyroscope array, which solves the problem of determining the Kalman filter (KF covariance matrix Q and fusing the multiple gyroscope signals. The working principle and mathematical model of the sensor array fusion is briefly described, and then an optimal estimate of input rate signal is achieved by using of a steady-state KF gain in an off-line estimation approach. Both theoretical analysis and simulation show that the negative correlation factor has a favorable influence on accuracy improvement. Additionally, a four-gyro array system composed of four discrete individual gyroscopes was developed to test the correlation factor and its influence on KF accuracy improvement. The result showed that correlation factors have both positive and negative values; in particular, there exist differences for correlation factor between the different units in the array. The test results also indicated that the Angular Random Walk (ARW of 1.57°/h0.5 and bias drift of 224.2°/h for a single gyroscope were reduced to 0.33°/h0.5 and 47.8°/h with some negative correlation factors existing in the gyroscope array, making a noise reduction factor of about 4.7, which is higher than that of a uncorrelated four-gyro array. The overall accuracy of the combined angular rate signal can be further improved if the negative correlation factors in the gyroscope array become larger.
International Nuclear Information System (INIS)
Ma, Wei; Lin, Yiyu; Liu, Siqi; Zheng, Xudong; Jin, Zhonghe
2017-01-01
This paper reports a novel oscillation control algorithm for MEMS vibratory gyroscopes using a modified electromechanical amplitude modulation (MEAM) technique, which enhances the robustness against the frequency variation of the driving mode, compared to the conventional EAM (CEAM) scheme. In this approach, the carrier voltage exerted on the proof mass is frequency-modulated by the drive resonant frequency. Accordingly, the pick-up signal from the interface circuit involves a constant-frequency component that contains the amplitude and phase information of the vibration displacement. In other words, this informational detection signal is independent of the mechanical resonant frequency, which varies due to different batches, imprecise micro-fabrication and changing environmental temperature. In this paper, the automatic gain control loop together with the phase-locked loop are simultaneously analyzed using the averaging method and Routh–Hurwitz criterion, deriving the stability condition and the parameter optimization rules of the transient response. Then, a simulation model based on the real system is set up to evaluate the control algorithm. Further, the proposed MEAM method is tested using a field-programmable-gate-array based digital platform on a capacitive vibratory gyroscope. By optimizing the control parameters, the transient response of the drive amplitude reveals a settling time of 45.2 ms without overshoot, according well with the theoretical prediction and simulation results. The first measurement results show that the amplitude variance of the drive displacement is 12 ppm in an hour while the phase standard deviation is as low as 0.0004°. The mode-split gyroscope operating under atmospheric pressure demonstrates an outstanding performance. By virtue of the proposed MEAM method, the bias instability and angle random walk are measured to be 0.9° h −1 (improved by 2.4 times compared to the CEAM method) and 0.068° (√h) −1 (improved by 1
A dynamic system matching technique for improving the accuracy of MEMS gyroscopes
Energy Technology Data Exchange (ETDEWEB)
Stubberud, Peter A., E-mail: stubber@ee.unlv.edu [Department of Electrical and Computer Engineering, University of Nevada, Las Vegas, Las Vegas, NV 89154 (United States); Stubberud, Stephen C., E-mail: scstubberud@ieee.org [Oakridge Technology, San Diego, CA 92121 (United States); Stubberud, Allen R., E-mail: stubberud@att.net [Department of Electrical Engineering and Computer Science, University of California, Irvine, Irvine, CA 92697 (United States)
2014-12-10
A classical MEMS gyro transforms angular rates into electrical values through Euler's equations of angular rotation. Production models of a MEMS gyroscope will have manufacturing errors in the coefficients of the differential equations. The output signal of a production gyroscope will be corrupted by noise, with a major component of the noise due to the manufacturing errors. As is the case of the components in an analog electronic circuit, one way of controlling the variability of a subsystem is to impose extremely tight control on the manufacturing process so that the coefficient values are within some specified bounds. This can be expensive and may even be impossible as is the case in certain applications of micro-electromechanical (MEMS) sensors. In a recent paper [2], the authors introduced a method for combining the measurements from several nominally equal MEMS gyroscopes using a technique based on a concept from electronic circuit design called dynamic element matching [1]. Because the method in this paper deals with systems rather than elements, it is called a dynamic system matching technique (DSMT). The DSMT generates a single output by randomly switching the outputs of several, nominally identical, MEMS gyros in and out of the switch output. This has the effect of 'spreading the spectrum' of the noise caused by the coefficient errors generated in the manufacture of the individual gyros. A filter can then be used to eliminate that part of the spread spectrum that is outside the pass band of the gyro. A heuristic analysis in that paper argues that the DSMT can be used to control the effects of the random coefficient variations. In a follow-on paper [4], a simulation of a DSMT indicated that the heuristics were consistent. In this paper, analytic expressions of the DSMT noise are developed which confirm that the earlier conclusions are valid. These expressions include the various DSMT design parameters and, therefore, can be used as design
A dynamic system matching technique for improving the accuracy of MEMS gyroscopes
International Nuclear Information System (INIS)
Stubberud, Peter A.; Stubberud, Stephen C.; Stubberud, Allen R.
2014-01-01
A classical MEMS gyro transforms angular rates into electrical values through Euler's equations of angular rotation. Production models of a MEMS gyroscope will have manufacturing errors in the coefficients of the differential equations. The output signal of a production gyroscope will be corrupted by noise, with a major component of the noise due to the manufacturing errors. As is the case of the components in an analog electronic circuit, one way of controlling the variability of a subsystem is to impose extremely tight control on the manufacturing process so that the coefficient values are within some specified bounds. This can be expensive and may even be impossible as is the case in certain applications of micro-electromechanical (MEMS) sensors. In a recent paper [2], the authors introduced a method for combining the measurements from several nominally equal MEMS gyroscopes using a technique based on a concept from electronic circuit design called dynamic element matching [1]. Because the method in this paper deals with systems rather than elements, it is called a dynamic system matching technique (DSMT). The DSMT generates a single output by randomly switching the outputs of several, nominally identical, MEMS gyros in and out of the switch output. This has the effect of 'spreading the spectrum' of the noise caused by the coefficient errors generated in the manufacture of the individual gyros. A filter can then be used to eliminate that part of the spread spectrum that is outside the pass band of the gyro. A heuristic analysis in that paper argues that the DSMT can be used to control the effects of the random coefficient variations. In a follow-on paper [4], a simulation of a DSMT indicated that the heuristics were consistent. In this paper, analytic expressions of the DSMT noise are developed which confirm that the earlier conclusions are valid. These expressions include the various DSMT design parameters and, therefore, can be used as design
A dynamic system matching technique for improving the accuracy of MEMS gyroscopes
Stubberud, Peter A.; Stubberud, Stephen C.; Stubberud, Allen R.
2014-12-01
A classical MEMS gyro transforms angular rates into electrical values through Euler's equations of angular rotation. Production models of a MEMS gyroscope will have manufacturing errors in the coefficients of the differential equations. The output signal of a production gyroscope will be corrupted by noise, with a major component of the noise due to the manufacturing errors. As is the case of the components in an analog electronic circuit, one way of controlling the variability of a subsystem is to impose extremely tight control on the manufacturing process so that the coefficient values are within some specified bounds. This can be expensive and may even be impossible as is the case in certain applications of micro-electromechanical (MEMS) sensors. In a recent paper [2], the authors introduced a method for combining the measurements from several nominally equal MEMS gyroscopes using a technique based on a concept from electronic circuit design called dynamic element matching [1]. Because the method in this paper deals with systems rather than elements, it is called a dynamic system matching technique (DSMT). The DSMT generates a single output by randomly switching the outputs of several, nominally identical, MEMS gyros in and out of the switch output. This has the effect of 'spreading the spectrum' of the noise caused by the coefficient errors generated in the manufacture of the individual gyros. A filter can then be used to eliminate that part of the spread spectrum that is outside the pass band of the gyro. A heuristic analysis in that paper argues that the DSMT can be used to control the effects of the random coefficient variations. In a follow-on paper [4], a simulation of a DSMT indicated that the heuristics were consistent. In this paper, analytic expressions of the DSMT noise are developed which confirm that the earlier conclusions are valid. These expressions include the various DSMT design parameters and, therefore, can be used as design tools for DSMT
Uncertainty of angular displacement measurement with a MEMS gyroscope integrated in a smartphone
International Nuclear Information System (INIS)
De Campos Porath, Maurício; Dolci, Ricardo
2015-01-01
Low-cost inertial sensors have recently gained popularity and are now widely used in electronic devices such as smartphones and tablets. In this paper we present the results of a set of experiments aiming to assess the angular displacement measurement errors of a gyroscope integrated in a smartphone of a recent model. The goal is to verify whether these sensors could substitute dedicated electronic inclinometers for the measurement of angular displacement. We estimated a maximum error of 0.3° (sum of expanded uncertainty and maximum absolute bias) for the roll and pitch axes, for a measurement time without referencing up to 1 h. (paper)
Interactive modeling activities in the classroom—rotational motion and smartphone gyroscopes
Pörn, Ray; Braskén, Mats
2016-11-01
The wide-spread availability of smartphones makes them a valuable addition to the measurement equipment in both the physics classroom and the instructional laboratory, encouraging an active interaction between measurements and modeling activities. In this paper we illustrate this interaction by making use of the internal gyroscope of a smartphone to study and measure the rotational dynamics of objects rotating about a fixed axis. The workflow described in this paper has been tested in a classroom setting and found to encourage an exploratory approach to both data collecting and modeling.
Minimal-Learning-Parameter Technique Based Adaptive Neural Sliding Mode Control of MEMS Gyroscope
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Bin Xu
2017-01-01
Full Text Available This paper investigates an adaptive neural sliding mode controller for MEMS gyroscopes with minimal-learning-parameter technique. Considering the system uncertainty in dynamics, neural network is employed for approximation. Minimal-learning-parameter technique is constructed to decrease the number of update parameters, and in this way the computation burden is greatly reduced. Sliding mode control is designed to cancel the effect of time-varying disturbance. The closed-loop stability analysis is established via Lyapunov approach. Simulation results are presented to demonstrate the effectiveness of the method.
Establishment and analysis of coupled dynamic model for dual-mass silicon micro-gyroscope
Wang, Zhanghui; Qiu, Anping; Shi, Qin; Zhang, Taoyuan
2017-12-01
This paper presents a coupled dynamic model for a dual-mass silicon micro-gyroscope (DMSG). It can quantitatively analyze the influence of left-right stiffness difference on the natural frequencies, modal matrix and modal coupling coefficient of the DMSG. The analytic results are verified by using the finite element method (FEM) simulation. The model shows that with the left-right stiffness difference of 1%, the modal coupling coefficient is 12% in the driving direction and 31% in the sensing direction. It also shows that in order to achieve good separation, the stiffness of base beam should be small enough in both the driving and sensing direction.
Efficiency of a gyroscopic device for conversion of mechanical wave energy to electrical energy
DEFF Research Database (Denmark)
Carlsen, Martin; Darula, Radoslav; Gravesen, Jens
2011-01-01
We consider a recently proposed gyroscopic device for conversion of mechanical ocean wave energy to electrical energy. Two models of the device derived from standard engineering mechanics from the literature are analysed, and a model is derived from analytical mechanics considerations. From...... these models, estimates of the power production, eciency, forces and moments are made. We nd that it is possible to extract a signicant amount of energy from an ocean wave using the described device. Further studies are required for a full treatment of the device....
A novel Cs-(129)Xe atomic spin gyroscope with closed-loop Faraday modulation.
Fang, Jiancheng; Wan, Shuangai; Qin, Jie; Zhang, Chen; Quan, Wei; Yuan, Heng; Dong, Haifeng
2013-08-01
We report a novel Cs-(129)Xe atomic spin gyroscope (ASG) with closed-loop Faraday modulation method. This ASG requires approximately 30 min to start-up and 110 °C to operate. A closed-loop Faraday modulation method for measurement of the optical rotation was used in this ASG. This method uses an additional Faraday modulator to suppress the laser intensity fluctuation and Faraday modulator thermal induced fluctuation. We theoretically and experimentally validate this method in the Cs-(129)Xe ASG and achieved a bias stability of approximately 3.25 °∕h.
The rotational velocities evaluation for the engine mounts gyroscopic loads
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Stefan BOGOS
2013-06-01
Full Text Available The default values for the maximum pitch and yaw speeds from CS 23.371, seem to be too conservative that would result in overstressing of the structure.A simplified dynamic simulation is proposed to evaluate more confident velocities for a specific aircraft. The yawing condition is related to the “sudden rudder deflection” and a maneuver with “lateral gust”. The pitching conditions are a result of a “sudden elevator deflection”. The model takes into account the nonlinear effects of the aerodynamic coefficients and controls efficiencies.
Directory of Open Access Journals (Sweden)
Ming-Yuan Ren
2014-03-01
Full Text Available The nonideal factors of a liquid-suspended rotor micro-gyroscope include the gas-liquid two-phase flow voids, medium temperature and its dielectric relaxation, in which the role of the nonideal factors on the capacitor dielectric constant is altered, thereby affecting the capacitance detection precision of the micro-gyroscope. By comparing four different liquid media, the experimental results reveal the nonideal character of the capacitor dielectric constant. The 7# white oil is suitable for use as the liquid-suspended gyro cavity liquid medium.
Pasciuto, Ilaria; Ligorio, Gabriele; Bergamini, Elena; Vannozzi, Giuseppe; Sabatini, Angelo Maria; Cappozzo, Aurelio
2015-01-01
In human movement analysis, 3D body segment orientation can be obtained through the numerical integration of gyroscope signals. These signals, however, are affected by errors that, for the case of micro-electro-mechanical systems, are mainly due to: constant bias, scale factor, white noise, and bias instability. The aim of this study is to assess how the orientation estimation accuracy is affected by each of these disturbances, and whether it is influenced by the angular velocity magnitude and 3D distribution across the gyroscope axes. Reference angular velocity signals, either constant or representative of human walking, were corrupted with each of the four noise types within a simulation framework. The magnitude of the angular velocity affected the error in the orientation estimation due to each noise type, except for the white noise. Additionally, the error caused by the constant bias was also influenced by the angular velocity 3D distribution. As the orientation error depends not only on the noise itself but also on the signal it is applied to, different sensor placements could enhance or mitigate the error due to each disturbance, and special attention must be paid in providing and interpreting measures of accuracy for orientation estimation algorithms. PMID:26393606
Directory of Open Access Journals (Sweden)
Awang Hendrianto Pratomo
2015-07-01
Full Text Available MiRoSoT Robot movement is influenced by the speed control from right and left wheels. Wheels speed control on MiroSot robot is determined by parameter PID (Proportional Integral and Derevative value. PID value determined by robot position and angle. MiroSot robot movement is still not stable and can not move in accordance with the instruction have been made. Instability of the robot movement in the game is affected by friction wheels against the ground, friction gear and robot load. In this study, implemented a gyroscope and accelerometer sensors to stabilize robot movement. Based on both sensors are controlled by using a microcontroller ATmega64. Speed control system based on gyroscope and accelerometer sensor is obtained that the robot is able to face a certain angle more precisely. The accelerometer sensor is used as a parameter for the braking system, so the robot is able to move more stable without the loss of power from the motor during a reduction speed from the strategy control.
Using commodity accelerometers and gyroscopes to improve speed and accuracy of JanusVF
Hutson, Malcolm; Reiners, Dirk
2010-01-01
Several critical limitations exist in the currently available commercial tracking technologies for fully-enclosed virtual reality (VR) systems. While several 6DOF solutions can be adapted to work in fully-enclosed spaces, they still include elements of hardware that can interfere with the user's visual experience. JanusVF introduced a tracking solution for fully-enclosed VR displays that achieves comparable performance to available commercial solutions but without artifacts that can obscure the user's view. JanusVF employs a small, high-resolution camera that is worn on the user's head, but faces backwards. The VR rendering software draws specific fiducial markers with known size and absolute position inside the VR scene behind the user but in view of the camera. These fiducials are tracked by ARToolkitPlus and integrated by a single-constraint-at-a-time (SCAAT) filter to update the head pose. In this paper we investigate the addition of low-cost accelerometers and gyroscopes such as those in Nintendo Wii remotes, the Wii Motion Plus, and the Sony Sixaxis controller to improve the precision and accuracy of JanusVF. Several enthusiast projects have implemented these units as basic trackers or for gesture recognition, but none so far have created true 6DOF trackers using only the accelerometers and gyroscopes. Our original experiments were repeated after adding the low-cost inertial sensors, showing considerable improvements and noise reduction.
Markerless Augmented Reality Utilizing Gyroscope to Demonstrate the Position of Dewata Nawa Sanga
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I Wayan Andis Indrawan
2018-01-01
Full Text Available Dewata Nawa Sanga in Hinduism has an important role as the foundation of the religious concept implemented by Hindus in Bali, Indonesia. It has the meaning of nine deities or manifestations of Ida Sang Hyang Widhi Wasa (God Almighty that guard or control the nine wind direction. Dewata Nawa Sanga in terms of education in Bali has been learned by the elementary school students. However, in social life the concept of Dewata Nawa Sanga itself has not been attached and understood by all Balinese Hinduism yet. Based on the problem in social life, there is an idea to develop Markerless Augmented Reality Utilizing Gyroscope to Demonstrate the Position of Dewata Nawa Sanga. This application is designed to know, recognize, and understand the characteristics of Dewata Nawa Sanga using gyroscope. This sensor serves to fulfill the object of the deities in the coordinates to be determined. Furthermore, it serves to provide information about Dewata Nawa Sanga along with the innovative and informative 3D animation. The result of usefulness questionnaire of this application percentage value average is 88.4%. It can be concluded that AR Dewata Nawa Sanga is very useful and helpful for learners in exploring the Dewata Nawa Sanga position in a real-world environment. The result of usability and satisfaction questionnaire of this application percentage value average is 84.8%. It shows that the application is very useful for the participants to learn Dewata Nawa Sanga and very satisfied to use.
Error Correction of Measured Unstructured Road Profiles Based on Accelerometer and Gyroscope Data
Directory of Open Access Journals (Sweden)
Jinhua Han
2017-01-01
Full Text Available This paper describes a noncontact acquisition system composed of several time synchronized laser height sensors, accelerometers, gyroscope, and so forth in order to collect the road profiles of vehicle riding on the unstructured roads. A method of correcting road profiles based on the accelerometer and gyroscope data is proposed to eliminate the adverse impacts of vehicle vibration and attitudes change. Because the power spectral density (PSD of gyro attitudes concentrates in the low frequency band, a method called frequency division is presented to divide the road profiles into two parts: high frequency part and low frequency part. The vibration error of road profiles is corrected by displacement data obtained through two times integration of measured acceleration data. After building the mathematical model between gyro attitudes and road profiles, the gyro attitudes signals are separated from low frequency road profile by the method of sliding block overlap based on correlation analysis. The accuracy and limitations of the system have been analyzed, and its validity has been verified by implementing the system on wheeled equipment for road profiles’ measuring of vehicle testing ground. The paper offers an accurate and practical approach to obtaining unstructured road profiles for road simulation test.
Pasciuto, Ilaria; Ligorio, Gabriele; Bergamini, Elena; Vannozzi, Giuseppe; Sabatini, Angelo Maria; Cappozzo, Aurelio
2015-09-18
In human movement analysis, 3D body segment orientation can be obtained through the numerical integration of gyroscope signals. These signals, however, are affected by errors that, for the case of micro-electro-mechanical systems, are mainly due to: constant bias, scale factor, white noise, and bias instability. The aim of this study is to assess how the orientation estimation accuracy is affected by each of these disturbances, and whether it is influenced by the angular velocity magnitude and 3D distribution across the gyroscope axes. Reference angular velocity signals, either constant or representative of human walking, were corrupted with each of the four noise types within a simulation framework. The magnitude of the angular velocity affected the error in the orientation estimation due to each noise type, except for the white noise. Additionally, the error caused by the constant bias was also influenced by the angular velocity 3D distribution. As the orientation error depends not only on the noise itself but also on the signal it is applied to, different sensor placements could enhance or mitigate the error due to each disturbance, and special attention must be paid in providing and interpreting measures of accuracy for orientation estimation algorithms.
Modeling and Implementation of Multi-Position Non-Continuous Rotation Gyroscope North Finder
Directory of Open Access Journals (Sweden)
Jun Luo
2016-09-01
Full Text Available Even when the Global Positioning System (GPS signal is blocked, a rate gyroscope (gyro north finder is capable of providing the required azimuth reference information to a certain extent. In order to measure the azimuth between the observer and the north direction very accurately, we propose a multi-position non-continuous rotation gyro north finding scheme. Our new generalized mathematical model analyzes the elements that affect the azimuth measurement precision and can thus provide high precision azimuth reference information. Based on the gyro’s principle of detecting a projection of the earth rotation rate on its sensitive axis and the proposed north finding scheme, we are able to deduct an accurate mathematical model of the gyro outputs against azimuth with the gyro and shaft misalignments. Combining the gyro outputs model and the theory of propagation of uncertainty, some approaches to optimize north finding are provided, including reducing the gyro bias error, constraining the gyro random error, increasing the number of rotation points, improving rotation angle measurement precision, decreasing the gyro and the shaft misalignment angles. According them, a north finder setup is built and the azimuth uncertainty of 18” is obtained. This paper provides systematic theory for analyzing the details of the gyro north finder scheme from simulation to implementation. The proposed theory can guide both applied researchers in academia and advanced practitioners in industry for designing high precision robust north finder based on different types of rate gyroscopes.
Directory of Open Access Journals (Sweden)
Ilaria Pasciuto
2015-09-01
Full Text Available In human movement analysis, 3D body segment orientation can be obtained through the numerical integration of gyroscope signals. These signals, however, are affected by errors that, for the case of micro-electro-mechanical systems, are mainly due to: constant bias, scale factor, white noise, and bias instability. The aim of this study is to assess how the orientation estimation accuracy is affected by each of these disturbances, and whether it is influenced by the angular velocity magnitude and 3D distribution across the gyroscope axes. Reference angular velocity signals, either constant or representative of human walking, were corrupted with each of the four noise types within a simulation framework. The magnitude of the angular velocity affected the error in the orientation estimation due to each noise type, except for the white noise. Additionally, the error caused by the constant bias was also influenced by the angular velocity 3D distribution. As the orientation error depends not only on the noise itself but also on the signal it is applied to, different sensor placements could enhance or mitigate the error due to each disturbance, and special attention must be paid in providing and interpreting measures of accuracy for orientation estimation algorithms.
Use of Earth's magnetic field for mitigating gyroscope errors regardless of magnetic perturbation.
Afzal, Muhammad Haris; Renaudin, Valérie; Lachapelle, Gérard
2011-01-01
Most portable systems like smart-phones are equipped with low cost consumer grade sensors, making them useful as Pedestrian Navigation Systems (PNS). Measurements of these sensors are severely contaminated by errors caused due to instrumentation and environmental issues rendering the unaided navigation solution with these sensors of limited use. The overall navigation error budget associated with pedestrian navigation can be categorized into position/displacement errors and attitude/orientation errors. Most of the research is conducted for tackling and reducing the displacement errors, which either utilize Pedestrian Dead Reckoning (PDR) or special constraints like Zero velocity UPdaTes (ZUPT) and Zero Angular Rate Updates (ZARU). This article targets the orientation/attitude errors encountered in pedestrian navigation and develops a novel sensor fusion technique to utilize the Earth's magnetic field, even perturbed, for attitude and rate gyroscope error estimation in pedestrian navigation environments where it is assumed that Global Navigation Satellite System (GNSS) navigation is denied. As the Earth's magnetic field undergoes severe degradations in pedestrian navigation environments, a novel Quasi-Static magnetic Field (QSF) based attitude and angular rate error estimation technique is developed to effectively use magnetic measurements in highly perturbed environments. The QSF scheme is then used for generating the desired measurements for the proposed Extended Kalman Filter (EKF) based attitude estimator. Results indicate that the QSF measurements are capable of effectively estimating attitude and gyroscope errors, reducing the overall navigation error budget by over 80% in urban canyon environment.
Optimization of an Accelerometer and Gyroscope-Based Fall Detection Algorithm
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Quoc T. Huynh
2015-01-01
Full Text Available Falling is a common and significant cause of injury in elderly adults (>65 yrs old, often leading to disability and death. In the USA, one in three of the elderly suffers from fall injuries annually. This study’s purpose is to develop, optimize, and assess the efficacy of a falls detection algorithm based upon a wireless, wearable sensor system (WSS comprised of a 3-axis accelerometer and gyroscope. For this study, the WSS is placed at the chest center to collect real-time motion data of various simulated daily activities (i.e., walking, running, stepping, and falling. Tests were conducted on 36 human subjects with a total of 702 different movements collected in a laboratory setting. Half of the dataset was used for development of the fall detection algorithm including investigations of critical sensor thresholds and the remaining dataset was used for assessment of algorithm sensitivity and specificity. Experimental results show that the algorithm detects falls compared to other daily movements with a sensitivity and specificity of 96.3% and 96.2%, respectively. The addition of gyroscope information enhances sensitivity dramatically from results in the literature as angular velocity changes provide further delineation of a fall event from other activities that may also experience high acceleration peaks.
Observability analysis of a MEMS INS/GPS integration system with gyroscope G-sensitivity errors.
Fan, Chen; Hu, Xiaoping; He, Xiaofeng; Tang, Kanghua; Luo, Bing
2014-08-28
Gyroscopes based on micro-electromechanical system (MEMS) technology suffer in high-dynamic applications due to obvious g-sensitivity errors. These errors can induce large biases in the gyroscope, which can directly affect the accuracy of attitude estimation in the integration of the inertial navigation system (INS) and the Global Positioning System (GPS). The observability determines the existence of solutions for compensating them. In this paper, we investigate the observability of the INS/GPS system with consideration of the g-sensitivity errors. In terms of two types of g-sensitivity coefficients matrix, we add them as estimated states to the Kalman filter and analyze the observability of three or nine elements of the coefficient matrix respectively. A global observable condition of the system is presented and validated. Experimental results indicate that all the estimated states, which include position, velocity, attitude, gyro and accelerometer bias, and g-sensitivity coefficients, could be made observable by maneuvering based on the conditions. Compared with the integration system without compensation for the g-sensitivity errors, the attitude accuracy is raised obviously.
Observability Analysis of a MEMS INS/GPS Integration System with Gyroscope G-Sensitivity Errors
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Chen Fan
2014-08-01
Full Text Available Gyroscopes based on micro-electromechanical system (MEMS technology suffer in high-dynamic applications due to obvious g-sensitivity errors. These errors can induce large biases in the gyroscope, which can directly affect the accuracy of attitude estimation in the integration of the inertial navigation system (INS and the Global Positioning System (GPS. The observability determines the existence of solutions for compensating them. In this paper, we investigate the observability of the INS/GPS system with consideration of the g-sensitivity errors. In terms of two types of g-sensitivity coefficients matrix, we add them as estimated states to the Kalman filter and analyze the observability of three or nine elements of the coefficient matrix respectively. A global observable condition of the system is presented and validated. Experimental results indicate that all the estimated states, which include position, velocity, attitude, gyro and accelerometer bias, and g-sensitivity coefficients, could be made observable by maneuvering based on the conditions. Compared with the integration system without compensation for the g-sensitivity errors, the attitude accuracy is raised obviously.
Directory of Open Access Journals (Sweden)
Yang Gao
2017-04-01
Full Text Available This paper presents the design and application of a lever coupling mechanism to improve the shock resistance of a dual-mass silicon micro-gyroscope with drive mode coupled along the driving direction without sacrificing the mechanical sensitivity. Firstly, the mechanical sensitivity and the shock response of the micro-gyroscope are theoretically analyzed. In the mechanical design, a novel lever coupling mechanism is proposed to change the modal order and to improve the frequency separation. The micro-gyroscope with the lever coupling mechanism optimizes the drive mode order, increasing the in-phase mode frequency to be much larger than the anti-phase one. Shock analysis results show that the micro-gyroscope structure with the designed lever coupling mechanism can notably reduce the magnitudes of the shock response and cut down the stress produced in the shock process compared with the traditional elastic coupled one. Simulations reveal that the shock resistance along the drive direction is greatly increased. Consequently, the lever coupling mechanism can change the gyroscope’s modal order and improve the frequency separation by structurally offering a higher stiffness difference ratio. The shock resistance along the driving direction is tremendously enhanced without loss of the mechanical sensitivity.
Xing, Haifeng; Hou, Bo; Lin, Zhihui; Guo, Meifeng
2017-10-13
MEMS (Micro Electro Mechanical System) gyroscopes have been widely applied to various fields, but MEMS gyroscope random drift has nonlinear and non-stationary characteristics. It has attracted much attention to model and compensate the random drift because it can improve the precision of inertial devices. This paper has proposed to use wavelet filtering to reduce noise in the original data of MEMS gyroscopes, then reconstruct the random drift data with PSR (phase space reconstruction), and establish the model for the reconstructed data by LSSVM (least squares support vector machine), of which the parameters were optimized using CPSO (chaotic particle swarm optimization). Comparing the effect of modeling the MEMS gyroscope random drift with BP-ANN (back propagation artificial neural network) and the proposed method, the results showed that the latter had a better prediction accuracy. Using the compensation of three groups of MEMS gyroscope random drift data, the standard deviation of three groups of experimental data dropped from 0.00354°/s, 0.00412°/s, and 0.00328°/s to 0.00065°/s, 0.00072°/s and 0.00061°/s, respectively, which demonstrated that the proposed method can reduce the influence of MEMS gyroscope random drift and verified the effectiveness of this method for modeling MEMS gyroscope random drift.
International Nuclear Information System (INIS)
Farivar, Faezeh; Aliyari Shoorehdeli, Mahdi; Nekoui, Mohammad Ali; Teshnehlab, Mohammad
2012-01-01
Highlights: ► A systematic procedure for GPS of unknown heavy chaotic gyroscope systems. ► Proposed methods are based on Lyapunov stability theory. ► Without calculating Lyapunov exponents and Eigen values of the Jacobian matrix. ► Capable to extend for a variety of chaotic systems. ► Useful for practical applications in the future. - Abstract: This paper proposes the chaos control and the generalized projective synchronization methods for heavy symmetric gyroscope systems via Gaussian radial basis adaptive variable structure control. Because of the nonlinear terms of the gyroscope system, the system exhibits chaotic motions. Occasionally, the extreme sensitivity to initial states in a system operating in chaotic mode can be very destructive to the system because of unpredictable behavior. In order to improve the performance of a dynamic system or avoid the chaotic phenomena, it is necessary to control a chaotic system with a periodic motion beneficial for working with a particular condition. As chaotic signals are usually broadband and noise like, synchronized chaotic systems can be used as cipher generators for secure communication. This paper presents chaos synchronization of two identical chaotic motions of symmetric gyroscopes. In this paper, the switching surfaces are adopted to ensure the stability of the error dynamics in variable structure control. Using the neural variable structure control technique, control laws are established which guarantees the chaos control and the generalized projective synchronization of unknown gyroscope systems. In the neural variable structure control, Gaussian radial basis functions are utilized to on-line estimate the system dynamic functions. Also, the adaptation laws of the on-line estimator are derived in the sense of Lyapunov function. Thus, the unknown gyro systems can be guaranteed to be asymptotically stable. Also, the proposed method can achieve the control objectives. Numerical simulations are presented to
Adaptive Sliding Mode Control of MEMS Gyroscope Based on Neural Network Approximation
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Yuzheng Yang
2014-01-01
Full Text Available An adaptive sliding controller using radial basis function (RBF network to approximate the unknown system dynamics microelectromechanical systems (MEMS gyroscope sensor is proposed. Neural controller is proposed to approximate the unknown system model and sliding controller is employed to eliminate the approximation error and attenuate the model uncertainties and external disturbances. Online neural network (NN weight tuning algorithms, including correction terms, are designed based on Lyapunov stability theory, which can guarantee bounded tracking errors as well as bounded NN weights. The tracking error bound can be made arbitrarily small by increasing a certain feedback gain. Numerical simulation for a MEMS angular velocity sensor is investigated to verify the effectiveness of the proposed adaptive neural control scheme and demonstrate the satisfactory tracking performance and robustness.
Murray, Matthew J.; Ogden, Hannah M.; Mullin, Amy S.
2017-10-01
An optical centrifuge is used to generate an ensemble of CO2 super rotors with oriented angular momentum. The collision dynamics and energy transfer behavior of the super rotor molecules are investigated using high-resolution transient IR absorption spectroscopy. New multipass IR detection provides improved sensitivity to perform polarization-dependent transient studies for rotational states with 76 ≤ J ≤ 100. Polarization-dependent measurements show that the collision-induced kinetic energy release is spatially anisotropic and results from both near-resonant energy transfer between super rotor molecules and non-resonant energy transfer between super rotors and thermal molecules. J-dependent studies show that the extent and duration of the orientational anisotropy increase with rotational angular momentum. The super rotors exhibit behavior akin to molecular gyroscopes, wherein molecules with larger amounts of angular momentum are less likely to change their angular momentum orientation through collisions.
Directory of Open Access Journals (Sweden)
Yuan Ren
2014-01-01
Full Text Available For magnetically suspended rigid rotors (MSRs with significant gyroscopic effects, phase lag of the control channel is the main factor influencing the system nutation stability and decoupling performance. At first, this paper proves that the phase lag of the cross channel instead of the decentralized channel is often the main factor influencing the system nutation stability at high speeds. Then a modified cross feedback control strategy based on the phase compensation of cross channel is proposed to improve the stability and decoupling performances. The common issues associated with the traditional control methods have been successfully resolved by this method. Analysis, simulation, and experimental results are presented to demonstrate the feasibility and superiority of the proposed control method.
Vernier effect-based multiplication of the Sagnac beating frequency in ring laser gyroscope sensors
Adib, George A.; Sabry, Yasser M.; Khalil, Diaa
2018-02-01
A multiplication method of the Sagnac effect scale factor in ring laser gyroscopes is presented based on the Vernier effect of a dual-coupler passive ring resonator coupled to the active ring. The multiplication occurs when the two rings have comparable lengths or integer multiples and their scale factors have opposite signs. In this case, and when the rings have similar areas, the scale factor is multiplied by ratio of their length to their length difference. The scale factor of the presented configuration is derived analytically and the lock-in effect is analyzed. The principle is demonstrated using optical fiber rings and semiconductor optical amplifier as gain medium. A scale factor multiplication by about 175 is experimentally measured, demonstrating larger than two orders of magnitude enhancement in the Sagnac effect scale factor for the first time in literature, up to the authors' knowledge.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Gyro's fault diagnosis plays a critical role in inertia navigation systems for higher reliability and precision. A new fault diagnosis strategy based on the statistical parameter analysis (SPA) and support vector machine(SVM) classification model was proposed for dynamically tuned gyroscopes (DTG). The SPA, a kind of time domain analysis approach, was introduced to compute a set of statistical parameters of vibration signal as the state features of DTG, with which the SVM model, a novel learning machine based on statistical learning theory (SLT), was applied and constructed to train and identify the working state of DTG. The experimental results verify that the proposed diagnostic strategy can simply and effectively extract the state features of DTG, and it outperforms the radial-basis function (RBF) neural network based diagnostic method and can more reliably and accurately diagnose the working state of DTG.
Temperature Dependence of Faraday Effect-Induced Bias Error in a Fiber Optic Gyroscope.
Li, Xuyou; Liu, Pan; Guang, Xingxing; Xu, Zhenlong; Guan, Lianwu; Li, Guangchun
2017-09-07
Improving the performance of interferometric fiber optic gyroscope (IFOG) in harsh environments, such as magnetic field and temperature field variation, is necessary for its practical applications. This paper presents an investigation of Faraday effect-induced bias error of IFOG under varying temperature. Jones matrix method is utilized to formulize the temperature dependence of Faraday effect-induced bias error. Theoretical results show that the Faraday effect-induced bias error changes with the temperature in the non-skeleton polarization maintaining (PM) fiber coil. This phenomenon is caused by the temperature dependence of linear birefringence and Verdet constant of PM fiber. Particularly, Faraday effect-induced bias errors of two polarizations always have opposite signs that can be compensated optically regardless of the changes of the temperature. Two experiments with a 1000 m non-skeleton PM fiber coil are performed, and the experimental results support these theoretical predictions. This study is promising for improving the bias stability of IFOG.
A Novel Temperature Compensation Method for a MEMS Gyroscope Oriented on a Periphery Circuit
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Huiliang Cao
2013-09-01
Full Text Available This paper investigates temperature compensation methods used for the scale factor and bias of the MEMS gyroscope within the temperature range from − 40°C to 60°C. The structure and periphery monitor circuit are introduced. Then the determinant elements of the MEMS gyroscope's scale factor are analysed and the results indicate that scale factor is directly proportional to drive amplitude and sense loop gain and is inversely proportional to the frequency gap between two modes. After that, the compensation methods are proposed, the thermal resistor's positive temperature coefficient (tempco is utilized to calibrate the scale factor's tempco through regulating the drive mode amplitude and the sense loop gain, and each method is applied respectively and the results are contrasted. The test results of the two specimens express that the most effective compensation method could decrease the scale factor's tempco from 693ppm/°C (640ppm/°C to 250ppm/°C (257ppm/°C, improving it by 63.9% (59.8%. Finally, a method of declining bias's tempco is investigated and implemented after scale factor compensation. A summator with a thermal resistor is utilized at the output level and decreases the bias's tempco from 103.89°/h/°C (100.78°/h/°C to 9.70°/h/°C (12°/h/°C improving it by 90.7% (88%. Repeat tests are performed based on two specimens to prove the repeatability and reproducibility of the methods.
Rosas-Cholula, Gerardo; Ramirez-Cortes, Juan Manuel; Alarcon-Aquino, Vicente; Gomez-Gil, Pilar; Rangel-Magdaleno, Jose de Jesus; Reyes-Garcia, Carlos
2013-08-14
This paper presents a project on the development of a cursor control emulating the typical operations of a computer-mouse, using gyroscope and eye-blinking electromyographic signals which are obtained through a commercial 16-electrode wireless headset, recently released by Emotiv. The cursor position is controlled using information from a gyroscope included in the headset. The clicks are generated through the user's blinking with an adequate detection procedure based on the spectral-like technique called Empirical Mode Decomposition (EMD). EMD is proposed as a simple and quick computational tool, yet effective, aimed to artifact reduction from head movements as well as a method to detect blinking signals for mouse control. Kalman filter is used as state estimator for mouse position control and jitter removal. The detection rate obtained in average was 94.9%. Experimental setup and some obtained results are presented.
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Carlos Reyes-Garcia
2013-08-01
Full Text Available This paper presents a project on the development of a cursor control emulating the typical operations of a computer-mouse, using gyroscope and eye-blinking electromyographic signals which are obtained through a commercial 16-electrode wireless headset, recently released by Emotiv. The cursor position is controlled using information from a gyroscope included in the headset. The clicks are generated through the user’s blinking with an adequate detection procedure based on the spectral-like technique called Empirical Mode Decomposition (EMD. EMD is proposed as a simple and quick computational tool, yet effective, aimed to artifact reduction from head movements as well as a method to detect blinking signals for mouse control. Kalman filter is used as state estimator for mouse position control and jitter removal. The detection rate obtained in average was 94.9%. Experimental setup and some obtained results are presented.
1982-03-01
Gyroscopes .... ....... 2 1.2 Sagnac’s Interferometer ....... ........ . . 4 1.3 Harress ’ Ring Interferometer ....... ...... 5 1.4 Michelson & Gale...graduate student, Harress , performed an experi- ment in which he attempted to measure the dispersion properties of glass. Figure 1.3 shows Harress ...8217 experiment. The results from his experiment did not agree-with data obtained from other methods, and Harress did not live long enough to find the discrepancy
Joaquim José Silva Faria Oliveira
2014-01-01
Currently it only is possible to obtain information about a tap on the smartphone's screen using the touch sensor. The goal of this project is to complement the information given by the smartphones touch screen with information given by the accelerometer and gyroscope and this way to extend the smartphone's touch capabilities with data such as tap strength, smartphone's holding position while taping (if it is on the users hands or laying on a hard surface) or which finger the touch was perfor...
Hinson, Brian T; Morgansen, Kristi A
2015-10-06
The wings of the hawkmoth Manduca sexta are lined with mechanoreceptors called campaniform sensilla that encode wing deformations. During flight, the wings deform in response to a variety of stimuli, including inertial-elastic loads due to the wing flapping motion, aerodynamic loads, and exogenous inertial loads transmitted by disturbances. Because the wings are actuated, flexible structures, the strain-sensitive campaniform sensilla are capable of detecting inertial rotations and accelerations, allowing the wings to serve not only as a primary actuator, but also as a gyroscopic sensor for flight control. We study the gyroscopic sensing of the hawkmoth wings from a control theoretic perspective. Through the development of a low-order model of flexible wing flapping dynamics, and the use of nonlinear observability analysis, we show that the rotational acceleration inherent in wing flapping enables the wings to serve as gyroscopic sensors. We compute a measure of sensor fitness as a function of sensor location and directional sensitivity by using the simulation-based empirical observability Gramian. Our results indicate that gyroscopic information is encoded primarily through shear strain due to wing twisting, where inertial rotations cause detectable changes in pronation and supination timing and magnitude. We solve an observability-based optimal sensor placement problem to find the optimal configuration of strain sensor locations and directional sensitivities for detecting inertial rotations. The optimal sensor configuration shows parallels to the campaniform sensilla found on hawkmoth wings, with clusters of sensors near the wing root and wing tip. The optimal spatial distribution of strain directional sensitivity provides a hypothesis for how heterogeneity of campaniform sensilla may be distributed.
Abedi, Maryam; Jin, Tian; Sun, Kewen
2015-06-17
In this paper, a gyroscopic mounting method for crystal oscillators to reduce the impact of dynamic loads on their output stability has been proposed. In order to prove the efficiency of this mounting approach, each dynamic load-induced instability has been analyzed in detail. A statistical study has been performed on the elevation angle of the g-sensitivity vector of Stress Compensated-cut (SC-cut) crystals. The analysis results show that the proposed gyroscopic mounting method gives good performance for host vehicle attitude changes. A phase noise improvement of 27 dB maximum and 5.7 dB on average can be achieved in the case of steady state loads, while under sinusoidal vibration conditions, the maximum and average phase noise improvement are as high as 24 dB and 7.5 dB respectively. With this gyroscopic mounting method, random vibration-induced phase noise instability is reduced 30 dB maximum and 8.7 dB on average. Good effects are apparent for crystal g-sensitivity vectors with low elevation angle φ and azimuthal angle β. under highly dynamic conditions, indicating the probability that crystal oscillator instability will be significantly reduced by using the proposed mounting approach.
From Gyroscopic to Thermal Motion: A Crossover in the Dynamics of Molecular Superrotors
Milner, A. A.; Korobenko, A.; Rezaiezadeh, K.; Milner, V.
2015-07-01
Localized heating of a gas by intense laser pulses leads to interesting acoustic, hydrodynamic, and optical effects with numerous applications in science and technology, including controlled wave guiding and remote atmosphere sensing. Rotational excitation of molecules can serve as the energy source for raising the gas temperature. Here, we study the dynamics of energy transfer from the molecular rotation to heat. By optically imaging a cloud of molecular superrotors, created with an optical centrifuge, we experimentally identify two separate and qualitatively different stages of its evolution. The first nonequilibrium "gyroscopic" stage is characterized by the modified optical properties of the centrifuged gas—its refractive index and optical birefringence, owing to the ultrafast directional molecular rotation, which survives tens of collisions. The loss of rotational directionality is found to overlap with the release of rotational energy to heat, which triggers the second stage of thermal expansion. The crossover between anisotropic rotational and isotropic thermal regimes is in agreement with recent theoretical predictions and our hydrodynamic calculations.
Limit of detection of a fiber optics gyroscope using a super luminescent radiation source
International Nuclear Information System (INIS)
Sandoval R, G.E.; Nikolaev, V.A.
2003-01-01
The main objective of this work is to establish the dependence of characteristics of the fiber optics gyroscope (FOG) with respect to the parameters of the super luminescent emission source based on doped optical fiber with rare earth elements (Super luminescent Fiber Source, SFS), argument the pumping rate election of the SFS to obtain characteristics limits of the FOG sensibility. By using this type of emission source in the FOG is recommend to use the rate when the direction of the pumping signal coincide with the super luminescent signal. The most results are the proposition and argumentation of the SFS election as emission source to be use in the FOG of the phase type. Such a decision allow to increase the characteristics of the FOG sensibility in comparison with the use of luminescent source of semiconductors emission which are extensively used in the present time. The use of emission source of the SFS type allow to come closer to the threshold of the obtained sensibility limit (detection limit) which is determined with the shot noise. (Author)
Analysis and Optimization of Dynamic Measurement Precision of Fiber Optic Gyroscope
Directory of Open Access Journals (Sweden)
Hui Li
2013-01-01
Full Text Available In order to improve the dynamic performance of high precision interferometer fiber optic gyroscope (IFOG, the influencing factors of the fast response characteristics are analyzed based on a proposed assistant design setup, and a high dynamic detection method is proposed to suppress the adverse effects of the key influencing factors. The assistant design platform is built by using the virtual instrument technology for IFOG, which can monitor the closed-loop state variables in real time for analyzing the influence of both the optical components and detection circuit on the dynamic performance of IFOG. The analysis results indicate that nonlinearity of optical Sagnac effect, optical parameter uncertainty, dynamic characteristics of internal modules and time delay of signal detection circuit are the major causes of dynamic performance deterioration, which can induce potential system instability in practical control systems. By taking all these factors into consideration, we design a robust control algorithm to realize the high dynamic closed-loop detection of IFOG. Finally, experiments show that the improved 0.01 deg/h high precision IFOG with the proposed control algorithm can achieve fast tracking and good dynamic measurement precision.
Siregar, B.; Andayani, U.; Bahri, R. P.; Seniman; Fahmi, F.
2018-03-01
Most of the elderly people is experiencing a decrease in physical quality, especially the weakness in the legs. This will cause elderly easy to fall and can have a serious impact on their health if not getting help very quickly. It is, therefore, necessary to take immediate action against the falling cases experienced by the elderly. One such action is by developing supervision and detecting of falling movements in real-time, which is then the connection to a member of the family. In this research, we used Arduino Uno as a microcontroller, sensor accelerometer, and gyroscope that serves to measure falling movement of the elderly person and supported by GPS technology Ublox Neo 6M to provide information about coordinates. The result was the high accuracy of delivering notification data to server and accuracy of data delivery to family notification equal to 93,75%. The system successfully detects the direction of falling: forward, backward, left or right and able to distinguish between unintentional falling and conscious falling like a bow or prostrate position.
Directory of Open Access Journals (Sweden)
D. S. Gromov
2014-03-01
Full Text Available It is known, that temperature perturbations and thermal modes have significant influence on the accuracy of a fiber-optical gyroscope. Nowadays, thermal perturbations are among the main problems in the field of navigation accuracy. Review of existing methods for decrease of temperature influences on the accuracy of a strapdown inertial navigation system with fiberoptical gyros showed, that the usage of constructive and compensation methods only is insufficient and, therefore, thermostabilization is required. Reversible thermostabilization system is offered, its main executive elements are thermoelectric modules (Peltier’s modules, heat transfer from which is provided by heatsinks at work surfaces of modules. This variant of thermostabilization maintenance is considered; Peltier’s modules and temperature sensors for the system are chosen. Parameters of heatsinks for heat transfer intensification are calculated. Fans for necessary air circulation in the device are chosen and thickness of thermal isolation is calculated. Calculations of thermal modes of navigation system with thermostabilization are made in modern software Autodesk Simulation CFD. Comparison of results for present and previous researches and calculations shows essential decrease in gradients of temperature on gyro surfaces and better uniformity of temperature field in the whole device. Conclusions about efficiency of the given method usage in view of accuracy improvement of navigation system are made. Thermostabilization provision of a strapdown inertial navigation system with fiberoptical gyros is proved. Thermostabilization application in combination with compensational methods can reach a necessary accuracy of navigation system.
AMA- and RWE- Based Adaptive Kalman Filter for Denoising Fiber Optic Gyroscope Drift Signal.
Yang, Gongliu; Liu, Yuanyuan; Li, Ming; Song, Shunguang
2015-10-23
An improved double-factor adaptive Kalman filter called AMA-RWE-DFAKF is proposed to denoise fiber optic gyroscope (FOG) drift signal in both static and dynamic conditions. The first factor is Kalman gain updated by random weighting estimation (RWE) of the covariance matrix of innovation sequence at any time to ensure the lowest noise level of output, but the inertia of KF response increases in dynamic condition. To decrease the inertia, the second factor is the covariance matrix of predicted state vector adjusted by RWE only when discontinuities are detected by adaptive moving average (AMA).The AMA-RWE-DFAKF is applied for denoising FOG static and dynamic signals, its performance is compared with conventional KF (CKF), RWE-based adaptive KF with gain correction (RWE-AKFG), AMA- and RWE- based dual mode adaptive KF (AMA-RWE-DMAKF). Results of Allan variance on static signal and root mean square error (RMSE) on dynamic signal show that this proposed algorithm outperforms all the considered methods in denoising FOG signal.
Robust trajectory tracking control of a dual-arm space robot actuated by control moment gyroscopes
Jia, Yinghong; Misra, Arun K.
2017-08-01
It is a new design concept to employ control moment gyroscopes (CMGs) as reactionless actuators for space robots. Such actuation has several noticeable advantages such as weak dynamical coupling and low power consumption over traditional joint motor actuation. This paper presents a robust control law for a CMG-actuated space robot in presence of system uncertainties and closed-chain constraints. The control objective is to make the manipulation variables to track the desired trajectories, and reduce the possibility of CMG saturation simultaneously. A reduced-order dynamical equation in terms of independent motion variables is derived using Kane's equations. Desired trajectories of the independent motion variables are derived by minimum-norm trajectory planning algorithm, and an adaptive sliding mode controller with improved adaptation laws is proposed to drive the independent motion variables tracking the desired trajectories. Uniformly ultimate boundedness of the closed loop system is proven using Lyapunov method. The redundancy of the full-order actual control torques is utilized to generate a null torque vector which reduces the possibility of CMG angular momentum saturation while producing no effect on the reduced-order control input. Simulation results demonstrate the effectiveness of the proposed algorithms and the advantage of weak dynamical coupling of the CMG-actuated system.
Vibration-Induced Errors in MEMS Tuning Fork Gyroscopes with Imbalance.
Fang, Xiang; Dong, Linxi; Zhao, Wen-Sheng; Yan, Haixia; Teh, Kwok Siong; Wang, Gaofeng
2018-05-29
This paper discusses the vibration-induced error in non-ideal MEMS tuning fork gyroscopes (TFGs). Ideal TFGs which are thought to be immune to vibrations do not exist, and imbalance between two gyros of TFGs is an inevitable phenomenon. Three types of fabrication imperfections (i.e., stiffness imbalance, mass imbalance, and damping imbalance) are studied, considering different imbalance radios. We focus on the coupling types of two gyros of TFGs in both drive and sense directions, and the vibration sensitivities of four TFG designs with imbalance are simulated and compared. It is found that non-ideal TFGs with two gyros coupled both in drive and sense directions (type CC TFGs) are the most insensitive to vibrations with frequencies close to the TFG operating frequencies. However, sense-axis vibrations with in-phase resonant frequencies of a coupled gyros system result in severe error outputs to TFGs with two gyros coupled in the sense direction, which is mainly attributed to the sense capacitance nonlinearity. With increasing stiffness coupled ratio of the coupled gyros system, the sensitivity to vibrations with operating frequencies is cut down, yet sensitivity to vibrations with in-phase frequencies is amplified.
Two Novel Measurements for the Drive-Mode Resonant Frequency of a Micromachined Vibratory Gyroscope
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Ancheng Wang
2013-11-01
Full Text Available To investigate the drive-mode resonance frequency of a micromachined vibratory gyroscope (MVG, one needs to measure it accurately and efficiently. The conventional approach to measure the resonant frequency is by performing a sweep frequency test and spectrum analysis. The method is time-consuming and inconvenient because of the requirements of many test points, a lot of data storage and off-line analyses. In this paper, we propose two novel measurement methods, the search method and track method, respectively. The former is based on the magnitude-frequency characteristics of the drive mode, utilizing a one-dimensional search technique. The latter is based on the phase-frequency characteristics, applying a feedback control loop. Their performances in precision, noise resistivity and efficiency are analyzed through detailed simulations. A test system is implemented based on a field programmable gate array (FPGA and experiments are carried out. By comparing with the common approach, feasibility and superiorities of the proposed methods are validated. In particular, significant efficiency improvements are achieved whereby the conventional frequency method consumes nearly 5,000 s to finish a measurement, while only 5 s is needed for the track method and 1 s for the search method.
Key Processes of Silicon-On-Glass MEMS Fabrication Technology for Gyroscope Application.
Ma, Zhibo; Wang, Yinan; Shen, Qiang; Zhang, Han; Guo, Xuetao
2018-04-17
MEMS fabrication that is based on the silicon-on-glass (SOG) process requires many steps, including patterning, anodic bonding, deep reactive ion etching (DRIE), and chemical mechanical polishing (CMP). The effects of the process parameters of CMP and DRIE are investigated in this study. The process parameters of CMP, such as abrasive size, load pressure, and pH value of SF1 solution are examined to optimize the total thickness variation in the structure and the surface quality. The ratio of etching and passivation cycle time and the process pressure are also adjusted to achieve satisfactory performance during DRIE. The process is optimized to avoid neither the notching nor lag effects on the fabricated silicon structures. For demonstrating the capability of the modified CMP and DRIE processes, a z-axis micro gyroscope is fabricated that is based on the SOG process. Initial test results show that the average surface roughness of silicon is below 1.13 nm and the thickness of the silicon is measured to be 50 μm. All of the structures are well defined without the footing effect by the use of the modified DRIE process. The initial performance test results of the resonant frequency for the drive and sense modes are 4.048 and 4.076 kHz, respectively. The demands for this kind of SOG MEMS device can be fulfilled using the optimized process.
Directory of Open Access Journals (Sweden)
Tao Li
2016-03-01
Full Text Available The derivation of a conventional error model for the miniature gyroscope-based measurement while drilling (MGWD system is based on the assumption that the errors of attitude are small enough so that the direction cosine matrix (DCM can be approximated or simplified by the errors of small-angle attitude. However, the simplification of the DCM would introduce errors to the navigation solutions of the MGWD system if the initial alignment cannot provide precise attitude, especially for the low-cost microelectromechanical system (MEMS sensors operated in harsh multilateral horizontal downhole drilling environments. This paper proposes a novel nonlinear error model (NNEM by the introduction of the error of DCM, and the NNEM can reduce the propagated errors under large-angle attitude error conditions. The zero velocity and zero position are the reference points and the innovations in the states estimation of particle filter (PF and Kalman filter (KF. The experimental results illustrate that the performance of PF is better than KF and the PF with NNEM can effectively restrain the errors of system states, especially for the azimuth, velocity, and height in the quasi-stationary condition.
Li, Tao; Yuan, Gannan; Li, Wang
2016-03-15
The derivation of a conventional error model for the miniature gyroscope-based measurement while drilling (MGWD) system is based on the assumption that the errors of attitude are small enough so that the direction cosine matrix (DCM) can be approximated or simplified by the errors of small-angle attitude. However, the simplification of the DCM would introduce errors to the navigation solutions of the MGWD system if the initial alignment cannot provide precise attitude, especially for the low-cost microelectromechanical system (MEMS) sensors operated in harsh multilateral horizontal downhole drilling environments. This paper proposes a novel nonlinear error model (NNEM) by the introduction of the error of DCM, and the NNEM can reduce the propagated errors under large-angle attitude error conditions. The zero velocity and zero position are the reference points and the innovations in the states estimation of particle filter (PF) and Kalman filter (KF). The experimental results illustrate that the performance of PF is better than KF and the PF with NNEM can effectively restrain the errors of system states, especially for the azimuth, velocity, and height in the quasi-stationary condition.
Limit of detection of a fiber optics gyroscope using a super luminescent radiation source
Sandoval, G E
2003-01-01
The main objective of this work is to establish the dependence of characteristics of the fiber optics gyroscope (FOG) with respect to the parameters of the super luminescent emission source based on doped optical fiber with rare earth elements (Super luminescent Fiber Source, SFS), argument the pumping rate election of the SFS to obtain characteristics limits of the FOG sensibility. By using this type of emission source in the FOG is recommend to use the rate when the direction of the pumping signal coincide with the super luminescent signal. The most results are the proposition and argumentation of the SFS election as emission source to be use in the FOG of the phase type. Such a decision allow to increase the characteristics of the FOG sensibility in comparison with the use of luminescent source of semiconductors emission which are extensively used in the present time. The use of emission source of the SFS type allow to come closer to the threshold of the obtained sensibility limit (detection limit) which i...
Optimization and Experimentation of Dual-Mass MEMS Gyroscope Quadrature Error Correction Methods.
Cao, Huiliang; Li, Hongsheng; Kou, Zhiwei; Shi, Yunbo; Tang, Jun; Ma, Zongmin; Shen, Chong; Liu, Jun
2016-01-07
This paper focuses on an optimal quadrature error correction method for the dual-mass MEMS gyroscope, in order to reduce the long term bias drift. It is known that the coupling stiffness and demodulation error are important elements causing bias drift. The coupling stiffness in dual-mass structures is analyzed. The experiment proves that the left and right masses' quadrature errors are different, and the quadrature correction system should be arranged independently. The process leading to quadrature error is proposed, and the Charge Injecting Correction (CIC), Quadrature Force Correction (QFC) and Coupling Stiffness Correction (CSC) methods are introduced. The correction objects of these three methods are the quadrature error signal, force and the coupling stiffness, respectively. The three methods are investigated through control theory analysis, model simulation and circuit experiments, and the results support the theoretical analysis. The bias stability results based on CIC, QFC and CSC are 48 °/h, 9.9 °/h and 3.7 °/h, respectively, and this value is 38 °/h before quadrature error correction. The CSC method is proved to be the better method for quadrature correction, and it improves the Angle Random Walking (ARW) value, increasing it from 0.66 °/√h to 0.21 °/√h. The CSC system general test results show that it works well across the full temperature range, and the bias stabilities of the six groups' output data are 3.8 °/h, 3.6 °/h, 3.4 °/h, 3.1 °/h, 3.0 °/h and 4.2 °/h, respectively, which proves the system has excellent repeatability.
Multidimensional gray-wavelet processing in interferometric fiber-optic gyroscopes
International Nuclear Information System (INIS)
Yang, Yi; Wang, Zinan; Peng, Chao; Li, Zhengbin
2013-01-01
A multidimensional signal processing method for a single interferometric fiber-optic gyroscope (IFOG) is proposed, to the best of our knowledge, for the first time. The proposed method, based on a novel IFOG structure with quadrature demodulation, combines a multidimensional gray model (GM) and a wavelet compression technique for noise suppression and sensitivity enhancement. In the IFOG, two series of measured rotation rates are obtained simultaneously: an in-phase component and a quadrature component. Together with the traditionally measured rate, the three measured rates are processed by the combined gray-wavelet method. Simulations show that the intensity noise and non-reciprocal phase fluctuations are effectively suppressed by this method. Experimental comparisons with a one-dimensional GM(1, 1) model show that the proposed three-dimensional method achieves much better denoising performance. This advantage is validated by the Allan variance analysis: in a low-SNR (signal-to-noise ratio) experiment, our method reduces the angle random walk (ARW) and the bias instability (BI) from 1 × 10 −2 deg h −1/2 and 3 × 10 −2 deg h −1 to 1 × 10 −3 deg h −1/2 and 3 × 10 −3 deg h −1 , respectively; in a high-SNR experiment, our method reduces the ARW and the BI from 9 × 10 −4 deg h −1/2 and 5 × 10 −3 deg h −1 to 4 × 10 −4 deg h −1/2 and 3 × 10 −3 deg h −1 , respectively. Further, our method increases the dimension of the state-of-the-art IFOG technique from one to three, thus obtaining higher IFOG sensitivity and stability by exploiting the increase in available information. (paper)
Multidimensional gray-wavelet processing in interferometric fiber-optic gyroscopes
Yang, Yi; Wang, Zinan; Peng, Chao; Li, Zhengbin
2013-11-01
A multidimensional signal processing method for a single interferometric fiber-optic gyroscope (IFOG) is proposed, to the best of our knowledge, for the first time. The proposed method, based on a novel IFOG structure with quadrature demodulation, combines a multidimensional gray model (GM) and a wavelet compression technique for noise suppression and sensitivity enhancement. In the IFOG, two series of measured rotation rates are obtained simultaneously: an in-phase component and a quadrature component. Together with the traditionally measured rate, the three measured rates are processed by the combined gray-wavelet method. Simulations show that the intensity noise and non-reciprocal phase fluctuations are effectively suppressed by this method. Experimental comparisons with a one-dimensional GM(1, 1) model show that the proposed three-dimensional method achieves much better denoising performance. This advantage is validated by the Allan variance analysis: in a low-SNR (signal-to-noise ratio) experiment, our method reduces the angle random walk (ARW) and the bias instability (BI) from 1 × 10-2 deg h-1/2 and 3 × 10-2 deg h-1 to 1 × 10-3 deg h-1/2 and 3 × 10-3 deg h-1, respectively; in a high-SNR experiment, our method reduces the ARW and the BI from 9 × 10-4 deg h-1/2 and 5 × 10-3 deg h-1 to 4 × 10-4 deg h-1/2 and 3 × 10-3 deg h-1, respectively. Further, our method increases the dimension of the state-of-the-art IFOG technique from one to three, thus obtaining higher IFOG sensitivity and stability by exploiting the increase in available information.
Energy Technology Data Exchange (ETDEWEB)
Stoll, J.B. [BGR, Hannover (Germany); Leven, M.; Steveling, E. [Inst. fuer Geophysik, Goettingen (Germany)
2003-07-01
A fibre optical gyroscope was installed in a borehole magnetometer in the framework of a DFG-funded pilot project carried out in co-operation with the Institute of Geophysics of Goettingen University. The measuring system was used in an ocean log in the NW Pacific for measuring the remnant section of the magnetic field of the strongly magnetic ocean crust and its direction. the system is completely independent of the magnetic field, which is not required as an orientation aid. Further applications are envisaged in online measuring of borehole or cavern geometries and subsequent orientation of borehole wall images using imaging procedures like FMS, FMI, or borehole televiewer. [German] Um die Drehwinkel eines im Raum rotierenden Messsystems zu erfassen, gibt es verschiedene Messtechniken, mit denen die Raumlage eines Messsystems gegenueber einem Inertialsystem bestimmt werden kann. Eine Gruppe von Drehratensensoren sind die sogenannten optischen Kreisel, die im folgenden naeher besprochen werden. Ein solcher faseroptischer Drehratensensor wurde im Rahmen eines von der DFG gefoerderten Pilotprojektes in Zusammenarbeit mit dem Geophysikalischen Institut der Universitaet Goettingen in ein Bohrlochmagnetometer eingebaut. Ziel des Pilotprojektes war es zu testen, mit welcher Genauigkeit die Horizontalkomponenten des Magnetometers mithilfe des faseroptischen Kreisels in Bezug auf ein erdfestes Koordinatensystem ausgerichtet werden koennen. Dieses Messsystem wurde in einer Ozeanbohrung im NW-Pazifik eingesetzt, mit dem Ziel den remanente Anteil des Magnetfeldes der stark magnetischen ozeanischen Kruste und dessen Richtung zu bestimmen. Mit diesem Sensor steht ein Messverfahren zur Verfuegung, das vom Magnetfeld als Orientierungshilfe vollstaendig unabhaengig ist. Weitere Anwendungsmoeglichkeiten dieser Messtechnik sind die online Vermessung der Geometrie von Bohrungen oder Kavernen und die nachtraegliche Orientierung von Abbildungen der Bohrlochwand mittels bildgebender
Optimization and Experimentation of Dual-Mass MEMS Gyroscope Quadrature Error Correction Methods
Directory of Open Access Journals (Sweden)
Huiliang Cao
2016-01-01
Full Text Available This paper focuses on an optimal quadrature error correction method for the dual-mass MEMS gyroscope, in order to reduce the long term bias drift. It is known that the coupling stiffness and demodulation error are important elements causing bias drift. The coupling stiffness in dual-mass structures is analyzed. The experiment proves that the left and right masses’ quadrature errors are different, and the quadrature correction system should be arranged independently. The process leading to quadrature error is proposed, and the Charge Injecting Correction (CIC, Quadrature Force Correction (QFC and Coupling Stiffness Correction (CSC methods are introduced. The correction objects of these three methods are the quadrature error signal, force and the coupling stiffness, respectively. The three methods are investigated through control theory analysis, model simulation and circuit experiments, and the results support the theoretical analysis. The bias stability results based on CIC, QFC and CSC are 48 °/h, 9.9 °/h and 3.7 °/h, respectively, and this value is 38 °/h before quadrature error correction. The CSC method is proved to be the better method for quadrature correction, and it improves the Angle Random Walking (ARW value, increasing it from 0.66 °/√h to 0.21 °/√h. The CSC system general test results show that it works well across the full temperature range, and the bias stabilities of the six groups’ output data are 3.8 °/h, 3.6 °/h, 3.4 °/h, 3.1 °/h, 3.0 °/h and 4.2 °/h, respectively, which proves the system has excellent repeatability.
Optimization and Experimentation of Dual-Mass MEMS Gyroscope Quadrature Error Correction Methods
Cao, Huiliang; Li, Hongsheng; Kou, Zhiwei; Shi, Yunbo; Tang, Jun; Ma, Zongmin; Shen, Chong; Liu, Jun
2016-01-01
This paper focuses on an optimal quadrature error correction method for the dual-mass MEMS gyroscope, in order to reduce the long term bias drift. It is known that the coupling stiffness and demodulation error are important elements causing bias drift. The coupling stiffness in dual-mass structures is analyzed. The experiment proves that the left and right masses’ quadrature errors are different, and the quadrature correction system should be arranged independently. The process leading to quadrature error is proposed, and the Charge Injecting Correction (CIC), Quadrature Force Correction (QFC) and Coupling Stiffness Correction (CSC) methods are introduced. The correction objects of these three methods are the quadrature error signal, force and the coupling stiffness, respectively. The three methods are investigated through control theory analysis, model simulation and circuit experiments, and the results support the theoretical analysis. The bias stability results based on CIC, QFC and CSC are 48 °/h, 9.9 °/h and 3.7 °/h, respectively, and this value is 38 °/h before quadrature error correction. The CSC method is proved to be the better method for quadrature correction, and it improves the Angle Random Walking (ARW) value, increasing it from 0.66 °/√h to 0.21 °/√h. The CSC system general test results show that it works well across the full temperature range, and the bias stabilities of the six groups’ output data are 3.8 °/h, 3.6 °/h, 3.4 °/h, 3.1 °/h, 3.0 °/h and 4.2 °/h, respectively, which proves the system has excellent repeatability. PMID:26751455
Design and Simulation of a MEMS Control Moment Gyroscope for the Sub-Kilogram Spacecraft
Directory of Open Access Journals (Sweden)
Weizheng Yuan
2010-04-01
Full Text Available A novel design of a microelectromechanical systems (MEMS control moment gyroscope (MCMG was proposed in this paper in order to generate a torque output with a magnitude of 10-6 N∙m. The MCMG consists of two orthogonal angular vibration systems, i.e., the rotor and gimbal; the coupling between which is based on the Coriolis effect and will cause a torque output in the direction perpendicular to the two vibrations. The angular rotor vibration was excited by the in-plane electrostatic rotary comb actuators, while the angular gimbal vibration was driven by an out-of-plane electrostatic parallel plate actuator. A possible process flow to fabricate the structure was proposed and discussed step by step. Furthermore, an array configuration using four MCMGs as an effective element, in which the torque was generated with a phase difference of 90 degrees between every two MCMGs, was proposed to smooth the inherent fluctuation of the torque output for a vibrational MCMG. The parasitic torque was cancelled by two opposite MCMGs with a phase difference of 180 degrees. The designed MCMG was about 1.1 cm × 1.1 cm × 0.04 cm in size and 0.1 g in weight. The simulation results showed that the maximum torque output of a MCMG, the resonant frequency of which was approximately 1,000 Hz, was about 2.5 × 10-8 N∙m. The element with four MCMGs could generate a torque of 5 × 10-8 N∙m. The torque output could reach a magnitude of 10-6 N∙m when the frequency was improved from 1,000 Hz to 10,000 Hz. Using arrays of 4 × 4 effective elements on a 1 kg spacecraft with a standard form factor of 10 cm × 10 cm × 10 cm, a 10 degrees attitude change could be achieved in 26.96s.
Gravitational Physics Research
Wu, S. T.
2000-01-01
Gravitational physics research at ISPAE is connected with NASA's Relativity Mission (Gravity Probe B (GP-B)) which will perform a test of Einstein's General Relativity Theory. GP-B will measure the geodetic and motional effect predicted by General Relativity Theory with extremely stable and sensitive gyroscopes in an earth orbiting satellite. Both effects cause a very small precession of the gyroscope spin axis. The goal of the GP-B experiment is the measurement of the gyroscope precession with very high precision. GP-B is being developed by a team at Stanford University and is scheduled for launch in the year 2001. The related UAH research is a collaboration with Stanford University and MSFC. This research is focussed primarily on the error analysis and data reduction methods of the experiment but includes other topics concerned with experiment systems and their performance affecting the science measurements. The hydrogen maser is the most accurate and stable clock available. It will be used in future gravitational physics missions to measure relativistic effects such as the second order Doppler effect. The HMC experiment, currently under development at the Smithsonian Astrophysical Observatory (SAO), will test the performance and capability of the hydrogen maser clock for gravitational physics measurements. UAH in collaboration with the SAO science team will study methods to evaluate the behavior and performance of the HMC. The GP-B data analysis developed by the Stanford group involves complicated mathematical operations. This situation led to the idea to investigate alternate and possibly simpler mathematical procedures to extract the GP-B measurements form the data stream. Comparison of different methods would increase the confidence in the selected scheme.
International Nuclear Information System (INIS)
Çelikel, Oğuz; Sametoğlu, Ferhat
2012-01-01
In this study, a novel interferometric fiber optic gyroscope (IFOG), which has a different depolarizer structure, is designed in TUBITAK UME (National Metrology Institute of Turkey) to experimentally and relatively evaluate the effect of the degree of polarization on the Faraday effect-based drift of the light waves injected into both arms of a Sagnac interferometer. In order to observe whether or not any change occurs in the Faraday-based drift, depending on the variations in degree of polarization (DOP), a triple structure-depolarizer IFOG possessing adjustable DOP is firstly designed and prototyped. The minimum DOP achieved with triple structure-depolarizers is typically 0.15% for both clockwise (CW) and counterclockwise (CCW) light waves at both arms of the Sagnac interferometer. The experimental evaluations about the drift are given for DOP changes extending from 78.00% to 0.15% together with two main and different theoretical approaches in the literature. According to the experimental evaluations given herein, it is experimentally proved that the Faraday-based drift does not change depending on DOP values of both CW and CCW light waves injected into the single-mode (SM) sensing coil and it is impossible to state a concept of a depolarized IFOG by considering the polarization state at the entrance arms of the SM sensing coil. (paper)
Simonelli, A.; Belfi, J.; Beverini, N.; Di Virgilio, A.; Giacomelli, U.; De Luca, G.; Igel, H.
2017-12-01
We report the observation and analysis of the MW 8.1 Tehuantepec earthquake-induced rotational ground motion as observed by the Gingerino ring laser gyroscope (RLG).This instrument is located inside the National laboratory of the "Istituto Nazionale di Fisica Nucleare" in Gran Sasso (Italy) in a deep underground environment.We compare the vertical rotation rate with the horizontal acceleration measured by a co-located broadband seismometer. This analysis, performed by means of a wavelet-based correlation method, permits to identify the G1,G2,G3,G4 onsets of the surface Love waves in the 120 to 280 seconds period range.
LeMoyne, Robert; Mastroianni, Timothy
2016-08-01
Natural gait consists of synchronous and rhythmic patterns for both the lower and upper limb. People with hemiplegia can experience reduced arm swing, which can negatively impact the quality of gait. Wearable and wireless sensors, such as through a smartphone, have demonstrated the ability to quantify various features of gait. With a software application the smartphone (iPhone) can function as a wireless gyroscope platform capable of conveying a gyroscope signal recording as an email attachment by wireless connectivity to the Internet. The gyroscope signal recordings of the affected hemiplegic arm with reduced arm swing arm and the unaffected arm are post-processed into a feature set for machine learning. Using a multilayer perceptron neural network a considerable degree of classification accuracy is attained to distinguish between the affected hemiplegic arm with reduced arm swing arm and the unaffected arm.
Chang, Ming-Hui; Huang, Han-Pang
2013-01-01
This paper presents a novel parasitic-insensitive switched-capacitor (PISC) sensing circuit design in order to obtain high sensitivity and ultra linearity and reduce the parasitic effect for the out-of-plane single-gimbaled decoupled CMOS-MEMS gyroscope (SGDG). According to the simulation results, the proposed PISC circuit has better sensitivity and high linearity in a wide dynamic range. Experimental results also show a better performance. In addition, the PISC circuit can use signal processing to cancel the offset and noise. Thus, this circuit is very suitable for gyroscope measurement. PMID:23493122
Effect of Space Vehicle Structure Vibration on Control Moment Gyroscope Dynamics
Dobrinskaya, Tatiana
2008-01-01
Control Moment Gyroscopes (CMGs) are used for non-propulsive attitude control of satellites and space stations, including the International Space Station (ISS). CMGs could be essential for future long duration space missions due to the fact that they help to save propellant. CMGs were successfully tested on the ground for many years, and have been successfully used on satellites. However, operations have shown that the CMG service life on the ISS is significantly shorter than predicted. Since the dynamic environment of the ISS differs greatly from the nominal environment of satellites, it was important to analyze how operations specific to the station (dockings and undockings, huge solar array motion, crew exercising, robotic operations, etc) can affect the CMG performance. This task became even more important since the first CMG failure onboard the ISS. The CMG failure resulted in the limitation of the attitude control capabilities, more propellant consumption, and additional operational issues. Therefore, the goal of this work was to find out how the vibrations of a space vehicle structure, caused by a variety of onboard operations, can affect the CMG dynamics and performance. The equations of CMG motion were derived and analyzed for the case when the gyro foundation can vibrate in any direction. The analysis was performed for unbalanced CMG gimbals to match the CMG configuration on ISS. The analysis showed that vehicle structure vibrations can amplify and significantly change the CMG motion if the gyro gimbals are unbalanced in flight. The resonance frequencies were found. It was shown that the resonance effect depends on the magnitude of gimbal imbalance, on the direction of a structure vibration, and on gimbal bearing friction. Computer modeling results of CMG dynamics affected by the external vibration are presented. The results can explain some of the CMG vibration telemetry observed on ISS. This work shows that balancing the CMG gimbals decreases the effect
Directory of Open Access Journals (Sweden)
Valérie Renaudin
2014-12-01
Full Text Available The dependence of proposed pedestrian navigation solutions on a dedicated infrastructure is a limiting factor to the deployment of location based services. Consequently self-contained Pedestrian Dead-Reckoning (PDR approaches are gaining interest for autonomous navigation. Even if the quality of low cost inertial sensors and magnetometers has strongly improved, processing noisy sensor signals combined with high hand dynamics remains a challenge. Estimating accurate attitude angles for achieving long term positioning accuracy is targeted in this work. A new Magnetic, Acceleration fields and GYroscope Quaternion (MAGYQ-based attitude angles estimation filter is proposed and demonstrated with handheld sensors. It benefits from a gyroscope signal modelling in the quaternion set and two new opportunistic updates: magnetic angular rate update (MARU and acceleration gradient update (AGU. MAGYQ filter performances are assessed indoors, outdoors, with dynamic and static motion conditions. The heading error, using only the inertial solution, is found to be less than 10° after 1.5 km walking. The performance is also evaluated in the positioning domain with trajectories computed following a PDR strategy.
Teng, Fei; Jin, Jing; Li, Yong; Zhang, Chunxi
2018-05-01
The contribution of modulator drive circuit noise as a 1/f noise source to the output noise of the high-sensitivity interferometric fiber optic gyroscope (IFOG) was studied here. A noise model of closed-loop IFOG was built. By applying the simulated 1/f noise sequence into the model, a gyroscope output data series was acquired, and the corresponding power spectrum density (PSD) and the Allan variance curve were calculated to analyze the noise characteristic. The PSD curve was in the spectral shape of 1/f, which verifies that the modulator drive circuit induced a low frequency 1/f phase noise into the gyroscope. The random walk coefficient (RWC), a standard metric to characterize the noise performance of the IFOG, was calculated according to the Allan variance curve. Using an operational amplifier with an input 1/f noise of 520 nV/√Hz at 1 Hz, the RWC induced by this 1/f noise was 2 × 10-4°/√h, which accounts for 63% of the total RWC. To verify the correctness of the noise model we proposed, a high-sensitivity gyroscope prototype was built and tested. The simulated Allan variance curve gave a good rendition of the prototype actual measured curve. The error percentage between the simulated RWC and the measured value was less than 13%. According to the model, a noise reduction method is proposed and the effectiveness is verified by the experiment.
Development of a New Surface Acoustic Wave Based Gyroscope on a X-112°Y LiTaO3 Substrate
Directory of Open Access Journals (Sweden)
Shitang He
2011-11-01
Full Text Available A new micro gyroscope based on the surface acoustic wave (SAW gyroscopic effect was developed. The SAW gyroscopic effect is investigated by applying the surface effective permittivity method in the regime of small ratios of the rotation velocity and the frequency of the SAW. The theoretical analysis indicates that the larger velocity shift was observed from the rotated X-112°Y LiTaO3 substrate. Then, two SAW delay lines with reverse direction and an operation frequency of 160 MHz are fabricated on a same X-112°Y LiTaO3 chip as the feedback of two SAW oscillators, which act as the sensor element. The single-phase unidirectional transducer (SPUDT and combed transducers were used to structure the delay lines to improve the frequency stability of the oscillator. The rotation of a piezoelectric medium gives rise to a shift of the propagation velocity of SAW due to the Coriolis force, resulting in the frequency shift of the SAW device, and hence, the evaluation of the sensor performance. Meanwhile, the differential structure was performed to double the sensitivity and compensate for the temperature effects. Using a precise rate table, the performance of the fabricated SAW gyroscope was evaluated experimentally. A sensitivity of 1.332 Hz deg−1 s at angular rates of up to 1,000 deg s−1 and good linearity are observed.
A confirmation of the general relativistic prediction of the Lense-Thirring effect.
Ciufolini, I; Pavlis, E C
2004-10-21
An important early prediction of Einstein's general relativity was the advance of the perihelion of Mercury's orbit, whose measurement provided one of the classical tests of Einstein's theory. The advance of the orbital point-of-closest-approach also applies to a binary pulsar system and to an Earth-orbiting satellite. General relativity also predicts that the rotation of a body like Earth will drag the local inertial frames of reference around it, which will affect the orbit of a satellite. This Lense-Thirring effect has hitherto not been detected with high accuracy, but its detection with an error of about 1 per cent is the main goal of Gravity Probe B--an ongoing space mission using orbiting gyroscopes. Here we report a measurement of the Lense-Thirring effect on two Earth satellites: it is 99 +/- 5 per cent of the value predicted by general relativity; the uncertainty of this measurement includes all known random and systematic errors, but we allow for a total +/- 10 per cent uncertainty to include underestimated and unknown sources of error.
International Nuclear Information System (INIS)
Schleich, W.; Dobiasch, P.
1986-01-01
A brief review is given of quantum noise in ring laser gyroscopes. Some the basic elements of ring laser theory, such as the Sagnac effect, the locking effect, and the influence of quantumnoise on the mean beat frequency versus rotation rate are discussed. The Langevin equation for the ase difference between the counterpropagating waves in the presence of any periodic and time symmetric dither is cast into a form which alows a qualitative discussion of the resulting lock-in curve as well as an exact expression in terms of infinite matrix continued fractions. The details of the transformation of the stochastic variable and the derivation of the exact expression for f>t may be found in appendices. Exact results are presented for two special cases of the dithering function: the harmonic and the square-wave bias
Velazquez, Antonio; Swartz, R. Andrew
2013-04-01
Renewable energy sources like wind are important technologies, useful to alleviate for the current fossil-fuel crisis. Capturing wind energy in a more efficient way has resulted in the emergence of more sophisticated designs of wind turbines, particularly Horizontal-Axis Wind Turbines (HAWTs). To promote efficiency, traditional finite element methods have been widely used to characterize the aerodynamics of these types of multi-body systems and improve their design. Given their aeroelastic behavior, tapered-swept blades offer the potential to optimize energy capture and decrease fatigue loads. Nevertheless, modeling special complex geometries requires huge computational efforts necessitating tradeoffs between faster computation times at lower cost, and reliability and numerical accuracy. Indeed, the computational cost and the numerical effort invested, using traditional FE methods, to reproduce dependable aerodynamics of these complex-shape beams are sometimes prohibitive. A condensed Spinning Finite Element (SFE) method scheme is presented in this study aimed to alleviate this issue by means of modeling wind-turbine rotor blades properly with tapered-swept cross-section variations of arbitrary order via Lagrangian equations. Axial-flexural-torsional coupling is carried out on axial deformation, torsion, in-plane bending and out-of-plane bending using super-convergent elements. In this study, special attention is paid for the case of damped yaw effects, expressed within the described skew-symmetric damped gyroscopic matrix. Dynamics of the model are analyzed by achieving modal analysis with complex-number eigen-frequencies. By means of mass, damped gyroscopic, and stiffness (axial-flexural-torsional coupling) matrix condensation (order reduction), numerical analysis is carried out for several prototypes with different tapered, swept, and curved variation intensities, and for a practical range of spinning velocities at different rotation angles. A convergence study
Energy Technology Data Exchange (ETDEWEB)
Fernández-Valdés, D.; Torres-Torres, C., E-mail: ctorrest@ipn.mx, E-mail: crstorres@yahoo.com.mx; Martínez-González, C. L. [Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Ingeniería Mecánica y Eléctrica Unidad Zacatenco (Mexico); Trejo-Valdez, M. [Instituto Politécnico Nacional, Escuela Superior de Ingeniería Química e Industrias Extractivas (Mexico); Hernández-Gómez, L. H. [Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Ingeniería Mecánica y Eléctrica Unidad Zacatenco (Mexico); Torres-Martínez, R. [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada Unidad Querétaro (Mexico)
2016-07-15
The modification in the third-order nonlinear optical response exhibited by rotating bimetallic Au–Pt nanoparticles in an ethanol solution was analyzed. The samples were prepared by a sol–gel processing route. The anisotropy associated to the elemental composition of the nanoparticles was confirmed by high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy measurements. The size of the nanoparticles varies in the range from 9 to 13 nm, with an average size of 11 nm. Changes in the spatial orientation of the nanomaterials automatically generated a variation in their plasmonic response evaluated by UV–Vis spectroscopy. A two-wave mixing experiment was conducted to explore an induced birefringence at 532 nm wavelength with nanosecond pulses interacting with the samples. A strong optical Kerr effect was identified to be the main responsible effect for the third-order nonlinear optical phenomenon exhibited by the nanoparticles. It was estimated that the rotation of inhomogeneous nanostructures can provide a remarkable change in the participation of different surface plasmon resonances, if they correspond to multimetallic nanoparticles. Potential applications for developing low-dimensional gyroscopic systems can be contemplated.
International Nuclear Information System (INIS)
Fernández-Valdés, D.; Torres-Torres, C.; Martínez-González, C. L.; Trejo-Valdez, M.; Hernández-Gómez, L. H.; Torres-Martínez, R.
2016-01-01
The modification in the third-order nonlinear optical response exhibited by rotating bimetallic Au–Pt nanoparticles in an ethanol solution was analyzed. The samples were prepared by a sol–gel processing route. The anisotropy associated to the elemental composition of the nanoparticles was confirmed by high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy measurements. The size of the nanoparticles varies in the range from 9 to 13 nm, with an average size of 11 nm. Changes in the spatial orientation of the nanomaterials automatically generated a variation in their plasmonic response evaluated by UV–Vis spectroscopy. A two-wave mixing experiment was conducted to explore an induced birefringence at 532 nm wavelength with nanosecond pulses interacting with the samples. A strong optical Kerr effect was identified to be the main responsible effect for the third-order nonlinear optical phenomenon exhibited by the nanoparticles. It was estimated that the rotation of inhomogeneous nanostructures can provide a remarkable change in the participation of different surface plasmon resonances, if they correspond to multimetallic nanoparticles. Potential applications for developing low-dimensional gyroscopic systems can be contemplated.
Directory of Open Access Journals (Sweden)
Yanwei Guan
2016-04-01
Full Text Available In this paper, a new micromachined tuning fork gyroscope (TFG with an anchored diamond coupling mechanism is proposed while the mode ordering and the vibration sensitivity are also investigated. The sense-mode of the proposed TFG was optimized through use of an anchored diamond coupling spring, which enables the in-phase mode frequency to be 108.3% higher than the anti-phase one. The frequencies of the in- and anti-phase modes in the sense direction are 9799.6 Hz and 4705.3 Hz, respectively. The analytical solutions illustrate that the stiffness difference ratio of the in- and anti-phase modes is inversely proportional to the output induced by the vibration from the sense direction. Additionally, FEM simulations demonstrate that the stiffness difference ratio of the anchored diamond coupling TFG is 16.08 times larger than the direct coupling one while the vibration output is reduced by 94.1%. Consequently, the proposed new anchored diamond coupling TFG can structurally increase the stiffness difference ratio to improve the mode ordering and considerably reduce the vibration sensitivity without sacrificing the scale factor.
International Nuclear Information System (INIS)
Wang, M C; Jiao, J W; Yan, P L; Mi, B W; Qin, S
2014-01-01
This paper presents a tri-axis MEMS gyroscope design with novel tetra-pendulum proof masses for X-, Y-axis and regular proof masses for Z-axis rate sensing, which are all coupled with and embedded in a conventional tuning fork driving frame. The four pendulum proof masses are suspended via the torsional springs to a common center anchor and can be driven to swing around the anchor via the tilted transforming springs as the driving frame is oscillated in an anti-phase mode. As an X-, Y-axis angular rate is applied, the tetra-pendulum proof masses will rotate around the torsional springs in pairs for X- and Y-axis differential sensing, respectively. In particular, we investigated the relationship between the tilting angle of the transforming spring and its transforming efficiency, i.e. the amplitude ratio of the pendulum's swing to the driving oscillation, which shows a straight impact on the sensitivity. By theoretical analysis and Ansys simulation, we achieved an optimal tilting angle of 22.5°, which extends along the angular bisector of the pendulum's and driving mass’ moving direction and demonstrates a significant increase in transforming efficiency by about 40%, compared with the trivial tilting angle of 45°. By employing an SOI-based bulk micromachining process, the prototype device with the optimal design of the transforming spring (type I) and that with the trivial design (type II) for reference have been successfully fabricated. As expected, the testing results indicate an increase of more than 20% in the X- and Y- sensitivities, which is mainly from the enhanced sensitive transforming springs. (paper)
Simonelli, A.; Igel, H.; Wassermann, J.; Belfi, J.; Di Virgilio, A.; Beverini, N.; De Luca, G.; Saccorotti, G.
2018-05-01
We present the analysis of rotational and translational ground motions from earthquakes recorded during October/November, 2016, in association with the Central Italy seismic-sequence. We use co-located measurements of the vertical ground rotation rate from a large ring laser gyroscope (RLG), and the three components of ground velocity from a broadband seismometer. Both instruments are positioned in a deep underground environment, within the Gran Sasso National Laboratories (LNGS) of the Istituto Nazionale di Fisica Nucleare (INFN). We collected dozens of events spanning the 3.5-5.9 Magnitude range, and epicentral distances between 30 km and 70 km. This data set constitutes an unprecedented observation of the vertical rotational motions associated with an intense seismic sequence at local distance. Under the plane wave approximation we process the data set in order to get an experimental estimation of the events back azimuth. Peak values of rotation rate (PRR) and horizontal acceleration (PGA) are markedly correlated, according to a scaling constant which is consistent with previous measurements from different earthquake sequences. We used a prediction model in use for Italy to calculate the expected PGA at the recording site, obtaining consequently predictions for PRR. Within the modeling uncertainties, predicted rotations are consistent with the observed ones, suggesting the possibility of establishing specific attenuation models for ground rotations, like the scaling of peak velocity and peak acceleration in empirical ground-motion prediction relationships. In a second step, after identifying the direction of the incoming wave-field, we extract phase velocity data using the spectral ratio of the translational and rotational components.. This analysis is performed over time windows associated with the P-coda, S-coda and Lg phase. Results are consistent with independent estimates of shear-wave velocities in the shallow crust of the Central Apennines.
Directory of Open Access Journals (Sweden)
Colin Ware
Full Text Available Forces due to propulsion should approximate forces due to hydrodynamic drag for animals horizontally swimming at a constant speed with negligible buoyancy forces. Propulsive forces should also correlate with energy expenditures associated with locomotion-an important cost of foraging. As such, biologging tags containing accelerometers are being used to generate proxies for animal energy expenditures despite being unable to distinguish rotational movements from linear movements. However, recent miniaturizations of gyroscopes offer the possibility of resolving this shortcoming and obtaining better estimates of body accelerations of swimming animals. We derived accelerations using gyroscope data for swimming Steller sea lions (Eumetopias jubatus, and determined how well the measured accelerations correlated with actual swimming speeds and with theoretical drag. We also compared dive averaged dynamic body acceleration estimates that incorporate gyroscope data, with the widely used Overall Dynamic Body Acceleration (ODBA metric, which does not use gyroscope data. Four Steller sea lions equipped with biologging tags were trained to swim alongside a boat cruising at steady speeds in the range of 4 to 10 kph. At each speed, and for each dive, we computed a measure called Gyro-Informed Dynamic Acceleration (GIDA using a method incorporating gyroscope data with accelerometer data. We derived a new metric-Averaged Propulsive Body Acceleration (APBA, which is the average gain in speed per flipper stroke divided by mean stroke cycle duration. Our results show that the gyro-based measure (APBA is a better predictor of speed than ODBA. We also found that APBA can estimate average thrust production during a single stroke-glide cycle, and can be used to estimate energy expended during swimming. The gyroscope-derived methods we describe should be generally applicable in swimming animals where propulsive accelerations can be clearly identified in the signal
Spin-Neto, Rubens; Matzen, Louise H; Schropp, Lars; Gotfredsen, Erik; Wenzel, Ann
2017-02-01
To compare video observation (VO) with a novel three-dimensional registration method, based on an accelerometer-gyroscope (AG) system, to detect patient movement during CBCT examination. The movements were further analyzed according to complexity and patient age. In 181 patients (118 females/63 males; age average 30 years, range: 9-84 years), 206 CBCT examinations were performed, which were video-recorded during examination. An AG was, at the same time, attached to the patient head to track head position in three dimensions. Three observers scored patient movement (yes/no) by VO. AG provided movement data on the x-, y- and z-axes. Thresholds for AG-based registration were defined at 0.5, 1, 2, 3 and 4 mm (movement distance). Movement detected by VO was compared with that registered by AG, according to movement complexity (uniplanar vs multiplanar, as defined by AG) and patient age (≤15, 16-30 and ≥31 years). According to AG, movement ≥0.5 mm was present in 160 (77.7%) examinations. According to VO, movement was present in 46 (22.3%) examinations. One VO-detected movement was not registered by AG. Overall, VO did not detect 71.9% of the movements registered by AG at the 0.5-mm threshold. At a movement distance ≥4 mm, 20% of the AG-registered movements were not detected by VO. Multiplanar movements such as lateral head rotation (72.1%) and nodding/swallowing (52.6%) were more often detected by VO in comparison with uniplanar movements, such as head lifting (33.6%) and anteroposterior translation (35.6%), at the 0.5-mm threshold. The prevalence of patients who move was highest in patients younger than 16 years (64.3% for VO and 92.3% for AG-based registration at the 0.5-mm threshold). AG-based movement registration resulted in a higher prevalence of patient movement during CBCT examination than VO-based registration. Also, AG-registered multiplanar movements were more frequently detected by VO than uniplanar movements. The prevalence of patients who move
Simonelli, Andreino; Belfi, Jacopo; Beverini, Nicolò; Di Virgilio, Angela; Maccioni, Enrico; De Luca, Gaetano; Saccorotti, Gilberto; Wassermann, Joachim; Igel, Heiner
2017-04-01
We present analyses of rotational and translational ground motions from earthquakes recorded during October-November, 2016, in association with the Central Italy seismic-sequence. We use co-located measurements of the vertical ground rotation rate from a large ring laser gyroscope (RLG), and the three components of ground velocity from a broadband seismometer. Both instruments are positioned in a deep underground environment, within the Gran Sasso National Laboratories (LNGS) of the Istituto Nazionale di Fisica Nucleare (INFN). We collected dozen of events spanning the 3.5-5.9 Magnitude range, and epicentral distances between 40 km and 80 km. This data set constitutes an unprecedented observation of the vertical rotational motions associated with an intense seismic sequence at local distance. In theory - assuming plane wave propagation - the ratio between the vertical rotation rate and the transverse acceleration permits, in a single station approach, the estimation of apparent phase velocity in the case of SH arrivals or real phase velocity in the case of Love surface waves. This is a standard approach for the analysis of earthquakes at teleseismic distances, and the results reported by the literature are compatible with the expected phase velocities from the PREM model. Here we extend the application of the same approach to local events, thus exploring higher frequency ranges and larger rotation rate amplitudes. We use a novel approach to joint rotation/acceleration analysis based on the continuous wavelet transform (CWT). Wavelet coherence (WTC) is used as a filter for identifying those regions of the time-period plane where the rotation rate and transverse acceleration signals exhibit significant coherence. This allows retrieving estimates of phase velocities over the period range spanned by correlated arrivals. Coherency among ground rotation and translation is also observed throughout the coda of the P-wave arrival, an observation which is interpreted in
Ishigaki, Norio; Kimura, Teiji; Usui, Yuki; Aoki, Kaoru; Narita, Nobuyo; Shimizu, Masayuki; Hara, Kazuo; Ogihara, Nobuhide; Nakamura, Koichi; Kato, Hiroyuki; Ohira, Masayoshi; Yokokawa, Yoshiharu; Miyoshi, Kei; Murakami, Narumichi; Okada, Shinpei; Nakamura, Tomokazu; Saito, Naoto
2011-06-03
The incidence of falls in the elderly is increasing with the aging of society and is becoming a major public health issue. From the viewpoint of prevention of falls, it is important to evaluate the stability of the gait in the elderly people. The pelvic movement, which is a critical factor for walking stability, was analyzed using a posture monitoring system equipped with a triaxial accelerometer and a gyroscope. The subjects were 95 elderly people over 60 years of age. The criteria for instability were open-eye standing on one leg for 15s or less, and 11s or more on 3m timed up and go test. Forty subjects who did not meet both of these criteria comprised the stable group, and the remaining 55 subjects comprised the unstable group. Pelvic movement during walking was compared between the two groups. The angle, angular velocity, and acceleration were analyzed based on the wave shape derived from the device worn around the second sacral. The results indicated that pelvic movement was lower in all three directions in the unstable group compared to the stable group, and the changes in the pelvic movement during walking in unstable elderly people were also reduced. This report is the first to evaluate pelvic movement by both a triaxial accelerometer and a triaxial gyroscope simultaneously. The characteristics of pelvic movement during walking can be applied in screening to identify elderly people with instability, which is the main risk factor associated with falls. Copyright © 2011 Elsevier Ltd. All rights reserved.
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Yuri F. Katorin
2016-09-01
Full Text Available In the article it is described about the attack at night 16 of May 1943 of year by the English aircraft of 617-y of the squadron of German dams in the Ruhr pond with the use of bombs “Upkeep” and the history of their creation by designer Barns Neville Wallis, is described the device of this weapon and the tactics of its application. The motion of operation is analyzed, in detail it is told about the actions of the crews of the aircraft, тhe motion of operation is analyzed, the losses of sides and consequence of the destruction of dams for the German defense industry are given.
Nuclear magnetic resonance gyroscope
International Nuclear Information System (INIS)
Grover, B.C.
1984-01-01
A nuclear magnetic resonance gyro using two nuclear magnetic resonance gases, preferably xenon 129 and xenon 131, together with two alkaline metal vapors, preferably rubidium, potassium or cesium, one of the two alkaline metal vapors being pumped by light which has the wavelength of that alkaline metal vapor, and the other alkaline vapor being illuminated by light which has the wavelength of that other alkaline vapor
Einstein, Albert
2013-01-01
Time magazine's ""Man of the Century"", Albert Einstein is the founder of modern physics and his theory of relativity is the most important scientific idea of the modern era. In this short book, Einstein explains, using the minimum of mathematical terms, the basic ideas and principles of the theory that has shaped the world we live in today. Unsurpassed by any subsequent books on relativity, this remains the most popular and useful exposition of Einstein's immense contribution to human knowledge.With a new foreword by Derek Raine.
Shen, Chong; Li, Jie; Zhang, Xiaoming; Shi, Yunbo; Tang, Jun; Cao, Huiliang; Liu, Jun
2016-05-31
The different noise components in a dual-mass micro-electromechanical system (MEMS) gyroscope structure is analyzed in this paper, including mechanical-thermal noise (MTN), electronic-thermal noise (ETN), flicker noise (FN) and Coriolis signal in-phase noise (IPN). The structure equivalent electronic model is established, and an improved white Gaussian noise reduction method for dual-mass MEMS gyroscopes is proposed which is based on sample entropy empirical mode decomposition (SEEMD) and time-frequency peak filtering (TFPF). There is a contradiction in TFPS, i.e., selecting a short window length may lead to good preservation of signal amplitude but bad random noise reduction, whereas selecting a long window length may lead to serious attenuation of the signal amplitude but effective random noise reduction. In order to achieve a good tradeoff between valid signal amplitude preservation and random noise reduction, SEEMD is adopted to improve TFPF. Firstly, the original signal is decomposed into intrinsic mode functions (IMFs) by EMD, and the SE of each IMF is calculated in order to classify the numerous IMFs into three different components; then short window TFPF is employed for low frequency component of IMFs, and long window TFPF is employed for high frequency component of IMFs, and the noise component of IMFs is wiped off directly; at last the final signal is obtained after reconstruction. Rotation experimental and temperature experimental are carried out to verify the proposed SEEMD-TFPF algorithm, the verification and comparison results show that the de-noising performance of SEEMD-TFPF is better than that achievable with the traditional wavelet, Kalman filter and fixed window length TFPF methods.
Directory of Open Access Journals (Sweden)
Chong Shen
2016-05-01
Full Text Available The different noise components in a dual-mass micro-electromechanical system (MEMS gyroscope structure is analyzed in this paper, including mechanical-thermal noise (MTN, electronic-thermal noise (ETN, flicker noise (FN and Coriolis signal in-phase noise (IPN. The structure equivalent electronic model is established, and an improved white Gaussian noise reduction method for dual-mass MEMS gyroscopes is proposed which is based on sample entropy empirical mode decomposition (SEEMD and time-frequency peak filtering (TFPF. There is a contradiction in TFPS, i.e., selecting a short window length may lead to good preservation of signal amplitude but bad random noise reduction, whereas selecting a long window length may lead to serious attenuation of the signal amplitude but effective random noise reduction. In order to achieve a good tradeoff between valid signal amplitude preservation and random noise reduction, SEEMD is adopted to improve TFPF. Firstly, the original signal is decomposed into intrinsic mode functions (IMFs by EMD, and the SE of each IMF is calculated in order to classify the numerous IMFs into three different components; then short window TFPF is employed for low frequency component of IMFs, and long window TFPF is employed for high frequency component of IMFs, and the noise component of IMFs is wiped off directly; at last the final signal is obtained after reconstruction. Rotation experimental and temperature experimental are carried out to verify the proposed SEEMD-TFPF algorithm, the verification and comparison results show that the de-noising performance of SEEMD-TFPF is better than that achievable with the traditional wavelet, Kalman filter and fixed window length TFPF methods.
Saving Space and Time: The Tractor That Einstein Built
2006-01-01
In 1984, NASA initiated the Gravity Probe B (GP-B) program to test two unverified predictions of Albert Einstein s theory of general relativity, hypotheses about the ways space, time, light, and gravity relate to each other. To test these predictions, the Space Agency and researchers at Stanford University developed an experiment that would check, with extreme precision, tiny changes in the spin direction of four gyroscopes contained in an Earth satellite orbiting at a 400-mile altitude directly over the Earth s poles. When the program first began, the researchers assessed using Global Positioning System (GPS) technology to control the attitude of the GP-B spacecraft accurately. At that time, the best GPS receivers could only provide accuracy to nearly 1 meter, but the GP-B spacecraft required a system 100 times more accurate. To address this concern, researchers at Stanford designed high-performance, attitude-determining hardware that used GPS signals, perfecting a high-precision form of GPS called Carrier-Phase Differential GPS that could provide continuous real-time position, velocity, time, and attitude sensor information for all axes of a vehicle. The researchers came to the realization that controlling the GP-B spacecraft with this new system was essentially no different than controlling an airplane. Their thinking took a new direction: If this technology proved successful, the airlines and the Federal Aviation Administration (FAA) were ready commercial markets. They set out to test the new technology, the "Integrity Beacon Landing System," using it to automatically land a commercial Boeing 737 over 100 times successfully through Real-Time Kinematic (RTK) GPS technology. The thinking of the researchers shifted again, from automatically landing aircraft, to automating precision farming and construction equipment.
1971-01-01
The need is examined for orbital flight tests of gyroscope, dewar, and other components, in order to reduce the technical and financial risk in performing the relativity experiment. A program is described that would generate engineering data to permit prediction of final performance. Two flight tests are recommended. The first flight would test a dewar smaller than that required for the final flight, but of size and form sufficient to allow extrapolation to the final design. The second flight would use the same dewar design to carry a set of three gyroscopes, which would be evaluated for spinup and drift characteristics for a period of a month or more. A proportional gas control system using boiloff helium gas from the dewar, and having the ability to prevent sloshing of liquid helium, would also be tested.
Štefanička, Tomáš; Ďuračiová, Renata; Seres, Csaba
2017-12-01
As a complex of buildings, the Faculty of Natural Sciences of the Comenius University in Bratislava tends to be difficult to navigate in spite of its size. An indoor navigation application could potentially save a lot of time and frustration. There are currently numerous technologies used in indoor navigation systems. Some of them focus on a high degree of precision and require significant financial investment; others provide only static information about a current location. In this paper we focused on the determination of an approximate location using inertial measurement systems available on most smartphones, i.e., a gyroscope and an accelerometer. The actual position of the device was calculated using "a walk detection method" based on a delayed lack of motion. We have developed an indoor navigation application that relies solely on open source JavaScript libraries to visualize the interior of the building and calculate the shortest path utilizing Dijsktra's routing algorithm. The application logic is located on the client side, so the software is able to work offline. Our solution represents an accessible lowcost and platform-independent web application that can significantly improve navigation at the Faculty of Natural Sciences. Although our application has been developed on a specific building complex, it could be used in other interiors as well.
Swornowski, Pawel J
2013-01-01
The article presents the application of neural networks in determining and correction of the deformation of a coordinate measuring machine (CMM) workspace. The information about the CMM errors is acquired using an ADXRS401 electronic gyroscope. A test device (PS-20 module) was built and integrated with a commercial measurement system based on the SP25M passive scanning probe and with a PH10M module (Renishaw). The proposed solution was tested on a Kemco 600 CMM and on a DEA Global Clima CMM. In the former case, correction of the CMM errors was performed using the source code of WinIOS software owned by The Institute of Advanced Manufacturing Technology, Cracow, Poland and in the latter on an external PC. Optimum parameters of full and simplified mapping of a given layer of the CMM workspace were determined for practical applications. The proposed method can be employed for the interim check (ISO 10360-2 procedure) or to detect local CMM deformations, occurring when the CMM works at high scanning speeds (>20 mm/s). © Wiley Periodicals, Inc.
Chouvion, B.; McWilliam, S.; Popov, A. A.
2018-06-01
This paper investigates the dynamic behaviour of capacitive ring-based Coriolis Vibrating Gyroscopes (CVGs) under severe shock conditions. A general analytical model is developed for a multi-supported ring resonator by describing the in-plane ring response as a finite sum of modes of a perfect ring and the electrostatic force as a Taylor series expansion. It is shown that the supports can induce mode coupling and that mode coupling occurs when the shock is severe and the electrostatic forces are nonlinear. The influence of electrostatic nonlinearity is investigated by numerically simulating the governing equations of motion. For the severe shock cases investigated, when the electrode gap reduces by ∼ 60 % , it is found that three ring modes of vibration (1 θ, 2 θ and 3 θ) and a 9th order force expansion are needed to obtain converged results for the global shock behaviour. Numerical results when the 2 θ mode is driven at resonance indicate that electrostatic nonlinearity introduces mode coupling which has potential to reduce sensor performance under operating conditions. Under some circumstances it is also found that severe shocks can cause the vibrating response to jump to another stable state with much lower vibration amplitude. This behaviour is mainly a function of shock amplitude and rigid-body motion damping.
Viswanathan, Sasi Prabhakaran
Design, dynamics, control and implementation of a novel spacecraft attitude control actuator called the "Adaptive Singularity-free Control Moment Gyroscope" (ASCMG) is presented in this dissertation. In order to construct a comprehensive attitude dynamics model of a spacecraft with internal actuators, the dynamics of a spacecraft with an ASCMG, is obtained in the framework of geometric mechanics using the principles of variational mechanics. The resulting dynamics is general and complete model, as it relaxes the simplifying assumptions made in prior literature on Control Moment Gyroscopes (CMGs) and it also addresses the adaptive parameters in the dynamics formulation. The simplifying assumptions include perfect axisymmetry of the rotor and gimbal structures, perfect alignment of the centers of mass of the gimbal and the rotor etc. These set of simplifying assumptions imposed on the design and dynamics of CMGs leads to adverse effects on their performance and results in high manufacturing cost. The dynamics so obtained shows the complex nonlinear coupling between the internal degrees of freedom associated with an ASCMG and the spacecraft bus's attitude motion. By default, the general ASCMG cluster can function as a Variable Speed Control Moment Gyroscope, and reduced to function in CMG mode by spinning the rotor at constant speed, and it is shown that even when operated in CMG mode, the cluster can be free from kinematic singularities. This dynamics model is then extended to include the effects of multiple ASCMGs placed in the spacecraft bus, and sufficient conditions for non-singular ASCMG cluster configurations are obtained to operate the cluster both in VSCMG and CMG modes. The general dynamics model of the ASCMG is then reduced to that of conventional VSCMGs and CMGs by imposing the standard set of simplifying assumptions used in prior literature. The adverse effects of the simplifying assumptions that lead to the complexities in conventional CMG design, and
International Nuclear Information System (INIS)
Li, Yang; Chen, Xingfan; Liu, Cheng
2015-01-01
The frequency characteristic is an important indicator of a system’s dynamic performance. The identification of a fiber optic gyroscope (FOG)’s frequency characteristic using a correlation spectrum analysis method based on a pseudo-random sequence is proposed. Taking the angle vibrator as the source of the test rotation stimulation and a pseudo-random sequence as the test signal, the frequency characteristic of a FOG is calculated according to the power spectral density of the rotation rate signal and the cross-power spectral density of the FOG’s output signal and rotation rate signal. A theoretical simulation is done to confirm the validity of this method. An experiment system is built and the test results indicate that the measurement error of the normalized amplitude–frequency response is less than 0.01, that the error of the phase–frequency response is less than 0.3 rad, and the overall measurement accuracy is superior to the traditional frequency-sweep method. By using this method, the FOG’s amplitude–frequency response and phase–frequency response can be measured simultaneously, quickly, accurately, and with a high frequency resolution. The described method meets the requirements of engineering applications. (paper)
Relative Status Determination for Spacecraft Relative Motion Based on Dual Quaternion
Directory of Open Access Journals (Sweden)
Jun Sun
2014-01-01
Full Text Available For the two-satellite formation, the relative motion and attitude determination algorithm is a key component that affects the flight quality and mission efficiency. The relative status determination algorithm is proposed based on the Extended Kalman Filter (EKF and the system state optimal estimate linearization. Aiming at the relative motion of the spacecraft formation navigation problem, the spacecraft relative kinematics and dynamics model are derived from the dual quaternion in the algorithm. Then taking advantage of EKF technique, combining with the dual quaternion integrated dynamic models, considering the navigation algorithm using the fusion measurement by the gyroscope and star sensors, the relative status determination algorithm is designed. At last the simulation is done to verify the feasibility of the algorithm. The simulation results show that the EKF algorithm has faster convergence speed and higher accuracy.
Photonic-crystal fibers gyroscope
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Ali Muse Haider
2015-01-01
Full Text Available In this paper we proposed to use of a photonic crystal fiber with an inner hollow defect. The use of such fibers is not affected by a material medium on the propagation of optical radiation. Photonic crystal fibers present special properties and capabilities that lead to an outstanding potential for sensing applications
Ultrahigh enhancement in absolute and relative rotation sensing using fast and slow light
International Nuclear Information System (INIS)
Shahriar, M. S.; Pati, G. S.; Tripathi, R.; Gopal, V.; Messall, M.; Salit, K.
2007-01-01
We describe a resonator-based optical gyroscope whose sensitivity for measuring absolute rotation is enhanced via use of the anomalous dispersion characteristic of superluminal light propagation. The enhancement is given by the inverse of the group index, saturating to a bound determined by the group velocity dispersion. We also show how the offsetting effect of the concomitant broadening of the resonator linewidth may be circumvented by using an active cavity. For realistic conditions, the enhancement factor is as high as 10 6 . We also show how normal dispersion used for slow light can enhance relative rotation sensing in a specially designed Sagnac interferometer, with the enhancement given by the slowing factor
Machian effects in general relativity
International Nuclear Information System (INIS)
Embacher, F.
1988-01-01
As a consequence of Mach's principle, rotating matter should cause local inertial frames or gyroscopes in its vicinity to undergo a small rotation which is not present in the Newtonian picture. H. Thirring and J. Lense were the first to derive similar predictions from the field equations of general relativity. Since these early days of relativity, a lot of exact and approximate solutions to Einstein's equations have been examined under this point of view. The qualitative features of Machian effects are most easily demonstrated in the cylinder symmetric case, where some exact results are available. For example, space-time is flat inside a uniformly rotating matter shell, and the rotation of this interior with respect to 'infinity' (the distant stars) has a clear meaning. In the more realistic case of what happens near a massive rotating star, one is forced to perform certain approximations. In modern language, Machian effects are described in terms of the twist of timelike killing vector fields. In the linearized theory, the equations that determine the Machian structure generated by a given matter distribution, resemble to some extent those of classical electrodynamics. This correspondence provides a pedagogical approach how to compute the quantitative extent of inertial frame 'dragging'. 6 refs., 5 figs. (Author)
Engineering aspects of the Stanford relativity gyro experiment
Everitt, C. W. F.; Debra, D. B.
1981-01-01
According to certain theoretical predictions, the Newtonian laws of motion must be corrected for the effect of a gravitational field. Schiff (1960) proposed an experiment which would demonstrate the effect predicted by Einstein's Theory of General Relativity on a gyroscope. The experiment has been under development at Stanford University since 1961. The requirements involved make it necessary that the test be performed in a satellite to take advantage of weightlessness in space. In a discussion of engineering developments related to the experiment, attention is given to the development of proportional helium thrusters, the simulation of the attitude control system, aspects of inner loop control, the mechanization of the two-loop attitude control system, the effects of helium slosh on spacecraft pointing, and the data instrumentation system.
Energy Technology Data Exchange (ETDEWEB)
Sandoval R, G.E. [Laboratorio de Optica Aplicada, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, 04510 Mexico D.F. (Mexico); Nikolaev, V.A. [Departamento de Optica y Radiofisica Cuantica, Universidad Estatal de Telecomunicaciones de San Petersburgo, M.A. Bonch-Bruyevich, Kanal Moika 61, Saint Petersburg 191186, (Russian Federation)
2003-07-01
The main objective of this work is to establish the dependence of characteristics of the fiber optics gyroscope (FOG) with respect to the parameters of the super luminescent emission source based on doped optical fiber with rare earth elements (Super luminescent Fiber Source, SFS), argument the pumping rate election of the SFS to obtain characteristics limits of the FOG sensibility. By using this type of emission source in the FOG is recommend to use the rate when the direction of the pumping signal coincide with the super luminescent signal. The most results are the proposition and argumentation of the SFS election as emission source to be use in the FOG of the phase type. Such a decision allow to increase the characteristics of the FOG sensibility in comparison with the use of luminescent source of semiconductors emission which are extensively used in the present time. The use of emission source of the SFS type allow to come closer to the threshold of the obtained sensibility limit (detection limit) which is determined with the shot noise. (Author)
Directory of Open Access Journals (Sweden)
Ramón José Pérez
2016-04-01
Full Text Available This article presents, by means of computational simulation tools, a full analysis and design of an Interferometric Fiber-Optic Gyroscope (IFOG prototype based on a closed-loop configuration with sinusoidal bias phase- modulation. The complete design of the different blocks, optical and electronic, is presented, including some novelties as the sinusoidal bias phase-modulation and the use of an integrator to generate the serrodyne phase-modulation signal. The paper includes detailed calculation of most parameter values, and the plots of the resulting signals obtained from simulation tools. The design is focused in the use of a standard single-mode optical fiber, allowing a cost competitive implementation compared to commercial IFOG, at the expense of reduced sensitivity. The design contains an IFOG model that accomplishes tactical and industrial grade applications (sensitivity ≤ 0.055 °/h. This design presents two important properties: (1 an optical subsystem with advanced conception: depolarization of the optical wave by means of Lyot depolarizers, which allows to use a sensing coil made by standard optical fiber, instead by polarization maintaining fiber, which supposes consequent cost savings and (2 a novel and simple electronic design that incorporates a linear analog integrator with reset in feedback chain, this integrator generating a serrodyne voltage-wave to apply to Phase-Modulator (PM, so that it will be obtained the interferometric phase cancellation. This particular feedback design with sawtooth-wave generated signal for a closed-loop configuration with sinusoidal bias phase modulation has not been reported till now in the scientific literature and supposes a considerable simplification with regard to previous designs based on similar configurations. The sensing coil consists of an 8 cm average diameter spool that contains 300 m of standard single-mode optical-fiber (SMF-28 type realized by quadrupolar winding. The working
Pérez, Ramón José; Álvarez, Ignacio; Enguita, José María
2016-04-27
This article presents, by means of computational simulation tools, a full analysis and design of an Interferometric Fiber-Optic Gyroscope (IFOG) prototype based on a closed-loop configuration with sinusoidal bias phase- modulation. The complete design of the different blocks, optical and electronic, is presented, including some novelties as the sinusoidal bias phase-modulation and the use of an integrator to generate the serrodyne phase-modulation signal. The paper includes detailed calculation of most parameter values, and the plots of the resulting signals obtained from simulation tools. The design is focused in the use of a standard single-mode optical fiber, allowing a cost competitive implementation compared to commercial IFOG, at the expense of reduced sensitivity. The design contains an IFOG model that accomplishes tactical and industrial grade applications (sensitivity ≤ 0.055 °/h). This design presents two important properties: (1) an optical subsystem with advanced conception: depolarization of the optical wave by means of Lyot depolarizers, which allows to use a sensing coil made by standard optical fiber, instead by polarization maintaining fiber, which supposes consequent cost savings and (2) a novel and simple electronic design that incorporates a linear analog integrator with reset in feedback chain, this integrator generating a serrodyne voltage-wave to apply to Phase-Modulator (PM), so that it will be obtained the interferometric phase cancellation. This particular feedback design with sawtooth-wave generated signal for a closed-loop configuration with sinusoidal bias phase modulation has not been reported till now in the scientific literature and supposes a considerable simplification with regard to previous designs based on similar configurations. The sensing coil consists of an 8 cm average diameter spool that contains 300 m of standard single-mode optical-fiber (SMF-28 type) realized by quadrupolar winding. The working wavelength will be
Estimating orientation with gyroscopes and accelerometers
Luinge, Hendrik J.; Veltink, Petrus H.; Baten, Christian T.M.
1999-01-01
Many systems for recording human movement need some reference from beacons near the subject, such as video cameras. Our goal is to measure human kinematics with sensors that are placed on the segments of interest. This way, experiments in which human movement is recorded are not restricted to a lab.
The Anatomy of the Gyroscope. Part 1
1988-02-01
Vysteine Acta Physica Polonica 6 (1937) pp. 163-200 Ma-"rosov, V.M. On the stability of groscopic stabilicea Applied Mathematics & Mechanics 24 (1960...A. The Physical Review 57 (1940) pp.5 2 2 -5 2 7 Bloemnbergen. N. Proposalfior a new type solid state maser PhysicA Review 104 (1956) pp.3 2 4 -3 27...nrot ion of a lop Physica 18 (1952) pp.51i3 -51.. Braddon. F.D. Newitgyrosfor our 5ubmarines Journal of the Franklin Institute 270 (1960) p.7 9
Gyroscopic stabilization and indefimite damped systems
DEFF Research Database (Denmark)
Pommer, Christian
a class of feasibel skew-Hermitian matrices A depending on the choise of M. The theory can be applied to dynamical systems of the form x''(t) + ( dD + g G) x'(t) + K x(t) = 0 where G is a skew symmetric gyrocopic matrix, D is a symmetric indefinite damping matrix and K > 0 is a positive definite stiffness......An important issue is how to modify a given unstable matrix in such a way that the resulting matrix is stable. We investigate in general under which condition a matrix M+A is stable,where M is an arbitrary matrix and A is skew-Hermitian. We show that if trace(M) > 0 it is always possible to find...
Relativity made relatively easy
Steane, Andrew M
2012-01-01
Relativity Made Relatively Easy presents an extensive study of Special Relativity and a gentle (but exact) introduction to General Relativity for undergraduate students of physics. Assuming almost no prior knowledge, it allows the student to handle all the Relativity needed for a university course, with explanations as simple, thorough, and engaging as possible.The aim is to make manageable what would otherwise be regarded as hard; to make derivations as simple as possible and physical ideas as transparent as possible. Lorentz invariants and four-vectors are introduced early on, but tensor not
Scott, Susan M.; McClelland, David E.
2008-06-01
overviews of the state of the art of: observational handles on dark energy; collider physics experiments designed to probe cosmology; gravitational dynamics of large stellar systems; and the use of analogue condensed-matter systems in the laboratory to investigate black hole event horizons. In the more mainstream areas we were given timely reviews of: the Gravity Probe B and STEP missions; quasi-local black hole horizons and their applications; cosmic censorship; the spin foam model approach to quantum gravity; the causal dynamical triangulations approach to quantum gravity; superstring theory applied to questions in particle physics; the current status and prospects for gravitational wave astronomy; ground-based gravitational wave detection; and technological developments for the future LISA mission. This issue is published as the proceedings of GRG18 and Amaldi7. It contains the overview articles by the plenary speakers, the summaries of each GRG18 workshop parallel session as provided by the workshop chairs, and the highlights of the Amaldi7 meeting as selected by the Amaldi7 chairs. Other Amaldi7 talks and posters will appear as articles in a refereed issue of the electronic Journal of Physics Conference Series. This CQG special issue and the related issue of JPCS will be electronically linked. The conference organisers would like to acknowledge the financial support of: The Australian National University; IUPAP; The Australian Institute of Physics; BHP Billiton; The University of Western Australia; The University of New South Wales; The Institute of Physics; The Gravity Research Foundation; SGI; CosNet; The Australian Mathematical Sciences Institute; Springer; Duraduct; the New South Wales Government; The Australasian Society for General Relativity and Gravitation; the Mexican GR bid; the Centre for Precision Optics; The Anglo-Australian Observatory; Newspec; CSIRO; and The University of Melbourne. We would like to thank the GRG18 Scientific Organising Committee, GWIC
International Nuclear Information System (INIS)
Barbour, Julian; Foster, Brendan Z; Murchadha, Niall O
2002-01-01
We give a derivation of general relativity (GR) and the gauge principle that is novel in presupposing neither spacetime nor the relativity principle. We consider a class of actions defined on superspace (the space of Riemannian 3-geometries on a given bare manifold). It has two key properties. The first is symmetry under 3-diffeomorphisms. This is the only postulated symmetry, and it leads to a constraint linear in the canonical momenta. The second property is that the Lagrangian is constructed from a 'local' square root of an expression quadratic in the velocities. The square root is 'local' because it is taken before integration over 3-space. It gives rise to quadratic constraints that do not correspond to any symmetry and are not, in general, propagated by the Euler-Lagrange equations. Therefore these actions are internally inconsistent. However, one action of this form is well behaved: the Baierlein-Sharp-Wheeler (Baierlein R F, Sharp D and Wheeler J A 1962 Phys. Rev. 126 1864) reparametrization-invariant action for GR. From this viewpoint, spacetime symmetry is emergent. It appears as a 'hidden' symmetry in the (underdetermined) solutions of the Euler-Lagrange equations, without being manifestly coded into the action itself. In addition, propagation of the linear diffeomorphism constraint together with the quadratic square-root constraint acts as a striking selection mechanism beyond pure gravity. If a scalar field is included in the configuration space, it must have the same characteristic speed as gravity. Thus Einstein causality emerges. Finally, self-consistency requires that any 3-vector field must satisfy Einstein causality, the equivalence principle and, in addition, the Gauss constraint. Therefore we recover the standard (massless) Maxwell equations
Bell, D A
1986-01-01
Relational Databases explores the major advances in relational databases and provides a balanced analysis of the state of the art in relational databases. Topics covered include capture and analysis of data placement requirements; distributed relational database systems; data dependency manipulation in database schemata; and relational database support for computer graphics and computer aided design. This book is divided into three sections and begins with an overview of the theory and practice of distributed systems, using the example of INGRES from Relational Technology as illustration. The
DEFF Research Database (Denmark)
Due, P; Holstein, B; Lund, R
1999-01-01
We introduce a conceptual framework with social relations as the main concept and the structure and the function of social relations as subconcepts. The structure of social relations covers aspects of formal relations and social network. The function of social relations covers social support......, social anchorage and relational strain. We use this conceptual framework to describe social relations in the Danish population, with questionnaire data from the Danish Longitudinal Health Behaviour Study including a random sample of each of the age groups 25-, 50-, 60-and 70-year olds, N = 2......,011. The postal questionnaires were answered by a random sample in each of the age groups. The results show marked age and gender differences in both the structure and the function of social relations. The social network, measured as weekly contacts, weakens with age and so does instrumental support. Emotional...
DEFF Research Database (Denmark)
Madsen, Charlotte Øland; Rasmussen, Jørgen Gulddahl
2015-01-01
In this chapter, we emphasise what we have outlined as interesting areas of relational leadership and present some ideas on how to facilitate a broader understanding of relational leadership practice. This involves the interpretations that create connections between practice and ontology. We...... elaborate on how leadership in everyday situations can be understood from a relational perspective. The chapter will focus on outlining and inspiring the reader to co-operate with other people to develop further relational understandings of leading....
International Nuclear Information System (INIS)
Taylor, J.G.
1975-01-01
It is stated that the early chapters review special relativity from an elementary mathematical viewpoint, and include discussion of recent experiments which set out to test Einstein's predictions. The theory of relativity is then reformulated in more sophisticated mathematical language to show its relation to electro-magnetism, and to lay the foundation for more general viewpoints. The final chapter discusses in simple terms where activity in the field is currently centred, and where future interest lies. Chapter headings include: the constant speed of light; measuring time and distance; the Lorentz transformation (relativity of simultaneity, space-time and causality); relativistic kinematics (including - the Dopper effect); relativistic dynamics (including - nuclear binding energy, particle creation, electrodynamics); the structure of special relativity (including - the Lorentz group, the rotation group, elementary particle scattering); extensions of special relativity. (U.K.)
McGlinchey, S.
2017-01-01
A ‘Day 0’ introduction to International Relations for beginners. Written by a range of emerging and established experts, the chapters offer a broad sweep of the basic components of International Relations and the key contemporary issues that concern the discipline. The narrative arc forms a complete circle, taking readers from no knowledge to competency. The journey starts by examining how the international system was formed and ends by reflecting that International Relations is always adapti...
Shibata, Masaru
2016-01-01
This book is composed of two parts: First part describes basics in numerical relativity, that is, the formulations and methods for a solution of Einstein's equation and general relativistic matter field equations. This part will be helpful for beginners of numerical relativity who would like to understand the content of numerical relativity and its background. The second part focuses on the application of numerical relativity. A wide variety of scientific numerical results are introduced focusing in particular on the merger of binary neutron stars and black holes.
International Nuclear Information System (INIS)
1998-01-01
Public relations activities continued in a well-proved form of organizing plant visits and Information Centre off - site activities. Bohunice NPPs were visited by the number of 7294 visitors in 1997. A brief account of activities in public relations carried out by the Nuclear power plants Jaslovske Bohunice in 1997 is presented
Baker, John G.
2009-01-01
Recent advances in numerical relativity have fueled an explosion of progress in understanding the predictions of Einstein's theory of gravity, General Relativity, for the strong field dynamics, the gravitational radiation wave forms, and consequently the state of the remnant produced from the merger of compact binary objects. I will review recent results from the field, focusing on mergers of two black holes.
International Nuclear Information System (INIS)
Kenyon, I.R.
1990-01-01
General relativity is discussed in this book at a level appropriate to undergraduate students of physics and astronomy. It describes concepts and experimental results, and provides a succinct account of the formalism. A brief review of special relativity is followed by a discussion of the equivalence principle and its implications. Other topics covered include the concepts of curvature and the Schwarzschild metric, test of the general theory, black holes and their properties, gravitational radiation and methods for its detection, the impact of general relativity on cosmology, and the continuing search for a quantum theory of gravity. (author)
International Nuclear Information System (INIS)
French, A.P.
1982-01-01
This book is an introduction to special relativity theory. After a discussion of the limits of Newton's mechanics and the pecularities in the propagation of light the Lorentz transformation is introduced. Then the measurement of space and time intervals in the framework of relativity theory is considered. Thereafter the addition of velocities and acceleration are considered in this framework. Then relativistic kinematics of particle interactions are described. Then the four-dimensional calculus in space-time coordinates is introduced. Finally an introduction is given to the treatment of the electromagnetic field in the framework of relativity theory. Every chapter contains exercise problems with solutions. This book is suited for all students who want to get some fundamental knowledge about relativity theory. (HSI) [de
DEFF Research Database (Denmark)
Larsen, Mette Vinther; Rasmussen, Jørgen Gulddahl
2015-01-01
This first chapter presents the exploratory and curious approach to leading as relational processes – an approach that pervades the entire book. We explore leading from a perspective that emphasises the unpredictable challenges and triviality of everyday life, which we consider an interesting......, relevant and realistic way to examine leading. The chapter brings up a number of concepts and contexts as formulated by researchers within the field, and in this way seeks to construct a first understanding of relational leading....
Wolff, Phillip; Holmes, Kevin J
2011-05-01
The central question in research on linguistic relativity, or the Whorfian hypothesis, is whether people who speak different languages think differently. The recent resurgence of research on this question can be attributed, in part, to new insights about the ways in which language might impact thought. We identify seven categories of hypotheses about the possible effects of language on thought across a wide range of domains, including motion, color, spatial relations, number, and false belief understanding. While we do not find support for the idea that language determines the basic categories of thought or that it overwrites preexisting conceptual distinctions, we do find support for the proposal that language can make some distinctions difficult to avoid, as well as for the proposal that language can augment certain types of thinking. Further, we highlight recent evidence suggesting that language may induce a relatively schematic mode of thinking. Although the literature on linguistic relativity remains contentious, there is growing support for the view that language has a profound effect on thought. WIREs Cogni Sci 2011 2 253-265 DOI: 10.1002/wcs.104 For further resources related to this article, please visit the WIREs website. Copyright © 2010 John Wiley & Sons, Ltd.
International Nuclear Information System (INIS)
Gourgoulhon, Eric
2013-01-01
The author proposes a course on general relativity. He first presents a geometrical framework by addressing, presenting and discussion the following notions: the relativistic space-time, the metric tensor, Universe lines, observers, principle of equivalence and geodesics. In the next part, he addresses gravitational fields with spherical symmetry: presentation of the Schwarzschild metrics, radial light geodesics, gravitational spectral shift (Einstein effect), orbitals of material objects, photon trajectories. The next parts address the Einstein equation, black holes, gravitational waves, and cosmological solutions. Appendices propose a discussion of the relationship between relativity and GPS, some problems and their solutions, and Sage codes
Selleri, Franco
2015-01-01
Weak Relativity is an equivalent theory to Special Relativity according to Reichenbach’s definition, where the parameter epsilon equals to 0. It formulates a Neo-Lorentzian approach by replacing the Lorentz transformations with a new set named “Inertial Transformations”, thus explaining the Sagnac effect, the twin paradox and the trip from the future to the past in an easy and elegant way. The cosmic microwave background is suggested as a possible privileged reference system. Most importantly, being a theory based on experimental proofs, rather than mutual consensus, it offers a physical description of reality independent of the human observation.
Modification of piezoelectric vibratory gyroscope resonator parameters by feedback control
CSIR Research Space (South Africa)
Loveday, PW
1998-09-01
Full Text Available and labs with practical hands-on experience that will give them valuable experiences upon graduation. Another topic Dr. Rogers has made a priority is the introduction of engineering concepts into the science curriculum in the elementary schools. His belief... vibration modes have the same natural frequency, Manuscript received September 4, 1997; accepted December 18, 1997. P. W. Loveday is with Sensor Systems, Division of Material Science and Technology, CSIR, Pretoria, South Africa (e-mail: ploveday...
Analysis of Acousto-Optic Errors in Laser Gyroscopes.
1982-12-01
2 2 Sagnac’s Interferometer ................................ 4 3 Harress ’ Prism Ring.................................... 5 4...years before Sagnac’s experiment, Harress , a German graduate student formed a ring of partially reflecting prisms to measure the dispersive properties of...glass (Figure 3). Harress noticed a fringe shift when he rotated the ring, and he assumed that the shift was caused by the *dragging" of the light
Durell, Clement V
1962-01-01
Concise and practical, this text by a renowned teacher sketches the mathematical background essential to understanding the fundamentals of relativity theory. Subjects include the velocity of light, measurement of time and distance, and properties of mass and momentum, with numerous diagrams, formulas, and examples, plus exercises and solutions. 1960 edition.
DHILLON, Amrita; MERTENS, Jean-François
1993-01-01
In a framework of preferences over lotteries, we show that an axiom system consisting of weakned versions of Arrow’s axioms has a unique solution. “Relative Utilitarianism” consists of first normalizing individual von Neumann-Morgenstern utilities between 0 and 1 and then summing them.
African Journals Online (AJOL)
Adele
the vascular space and the remainder of the extracellular fluid. (ECF) and intracellular ... diuretic therapy are likely to have a relative volume deficiency. Normovolaemia and .... and it is likely that alternative forms of assessment of this crucial measure will be ... necrosis factor and Interleukins1–6, histamine and serotonin.
Straumann, Norbert
2013-01-01
This book provides a completely revised and expanded version of the previous classic edition ‘General Relativity and Relativistic Astrophysics’. In Part I the foundations of general relativity are thoroughly developed, while Part II is devoted to tests of general relativity and many of its applications. Binary pulsars – our best laboratories for general relativity – are studied in considerable detail. An introduction to gravitational lensing theory is included as well, so as to make the current literature on the subject accessible to readers. Considerable attention is devoted to the study of compact objects, especially to black holes. This includes a detailed derivation of the Kerr solution, Israel’s proof of his uniqueness theorem, and a derivation of the basic laws of black hole physics. Part II ends with Witten’s proof of the positive energy theorem, which is presented in detail, together with the required tools on spin structures and spinor analysis. In Part III, all of the differential geomet...
International Nuclear Information System (INIS)
Anon.
2008-01-01
Concerning international relations, the different meetings in the field of nuclear safety are reported (Western european nuclear regulator association or Wenra, Nea, IAEA, northern dimension environmental partnership or N.D.E.P., nuclear safety and security group or N.S.S.G., international nuclear regulators association or I.N.R.A.). (N.C.)
Laser Gravitational-wave Antenna in Geodetic Orbit: LAGRANGE and LAGRANGE 2020
International Nuclear Information System (INIS)
Buchman, S.; Balakrishnan, K.; Byer, R.L.; Cutler, G.D.; Debra, D.B.; Hultgren, E.; Lantz, B.; Lipa, J.A.; Saraf, S.; Zoellner, A.; Conklin, J.W.; Aguero, V.; Williams, S.D.; Alfauwaz, A.; Aljadaan, A.; Almajed, M.; Altwaijry, H.; Al Saud, T.; Bower, K.; Costello, B.; Hooper, K.; Klavins, A.; Palmer, A.; Plante, B.; Schaechter, D.; Shu, K.L.; Smith, E.; Tenerelli, D.; Vanbezooijen, R.; Vasudevan, G.; Faied, D.M.; Foster, C.; Genova, A.L.; Sanchez, H.S.; Worden, S.P.; Hanson, J.
2014-01-01
We describe a Laser Gravitational-wave Antenna in Geodic Orbit design called LAGRANGE that maintains all important LISA science at about half the cost of the original LISA mission and with reduced technical risk. It consists of 3 drag-free spacecraft (SC) in a geocentric formation. Fixed antennas allow continuous contact with the Earth, solving the problem of communications bandwidth and latency. A 70 mm diameter sphere with a 35 mm gap to its enclosure serves as the single inertial reference per SC, operating in 'true' drag-free mode (no test mass forcing). Other advantages are: a single caging design based on the DISCOS 1972 drag-free mission, an all optical read-out with pm fine and nm coarse sensors, and the extreme technology heritage from the Honeywell gyroscopes, and the DISCOS and Gravity Probe B drag-free sensors. An interferometric Measurement System, designed with reflective optics and a highly stabilized frequency standard, performs the ranging between test masses and requires a single optical bench with one laser per SC. Two 20 cm diameter telescope per SC, each with infield pointing, incorporate novel technology developed for advanced optical systems by Lockheed Martin, who also designed the SC based on a multi-flight proven bus structure. Additional technological advancements include include updated propulsion technology, improved thermal control, and a UV-LED charge management system. LAGRANGE subsystems are designed to be scalable and modular, making them interchangeable with those of LISA or other gravitational science missions. We plan to space qualify critical technologies on small and nano satellite flights, with the first launch (UV-LED Sat) in 2013. We further propose a relaxed performance version of LAGRANGE to be flown before 2020 at one quarter the cost of LISA. The requirements on the drag-free sensors and interferometers are relaxed by factors of 10-100 while the core science, super massive black hole (MBH) mergers, is maintained
LAGRANGE: LAser GRavitational-wave ANtenna in GEodetic Orbit
Buchman, S.; Conklin, J. W.; Balakrishnan, K.; Aguero, V.; Alfauwaz, A.; Aljadaan, A.; Almajed, M.; Altwaijry, H.; Saud, T. A.; Byer, R. L.; Bower, K.; Costello, B.; Cutler, G. D.; DeBra, D. B.; Faied, D. M.; Foster, C.; Genova, A. L.; Hanson, J.; Hooper, K.; Hultgren, E.; Klavins, A.; Lantz, B.; Lipa, J. A.; Palmer, A.; Plante, B.; Sanchez, H. S.; Saraf, S.; Schaechter, D.; Shu, K.; Smith, E.; Tenerelli, D.; Vanbezooijen, R.; Vasudevan, G.; Williams, S. D.; Worden, S. P.; Zhou, J.; Zoellner, A.
2013-01-01
We describe a new space gravitational wave observatory design called LAG-RANGE that maintains all important LISA science at about half the cost and with reduced technical risk. It consists of three drag-free spacecraft in a geocentric formation. Fixed antennas allow continuous contact with the Earth, solving the problem of communications bandwidth and latency. A 70 mm diameter sphere with a 35 mm gap to its enclosure serves as the single inertial reference per spacecraft, operating in “true” drag-free mode (no test mass forcing). Other advantages are: a simple caging design based on the DISCOS 1972 drag-free mission, an all optical read-out with pm fine and nm coarse sensors, and the extensive technology heritage from the Honeywell gyroscopes, and the DISCOS and Gravity Probe B drag-free sensors. An Interferometric Measurement System, designed with reflective optics and a highly stabilized frequency standard, performs the ranging between test masses and requires a single optical bench with one laser per spacecraft. Two 20 cm diameter telescopes per spacecraft, each with infield pointing, incorporate novel technology developed for advanced optical systems by Lockheed Martin, who also designed the spacecraft based on a multi-flight proven bus structure. Additional technological advancements include updated drag-free propulsion, thermal control, charge management systems, and materials. LAGRANGE subsystems are designed to be scalable and modular, making them interchangeable with those of LISA or other gravitational science missions. We plan to space qualify critical technologies on small and nano satellite flights, with the first launch (UV-LED Sat) in 2013.
DEFF Research Database (Denmark)
Reeh, Henrik
2018-01-01
in a scholarly institution (element #3), as well as the certified PhD scholar (element #4) and the architectural profession, notably its labour market (element #5). This first layer outlines the contemporary context which allows architectural research to take place in a dynamic relationship to doctoral education...... a human and institutional development going on since around 1990 when the present PhD institution was first implemented in Denmark. To be sure, the model is centred around the PhD dissertation (element #1). But it involves four more components: the PhD candidate (element #2), his or her supervisor...... and interrelated fields in which history, place, and sound come to emphasize architecture’s relational qualities rather than the apparent three-dimensional solidity of constructed space. A third layer of relational architecture is at stake in the professional experiences after the defence of the authors...
DEFF Research Database (Denmark)
This is the textbook for the Open University module International Relations: Continuity and Change in Global Politics. Instead of leading with a succession of theoretical 'isms', the module structures its presentation of the subject around six teaching ‘blocks’, each of which explores a dilemma...... • Block 6: Continuity or change in global politics? Each block introduces new IR theories through discussions of the substantive dilemmas and adds in a layered way levels of analysis and conceptual complexity......., or dimension of variation. The dilemmas in question were chosen for the way they capture key themes in the field of International Studies (IR) as well as central aspects of the ‘international’ itself (ir). The six Blocks are: • Block 1: Co-operation or conflict? Introducing international relations • Block 2...
Schmidt, Gunther
2018-01-01
This book introduces and develops new algebraic methods to work with relations, often conceived as Boolean matrices, and applies them to topology. Although these objects mirror the matrices that appear throughout mathematics, numerics, statistics, engineering, and elsewhere, the methods used to work with them are much less well known. In addition to their purely topological applications, the volume also details how the techniques may be successfully applied to spatial reasoning and to logics of computer science. Topologists will find several familiar concepts presented in a concise and algebraically manipulable form which is far more condensed than usual, but visualized via represented relations and thus readily graspable. This approach also offers the possibility of handling topological problems using proof assistants.
International Nuclear Information System (INIS)
Piran, T.
1982-01-01
There are many recent developments in numerical relativity, but there remain important unsolved theoretical and practical problems. The author reviews existing numerical approaches to solution of the exact Einstein equations. A framework for classification and comparison of different numerical schemes is presented. Recent numerical codes are compared using this framework. The discussion focuses on new developments and on currently open questions, excluding a review of numerical techniques. (Auth.)
International Nuclear Information System (INIS)
1996-01-01
At Nuclear Regulatory Authority of the Slovak Republic (NRA SR), the public relations belongs to the secretariat of the Chairman, and are a part of the policy of carefully planned and purposeful efforts to establish mutual relations between the authority and the public. A spokesmen of NRA SR is in charge of the public relations. The spokesman is ready, without a useless filibuster and based on a particular requirement, to inform governmental bodies, other national bodies and organizations, embassies and international organizations, the public and news media in case of an event at a nuclear installation. To provide for communications activities, NRA SR constructed and opened the Information centre with a particular equipment in autumn 1995, that has already started communications with some dailies, broadcasting, television and Press Agency SR. It has been envisaged that there will be press conferences held in the Information centre a few times a year, or NRA SR senior staff may be interviewed here on extraordinary events at NPPs, or on some other important occasions in NRA SR. In 1995, NRA Sr issued the Annual report in a few variants - each suitable for different use - on NRA SR activities and nuclear safety of Slovak nuclear power plants as of 1994. The NRA SR's Bulletin has started to be published with periodicity of 3 times a year, focusing on NRA SR activities both in Slovakia and abroad. NRA SR Information centre provides foreign visitors with independent propagation and information materials about the issue of nuclear safety enhancement at operational Slovak NPPs. Furthermore, the Information centre provides both the NRA SR's residences in Bratislava and Trnava with daily press monitoring of topical news
DEFF Research Database (Denmark)
Smith, Aja
This thesis explores the phenomenon of horse-assisted leadership training and the manners, in which the training relations between horses, managers and facilitators were entangled with perceptions of, what “proper sociality” entailed and felt like in contemporary Danish society. The study...... is positioned at the intersection of anthropology and consumer culture research and is based upon 15 months of ethnographic fieldwork in fields, offices and conference rooms throughout Denmark in 2012 and 2013 as well as reading of emic literature and marketing material. The main argument of the thesis is...
Mould, Richard A
1994-01-01
This comprehensive textbook develops in a logical and coherent way both the formalism and the physical ideas of special and general relativity. Part one focuses on the special theory and begins with the study of relativistic kinematics from three points of view. Part two begins with a chapter introducing differential geometry. Subsequent chapters cover: rotation, the electromagnetic field, and material media. A second chapter on differential geometry provides the background for Einstein's gravitational-field equation and Schwarzschild's solution. The book is aimed at advanced undergraduates and beginning graduate students in physics or astrophysics.
Relatives and Relations in Paluai’
DEFF Research Database (Denmark)
Schokkin, Dineke; Otto, Ton
2017-01-01
This paper discusses the expression of kinship in Paluai (Baluan-Pam, ISO 639-3: blq), an Oceanic language spoken on Baluan Island, Manus Province, Papua New Guinea. Based on data gathered during extensive fieldwork, the authors first consider the formal characteristics of nominal possessive cons...... of birth order terms, which are a relatively rare phenomenon, and the partial replacement of the system by terms from the creole language Tok Pisin....
Faraoni, Valerio
2013-01-01
This book offers an essential bridge between college-level introductions and advanced graduate-level books on special relativity. It begins at an elementary level, presenting and discussing the basic concepts normally covered in college-level works, including the Lorentz transformation. Subsequent chapters introduce the four-dimensional worldview implied by the Lorentz transformations, mixing time and space coordinates, before continuing on to the formalism of tensors, a topic usually avoided in lower-level courses. The book’s second half addresses a number of essential points, including the concept of causality; the equivalence between mass and energy, including applications; relativistic optics; and measurements and matter in Minkowski spacetime. The closing chapters focus on the energy-momentum tensor of a continuous distribution of mass-energy and its covariant conservation; angular momentum; a discussion of the scalar field of perfect fluids and the Maxwell field; and general coordinates. Every chapter...
International Nuclear Information System (INIS)
O'Neil, C.
1997-01-01
The interaction of the oil and gas companies with the Northern communities regarding drilling activities was an important aspect of oil and gas operations conducted in the Beaufort Sea. During the 1960s the industry and aboriginal people basically ignored each other. Later, the industry put more emphasis on community consultation until finally two-way communication was established. Respect for the land and the environment were very important to aboriginal people who depended on the land and its resources for their traditional way of life. Community relations policies by the various companies involved in the area, and the impact they have had on their respective communities were recounted. Not all efforts were successful, however, the companies and the communities learned from their experiences, and by the time operations ceased, the communities seemed to be more appreciative of the ways they were being treated by the oil companies. 22 figs
Nakamura, T
1993-01-01
In GR13 we heard many reports on recent. progress as well as future plans of detection of gravitational waves. According to these reports (see the report of the workshop on the detection of gravitational waves by Paik in this volume), it is highly probable that the sensitivity of detectors such as laser interferometers and ultra low temperature resonant bars will reach the level of h ~ 10—21 by 1998. in this level we may expect the detection of the gravitational waves from astrophysical sources such as coalescing binary neutron stars once a year or so. Therefore the progress in numerical relativity is urgently required to predict the wave pattern and amplitude of the gravitational waves from realistic astrophysical sources. The time left for numerical relativists is only six years or so although there are so many difﬁculties in principle as well as in practice.
Directory of Open Access Journals (Sweden)
Naif M. Alsubaie
2017-09-01
Full Text Available This paper introduces a new method which facilitate the use of smartphones as a handheld low-cost mobile mapping system (MMS. Smartphones are becoming more sophisticated and smarter and are quickly closing the gap between computers and portable tablet devices. The current generation of smartphones are equipped with low-cost GPS receivers, high-resolution digital cameras, and micro-electro mechanical systems (MEMS-based navigation sensors (e.g., accelerometers, gyroscopes, magnetic compasses, and barometers. These sensors are in fact the essential components for a MMS. However, smartphone navigation sensors suffer from the poor accuracy of global navigation satellite System (GNSS, accumulated drift, and high signal noise. These issues affect the accuracy of the initial Exterior Orientation Parameters (EOPs that are inputted into the bundle adjustment algorithm, which then produces inaccurate 3D mapping solutions. This paper proposes new methodologies for increasing the accuracy of direct geo-referencing of smartphones using relative orientation and smartphone motion sensor measurements as well as integrating geometric scene constraints into free network bundle adjustment. The new methodologies incorporate fusing the relative orientations of the captured images and their corresponding motion sensor measurements to improve the initial EOPs. Then, the geometric features (e.g., horizontal and vertical linear lines visible in each image are extracted and used as constraints in the bundle adjustment procedure which correct the relative position and orientation of the 3D mapping solution.
International Nuclear Information System (INIS)
Anon.
2009-01-01
The French nuclear safety authority (A.S.N.) has participated at different meeting in European Union as nuclear decommissioning assistance programme(N.D.A.P.), Regulatory assistance management group (R.A.M.G.) and Instrument for nuclear safety cooperation (I.N.S.C.). The members of Western European nuclear regulator association (W.E.N.R.A.) met and discussed about the future of W.E.N.R.A. and its representativeness and its cooperation with European nuclear safety regulator group (E.N.S.R.E.G.) and head of European radiation control authorities (H.E.R.C.A.). About International relations it is to noticed a meeting at the invitation of IAEA to discuss about the possibility to resort to the Ines scale for medical events. An audit mission under the IAEA aegis stood at Fessenheim, O.S.A.R.T. for operational safety review team. Two years and a half passed by between the audit mission Integrated regulatory review service (I.R.S.S.) welcome by A.S.N. in november 2006 and the audit mission follow up in 2009, 12 experts from 11 different countries and coordinated by three representatives of IAEA worked, the conclusions were that 90% of recommendations made to A.S.N. in 2006 were treated in a satisfying way; the evaluation gives three new recommendations, 7 new suggestions and 11 new correct practices. A meeting of the commission on safety standards (C.S.S.) stood in april 2009. Some others meeting are to be noticed: nuclear safety and security group (N.S.S.G.), expert group on nuclear and radiation safety (E.G.N.R.S.) instituted by the council of the Baltic sea states (C.B.S.S.) treats data exchange on the national networks of dose rates and surveillance of radioactivity in air. International nuclear regulator association (I.N.R.A.) held its first meeting in april 2009 at Seoul (Korea). Bilateral relations with Poland, Italy, Ukraine and Germany planed cooperation or information exchange in the field of nuclear safety. Participation to conference in Usa, meetings with United
Constraints on perturbative f(R) gravity via neutron stars
Energy Technology Data Exchange (ETDEWEB)
Arapoğlu, Savaş; Ekşi, K. Yavuz [İstanbul Technical University, Faculty of Science and Letters, Physics Engineering Department, Maslak 34469, İstanbul (Turkey); Deliduman, Cemsinan, E-mail: arapoglu@itu.edu.tr, E-mail: cemsinan@msgsu.edu.tr, E-mail: eksi@itu.edu.tr [Mimar Sinan Fine Arts University, Department of Physics, Beşiktaş 34349, İstanbul (Turkey)
2011-07-01
We study the structure of neutron stars in perturbative f(R) gravity models with realistic equations of state. We obtain mass-radius relations in a gravity model of the form f(R) = R+αR{sup 2}. We find that deviations from the results of general relativity, comparable to the variations due to using different equations of state (EoS'), are induced for |α| ∼ 10{sup 9} cm{sup 2}. Some of the soft EoS' that are excluded within the framework of general relativity can be reconciled with the 2 solar mass neutron star recently observed for certain values of α within this range. For some of the EoS' we find that a new solution branch, which allows highly massive neutron stars, exists for values of α greater than a few 10{sup 9} cm{sup 2}. We find constraints on α for a variety of EoS' using the recent observational constraints on the mass-radius relation. These are all 5 orders of magnitude smaller than the recent constraint obtained via Gravity Probe B for this gravity model. The associated length scale √(alpha)approx 10{sup 5} cm is only an order of magnitude smaller than the typical radius of a neutron star, the probe used in this test. This implies that real deviations from general relativity can be even smaller.
Social relations: network, support and relational strain
DEFF Research Database (Denmark)
Due, P; Holstein, B; Lund, Rikke
1999-01-01
We introduce a conceptual framework with social relations as the main concept and the structure and the function of social relations as subconcepts. The structure of social relations covers aspects of formal relations and social network. The function of social relations covers social support......,011. The postal questionnaires were answered by a random sample in each of the age groups. The results show marked age and gender differences in both the structure and the function of social relations. The social network, measured as weekly contacts, weakens with age and so does instrumental support. Emotional...... support is unrelated to this decline in contact frequency and appears to be at the same level for younger and older individuals. Relational strain, measured as conflicts, declines with age for all kinds of social relations. The weakening of the social network with age does not seem to affect the level...
Incorporating Relation Paths in Neural Relation Extraction
Zeng, Wenyuan; Lin, Yankai; Liu, Zhiyuan; Sun, Maosong
2016-01-01
Distantly supervised relation extraction has been widely used to find novel relational facts from plain text. To predict the relation between a pair of two target entities, existing methods solely rely on those direct sentences containing both entities. In fact, there are also many sentences containing only one of the target entities, which provide rich and useful information for relation extraction. To address this issue, we build inference chains between two target entities via intermediate...
Visualizing relativity: The OpenRelativity project
Sherin, Zachary W.; Cheu, Ryan; Tan, Philip; Kortemeyer, Gerd
2016-05-01
We present OpenRelativity, an open-source toolkit to simulate effects of special relativity within the popular Unity game engine. Intended for game developers, educators, and anyone interested in physics, OpenRelativity can help people create, test, and share experiments to explore the effects of special relativity. We describe the underlying physics and some of the implementation details of this toolset with the hope that engaging games and interactive relativistic "laboratory" experiments might be implemented.
... The Marfan Foundation Marfan & Related Disorders What is Marfan Syndrome? What are Related Disorders? What are the Signs? ... Contact Us Donate Marfan & Related Disorders What is Marfan Syndrome? What are Related Disorders? What are the Signs? ...
... to learn. Search form Search Tests related to pregnancy You are here Home Testing & Services Testing for ... to Genetic Counseling . What Are Tests Related to Pregnancy? Pregnancy related testing is done before or during ...
Pioneers as Relational Subjects? Probing Relationality as ...
African Journals Online (AJOL)
relational engagement roles in driving the energy transition, as described on their website. ... He comments, 'In Japan, they call it Viking leadership,' .... island, such as the mayor, representatives of different business, leading employees at the.
Public Relations and Marketing.
Savage, Daniel D.
1987-01-01
Urges community colleges to adopt pro-active public relations strategies. Examines the role of the public information officer in such areas as coordination of public relations and marketing activities, relations with media, and the development of a comprehensive public relations plan. (AYC)
Functional Programming With Relations
Hutton, Graham
1991-01-01
While programming in a relational framework has much to offer over the functional style in terms of expressiveness, computing with relations is less efficient, and more semantically troublesome. In this paper we propose a novel blend of the functional and relational styles. We identify a class of "causal relations", which inherit some of the bi-directionality properties of relations, but retain the efficiency and semantic foundations of the functional style.
Introduction to relation algebras relation algebras
Givant, Steven
2017-01-01
The first volume of a pair that charts relation algebras from novice to expert level, this text offers a comprehensive grounding for readers new to the topic. Upon completing this introduction, mathematics students may delve into areas of active research by progressing to the second volume, Advanced Topics in Relation Algebras; computer scientists, philosophers, and beyond will be equipped to apply these tools in their own field. The careful presentation establishes first the arithmetic of relation algebras, providing ample motivation and examples, then proceeds primarily on the basis of algebraic constructions: subalgebras, homomorphisms, quotient algebras, and direct products. Each chapter ends with a historical section and a substantial number of exercises. The only formal prerequisite is a background in abstract algebra and some mathematical maturity, though the reader will also benefit from familiarity with Boolean algebra and naïve set theory. The measured pace and outstanding clarity are particularly ...
Theoretical general relativity: 1979
International Nuclear Information System (INIS)
Bergmann, O.
1979-01-01
The metric and field equations of Einstein's general relativity theory are written down. Solutions to the equations are discussed. Connection is made between relativity theory and elementary particle theory. Possibilities for a unified field theory are considered
Gardner, Martin
2012-01-01
Since the publication of Einstein's Special Theory of Relativity in 1905, the discovery of such astronomical phenomena as quasars, pulsars, and black holes - all intimately connected to relativity - has provoked a tremendous upsurge of interest in the subject. This volume, a revised version of Martin Gardner's earlier Relativity for the Million, brings this fascinating topic up to date. Witty, perceptive, and easily accessible to the general reader, it is one of the clearest and most entertaining introductions to relativity ever written.
International Nuclear Information System (INIS)
Pal, Palash B
2003-01-01
We deduce the most general space-time transformation laws consistent with the principle of relativity. Thus, our result contains the results of both Galilean and Einsteinian relativity. The velocity addition law comes as a by-product of this analysis. We also argue why Galilean and Einsteinian versions are the only possible embodiments of the principle of relativity
2001-09-01
This report is designed as a guide for those involved in labor relations in the transit industry. It begins with a history of transit labor relations. The economic, political, and legal environment of transit relations is then discussed. A section fo...
Kaufmann, William J
1973-01-01
The foundations of gravitational theory ; the birth of relativity theory ; the foundations of general relativity ; experimental tests of relativity ; the meaning of the redshift ; the black hole ; wormholes and white holes ; galaxies and quasars ; gravitational waves ; the shape of the Universe ; the creation of the Universe.
DEFF Research Database (Denmark)
Beauquier, Maxime; Schürmann, Carsten
2011-01-01
In this paper, we present a model based on relations for bigraphical reactive system [Milner09]. Its defining characteristics are that validity and reaction relations are captured as traces in a multi-set rewriting system. The relational model is derived from Milner's graphical definition...
Rayleigh reciprocity relations: Applications
International Nuclear Information System (INIS)
Lin Ju; Li Xiao-Lei; Wang Ning
2016-01-01
Classical reciprocity relations have wide applications in acoustics, from field representation to generalized optical theorem. In this paper we introduce our recent results on the applications and generalization of classical Rayleigh reciprocity relation: higher derivative reciprocity relations as a generalization of the classical one and a theoretical proof on the Green’s function retrieval from volume noises. (special topic)
International Nuclear Information System (INIS)
Lawden, D.F.
1985-01-01
The book on elements of relativity theory is intended for final year school students or as an early university course in mathematical physics. Special principle of relativity, lorentz transformation, velocity transformations, relativistic mechanics, and general theory of relativity, are all discussed. (U.K.)
Relativity theory and gravitation
International Nuclear Information System (INIS)
Bondi, H.
1986-01-01
The paper on relativity theory and gravitation is presented as a preface to the first of the articles submitted to the Journal on general relativity. Newtonian gravitation and and observation, relativity, and the sources of the gravitational field, are all discussed. (UK)
Decreasing Relative Risk Premium
DEFF Research Database (Denmark)
Hansen, Frank
relative risk premium in the small implies decreasing relative risk premium in the large, and decreasing relative risk premium everywhere implies risk aversion. We finally show that preferences with decreasing relative risk premium may be equivalently expressed in terms of certain preferences on risky......We consider the risk premium demanded by a decision maker with wealth x in order to be indifferent between obtaining a new level of wealth y1 with certainty, or to participate in a lottery which either results in unchanged present wealth or a level of wealth y2 > y1. We define the relative risk...... premium as the quotient between the risk premium and the increase in wealth y1–x which the decision maker puts on the line by choosing the lottery in place of receiving y1 with certainty. We study preferences such that the relative risk premium is a decreasing function of present wealth, and we determine...
Relational aggression in marriage.
Carroll, Jason S; Nelson, David A; Yorgason, Jeremy B; Harper, James M; Ashton, Ruth Hagmann; Jensen, Alexander C
2010-01-01
Drawing from developmental theories of relational aggression, this article reports on a study designed to identify if spouses use relationally aggressive tactics when dealing with conflict in their marriage and the association of these behaviors with marital outcomes. Using a sample of 336 married couples (672 spouses), results revealed that the majority of couples reported that relationally aggressive behaviors, such as social sabotage and love withdrawal, were a part of their marital dynamics, at least to some degree. Gender comparisons of partner reports of their spouse's behavior revealed that wives were significantly more likely to be relationally aggressive than husbands. Structural equation modeling demonstrated that relational aggression is associated with lower levels of marital quality and greater marital instability for both husbands and wives. Implications are drawn for the use of relational aggression theory in the future study of couple conflict and marital aggression. (c) 2010 Wiley-Liss, Inc.
Bulk optic Sagnac interferometer for tests of general relativity
International Nuclear Information System (INIS)
Ranganathan, D.; Mehta, C.L.
1986-01-01
Ring laser and Sagnac interferometer gyroscopes have been suggested for a possible experiment to test metric theories of gravity. As emphasized in recent reviews, neither ring lasers nor fiber gyroscopes seem to provide the required accuracy. The same appears to be true of passive cavity resonators or nonlinear variants. The primary problem with fiber Sagnac interferometers is that the permissible power before onset or nonlinearities is quite limited (10-100 mW). Thus the SNR possible is also limited. To overcome this limitation, the authors suggest use of a bulk optic device. Specifically, the author' suggest the use of a silica block with a square cross section. Each of its faces is polished to form a segment of a sphere whose center is at the center of the opposite face. Rays originating at the center of a face and incident on the next adjacent face near its center are totally internally reflected and focused on the center of the third face in sequence. Thus the light rotates about the cavity before coming back to the point of incidence. If a light beam is introduced slightly off-axis in such an arrangement, it must complete many rotations before coming back to its starting point. Such off-axis delay lines have been used in laser gravitational wave detectors. A similar resonator has been used by another group. In the authors' configuration, the internal reflections minimize reflection and scattering losses. The spherical surfaces can be figured extremely accurately. The system is achromatic, and thus multifrequency operation to eliminate cavity drifts is possible. A model analysis for this cavity is presented including estimates of the error due to Rayleigh scattering. Generalization of this configuration to include cavities with a greater number of faces and their advantages are discussed
Strategi Komunikasi Public Relations
Artis, Artis
2011-01-01
Living man in interrelates society. Relationship among human being done by gets communication so man one by another one mutually understand and influence regard for the benefit, it that always been practiced by Public Relations( liaison) in a governance and also firm institute to reach to the effect which ices. The institute of Public Relations declares for,”Public Relations is overall effort which be passed off by design and berkesenambungan in order to creates and pet keenness and mutual un...
Ofer H. Azar
2005-01-01
The article presents a theory that I denote “Relative Thinking Theory,” which claims that people consider relative differences and not only absolute differences when making various economics decisions, even in those cases where the rational model dictates that people should consider only absolute differences. The article reviews experimental evidence for this behavior, summarizing briefly several experiments I conducted, as well as some earlier related literature. It then discusses how we can...
Infeld, Leopold
1960-01-01
Motion and Relativity focuses on the methodologies, solutions, and approaches involved in the study of motion and relativity, including the general relativity theory, gravitation, and approximation.The publication first offers information on notation and gravitational interaction and the general theory of motion. Discussions focus on the notation of the general relativity theory, field values on the world-lines, general statement of the physical problem, Newton's theory of gravitation, and forms for the equation of motion of the second kind. The text then takes a look at the approximation meth
Directory of Open Access Journals (Sweden)
Bajić Milan
2010-01-01
Full Text Available The aim of this paper is the analysis of different forms of PR implementation and research its relation with ethics in practice. 'Public relations' is the every-day term that represents the job that is widely used in all aspects of life and work in today's society. Public relations represent a specific form of communication that has a particular application in society. Public relations involve focusing on a public aspect of organization with the aim of building a positive attitude and image. Image of public relations as a profession is often unfairly negative, and the reason for this is unprofessional and unethical relation of individuals towards their profession. In practice ethics in public relations is often considered to be an oxymoron. Ethical thinking of experts in public relations goes from Biblical attitude 'all you want people to do to you, do even so to them' (Matthew 7:12to professional loyalty to organization they work for. Because of unethical appearance it is important to set the rules, in the form of codex by which the public relations professionals will set their behaviors. .
Gaining Relational Competitive Advantages
DEFF Research Database (Denmark)
Hu, Yimei; Zhang, Si; Li, Jizhen
2015-01-01
Establishing strategic technological partnerships (STPs) with foreign partners is an increasingly studied topic within the innovation management literature. Partnering firms can jointly create sources of relational competitive advantage. Chinese firms often lack research and development (R......&D) capabilities but are increasingly becoming preferred technological partners for transnational corporations. We investigate an STP between a Scandinavian and a Chinese firm and try to explore how to gain relational competitive advantage by focusing on its two essential stages: relational rent generation...... and appropriation. Based on an explorative case study, we develop a conceptual framework that consists of process, organizational alliance factors, and coordination modes that we propose lead to relational competitive advantage....
Models as Relational Categories
Kokkonen, Tommi
2017-11-01
Model-based learning (MBL) has an established position within science education. It has been found to enhance conceptual understanding and provide a way for engaging students in authentic scientific activity. Despite ample research, few studies have examined the cognitive processes regarding learning scientific concepts within MBL. On the other hand, recent research within cognitive science has examined the learning of so-called relational categories. Relational categories are categories whose membership is determined on the basis of the common relational structure. In this theoretical paper, I argue that viewing models as relational categories provides a well-motivated cognitive basis for MBL. I discuss the different roles of models and modeling within MBL (using ready-made models, constructive modeling, and generative modeling) and discern the related cognitive aspects brought forward by the reinterpretation of models as relational categories. I will argue that relational knowledge is vital in learning novel models and in the transfer of learning. Moreover, relational knowledge underlies the coherent, hierarchical knowledge of experts. Lastly, I will examine how the format of external representations may affect the learning of models and the relevant relations. The nature of the learning mechanisms underlying students' mental representations of models is an interesting open question to be examined. Furthermore, the ways in which the expert-like knowledge develops and how to best support it is in need of more research. The discussion and conceptualization of models as relational categories allows discerning students' mental representations of models in terms of evolving relational structures in greater detail than previously done.
Relational Perspectives on Leading
DEFF Research Database (Denmark)
Relational Perspectives on Leading discusses leadership from a relational and social constructionism perspective as practiced on an everyday basis between people. The book pursues a fast growing, practice-based approach - particularly within the Anglo-Saxon parts of the world - to organization...
DEFF Research Database (Denmark)
Seeberg, Peter
2018-01-01
-related foreign policy considerations: the ENP Action Plans (APs) ‘will draw on a common set of principles but will be differentiated, reflecting the existing state of relations with each country, its needs and capacities, as well as common interests’ (Commission of the European Communities 2004). In the Mashreq...
DEFF Research Database (Denmark)
Jensen de López, Kristine M.; Sundahl Olsen, Lone; Chondrigianni, V.
2014-01-01
This study examines the comprehension and production of subject and object relative clauses (SRCs, ORCs) by children with Specific Language Impairment (SLI) and their typically developing (TD) peers. The purpose is to investigate whether relative clauses are problematic for Danish children with S...... with the assignment of thematic roles rather than with the structural make-up of RCs....
Scully, Maura King
2010-01-01
Increasingly today, with the growing and sophisticated skill set alumni professionals need to get the job done, alumni relations has become a destination career rather than a stop along the way. Modern alumni relations is "so much more than homecoming and punch-and-cookie receptions." It's marketing, volunteer management, and social networking. To…
... Share this! EmergencyCareForYou » Emergency 101 » Heat-Related Illnesses Heat-Related Illnesses Dr. Glenn Mitchell , Emergency physician at ... about heat cramps and heat stroke and exhaustion. Heat Cramps Symptoms include muscle spasms, usually in the ...
Full Text Available ... Share this! EmergencyCareForYou » Emergency 101 » Heat-Related Illnesses Heat-Related Illnesses Dr. Glenn Mitchell , Emergency physician at ... about heat cramps and heat stroke and exhaustion. Heat Cramps Symptoms include muscle spasms, usually in the ...
Teaching Mediated Public Relations.
Kent, Michael L.
2001-01-01
Discusses approaches to teaching a mediated public relations course, emphasizing the World Wide Web. Outlines five course objectives, assignments and activities, evaluation, texts, and lecture topics. Argues that students mastering these course objectives will understand ethical issues relating to media use, using mediated technology in public…
Measuring Relational Reasoning
Alexander, Patricia A.; Dumas, Denis; Grossnickle, Emily M.; List, Alexandra; Firetto, Carla M.
2016-01-01
Relational reasoning is the foundational cognitive ability to discern meaningful patterns within an informational stream, but its reliable and valid measurement remains problematic. In this investigation, the measurement of relational reasoning unfolded in three stages. Stage 1 entailed the establishment of a research-based conceptualization of…
Braeken, Johan; Mulder, Joris; Wood, Stephen
2015-01-01
Assessing the relative importance of predictors has been of historical importance in a variety of disciplines including management, medicine, economics, and psychology. When approaching hypotheses on the relative ordering of the magnitude of predicted effects (e.g., the effects of discrimination
Methods of numerical relativity
International Nuclear Information System (INIS)
Piran, T.
1983-01-01
Numerical Relativity is an alternative to analytical methods for obtaining solutions for Einstein equations. Numerical methods are particularly useful for studying generation of gravitational radiation by potential strong sources. The author reviews the analytical background, the numerical analysis aspects and techniques and some of the difficulties involved in numerical relativity. (Auth.)
Relational Processing Following Stroke
Andrews, Glenda; Halford, Graeme S.; Shum, David; Maujean, Annick; Chappell, Mark; Birney, Damian
2013-01-01
The research examined relational processing following stroke. Stroke patients (14 with frontal, 30 with non-frontal lesions) and 41 matched controls completed four relational processing tasks: sentence comprehension, Latin square matrix completion, modified Dimensional Change Card Sorting, and n-back. Each task included items at two or three…
Singh, Satya Pal; Singh, Apoorva; Hareet, Prabhav
2011-01-01
The progress of modern cosmology took off in 1917 when A. Einstein published his paper on general theory of relativity extending his work of special theory of relativity (1905). In 1922 Alexander Friedmann constructed a mathematical model for expanding Universe that had a big bang in remote past. The experimental evidences could come in 1929 by…
Ridgely, Charles T.
2010-01-01
Many textbooks dealing with general relativity do not demonstrate the derivation of forces in enough detail. The analyses presented herein demonstrate straightforward methods for computing forces by way of general relativity. Covariant divergence of the stress-energy-momentum tensor is used to derive a general expression of the force experienced…
Antecedents of Relational Capital
DEFF Research Database (Denmark)
Nowinska, Agnieszka
This paper merges economic geography and relational capital perspective in order to analyze the proximity-based antecedents of relational assets in brokerage. It investigates empirically the role and interplay of geographical and cognitive proximity between a broker and her buyers in a quantitative...... for buyers characteristics. Lastly, I make use the under-researched empirical field of brokers....
DEFF Research Database (Denmark)
Blaagaard, Bolette
of cosmopolitanism from universal reproductions of sameness into creative productions of singular self-other relations based on the practiced and productive journalism. This is substantiated through case study analyses. The aim is to challenge the modern, rational journalistic subject referring back to the unified...... of the self-other relation which is simultaneously personal and political. Secondly, the dissertation relates the phenomenological ‘race’ and gender debates to the societal and productive context of contemporary European and ‘western’ globalised and mediated culture and politics. Journalism is re...... accountability and relation from journalistic training and practices whereby a ‘white’ and homogeneous social imaginary is reproduced. I make a call for thinking about journalism as relation – in terms of technological mediations, but also in terms of subjectivities. In order to allow for this, a shift is needed...
Relative Lyapunov Center Bifurcations
DEFF Research Database (Denmark)
Wulff, Claudia; Schilder, Frank
2014-01-01
Relative equilibria (REs) and relative periodic orbits (RPOs) are ubiquitous in symmetric Hamiltonian systems and occur, for example, in celestial mechanics, molecular dynamics, and rigid body motion. REs are equilibria, and RPOs are periodic orbits of the symmetry reduced system. Relative Lyapunov...... center bifurcations are bifurcations of RPOs from REs corresponding to Lyapunov center bifurcations of the symmetry reduced dynamics. In this paper we first prove a relative Lyapunov center theorem by combining recent results on the persistence of RPOs in Hamiltonian systems with a symmetric Lyapunov...... center theorem of Montaldi, Roberts, and Stewart. We then develop numerical methods for the detection of relative Lyapunov center bifurcations along branches of RPOs and for their computation. We apply our methods to Lagrangian REs of the N-body problem....
Ether formulations of relativity
International Nuclear Information System (INIS)
Duffy, M.C.
1980-01-01
Contemporary ether theories are surveyed and criticised, especially those formally identical to orthodox Relativity. The historical development of Relativity, Special and General, in terms of an ether, is briefly indicated. Classical interpretations of Generalized Relativity using ether are compared to Euclidean formulations using a background space. The history of a sub-group of theories, formulating a 'new' Relativity involving modified transforms, is outlined. According to the theory with which they agree, recent supposed detections of drift are classified and criticised. Cosmological evidence suggesting an ether is mentioned. Only ether theories formally identical to Relativity have been published in depth. They stand criticised as being contrary to the positivist spirit. The history of mechanical analogues is traced, from Hartley's representing gravitating matter as spherical standing waves, to recent suggestions that vortex-sponge might model electromagnetic, quantum, uncertainty and faster-than-light phenomena. Contemporary theories are particular physical theories, themselves 'second interpretations' of a primary mathematical model. Mechanical analogues are auxiliary, not necessary, to other theory, disclosing relationships between classical and non-classical descriptions of assemblies charging state. The ether-relativity polemic, part of a broader dispute about relativity, is founded on mistaken conceptions of the roles of mathematical and physical models, mechanical analogues; and a distored view of history, which indicates that ether theories have become relativistic. (author)
Modernization of credit relations
Directory of Open Access Journals (Sweden)
S.V. Volosovich
2015-03-01
Full Text Available Nowadays it is essential to modernize credit relations in the conditions of global economy transformations. This is due to the influence of integration processes on credit relations and transformation of the risks inherent in the credit field. The purpose of this article is to develop measures that help to improve the efficiency of interaction of credit relations’ participants. Modernization of credit relations is based on the interaction of its main and indirect subjects who belong to the subsystems of loans granting, deposits attraction and provision of related services. Its goal is to pass from extensive to intensive model of interaction between the subjects of credit relations. Components of the credit relations modernization are the following: institutional modernization, which is based on the interaction of credit relations’ subjects, and ensures the development of competition in all credit market’s segments, the creation of its corresponding infrastructure, qualitative change in the approaches of regulation and supervision; technological modernization, which involves the formation of joint products on the credit market and the formation of an integrated informational and analytical system. In the result of the credit relations’ modernization it is expected to achieve synergies between the subjects of credit relations, that will lead to changes in the business architecture of the financial market.
International Nuclear Information System (INIS)
Magnon, A.
1998-01-01
A relational approach to be observable universe is proposed, which precludes the concept of absolute background. Space-time events emerge as dynamical entities which owe their existence to a memorization process, itself inter wind with the availability of cosmological horizons (screening from totality) sourcing long-range correlations. The resulting (and relational) mode of description sheds light on various paradoxes (EPR, Foucault pendolum, light beam effect, etc.), on the problem of instantaneous and global influences (quark deconfinement) as related to the interconnectedness of our cosmos. This scenario leads to comment on living systems vs. robots, and on non-recursive and global aspects of the mathematical intuition
Kilmister, Clive William
1970-01-01
Special Theory of Relativity provides a discussion of the special theory of relativity. Special relativity is not, like other scientific theories, a statement about the matter that forms the physical world, but has the form of a condition that the explicit physical theories must satisfy. It is thus a form of description, playing to some extent the role of the grammar of physics, prescribing which combinations of theoretical statements are admissible as descriptions of the physical world. Thus, to describe it, one needs also to describe those specific theories and to say how much they are limit
Hoffmann, William F
1964-01-01
Remarks on the observational basis of general relativity ; Riemannian geometry ; gravitation as geometry ; gravitational waves ; Mach's principle and experiments on mass anisotropy ; the many faces of Mach ; the significance for the solar system of time-varying gravitation ; relativity principles and the role of coordinates in physics ; the superdense star and the critical nucleon number ; gravitation and light ; possible effects on the solar system of φ waves if they exist ; the Lyttleton-Bondi universe and charge equality ; quantization of general relativity ; Mach's principle as boundary condition for Einstein's equations.
DEFF Research Database (Denmark)
Korneliussen, Thorfinn Sand; Moltke, Ida
2015-01-01
. Using both simulated and real data, we show that NgsRelate provides markedly better estimates for low-depth NGS data than two state-of-the-art genotype-based methods. AVAILABILITY: NgsRelate is implemented in C++ and is available under the GNU license at www.pop gen.dk/software. CONTACT: ida...... be called with high certainty. RESULTS: We present a software tool, NgsRelate, for estimating pairwise relatedness from NGS data. It provides maximum likelihood estimates that are based on genotype likelihoods instead of genotypes and thereby takes the inherent uncertainty of the genotypes into account...
International Nuclear Information System (INIS)
MacRoberts, D.T.
1980-01-01
A kinematic theory without precise definitions of the 'space' and 'time' used is an uninterpreted calculus. The definition of 'time' in special relativity is based on light propagation and the 'constant velocity of light' is a tautological consequence of the definition. When this definition is reified in a 'clock' the phenomenon of 'time dilation' occurs, in terms of the defined time, but is not reciprocal between moving systems; the postulate of relativity is not observed. The new definition of time is compatible with an ether theory without the relativity principle. The derivation of the Lorentz transformations, which requires both postulates, is purely formalistic and is not ontologically sound. (Auth.)
Public Relations vs. Propaganda
Directory of Open Access Journals (Sweden)
Alexandru BASTIAN
2006-10-01
Full Text Available The paper aims at presenting the characteristics, methods and aplications of two related activities – Public Relations and propaganda. Although different from the piont of wiev of purpose and results (the practice of Public Relations aims at establishing and maintaining mutual lines of communications, understanding, acceptance, and cooperation between an organization and its publics, through transparency and honesty, while propaganda insists on a message that is intended primarily to serve the interests of the messenger. in order to influence public opinion and to manipulate other people’s beliefs by any means necessary, the two activities also present quite a lot of similarities.
Givant, Steven
2017-01-01
This monograph details several different methods for constructing simple relation algebras, many of which are new with this book. By drawing these seemingly different methods together, all are shown to be aspects of one general approach, for which several applications are given. These tools for constructing and analyzing relation algebras are of particular interest to mathematicians working in logic, algebraic logic, or universal algebra, but will also appeal to philosophers and theoretical computer scientists working in fields that use mathematics. The book is written with a broad audience in mind and features a careful, pedagogical approach; an appendix contains the requisite background material in relation algebras. Over 400 exercises provide ample opportunities to engage with the material, making this a monograph equally appropriate for use in a special topics course or for independent study. Readers interested in pursuing an extended background study of relation algebras will find a comprehensive treatme...
Jackson, A. T.
1973-01-01
Reviews theoretical and experimental fundamentals of Einstein's theory of general relativity. Indicates that recent development of the theory of the continually expanding universe may lead to revision of the space-time continuum of the finite and unbounded universe. (CC)
General relativity and experiment
Damour, T.
1994-01-01
The confrontation between Einstein's theory of gravitation and experiment is summarized. Although all current experimental data are compatible with general relativity, the importance of pursuing the quest for possible deviations from Einstein's theory is emphasized.
Directory of Open Access Journals (Sweden)
Jéssica Natuline Ianof
Full Text Available ABSTRACT Traumatic brain injury (TBI is a major cause of lifelong disability and death worldwide. Sport-related traumatic brain injury is an important public health concern. The purpose of this review was to highlight the importance of sport-related concussions. Concussion refers to a transient alteration in consciousness induced by external biomechanical forces transmitted directly or indirectly to the brain. It is a common, although most likely underreported, condition. Contact sports such as American football, rugby, soccer, boxing, basketball and hockey are associated with a relatively high prevalence of concussion. Various factors may be associated with a greater risk of sport-related concussion, such as age, sex, sport played, level of sport played and equipment used. Physical complaints (headache, fatigue, dizziness, behavioral changes (depression, anxiety, irritability and cognitive impairment are very common after a concussion. The risk of premature return to activities includes the prolongation of post-concussive symptoms and increased risk of concussion recurrence.
Relativity of Visual Communication
Directory of Open Access Journals (Sweden)
Arto Mutanen
2016-03-01
Full Text Available Communication is sharing and conveying information. In visual communication especially visual messages have to be formulated and interpreted. The interpretation is relative to a method of information presentation method which is human construction. This holds also in the case of visual languages. The notions of syntax and semantics for visual languages are not so well founded as they are for natural languages. Visual languages are both syntactically and semantically dense. The density is connected to the compositionality of the (pictorial languages. In the paper Charles Sanders Peirce’s theory of signs will be used in characterizing visual languages. This allows us to relate visual languages to natural languages. The foundation of information presentation methods for visual languages is the logic of perception, but only if perception is understood as propositional perception. This allows us to understand better the relativity of information presentation methods, and hence to evaluate the cultural relativity of visual communication.
Full Text Available ... Your Wishes Visiting The ER Who Takes Care Of You In An Emergency? Checking Into ... Illnesses Dr. Glenn Mitchell , Emergency physician at Mercy Health System in Chesterfield, Missouri Heat-related illness can be ...
Full Text Available ... Health System in Chesterfield, Missouri Heat-related illness can be caused by overexposure to the sun or ... the elderly are most at risk, but anyone can be affected. Here you will find information about ...
Publicity and public relations
Fosha, Charles E.
1990-01-01
This paper addresses approaches to using publicity and public relations to meet the goals of the NASA Space Grant College. Methods universities and colleges can use to publicize space activities are presented.
Full Text Available ... ICE” in Your Cell Phone Prepare for Disasters Communication With Your Family And Your Doctor About Your ... Dr. Glenn Mitchell , Emergency physician at Mercy Health System in Chesterfield, Missouri Heat-related illness can be ...
Deruelle, Nathalie
2018-01-01
This comprehensive textbook on relativity integrates Newtonian physics, special relativity and general relativity into a single book that emphasizes the deep underlying principles common to them all, yet explains how they are applied in different ways in these three contexts. Newton's ideas about how to represent space and time, his laws of dynamics, and his theory of gravitation established the conceptual foundation from which modern physics developed. Book I in this volume offers undergraduates a modern view of Newtonian theory, emphasizing those aspects needed for understanding quantum and relativistic contemporary physics. In 1905, Albert Einstein proposed a novel representation of space and time, special relativity. Book II presents relativistic dynamics in inertial and accelerated frames, as well as a detailed overview of Maxwell's theory of electromagnetism. This provides undergraduate and graduate students with the background necessary for studying particle and accelerator physics, astrophysics and ...
K.P.C. Dokter (Kasper); S.-S.T.Q. Jongmans (Sung-Shik); F. Arbab (Farhad); S. Bliudze (Simon)
2015-01-01
textabstractCoordination languages simplify design and development of concurrent systems. Particularly, exogenous coordination languages, like BIP and Reo, enable system designers to express the interactions among components in a system explicitly. In this paper we establish a formal relation
K.P.C. Dokter (Kasper); S.-S.T.Q. Jongmans (Sung-Shik); F. Arbab (Farhad); S. Bliudze (Simon); S. Knight; I. Lanese; A. Lluch Lafuente; H.T. Vieira
2015-01-01
htmlabstractCoordination languages simplify design and development of concurrent systems. Particularly, exogenous coordination languages, like BIP and Reo, enable system designers to express the interactions among components in a system explicitly. In this paper we establish a formal relation
International Nuclear Information System (INIS)
Aldrovandi, R; Almeida, J P Beltran; Pereira, J G
2007-01-01
A special relativity based on the de Sitter group is introduced, which is a theory that might hold up in the presence of a non-vanishing cosmological constant. Like ordinary special relativity, it retains the quotient character of spacetime, and a notion of homogeneity. As a consequence, the underlying spacetime will be a de Sitter spacetime, whose associated kinematics will differ from that of ordinary special relativity. The corresponding modified notions of energy and momentum are obtained, and the exact relationship between them, which is invariant under a re-scaling of the involved quantities, explicitly exhibited. Since the de Sitter group can be considered a particular deformation of the Poincare group, this theory turns out to be a specific kind of deformed (or doubly) special relativity. Some experimental consequences, as well as the causal structure of spacetime-modified by the presence of the de Sitter horizon-are briefly discussed
International Nuclear Information System (INIS)
Antmann, K.; Aisner, J.
1986-01-01
This book contains 20 chapters. Some of the chapter titles are: The Radiology of Asbestosis and Related Neoplasms; Computed Tomography and Malignant Mesothelioma; Radiation Therapy for Pleural Mesothelioma; and Radiation Therapy of Peritoneal Mesothelioma
DEFF Research Database (Denmark)
Sproedt, Henrik; Buur, Jacob
2010-01-01
This paper describes a case of user-driven innovation. We draw on social capital theory and the concept of complex responsive processes to examine the role of relations for the exchange and generation of knowledge across different knowledge traditions. We argue that innovation as a social phenome...... phenomenon with a high degree of uncertainty and complexity requires more relating and less managing to use conflict as a resource by turning the friction between different knowledge traditions into creative friction....
International Nuclear Information System (INIS)
Schmutzer, E.
1979-01-01
Issued on the occasion of Albert Einstein's 100th birthday the book deals topically with the special and general relativity theory. The latest experiments to confirm the relativity theory are described and the historical development of the theory is presented in detail. Emphasis is given to the disclosure of deep insights into the nature of matter. Of interest to experts in physical and natural sciences and to mathematicians
Babu; Barr
2000-08-07
A generalization of the well-known Georgi-Jarlskog relation (m(&mgr;)/m(tau)) = 3(m(s)/m(b)) to neutrinos is found in the context of SO(10). This new relation is (m(nu(&mgr;))/m(nu(tau))) = 16(m(c)/m(t)), which is consistent with present data, assuming the Mikheyev-Smirnov-Wolfenstein solution to the solar neutrino problem.
International Nuclear Information System (INIS)
Babu, K. S.; Barr, S. M.
2000-01-01
A generalization of the well-known Georgi-Jarlskog relation (m μ /m τ ) =3(m s /m b ) to neutrinos is found in the context of SO(10) . This new relation is (m ν μ /m ν τ )=16(m c /m t ) , which is consistent with present data, assuming the Mikheyev-Smirnov-Wolfenstein solution to the solar neutrino problem. (c) 2000 The American Physical Society
Classifying Linear Canonical Relations
Lorand, Jonathan
2015-01-01
In this Master's thesis, we consider the problem of classifying, up to conjugation by linear symplectomorphisms, linear canonical relations (lagrangian correspondences) from a finite-dimensional symplectic vector space to itself. We give an elementary introduction to the theory of linear canonical relations and present partial results toward the classification problem. This exposition should be accessible to undergraduate students with a basic familiarity with linear algebra.
The metamorphoses of relativity
Staley, Richard
This talk will explore the ways that problems shifted and disciplinary boundaries changed around physicists' engagement with relational physics and relativistic thought, first in research dealing with physiology, psychology and geometry in the late nineteenth century and then (a better-known story) moving between physics, mathematics and geometry in the twentieth century. I hope to develop a richer approach for understanding the disciplinary and political significance of relativity, especially by considering in one framework the work of Engels, Mach, Einstein and Planck.
General Relativity and Gravitation
Ehlers, J.; Murdin, P.
2000-11-01
The General Theory of Relativity (GR), created by Albert Einstein between 1907 and 1915, is a theory both of gravitation and of spacetime structure. It is based on the assumption that matter, via its energy-momentum, interacts with the metric of spacetime, which is considered (in contrast to Newtonian physics and SPECIAL RELATIVITY) as a dynamical field having degrees of freedom of its own (GRAVI...
INTERPERSONAL RELATIONS IN SCHOOL
Directory of Open Access Journals (Sweden)
Siniša Opić
2016-12-01
Full Text Available As part of the scientific project titled “The Curriculum of Social Competences and Relations in School”, the aim of this paper is to examine the quality of interpersonal relations between teachers and pupils. On a sample of 432 teachers from 20 towns, 35 primary schools in the Republic of Croatia, and 432 pupils, it was confirmed that there is a difference in the appraisal of the quality of their interpersonal relations. Although the overall quality of interpersonal relations between pupils and teachers is at a moderately satisfactory level, pupils still appraise the quality of interpersonal relations lower than their teachers. In view of latent dimensionality, a factor questionnaire structure was used (14 variables; ordinal type and two main components (subscales determined: didactic support and interaction, and rough verbal and physical treatment. As part of the differential draft of our research, no gender differences were established (between female and male teachers in the appraisal of the quality of interpersonal relations with pupils (on two subscales. The correlation analysis confirmed a low negative statistically significant correlation between the years of service and the subscale rough verbal and physical treatment (Rho=-0.101. In view of the subscale of rough verbal and physical treatment between pupils and teachers, such results on a negative correlation imply that older teachers, as opposed to their younger colleagues, use more corporal punishment in schools, treat pupils rudely, use nasty and impolite words, and call pupils insulting names.
International Nuclear Information System (INIS)
Deruelle, N.; Uzan, J.P.
2014-01-01
This book is a quite complete route towards general relativity via special relativity with a start point at Newton's mechanics. The mathematical formulation is based on tensors. All the relativistic aspects of only classical physics - it means no quantum mechanics - are exposed. This book is divided into 3 books and each book represents a consistent knowledge of physics at a certain time in the past: in Newton's time, in the second half of the 19. century and today. The advantage of this presentation is to make the reader feels the changes over time in the concepts of time, space, gravity, cosmology. Each book is divided into 3, 4 and 5 parts which are sub-divided into numerous chapters. Book 1: Space, time and gravity in Newton's theory, with part 1: kinematics, part 2: dynamics and part 3: gravity. Book 2: Special relativity and Maxwell's theory, with part 1: kinematics, part 2: dynamics, part 3: electromagnetism and part 4: electrodynamics. And Book 3: General relativity and gravity, with part 1: curved space-time and gravity, part 2: Schwarzschild solution and black holes, part 3: general relativity and experiments, part 4: Friedman-Lemaitre solutions and cosmology, and part 5: elements or Riemann geometry. The 3. book dedicated to general relativity, tackles topics like the relationships between space-time curvature and gravity, Schwarzschild solutions and black holes, gravitational waves, Friedmann-Lemaitre solutions and cosmology, and Riemann geometry. (A.C.)
STRATEGI KOMUNIKASI PUBLIC RELATIONS
Directory of Open Access Journals (Sweden)
Artis Artis
2011-11-01
Full Text Available Living man in interrelates society. Relationship among human being done by gets communication so man one by another one mutually understand and influence regard for the benefit, it that always been practiced by Public Relations( liaison in a governance and also firm institute to reach to the effect which ices. The institute of Public Relations declares for,”Public Relations is overall effort which be passed off by design and berkesenambungan in order to creates and pet keenness and mutual understanding among an organization with whole its member “. In this case, Public Relations in give distribution on manajement's strategy there is two: First, Doing task as part of Public Relations's strategy and involvement in comprehensive process and gives benefit for management an organization. Both of, Public Relations gets role in management strategy in bring off activity to reach to the effect good one gets internal character and also external one correspond to that desirable by good institute on level governance and firm.
De Sitter projective relativity
Licata, Ignazio; Benedetto, Elmo
2017-01-01
This book presents the Projective approach to de Sitter Relativity. It traces the development of renewed interest in models of the universe at constant positive curvature such as "vacuum" geometry. The De Sitter Theory of Relativity, formulated in 1917 with Willem De Sitter's solution of the Einstein equations, was used in different fields during the 1950s and 1960s, in the work of H. Bacry, J.M. LevyLeblond and F.Gursey, to name some important contributors. From the 1960s to 1980s, L. Fantappié and G. Arcidiacono provided an elegant group approach to the De Sitter universe putting the basis for special and general projective relativity. Today such suggestions flow into a unitary scenario, and this way the De Sitter Relativity is no more a "missing opportunity" (F. Dyson, 1972), but has a central role in theoretical physics. In this volume a systematic presentation is given of the De Sitter Projective relativity, with the recent developments in projective general relativity and quantum cosmology.
Algorithmic Relative Complexity
Directory of Open Access Journals (Sweden)
Daniele Cerra
2011-04-01
Full Text Available Information content and compression are tightly related concepts that can be addressed through both classical and algorithmic information theories, on the basis of Shannon entropy and Kolmogorov complexity, respectively. The definition of several entities in Kolmogorov’s framework relies upon ideas from classical information theory, and these two approaches share many common traits. In this work, we expand the relations between these two frameworks by introducing algorithmic cross-complexity and relative complexity, counterparts of the cross-entropy and relative entropy (or Kullback-Leibler divergence found in Shannon’s framework. We define the cross-complexity of an object x with respect to another object y as the amount of computational resources needed to specify x in terms of y, and the complexity of x related to y as the compression power which is lost when adopting such a description for x, compared to the shortest representation of x. Properties of analogous quantities in classical information theory hold for these new concepts. As these notions are incomputable, a suitable approximation based upon data compression is derived to enable the application to real data, yielding a divergence measure applicable to any pair of strings. Example applications are outlined, involving authorship attribution and satellite image classification, as well as a comparison to similar established techniques.
Forshaw, Jeffrey
2009-01-01
A new title in the Manchester Physics Series, this introductory text emphasises physical principles behind classical mechanics and relativity. It assumes little in the way of prior knowledge, introducing relevant mathematics and carefully developing it within a physics context. Designed to provide a logical development of the subject, the book is divided into four sections, introductory material on dynamics, and special relativity, which is then followed by more advanced coverage of dynamics and special relativity. Each chapter includes problems ranging in difficulty from simple to challenging with?solutions for solving problems. Includes?solutions for solving problemsNumerous worked examples included throughout the bookMathematics is carefully explained and developed within a physics environmentSensitive to topics that can appear daunting or confusing
International Nuclear Information System (INIS)
Hayashi, K.; Shirafuji, T.
1979-01-01
A gravitational theory is formulated on the Weitzenboeck space-time, characterized by the vanishing curvature tensor (absolute parallelism) and by the torsion tensor formed of four parallel vector fields. This theory is called new general relativity, since Einstein in 1928 first gave its original form. New general relativity has three parameters c 1 , c 2 , and lambda, besides the Einstein constant kappa. In this paper we choose c 1 = 0 = c 2 , leaving open lambda. We prove, among other things, that (i) a static, spherically symmetric gravitational field is given by the Schwarzschild metric, that (ii) in the weak-field approximation an antisymmetric field of zero mass and zero spin exists, besides gravitons, and that (iii) new general relativity agrees with all the experiments so far carried out
International Nuclear Information System (INIS)
Penrose, R.
1979-01-01
Much theoretical work in General Relativity has been concerned with finding explicit solutions of Einstein field equations. Exact solutions must involve simplifying procedures which in the case of strong gravitational fields may not be valid. Computers can help but complementary to these are the global qualitative mathematics that have been introduced into relativity over the past years. These have shown that Einstein's equations together with suitable inequalities on the energy-momentum tensor can lead inevitably to space-time singularities arising, provided that some qualitative geometric criterion is satisfied. It seems that in suitable situations of gravitational collapse this criterion will be satisfied. Similarly in a cosmological setting the criterion can be applied in the reverse direction in time. There is, however, the unsolved problem in general relativity of cosmic censorship and this is discussed as a consequence of Einstein's equations. (UK)
International Nuclear Information System (INIS)
Clarke, C.
1979-01-01
The plan of the book is as follows: Chapter 1 develops special relativity in a setting and notation that can immediately be transferred to general relativity. Most of the fundamental geometrical ideas are established here. Chapter 2 gives a more conventional account of some selected applications of special relativity. Chapter 3 is the heart of the book. A geometrical model of space-time is progressively built up, motivated by physical arguments stemming from the equivalence principle, leading to Einstein's field equations. Chapter 4 deals very quickly with the simplest form of weak-field theory with application to gravitational radiation. Chapter 5 concludes the book with a fairly detailed analysis of the Schwarzschild solution, plane fronted gravitational waves, and the Robertson-Walker cosmological solutions. Exercises at the end of each chapter extend the general theory into particular applications, giving a broader picture of the scope of the subject. (author)
Tensors, relativity, and cosmology
Dalarsson, Mirjana
2015-01-01
Tensors, Relativity, and Cosmology, Second Edition, combines relativity, astrophysics, and cosmology in a single volume, providing a simplified introduction to each subject that is followed by detailed mathematical derivations. The book includes a section on general relativity that gives the case for a curved space-time, presents the mathematical background (tensor calculus, Riemannian geometry), discusses the Einstein equation and its solutions (including black holes and Penrose processes), and considers the energy-momentum tensor for various solutions. In addition, a section on relativistic astrophysics discusses stellar contraction and collapse, neutron stars and their equations of state, black holes, and accretion onto collapsed objects, with a final section on cosmology discussing cosmological models, observational tests, and scenarios for the early universe. This fully revised and updated second edition includes new material on relativistic effects, such as the behavior of clocks and measuring rods in m...
Introduction to special relativity
International Nuclear Information System (INIS)
Rindler, W.
1982-01-01
This is intended as a text for an introductory course on special relativity; it assumes no prior knowledge of relativity. It is intended for the upper undergraduate level and upwards. The first three chapters take a three-dimensional viewpoint for a simple introduction to topics such as the relativity of simultaneity, length contraction, time dilation, the twin paradox and the appearance of moving objects. For the remaining chapters the strongest possible use is made of four-dimensional techniques. Chapter four deals with space-time, chapters five and six with mechanics and electromagnetism. In these a purely synthetic four-tensor approach is adopted. Pure tensor theory is covered in an appendix. The last chapter is on the mechanics of continua. (U.K.)
Essential dynamics and relativity
O'Donnell, Peter J
2014-01-01
Essential Dynamics & Relativity provides students with an introduction to the core aspects of dynamics and special relativity. The author reiterates important ideas and terms throughout and covers concepts that are often missing from other textbooks at this level. He also places each topic within the wider constructs of the theory, without jumping from topic to topic to illustrate a point.The first section of the book focuses on dynamics, discussing the basic aspects of single particle motion and analyzing the motion of multi-particle systems. The book also explains the dynamical behavior of b
Hoffmann, Banesh
1998-01-01
In this fascinating, accessible introduction to one of the most revolutionary developments in modern physics, Einstein scholar Banesh Hoffmann recounts the successive insights that led to both the special and general theories of relativity.Using simple examples from everyday life, the author presents entertaining, nontechnical demonstrations of what relativity actually means and how it has revolutionized our ideas of time and space. Starting with the geometrical and cosmological ideas of the ancient Greeks, the author traces the succession of ideas and advances that paved the way for modern p
DEFF Research Database (Denmark)
Schürmann, Carsten; Sarnat, Jeffrey
2008-01-01
Tait's method (a.k.a. proof by logical relations) is a powerful proof technique frequently used for showing foundational properties of languages based on typed lambda-calculi. Historically, these proofs have been extremely difficult to formalize in proof assistants with weak meta-logics......, such as Twelf, and yet they are often straightforward in proof assistants with stronger meta-logics. In this paper, we propose structural logical relations as a technique for conducting these proofs in systems with limited meta-logical strength by explicitly representing and reasoning about an auxiliary logic...
Turbine related fish mortality
International Nuclear Information System (INIS)
Eicher, G.J.
1993-01-01
A literature review was conducted to assess the factors affecting turbine-related fish mortality. The mechanics of fish passage through a turbine is outlined, and various turbine related stresses are described, including pressure and shear effects, hydraulic head, turbine efficiency, and tailwater level. The methodologies used in determining the effects of fish passage are evaluated. The necessity of adequate controls in each test is noted. It is concluded that mortality is the result of several factors such as hardiness of study fish, fish size, concentrations of dissolved gases, and amounts of cavitation. Comparisons between Francis and Kaplan turbines indicate little difference in percent mortality. 27 refs., 5 figs
Directory of Open Access Journals (Sweden)
Stergioulas Nikolaos
2003-01-01
Full Text Available Rotating relativistic stars have been studied extensively in recent years, both theoretically and observationally, because of the information they might yield about the equation of state of matter at extremely high densities and because they are considered to be promising sources of gravitational waves. The latest theoretical understanding of rotating stars in relativity is reviewed in this updated article. The sections on the equilibrium properties and on the nonaxisymmetric instabilities in f-modes and r-modes have been updated and several new sections have been added on analytic solutions for the exterior spacetime, rotating stars in LMXBs, rotating strange stars, and on rotating stars in numerical relativity.
Bourdieu in International Relations
DEFF Research Database (Denmark)
The last few years have seen a genuine wave of publications promoting sociology in international relations. Scholars have suggested that Bourdieu’s vocabulary can be applied to study security, diplomacy, migration and global environmental politics. Yet we still lack a systematic and accessible....... The chapters demonstrate how these concepts can be reinterpreted and used in new ways when exposed to Bourdieusian logic. Challenging key pillars of IR scholarship, Bourdieu in International Relations will be of interest to critical theorists, and scholars of IR theory....
Nuclear energy related research
International Nuclear Information System (INIS)
Toerroenen, K.; Kilpi, K.
1985-01-01
This research programme plan for 1985 covers the nuclear energy related research planned to be carried out at the Technical Research Centre of Finland (VTT) and funded by the Ministry of Trade and Industry in Finland, the Nordic Council of Ministers and VTT
International Nuclear Information System (INIS)
Penrose, Roger
2007-01-01
Goedel's acquaintance with Einstein led him to discover, by use of novel techniques, an exotic cosmological model which flouted many preconceived notions, such as the role of Mach's principle in general relativity and the nature of time. Goedel also invoked it in speculations concerning the question of minds
MARC and Relational Databases.
Llorens, Jose; Trenor, Asuncion
1993-01-01
Discusses the use of MARC format in relational databases and addresses problems of incompatibilities. A solution is presented that is in accordance with Open Systems Interconnection (OSI) standards and is based on experiences at the library of the Universidad Politecnica de Valencia (Spain). (four references) (EA)
International Nuclear Information System (INIS)
Banai, M.
1983-11-01
A quantum relativity theory formulated in terms of Davis' quantum relativity principle is outlined. The first task in this theory as in classical relativity theory is to model space-time, the arena of natural processes. It is argued that the quantum space-time models of Banai introduced in an earlier paper is formulated in terms of Davis' quantum relativity. Then it is shown that the recently proposed classical relativistic quantum theory of Prugovecki and his corresponding classical relativistic quantum model of space-time open the way to introduce in a consistent way the quantum space-time model (the 'canonically quantized Minkowski space') proposed by Banai earlier. The main new aspect of the quantum mechanics of the quantum relativistic particles is, in this model of space-time, that it provides a true mass eigenvalue problem and, that the excited mass states of such particles can be interpreted as classifically relativistic (massive) quantum particles ('elementary particles'). The question of field theory over quantum relativistic models of space-time is also discussed. Finally, it is suggested that 'quarks' should be considered as quantum relativistic particles. (author)
Buck, Tina; Sales, Amos
This paper provides an overview of addiction related to substance abuse. It provides basic information, prevalence, diagnostic criteria, assessment tools, and treatment issues for eating disorders, compulsive gambling, sex addictions, and work addictions. Eating disorders such as anorexia nervosa and bulimia nervosa, especially affect adolescents.…
International Nuclear Information System (INIS)
Rosen, N.
1979-01-01
A modification of general relativity is proposed involving a second metric tensor describing a space-time of constant curvature and associated with the fundamental rest-frame of the universe. The theory generally agrees with the Einstein theory, but gives cosmological models without singularities which can account for present observation, including helium abundance
Van der Vegt, Wim
2010-01-01
Related Drupal Nodes Block This module exposes a block that uses Latent Semantic Analysis (Lsa) internally to suggest three nodes that are relevant to the node a user is viewing. This module performs three tasks. 1) It periodically indexes a Drupal site and generates a Lsa Term Document Matrix.
Nuclear energy related research
International Nuclear Information System (INIS)
Salminen, Pertti
1989-03-01
This annual Research Programme Plan covers the publicly funded nuclear energy related research planned to be carried out at the Technical Research Centre of Finland (VTT) in 1989. The research will be financed by the Ministry of Trade and Industry, the Finnish Centre for Radiation and Nuclear Safety, the Nordic Council of Ministers and VTT itself
Relational Aggression among Students
Young, Ellie L.; Nelson, David A.; Hottle, America B.; Warburton, Brittney; Young, Bryan K.
2011-01-01
"Relational aggression" refers to harm within relationships caused by covert bullying or manipulative behavior. Examples include isolating a youth from his or her group of friends (social exclusion), threatening to stop talking to a friend (the silent treatment), or spreading gossip and rumors by email. This type of bullying tends to be…
Czech Academy of Sciences Publication Activity Database
Svoboda, David
2016-01-01
Roč. 6, č. 1 (2016), s. 147-172 ISSN 1804-5588 Institutional support: RVO:67985955 Keywords : relation and its foundation * Aquinas * order Subject RIV: AA - Philosophy ; Religion http://www.cupress.cuni.cz/ink2_stat/index.jsp?include=AUC_clanek&id=2868&id=5343&casopis=921&zalozka=0&predkl=0
Nuclear energy related research
International Nuclear Information System (INIS)
Salminen, P.; Mattila, L.
1990-08-01
The annual Research Programme Plan describes the publicly funded nuclear energy related research to be carried out at the Technical Research Centre of Finland (VTT) in 1990. The research is financed primarily by the Ministry of Trade and Industry (KTM), the Finnish Centre for Radiation and Nuclear Safety (STUK) and VTT itself. Utilities and industry also contribute to some projects
International Nuclear Information System (INIS)
Maia, M.D.
2006-01-01
It is shown that the information loss/recovery theorem based on the ADS/CFT correspondence is not consistent with the stability of the Schwarzschild or Reissner-Nordstrom black holes. Nonetheless, the conformal invariance of Yang-Mills theory points to new relativity principle compatible with quantum unitarity near those black holes
R. Veenhoven (Ruut)
1991-01-01
textabstractABSTRACT The theory that happiness is relative is based on three postulates: (1) happiness results from comparison. (2) standards of comparison adjust, (3) standards of comparison are arbitrary constructs. On the basis of these postulates the theory predicts: (a) happiness does not
Nuclear energy related research
International Nuclear Information System (INIS)
Mattila, L.; Vanttola, T.
1991-10-01
The annual Research Programme Plan describes the publicly funded nuclear energy related research to be carried out mainly at the Technical Research Centre of Finland (VTT) in 1991. The research is financed primarily by the Ministry of Trade and Industry (KTM), the Finnish Centre for Radiation and Nuclear Safety (STUK) and VTT itself. Other research institutes, utilities and industry also contribute to many projects
International Nuclear Information System (INIS)
Okun, L.B.
1991-01-01
This book presents papers on elementary particle physics, relations between various particles, and the connections between particle physics with other branches of physics. The papers include: Contemporary status and prospects of high-energy physics; Particle physics prospects; and High energy physics
DEFF Research Database (Denmark)
Skou, Niels Peter; Mikkelsen, Mette
2014-01-01
This paper examines the role of design methods in a social innovation project on a Danish Institution for severely physically and mentally handicapped people. The project was focused on ‘designing’ new or better relations between the residents at the institution and the civil society. During the ...
Employment Relations in Denmark
DEFF Research Database (Denmark)
Madsen, Jørgen Steen; Due, Jesper Jørgen; Andersen, Søren Kaj
2011-01-01
Jørgen Steen Madsen, Jesper Due og Søren Kaj Andersen har skrevet et kapitel om udviklingen i dansk arbejdsmarkedsregulering til bogen International and Comparative Employment Relations, redigeret af Greg Bamber, Russell Lansbury og Nick Wailes. Bogen indeholder bidrag, der præsenterer og...
International Nuclear Information System (INIS)
Bolter, H.
1982-01-01
The contributions made by BNFL to community relations are described in an illustrated booklet under the headings: introduction (general policy); donations and sponsorships; BNFL talks service; brochures and public information; visits; local liaison committees; industrial training; sponsored students; apprentices. (U.K.)
Nuclear energy related research
International Nuclear Information System (INIS)
Rintamaa, R.
1992-05-01
The annual Research Programme Plan describes publicly funded nuclear energy related research to be carried out mainly at the Technical Research Centre of Finland (VTT) in 1992. The research is financed primarily by the Ministry of Trade and Industry (KTM), the Finnish Centre for Radiation and Nuclear Safety (STUK) and VTT itself. Other research institutes, utilities and industry also contribute to many projects
Relational Demonic Fuzzy Refinement
Directory of Open Access Journals (Sweden)
Fairouz Tchier
2014-01-01
Full Text Available We use relational algebra to define a refinement fuzzy order called demonic fuzzy refinement and also the associated fuzzy operators which are fuzzy demonic join (⊔fuz, fuzzy demonic meet (⊓fuz, and fuzzy demonic composition (□fuz. Our definitions and properties are illustrated by some examples using mathematica software (fuzzy logic.
Indian Academy of Sciences (India)
D. Bhattacharyya
2018-02-09
Feb 9, 2018 ... SMBH than that of the nearby stars. The relation of the. SMBHs to their host galaxies can be seen by the strong correlation between the mass of SMBH and velocity dispersion σ of the stars in the galaxy. This is some- what surprising because the stars are too far from the. SMBH for the velocity dispersion to ...
Decreasing relative risk premium
DEFF Research Database (Denmark)
Hansen, Frank
2007-01-01
such that the corresponding relative risk premium is a decreasing function of present wealth, and we determine the set of associated utility functions. We find a new characterization of risk vulnerability and determine a large set of utility functions, closed under summation and composition, which are both risk vulnerable...
Brady, Don; Brady, Flo
2011-01-01
Sport-related concussions (SRC) are not limited to specific age ranges, professional athletes, or gender. The primary focus of much of SRC research pertains to the assessment, management, and return to play (RTP) of the concussed athlete. This article highlights some major issues of SRC along with some controversies that presently exist within the…
Baranov G. V.
2016-01-01
the article reveals the importance of communication with the public in the implementation of human rights and the ideals of mankind; characterized by the specificity of public relations in the information culture of belief; PR functions are explained on the criterion of optimization of activity of social interactions on the basis of cultural ideals.
Nuclear energy related research
International Nuclear Information System (INIS)
Salminen, Pertti
1987-02-01
This annual Research Programme Plan covers the nuclear related research planned to be carried out at the Technical Research Centre of Finland (VTT) in 1987 and funded by the Ministry of Trade and Industry in Finland, the Nordic Council of Ministers and VTT itself
Houtman, I.L.D.
2005-01-01
Changes in the content and organisation of work in recent decades have resulted in an intensification of work, which is commonly regarded as a cause of stress. This report presents trends in the risks and consequences of work-related stress, and identifies how these can be prevented. The focus
Nuclear energy related research
International Nuclear Information System (INIS)
Salminen, P.
1988-02-01
This annual Research Programme Plan covers the publicly funded nuclear energy related research planned to be carried out at the Technical Research Centre of Finland (VTT) in 1988. The research will be financed by the Ministry of Trade and Industry, the Finnish Centre for Radiation and Nuclear Safety, the Nordic Council of Ministers and VTT itself
Om evalueringsforskningens relative autonomi
DEFF Research Database (Denmark)
Nørholm, Morten
2008-01-01
Det empiriske udgangspunkt for artiklen "Om evalueringsforskningens relative autonomi - dansk normal evalueringsforskning som et ikke-autonomt (sub)felt i magtens felt" er en række tekster af fire dominerende danske evalueringsforskere. Det teoretiske udgangspunkt er især Pierre Bourdieus teori om...
Correspondences. Equivalence relations
International Nuclear Information System (INIS)
Bouligand, G.M.
1978-03-01
We comment on sections paragraph 3 'Correspondences' and paragraph 6 'Equivalence Relations' in chapter II of 'Elements de mathematique' by N. Bourbaki in order to simplify their comprehension. Paragraph 3 exposes the ideas of a graph, correspondence and map or of function, and their composition laws. We draw attention to the following points: 1) Adopting the convention of writting from left to right, the composition law for two correspondences (A,F,B), (U,G,V) of graphs F, G is written in full generality (A,F,B)o(U,G,V) = (A,FoG,V). It is not therefore assumed that the co-domain B of the first correspondence is identical to the domain U of the second (EII.13 D.7), (1970). 2) The axiom of choice consists of creating the Hilbert terms from the only relations admitting a graph. 3) The statement of the existence theorem of a function h such that f = goh, where f and g are two given maps having the same domain (of definition), is completed if h is more precisely an injection. Paragraph 6 considers the generalisation of equality: First, by 'the equivalence relation associated with a map f of a set E identical to (x is a member of the set E and y is a member of the set E and x:f = y:f). Consequently, every relation R(x,y) which is equivalent to this is an equivalence relation in E (symmetrical, transitive, reflexive); then R admits a graph included in E x E, etc. Secondly, by means of the Hilbert term of a relation R submitted to the equivalence. In this last case, if R(x,y) is separately collectivizing in x and y, theta(x) is not the class of objects equivalent to x for R (EII.47.9), (1970). The interest of bringing together these two subjects, apart from this logical order, resides also in the fact that the theorem mentioned in 3) can be expressed by means of the equivalence relations associated with the functions f and g. The solutions of the examples proposed reveal their simplicity [fr
International Nuclear Information System (INIS)
Assis, A.K.T.
2011-01-01
Full text: Isaac Newton (1642-1727) defended in his book Mathematical Principles of Natural Philosophy, also know as Principia, published in 1687, the utilization of absolute time in physics. According to him 'absolute, true, and mathematical time, of itself, and from its own nature, flows equably without relation to anything external'. Leibniz (1646-1716), on the other hand, was against this concept and proposed relative time to replace it: 'As for my opinion, I have said more than once, that I hold space to be something merely relative, as time is; that I hold it to be an order of coexistence, as time is an order of successions'. Leibniz ideas were accepted and developed by Ernst Mach (1838-1916) in his book The Science of Mechanics, published in 1883. In this work we consider the implementation of relational time, as proposed by Leibniz and Mach, and the consequences this implementation will mean for physics as a whole. We consider some specific examples related to mechanics (Newton's bucket experiment, the flattening of the Earth, Foucault's pendulum experiment) and to electromagnetism (Ampere's force between current carrying wires, an electric charge describing a Larmor radius due to a nearby large magnet, two charges orbiting around one another). We generalize these ideas considering the principle of physical proportions (PPP), according to which no absolute magnitudes should appear in the laws of physics. We present some laws satisfying this principle and others which do not comply with it. The laws which do not satisfy the PPP should be based upon incomplete theories. We present the consequences of complete theories complying with this fundamental principle of nature. (author)
Energy Technology Data Exchange (ETDEWEB)
Assis, A.K.T. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)
2011-07-01
Full text: Isaac Newton (1642-1727) defended in his book Mathematical Principles of Natural Philosophy, also know as Principia, published in 1687, the utilization of absolute time in physics. According to him 'absolute, true, and mathematical time, of itself, and from its own nature, flows equably without relation to anything external'. Leibniz (1646-1716), on the other hand, was against this concept and proposed relative time to replace it: 'As for my opinion, I have said more than once, that I hold space to be something merely relative, as time is; that I hold it to be an order of coexistence, as time is an order of successions'. Leibniz ideas were accepted and developed by Ernst Mach (1838-1916) in his book The Science of Mechanics, published in 1883. In this work we consider the implementation of relational time, as proposed by Leibniz and Mach, and the consequences this implementation will mean for physics as a whole. We consider some specific examples related to mechanics (Newton's bucket experiment, the flattening of the Earth, Foucault's pendulum experiment) and to electromagnetism (Ampere's force between current carrying wires, an electric charge describing a Larmor radius due to a nearby large magnet, two charges orbiting around one another). We generalize these ideas considering the principle of physical proportions (PPP), according to which no absolute magnitudes should appear in the laws of physics. We present some laws satisfying this principle and others which do not comply with it. The laws which do not satisfy the PPP should be based upon incomplete theories. We present the consequences of complete theories complying with this fundamental principle of nature. (author)
Fluctuation Relations for Currents
Sinitsyn, Nikolai; Akimov, Alexei; Chernyak, Vladimir; Chertkov, Michael
2011-03-01
We consider a non-equilibrium statistical system on a graph or a network. Identical particles are injected, interact with each other, traverse, and leave the graph in a stochastic manner described in terms of Poisson rates, possibly strongly dependent on time and instantaneous occupation numbers at the nodes of the graph. We show that the system demonstrates a profound statistical symmetry, leading to new Fluctuation Relations that originate from the supersymmetry and the principle of the geometric universality of currents rather than from the relations between probabilities of forward and reverse trajectories. NSF/ECCS-0925618, NSF/CHE-0808910 and DOE at LANL under Contract No. DE-AC52-06NA25396.
Surviving relatives after suicide
DEFF Research Database (Denmark)
Nørrelykke, Helle; Cohrt, Pernille
and that suicide has become a subject of research, prevention and treatment. Auxiliary Strategies In the 1990s there have been established the Centre for Suicide Research and the Centre for Prevention of Suicide in Denmark and there has been drafted a national policy document which focuses on the need......We would like to focus on the surviving relatives after suicides, because it is generally accepted that it is especially difficult to recover after the loss from suicide and because we know as a fact that one suicide affects five persons on average. Every year approximately 700 people commit...... suicide in Denmark. This means that at least 400 people undergo the trauma it is when one of their near relatives commits suicide. We also know that the loss from suicide involves a lot of conflicting feelings - like anger, shame, guilt and loss and that the lack of therapy/treatment of these difficult...
Cosgrove, Joseph K
2018-01-01
In 1908, three years after Einstein first published his special theory of relativity, the mathematician Hermann Minkowski introduced his four-dimensional “spacetime” interpretation of the theory. Einstein initially dismissed Minkowski’s theory, remarking that “since the mathematicians have invaded the theory of relativity I do not understand it myself anymore.” Yet Minkowski’s theory soon found wide acceptance among physicists, including eventually Einstein himself, whose conversion to Minkowski’s way of thinking was engendered by the realization that he could profitably employ it for the formulation of his new theory of gravity. The validity of Minkowski’s mathematical “merging” of space and time has rarely been questioned by either physicists or philosophers since Einstein incorporated it into his theory of gravity. Physicists often employ Minkowski spacetime with little regard to the whether it provides a true account of the physical world as opposed to a useful mathematical tool in th...
THE RELATION APICULTURE - TOURISM
Directory of Open Access Journals (Sweden)
Goryana Yonkova
2016-06-01
Full Text Available The paper presents analyses of the current condition, trends and opportunities for the apiculture development and its relation to tourism in Bulgaria. Beekeeping is considered as a branch of agriculture since its formation after the liberation to the present day and in its dynamics of development for the last 5 years. Resource base including traditions, state, production and marketing of honey is presented. Data from the National Statistics Institute, Ministry of Agriculture, Food beekeepers' associations, processors and traders of honey and bee products, the Ministry of Tourism and tourism industry organizations is analyzed and discussed. Beekeeping is represented in the relation as a resource for development of apitourism, as untraditional attractive specialized type of tourism, which can support farmers through non-agricultural practices. The paper aimed at assisting companies and individuals in the field of agribusiness and apitourism for the realization of bee products and services.
International Nuclear Information System (INIS)
Santilli, R.M.
1991-09-01
In this note we further develop the proposal made in preceding works of constructing the infinite family of Lie-isotopic liftings of Galilei's relativity for closed-isolated systems of particles possessing local, potential and selfadjoint, as well as nonlocal, nonhamiltonian and non selfadjoint internal forces. In particular, we show that the nonlinear and nonlocal generalization of the Galilei transformations introduced in a preceding note do indeed represent motion of extended particles within resistive media, but in such a way to coincide with the conventional transformations at the abstract, realization-free level. This allows the preservation of the basic, physical and mathematical axioms of Galilei's relativity under our liftings, and their realization in the most general possible nonlinear, nonlocal and nonhamiltonian way. (author). 18 refs, 1 fig
Cohen, Andrew G; Glashow, Sheldon L
2006-07-14
By very special relativity (VSR) we mean descriptions of nature whose space-time symmetries are certain proper subgroups of the Poincaré group. These subgroups contain space-time translations together with at least a two-parameter subgroup of the Lorentz group isomorphic to that generated by K(x) + J(y) and K(y)- J(x). We find that VSR implies special relativity (SR) in the context of local quantum field theory or of conservation. Absent both of these added hypotheses, VSR provides a simulacrum of SR for which most of the consequences of Lorentz invariance remain wholly or essentially intact, and for which many sensitive searches for departures from Lorentz invariance must fail. Several feasible experiments are discussed for which Lorentz-violating effects in VSR may be detectable.
Numerical relativity beyond astrophysics
Garfinkle, David
2017-01-01
Though the main applications of computer simulations in relativity are to astrophysical systems such as black holes and neutron stars, nonetheless there are important applications of numerical methods to the investigation of general relativity as a fundamental theory of the nature of space and time. This paper gives an overview of some of these applications. In particular we cover (i) investigations of the properties of spacetime singularities such as those that occur in the interior of black holes and in big bang cosmology. (ii) investigations of critical behavior at the threshold of black hole formation in gravitational collapse. (iii) investigations inspired by string theory, in particular analogs of black holes in more than 4 spacetime dimensions and gravitational collapse in spacetimes with a negative cosmological constant.
DEFF Research Database (Denmark)
Løkken, Nicoline; Born, Alfred Peter; Duno, Morten
2015-01-01
INTRODUCTION: Muscular dystrophy caused by LAMA2-gene mutations is an autosomal recessive disease typically presenting as a severe, early-onset congenital muscular dystrophy (CMD). However, milder cases with a limb-girdle type muscular dystrophy (LGMD) have been described. METHODS: In this study......, we assessed the frequency and phenotypic spectrum of LAMA2-related muscular dystrophy in CMD (n = 18) and LGMD2 (n = 128) cohorts identified in the last 15 years in eastern Denmark. The medical history, brain-MRI, muscle pathology, muscle laminin-α2 expression, and genetic analyses were assessed....... RESULTS: Molecular genetics revealed 2 pathogenic LAMA2 mutations in 5 of 18 CMD and 3 of 128 LGMD patients, corresponding to a LAMA2-mutation frequency of 28% in the CMD and 2.3% in the LGMD cohorts, respectively. CONCLUSIONS: This study demonstrates a wide clinical spectrum of LAMA2-related muscular...
Hemodialysis-related headache.
Sav, Murat Yusuf; Sav, Tansu; Senocak, Elif; Sav, Nadide Melike
2014-10-01
Headache is one of the most frequently encountered neurological symptoms during hemodialysis. According to International Classification of Headache criteria dialysis-related headache was defined as the headache occurring during hemodialysis with no specific characteristic. It resolves spontaneously within 72 hours after the hemodialysis session ends. There are few studies in the literature investigating the clinical features of dialysis headache. The pathophysiology of hemodialysis-related headache is not known, but various triggering factors have been identified, including changes in blood pressure, serum sodium and magnesium levels during hemodialysis sessions, caffeine deprivation and stress. The aim of this article is to evaluate and analyze features of headache in patients undergoing hemodialysis. © 2014 International Society for Hemodialysis.
Offentlighed og Public Relations
Directory of Open Access Journals (Sweden)
Lars Heltoft
1993-09-01
Full Text Available Lars Heltoft, der er en af grundlæggerne af Public Relationsuddannelsen på Roskilde Universitetscenter, kaster i artiklen et kritisk blik på den akademiske forskning i feltet public relations. Selv i nyere udgaver af PR-forskningen - af mange anset for "progressive", f.eks. James Grunings og Jon Whites arbejder - ser Lars Heltoft tydelige spor af PR- professionens selvforståelse og legitimationsbehov. Resultatet er, at den "offentlighed", der burde være kernen i den videnskabelige beskæftigelse med public relations, "forsvinder i den blå luft". Han argumenterer for, at Habermas´ forestilling om "offentlighed" stadig institutionaliserer mulig- heden for kritisk diskurs inden for feltet, samtidig med at han i sproghand- lingsteoretisk perspektiv problematiserer Habermas´ legitimationsbegreb, fordi det undtager private virksomheder og organisationer.
Numerical relativity beyond astrophysics.
Garfinkle, David
2017-01-01
Though the main applications of computer simulations in relativity are to astrophysical systems such as black holes and neutron stars, nonetheless there are important applications of numerical methods to the investigation of general relativity as a fundamental theory of the nature of space and time. This paper gives an overview of some of these applications. In particular we cover (i) investigations of the properties of spacetime singularities such as those that occur in the interior of black holes and in big bang cosmology. (ii) investigations of critical behavior at the threshold of black hole formation in gravitational collapse. (iii) investigations inspired by string theory, in particular analogs of black holes in more than 4 spacetime dimensions and gravitational collapse in spacetimes with a negative cosmological constant.
Paschalidis, Vasileios; Stergioulas, Nikolaos
2017-01-01
Rotating relativistic stars have been studied extensively in recent years, both theoretically and observationally, because of the information they might yield about the equation of state of matter at extremely high densities and because they are considered to be promising sources of gravitational waves. The latest theoretical understanding of rotating stars in relativity is reviewed in this updated article. The sections on equilibrium properties and on nonaxisymmetric oscillations and instabilities in f -modes and r -modes have been updated. Several new sections have been added on equilibria in modified theories of gravity, approximate universal relationships, the one-arm spiral instability, on analytic solutions for the exterior spacetime, rotating stars in LMXBs, rotating strange stars, and on rotating stars in numerical relativity including both hydrodynamic and magnetohydrodynamic studies of these objects.
International Nuclear Information System (INIS)
Cullwick, E.G.
1979-01-01
Einstein published his Special Theory of Relativity in 1905 and in 1915 his General Theory which predicted the bending of light rays passing near the sun. This prediction was apparently confirmed experimentally in 1919 bringing Einstein popular acclaim. Einstein's work is reviewed and the question of whether he was in fact first in the field is examined with especial reference to the work of Maxwell, Lorentz and Poincare. (U.K.)
2012-07-06
German polymath Gauss64 and the Amer- ican mathematician Adrian1 introduced into science the law of frequency of errors, the French physicist ...00-2012 4. TITLE AND SUBTITLE On Allometry Relations 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT ...AR was given by Sarrus and Rameaux.188 Schmidt–Nielsen195 records that this team of a mathematician and a physician reasoned that the heat gener- ated
Corrupt Relational Contracting
Johann Graf Lambsdorff; Sitki Utku Teksoz
2002-01-01
Because corruption must be hidden from the public and is not enforced by courts it entails transaction costs, which are larger than those from legal exchange. This suggests that corrupt contracts are primarily relational contracts where legal exchange serves as a basis for sealing and enforcing corrupt agreements. Legal exchange not only provides for corrupt opportunities, but for the necessary enforcement mechanisms. Examples of such legal exchange are long-term business exchange, belonging ...
Relativity of Visual Communication
Arto Mutanen
2016-01-01
Communication is sharing and conveying information. In visual communication especially visual messages have to be formulated and interpreted. The interpretation is relative to a method of information presentation method which is human construction. This holds also in the case of visual languages. The notions of syntax and semantics for visual languages are not so well founded as they are for natural languages. Visual languages are both syntactically and semantically dense. The density is conn...
Relativity and accelerator engineering
International Nuclear Information System (INIS)
Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni
2017-09-01
From a geometrical viewpoint, according to the theory of relativity, space and time constitute a four-dimensional continuum with pseudo-Euclidean structure. This has recently begun to be a practically important statement in accelerator physics. An X-ray Free Electron Laser (XFEL) is in fact the best, exciting example of an engineering system where improvements in accelerator technology makes it possible to develop ultrarelativistic macroscopic objects with an internal fine structure, and the theory of relativity plays an essential role in their description. An ultrarelativistic electron bunch modulated at nanometer-scale in XFELs has indeed a macroscopic finite-size of order of 10 μm. Its internal, collective structure is characterized in terms of a wave number vector. Here we will show that a four-dimensional geometrical approach, unusual in accelerator physics, is needed to solve problems involving the emission of radiation from an ultrarelativistic modulated electron beam accelerating along a curved trajectory. We will see that relativistic kinematics enters XFEL physics in a most fundamental way through the so-called Wigner rotation of the modulation wave number vector, which is closely associated to the relativity of simultaneity. If not taken into account, relativistic kinematics effects would lead to a strong qualitative disagreement between theory and experiments. In this paper, several examples of relativistic kinematics effects, which are important for current and future XFEL operation, are studied. The theory of relativity is applied by providing details of the clock synchronization procedure within the laboratory frame. This approach, exploited here but unusual in literature, is rather ''practical'', and should be acceptable to accelerator physicists.
Complex manifolds in relativity
International Nuclear Information System (INIS)
Flaherty, E.J. Jr.
1975-01-01
Complex manifold theory is applied to the study of certain problems in general relativity. The first half of the work is devoted to the mathematical theory of complex manifold. Then a brief review of general relativity is given. It is shown that any spacetime admits locally an almost Hermitian structure, suitably modified to be compatible with the indefinite metric of spacetime. This structure is integrable if and only if the spacetime admits two geodesic and shearfree null congruences, thus in particular if the spacetime is type D vacuum or electrified. The structure is ''half-integrable'' in a suitable sense if and only if the spacetime admits one geodesic and shearfree null congruence, thus in particular for all algebraically special vacuum spacetimes. Conditions for the modified Hermitian spacetime to be Kahlerian are presented. The most general metric for such a modified Kahlerian spacetime is found. It is shown that the type D vacuum and electrified spacetimes are conformally related to modified Kahlerian spacetimes by a generally complex conformal factor. These latter are shown to possess a very rich structure, including the existence of Killing tensors and Killing vectors. A new ''explanation'' of Newman's complex coordinate transformations is given. It is felt to be superior to previous ''explanations'' on several counts. For example, a physical interpretation in terms of a symmetry group is given. The existence of new complex coordinate transformations is established: Nt is shown that any type D vacuum spacetime is obtainable from either Schwarzschild spacetime or ''C'' spacetime by a complex coordinate transformation. Finally, some related topics are discussed and areas for future work are outlined. (Diss. Abstr. Int., B)
Relational Demonic Fuzzy Refinement
Tchier, Fairouz
2014-01-01
We use relational algebra to define a refinement fuzzy order called demonic fuzzy refinement and also the associated fuzzy operators which are fuzzy demonic join $({\\bigsqcup }_{\\mathrm{\\text{f}}\\mathrm{\\text{u}}\\mathrm{\\text{z}}})$ , fuzzy demonic meet $({\\sqcap }_{\\mathrm{\\text{f}}\\mathrm{\\text{u}}\\mathrm{\\text{z}}})$ , and fuzzy demonic composition $({\\square }_{\\mathrm{\\text{f}}\\mathrm{\\text{u}}\\mathrm{\\text{z}}})$ . Our definitions and properties are illustrated by some examples using ma...
International Nuclear Information System (INIS)
Strel'tsov, V.N.
1992-01-01
The physical sense of three forms of the relativity is discussed. The first - instant from - respects in fact the traditional approach based on the concept of instant distance. The normal form corresponds the radar formulation which is based on the light or retarded distances. The front form in the special case is characterized by 'observable' variables, and the known method of k-coefficient is its obvious expression. 16 refs
File: International bilateral relations
International Nuclear Information System (INIS)
Feltin, Ch.; Rabouhams, J.; Bravo, X.; Rousseau, M.; Le Breton, S.; Saint Raymond, Ph.; Brigaud, O.; Pertuis, V.; McNair, J.; Sayers, M.R.; Bye, R.; Scherrer, J.
1998-01-01
Since its creation in 1973, the Authority of Safety was assigned missions in the international field with following objectives: to develop information exchanges with its foreign counterpart, to make know and to explain the French approach and practice; to give to concerned countries the useful information on french nuclear facilities situated near the border; This file shows with some examples, how bilateral relations allow to fill up these objectives and how the French Authority got the foreign experience. (N.C.)
Relativity and accelerator engineering
Energy Technology Data Exchange (ETDEWEB)
Geloni, Gianluca [European XFEL GmbH, Schenefeld (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2017-09-15
From a geometrical viewpoint, according to the theory of relativity, space and time constitute a four-dimensional continuum with pseudo-Euclidean structure. This has recently begun to be a practically important statement in accelerator physics. An X-ray Free Electron Laser (XFEL) is in fact the best, exciting example of an engineering system where improvements in accelerator technology makes it possible to develop ultrarelativistic macroscopic objects with an internal fine structure, and the theory of relativity plays an essential role in their description. An ultrarelativistic electron bunch modulated at nanometer-scale in XFELs has indeed a macroscopic finite-size of order of 10 μm. Its internal, collective structure is characterized in terms of a wave number vector. Here we will show that a four-dimensional geometrical approach, unusual in accelerator physics, is needed to solve problems involving the emission of radiation from an ultrarelativistic modulated electron beam accelerating along a curved trajectory. We will see that relativistic kinematics enters XFEL physics in a most fundamental way through the so-called Wigner rotation of the modulation wave number vector, which is closely associated to the relativity of simultaneity. If not taken into account, relativistic kinematics effects would lead to a strong qualitative disagreement between theory and experiments. In this paper, several examples of relativistic kinematics effects, which are important for current and future XFEL operation, are studied. The theory of relativity is applied by providing details of the clock synchronization procedure within the laboratory frame. This approach, exploited here but unusual in literature, is rather ''practical'', and should be acceptable to accelerator physicists.
Ray, J. R.
1982-01-01
Two theories of matter in general relativity, the fluid theory and the kinetic theory, were studied. Results include: (1) a discussion of various methods of completing the fluid equations; (2) a method of constructing charged general relativistic solutions in kinetic theory; and (3) a proof and discussion of the incompatibility of perfect fluid solutions in anisotropic cosmologies. Interpretations of NASA gravitational experiments using the above mentioned results were started. Two papers were prepared for publications based on this work.
International Nuclear Information System (INIS)
Ridgely, Charles T
2010-01-01
Many textbooks dealing with general relativity do not demonstrate the derivation of forces in enough detail. The analyses presented herein demonstrate straightforward methods for computing forces by way of general relativity. Covariant divergence of the stress-energy-momentum tensor is used to derive a general expression of the force experienced by an observer in general coordinates. The general force is then applied to the local co-moving coordinate system of a uniformly accelerating observer, leading to an expression of the inertial force experienced by the observer. Next, applying the general force in Schwarzschild coordinates is shown to lead to familiar expressions of the gravitational force. As a more complex demonstration, the general force is applied to an observer in Boyer-Lindquist coordinates near a rotating, Kerr black hole. It is then shown that when the angular momentum of the black hole goes to zero, the force on the observer reduces to the force on an observer held stationary in Schwarzschild coordinates. As a final consideration, the force on an observer moving in rotating coordinates is derived. Expressing the force in terms of Christoffel symbols in rotating coordinates leads to familiar expressions of the centrifugal and Coriolis forces on the observer. It is envisioned that the techniques presented herein will be most useful to graduate level students, as well as those undergraduate students having experience with general relativity and tensor analysis.
Wittman, David
2018-01-01
Relativity has much to offer for a well-rounded education. Yet books on relativity either assume a strong background in physics and math, aimed at advanced physics students, or, alternatively, offer a broad description with little intellectual challenge. This book bridges the gap. It aims at readers with essentially no physics or math background, who still find it rewarding to think rigorously. The book takes a "thinking tools" approach, by first making readers comfortable with a new thinking tool and then applying it to learn more about how nature works. By the end of the book, readers will have collected a versatile toolbox and will be comfortable using the tools to think about and really understand the intriguing phenomena they may have only heard about, including the twin paradox, black holes, and time travel. End-of-chapter exercises span a range of difficulty, allowing adventurous readers to stretch their understanding further as desired. Students who have studied, or are studying, relativity at a more...
General Relativity and Gravitation
Ashtekar, Abhay; Berger, Beverly; Isenberg, James; MacCallum, Malcolm
2015-07-01
Part I. Einstein's Triumph: 1. 100 years of general relativity George F. R. Ellis; 2. Was Einstein right? Clifford M. Will; 3. Cosmology David Wands, Misao Sasaki, Eiichiro Komatsu, Roy Maartens and Malcolm A. H. MacCallum; 4. Relativistic astrophysics Peter Schneider, Ramesh Narayan, Jeffrey E. McClintock, Peter Mészáros and Martin J. Rees; Part II. New Window on the Universe: 5. Receiving gravitational waves Beverly K. Berger, Karsten Danzmann, Gabriela Gonzalez, Andrea Lommen, Guido Mueller, Albrecht Rüdiger and William Joseph Weber; 6. Sources of gravitational waves. Theory and observations Alessandra Buonanno and B. S. Sathyaprakash; Part III. Gravity is Geometry, After All: 7. Probing strong field gravity through numerical simulations Frans Pretorius, Matthew W. Choptuik and Luis Lehner; 8. The initial value problem of general relativity and its implications Gregory J. Galloway, Pengzi Miao and Richard Schoen; 9. Global behavior of solutions to Einstein's equations Stefanos Aretakis, James Isenberg, Vincent Moncrief and Igor Rodnianski; Part IV. Beyond Einstein: 10. Quantum fields in curved space-times Stefan Hollands and Robert M. Wald; 11. From general relativity to quantum gravity Abhay Ashtekar, Martin Reuter and Carlo Rovelli; 12. Quantum gravity via unification Henriette Elvang and Gary T. Horowitz.
Lectures on general relativity
Papapetrou, Achille
1974-01-01
This book is an elaboration of lecture notes for the graduate course on General Rela tivity given by the author at Boston University in the spring semester of 1972. It is an introduction to the subject only, as the time available for the course was limited. The author of an introduction to General Relativity is faced from the beginning with the difficult task of choosing which material to include. A general criterion as sisting in this choice is provided by the didactic character of the book: Those chapters have to be included in priority, which will be most useful to the reader in enabling him to understand the methods used in General Relativity, the results obtained so far and possibly the problems still to be solved. This criterion is not sufficient to ensure a unique choice. General Relativity has developed to such a degree, that it is impossible to include in an introductory textbook of a reasonable length even a very condensed treatment of all important problems which have been discussed unt...
Intraprofessional relations in nursing.
Duddle, Maree; Boughton, Maureen
2007-07-01
This paper is a report of a study to explore the way in which Registered Nurses relate to and interact with each other in the workplace, and to identify factors that influence nurses' interactions with each other. Intraprofessional relations are an important topic both for nurses and nursing as we face the ongoing challenges of nurse shortages. Poor colleague relationships, together with workplace conflict, cause job dissatisfaction. As a consequence, some nurses leave the profession while others continue working but remain chronically unhappy. An explanatory multiple case study design was adopted. Data were collected from multiple sources on three different wards within one hospital in Australia between July 2005 and January 2006. The workplace can be a difficult place for both very experienced and less experienced nurses, regardless of the clinical environment. Nurses navigate their way in the workplace through a series of complex negotiations with each other and develop skills to assess the potential success of an interaction before approaching another nurse. Some also develop a resilience to conflict in their workplace, accepting it as part of working life. Creation of a more positive work environment requires increased understanding of the way nurses relate to each other and appreciation of the factors in the environment that contribute to conflict and a negative atmosphere. This appreciation is a necessary prerequisite to developing a more satisfying and productive workplace enhancing the recruitment of new nurses and the retention of experienced nurses.
Fernandes, Vera; Santos, Maria Joana; Pérez, Antonio
2016-05-01
Statin therapy has a very important role in decreasing cardiovascular risk, and treatment non-compliance may therefore be a concern in high cardiovascular risk patients. Myotoxicity is a frequent side effect of statin therapy and one of the main causes of statin discontinuation, which limits effective treatment of patients at risk of or with cardiovascular disease. Because of the high proportion of patients on statin treatment and the frequency of statin-related myotoxicity, this is a subject of concern in clinical practice. However, statin-related myotoxicity is probably underestimated because there is not a gold standard definition, and its diagnosis is challenging. Moreover, information about pathophysiology and optimal therapeutic options is scarce. Therefore, this paper reviews the knowledge about the definition, pathophysiology and predisposing conditions, diagnosis and management of statin-related myotoxicity, and provides a practical scheme for its management in clinical practice. Copyright © 2016 SEEN. Published by Elsevier España, S.L.U. All rights reserved.
Teleseismic magnitude relations
Directory of Open Access Journals (Sweden)
Markus Båth
2010-02-01
Full Text Available Using available sets of magnitude determinations, primarily from Uppsala seismological bulletin, various extensions are made of the Zurich magnitude recommendations of 1967. Thus, body-wave magnitude (m and surface-wave magnitudes (M are related to each other for 12 different earthquake regions as well as world-wide. Depth corrections for M are derived for all focal depths. Formulas are developed which permit calculation of M also from vertical component long-period seismographs. Body-wave magnitudes from broad-band and narrow-band short-period seismographs are compared and relations deduced. Applications are made both to underground nuclear explosions and to earthquakes. The possibilities of explosion-earthquake discrimination on the basis of magnitudes are examined, as well as the determination of explosive yield from magnitudes. For earthquakes, relations between magnitudes of main earthquakes and largest aftershocks are investigated. A world-wide station network for more homogeneous magnitude determinations is suggested in order to provide the necessary reference system.
Relativities of fundamentality
McKenzie, Kerry
2017-08-01
S-dualities have been held to have radical implications for our metaphysics of fundamentality. In particular, it has been claimed that they make the fundamentality status of a physical object theory-relative in an important new way. But what physicists have had to say on the issue has not been clear or consistent, and in particular seems to be ambiguous between whether S-dualities demand an anti-realist interpretation of fundamentality talk or merely a revised realism. This paper is an attempt to bring some clarity to the matter. After showing that even antecedently familiar fundamentality claims are true only relative to a raft of metaphysical, physical, and mathematical assumptions, I argue that the relativity of fundamentality inherent in S-duality nevertheless represents something new, and that part of the reason for this is that it has both realist and anti-realist implications for fundamentality talk. I close by discussing the broader significance that S-dualities have for structuralist metaphysics and for fundamentality metaphysics more generally.
International Nuclear Information System (INIS)
Abdel-Rzaeq, Hikmat N.
2004-01-01
Anemia is the most common hematological abnormality in cancer patients is often under-recognized and undertreated. The pathogenesis of cancer anemia is complex and most of time multifactorial; involving factors related to the tumor itself or its therapy. While anemia can be present in a wide range of symptoms, involing almost every organ, it is beleived that it contributes much to cancer-related-fatigue, one of the most common symptoms in cancer patients. In addition there is increasing evidence to suggest that anemia is an independent factor adversely affecting tumor reponse and patient survival. While blood transfusion was the only option to treat cancer related anemia, the use of recombinant human erythropoietin (rHuEPO) is becomig the new standard of care, more so with the recent studies demonstrating the feasibility of a sigle weekly injection .Things are even getting better with the recent approval of a new form of rHuEPO; Darbepoetin an analogue with a 3-fold longer half-life. In addition to its effects in raising homoglobin, several well controlled studies demonstrated decrease in transfusion requirementsand better qualify of life assessed objectively using standard assesments scales. (author)
2015-12-01
communications between the MicroAuto Box and the ground station computer [58]. SimSat users design experiments in the MATLAB® Simulink environment and use an...Guidance, Control, and Dynamics, vol. 35, no. 4, pp. 1094–1103, 2012. [44] Z. Sun, L. Zhang, G. Jin, and X. Yang, “Analysis of inertia dyadic uncertainty
Fast Light Enhanced Active Gyroscopes, Accelerometers and Fiber- Optic Sensors, Phase II
National Aeronautics and Space Administration — The fast-light effect, produced by anomalous dispersion, has emerged as a highly promising mechanism for enhancing the sensitivity of many devices. It is a...
Basic Sensors in iOS Programming the Accelerometer, Gyroscope, and More
Allan, Alasdair
2011-01-01
What really sets the iPhone apart from laptops and PCs is its use of onboard sensors, including those that are location-enabled. This concise book takes experienced iPhone and Mac developers on a detailed tour of iPhone and iPad hardware by explaining how these sensors work, and what they're capable of doing. With this book, you'll build sample applications for each sensor, and learn hands-on how to take advantage of the data each sensor produces. You'll gain valuable experience that you can immediately put to work inside your own iOS applications for the iPhone, iPod touch, and iPad. This b
A Comparison of Gyroscope Digital Models for an Electro-Optical/Infrared Guided Missile Simulation
National Research Council Canada - National Science Library
Waggoner, Brent
2003-01-01
This report was prepared by the author as a Master's thesis which partially fulfilled the requirements for a Master of Science degree in Electrical Engineering from Rose Hulman Institute of Technology, Terre Haute...
From Gyroscopic to Thermal Motion: A Crossover in the Dynamics of Molecular Superrotors
Directory of Open Access Journals (Sweden)
A. A. Milner
2015-09-01
Full Text Available Localized heating of a gas by intense laser pulses leads to interesting acoustic, hydrodynamic, and optical effects with numerous applications in science and technology, including controlled wave guiding and remote atmosphere sensing. Rotational excitation of molecules can serve as the energy source for raising the gas temperature. Here, we study the dynamics of energy transfer from the molecular rotation to heat. By optically imaging a cloud of molecular superrotors, created with an optical centrifuge, we experimentally identify two separate and qualitatively different stages of its evolution. The first nonequilibrium “gyroscopic” stage is characterized by the modified optical properties of the centrifuged gas—its refractive index and optical birefringence, owing to the ultrafast directional molecular rotation, which survives tens of collisions. The loss of rotational directionality is found to overlap with the release of rotational energy to heat, which triggers the second stage of thermal expansion. The crossover between anisotropic rotational and isotropic thermal regimes is in agreement with recent theoretical predictions and our hydrodynamic calculations.
2016-09-01
resistance of one of the known legs can be fine-tuned to nullify gauge resistance perturbation and maintain a balanced bridge. Fig. 13 Die connections...efficient. From tanks and automobiles to unmanned aerial vehicles (UAVs) and robots , the need for improved performance is ubiquitous. Electronic... robots , munitions, and constrained vehicle platforms. Currently, the standard navigation system that the US military uses is GPS. However, one of the
Innovative Fiber-Optic Gyroscopes (FOGs) for High Accuracy Space Applications, Phase II
National Aeronautics and Space Administration — This project aims to develop a compact, highly innovative Inertial Reference/Measurement Unit (IRU/IMU) that pushes the state-of-the-art in high accuracy performance...
Innovative Fiber-Optic Gyroscopes (FOGs) for High Accuracy Space Applications, Phase I
National Aeronautics and Space Administration — NASA's future science and exploratory missions will require much lighter, smaller, and longer life rate sensors that can provide high accuracy navigational...
Modelling of Influence of Hypersonic Conditions on Gyroscopic Inertial Navigation Sensor Suspension
Directory of Open Access Journals (Sweden)
Korobiichuk Igor
2017-06-01
Full Text Available The upcoming hypersonic technologies pose a difficult task for air navigation systems. The article presents a designed model of elastic interaction of penetrating acoustic radiation with flat isotropic suspension elements of an inertial navigation sensor in the operational conditions of hypersonic flight. It has been shown that the acoustic transparency effect in the form of a spatial-frequency resonance becomes possible with simultaneous manifestation of the wave coincidence condition in the acoustic field and equality of the natural oscillation frequency of a finite-size plate and a forced oscillation frequency of an infinite plate. The effect can lead to additional measurement errors of the navigation system. Using the model, the worst and best case suspension oscillation frequencies can be determined, which will help during the design of a navigation system.