327 results about "Gravity gradient" patented technology

A method for geographical surveying includes the steps of determining an observation grid comprising observation points above a solution volume in the ground; making gravitational measurements at the observation points over a survey area; compiling a matrix having elements relating a set of gravitational accelerations and gravity gradient values at the points to the mass values for volume elements in the solution volume; and calculating the three-dimensional density distribution of the volume under the survey area based on the gravitational measurements and the inverse of the matrix. By measuring the magnetic field and gradient at the observation points, the three-dimensional magnetic susceptibility distribution of the volume under the survey area can be determined.

Gravity gradiometers (or gravity gradient instrument, GGI) measure one or more components of the gradient of gravity which is expressed as the gradient of a gravity vector. One or more feedback loops extend from the instrument output to one or more of the accelerometers (1-4) to compensate for errors. The feedback loops include one or more inputs in addition to the instrument output. The additional inputs include signals representing one or more of: components of attitude, velocity and acceleration, the physical environment and flight conditions, taken alone or in combination.

A gradiometer is disclosed which has a pair of sensor bars 41, 43 supported in housings 45, 47. Transducers 71 are located adjacent the bars 41, 43 to detect movement of the bars in response to the gravity gradient tensor. At least one of the transducers 71 comprises a first coil 510 and a second coil 516 arranged in parallel and a switch 362 for proportioning current between the coils 510 and 516 so as to create a virtual coil at a position D between the coils 510 and 516.

The present invention provides a gravity gradiometer for measuring components of the gravity gradient tensor. The gravity gradiometer comprises at least one sensor mass for movement in response to a gravity gradient and a pivotal coupling enabling the movement of the at least one sensor mass about an axis. Further, the gravity gradiometer comprises a constant charge capacitor that is arranged so that the movement of the at least one sensor mass generates a change in a voltage across the constant charge capacitor.

A gravity gradiometer is disclosed which comprises a pair of sensor masses 41, 43 arranged in housings 45, 47. Transducers 71 are provided for measuring movement of the sensor masses in response to the gravity gradient tensor. The masses are supported for movement by a flexure web 59 between the mass and a support and a stop comprises a pair of abutment services 554, 555 and 558, 559 defined by a cut 550 prevent movement of the sensor masses 41, 43 beyond the elastic limit of the flexure web 59.

A gravity gradiometer is disclosed which has sensor masses in the forms of bars 41 and 43 arranged orthogonal to one another and transducers for providing an output signal indicative of movement of the bars in response to changes in the gravity gradient tensor. The transducers are formed from thin film structure having a first layer forming a fine pitch coil 510 and a second layer forming a coarse pitch coil 511. The layers are separated by an insulating layer. The coarse pitch coil 511 forms a transformer for stepping up the current flowing through the fine pitch coil 510 and the coarse pitch coil 511 supplies current to a SQUID device 367.

The present invention provides a gravity gradiometer which comprises at least one sensor mass suspended by a coupling which enables movement of the at least one sensor mass about an axis in response to a gravity gradient. Further, the gravity gradiometer comprises at least one transducer for generating an electrical signal in response to the movement of the at least one sensor mass relative to a component of the transducer and for influencing the movement of the at least one sensor mass. The gravity gradiometer also comprises electrical circuitry for receiving the electrical signal from the at least one transducer and for directing an actuating signal to the at least one transducer so that in use the at least one transducer functions as sensor and actuator.

The invention discloses an attitude control method. The attitude control method comprises the following procedures that the on-satellite time influencing the satellite attitude precision is aligned through a second pulse signal; a satellite sensor error used for satellite attitude measurement is corrected in real time; the gravity gradient disturbance torque of an oblique flying satellite is compensated through a dynamics coupling relationship; the satellite flexibility is restrained through an input forming control method in the attitude controlling process; the attitude control law of an angular velocity feedforward instruction is increased through position and speed double loops and a position correcting loop to achieve high-precision and high-stability attitude guidance control; and quick attitude maneuver of the large-inertia satellite is achieved through a saturated sliding mold structural control algorithm. The attitude control method has the advantages that the computing method is simple, control is flexible, the attitude control method can be applied to attitude control of the large-inertia large-flexible oblique flying satellite, the property of the satellite is greatly improved, and researching and manufacturing cost of satellite hardware is reduced.

A method and apparatus for maneuvering a satellite in orbit to alternately optimize the collection of solar energy and to take sensor data of terrestrial objects is disclosed The longitudinal axis of a large payload package is oriented perpendicular to the orbital plane to minimize the disturbance torque due to gravity gradient, and to allow simple rotation about the axis for attitude change between optimal Sun and optimal ground coverage.

The invention discloses a vertical gravity gradient measuring sensor based on an atom interference effect, and belongs to the technical field of gravity surveying. The sensor comprises a first unit device (A) and a second unit device (B) of the same structures, and is characterized in that a first vacuum container (1.1) and a second vacuum container (1.2) are connected end to end in the mode that central axes are overlapped in the gravity direction to form a vacuum container (1), and the hollow part inside the first vacuum container (1.1) and the hollow part inside the second vacuum container (1.2) are communicated into a whole; two Raman laser beam emitters (7) are respectively arranged on the vacuum container (1) along the central axis of the gravity field direction, and the Raman laser beam emitters (7) carry out opposite emitting and point to the preparation regions of cold atomic groups (c), and the two unit devices share the pair of Raman laser beam emitters (7). The vertical gravity gradient measuring sensor enables noise and deviation from environment and Raman laser phase positions to be offset in a common-mode mode, and reduces the complexity, the size, the mass and the power consumption of a physical system.

The invention discloses a household garbage crushing sorting system. The sorting system consists of a quantitative feeding device, a magnetic separation device, a gravity gradient sorting device, a pendulum type crushing device, an air separation device, a needle selection device and a material conveying device. The sorting system is compact in structure, can achieve continuous production, is high in production efficiency, simple to operate, safe and reliable, and can divide urban household garbage into decayable organic matter, combustible wastes, metal, glass and light recoverable matter, so that the urban household garbage can be sufficiently utilized as a resource, and the sorting system has very high environmental benefit and social benefit simultaneously.

A methods and apparatus for an improved gravity gradiometer are disclosed.

Abstract of Disclosure A method of determining changes in the boundary interface in a sub-surface oil reservoir between the to-be-recovered oil and a driveout fluid, such as steam, uses time-displaced gravity gradient measurements to provide an indication of the changes in the gravity gradient over time. The measured data are subject to simulated annealing optimization to find the global minimum that best represents the observed values within the solution space. The optimization process includes establishing an appropriately constrained model of the oil reservoir and a quantized set of mathematically related parameters that define the model. Successive models are perturbed and evaluated from a figure of merit standpoint until a global minimum that best describes the measured time-lapse data is found.

The invention provides a gravity-gradient-invariant-based method for estimating an orbit element. The method comprises: step one, carrying out preparation work; step two, carrying out decomposition of an ideal gravity gradient tensor under an east-noth-up (ENU) coordinate system and obtaining feature values; step three, solving decomposition of a measuring epoch J2 model gravity field tensor under the ENU coordinate system and obtaining feature values; step four, solving all measuring epochs r and phi by using feature values of a J2 gravity gradient matrix; step five, calculating an initial orbit element by using the r and phi; and step six, carrying out orbit element smoothing. Therefore, with utilization of the gravity gradient matrix invariant information measured during the satellite operating process, a geometrical distance between the satellite and the earth's core and the latitude of the earth's core are obtained by iterative solution; a measurement equation that uses a semi-major axis, an eccentricity ratio, an orbit inclination angle, a perigee depression angle, and a true anomaly in an orbital element as state parameters is provided by using an obtained data as an observed quantity; and a perturbation kinetic equation of the orbital element is introduced innovatively and five orbital elements are estimated by using a batching least square method. The gravity-gradient-invariant-based method has advantages of high autonomous degree, high anti-interference capability, and low building cost and the like and has advantages that the traditional method does not have in the deep space exploration field.

The invention relates to a method for precisely measuring the earth gravitational field, in particular to a method for inverting the earth gravitational field by using a variance-covariance diagonal tensor principle. The method comprises the following steps of: establishing a cumulative geoidal surface error model on the basis of satellite gravity gradient variance-covariance diagonal tensor principle; accurately and rapidly inverting the earth gravitational field by using the satellite gravity gradient measurement data of a spaceborne gravity gradiometer; and developing requirement argumentation on a GOCE (Gravity Field and Steady-State Ocean Circulation Explorer)-II satellite gravity gradient system by using the satellite orbit altitude and the precision index of the satellite gravity gradiometer. The method disclosed by the invention is high in inversion precision of the earth gravitational field, high in inversion speed of the satellite gravity gradient, explicit in physical content of a satellite observation equation, capable of easily developing the requirement analysis of the satellite gravity gradient system and low in requirement on computer performances. Therefore, the method for inverting the earth gravitational field by using the variance-covariance diagonal tensor principle is an effective method for resolving the earth gravitational field with high precision and high spatial resolution.

The invention discloses a method utilizing a gravity gradiometer to measure gravitation gradients. According to the method, an expression is output according to the gravitation gradients acted on the gravity gradiometer by a gravitation generating device, a track having the most obvious changes of the theoretical gravitation gradients in space is determined, then the gravitation generating device moves on the most optimized track derived in theory, the gravitation gradients caused by the gravitation generating device on various points of the track are measured, and stored and processed through signals, the measured gravitation gradients and the theoretical gravitation gradients are compared for judgment, and measuring accuracy and the resolution ratio of the gravity gradiometer are obtained. The method can be used for conducting accuracy measurement, parameter standardization and error correction of the gravity gradiometer, and fill the measuring blank of the gravitation gradients inland.

The invention relates to a structure-constrained two-dimensional gravity gradient and magnetotelluric joint inversion method. The method includes the steps of establishing a multi-component gravity gradient and magnetotelluric joint inversion objective function, calculating forward responses and Jacobian matrixes of a gravity gradient method and a magnetotelluric method, and obtaining a fitting difference value between forward response values and observed data. The multi-component gravity gradient method is introduced into joint inversion to replace a conventional gravity exploration method. The magnetotelluric method provides abundant frequency information and large exploration depth. The introduction of the method into the joint inversion effectively overcomes defects of poor gravity gradient and poor gravity vertical resolution and better enables a density inversion model to be recovered. The method of the invention is a joint inversion method based on cross gradient structure coupling. Compared with single inversion and other conventional physical coupling inversion methods, the method of the invention does not depend on rock physical relationships and can better recover a realmodel structure, whether in physical property numerical value or in geometric space shape.

A full-tensor, gravity gradient measuring system is disclosed that is based on atom interferometry. Each axis in the three-axis measuring system is served by a different gravity gradiometer, where each gradiometer comprises three pairs of atom interferometric (AI) accelerometers. The accelerometers in each pair are mounted on opposite sides of the gradiometer's rotation axis from each other. The three AI accelerometer pairs are step-rotated, instead of being continuously rotated, thereby providing enhanced signal-to-noise performance. The three gradiometers in the overall measuring system are mounted orthogonally with respect to one another on a local-level platform, in order to achieve a full-tensor measuring system. The measuring system can be step-rotated as an overall unit around an axis perpendicular to a local level reference. The multiple levels of stepped rotation, as enabled by the atom interferometry being utilized, yields improved results with lower costs than what is achievable with some prior-art techniques.