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Petroleum Geophysical Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
Absolute gravity is not required in geological survey. Its determination is not only difficult but also time consuming. The determination of ‘relative gravity’ or the ‘gravity anomaly’ is needed for the interpretation and correlation of the subsurface targeted small area in terms of rock features including oil/gas. Relative anomaly is the difference in the gravity of the region (background) from that of the targeted survey location area. If the regional gravity (normal/standard gravity) is higher than that at the targeted area, the difference is referred to as a positive anomaly, and if the regional gravity is smaller it is a negative anomaly.
Geophysical Applications
Published in Stephen M. Testa, Geological Aspects of Hazardous Waste Management, 2020
Two basic types of gravity surveys exist: standard gravity and microgravity. A standard gravity survey uses widely spaced stations (100- to 1000-ft intervals) and a standard gravity meter to cover large distances (typically via use of an airplane). A microgravity survey uses a microgravimeter which is capable of measuring small differences in the gravitational field for delineating and mapping local anomalies (i.e., bedrock channels, fractures, cavities, etc.).
Fluid Mechanics
Published in Michael A. Crabtree, The Concise Industrial Flow Measurement Handbook, 2019
Consequently, for a body having a mass of 1 kg: F = (1 kg) · (9.807 m/s2) = 9.807 N where 9.807 m/s2 = standard gravity close to Earth in the SI system. ◄
Minimum lap time trajectory optimisation of performance vehicles with four-wheel drive and active aerodynamic control
Published in Vehicle System Dynamics, 2023
Pieter de Buck, Joaquim R. R. A Martins
The normal forces of the tires are defined as where and are the aerodynamic downforce generated by the vehicle and rear wing, respectively. The vehicle's centre of pressure (CoP) coincides with the centre of gravity. The rear wing forces act directly at the rear wheels, effectively moving the centre of pressure aft, depending on the vehicle velocity. Velocity-dependent lift and drag coefficient curves for the vehicle were obtained from Limebeer and Perantoni [25], where the vehicle's frontal area is set to 1 m. g is standard gravity. The height of the CoG off the ground is h. χ is the front-to-rear roll balance.
Biomechanical effects of a halo orthotic on a pediatric anthropomorphic test device in a simulated frontal motor vehicle collision
Published in Traffic Injury Prevention, 2022
Eric A. Sribnick, Julie A. Mansfield, Carrie Rhodes, Vera Fullaway, John H. Bolte
Kinematics were recorded using high speed video (1000 frame/s) and analyzed using TEMA Motion software (v3.8, Image Systems AB, Linköping, Sweden). Sample video from all tests are available as Appendix C. Head and knee displacement data were calculated from the initial position of each test. Biomechanical data were obtained from the ATD from the following instrumentation: head and chest accelerometers (Meggitt Sensing Systems, Irvine, CA), head angular rate sensors (Diversified Technical Systems, Seal Beach, CA), a six-axis upper neck load cell (Humanetics), and chest linear potentiometer (Servo Instrument Corporation, Baraboo, WI). Data from ATD channels were processed in accordance with Society of Automotive Engineers (SAE) J211 guidelines (SAE International 2007). For analysis of the resulting forces, biomechanical injury thresholds are shown as a reference (Mertz et al. 2016). Sled acceleration is reported as standard gravity (g), and sled velocity is reported as miles per hour (mph). Metrics of sled pulses are reported as mean plus/minus standard deviation, and coefficient of variation (CV) is also reported. Statistical analysis was performed using GraphPad Prism (version 8.2, San Diego, CA).
Performance evaluation of low-cost GPS/INS in-motion alignment model under ECEF frame
Published in International Journal of Image and Data Fusion, 2020
Yunrui Zhang, Qiuzhao Zhang, Chun Ma
As a kind of self-aid and recursive navigation system, INS must realise initial alignment before navigation and appropriate misalignment angle model is the basis of accurate initial alignment. The traditional initial alignment includes static base coarse alignment and fine alignment. The initial alignment method of high precision IMU is different from that of low cost IMU. For high precision IMU, the unknown attitude angle errors converge to small angle errors during coarse alignment. By measuring gravity and earth velocity, compared with standard gravity and earth velocity, the error can be analysed on static base. Under the premise of small attitude error, fine alignment based on inertial navigation error equation can eliminate the residual error, which can be carried out on the stationary base by using gyro compassing theory or with the aid of other sensors Savage (2000).