China 
Africa 
Explore chapters and articles related to this topic
Rigid Body Motion Capturing by Means of Wearable Inertial and Magnetic MEMS Sensor Assembly
Published in Laurent A. Francis, Krzysztof Iniewski, Novel Advances in Microsystems Technologies and Their Applications, 2017
Hassen Fourati, Noureddine Manamanni, Lissan Afilal, Yves Handrich
A rigid body is considered as a solid formed from a finite set of material points with deformable volume (Goldstein 1980). Generally, the rigid body attitude represents the direction of its principal axes relative to a reference coordinate system, and its dynamics expresses the change of object orientation. In the navigation field, the attitude estimation problem requires the transformation of measured and computed quantities between various frames. The rigid body attitude is based on measurements gained from sensors attached to this latter. Indeed, inertial sensors (accelerometer, gyroscope, etc.) are attached to the body platform and provide inertial measurements expressed relative to the instrument axes. In most systems, the instrument axes are nominally aligned with the body-platform axes. Since the measurements are performed in the body frame, we describe in Figure 17.2 the orientation of the body-fixed frame B(XB, YB, ZB) with respect to the Earth-fixed frame N(XN, YN, ZN), which is tangent to the Earth’s surface (local tangent plane, LTP). This local coordinate is particularly useful to express the attitude of a moving rigid body on the surface of the Earth (Grewal et al. 2001). The XN-axis points true north. The ZN-axis points towards the interior of the Earth, perpendicular to the reference ellipsoid. The YN-axis completes the right-handed coordinate system, pointing east (NED: north, east, down).
Mechanics of Structures and Their Analysis
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
The principal axis is the axis in which the inertial moment is maximum or minimum and the inertial product is zero. The principal plane is a stress property, whereas the principal axis is a moment of inertia property. There is no relationship between the principal axis and the principal plane.
High-resolution spectroscopy near the continuum limit: the microwave spectrum of trans-3-bromo-1,1,1,2,2-pentafluoropropane
Published in Molecular Physics, 2019
Frank E. Marshall, Nicole Moon, Thomas D. Persinger, David J. Gillcrist, Nelson E. Shreve, William C. Bailey, G. S. Grubbs II
However, these new possibilities also come with some inherent problems. One problem is that of spectral density. CP-FTMW spectroscopy, being a pure rotational spectroscopy technique, produces spectra that are various combinations of rotational constants based on the dipole moments of the molecular system of study. These rotational constants are inversely proportional to the moments of inertia about each principal axis. Furthermore, the intensities of the resultant spectra are governed by the system's statistical mechanics and dipole moment vector components in the principal axis system. As systems become large, rotational constants become small, creating dense spectra that are generally weaker in intensity, making assignment a challenging process. This is particularly true with chiral tagging experiments where the systems are governed by complexation chemistry, size, and number of produced diastereomers. Furthermore, additional angular momenta (like quadrupole coupling nuclei) can further split and spread spectra out making assignment, even with automated routines, a very difficult task.