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Cartesian Coordinate System (cartesian + coordinate_system)
Selected AbstractsAn autonomous tracked vehicle with omnidirectional sensingJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 8 2004R. David Hampton Operation of an autonomous vehicle along a marked path, in an obstacle-laden environment, requires path detection, relative position detection and control, and obstacle detection and avoidance. The design solution of the team from the U.S. Military Academy is a tracked vehicle operating open-loop in response to position information from an omnidirectional mirror, and to obstacle-detection input from the mirror and from a scanning laser. The use of a tracked rather than a wheeled vehicle is the team's open-loop solution to the problem of wheeled-vehicle slippage on wet and sandy surfaces. The vehicleresponds to sensor information from (1) a digital camera-mounted parabolic omnidirectional mirror for visual inputs and (2) a scanning laser for detecting obstacles in relief. Raw sensor data is converted synchronously into a global virtual context, which places the vehicle's center at the origin of a 2-D Cartesian coordinate system. A four-phase process is used to convert the camera's inputs into the data structures needed to reason about the vehicle's position relative to the course. Development of the path plan proceeds incrementally, using a space-sweeping algorithm to identify safe paths along waypoints within the course boundaries. An attempt is made to minimize translation errors by favoring paths which exhibit fewer sharp turns. Integration of Intel's OpenCV computer vision library and the Independent JPEG Group's JPEG library allow for very good encapsulation of the low-level functions needed to do most of the image processing. Ada95 is the language of choice for the majority of the team-developed software, except where needed to interface to motors and sensors. Use of an object-oriented high-level language has been invaluable in leveraging the efforts of previous years' development activities, and for maximizing the ability to log or otherwise respond to anomalous behavior. © 2004 Wiley Periodicals, Inc. [source] A general expression of the polarization factor for multi-diffraction processesACTA CRYSTALLOGRAPHICA SECTION A, Issue 3 2010Kiyoaki Tanaka A general expression of the polarization factor of multi-diffracted beams is formulated. By assigning the diffracted beam direction of each diffraction process as the y axis of a Cartesian coordinate system, the polarization factor of multi-diffraction processes can be easily calculated for polarized and unpolarized beams without being limited by the number of diffraction processes. The method can be applied to processes with more than three scattering events such as multiple diffraction and extinction. [source] The piezoelectric effect of second order in stress or strain: its form for crystals and quasicrystals of any symmetryACTA CRYSTALLOGRAPHICA SECTION A, Issue 6 2007Hans Grimmer The restrictions on the coefficients describing physical effects depend on the orientation of the symmetry elements of the crystal or quasicrystal with respect to the Cartesian coordinate system employed. They are given for the piezoelectric effect of second order in stress or strain for all the orientations that can be expressed by the sequence of elements in the Hermann,Mauguin symbol of the point group. In the literature, the restrictions are usually given only for a particular orientation, which sometimes is not specified. [source] Multi-sensor track-to-track fusion via linear minimum variance sense estimatorsASIAN JOURNAL OF CONTROL, Issue 3 2008Li-Wei Fong Abstract An integrated approach that consists of sensor-based filtering algorithms, local processors, and a global processor is employed to describe the distributed fusion problem when several sensors execute surveillance over a certain area. For the sensor tracking systems, each filtering algorithm utilized in the reference Cartesian coordinate system is presented for target tracking, with the radar measuring range, bearing, and elevation angle in the spherical coordinate system (SCS). For the local processors, each track-to-track fusion algorithm is used to merge two tracks representing the same target. The number of 2-combinations of a set with N distinct sensors is considered for central track fusion. For the global processor, the data fusion algorithms, simplified maximum likelihood (SML) estimator and covariance matching method (CMM), based on linear minimum variance (LMV) estimation fusion theory, are developed for use in a centralized track-to-track fusion situation. The resulting global fusers can be implemented in a parallel structure to facilitate estimation fusion calculation. Simulation results show that the proposed SML estimator has a more robust capability of improving tracking accuracy than the CMM and the LMV estimators. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] RNA secondary structure 2D graphical representation without degeneracyINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 8 2006Bo Liao Abstract A two-dimensional graphical representation (2DGRR) of RNA secondary structures using a two Cartesian coordinates system has been derived for mathematical denotation of RNA structure. The 2DGRR resolves structure degeneracy and avoids loss of information and the limitation that different structures correspond to the same curve. The RNA pseudo-knots also can be represented as 2D graphical representations. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] | |||||||||||||