Method of rotation angle measurement in machine vision based on calibration pattern with spot array.
We propose a method of rotation angle measurement with high precision in machine vision. An area scan CCD camera, imaging lens, and calibration pattern with a spot array make up the measurement device for measuring the rotation angle. The calibration pattern with a spot array is installed at the rotation part, and the CCD camera is set at a certain distance from the rotation components. The coordinates of the spots on the calibration pattern is acquired through the vision image of the calibration pattern captured by the CCD camera. At the initial position of the calibration pattern, the camera is calibrated with the spot array; the mathematical model of distortion error of the CCD camera is built. With the equation of coordinate rotation measurement, the rotation angle of the spot array is detected. In the theoretic simulation, noise of different levels is added to the coordinates of the spot array. The experiment results show that the measurement device can measure the rotation angle precisely with a noncontact method. The standard deviation of rotation angle measurement is smaller than 3 arc sec. The measurement device can measure both microangles and large angles.
Modeling of a mobile setup by networks for object contouring
A model of a mobile setup for shape reconstruction is presented. In this technique, the contouring is performed by laser scanning and image processing. The devices of this setup can be moved to examine occluded areas and small details. The modeling of the mobile setup is carried out by an approximation network, which produces an equation that computes the object dimensions from the deformation of a laser line and the camera position. Also, the geometric parameters of the optical system are deduced, based on the network and image processing. This model improves the performance and the accuracy of the reconstruction system, because all steps of the contouring are performed by computer algorithms. In this manner, the errors of the physical measurements are not passed to the reconstruction system. This procedure represents a contribution to the methods of contouring based on laser scanning. To describe the accuracy, a root mean square of error is calculated with respect to a contact method. This technique has been tested with real objects, and experimental results are presented. Also, the processing time is discussed.
Nuclear sphingolipid metabolism.
Nuclear lipid metabolism is implicated in various processes, including transcription, splicing, and DNA repair. Sphingolipids play roles in numerous cellular functions, and an emerging body of literature has identified roles for these lipid mediators in distinct nuclear processes. Different sphingolipid species are localized in various subnuclear domains, including chromatin, the nuclear matrix, and the nuclear envelope, where sphingolipids exert specific regulatory and structural functions. Sphingomyelin, the most abundant nuclear sphingolipid, plays both structural and regulatory roles in chromatin assembly and dynamics in addition to being an integral component of the nuclear matrix. Sphingosine-1-phosphate modulates histone acetylation, sphingosine is a ligand for steroidogenic factor 1, and nuclear accumulation of ceramide has been implicated in apoptosis. Finally, nuclear membrane-associated ganglioside GM1 plays a pivotal role in Ca(2+) homeostasis. This review highlights research on the factors that control nuclear sphingolipid metabolism and summarizes the roles of these lipids in various nuclear processes.