A holographic bound on the total number of computations in the visible universe

Information I in holographic imaging of massive particles by star-like screens is shown to represent the probability of detection based on their propagator. Results are derived for screens in the shape of a plane, cube and sphere from unitarity in the exponentially small transition probability for a detection outside. We derive I = 2πΔφ in log 2 bits for the imaging of a particle by a spherical screen at a relative de Broglie phase Δφ. Encoding mass, charge, angular momentum or radiation requires at minimum four bits. Minimal screens at maximal information density hereby recover Reissner–Nordström and extremal Kerr black holes. Applied to the visible Universe, the Hubble flow of galaxies through the cosmological event horizon leaves 10121 computations in the future.

Pattern Center Determination in Electron Backscatter Diffraction Microscopy

The pattern center of an electron backscatter diffraction (EBSD) image indicates the relative position of the image with reference to the interaction volume of the sample. As interest grows in high-resolution EBSD techniques, accurate knowledge of this position is essential for precise interpretation of the EBSD features. In a typical EBSD framework, Kikuchi bands are recorded on a phosphor screen. If the flat phosphor were instead shaped as a sphere, with its center at the specimen's electron interaction volume, then the incident backscattered electrons would form Kikuchi bands on that sphere with parallel band edges centered on great circles. In this article, the authors present a method of pattern center (PC) refinement that maps bands from the planar phosphor onto a virtual spherical screen and measures the deviation of bands from a great circle and from possessing parallel edges. Potential sources of noise and error, as well as methods for reducing these, are discussed. Finally, results are presented on the application of the PC algorithm to two types of simulated EBSD patterns and two experimental setups, and the resolution of the method is discussed.

Realization Technology of A New Virtual Environment for Large-Scale Complex Products Assembly

To deal with the problems of complicated process, difficult operation and low efficiency for large-scale complex products assembly, a new immersive virtual environment (VE) with virtual reality (VR) technology is built in the process of assembly planning and training. The environment is composed of a free walk machine and spherical screen projection system. In this paper, a free walk machine with movement perception function is developed to achieve natural human-computer interaction. And an approach based on two viewpoints match is adopted to improve immersive effect of stereo projection in the projection system. On the basis of that, a geometry calibration method based on Bicubic NURBS(Non-Uniform Rational B-Spline) surface matching target-controlled dot-matrix is proposed to achieve non-distorted image on spherical screen. Finally, the environment is applied in the process of satellite assembly process planning, and the display result shows that the VE development is feasible and valuable.