NASA Tech Briefs, July/August 1986

Topic include: NASA TU Serv1ces; New Product Ideas; Electronic Components and Circuits; Electronic Systems; Materials; Computer Programs; Mechanics; Physical Sciences; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences.

Artificial Intelligence for Multimedia Signal Processing

Artificial intelligence technologies are also actively applied to broadcasting and multimedia processing technologies. A lot of research has been conducted in a wide variety of fields, such as content creation, transmission, and security, and these attempts have been made in the past two to three years to improve image, video, speech, and other data compression efficiency in areas related to MPEG media processing technology. Additionally, technologies such as media creation, processing, editing, and creating scenarios are very important areas of research in multimedia processing and engineering. This book contains a collection of some topics broadly across advanced computational intelligence algorithms and technologies for emerging multimedia signal processing as: Computer vision field, speech/sound/text processing, and content analysis/information mining

Simulation of the Quantum Ising Model in an Ion Trap

In a proof-of-principle experiment, we simulate the dynamics of a quantum spin system in an ion trap. Following a theoretical proposal by D. Porras and I. Cirac, we use a system of ground state cooled trapped ions to simulate and study the dynamics of a quantum-mechanical system, or more precisely, the dynamics of a quantum spin Hamiltonian. We implement the smallest non-trivial quantum spin Hamiltonian, the quantum Ising model for two spins. Each spin is represented by two hyperfine ground levels of trapped 25Mg+ ions. The interaction with an external magnetic field is simulated by coherently coupling these hyperfine levels via laser and radiofrequency radiation. The spin-spin interaction is simulated via optical dipole forces, where the effective interaction is mediated by the phonons of the linear ion chain. We demonstrate the adiabatic evolution from a paramagnetically ordered system to ferromagnetic order. The final state of this adiabatic transition is a superposition state of the two degenerate spin configurations of ferromagnetic order Psi_final = 1/sqrt(2) (|up up> + |down down>) with a quantum magnetisation of 98%. We also show the transition from paramagnetic to antiferromagnetic order with the final state Psi_final = 1/sqrt(2) (|up down> + |down up>). Moreover, we prove that this transition which is to become a quantum phase transition in the thermodynamic limit of infinitely many spins, is driven by quantum fluctuations which dominate the dynamics of such systems at the absolute zero-point of temperature rather than thermal fluctuations which are absent at 0 K. This is verified by the fact that the final state of our adiabatic evolution is entangled, close to a Bell state at a fidelity exceeding 88%. The set of tools presented in this thesis might serve as a basis for larger scale quantum simulations which might help in gaining insight into many-particle effects that are intractable on classical computers such as spin frustration in triangular lattices or high-Tc superconductivity.Mit der vorliegenden Arbeit demonstrieren wir die Realisierbarkeit von Quantensimulationsexperimenten in einer Ionenfalle. Wir setzen hiermit einen experimentellen Vorschlag von D. Porras und I. Cirac um, in dem ein grundzustandsgekühltes System mehrerer Ionen in einer Falle dazu herangezogen wird, quantenmechanische Systeme, genauer gesagt, Quantenspin-Hamilton-Operatoren zu simulieren. Wir simulieren das einfachste nicht-triviale System, das Quanten-Ising-Modell für zwei Spins. Die Spins werden durch Hyperfeinzustände individueller Magnesiumionen kodiert. Durch kohärente Kopplung mit Hilfe von Laser- und Radiofrequenzfeldern lassen sich externe magnetische Felder simulieren. Die Isingwechselwirkung wird durch optische Dipolkräfte realisiert, die mit Hilfe der Phononen der Spinkette in eine zustandsabhängige Kraft übersetzt werden. Wir zeigen den Übergang von einem paramagnetisch geordneten System zweier Spins zu einem Ferromagneten. Der Endzustand dieser adiabatischen Simulation ist durch eine kohärente Überlagerung der beiden entarteten ferromagnetischen Ausrichtungen der Spin Psi_final = 1/sqrt(2) (|up up> + |down down>) gegeben, wobei wir eine Quantenmagnetisierung des Systems von 98% erreichen. Desweiteren zeigen wir den Übergang vom selben Ausgangszustand zur antiferromagnetischen Phase Psi_final = 1/sqrt(2) (|up down> + |down up>)). Durch die Tatsache, daß der Endzustand nach der Simulation in hohem Maße deterministisch verschränkt ist, verifizieren wir, daß dieser Übergang allein durch Quantenfluktuationen und nicht durch thermische Fluktuationen getrieben wird. Im thermodynamischen Limes unendlich vieler Teilchen wird dieser Übergang zu einem Quantenphasenübergang. Man erhofft, durch derartige Experimente, ein tieferes Verständnis für Vielteilchen-Quantensysteme, die mit klassischen Computern nicht lösbar sind, zu gewinnen, und damit Effekte wie Spin-Frustration in Dreiecks-Gittern oder Hochtemperatursupraleitung und deren Dynamik besser zu verstehen

Tracking the Temporal-Evolution of Supernova Bubbles in Numerical Simulations

The study of low-dimensional, noisy manifolds embedded in a higher dimensional space has been extremely useful in many applications, from the chemical analysis of multi-phase flows to simulations of galactic mergers. Building a probabilistic model of the manifolds has helped in describing their essential properties and how they vary in space. However, when the manifold is evolving through time, a joint spatio-temporal modelling is needed, in order to fully comprehend its nature. We propose a first-order Markovian process that propagates the spatial probabilistic model of a manifold at fixed time, to its adjacent temporal stages. The proposed methodology is demonstrated using a particle simulation of an interacting dwarf galaxy to describe the evolution of a cavity generated by a Supernov

Statistical Consequences of Fat Tails: Real World Preasymptotics, Epistemology, and Applications

The monograph investigates the misapplication of conventional statistical techniques to fat tailed distributions and looks for remedies, when possible. Switching from thin tailed to fat tailed distributions requires more than "changing the color of the dress". Traditional asymptotics deal mainly with either n=1 or $n=\infty$, and the real world is in between, under of the "laws of the medium numbers" --which vary widely across specific distributions. Both the law of large numbers and the generalized central limit mechanisms operate in highly idiosyncratic ways outside the standard Gaussian or Levy-Stable basins of convergence. A few examples: + The sample mean is rarely in line with the population mean, with effect on "naive empiricism", but can be sometimes be estimated via parametric methods. + The "empirical distribution" is rarely empirical. + Parameter uncertainty has compounding effects on statistical metrics. + Dimension reduction (principal components) fails. + Inequality estimators (GINI or quantile contributions) are not additive and produce wrong results. + Many "biases" found in psychology become entirely rational under more sophisticated probability distributions + Most of the failures of financial economics, econometrics, and behavioral economics can be attributed to using the wrong distributions. This book, the first volume of the Technical Incerto, weaves a narrative around published journal articles

Finite elements software and applications

The contents of this thesis are a detailed study of the software for the finite element method. In the text, the finite element method is introduced from both the engineering and mathematical points of view. The computer implementation of the method is explained with samples of mainframe, mini- and micro-computer implementations. A solution is presented for the problem of limited stack size for both mini- and micro-computers which possess stack architecture. Several finite element programs are presented. Special purpose programs to solve problems in structural analysis and groundwater flow are discussed. However, an efficient easy-to-use finite element program for general two-dimensional problems is presented. Several problems in groundwater flow are considered that include steady, unsteady flows in different types of aquifers. Different cases of sinks and sources in the flow domain are also considered. The performance of finite element methods is studied for the chosen problems by comparing the numerical solutions of test problems with analytical solutions (if they exist) or with solutions obtained by other numerical methods. The polynomial refinement of the finite elements is studied for the presented problems in order to offer some evidence as to which finite element simulation is best to use under a variety of circumstances

Computational Optimizations for Machine Learning

The present book contains the 10 articles finally accepted for publication in the Special Issue “Computational Optimizations for Machine Learning” of the MDPI journal Mathematics, which cover a wide range of topics connected to the theory and applications of machine learning, neural networks and artificial intelligence. These topics include, among others, various types of machine learning classes, such as supervised, unsupervised and reinforcement learning, deep neural networks, convolutional neural networks, GANs, decision trees, linear regression, SVM, K-means clustering, Q-learning, temporal difference, deep adversarial networks and more. It is hoped that the book will be interesting and useful to those developing mathematical algorithms and applications in the domain of artificial intelligence and machine learning as well as for those having the appropriate mathematical background and willing to become familiar with recent advances of machine learning computational optimization mathematics, which has nowadays permeated into almost all sectors of human life and activity

Analysis methods for airborne radioactivity

High-resolution gamma-ray spectrometry is an analysis method well suitable for monitoring airborne radioactivity. Many of the natural radionuclides and a majority of anthropogenic nuclides are prominent gamma-ray emitters. With gamma-ray spectrometry different radionuclides are readily observed at minute concentrations that are far from health hazards. The gamma-ray spectrometric analyses applied in air monitoring programmes can be divided into particulate measurements and gas measurements. In this work, methods applicable for particulate sample analysis have been presented, implemented in analysis software, and evaluated with a wide variety of cases. Our goal has been to develop a collection of tools that enables a complete quantitative explanation of all components of a measured gamma-ray spectrum with a minimum of user intervention. In a high-resolution spectrum, all essential information is contained in the peaks. Most of them are full-energy peaks that can be explained with gamma-ray lines in a reference library. Among the full-energy peaks, however, there are annihilation escape peaks, X-ray escape peaks, coincidence sum peaks, and random sum peaks that are not tabulated. Calculation methods for these special peaks are presented, implemented in SHAMAN, and evaluated in this work. Expert system SHAMAN combines a comprehensive ENSDF-based reference library with an inference engine that applies pruning rules to select the acceptable candidate nuclides, utilizing a collection of calculational methods. Its performance with air filter spectra is evaluated in this work with four different spectrum sets. The performance of SHAMAN is also benchmarked against another identification software in completely automated analysis. In summary, expert system SHAMAN is well applicable at any organization where environmental radioactivity is monitored. The system can also be utilized in other applications, but the current rule base has been tailored most comprehensively for air filter spectra. The analysis capabilities of the system can be improved in other applications of gamma-ray spectrometry by tuning the analysis parameters of the system. Naturally, there is still room for improvement in the methodology of SHAMAN, but already with the currently implemented features it is a reliable expert system for nuclide identification

The Fifteenth Marcel Grossmann Meeting

The three volumes of the proceedings of MG15 give a broad view of all aspects of gravitational physics and astrophysics, from mathematical issues to recent observations and experiments. The scientific program of the meeting included 40 morning plenary talks over 6 days, 5 evening popular talks and nearly 100 parallel sessions on 71 topics spread over 4 afternoons. These proceedings are a representative sample of the very many oral and poster presentations made at the meeting.Part A contains plenary and review articles and the contributions from some parallel sessions, while Parts B and C consist of those from the remaining parallel sessions. The contents range from the mathematical foundations of classical and quantum gravitational theories including recent developments in string theory, to precision tests of general relativity including progress towards the detection of gravitational waves, and from supernova cosmology to relativistic astrophysics, including topics such as gamma ray bursts, black hole physics both in our galaxy and in active galactic nuclei in other galaxies, and neutron star, pulsar and white dwarf astrophysics. Parallel sessions touch on dark matter, neutrinos, X-ray sources, astrophysical black holes, neutron stars, white dwarfs, binary systems, radiative transfer, accretion disks, quasars, gamma ray bursts, supernovas, alternative gravitational theories, perturbations of collapsed objects, analog models, black hole thermodynamics, numerical relativity, gravitational lensing, large scale structure, observational cosmology, early universe models and cosmic microwave background anisotropies, inhomogeneous cosmology, inflation, global structure, singularities, chaos, Einstein-Maxwell systems, wormholes, exact solutions of Einstein's equations, gravitational waves, gravitational wave detectors and data analysis, precision gravitational measurements, quantum gravity and loop quantum gravity, quantum cosmology, strings and branes, self-gravitating systems, gamma ray astronomy, cosmic rays and the history of general relativity