Artificial Intelligence for Science in Quantum, Atomistic, and Continuum Systems

Advances in artificial intelligence (AI) are fueling a new paradigm of discoveries in natural sciences. Today, AI has started to advance natural sciences by improving, accelerating, and enabling our understanding of natural phenomena at a wide range of spatial and temporal scales, giving rise to a new area of research known as AI for science (AI4Science). Being an emerging research paradigm, AI4Science is unique in that it is an enormous and highly interdisciplinary area. Thus, a unified and technical treatment of this field is needed yet challenging. This work aims to provide a technically thorough account of a subarea of AI4Science; namely, AI for quantum, atomistic, and continuum systems. These areas aim at understanding the physical world from the subatomic (wavefunctions and electron density), atomic (molecules, proteins, materials, and interactions), to macro (fluids, climate, and subsurface) scales and form an important subarea of AI4Science. A unique advantage of focusing on these areas is that they largely share a common set of challenges, thereby allowing a unified and foundational treatment. A key common challenge is how to capture physics first principles, especially symmetries, in natural systems by deep learning methods. We provide an in-depth yet intuitive account of techniques to achieve equivariance to symmetry transformations. We also discuss other common technical challenges, including explainability, out-of-distribution generalization, knowledge transfer with foundation and large language models, and uncertainty quantification. To facilitate learning and education, we provide categorized lists of resources that we found to be useful. We strive to be thorough and unified and hope this initial effort may trigger more community interests and efforts to further advance AI4Science

Auditory group theory with applications to statistical basis methods for structured audio

Thesis (Ph. D.)--Massachusetts Institute of Technology, Program in Media Arts & Sciences, 1998.Includes bibliographical references (p. 161-172).Michael Anthony Casey.Ph.D

Progressive design and self-assembly of supramolecular architectures : based on metallamacrocyclic nickel(II) complexes with bipodal tetra-alkylaroylbis (thioureas)

Includes bibliographical references.Rationally designed bipodal3,3,3',3'-tetraalkyl-l,1'-benzoylbis(thioureas) are used as pre-programmed cheiating ligands to form metallamacrocyclic square planar nickel(ll) complexes via self-assembly. Metal : ligand stoichiometries of either 2:2 or 3:3 can be achieved by using meta- or para- substituted ligands. The metallamacrocyclic complexes are subsequently converted into octahedral adducts via the addition of monodentate nitrogen donor ligands. Metallamacrocycles are further employed as secondary building units in the self-assembly of I-dimensional double- or tripleconnected coordination polymers. The synthesis of these polymers is achieved with the use of exo-bidentate nitrogen donor ligands

Multinuclear Solid-State NMR Investigation of Structure, Dynamics, and Formation of Porous Materials

The work described herein demonstrates the utility of solid-state nuclear magnetic resonance (SSNMR) spectroscopy for the characterization of molecular-level structure and dynamics in porous materials, including the determination of the reaction pathways involved in the formation of porous solids made via solid-state synthetic techniques, a study of the motion of dynamic components of metal-organic frameworks (MOFs) that are prototypes for future molecular machines, and the structural characterization of a surface-supported catalyst. In Chapters 2 and 3, accelerated aging and mechanochemical reactions are used to synthesize cadmium-containing zeolitic imidazolate frameworks (ZIFs). These techniques provide a means for clean and efficient syntheses of these materials; however, little is known about the reaction kinetics and mechanisms underlying their production. First, the structure of a new cadmium-imidazolate framework (CdIF) is determined using a combination of powder X-ray diffraction (PXRD) and SSNMR, a methodology known as NMR-assisted crystallography. SSNMR experiments are also used to monitor the formation of ZIFs made using mechanochemical synthesis, providing information on the intermediates and products of the reactions. It is revealed that the initial mechanochemical ball milling provides the activation energy for the formation of ZIFs, but aging reactions within the milling jars drive the reaction to completion. As demonstrated here, milling times as short as five seconds provide enough energy for the initiation of the reactions, allowing for extremely low-energy synthesis of these materials. In Chapter 4, series of metal-organic frameworks (MOFs) with dynamic, interlocked crown ether rings are investigated to determine the factors that influence the motion of the rings. It is demonstrated that the size of the rings and the framework structure affect the motion. 13C variable temperature SSNMR is used to confirm the shuttling motion of rings between recognition sites on an axle that is incorporated into a MOF. Next, a study on a series of simple inorganic molecular rotors is described. It is shown that some of these compounds act as rotors with very low energy barriers that exhibit random rotational dynamics at temperatures below 75 K, while other structurally similar compounds do not display any motions over a wide range of temperatures. It is posited that steric and electronic effects from the coordinating ligands are responsible for the observed dynamics. 2H SSNMR is shown to be essential for classifying and understanding the dynamics of these low-energy molecular rotors Finally, 35Cl SSNMR is used to elucidate the structure of a transition-metal compound bound to the surface of a porous silica material. It is demonstrated that ultra-wideline (UW) 35Cl SSNMR spectra for transition-metal complexes can be rapidly acquired using a combination of high magnetic fields and specialized pulse sequences. These spectra allow for the differentiation of different Cl bonding environments (i.e., bridging, terminal axial, and terminal equatorial). Density functional theory (DFT) calculations and an accompany molecular-orbital analysis allow for an understanding of the origin of the observed 35Cl electric field gradient (EFG) parameters, which influence the 35Cl quadrupolar interactions. The structure of a surface-supported complex is then proposed, demonstrating the applicability of these techniques to the study of very dilute catalytic species

Hardware-accelerated algorithms in visual computing

This thesis presents new parallel algorithms which accelerate computer vision methods by the use of graphics processors (GPUs) and evaluates them with respect to their speed, scalability, and the quality of their results. It covers the fields of homogeneous and anisotropic diffusion processes, diffusion image inpainting, optic flow, and halftoning. In this turn, it compares different solvers for homogeneous diffusion and presents a novel \u27extended\u27 box filter. Moreover, it suggests to use the fast explicit diffusion scheme (FED) as an efficient and flexible solver for nonlinear and in particular for anisotropic parabolic diffusion problems on graphics hardware. For elliptic diffusion-like processes, it recommends to use cascadic FED or Fast Jacobi schemes. The presented optic flow algorithm represents one of the fastest yet very accurate techniques. Finally, it presents a novel halftoning scheme which yields state-of-the-art results for many applications in image processing and computer graphics.Diese Arbeit präsentiert neue parallele Algorithmen zur Beschleunigung von Methoden in der Bildinformatik mittels Grafikprozessoren (GPUs), und evaluiert diese im Hinblick auf Geschwindigkeit, Skalierungsverhalten, und Qualität der Resultate. Sie behandelt dabei die Gebiete der homogenen und anisotropen Diffusionsprozesse, Inpainting (Bildvervollständigung) mittels Diffusion, die Bestimmung des optischen Flusses, sowie Halbtonverfahren. Dabei werden verschiedene Löser für homogene Diffusion verglichen und ein neuer \u27erweiterter\u27 Mittelwertfilter präsentiert. Ferner wird vorgeschlagen, das schnelle explizite Diffusionsschema (FED) als effizienten und flexiblen Löser für parabolische nichtlineare und speziell anisotrope Diffusionsprozesse auf Grafikprozessoren einzusetzen. Für elliptische diffusionsartige Prozesse wird hingegen empfohlen, kaskadierte FED- oder schnelle Jacobi-Verfahren einzusetzen. Der vorgestellte Algorithmus zur Berechnung des optischen Flusses stellt eines der schnellsten und dennoch äußerst genauen Verfahren dar. Schließlich wird ein neues Halbtonverfahren präsentiert, das in vielen Bereichen der Bildverarbeitung und Computergrafik Ergebnisse produziert, die den Stand der Technik repräsentieren

Application of polarized Raman spectroscopy for analysis of phase transitions and anisotropic behavior of soft condensed matter

The importance of soft matter research, as a major class of materials including liquid crystals, polymers, colloids, emulsions, and forms, is attributed to the behavior resemblances in each branch of soft matter responding to the external perturbations. Hence, one of the most required inquiries in soft matter physics is understanding how the structures with characteristic length scales evolve in response to external perturbations, and concomitant phase transitions. We have focused on adopting polarized Raman spectroscopy to probe phase transitions in soft materials consisting of anisometric components and the evolution of molecular orientational ordering as a complementary tool to other methodologies, but distinct in some respects. The primary task is quantifying the degree of molecular orientation, i.e., obtaining orientational order parameters, in liquid crystal (LCs) system. Thermal evolution of orientation degree in a hitherto elusive biaxial nematic (Nb) phase as well as a commonly known uniaxial nematic (Nu) phase were interrogated from the measurements of anisotropy in polarized Raman intensities. We demonstrated reliable and applicable method to quantify the orientation degree for systems possessing anisotropic ordering. We also addressed a strong potential of Raman spectroscopy that the changes of vibrational energy reflect the variations of intermolecular interactions and structural changes on the molecular level induced by phase transitions. As a subfield of soft matter, we characterized phase transitions and anisotropic ordering observed in an evaporating conjugated polymer solution and elucidated the mechanism of the entities undergoing phase transitions using mainly polarized Raman spectroscopy. In addition, we have shown that tracking Raman spectral changes can provide valuable information for understanding structure-property relations when the measurements of the evolution in physical properties are carried out simultaneously.PhDCommittee Chair: Srinivasarao, Mohan; Committee Member: El-Sayed, Mostafa; Committee Member: Fernandez, Alberto; Committee Member: Griffin, Anselm; Committee Member: Park, Jung Ok; Committee Member: Reichmanis, Elsa; Committee Member: Rey, Alejandro; Committee Member: Tolbert, Lare

Publications of the Jet Propulsion Laboratory 1976

The formalized technical reporting, released January through December 1975, that resulted from scientific and engineering work performed, or managed, by the Jet Propulsion Laboratory is described and indexed. The following classes of publications are included: (1) technical reports; (2) technical memorandums; (3) articles from bi-monthly Deep Space Network (DSN) progress report; (4) special publications; and (5) articles published in the open literature. The publications are indexed by: (1) author, (2) subject, and (3) publication type and number. A descriptive entry appears under the name of each author of each publication; an abstract is included with the entry for the primary (first-listed) author. Unless designated otherwise, all publications listed are unclassified