188 research outputs found
Beam scanning by liquid-crystal biasing in a modified SIW structure
A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium
Fictional Practices of Spirituality I: Interactive Media
"Fictional Practices of Spirituality" provides critical insight into the implementation of belief, mysticism, religion, and spirituality into worlds of fiction, be it interactive or non-interactive. This first volume focuses on interactive, virtual worlds - may that be the digital realms of video games and VR applications or the imaginary spaces of life action role-playing and soul-searching practices. It features analyses of spirituality as gameplay facilitator, sacred spaces and architecture in video game geography, religion in video games and spiritual acts and their dramaturgic function in video games, tabletop, or LARP, among other topics. The contributors offer a first-time ever comprehensive overview of play-rites as spiritual incentives and playful spirituality in various medial incarnations
Electronic Structure Methods for Large Molecular Systems and Materials in Strong Magnetic Fields
The high-rank polynomial scaling of modern electronic structure methods can present significant limitations on the size of molecular systems that can be accurately studied. This issue is further exasperated when using non-perturbative approaches for studying systems within arbitrary strength magnetic fields due to the requirements for complex algebra and reduced permutational symmetry. One such attempt at overcoming this issue is the concept of fragmentation, which has shown promise in recent years for accurately determining the electronic structure of systems that can be sensibly fragmented into smaller subunits. The main aim in this work is to combine the concepts of one such method, the embedding fragment method (EFM), with recent advances in non-perturbative treatment of external fields, enabling the study of increasingly large or complex systems. The implementation of this approach is presented for systems in strong magnetic fields. The method is applied to determine energetic, structural and magnetic response properties of systems beyond the scope of more conventional methods. The EFM is shown to provide an accurate electronic structure approximation when studying systems within extremely strong magnetic fields, with errors generally 70000 Tesla. Its application to large water clusters is presented showing how external magnetic fields strengthen intermolecular interactions, as has previously been demonstrated through experiment, but that the origin of this strengthening is not as straightforward as the altering of the hydrogen bonding present at zero field, a rational often considered alongside experimental results. Also demonstrated is how this approach can be used to accurately model solvation effects when calculating magnetic properties of solute molecules. In this work the calculation of nuclear magnetic resonance chemical shifts is considered, using the EFM and comparing to both gas phase calculations and calculations including solvent effects using the polarisable continuum method. To aid in the interpretation of results, two additional tool sets have been development. The first is a suite of tools to analyse the complex current vector field induced by exposing a molecule to an external field. The second is a new molecular viewer software package, improving the ability to analyse the effects of external magnetic fields on molecular systems
Development and application of ab initio electron dynamics on traditional and quantum compute architectures
Electron dynamics processes are of utmost importance in chemistry. For example, light-induced processes are used in the field of photocatalysis to generate a wide variety of products by charge transfer, bond breaking, or electron solvation. Also in the field of materials science, more and more such processes are known and utilized, for example, to design more efficient solar cells. Even the formation of bonds in molecules is an electron dynamics process. Through experimental progress, it is now even possible to trigger specific processes and chemical reactions with special laser pulses.
To study all these processes, computer-aided simulations are an indispensable tool. Depending on the size of the molecules considered and the desired accuracy, however, the underlying quantum-mechanical properties result in numerical formulas whose computation far exceeds the capabilities of even modern supercomputers.
In this thesis, three projects are presented to demonstrate modern use cases of electron dynamics and show how recent developments in computer technology and software design can be used to develop more efficient and user-friendly programs.
In the first project, the inter-Coulombic decay (ICD), an ultrafast energy transfer process, between two isolated chemical structures is investigated. After the excitation of one structure, the energy is transferred to the other, which is ionized as a result. The process has already been shown experimentally in atoms and molecules and is studied here for quantum dots, focusing on systems with more quantum dots and higher dimensions for the continuum than in previous studies. These elaborate studies are made possible by implementing computationally intensive program parts of the Heidelberg MCTDH program used on graphics processing units (GPUs). The performed studies show how the ICD process behaves with multiple partners as well as which competing decay processes occur and thus provide relevant information for the development of technologies based on quantum dots such as quantum dot qubits for use in quantum computers.
Electron dynamics processes are not only relevant in the development of new quantum computers, but conversely, quantum computers can also provide the ability to perform electron dynamics with significantly more interacting electrons and a smaller error than it would ever be possible with traditional computers. In another project, therefore, a quantum algorithm was developed that could enable such simulations and their analysis in the future.
The quantum algorithm was implemented in the dynamics program Jellyfish, which was also developed in the context of this dissertation. The program is based on a graphical user interface oriented on dataflow programming, which simultaneously leads to a modular structure. The resulting modules can be combined flexibly, which allows Jellyfish to be used for a wide variety of applications. In addition to dynamic algorithms, novel analysis methods were developed and demonstrated on laser-driven electronic excitations in molecules such as hydrogen, lithium cyanide, or guanine. Thus, the generation of electronic wave packets as well as transitions between electronic states were studied in an explicitly time-dependent manner and the formation of the exciton in such processes was described qualitatively by means of densities as well as quantitatively by so-called exciton descriptors such as exciton size or hole and particle position.
Thus, in summary, this dissertation presents both new insights into electron dynamic processes and new possibilities for more efficient simulation of these processes using GPU implementations and quantum algorithms. The developed dynamics program Jellyfish offers the potential to be used in many further studies in this area and to be extended to allow for example simulations with a continuum like in the ICD calculations in the future
1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface
A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance
Governance, power and resilience in planning for urban density in Mumbai
This research investigates three intersecting policy arenas relating to urban density to gain insights into urban governance in Mumbai. The policy arenas each comprise debates prominently framed around urban density: the 2014-2034 Development Plan for Greater Mumbai (high-density nodes); the Eastern Waterfront redevelopment project (decongesting Mumbai); and Slum Redevelopment and Rehabilitation policies (overcrowding). Specifically, the research investigates how stakeholders engage in - and seek to influence – each of these policy arenas, and what implication that has for their own resilience and that of the city as a social-ecological urban system (SEuS).
Engaging with literatures on social-ecological resilience and urban governance, this research adopts a ‘governance for resilience’ frame to explore how actors and knowledges come together to debate and shape policy outcomes, and what practices emerge to shape the governance landscape. The empirical data gives evidence to the idea that planning for urban density in Mumbai is neither a benign nor rational policy manoeuvre, but it polarises stakeholders and places emphasis on divisions between opposing interests, public, private and civic. Investigating the way in which urban density is framed and debated within policy arenas sheds light on the ways in which urban density is politicized and governed by mediations, contestations, tactics, and evolutions within the panarchy of governance. Elaborating these reveals the polarisations in the governance landscapes around urban density in Mumbai and informs how power plays out in governing for resilience. The research reveals that fragmentations in formal governance are overcome by experimentation and innovation at the grassroots. It argues that, even when remembrance (top-down inertia) dominates, active revolt (bottom-up self-organisation, experimentation, and protest) plays a role in building the resources for resilience. Lastly, it shows how - through the actions of international players, internationally dominant discourses, political influences and the power of the State (remembrance) - the city itself is rendered powerless to govern its future. Thus, this research identifies characteristics of governance that support (or hinder) resilience at multiple scales, providing an indication of what 'governance for resilience' may look like. In addition, it provides a perspective on how planners and political scientists might understand and engage with resilience, for the mutual benefit of both areas of scholarship
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
Rethinking extractive landscapes in cross-border areas
peer reviewedWith the gradual cessation of the extractive industry in Western Europe, the 1990s saw the emergence of an awareness of the spatial and cultural values of abandoned mines and quarries. In the wake of the 'industrial heritage tourism', the 'mining tourism' arose, converting derelict extractive facilities into touristic and recreational attractions. In their attempt at economic regeneration, recycling projects for disused extractive plants have often neglected their relationship with landscape, comprising ecosystems and cultural networks pre-existing, contemporary and successive to mining and quarrying time. Adopting an architectural approach, the research explores the manufactured landscape resulting from the exploitation of underground resources, highlighting the spatial, cultural and ecological continuity between underground, sub-surface and surface. Hence, the 'extractive landscape' emerges as a constantly evolving manifestation of human-nature interactions
Review of Particle Physics
The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,143
new measurements from 709 papers, we list, evaluate, and average measured properties of gauge bosons and the
recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical
particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search
limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs
Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology,
Particle Detectors, Colliders, Probability and Statistics. Among the 120 reviews are many that are new or heavily
revised, including a new review on Machine Learning, and one on Spectroscopy of Light Meson Resonances.
The Review is divided into two volumes. Volume 1 includes the Summary Tables and 97 review articles. Volume
2 consists of the Particle Listings and contains also 23 reviews that address specific aspects of the data presented
in the Listings.
The complete Review (both volumes) is published online on the website of the Particle Data Group (pdg.lbl.gov)
and in a journal. Volume 1 is available in print as the PDG Book. A Particle Physics Booklet with the Summary
Tables and essential tables, figures, and equations from selected review articles is available in print, as a web version
optimized for use on phones, and as an Android app.United States Department of Energy (DOE) DE-AC02-05CH11231government of Japan (Ministry of Education, Culture, Sports, Science and Technology)Istituto Nazionale di Fisica Nucleare (INFN)Physical Society of Japan (JPS)European Laboratory for Particle Physics (CERN)United States Department of Energy (DOE
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