2,246 research outputs found
Quantum Sensing Experiments with Superconducting Qubits
Quantum sensing is a vast and emerging field enabling in-situ studies of quantum systems and hence the development of quantum hybrid systems. This work creates the fundament of direct superconducting-magnetic hybrid systems by developing a local microwave sensing scheme and studying the influence of a static magnetic field on a superconducting qubit. Finally, a proof-of-principle hybrid system is demonstrated, which opens the path towards superconducting-magnetic quantum circuits
Multidimensional approximate Riemann solvers for hyperbolic systems
Esta tesis doctoral se centra en el desarrollo de resolvedores de Riemann multidimensionales incompletos eficientes para sistemas hiperbólicos generales, aplicables tanto en el caso conservativo como en el no conservativo. Dichos resolvedores se construyen a partir de un modelo de cuatro ondas, dadas por las velocidades de propagación maximales en cada vértice de una malla estructurada. En particular, se construye una versión simple de un esquema HLL 2D bien equilibrado, la cual se toma como base para diseñar una clase más general de resolvedores de Riemann incompletos 2D, los denominados esquemas AVM (Approximate Viscosity Matrix). La gran ventaja de los esquemas AVM es la posibilidad de controlar la cantidad de difusión numérica considerada para cada sistema hiperbólico, con un coste computacional razonable. Se demuestra que los esquemas numéricos de primer orden resultantes son consistentes con el sistema hiperbólico considerado, y linealmente estables bajo una condición CFL de hasta la unidad. Tales esquemas pueden ser usados como base para construir esquemas de alto orden. En esta tesis, se construye un esquema de segundo orden mediante el método predictor-corrector MUSCL-Hancock. Para analizar las propiedades de los esquemas propuestos, se han considerado experimentos numéricos en magnetohidrodinámica (MHD) y sistemas de aguas someras (SWE) de una y dos capas. En el caso de MHD, la condición de divergencia nula se ha impuesto mediante una nueva técnica basada en la escritura no conservativa de las ecuaciones. Por otro lado, para SWE, la presencia de la topografía del fondo y de los términos de acoplamiento entre capas representan una dificultad adicional, que se resuelve dentro del marco de los esquemas camino-conservativos. Por último, se ha desarrollado un algoritmo simple y eficiente para la implementación de los esquemas en tarjetas gráficas (GPU), con el objetivo de aumentar la eficiencia computacional
A cost estimation for CO2 reduction and reuse by methanation from cement industry sources in Switzerland
The Swiss government has signed the Paris Climate Agreement and various measures need to be implemented in order to reach the target of a 50% reduction in CO2 emissions in Switzerland by 2030 compared with the value for 1990. Considering the fact that the production of cement in Switzerland accounts around 2.5 million ton for CO2 emissions of which corresponds to roughly 7% of the country’s total CO2 emissions, the following article examines how this amount could be put to meaningful use in order to create a new value-added chain through CO2 methanation, and thus reduce the consumption and import of fossil fuels in Switzerland. With power-to-gas technology, this CO2, along with regenerative hydrogen from photovoltaics, can be converted into methane, which can then be fed into the existing natural-gas grid. This economic case study shows a cost prediction for conversion of all the CO2 from the cement industry into methane by using the technologies available today in order to replacing fossil methane imports
Transmon Qubit in a Magnetic Field: Evolution of Coherence and Transition Frequency
We report on spectroscopic and time-domain measurements on a fixed-frequency
concentric transmon qubit in an applied in-plane magnetic field to explore its
limits of magnetic field compatibility. We demonstrate quantum coherence of the
qubit up to field values of , even without an optimized
chip design or material combination of the qubit. The dephasing rate
is shown to be not affected by the magnetic field in a broad
range of the qubit transition frequency. For the evolution of the qubit
transition frequency, we find the unintended second junction created in the
shadow angle evaporation process to be non-negligible and deduce an analytic
formula for the field-dependent qubit energies. We discuss the relevant
field-dependent loss channels, which can not be distinguished by our
measurements, inviting further theoretical and experimental investigation.
Using well-known and well-studied standard components of the superconducting
quantum architecture, we are able to reach a field regime relevant for quantum
sensing and hybrid applications of magnetic spins and spin systems.Comment: 9 pages, 8 figure
Analog quantum simulation of the Rabi model in the ultra-strong coupling regime
The quantum Rabi model describes the fundamental mechanism of light-matter
interaction. It consists of a two-level atom or qubit coupled to a quantized
harmonic mode via a transversal interaction. In the weak coupling regime, it
reduces to the well-known Jaynes-Cummings model by applying a rotating wave
approximation (RWA). The RWA breaks down in the ultra-strong coupling (USC)
regime, where the effective coupling strength is comparable to the energy
of the bosonic mode, and remarkable features in the system dynamics
are revealed. We demonstrate an analog quantum simulation of an effective
quantum Rabi model in the USC regime, achieving a relative coupling ratio of
. The quantum hardware of the simulator is a superconducting
circuit embedded in a cQED setup. We observe fast and periodic quantum state
collapses and revivals of the initial qubit state, being the most distinct
signature of the synthesized model.Comment: 20 pages, 13 figure
Pyrite utilization in the carboniferous region of Santa Catarina, Brazil : potentials, challenges, and environmental advantages
The main coal seams explored in the coal region of Santa Catarina are Barro Branco (BB) and Bonito (BO). Owing to the association with the mineral matter, the tailings generated in the beneficiation are arranged in disposal areas, and subject to the generation of acid mine drainage (AMD). The objective of this study was to evaluate the use of pyrite present in the coal rejects of the BB and BO seams and the environmental gains with desulfurization. For this purpose, densimetric separability test, ash, sulfur, and AMD generation analyses were performed. In addition, the amount of pyritic concentrates and sulfuric acid were estimated considering the current level of production. Three densimetric fractions were obtained: less than 2.2 (energetic material), between 2.2 and 2.7 (low sulfur material), and greater than 2.7 g cm-3 (pyrite concentrate). The results revealed that the two seams could be beneficiated by gravimetric processes, obtaining pyrite concentrates with approximately 60% pyrite. By converting pyrite to sulfuric acid would represent an increase of 500,000 tons per year in the Brazilian production of this material and, in environmental terms, a reduction of up to 90% of the acidity potential to be disposed in the environment in the case of the BB seam and 65% for the BO seam. It was also observed that the “desulfurized” fraction of the BO had higher levels of pyrite and a higher potential for acidity generation than the BB seam, implying greater risks of environmental contamination and higher acid water treatment costs
Multi-mobile robot and avoidance obstacle to spatial mapping in indoor environment
The advancement of technology and techniques applied to robotics contributes to increasing the quality of life
and safety of humanity. One of the most widespread applications of mobile robotics is related to monitoring
indoor environments. However, due to factors such as the size of the environment impacting the monitoring
response, battery autonomy, and autonomous navigation in environments with unknown obstacles, they are
still significant challenges in the diffusion of mobile robotics in these areas. Strategy adopting multiple robots
can overcome these challenges. This work presents an approach to use multi-robots in hazardous environments
with gas leakage to perform spatial mapping of the gas concentration. Obstacles arranged in the environment
are unknown to robots, then a fuzzy control approach is used to avoid the collision. As a result of this paper,
spatial mapping of an indoor environment was carried out with multi-robots that reactively react to unknown
obstacles considering a point gas leak with Gaussian dispersion.This work has been supported by FCT - Fundação para a Ciência e Tecnologia within the Project Scope:
UIDB/05757/2020. Additionally, this work was supported in part by the National Counsel of Technological
and Scientific Development of Brazil (CNPq), in part by the Coordination for the Improvement of
Higher Level People (CAPES).info:eu-repo/semantics/publishedVersio
Fault-tolerance in cyber-physical systems: literature review and challenges
Modern industry demands techniques that ensure
the operability of its processes, and even though the exponential
technological advance in the last two decades in the manufacturing
field, failures, waste, and unexpected interruptions are still
present in this sector’s daily routine. Within the Industry 4.0
context, fault-tolerant (FT) production systems remain a complex
issue and sometimes represent a vulnerable aspect. Faulttolerance
techniques dedicated to autonomous and distributed
systems, in a cyber-physical system (CPS) perspective, need to be
investigated to follow the evolutionary pace of the manufacturing
scenarios. This paper overviews these concepts and analyses the
current situation in developing FT for CPS systems through a
systematic literature review. The paper also discusses the research
challenges in this new kind of FT systems due to new distributed
architectures and emerging technologies, matching the several
fault-tolerance phases.This work has been supported by FCT - Fundação
para a Ciência e Tecnologia within the Project Scope:
UIDB/05757/2020. This work has been partially supported by
the European Regional Development Fund (ERDF) through
the Interreg Spain-Portugal V-A Program (POCTEP) under
grant 0677 DISRUPTIVE 2 E (Intensifying the activity of
Digital Innovation Hubs within the PocTep region to boost the
development of disruptive and last generation ICTs through
cross-border cooperation).info:eu-repo/semantics/publishedVersio
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