29,260 research outputs found
RESOURCE ALLOCATION FOR EMERGING APPLICATIONS IN RIS-ENABLED 6G AND BEYOND NETWORKS
No full textReconfigurable intelligent surfaces (RISs) have emerged as a promising technology capable of enhancing the performance of wireless networks by smartly reconfiguring the wireless propagation environment using low-cost reflective elements integrated on planar surfaces. The controllable signal reflections from RISs are highly beneficial for coverage extension and seamless connectivity, especially in complex urban environments, where signal propagation may often be blocked by high-rise buildings and a large number of city infrastructure. In this context, this thesis investigates potential and practical scenarios of RIS-assisted networks in complex urban propagation environments, e.g., smart cities, and the relevant network optimization objectives. In addition, the study presents innovative algorithms, emerging applications, and deployment strategies for RIS-assisted 6G and beyond wireless networks. Thus, contributing to the advancement of RIS-based beamforming and resource allocation for future wireless networks.
Firstly, we investigate user admission maximization in a challenging RIS-aided smart city street scenario. We jointly optimize multislot scheduling, precoding, and RIS-based beamforming to maximize user admission under quality of service (QoS) and base station (BS) power constraints. To solve the resulting problem with affordable complexity, an efficient iterative algorithm that incorporates binary variable relaxation, alternating optimization (AO), and successive convex approximation (SCA) is proposed. Secondly, a significant contribution of this work lies in investigating typical scenarios in complex propagation environments where multiple RISs are deployed in different hotspot areas to overcome blockages between the BS and users. A robust resource allocation design to ensure fair service access to users in different hotspot areas supported by distributed RISs is proposed. Specifically, we maximize the minimum number of served users in proximity to each RIS subject to the available BS power and worst-case QoS constraints. To solve the challenging problem, we leverage tools from binary variable relaxation, mathematical transformations, convex approximation techniques, and the AO algorithm. Additionally, we handle the semi-infinite uncertainty constraints by employing the S-procedure and general sign-definiteness. Thirdly, we investigate a communication-centric RIS-enhanced orthogonal frequency division multiplexing (OFDM) multiple-input multiple-output (MIMO) integrated sensing and communication (ISAC) system, where a RIS is deployed to assist communication users in a localized coverage gap. The objective is to optimize the trade-off between communication and sensing while ensuring energy efficiency. We formulate and study two performance metrics: i) maximize the system's sum spectral efficiency and ii) maximize the global energy efficiency subject to the available BS power, RIS phase shift design, sensing subcarrier allocation, and accuracy constraints. To tackle this, we develop efficient iterative algorithms leveraging successive convex approximation, alternating optimization, Riemannian manifolds, and Dinkelbach’s method to obtain at least locally optimal solutions.
Finally, we summarize the key conclusions of the thesis and suggest potential directions for future research.U-AGR-7046 - C20/IS/14773976/RISOTTI - OTTERSTEN Björ
Efficient implementation of the domain-integrated field relations method for quasi-static magnetic fields
No full textAuthor accepted manuscript of the 17th Annual Review of Progress in Applied Computational Electromagnetics, Monterey, pp. 337-344, 19 Mar 2001 → 23 Mar 2001Electrical Engineering, Mathematics and Computer Scienc
Endocarditis and ascending aortic aneurysm with aortic valve insufficiency secondary to late syphilis: Case report
No full textVenereal syphilis, caused by Treponema pallidum, is a major global health problem. Untreated latent syphilis can progress to tertiary syphilis, often leading to severe complications such as cardiac involvement, particularly syphilitic aortitis, which may manifest decades after the initial infection. We present a case of a 46-year-old woman who developed an ascending aortic aneurysm and severe aortic valve insufficiency due to late-stage syphilis. She presented with bilateral lower limb edema, intermittent chest pain, decreased functional capacity, and dyspnea, ultimately requiring hospitalization for cardiogenic shock. Diagnostic imaging revealed significant aortic valve damage and aneurysmal dilation of the ascending aorta, while serological tests confirmed tertiary cardiovascular syphilis. Surgical intervention involved the reconstruction of the ascending aorta and replacement of the aortic valve with a bioprosthetic valve. Histopathological analysis indicated chronic endocarditis. Postoperative management included intensive care support and antibiotic treatment. The patient demonstrated satisfactory recovery, with no further complications reported at the 3-month follow-up. © The Author(s) 2024
Competition through Technical Progress
No full textThe relationship between technical progress and price competition is a controversial issue in economics. This paper highlights the fact that investment in technical progress is an authentic type of competition which benefits the consumers rather than the industry. This type of competition exists when the potential for technical progress, which can be incorporated by firms through investment, is high enough. Competition is, in fact, made up of two components: A static one which is known as price or quantity competition and a dynamic one, the Technical Progress competition which also contribute to reduce prices and increase quantities for consumers. Consequently, the economic factors that increase a firm's margin do not have to be viewed as the consumers' enemy, but rather as an ally, under specific conditions, because they allow higher investments in new technology by which firms increase their capacities and attract higher demand from consumers. This paper also underlines that, for a mature market, the maximum Consumer Surplus as well as Social Welfare are attained by a constant level of combined competition which is only dependent on the size of the market and the number of firms. The level of combined competition can be defined as the product of the static and the dynamic level of competition. As a consequence, the higher the potential of technical progress is, the lower the level of static competition must be in order to reach the maximum level of Consumer Surplus and Social Welfare. --Investment,Competition,Technical Progress,Dynamic Competition
Philosophy doesn't need a concept of progress
No full textPhilosophical progress is one of the most controversial topics in metaphilosophy. It has been widely debated whether philosophy makes any progress in history. This paper revisits the concept of philosophical progress. It first identifies two criteria of an ideal concept of philosophical progress. It then argues that our accounts of philosophical progress fail to provide such an ideal concept. Finally, it argues that not only do we not have a good concept of philosophical progress, we also do not need a concept of philosophical progress in order to arrive at a good understanding of the history of philosophy
Oregon's survey data
No full textThis archived document is maintained by the Oregon State Library as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Title from PDF caption (viewed on Octover 30, 2014)Converted from a Word documentExplores the Hispanic and non-Hispanic differences in the Oregon Population Survey and Hispanic population demographics from the three-year American Communities Survey dataset (2005-2007)Mode of access: Internet from the Oregon Government Publications Collection.Text in Englis
Progress in Economics
No full textThe Author discusses the relevance of studying the progress made in economic research and how to assess the existence of different models
Automating Proof Steps of Progress Proofs: Comparing Vampire and Dafny
No full textDeveloping provably sound type systems is a non-trivial task which, as of today, typically requires expert skills in formal methods and a considerable amount of time. Our Veritas [3] project aims at providing support for the development of soundness proofs of type systems and efficient type checker implementations from type system specifications. To this end, we investigate how to best automate typical steps within type soundness proofs. In this paper, we focus on progress proofs for type systems of domain-specific languages. As a running example for such a type system, we model a subset SQL and augment it witha type system. We compare two different approaches for automating proof steps of the progress proofs for this type system against each other: firstly, our own tool Veritas, which translates proof goals and specifications automatically to TPTP [13] and calls Vampire [8] on them, and secondly, the programming language Dafny [6], which translates proof goals and specifications to the intermediate verification language Boogie 2 [5] and calls the SMT solver Z3 [9] on them. We find that Vampire and Dafny are equally well-suited for automatically proving simple steps within progress proofs.Accepted Author ManuscriptProgramming Language
A review of dynamical resonances in A plus BC chemical reactions
No full textThe concept of the transition state has played an important role in the field of chemical kinetics and reaction dynamics. Reactive resonances in the transition-state region can dramatically enhance the reaction probability; thus investigation of the reactive resonances has attracted great attention from chemical physicists for many decades. In this review, we mainly focus on the recent progress made in probing the elusive resonance phenomenon in the simple A + BC reaction and understanding its nature, especially in the benchmark F/Cl + H-2 and their isotopic variants. The signatures of reactive resonances in the integral cross section, differential cross section (DCS), forward-and backward-scattered DCS, and anion photodetachment spectroscopy are comprehensively presented in individual prototype reactions. The dynamical origins of reactive resonances are also discussed in this review, based on information on the wave function in the transition-state region obtained by time-dependent quantum wave-packet calculations
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