5,137 research outputs found

    UMSL Bulletin 2023-2024

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    The 2023-2024 Bulletin and Course Catalog for the University of Missouri St. Louis.https://irl.umsl.edu/bulletin/1088/thumbnail.jp

    The AddACO: A bio-inspired modified version of the ant colony optimization algorithm to solve travel salesman problems

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    The Travel Salesman Problem (TSP) consists in finding the minimal-length closed tour that connects the entire group of nodes of a given graph. We propose to solve such a combinatorial optimization problem with the AddACO algorithm: it is a version of the Ant Colony Optimization method that is characterized by a modified probabilistic law at the basis of the exploratory movement of the artificial insects. In particular, the ant decisional rule is here set to amount in a linear convex combination of competing behavioral stimuli and has therefore an additive form (hence the name of our algorithm), rather than the canonical multiplicative one. The AddACO intends to address two conceptual shortcomings that characterize classical ACO methods: (i) the population of artificial insects is in principle allowed to simultaneously minimize/maximize all migratory guidance cues (which is in implausible from a biological/ecological point of view) and (ii) a given edge of the graph has a null probability to be explored if at least one of the movement trait is therein equal to zero, i.e., regardless the intensity of the others (this in principle reduces the exploratory potential of the ant colony). Three possible variants of our method are then specified: the AddACO-V1, which includes pheromone trail and visibility as insect decisional variables, and the AddACO-V2 and the AddACO-V3, which in turn add random effects and inertia, respectively, to the two classical migratory stimuli. The three versions of our algorithm are tested on benchmark middle-scale TPS instances, in order to assess their performance and to find their optimal parameter setting. The best performing variant is finally applied to large-scale TSPs, compared to the naive Ant-Cycle Ant System, proposed by Dorigo and colleagues, and evaluated in terms of quality of the solutions, computational time, and convergence speed. The aim is in fact to show that the proposed transition probability, as long as its conceptual advantages, is competitive from a performance perspective, i.e., if it does not reduce the exploratory capacity of the ant population w.r.t. the canonical one (at least in the case of selected TSPs). A theoretical study of the asymptotic behavior of the AddACO is given in the appendix of the work, whose conclusive section contains some hints for further improvements of our algorithm, also in the perspective of its application to other optimization problems

    Orvosképzés 2023

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    Modeling and Simulation in Engineering

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    The Special Issue Modeling and Simulation in Engineering, belonging to the section Engineering Mathematics of the Journal Mathematics, publishes original research papers dealing with advanced simulation and modeling techniques. The present book, “Modeling and Simulation in Engineering I, 2022”, contains 14 papers accepted after peer review by recognized specialists in the field. The papers address different topics occurring in engineering, such as ferrofluid transport in magnetic fields, non-fractal signal analysis, fractional derivatives, applications of swarm algorithms and evolutionary algorithms (genetic algorithms), inverse methods for inverse problems, numerical analysis of heat and mass transfer, numerical solutions for fractional differential equations, Kriging modelling, theory of the modelling methodology, and artificial neural networks for fault diagnosis in electric circuits. It is hoped that the papers selected for this issue will attract a significant audience in the scientific community and will further stimulate research involving modelling and simulation in mathematical physics and in engineering

    2023-2024 academic bulletin & course catalog

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    University of South Carolina Aiken publishes a catalog with information about the university, student life, undergraduate and graduate academic programs, and faculty and staff listings

    Modelling, Dimensioning and Optimization of 5G Communication Networks, Resources and Services

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    This reprint aims to collect state-of-the-art research contributions that address challenges in the emerging 5G networks design, dimensioning and optimization. Designing, dimensioning and optimization of communication networks resources and services have been an inseparable part of telecom network development. The latter must convey a large volume of traffic, providing service to traffic streams with highly differentiated requirements in terms of bit-rate and service time, required quality of service and quality of experience parameters. Such a communication infrastructure presents many important challenges, such as the study of necessary multi-layer cooperation, new protocols, performance evaluation of different network parts, low layer network design, network management and security issues, and new technologies in general, which will be discussed in this book

    Current Insights on Lipid-Based Nanosystems

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    Lipid-based nanosystems, including solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), cationic lipid nanoparticles, nanoemulsions, and liposomes, have been extensively studied to improve drug delivery through different administration routes. The main advantages of these systems are their ability to protect, transport, and control the release of lipophilic and hydrophilic molecules (either small-molecular-weight molecules or macromolecules); the use of generally recognized as safe (GRAS) excipients that minimize the toxicity of the formulations; and the possibility to modulate pharmacokinetics and enable the site-specific delivery of encapsulated payloads. In addition, the versatility of lipid-based nanosystems has further been demonstrated for the delivery of vaccines, the protection of active cosmetic ingredients, and the improvement of moisturizing properties of cosmetic formulations.Lipid-based nanosystems are well established and there are already different commercially approved formulations for various human disorders. This success has paved the way for the diversification of the pipeline of development, to address unmet medical needs for several indications, such as cancer, neurological disorders, and autoimmune, genetic, and infectious diseases.This Special Issue aims to update readers on the latest research on lipid-based nanosystems, both at the preclinical and clinical levels. A series of 15 articles (six reviews and nine studies) is presented, with authors from 12 different countries, showing the globality of the investigations that are being carried out in this area

    High-order renormalization of scalar quantum fields

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    Thema dieser Dissertation ist die Renormierung von perturbativer skalarer Quantenfeldtheorie bei großer Schleifenzahl. Der Hauptteil der Arbeit ist dem Einfluss von Renormierungsbedingungen auf renormierte Greenfunktionen gewidmet. Zunächst studieren wir Dyson-Schwinger-Gleichungen und die Renormierungsgruppe, inklusive der Gegenterme in dimensionaler Regularisierung. Anhand zahlreicher Beispiele illustrieren wir die verschiedenen Größen. Alsdann diskutieren wir, welche Freiheitsgrade ein Renormierungsschema hat und wie diese mit den Gegentermen und den renormierten Greenfunktionen zusammenhängen. Für ungekoppelte Dyson-Schwinger-Gleichungen stellen wir fest, dass alle Renormierungsschemata bis auf eine Verschiebung des Renormierungspunktes äquivalent sind. Die Verschiebung zwischen kinematischer Renormierung und Minimaler Subtraktion ist eine Funktion der Kopplung und des Regularisierungsparameters. Wir leiten eine neuartige Formel für den Fall einer linearen Dyson-Schwinger Gleichung vom Propagatortyp her, um die Verschiebung direkt aus der Mellintransformation des Integrationskerns zu berechnen. Schließlich berechnen wir obige Verschiebung störungstheoretisch für drei beispielhafte nichtlineare Dyson-Schwinger-Gleichungen und untersuchen das asymptotische Verhalten der Reihenkoeffizienten. Ein zweites Thema der vorliegenden Arbeit sind Diffeomorphismen der Feldvariable in einer Quantenfeldtheorie. Wir präsentieren eine Störungstheorie des Diffeomorphismusfeldes im Impulsraum und verifizieren, dass der Diffeomorphismus keinen Einfluss auf messbare Größen hat. Weiterhin untersuchen wir die Divergenzen des Diffeomorphismusfeldes und stellen fest, dass die Divergenzen Wardidentitäten erfüllen, die die Abwesenheit dieser Terme von der S-Matrix ausdrücken. Trotz der Wardidentitäten bleiben unendlich viele Divergenzen unbestimmt. Den Abschluss bildet ein Kommentar über die numerische Quadratur von Periodenintegralen.This thesis concerns the renormalization of perturbative quantum field theory. More precisely, we examine scalar quantum fields at high loop order. The bulk of the thesis is devoted to the influence of renormalization conditions on the renormalized Green functions. Firstly, we perform a detailed review of Dyson-Schwinger equations and the renormalization group, including the counterterms in dimensional regularization. Using numerous examples, we illustrate how the various quantities are computable in a concrete case and which relations they satisfy. Secondly, we discuss which degrees of freedom are present in a renormalization scheme, and how they are related to counterterms and renormalized Green functions. We establish that, in the case of an un-coupled Dyson-Schwinger equation, all renormalization schemes are equivalent up to a shift in the renormalization point. The shift between kinematic renormalization and Minimal Subtraction is a function of the coupling and the regularization parameter. We derive a novel formula for the case of a linear propagator-type Dyson-Schwinger equation to compute the shift directly from the Mellin transform of the kernel. Thirdly, we compute the shift perturbatively for three examples of non-linear Dyson-Schwinger equations and examine the asymptotic growth of series coefficients. A second, smaller topic of the present thesis are diffeomorphisms of the field variable in a quantum field theory. We present the perturbation theory of the diffeomorphism field in momentum space and find that the diffeomorphism has no influence on measurable quantities. Moreover, we study the divergences in the diffeomorphism field and establish that they satisfy Ward identities, which ensure their absence from the S-matrix. Nevertheless, the Ward identities leave infinitely many divergences unspecified and the diffeomorphism theory is perturbatively unrenormalizable. Finally, we remark on a third topic, the numerical quadrature of Feynman periods

    Brain Computations and Connectivity [2nd edition]

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    This is an open access title available under the terms of a CC BY-NC-ND 4.0 International licence. It is free to read on the Oxford Academic platform and offered as a free PDF download from OUP and selected open access locations. Brain Computations and Connectivity is about how the brain works. In order to understand this, it is essential to know what is computed by different brain systems; and how the computations are performed. The aim of this book is to elucidate what is computed in different brain systems; and to describe current biologically plausible computational approaches and models of how each of these brain systems computes. Understanding the brain in this way has enormous potential for understanding ourselves better in health and in disease. Potential applications of this understanding are to the treatment of the brain in disease; and to artificial intelligence which will benefit from knowledge of how the brain performs many of its extraordinarily impressive functions. This book is pioneering in taking this approach to brain function: to consider what is computed by many of our brain systems; and how it is computed, and updates by much new evidence including the connectivity of the human brain the earlier book: Rolls (2021) Brain Computations: What and How, Oxford University Press. Brain Computations and Connectivity will be of interest to all scientists interested in brain function and how the brain works, whether they are from neuroscience, or from medical sciences including neurology and psychiatry, or from the area of computational science including machine learning and artificial intelligence, or from areas such as theoretical physics

    Advanced 1,2,3-triazolate-based coordination compounds: from carbonic anhydrase mimics, molecular building blocks, and catalyst supports to electrically conducting spin-crossover MOFs

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    Kuratowski complexes and related metal-organic frameworks (MOF), especially of the MFU-4-type, built from 1,2,3-triazolate-based ligands gained increasing interest in the last years due to their variable side ligands and metal sites. Such materials and their post-synthetic modifications have shown an outstanding potential for applications such as adsorption, capture, separation and kinetic trapping of gases, drug delivery, atmospheric water harvesting, sensing, H2/D2 quantum sieving, investigation of fundamental magnetic phenomena, and in particular catalysis. In this respect, MFU-4-type MOF catalysts were shown to outperform other heterogeneous catalysts for the dimerization and polymerization of olefins with some applications already advancing toward commercial applicability. This thesis mainly aims to extend the functionality of 1,2,3-triazolate-based coordination materials via advanced linker designs, novel framework assembly strategies, and post-synthetic modifications, as well as through a better understanding of the underlying material properties. During this project, several new organic and complex building blocks, as well as advanced framework structures were prepared and characterized. Furthermore, additional emphasis was directed to the investigation and interpretation of resulting physical phenomena like phase transitions, magnetism, and electrical conductivity. The Zn-MFU-4l ([Zn5IICl4(BTDD)3]; H2-BTDD = bis(1H-1,2,3-triazolo[4,5-b][4′,5′-i])dibenzo[1,4]dioxin) and Co-MFU-4l ([Zn1.3IICo3.7IICl4(BTDD)3]) metal-organic frameworks were prepared according to the literature procedures and modified by a post-synthetic side ligand exchange of the chloride anions, which led to MFU-4-type structures featuring organometallic metal-carbon bonds. Overall, five new Zn-MFU-4l structures of the general formula [Zn5IILxCl4–x(BTDD)3] (4 ≥ x > 3; L = methanido, ethanido, n-butanido, tert-butanido, 3,3-dimethyl-1-butyn-1-ido; Zn-MFU-4l-Me, -Et, -n-Bu, -t-Bu, -Butyne) and two new Co-MFU-4l structures, Co-MFU-4l-Me ([Zn1.5IICo3.5IIMe3.1Cl0.9(BTDD)3]) and Co-MFU-4l-OH ([Zn1.4IICo3.6II (OH)3.1Cl0.9(BTDD)3]), were obtained. Such side ligands were not characterized for MFU-4-type MOFs before, although they are presumed responsible for the metal site activation during olefin catalysis reactions, which require organometallic co-catalysts. For this purpose, a combination of simulated and measured IR spectra was developed as well-suited characterization technique for such insoluble materials, which preclude analytical methods like liquid state NMR and mass spectroscopy. A high stability of the organometallic Zn-MFU-4l derivatives was observed, whereas the Co-MFU-4l-Me was of a pyrophoric nature and reacted upon water contact to Co-MFU-4l-OH, which exhibited a CO2 binding mechanism comparable to that of carbonic anhydrase. Synthesis of Kuratowski complexes built from 1H-benzotriazole-5,6-diamine (H-btda) ligands and post-synthetic exchange of the chloride side ligands with Tp/Tp* (Tp= hydrotris(pyrazolyl)borate; Tp* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate) provided us with a variety of six-fold diamine-functionalized molecular building blocks intended for the development of novel MOF construction pathways. Crystallization of those compounds have already led to the assembly of porous metal hydrogen-bonded frameworks (M-HOF), some of which have even exhibited permanent porosity. This is a rare property of this material class, which is still in its infancy with only a few structures reported so far. Overall, five new metal hydrogen-bonded framework assemblies (CFA-20-X ((2,6-lutidinium)+[Zn5X4(btda)6X]−· n(DMF); X= Cl−, Br−), CFA-20-Tp, CFA-20-Tp*, CFA-20-Tp*-DMSO ([Zn5Y4(btda)6]; Y = Tp, Tp*) could be characterized, thus representing a significant contribution to this field of study. Although no MOFs could be crystallized from reactions of these complexes with metal salts, preliminary results have shown that direct incorporation of metal sites is a suitable pathway to convert M-HOFs into more stable MOFs. Taking the functionality of MFU-4-type frameworks to the next level, the novel 1,1',5,5'-tetrahydro-6,6'-biimidazo[4,5-f]benzotriazole (H4-bibt) ligand was developed to potentiate the post-synthetic modification possibilities compared to other MFU-4-type frameworks via introduction of additional and easily accessible biimidazole coordination sites at the linker backbone. This gave rise to the five most sophisticated MFU-4-type structures prepared so far. Post-synthetic Tp ligand exchange in the resulting MFU-4-type CFA-19 ([Co5IICl4(H2-bibt)3]) provided the stable CFA-19-Tp ([Co5IICl0.4Tp3.6(H2-bibt)3]) framework, in which the additional coordination sites were saturated in a third modification step with MIBr(CO)3 (M= Re, Mn) moieties or deprotonated via introduction of ZnEt moieties. The resulting materials exhibit high metal site density single-crystal X-ray structures with over 1700 atoms per unit cell for the ReBr(CO)3@CFA-19-Tp ([Co5IICl0.4Tp3.6(H2-bibt)3·(ReIBr(CO)3)2.8]) and a thermally induced release of all CO ligands for the MnBr(CO)3@CFA-19-Tp ([Co5IICl0.4Tp3.6(H2-bibt)3(MnIBr(CO)3)3]·3.1(MnIBr(CO)X)). Preliminary results also indicate a facile incorporation of other coordination moieties such as MIICl2 (M= PdII, PtII). These proof-of-principle incorporations of coordination moieties and open metal sites render such CFA-19-type scaffolds promising supports for an even larger variety of active species intended for the binding and activation of small molecules in future investigations. Coincidental synthesis of the novel CFA-23 ((((propan-2-yl)oxidanium)+[Mn6IICl5(ta)8]−; H-ta= 1H-1,2,3-triazole) coordination framework provided the opportunity to investigate changes of the resulting magnetic properties in comparison to a similar structure built from 1H-1,2,3-benzotriazole, as well as the ultra-narrow character of the pore channels in CFA-23. High purity samples of the literature-known Fe(ta)2 (H-ta= 1H-1,2,3-triazole) framework were prepared and investigated in detail to unveil its record hysteresis spin-crossover phase transition. Aiming at the use of Fe(ta)2 in surface acoustic wave-based sensor applications, experimental and theoretical insights into the material’s electrical conductivity changes upon adsorption of inert gases were assisted with the measurement of adsorption isotherms and the determination of the resulting isosteric enthalpies of adsorption
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