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The book 'Reinforcment Learning: An Introduction' by Sutton and Barto is the standard text book for introductory courses to reinforcement learning. Next to concrete algorithms and extensive examples the book contains several fundamental results related to Markov decision processes (MDPs) and Bellman equations in Chapters 3 and 4. Unfortunately some proofs are missing, some theorems lack precise formulation, and for some results the line of arguments is quite garbled.
In this note we provide all missing proofs, give precise formulations of theorems and untangle the line of arguments. Further, we avoid using random variables and their expected values. Since we (like Sutton/Barto) restrict our attention to finite MDPs all expected values can be made explicit avoiding overloaded notation and murky conclusions.
This article bridges the gap between introductory literature like Sutton/Barto and research literature containing exact formulations and proofs of relevant results, but being less accessible to beginners due to higher generality and complexity.
The book is the second of four volumes on data science and artificial intelligence. This second volume covers data visualization tool and techniques as well as fundamentals of supervised machine learning: linear regression, artificial neural networks, support-vector machines, decision trees, ensemble methods and more.
Verkehr und Tourismus
(2024)
Tourismus und Mobilität sind untrennbar miteinander verbunden. In erster Linie mag man dabei an die An- und Abreise zur Urlaubsdestination denken. Aber auch für Aktivitäten vor Ort sind Verkehrsmittel bzw. Verkehrsinfrastrukturen von entscheidender Bedeutung. Sie können sogar, z.B. bei Kreuzfahrten oder mehrtägigen Fahrradtouren, einen wesentlichen Bestandteil der Reise ausmachen oder aber, wie etwa imposante Brückenbauwerke oder Dampfbahnen, selbst als Attraktion gelten.
Zahlreiche Beispiele sowie 40 Fallstudien, die auf eigenen Erfahrungen beruhen, illustrieren die aufgegriffenen Themen und sollen beim Leser „Entdeckergeist“ wecken, um interessanten Ideen und Entwicklungen in der Realität auch selbst nachzugehen.
Sustainable Integration of Digitalisation in Nursing Education - An International Scoping Review
(2024)
Abstract: This article reconstructs the path of the German economist Friedrich A. Lutz (1901–75) to American economics. The correspondence with his former teacher Walter Eucken, the founder of the Freiburg school, constitutes a crucial yet unexplored source for the article. Through Lutz's case, this article demonstrates the growing gulf between German and Anglo-Saxon economics during the late 1930s. In his native Germany, Lutz was trained in methodologically and institutionally focused economics, which differed fundamentally from the mathematical economics dominating Anglo-Saxon academia. He realized that an academic career in the United States would be impossible if he did not adapt to the new methods and if he did not abandon the methods of the German tradition. This gave rise to his internal Methodenstreit. After his emigration in 1938, he constantly experienced doubts and tensions because he was convinced that without considering institutions, mathematical economics could never explain the occurrence and essence of macroeconomic phenomena. Despite his stellar career at Princeton, it was only after his move to Zurich in 1953, where he taught history and theory of socioeconomics for the rest of his life, that Lutz could reconcile this internal Methodenstreit.
Die Seminararbeit untersucht die Bedeutung der strategischen Personalentwicklung und Kompetenzförderung im spezialisierten Bereich des Sondermaschinenbaus, mit einem Fokus auf die Praxis der Skill-Checks in einem deutschen Unternehmen. Sie beleuchtet die Auswirkungen des demografischen Wandels, der rasanten technologischen Entwicklungen und der Globalisierung auf den Bedarf an Fachkräften mit spezifischen technischen und sprachlichen Kompetenzen. Durch eine detaillierte Analyse der bestehenden Ausbildungs- und Weiterbildungsprozesse werden Schwachstellen aufgezeigt. Die Arbeit schlägt Lösungsansätze vor, wie durch strukturierte Weiterbildungsprogramme und verbesserte Auswahlverfahren diesen Herausforderungen effektiv begegnet werden kann, um die Wettbewerbsfähigkeit zu stärken.
In diesem Band finden sich das Programm, die Sektionsbeschreibungen und die Abstracts der Vorträge des 15. Deutschen Lusitanistentages, der in der Zeit vom 19.09.-23.09.2023 an der Westsächsischen Hochschule Zwickau stattgefunden hat.
Die Autoren bringen langjährige Erfahrung in verschiedenen Industriebranchen und der akademischen Ausbildung im Lean- und Project and Process Management mit sich. Im Rahmen der beruflichen Tätigkeit und der akademischen Arbeit hat sich immer wieder die Frage gestellt, wie die Philosophie des Lean Management mit den Aufgaben des Projekt Management Office interagieren können. Viele Ansätze des Lean Management, vor allem organisatorische Methoden zeigen eine breite Anwendungsmöglichkeit und sollten somit auch dem Projekt Management Office (PMO) hilfreich sein. Vor einiger Zeit hat sich schon der Begriff des Lean Office [YDF01] etabliert, der aber sowohl in der Büroorganisation als auch der Dokumentenpflege Ansatz findet. Im Rahmen des PMO soll dieser Lean Office auf die bereitzustellenden Prozesse und deren Integration ins Enterprise Ressource Planning Anwendung finden. Je schlanker und effizienter die Projekt- und Programmprozesse einer Organisation aufgestellt werden, desto leichter können diese abgebildet und in die Enterprise Ressource Planning (ERP)-Datenlandschaft übertragen werden. Somit wird ein solider Grundstein über den gesamten Produktprozess gelegt - von der Entwicklung, über die Herstellung bis hin zur schlussendlichen Verwertung schlank, effizient, automatisiert und digitalisiert abgebildet zu sein.
In diesem Artikel sollen einige Aspekte des nachhaltigen Reportings im Sinne der EU-Richtlinien betrachtet werden. Inhaltlich wird die nachhaltige Unternehmensführung unter den Gesichtspunkten der Beschreibung und dem Einfluss der Neuregelung der Transparenzrichtlinien und Offenlegungspflichten auf die Unternehmen fokussiert. Weiterhin wird ein überblicksartiger Einblick in dafür notwendige nachhaltige unternehmerische Prozesse und deren Standards aufgezeigt. Abschließend wird dessen Bezug im Sinne des Reportings sowie eine kritische Bewertung betrachtet.
The research was carried out for the selection of optimal options for the heat supply of multi-apartment buildings, taking as an example several new buildings in Yerevan. The purpose of the study is to confirm the choice of the best method of providing heat in apartment complexes. It was used to calculate and analyze the energy-economic and operational-technical indicators of individual heating boilers, small centralized systems, and hybrid systems to solve this problem. The calculations considered both natural gas tariffs and fluctuations in the value of the Armenian dram against the US dollar. The value of 1 kWh of thermal energy or specific heat capacity has been determined as an important criterion for choosing the most efficient method of heat supply, considering the careful analysis of almost all variable factors.
Conceptual Approach to an AI-Based Adaptive Study Support System for Individualized Higher Education
(2023)
In the context of the digital transformation, the targeted implementation of AI-based or AI-supported technologies in "teaching & learning" as well as "administration & service" holds considerable potential for organizational change and quality enhancement for higher education institutions. The use of AI in higher education teaching and services lags behind the level in research. Therefore, holistic solutions must be planned and implemented in unity of teaching and research for the AI-based support of the stakeholders’ inclusive administration, the further development or the establishment of new digital study programs and offers as well as the prospective qualification of university staff in the field of AI. The solutions must be analyzed, systematized, and structured to generate a conceptual approach via an integrated architecture with adaptive services.
This paper is an evolution of the concept presented at the Learning Ideas Conference 2022 and includes, in addition to explanations of the current state of the arts, the presentation of a systems-oriented approach for AI in higher education as well as the conception of the student lifecycle management at the author’s university. The paper ends with the presentation of a concept regarding a decision support system for individualized studying.
Abstract: Die Automobilindustrie befindet sich seit Jahren im Ausnahmezustand, da der Wechsel von einer Einheitsantriebsart hin zu einem Mix an Antriebsarten parallel zu globalen Krisen bewältigt werden muss. Der vorliegende Beitrag liefert dazu beispielhafte Betrachtungen zur indikativen Bewertung der gegensätzlichen Produktionsstrategien Mix- oder sortenreiner Produktion von Fahrzeugen mit alternativen und konventionellen Antrieben. Die Erkenntnisse können genutzt werden, um Modelle zur Wahl der richtigen Produktionsstrategien abzuleiten.
Zusammenfassung: Die für die Planung des Materialflusses relevanten Fertigungsprozesse lassen sich sehr genau planen, beispielsweise über die Leistung der Maschine (Durchsatz je Zeiteinheit). Bei der Planung eines Projektes spielen logistische Prozesse, die zu den Kernprozessen eines Unternehmens gehören, eine wichtige Rolle. Jedoch werden sie meist nur grob terminiert und mit großen Puffern kalkuliert. Dies kann zu einer Verlängerung der Projektdauer führen. Für eine genauere Terminierung eines Projektes ist es daher entscheidend, die Dauer der logistischen Prozesse mindestens in dem Maße wie die Fertigungsprozesse zu ermitteln, um das Risiko einer Projektverzögerung zu minimieren.In diesem Beitrag wird deshalb eine Methode zur datenbasierten Schätzung von Prozessdauern mit dem Ziel der Wiederverwendung von Projektwissen vorgestellt, die es dem Projektmanagement ermöglichen soll, Dauern von logistischen Prozessen präziser zu schätzen als das aktuell basierend auf Erfahrungswissen erfolgt. Besonderes Augenmerk liegt dabei auf der Herleitung der Entwurfsaktivitäten. Durch die Anwendung der Methode soll das Projektmanagement von einer genaueren, datenbasierten Schätzung von (Logistik‑)Prozessdauern profitieren und so entstandenes Wissen über einen Ontologieansatz wiederverwenden können.
Abstract: The demand for thorough disinfection within ambulances is essential, given the in-vehicle medical procedures and the potential high risk of infections due to patients' open wounds. One solution that can address this hygiene challenge involves the application of reactive products generated from atmospheric (air) oxygen and water vapor, activated through the use of cold plasma. Cold plasma's charged particles perforate the cell membranes of microorganisms. This process does not work in human cells, as proteins in the form of enzymes within the body break down the cold plasma and protect the cells. The study was done on an ambulance that was contaminated in eight places. Samples were taken from each site, and two surfaces measuring approximately 8 × 8 cm were carefully sealed and marked. These surfaces were deliberately contaminated by applying an Enterococcus faecium suspension of 8.5 × 107 CFU/mL using a sterile cotton swab. It was followed by the disinfection procedure, that was initiated with the PLASMOCAR device. It was positioned on the front workspace and operated for a duration of 30 min, utilizing the vehicle's onboard voltage. Throughout the operation, all doors and windows were closed and the vehicle's air conditioning system remained active. After the completion of the disinfection process, samples were collected from the surfaces for bacterial counts. A reduction of 3.73 log levels in initial bacteria was accomplished within the rescue vehicle for Enterococcus faecium, equivalent to a 10–fourfold reduction in bacteria, eliminating up to 99.99% of the initial microorganisms. This success makes the process well-suited and convenient as an ongoing "background" procedure to enhance the established disinfection procedures. The established disinfection procedures outlined in the hygiene plan must be promptly implemented whenever mechanical surface cleaning is required. The use of PLASMOCAR offers an extra layer of protection and security, significantly decreasing the risk of microorganism transmission through cross-contamination and aerosols. This is a significant benefit for the well-being of both staff and patients.
The book is the first of four volumes on data science and artificial intelligence. This first volume covers fundamentals of data science: an introduction to Python programming, software libraries for data management, techniques for working with big data. It contains many exercises and projects with real-world data.
Ziel dieses Beitrags ist die Analyse der folgenden Fragen an das Wahlprogramm Bolsonaros für die brasilianischen Präsidentschaftswahlen 2018: Was sind die Folgen bezüglich des Inhalts und des Ethos des Kandidaten dessen, dass sein Wahlprogramm in Form einer Power Point-Präsentation publiziert wird? Welche Funktion haben die religiösen Textteile für das Ethos des Kandidaten? Welche explizite und implizite Hierarchie der sittlichen Güter und Werte lässt sich aus diesem Programm rekonstruieren? Unter anderem wird die Kohärenz zwischen der Hierarchie der sittlichen Güter, die Privateigentum und nicht das menschliche Leben als höchstes sittliches Gut betrachtet, und der während seiner Regierung verfolgten Nekroplitik aufgewiesen
This paper deals with systematic approaches for the analysis of stability properties and controller design for nonlinear dynamical systems. Numerical methods based on sum-of-squares decomposition or algebraic methods based on quantifier elimination are used. Starting from Lyapunov’s direct method, these methods can be used to derive conditions for the automatic verification of Lyapunov functions as well as for the structural determination of control laws. This contribution describes methods for the automatic verification of (control) Lyapunov functions as well as for the constructive determination of control laws.
Liquid deposition modeling is an energy-efficient, additive manufacturing process for pasty materials. Physical material properties were determined for a water-based paste consisting of the binder carboxymethyl cellulose and wood flour. A continuously operating dual screw extruder was developed, which was used to manufacture a table frame with a height of 18 cm.
Electrical and thermal measurements were conducted during the plasma electrolytic polishing (PEP) of cemented tungsten carbide (WC-Co) materials to characterize energetic aspects of the process in relation to the temporal development of the gaseous layer near the workpiece. The power transferred to the workpiece is determined using a calorimetric probe and employing the time derivative of the temperature curve. It shows distinct heating phases due to the generation of the gaseous layer. At the beginning of the process, a typical power of 367 ± 17 W is transferred to the workpiece of a surface area of 14 cm2. At longer process times, a stabilized gaseous layer limits the power transferred to the workpiece to 183 ± 3 W. In an attempt to describe the heat transferred to the electrolyte, the electrolyte temperature was measured using a thermocouple situated 15 mm away from the workpiece. The local electrolyte temperature increases from 70 to 81 °C for an immersion depth of 20 mm. Moreover, the spatiotemporal development of the electrolyte temperature was obtained by 2D-hydrodynamic modeling using COMSOL Multiphysics®. The modeling results for the local temporal temperature development are in excellent agreement with the experimental values when the turbulent model is applied up to t = 65 s. Afterward, the laminar model leads to a better agreement. Furthermore, line scan x-ray photoelectron spectroscopy revealed that aliphatic carbon was preferentially removed. Only a slight compositional gradient in the vertical direction after the PEP process was observed.
Models of artificial root canals are used in several fields of endodontic investigations and pre-clinical endodontic training. They allow the physical testing of dental treatments, the operating of instruments used and the interaction between these instruments and the tissues. Currently, a large number of different artificial root canal models exist whose geometry is created either on the basis of selected natural root canal systems or to represent individual geometrical properties. Currently, only a few geometric properties such as the root canal curvature or the endodontic working width are taken into consideration when generating these models. To improve the representational capability of the artificial root canal models, the aim of the current study is therefore to generate an artificial root canal based on the statistical evaluation of selected natural root canals. Here, the approach introduced by Kucher for determining the geometry of a root canal model is used, which is based on the measurement and statistical evaluation of the root canal center line’s curvatures and their cross-sectional dimensions. Using the example of unbranched distal root canals of mandibular molars (n = 29), an artificial root canal model representing the mean length, curvature, torsion and cross-sectional dimensions of these teeth could be derived.
The aim of this study was to investigate the antimicrobial efficacy of different disinfection protocols in a novel Enterococcus faecalis biofilm model based on a visualization method and to evaluate the potential alteration of dentinal surface. A total of 120 extracted human premolars were allocated to 6 groups with different irrigation protocols. The assessment of the effectiveness of each protocol and the alteration of dentinal surface were visualized by using SEM and fluorescence microscopy (DAPI). A dense E. faecalis biofilm with a penetration depth of 289 μm (medial part of the root canal) and 93 μm (apical part) validated that the biofilm model had been successfully implemented. A significant difference between the 3% NaOCl groups and all the other groups in both observed parts of the root canal (p < 0.05) was detected. However, the SEM analysis revealed that the dentinal surface in the 3% NaOCl groups was severely altered. The established biofilm model and the visualization method based on DAPI are appropriate for bacterial quantification and evaluation of the depth effect of different disinfection protocols in the root canal system. The combination of 3% NaOCl with 20% EDTA or MTAD with PUI allows the decontamination of deeper dentine zones within the root canal but simultaneously alters the dentinal surface.
Certifying Fully Dynamic Algorithms for Recognition and Hamiltonicity of Threshold and Chain Graphs
(2023)
Solving problems on graphs dynamically calls for algorithms to function under repeated modifications to the graph and to be more efficient than solving the problem for the whole graph from scratch after each modification. Dynamic algorithms have been considered for several graph properties, for example connectivity, shortest paths and graph recognition. In this paper we present fully dynamic algorithms for the recognition of threshold graphs and chain graphs, which are optimal in the sense that the costs per modification are linear in the number of modified edges. Furthermore, our algorithms also consider the addition and deletion of sets of vertices as well as edges. In the negative case, i.e., where the graph is not a threshold graph or chain graph anymore, our algorithms return a certificate of constant size. Additionally, we present optimal fully dynamic algorithms for the Hamiltonian cycle problem and the Hamiltonian path problem on threshold and chain graphs which return a vertex cutset as certificate for the non-existence of such a path or cycle in the negative case.
Sometimes cranioplasty is necessary to reconstruct skull bone defects after a neurosurgical operation. If an autologous bone is unavailable, alloplastic materials are used. The standard technical approach for the fabrication of cranial implants is based on 3D imaging by computed tomography using the defect and the contralateral site. A new approach uses 3D surface scans, which accurately replicate the curvature of the removed bone flap. For this purpose, the removed bone flap is scanned intraoperatively and digitized accordingly. When using a design procedure developed for this purpose creating a patient-specific implant for each bone flap shape in short time is possible. The designed skull implants have complex free-form surfaces analogous to the curvature of the skull, which is why additive manufacturing is the ideal manufacturing technology here. In this study, we will describe the intraoperative procedure for the acquisition of scanned data and its further processing up to the creation of the implant.
This article aims to identify the status quo of sustainability covenants firstly, secondly analyze their possibilities in enhancing sustainability performance and thirdly present further research directions. Covenants are additional contractual agreements mainly used in financial contracts, e.g. loans. They often focus on financial performance indicators, e.g., equity and net debt ratio, which the borrower must fulfil. However, the purpose of this article is to present a new approach to non-financial covenants, so-called sustainability covenants. Therefore, also nowadays ecological and social challenges are addressed. Banks have a huge impact on sustainable development by introducing more non-financial indicators in evaluating the creditability of borrowers. As a key hypothesis, this article argues that the approach of integrating ecological and social objectives through non-financial covenants is underrepresented in economic and business practice. Therefore, this article wants to examine how those objectives can be integrated into the financial concept of covenants and rely on research towards an integrative sustainability approach. In addition, a systematic literature review was conducted from October 2022 to July 2023 to analyze the status quo and derive future research directions. The review was based on two databases – Google Scholar and Scopus. As one key result, it was revealed that there is scarce existing literature on sustainability covenants, which refers to them as a policy measure. Only a few publications analyze their usage in financial contracts. However, this study implies the necessity for further research on sustainability covenants, emphasizing that they are powerful indicators to enhance the sustainability performance of the borrower.
Model predictive control (MPC) is a promising approach to the lateral and longitudinal control of autonomous vehicles. However, the parameterization of the MPC with respect to high-level requirements such as passenger comfort, as well as lateral and longitudinal tracking, is challenging. Numerous tuning parameters and conflicting requirements need to be considered. In this paper, we formulate the MPC tuning task as a multi-objective optimization problem. Its solution is demanding for two reasons: First, MPC-parameterizations are evaluated in a computationally expensive simulation environment. As a result, the optimization algorithm needs to be as sample-efficient as possible. Second, for some poor parameterizations, the simulation cannot be completed; therefore, useful objective function values are not available (for instance, learning with crash constraints). In this work, we compare the sample efficiency of multi-objective particle swarm optimization (MOPSO), a genetic algorithm (NSGA-II), and multiple versions of Bayesian optimization (BO). We extend BO by introducing an adaptive batch size to limit the computational overhead. In addition, we devise a method to deal with crash constraints. The results show that BO works best for a small budget, NSGA-II is best for medium budgets, and none of the evaluated optimizers are superior to random search for large budgets. Both proposed BO extensions are, therefore, shown to be beneficial.
Abstract: Duplex steels are used for applications that require high strength and ductility combined with good corrosion resistance. An economical welding technology to handle these steels is achieved by combining the MIG and TIG arc processes. The aim is to improve welding speed and quality by utilizing a TIG-MIG hybrid welding process to join 1.4462 duplex steel with a thickness of 2 mm. The interaction between the two arcs, caused by the blowing effect, is an enormous challenge that can be counteracted with a defined torch position and current modulation. For this purpose, a variation of the MIG (pulsed and AC pulsed arc) and TIG process (AC and pulsed DC) took place. The influence of electrical parameters on process stability and material transfer was investigated. For analysis, an evaluation of high-speed recordings (5000 frames per second) and synchronized measured current/voltage curves (200 kHz) is carried out. Based on a number of selected specimens, a welding procedure test according to ISO 15614-1 is performed to determine the welding seam quality. The test includes the characterization by tensile and hardness testing and macroscopic and microscopic examination. Additionally, the specimens are examined according to ISO 5817.