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This master's thesis focuses on developing a robust framework for co-simulating microscopic traffic scenarios and vehicle dynamics, leveraging the capabilities of SUMO and CARLA. The essence of this research lies in its meticulous analysis of existing simulation tools, leading to identifying the most effective co-simulation strategies and intercommunication methods. A comparative study elucidates the strengths and limitations of these methodologies, guiding the selection of an optimal approach.
Central to the methodology is a thorough understanding and application of SUMO and CARLA, enhanced by the strategic implementation of intercommunication methods. The detailed integration of these tools and the introduction of test automation significantly boost simulation efficacy. The framework's reliability and accuracy are rigorously validated through well-defined procedures and metrics, ensuring fidelity in simulation results.
Key to this research is the design of experimental scenarios that reflect real-world traffic conditions underpinned by carefully chosen simulation parameters. These scenarios are pivotal in validating the co-simulation framework's performance, supplemented by a performance cost analysis focusing on processing efficiency. The thesis culminates with a critical discussion of the findings, addressing the research objectives and posing solutions to identified challenges. Potential areas for future enhancements are explored, highlighting the framework's limitations.
In conclusion, this thesis contributes significantly to the field of traffic simulation for autonomous driving technologies. It presents a comprehensive co-simulation framework, offering researchers and engineers a sophisticated tool for advanced testing and validation. The insights and recommendations provided are instrumental for ongoing research and development in this rapidly evolving domain.
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.
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.
The traffic calming measures aim to slow down traffic speed, accident frequency, and reduction of through traffic caused mainly by motorized vehicles in residential areas. These measures are primarily addressed to the specific streets and lead the necessary or remaining traffic to drive in a restrained or considerate manner. While these measures are designed to prevent conflicts between pedestrians and motorists, they impose unstable traffic patterns and are sometimes unable to accommodate the increasing motor vehicle flows, as they are concentrated only on certain streets.
This paper investigates area-wide urban traffic calming techniques from existing projects. It explains how traffic regulatory and structural measures link together or separately to restrict the movement of motor vehicles traveling through neighborhood streets and divert them to main roads. The implemented sample measures were illustrated and described with photos of their current locations.
In this thesis, the district Äußere Neustadt was defined as a model area in Dresden to analyze and redesign the existing mobility plan in order to reduce the MIV flows with the main objectives of giving space for pedestrians, cyclists, and public transport. The district's street infrastructure is heavily impacted by the presence of parked vehicles, raising challenges to the safe movement of both bicyclists and oncoming motor vehicles. In the frame of the model project initiative - "Woche des guten Lebens", the volunteer team has designed a traffic experiment and carried out an online survey to assess citizens' opinions of the Äußere Neustadt. The analyses demonstrate and emphasize the necessity of political support and interactive communication with citizens regarding the area-wide radical sustainable mobility plan. Considering the positive feedback of the citizens, the new mobility plan was realized in this paper.
Area-specific traffic calming techniques such as diagonal or cross barriers, zone speed limits, offsets, one-way streets, etc. were analyzed from the implemented projects to determine the appropriate solutions for the specified streets. The district's existing traffic network and the new solutions offered were visualized using QGIS software.
The implemented new traffic plan will lead to more space for pedestrians and bicycle traffic and a reduction in traffic noise.
The objective of the study is to improve the functionality of the Virtual Reality Laboratory (VR Labs) of the Faculty of Automotive Engineering and enhance its applicability in Road Traffic Engineering education and training at the University of Applied Sciences Zwickau (WHZ). In this study, a comprehensive description of Virtual Reality (VR) and Augmented Reality (AR) as well as their wide application in education has been given.
An insight into the VR Labs of the Faculty of Automotive Engineering at WHZ is provided. The study built and proposed eight use cases of VR Labs in road traffic engineering training and education at WHZ. The limitations and barriers in deploying application cases are analyzed and suitable solutions are given. The adoption of virtual reality can be an easy transition based on BIM modeling software development, and 3D and 360 degrees scanning.
An extension of the VR Labs application for other areas of education at WHZ has been identified. In addition, technologies, areas of application, and future research directions are mentioned. Innovations such as 3D modeling and BIM-based workflows that are being encouraged through the development of content-created engines will provide students with opportunities for using VR/AR on road traffic and infrastructure projects in the future.
BIM (Building information modeling) is becoming a reliable method for the planning, design, implementation, and maintenance stages of construction projects due to its ability to improve the quality of project stages, reduce project time, and ensure costs. From 2000 onwards, the trend of using BIM method increased in the world. And in the last decade, many developed countries have introduced BIM as a reasonable and efficient method with the aim of optimizing project stages, and many employers have paid attention to training and persuading consulting and contracting companies.
In the meantime, the BIM method is constantly being updated. Many researchers are looking to modify existing sub-methods to help the project achieve all of the great BIM goals.
Although BIM has great goals such as those mentioned, in some cases, projects are not able to achieve all of them for various reasons.
This thesis has put its hypothesis on the existence of deficiencies in the content of the EIR (Employer's Information Requirements) document and its writing methods.
This document, which is a kind of project guide in BIM format, is compiled by the client and its task is to announce the needs of the client to the members involved in the project and to clarify the different stages of the project. In many construction projects, due to the complexity of the EIR, the employer's lack of attention to some information, or the failure to include the opinions and views of the project's stakeholders in the writing of this document, the EIR cannot fulfill its key role with its maximum potential performance in the project.
This thesis is written with the aim of finding a comprehensive solution to maximize the power of the BIM method in a project through correct and complete document writing.
Also, this thesis seeks to prove its claims by focusing on the ABS 38 project as a case study. In addition, a literature review on important and key issues in the field of BIM and EIR documents has been done. After that, a scoring system (Relative rating method) was used to find the best variant and compare it to prove the proposed hypothesis.
Finite element Analysis is a powerful tool that enables a thorough examination of the physical and mechanical aspects of various objects, yielding insights that would otherwise be difficult to obtain. In the context of the guitar industry, this technology can be used to determine the role of internal bracing structures with a high degree of precision. Specifically, FEM is commonly utilized to analyze the natural vibration frequency of guitars and to gain a better understanding of their vibrational behaviour. Although there are many sources that describe the impact of braces on the natural frequencies of guitar tops, there exists a paucity of research that delves into how these structures achieve their effects.
The purpose of this paper is to employ FEM to examine the effect of braces on the soundboard and to contrast the results with those obtained from an actual soundboard fabricated by the author. Through simulation, we aim to elucidate the influence of various factors such as position, height, and profile on the soundboard's performance. However, it is important to note that there may be discrepancies between the simulation results and the actual performance of the soundboard owing to measurement errors and constraints associated with manual production. As a result, the data generated by this study should not be regarded as reference data.
Objective: Sagittal balance (SB) plays important role in the successful treatment of spinal disorders. Segmental lordosis is an important SB parameter in spinal surgery and diagnosis, which can help to ensure proper surgical planning and better postoperative outcomes. The manual measurement of segmental lordosis is associated with problems such as time-consuming procedures, high error rates, and poor reproducibility.
The bachelor thesis proposes a solution by exploring and evaluating a more efficient and reliable AI-based method for determining segmental lordosis in preoperative patients, which is compared to measurements made by experienced physicians.
Methods: hidden due to a non-disclosure agreement.
Results: hidden due to a non-disclosure agreement.
Conclusions: hidden due to a non-disclosure agreement.
In this project we develop an intelligent water meter based on software solutions offered by the IOTA Foundation. The water meter allows the customer to map water usage in real-time and pay water on demand, as well as the water provider to map water usage on a greater scale, regulate water supply during low- demand phases and offers regulatory functions to prepare for drought or humid climate, and to incentivise sustainable water usage in high-demand fields like agriculture. This functionality is phrased into a research issue:
Invention of a working prototype to demonstrate the IOTA Streams and Wallet protocols for a meter with additional focus on economic efficiency and the technical preparation of scalability.
Utilizing the IOTA streams protocol, a next generation secure data connection is established between the water meter and a server-sided software application. On this connection, water consumption is mapped into a data bench, and informative data and commands are issued to the graphical interface of the meter.
The IOTA wallet library is leveraged to provide customer accounts corresponding to their meter. IOTA tokens can be send to the account, which grants access to water in a matter of seconds. Depending on the regulatory scenario, water flow can be stopped as soon as the account is exhausted (i.e. public well), or an overdraw can be established in order to guarantee fulfilment of basic human rights (i.e. private households).
Since pricing data can be calculated server-sided and water consumption is mapped in very narrow intervals of as low as 4 seconds, the price can be used as tool to regulate consumption.
The physical components include an electrical ball valve to shut down water flow automatically, a command line interface to provide informative data,, a Raspberry Pi running the client-sided software application, and a water meter with MBus-Interface, as well as a Controlling Board to connect the Raspberry Pi with both peripheral devices.
The finished prototype shows, that water consumption can be mapped on a highly secure level, in near real-time, from afar, flexible for most applications.
Despite lacking sufficient evidence, the shift to automated mobility has often been regarded as progress towards a safer road transport system. Following the introduction of the first production car that has been officially certified as Level 3 earlier in 2022, the driver can shift their role to only as a fallback when the automated driving system reaches its limit of the Operational Design Domain. In the event of an accident, though, the matter will only get even more complicated, especially in the process of unravelling the party that was performing the Dynamic Driving Task at the time of the collision. An accident investigation is done to provide insight into how it occurred and uncover the liable parties. This thesis reviews various methods reconstructing an accident scene, such as photogrammetry and laser scanning, as well as elaborating the relevant data that has already available in the vehicle and from the infrastructure. Recommendations are also presented on for the future data collection, specifically in the scenario of automated driving, to improve such practice.
Automotive transportation plays an important role in everyday urban life. The motorization is increasing along with rising population every year. The constant increase of cars causes various problems in big cities. One of the major problems is parking. Parking search traffic contributes to about 30% of the traffic volume in city centers. This leads to problems like congestion, road accidents, increase of fuel emission due to the circling of cars inside the city looking for parking facilities, environmental pollution etc. Most of the cities face this problem not because of the unavailability of parking spots in parking facilities but rather because drivers don't have the right information on where to park. This can be solved by providing proper guidance about the parking facilities to the drivers. For this, efficient parking space management including the design of a suitable parking guidance system is required. The Entsorgungs and Vekehrsbetrieb (EVB) Wismar has been responsible for the parking space management in the city since 2012 and is implementing the parking space concept in Wismar that was approved by the town council. So far, there is a static parking guidance system in Wismar, which consists of 20 locations with signs pointing to six parking facilities. The Entsorgungs und Vekehrsbetrieb (EVB) intends to replace the static parking guidance system of the Hanseatic City of Wismar with a dynamic parking guidance system (DPGS). The aim of my master thesis is to create a concept for the development of a dynamic parking guidance system in the Hanseatic city of Wismar, including the technical operation and possible implementation, taking autonomous driving into account.
This research investigates the Leipzigerstraße and Gießereistraße intersection in Rackwitz to enhance safety and sustainable transportation. The study analyzes existing designs that experience accidents and proposes a design plan of mini roundabout to improve safety while using the guideline Anlage von Kreisverkehren. In this project, the roundabout is planned according to the currently valid guidelines from phase 2 of the HOAI (Fee Structure for Architects and Engineers). Rainwater management strategies and traffic quality of the roundabout are considered. Additionally, cyclist-friendly paths connecting Rackwitz and Zschölkau are developed in line by using guideline ERA. The proposed roundabout design and elevated cycle paths are identified as effective solutions to enhance safety and support eco-friendly transportation. By adhering to established guidelines and prioritizing safety, this research contributes to creating a secure and sustainable urban transportation network.
WHO estimates that 1.25 million people worldwide pass away in traffic accidents each year. Accidental damage to the economy costs USD 520 per year. Road traffic accidents account for 2.1% of all fatalities worldwide. In total, 50,000 people die in Europe each year. One of the most significant economic and social issues, traffic accidents result in thousands of fatalities and serious injuries each year in Germany and around the world. Whenever there is an accident involving vehicles, trucks, motorized two-wheelers, bicycles, or pedestrians that results in casualties or property damage, the questions of what caused the accident and how it could have been prevented naturally arises: whether it was due to human factors (e.g., carelessness, speeding, or drinking), vehicular flaw (e.g., faulty brakes, a faulty chassis, or old tires), road surface, poor visibility, and so on. The list of possible explanations is really long. The problem is to implement effective steps to prevent accidents from happening in the first place, regardless of what caused the mishap.
The German federal states of Sachsen, Sachsen-Anhalt, Brandenburg, Hessen, and cities of Hamburg, and Bremen are examined in this study's analysis of accidents. This study aims to (i) identify the human factors, environmental factors, and road/infrastructural factors that lead to human failures which cause road accidents, and (ii) explore ways of mitigating these accidents.
1 In an increasingly populated and technological world, manufacturing processes have become faster and data more voluminous. With this comes the need to store this massive production data and use real-time data monitoring tools to facilitate decision making in a plant. Concepts, derived from Pharma 4.0.
| 2 In the manufacturing environment there is, however, a big challenge in data collection and transmission, i.e. the communication between different equipments, sensors, and software. Since each manufacturer tends or has tended to use its own standards for programming and manufacturing the devices and tools.
| 3 Another major challenge is the secure transmission of data to avoid theft and cyber attacks, thus affecting the company's credibility and financial losses.
| 4 In this project the data transfer from Programmable Logic Controller (PLCs) was performed through the Matrikon Server and an interface belonging to the OPC Foundation, this technology allows the collection of data from different sources and delivers them safely to the process visualization software in a single language.
| 5 For software and hardware installation in a regulated environment, standards and validation methods need to be followed before, during and after installation of the required system.
| 6 This project aims to transfer data continuously and contemporaneously from a local source to the could environment and present the validation method used by pharmaceutical industries to validate this process in a GMP-regulated environment.
| 7 For the performance of the software installation, documents have been prepared and used to record and evidence the procedure. These documents were prepared and executed based on standards and methods relevant to the validation process.
| 8 The workers were also trained to know how to handle the data coming from production, and to be able to extract the value from it for different sectors, such as quality, raw material sector, energy sector, etc.
| 9 Finally, improvements were suggested for the documents and validation process used in this project. Since this installation will be used as a basis for future customer installations, not only for interfaces, but also for 1st and 2nd generation connectors.
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: 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.
Since Carbon emissions are soaring all over the atmosphere, the world suffers from significant problems daily. It has become apparent that reliance on single occupancy vehicle transportation is unsustainable, expensive, and primarily harmful to humankind. Rural areas are frequently abandoned while expanding
transportation infrastructure as urbanisation grows. In rural areas, a lack of adequate and inexpensive transportation options leads to seclusion and restricted access to products, facilities, and job opportunities.
This study explores the potential of alternative transportation methods to improve mobility in rural areas. The objectives of the research are to expand knowledge on sustainable alternative transportation in rural regions and to offer practical solutions for enhancing accessibility and mobility for rural residents.
The study employed a mixed-method approach, including a literature review, a survey, and interviews with participants in two rural regions, Mosel and Oberrothenbach. The findings suggest that the transportation challenges faced by rural inhabitants can be effectively and sustainably addressed through walking and by using alternative transportation modes, such as cycling and public transit. This thesis provides a range of ideas and strategies to improve regulations, programs, and infrastructure related to alternative transportation modes in rural areas. This study dives into the characteristics and requirements
of these places using a combination of quantitative and qualitative surveys done in representative two rural regions to recommend successful alternative transportation solutions of On-Demand Transport Services and Electric or Trolley bus Services for daily commutes. The findings underline the need for flexible, multimodal, and on-demand transit choices, as well as the need for community participation and technology integration.
Natural varnishes have been used for centuries by musical instrument makers to protect the instruments for climatic, aesthetic and acoustic reasons. The effects of varnishes on the protection of the wood surface, as well as their aesthetic parameters, are easier to verify and compare visually, but the comparison of their acoustic effects has always been challenging and debated.
In fact, varnish layers have a small effect on the vibration properties of wood. For example, the effect of a decrease or increase in humidity on the vibration properties of wood is sometimes equal to the effect of several layers of varnish. Because of this small amount of effect, measuring this effect is also difficult and challenging.
Our strategy in this study is to obtain the clearest possible results by comparing the effect of only two types of oil varnishes with completely opposite elastomechanical properties and increasing the number of samples varnished.
The samples were measured before and after each varnish layer using conventional methods for measuring vibration properties, and the average results of the same samples were discussed and analyzed.
Overall, the amber varnish obviously has a more negative effect on the vibration properties of the violin plates compared to the colophony varnish.
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.
Research and studies have indicated that rural highways globally exhibit a disproportionately high incidence of accidents and fatalities, which can be attributed to inadequate traffic safety measures. This paper primarily examines the causes of inadequate traffic safety, with a particular emphasis on factors associated with road conditions. These causes can be broadly categorized into human factors, road factors, and vehicle factors. Indeed, the movement of vehicles on these rural roads is characterized by unrestricted traffic flow, whereby the driving stability of a vehicle is primarily impacted by factors such as road alignments and surface conditions. Single-vehicle run-off-road crashes frequently exhibit a correlation with insufficient road conditions. Hence, enhancing the alignment design of roadways can prove to be efficacious in minimizing the occurrence of traffic accidents. However, constraints may arise in the context of rural roads, thereby imposing limitations on designers and engineers in their ability to modify road design. Therefore, it is imperative to explore alternative measures to enhance road safety as required. The objective of this study is to analyse driving behaviour on a two-lane rural road in Germany, taking into consideration the varying alignments of the road. The WHZ static simulator is an innovative technological tool utilized within the field of road design analysis, specifically for the purpose of evaluating driving behaviour. Speed, lateral positions, and are the primary parameters utilized in the evaluation of driving behaviours.
Keywords: Driving Simulators, Driving Behaviour, Traffic Safety, Trajectory Classification
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.
Hypotrochoidal profile contours have been produced in industrial applications in recent years using two-spindle processes, and they are considered effective high-quality solutions for form-fit shaft and hub connections. This study mainly concerns analytical approaches to determine the stresses and deformations in hypotrochoidal profile shafts due to pure bending loads. The formulation was developed according to bending principles using the mathematical theory of elasticity and conformal mappings. The loading was further used to investigate the rotating bending behaviour. The stress factors for the classical calculation of maximum bending stresses were also determined for all those profiles presented and compiled in the German standard DIN3689-1 for practical applications. The results were also compared with the corresponding numerical and experimental results, and very good agreement was observed. Additionally, based on previous work, the stress factor was determined for the case of torsional loading to calculate the maximum torsional stresses in the standardised profiles, and the results are listed in a table. This study contributes to the further refinement of the current DIN3689 standard.
The purpose of this article is to revise the literature on how theories have been utilized in investigating third-parties (for example, Non-Governmental Organizations, certifying organizations, among others) in Sustainable Supply Chain Management. Based on that, we derive future research directions. For revising the literature in a structured manner, the articles use the systematic literature review as the method of choice. Only half of the identified articles utilize theories for investigating third-parties in Sustainable Supply Chain Management. In addition, major theories are overweighed. This predomination leads to influencing the conceptualization of third-parties in Sustainable Supply Chain Management. Future research opportunities exist in broadening the utilization of theories and methods applied in the field, investing in under-explored aspects and broadening the scope of testing and building frameworks. Based on the synthesizing, propositions supplement future research directions. The novelty of this article lies in its investigation of how theories have been used in investigating and conceptualizing third-parties in Sustainable Supply Chain Management. By that, it contributes with a state-of-the-art view on the important topic of sustainability and how third-parties could solve sustainability challenges. With that, the article is a first attempt and step for extending the academic literature and practice with rethinking classic ways of managing sustainability and utilize out of the box ideas.