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Hybrid manufacturing of titanium Ti-6Al-4V combining laser metal deposition and cryogenic milling
(2020)
Hybrid manufacturing, which, e.g., combines additive manufacturing with conventional machining processes, can be a way of overcoming limitations currently encountered in additive manufacturing. Cryogenic milling might be a viable option for hard-to-cut materials, as it leaves a contamination-free surface and can increase surface quality and tool life compared to conventional cooling concepts. In this study, the influence of cryogenic milling with carbon dioxide on titanium Ti-6Al-4V specimens manufactured with laser metal deposition (LMD) was investigated regarding tool wear and surface integrity in comparison to dry machining and machining with cooling lubricants. Moreover, additional layers of material were deposited on top of conventionally and cryogenically machined surfaces by means of LMD. The interface zone was then examined for defects. The milling process was closely monitored by means of thermal and high-speed imaging. Optical and tactile surface analysis provided evidence that lower roughness values and improved surface qualities could be obtained with cryogenic machining in comparison to dry machining. Moreover, significantly less tool wear was observed when a cryogenic cooling medium was applied. Although the utilization of conventional cooling lubricants resulted in satisfying surface qualities, substantial residual contamination on the milled surface was detected by means of fluorescence analysis. These contaminants are suspected to cause defects when the next layer of material is deposited. This is supported by the fact that pores were found in the weld bead applied on top of the milled specimens by means of LMD. Conversely, cryogenic machining resulted in very clean surfaces due to the residue-free evaporation of the coolant. Hence, a good metallurgical bonding between the weld bead and the milled substrate could be achieved. The results indicate the great potential of cryogenic milling in hybrid manufacturing, especially in terms of intermediate machining, as it provides residue-free surfaces for subsequent material deposition without an additional cleaning step and can significantly prolongate tool life.
Dissipation energy based parameter identification of anisotropic linear viscoelastic composites
(2020)
The current work presents a relaxation analysis based procedure to identify effective material parameters of the multiaxial generalized Maxwell model (GMM) by a numerical homogenization of the microscopic dissipation energy density for anisotropic linear viscoelastic composites. The employed GMM enables the derivation of a thermodynamically consistent constitutive law and a function of the dissipation energy density for direction‐dependent viscoelastic materials. The identity of this energy function to the microstructure's homogenized dissipation energy density is utilized for the identification of effective relaxation times. Furthermore, the identified relaxation times enable a simple determination of the remaining stiffness parameters. Finally, the presented procedure is demonstrated and evaluated for a randomly endless fibre‐reinforced plastic with a polymer matrix exhibiting a significant viscoelastic behaviour.
The purpose of this study is to examine the relationship between contextual work-related factors in terms of job demands (workload-WL) and job resources (work flexibility-WF), work-life conflict (WLC) and the burnout dimension emotional exhaustion (EE) in a large population-based sample. Building on the job demands resources model (JDRM), we have developed the hypothesis that WL has an indirect effect on EE that is mediated by WLC. We conducted a secondary analysis using data from the Dresden Burnout Study (DBS, N = 4246, mean age (SD) = 42.7 years (10.5); 36.4% male). Results from structural equation modelling revealed that EE is positively associated with WL (β = 0.15, p = 0.001) and negatively associated with WF (β = -0.13, p = 0.001), also after accounting for potential confounding variables (demography, depressive symptoms, and lifetime diagnosis of burnout). Both effects are mediated by WLC (β = 0.18; p = 0.001 and β = 0.08; p = 0.001, respectively) highlighting the important role of WLC in employee health. In summary, WF may help to reduce burnout symptoms in employees, whereas WL may increase them. Study results suggest that both associations depend on WLC levels.
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.
This paper embeds the early political economy of Friedrich August von Hayek in the intellectual milieu of German ordoliberalism. The urgency during the 1930s and 1940s to stabilize the disintegrating societal orders is identified as a crucial driver behind the parallelisms between Hayek and the ordoliberals. Their shared theoretical position is that in such moments, liberty can thrive sustainably only after a framework of general and stable rules has been established. Hayek’s proximity to ordoliberalism was most explicitly discernible in The Road to Serfdom and at the founding meeting of the Mont Pèlerin Society in 1947, culminating in the shared politico-economic vision of the competitive order. The contextual nature of Hayek’s ordoliberalism surfaced in the years after The Constitution of Liberty when his focus shifted, along with the postwar intellectual and institutional stabilization of the West: from how stable orders enable liberty, to how liberty enables the evolution of orders.
Stefan Kolev zeichnet in seinem Beitrag die Geschichte und Bedeutung des schillernden Begriffs »Neoliberalismus« nach, welcher vielfach als Grund allen Übels gegen liberales Denken und Politik in Stellung gebracht wird. Kolev plädiert dafür, dass der Liberalismus sich immer wieder erneuern muss, also stetig neue Neoliberalismen benötigt.
The intention of the paper is to consider the role of technologies used to overcome the COVID-19’s challenges in higher education. On investigating, it has been found that the digital strategies utilizing innovation technologies help students to adapt to pandemic consequences. This study enlightens the various technologies that assist systems of healthcare and education in diverse aspects to outlive against COVID-19. Furthermore, the technological shift of world economy that happened during the pandemic and its influence in the society is discussed. Besides the considered innovation technologies, this paper also deals with changes that have taken place in education system of Kazakhstan in pandemic circumstances. Alongside our suggested solution for further educational process issues is also presented.
A detailed review of the literature is done on COVID-19, digital technologies in education, blended learning using appropriate keywords on SCOPUS, Springer, Science Direct, and Google Scholar. To get insights some relevant sites and blogs are also taken into account. We have identified technologies used in Kazakhstan that play an important role now.
There have been chosen exploratory and conclusive research design. Fifty-nine students provided qualitative responses; ninety-eight students and graduates participated in quantitative survey. The results of study has shown students’ increased awareness concerning blended learning.
The scientific novelty lies in the description of the experience gained by higher schools during the quarantine. We believe that in the future, blended learning should be used largely. The innovations in the learning process cover two areas. The first is related to software used. It is like creation of a virtual university that facilitates communication between students and teachers. The second area correlates with content, without which any innovation will fail.
En 1985 inició el Ministerio de Educación en Venezuela el Modelo de Atención Integral al Niño Sordo, un cambio de la práctica oralista a un modelo bilingüe en las escuelas de sordos. Eso implicaba eliminar la enseñanza del español hablado como objetivo principal e introducir la Lengua de Señas Venezolana (LSV) a las escuelas. Se desencadenó así un intenso período de cambios que marcó indeleblemente a la comunidad sorda. Aquí se aborda el Modelo desde la perspectiva de la planeación lingüística, describiendo sus objetivos y sus efectos sobre la adquisición, la estructura (el corpus) y el estatus de la LSV: La LSV y el español señado fueron reubicados en la diglosia existente hasta entonces; surgió una variante académica de la LSV y aumentó el número de usuarios de la LSV. El estudio se basó en el análisis cualitativo de entrevistas realizadas a cinco testigos de aquel proceso.
Hintergrund/Zielstellung: Aufgrund des gestiegenen Informationsbedürfnisses von Patienten wird für Ärzte ein eigener Webauftritt als Informationsmittler mit dem Ziel der Patientengewinnung und -bindung zunehmend bedeutsam. In der vorliegenden Studie wurde daher die Patientenorientierung der Internetauftritte niedergelassener Fachärzte für Orthopädie und/oder Unfallchirurgie in Sachsen untersucht.
Methode/Stichprobe: Alle Websites der im Arztregister der Kassenärztlichen Vereinigung Sachsen gelisteten Fachärzte für Orthopädie und/oder Unfallchirurgie wurden mithilfe einer standardisierten Checkliste analysiert.
Ergebnisse: Von allen untersuchten Fachärzten (n = 349) besaßen 140 (40,1 %) einen eigenen Internetauftritt. In der Arztpraxis durchgeführte diagnostische Methoden und Therapiemaßnahmen wurden auf je ca. 90,0 % der Websites genannt und auf ca. der Hälfte hiervon erklärt. Der Kontrast konnte auf 10 Websites angepasst werden. Eine Meinungsäußerung wurde den Patienten auf 28 Websites ermöglicht. Rechtlich verpflichtende Impressuminhalte wurden auf 45,0 % der Internetauftritte nicht hinreichend beachtet.
Diskussion/Schlussfolgerung: Die Ergebnisse weisen darauf hin, dass die Gestaltung der Internetauftritte sowie deren Informationsgehalt differieren und Verbesserungspotenziale existieren. Ein standardisierter Kriterienkatalog könnte ein einheitliches Qualitätsniveau gewährleisten und von den Ärzten als Handlungsempfehlung genutzt werden.
Analgesic drug use of recreational and competitive badminton players: Starting points for prevention
(2021)
Objectives: Evidence-based clinical guidelines play an important role in healthcare and can be a valuable source for quality indicators (QIs). However, the link between guidelines and QI is often neglected and methodological standards for the development of guideline-based QI are still lacking. The aim of this qualitative study was to get insights into experiences of international authors with developing and implementing guideline-based QI.
Setting: We conducted semistructured interviews via phone or skype (September 2017–February 2018) with guideline authors developing guideline-based QI.
Participants: 15 interview participants from eight organisations in six European and North American countries.
Methods: Organisations were selected using purposive sampling with a maximum variation of healthcare settings. From each organisation a clinician and a methodologist were asked to participate. An interview guide was developed based on the QI development steps according to the ‘Reporting standards for guideline-based performance measures’ by the Guidelines International Network. Interviews were analysed using qualitative content analysis with deductive and inductive categories.
Results: Interviewees deemed a programmatic approach, involvement of representative stakeholders with clinical and methodological knowledge and the connection to existing quality improvement strategies important factors for developing QI parallel to or after guideline development. Methodological training of the developing team and a shared understanding of the QI purpose were further seen conducive. Patient participation and direct patient relevance were inconsistently considered important, whereas a strong evidence base was seen essential. To assess measurement characteristics interviewees favoured piloting, but often missed implementation. Lack of measurability is still experienced a serious limitation, especially for qualitative aspects and individualised care.
Conclusion: Our results suggest that developing guideline-based QI can succeed either parallel to or following the guideline process with careful planning and instruction. Strategic partnerships seem key for implementation. Patient participation and relevance, measurement of qualitative aspects and piloting are areas for further development.
Trial registration number: German Clinical Trials Registry (DRKS00013006).
Hintergrund
Die Studienzeit ist eine Phase, in der die jungen Erwachsenen mit spezifischen Anforderungen konfrontiert werden. Studierende der Medizin gelten als besonders psychisch belastet. Untersuchungen, in denen sie diesbezüglich mit Studienfächern der gleichen Branche verglichen werden, sind jedoch rar.
Fragestellung
Ziel der Untersuchung war es, die psychische Gesundheit von Medizinstudierenden sowie von Gesundheits- und Pflegemanagementstudierenden zu untersuchen und zu vergleichen.
Material und Methoden
Untersucht wurden Studierende der Studiengänge Gesundheits- sowie Pflegemanagement (WHZ) und Medizinstudierende der (TU Dresden). Verschiedene Aspekte psychischer Gesundheit wurden mithilfe eines Online-Fragebogens erhoben. Dieser beinhaltete die Instrumente zur Erfassung der Prüfungsängstlichkeit (TAI-G-Kurzskala) und psychischen Belastung (BSI-18), sowie ein Item zur Ermittlung der subjektiv wahrgenommenen Studienbelastung. 258 Studierende nahmen an der Befragung teil.
Ergebnisse
Es konnten keine signifikanten Unterschiede hinsichtlich des Gesamtscores der Prüfungsängstlichkeit und der psychischen Belastung zwischen den Studierenden beider Studienfächer festgestellt werden. Dahingegen gaben Medizinstudierende an, dass sie im Vergleich zu Studierenden der anderen beiden Studienfächer eine signifikant höhere Studienbelastung wahrnehmen.
Schlussfolgerung
Die ermittelten Gesamtscores lagen teilweise über den Werten in vergleichbaren Studien. Die Studierenden sollten bereits präventiv unterstützt werden, um eigene Bewältigungsstrategien zu entwickeln. Nicht nur die Bereitstellung von Hilfen ist notwendig, sondern vielmehr das aktive Eingreifen mithilfe von gesundheitsfördernden Maßnahmen durch die Institution Hochschule, in die die Studierenden frühzeitig integriert werden sollten.
This paper provides a critical reading of Janek Wasserman’s The Marginal Revolutionaries: How Austrian Economists Fought the War of Ideas. Wasserman depicts the evolution of the Austrian School from the 1860s until today, a particularly illuminating narrative for the readers of this journal. The breadth of portrayed economists, their cultural embeddedness in Austrian and US contexts, and the complexity of configurations across the school’s generations create a rich and readable story. The last third of the book suffers from allegations about the ideological agenda and institutional power of the Austrian economists which sometimes lack sufficient substantiation. The paper indicates how both in their theorizing and in their political activities, the Austrian economists can be seen as reformers instead of revolutionaries, and as constitutionalists instead of anti-democrats. Despite these disagreements, Wasserman’s portrayals evoke largely fair and challenging impulses both to scholars working in the Austrian research program and to those interested in the Austrian School’s long history, regardless of one’s ideological positions.
Based on a real-world application in the semiconductor industry, this article models and discusses a hybrid flow shop problem with time dependencies and priority constraints. The analyzed problem considers a production where a large number of heterogeneous jobs are processed by a number of machines. The route that each job has to follow depends upon its type, and, in addition, some machines require that a number of jobs are combined in batches before starting their processing. The hybrid flow model is also subject to a global priority rule and a “same setup” rule. The primary goal of this study was to find a solution set (permutation of jobs) that minimizes the production makespan. While simulation models are frequently employed to model these time-dependent flow shop systems, an optimization component is needed in order to generate high-quality solution sets. In this study, a novel algorithm is proposed to deal with the complexity of the underlying system. Our algorithm combines biased-randomization techniques with a discrete-event heuristic, which allows us to model dependencies caused by batching and different paths of jobs efficiently in a near-natural way. As shown in a series of numerical experiments, the proposed simulation-optimization algorithm can find solutions that significantly outperform those provided by employing state-of-the-art simulation software.
The atomizing gas dynamics and the applied process energy have a significant influence on the produced particles. The melting process of the two wires can be influenced by current modulation. As for arc welding processes, more and more electronic and software-controlled machines are being used for arc spraying and will have replaced conventional power sources in the future. Due to the highly dynamic, fast regulating computing technology in the latest energy source, technology arcs can be operated with different current forms and types. The modern machines allow process-stable, reproducible variation of the particles and heat input into the substrate. Constant and pulsed current can be used as current forms. Usable current types are direct current (DC) and alternating current (AC). The electrical parameters must be analyzed to evaluate the process behavior. The consumable used is a wire-shaped iron-based alloy with a diameter of 1.6 mm. Relevant process parameters such as basic current Iground, pulse current Ipulse, pulse duration tpulse, impulse frequency fpulse, and alternating current frequency, fAC, are varied and recorded using appropriate measurement technology. The aim is to change the process performance and thereby the particle formation in a broad band. High-speed images are used to observe the arc and the deposition process. In addition, particle sizes are determined.