Während eines Betriebsrundgangs mit dem Werkleiter zur Beurteilung der Ergonomie an Arbeitsplätzen verweilte dieser on einer lärmintensiven Anlage, zog sein Smartphone aus der Jackettasche und hielt es in Richtung der Maschine, um deren Schallpegel zu messen. Augenblicke später recherchierte er über die Suchfunktion des Gerätes nach zulässigen Grenzwerten. Am Ende des Rundgangs entspann sich eine Diskussion über die Aussagefähigkeit und Zuverlässigkeit Smartphone-gestützter Messungen von Arbeitsumweltfaktoren. Eine Studie am Institut für Produktionstechnik der Westsächsischen Hochschule Zwickau sollte klaren, ob es überhaupt noch des Einsatzes spezifischer Messtechnik bedarf. Das Ergebnis der Studie zeigt deutlich, dass sowohl die eingesetzte Hardware aktueller Smartphones und Tablets als auch die zur Verfügung stehen Programme bislang nicht den Ansprüchen einer Messung aus arbeitswissenschaftlicher Sicht entsprechen. Angesichts der Begeisterung vieler Gerätebesitzer in Kombination mit der Unkenntnis tatsächlicher Fähigkeiten solcher Apps ist es dringend notwendig, Aufklärungsarbeit zu leisten. Unabhängig von diesen Analyseergebnissen sollte die Chance betrachtet werden, dass durch zertifizierte messtechnische Erweiterungen von Smartphones eine engmaschigere und einfachere Überprüfung ergonomischer Arbeitsbedingungen möglich ist. Da es sich bei Smartphones vordergründig um Geräte zur Aufbereitung von Informationen handelt, verweist die Studie auf die Kopplung geeigneter Messsonden mit einem Smartphone. In dieser Kombination könnten Messsysteme zur Arbeitssystembeurteilung mit integrierter Anleitung entstehen, welche es vor allem ermöglichen, nicht nur korrekt zu messen, sondern die Ergebnisse auch richtig zu interpretieren und einzuordnen.
The science of ergonomics studies the conditions and effects of human labour in order to obtain rules for assessment and design. As working life changes, the general working conditions also change dynamically. The causes of such change processes are changes in working and lifestyle, human-technology-interaction, working time, as well as the demands on flexibility, mobility, decision-making skills and self-organization. The consequences of this development are a constant increase in the complexity of work-related requirements. The burdens associated with work can no longer be considered in a situational and detached way, as in many classical methods of work analysis, but should be taken into account in their holistic effect of mutual relations.
This article theoretically and empirically deals first with the question of whether the use of wearables provides support and assistance for the analysis of working conditions. Second it asks whether the application of wearables is a way to investigate complex stress conditions more effectively and whether it might supplement, substitute or further develop established and esteemed methods of work system analysis.
Die Arbeitswissenschaft untersucht die Bedingungen und Auswirkungen menschlicher Arbeit, um daraus Beurteilungs- und Gestaltungsregeln zu gewinnen. Mit dem Wandel des Arbeitslebens verändern sich auch die Rahmenbedingungen der Arbeit selbst dynamisch. Auslöser solcher Prozesse sind Veränderungen von Arbeits- und Lebensstil, der Mensch-Technik-Interaktion, der Arbeitszeit sowie den damit verbundenen Anforderungen an Flexibilität, Mobilität, Entscheidungsfähigkeit und Selbstorganisation. Als Folge dieser Entwicklung lässt sich ein Anstieg der Komplexität arbeitsbezogener Anforderungen feststellen. Eine korrekte Einordnung entsprechender Arbeitsbelastungen bedarf einer ganzheitlichen Betrachtung der Wirkung gegenseitiger Beziehungen. Damit schließen sich eine Vielzahl klassischer Verfahren der Arbeitsanalyse, die die einzelnen Sachverhalte situativ und losgelöst voneinander betrachten, aus.
Da eine Beurteilung komplexer Anforderungssituationen für den einzelnen Arbeitsanalytiker nur bedingt beherrschbar sein kann, setzt sich der Beitrag theoretisch und empirisch mit der Frage auseinander, ob durch den Einsatz von Wearables eine analytische Begleitung und Assistenz menschlicher Arbeit möglich ist. Es wird der Frage nachgegangen, ob mittels Wearables objektive und belastbare Aussagen zur Wirkung dynamischer Bündel unterschiedlicher Belastungen möglich sind, um anerkannte Verfahren der Arbeitssystemanalyse zu ergänzen, zu substituieren bzw. weiterzuentwickeln.
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.
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.
Lewis–Mogridge Points: A Nonarbitrary Method to Include Induced Traffic in Cost-Benefit Analyses
(2020)
We propose a new method to estimate benefits of road network improvements, which allows to include the induced demand without arbitrary assumptions. Instead of estimating induced demand (which is nontrivial and hardly possible in practice), we search for demand induction where initial benefits are mitigated to zero. Such approach allows to formulate a dual measure of benefit, covering both the potential benefits and the likelihood of consuming them by the induced traffic. We first estimate benefits of road network improvement assuming that traffic demand is fixed. Consequently, we find demand model configurations at which the benefits of the new investment become null, i.e., all the initial benefits are consumed by the traffic demand growth. We call such states of induced demand the Lewis–Mogridge points of the analysed improvement. We select the most probable of such points and use it to calculate the proposed novel indicator μ, for which the initial benefits (obtained under a fixed-demand assumption) are multiplied with a demand increase rate needed to consume them. We believe that such measure allows to include the critical phenomena of induced traffic and, at the same time, to overcome problems associated with reliable estimation of induced demand. As we illustrate with the case of two alternative road improvement schemes in Kraków, Poland, the proposed method allows to estimate maximal threshold of induced traffic and to select scenario more resilient to induced traffic.
Recent surveys and political research have shown that the acceptance of the political programmes of populist parties, such as the “Alternative für Deutschland (AfD)”, is relatively high amongst the population of the three eastern German federal states, especially in Saxony, where the AfD won nine of the 13 rural districts during the local elections in May 2019. Thus, it seems relevant to take a closer look at the persuasive discourse of a so-called populist party. In its public discourse, the AfD responds to the fears and concerns of those people who tend to use social media platforms to gain information when making political decisions. The aim of the article is to show which verbal and visual resources characterize the persuasive discourse of the AFD Saxony on their Facebook account. For this purpose, we propose a qualitative, multimodal analysis of selected entries which the party uploaded on its Facebook account between November 2018 and March 2019.
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.
Prussian blue (PB) layers were electrodeposited for the fabrication of Au/PB/Ag stacks to study the resistive switching effect. The PB layers were characterized by different techniques to prove the homogeneity, composition, and structure. Electrical measurements confirmed the bipolar switching behavior with at least 3 orders of magnitude in current and the effect persisting for the 200 cycles tested. The low resistance state follows the ohmic conduction with an activation energy of 0.2 eV.
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.
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.
Analgesic drug use of recreational and competitive badminton players: Starting points for prevention
(2021)
Traffic calming is introduced to minimise the negative results of motor vehicle use, for example, low safety level or quality of life, high noise and pollution. It can be implemented through the introduction of road infrastructure reducing the velocity and the traffic volume. In this paper, we studied how traffic-calming influences the traffic assignment. For the research, a traffic-calming measure of speed cushions on the Stachiewicza street in Krakow was taken. A method of extracting trajectories from aerial footage was shown, and it was used to build a model. For a given example, through driving characteristics research and microscopic modelling, volume–delay BPR functions were estimated—for a street with and without traffic calming. Later, a toy network of two roads of the same length, connecting the same origin and destination, was simulated using an equilibrium traffic assignment method. Simulations were conducted both with the use of PTV Vissim and Visum software and through individual calculations. According to the results of this paper, there was a difference in traffic volume according to the equilibrium traffic assignment in the aforementioned toy network as a function of total network traffic volume.
Effect of acoustic excitation on fiber-reinforced polypropylene and the influence on melt viscosity
(2021)
The paper describes a novel technological approach to influencing the rheological properties of thermoplastic materials exposed to acoustic energy. The flow behavior of polypropylene with different mass percentages of glass fibers is investigated in a parallel plate rheometer under high-frequency longitudinal excitation. The influence of oscillation frequency on the melt viscosity is explained by means of shear thinning criteria. The dependence of the oscillation shape using sinusoidal excitation on shear thinning as a function of different fiber reinforcement percentages is also investigated. A phenomenological view describes the mutually influencing parameters with regard to different material compositions and different excitation frequencies over the time course of the rheometric measurement. Interacting relationships are analyzed and discussed and the potential of the actuator system to influence the plastic melt is worked out. Based on this, a technological approach follows which describes the transfer of an oscillating mold surface to plastics processing methods, which, especially in the case of energy-intensive injection molding technology, leads to the expectation of possible resource efficiency in energy and material.
This paper presents numerical analysis of the discrete fundamental solution of the discrete Laplace operator on a rectangular lattice. Additionally, to provide estimates in interior and exterior domains, two different regularisations of the discrete fundamental solution are considered. Estimates for the absolute difference and lp‐estimates are constructed for both regularisations. Thus, this work extends the classical results in the discrete potential theory to the case of a rectangular lattice and serves as a basis for future convergence analysis of the method of discrete potentials on rectangular lattices.
Emotionale Kompetenzen und psychische Gesundheit: Eine Querschnittstudie in Gesundheitsberufen
(2021)
Hintergrund
Im Jahr 2020 waren 5,7 Mio. Menschen in Gesundheits- und Pflegeberufen tätig. Der Kontakt mit anderen Menschen ist in diesen Berufen Teil des Arbeitsauftrags und der Mensch ist der Arbeitsgegenstand.
Ziel der Arbeit
Das Ziel der Arbeit ist die Untersuchung der Auswirkung von psychischer Belastung (Arbeitsintensität, Spielräume), emotionaler Erschöpfung und emotionalen Kompetenzen (Regulation) auf das psychische Wohlbefinden bei Beschäftigten in Gesundheitsberufen.
Material und Methoden
Die Erhebung der Querschnittstudie von 624 Beschäftigten aus der Altenpflege und dem Rettungsdienst (72,5 % weiblich) erfolgte im Rahmen zweier Projekte zur betrieblichen Gesundheitsförderung. Zum Einsatz kamen standardisierte validierte Verfahren, welche mittels Korrelationsanalysen sowie einer hierarchischen Regressionsanalyse zur Vorhersage des psychischen Wohlbefindens ausgewertet wurden.
Ergebnisse
Hohe Arbeitsintensität, hohe Spielräume, hohe emotionale Erschöpfung und eine hohe emotionale Kompetenz (Regulation) tragen zur Aufklärung des psychischen Wohlbefindens bei (R2 = 33 %).
Schlussfolgerung
Anhand der Ergebnisse wird deutlich, dass neben dem Erleben von Arbeit und Gesundheit auch emotionale Kompetenzen einen Einfluss auf die psychische Gesundheit bei Beschäftigten in Gesundheitsberufen haben. Damit leistet die Studie einen wichtigen Beitrag für die Entwicklung von Maßnahmen des betrieblichen Gesundheitsmanagements in diesen Berufsgruppen.
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: Der überwiegende Teil der Patienten in Deutschland verstirbt entgegen ihres Wunsches nicht zu Hause. Eine Entscheidungshilfe für das notfallmedizinische Team kann nachfolgende Klinikeinweisungen von Patienten am Lebensende vermeiden.
Material und Methoden: Die Entscheidungshilfe Notarzt wurde im Rahmen des G-BA-Projektes AVENUE-Pal basierend auf einem Expertenkonsens mittels qualitativer und quantitativer Befragungen entwickelt. Sie stellt einen Teilaspekt des Gesamtprojektes dar.
Ergebnisse: Die EH Notarzt definiert 7 Ziele, die durch die Dimensionen „Information“, „Beratung“, „Unterstützung“, „Schulung“, „Anleitung“, „Übung“, „Kooperation“ und „Dokumentation“ erreicht werden sollen. Die EH Notarzt stellt eine Möglichkeit der Optimierung der notfallmedizinischen Behandlung von Patienten am Lebensende dar.
Diskussion: Die EH Notarzt ist eine Entwicklung zur Verbesserung der präklinischen Versorgung von Patienten am Lebensende und zur Vermeidung von Klinikeinweisungen am Lebensende. Derzeit ist die EH Notarzt ein theoretisches Hilfsmittel, welches in die praktische Anwendung überführt werden und weiterhin an die Notwendigkeiten der täglichen Patientenversorgung angepasst werden muss.
Introduction: In the spring of 2020, coronavirus disease 2019 posed a substantial challenge for countries and their healthcare systems. In Germany, over 70% of all cancer patients are treated in an outpatient setting, so gynecologic oncology practices are the guarantors of optimal patient care. We developed a survey to evaluate the management of gynecologic oncology patients.
Methods: The survey consisted of 38 questions and was sent to the members of the Berufsverband Niedergelassener Gynäkologischer Onkologen in Deutschland e.V. (BNGO), a professional association of gynecologic oncologists in the outpatient sector in Germany.
Results: The survey was completed by 54 out of 133 (41%) gynecologic oncologists from 14 out of 15 (93%) federal states where the BNGO is represented. Facing the pandemic, popular measures were mask requirements (100%), restriction of access to practices (94%), increased number of disinfectant dispensers (85%), installment of panes of acrylic glass (76%), or spatial alterations (67%). For most patients the pandemic had no influence on prioritization of therapies (82%) or prescribed systemic treatments (87%). Despite an increase in perceived psychological burden among the staff (72%), 85% (45/54) of the practices were not offered any additional psychological support.
Discussion and Conclusion: As most cancer patients in Germany are treated in an outpatient setting, a suitable reaction of oncology centers to the new circumstances was crucial to secure optimal treatment and patient care. Nevertheless, the low prioritization of mental health or distress of healthcare workers poses a serious threat to the maintenance of optimal medical care in further waves of the pandemic.
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.
Routing games over time are widely studied due to various applications, e.g., transportation, road and air traffic control, logistic in production systems, communication networks like the internet, and financial flows. In this article, we present a new competitive packet routing game with edge priorities motivated by traffic and transportation. In this model a set of selfishly acting players travels through the network over time. If the number of players who want to enter an edge at the same time exceeds the inflow capacity of this edge, then edge priorities with respect to the preceding edge are used to resolve these conflicts, which is similar to right-of-way rules in traffic. We analyze the efficiency of pure Nash equilibria, present an efficient algorithm for computing equilibria in symmetric games, and show that it is NP-hard to decide whether a Nash equilibrium exists in an asymmetric game. Furthermore, we address the problem of constructing optimal priorities.
Analysis of a Film Forming Process through Coupled Image Correlation and Infrared Thermography
(2022)
The aim of the present investigation was to determine the dependence of the material and process parameters of the bending process of thermoplastic films. In this context, parameter combinations leading to high resulting forming ratios were identified. To measure the relevant parameters within the hot bending process, a coupled evaluation of infrared thermography (IRT) and deformation measurement using digital image correlation (DIC) was performed. The coupled measurement enables the identification of the actual mechanically stressed bending area of the film as a result of the bending process. This allows for the specification of the local forming temperatures required for the desired forming ratios. Furthermore, the mechanical and thermal strain along the defined measuring sections and their deviation in individual tests as well as the effect of thermal strain on process control on a larger scale were determined. Based on the results, a process window was defined for the film materials investigated, which will serve as a starting point for future efforts to develop a continuous manufacturing process.
In this work, a new method for selecting suitable materials is presented. This method has a high potential for a variety of engineering applications, such as the design of sound-absorbing and vibration-loaded structures, where a large number of different requirements have to be met. The method is based on the derivation of functional dependencies of selected material parameters. These dependencies can be used in parameter studies to consider parameter combinations that lie in the range of real existing and targeted material groups. This allows the parameter space to be reduced, the calculation to be accelerated, and suitable materials to be (pre-)selected for the respective application, which contributes to a more target-oriented design. The method is applied to the example of a plate resonator. For this purpose, a semi-analytical model is implemented to calculate the transmission loss as well as the reflected and dissipated sound power of plate silencers, taking into account the influence of flow velocity and fluid temperature on the performance of plate silencers.
The removal of bacterial infections within the root canal system is still a challenge. Therefore, the cleansing effect of established and new irrigation-protocols (IP) containing silver diamine fluoride (SDF) 3.8% on the whole root canal system was analyzed using quantitative PCR (qPCR) and 4′,6-diamidino-phenylindole-(DAPI)-staining. Extracted human premolars were instrumented up to F2 (ProTaper Gold) under NaCl 0.9% irrigation and incubated with Enterococcus faecalis for 42 days. Subsequently, different ultrasonically agitated IP were applied to the roots: control (no irrigation), 1. NaOCl 3%, EDTA 20%, CHX 2%, 2. NaOCl 3%, EDTA 20%, 3. NaOCl 3%, EDTA 20%, SDF 3.8%, 4. SDF 3.8%, and 5. NaCl 0.9%. One half of the root was investigated fluorescent-microscopically with DAPI. The other half was grinded in a cryogenic mill and the bacterial DNA was quantified with qPCR. The qPCR results showed a statistically significant reduction of bacteria after the application of IP 1, 2, and 3 compared to the control group. While IP 4 lead to a bacterial reduction which was not significant, IP 5 showed no reduction. These data corresponded with DAPI staining. With qPCR a new molecular-biological method for the investigation of the complete root canal system was implemented. The novel IP 3 had an equally good cleansing effect as the already established IP.
Structures made of the thermoplastic polymer polyether ether ketone (PEEK) are widely used in dynamically-loaded applications due to their high-temperature resistance and high mechanical properties. To design these dynamic applications, in addition to the well-known stiffness and strength properties the vibration-damping properties at the given frequencies are required. Depending on the application, frequencies from a few hertz to the ultrasonic range are of interest here. To characterize the frequency-dependent behavior, an experimental approach was chosen and applied to a sample polymer PEEK. The test setup consists of a piezoelectrically driven base excitation of the polymeric specimen and the non-contact measurement of the velocity as well as the surface temperature. The beam’s bending vibrations were analyzed by means of the Timoshenko theory to determine the polymer’s storage modulus. The mechanical loss factor was calculated using the half-power bandwidth method. For PEEK and a considered frequency range of 1 kHz to 16 kHz, a storage modulus between 3.9 GPa and 4.2 GPa and a loss factor between 9 × 10−3 and 17 × 10−3 were determined. For the used experimental parameters, the resulting mechanical properties were not essentially influenced by the amplitude of excitation, the duration of excitation, or thermal degrad.ation due to self-heating, but rather slightly by the clamping force within the fixation area.
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.
Der General
(2022)
Sodium iron hexacyanoferrate (NaFeHCF) films were electrodeposited on Au/Cr/Si for the study of growth behavior and physical properties. The NaFeHCF films were studied by different analytical methods to prove the chemical composition, morphology and crystal structure. The grains of the film grow with a cubic structure with an average lattice parameter of 10.10 Å and the preferential growth direction along the [111] direction of the cubic cell. The films show a repeatable bipolar resistive switching behavior accompanied by high current changes (up to a factor of ~105). The different resistive states in the materials are dominated by ohmic conduction.
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.
Introduction
(2022)
A novel approach to consider triaxial tensile stresses within the framework of a failure criterion
(2022)
For use in micromechanical simulations of continuous fiber reinforced polymers, a more general form of the paraboloid failure criterion by Stassi‐D'Alia for matrix failure was developed with explicit consideration of the hydrostatic tension strength. Regarding polymers, limits for hydrostatic tensile strength based on isotropic linear elasticity could be derived. The comparison of the newly developed extended paraboloid criterion with experimental data for yielding as well as for material separation (fracture) shows good agreement.
This paper presents an analytical method for determining the bending stresses and deformations in prismatic, noncircular profile shafts with trochoidal cross sections. The so-called higher trochoids can be used as form-fit shaft-hub connections. Hybrid (mixed) higher trochoids (M-profiles) were developed for the special application as a profile contour for the form-fit shaft and hub connections in an earlier work by the author. M-profiles combine the advantages of the two standardised polygonal and spline contours, which are used as shaft-hub connections for the transmission of high torques. In this study, the geometric and mechanical properties of the higher hybrid trochoids were investigated using complex functions to simplify the calculations. The pure bending stress and shaft deflection were determined for M-profiles using bending theory based on the theory of mathematical elasticity. The loading cases consisted of static and rotating bends. Analytical, numerical, and experimental results agreed well. The calculation formulas developed in this work enable reliable and low-cost dimensioning with regard to the stresses and elastic deformations of profile shafts subjected to bending loads.