Stability of thin liquid films and sessile droplets under confinement

The stability of nonvolatile thin liquid films and of sessile droplets is strongly affected by finite size effects. We analyze their stability within the framework of density functional theory using the sharp kink approximation, i.e., on the basis of an effective interface Hamiltonian. We show that finite size effects suppress spinodal dewetting of films because it is driven by a long-wavelength instability. Therefore nonvolatile films are stable if the substrate area is too small. Similarly, nonvolatile droplets connected to a wetting film become unstable if the substrate area is too large. This instability of a nonvolatile sessile droplet turns out to be equivalent to the instability of a volatile drop which can attain chemical equilibrium with its vapor.Comment: 14 pages, 13 figure

Improving the inner surface state of thick-walled tubes by heat treatments with internal quenching considering a simulation based optimization

Internal Quenching is an innovative heat treatment method for difficult to access component sections. Especially, the microstructure, as well as the residual stress state at inner surfaces, of thick-walled tubes can be adjusted with the presented flexible heat treatment process. Based on multiphysical FE-models of two different steels, a simulative optimization study, considering different internal quenching strategies, was performed in order to find the optimal cooling conditions. The focus hereby was on the adjustment of a martensitic inner surface with high compressive residual stresses. The simulatively determined optimal cooling strategies were carried out experimentally and analyzed. A good agreement of the resulting hardness and residual stresses was achieved, validating the presented Fe-model of the Internal Quenching process. The shown results also indicate that the arising inner surface state is very sensitive to the transformation behavior of the used steel. Furthermore, the presented study shows that a preliminary simulative consideration of the heat treatment process helps to evaluate significant effects, reducing the experimental effort and time

Vocational Education and Employment: Explaining Cohort Variations in Life Course Patterns

A stylized finding on returns to vocational education is that vocational compared to general education generates a differential life course pattern of employability: while vocational education guarantees smooth transitions into the labour market and thus generates initial advantages, these erode with increasing age, leading to late-life reversals in employment chances. We contribute to this research by assessing cohort variations in life-cycle patterns and distinguishing two explanations for late-life reversals in employment chances. The adaptability argument states that this phenomenon is due to the lower adaptability and occupational flexibility of those with vocational education. In contrast, the health argument states that vocational education leads to physically more demanding occupations, faster health deterioration, and, thus, lower employability in later life. Using data from the German Socio-Economic Panel, we employ non-parametric state probability analysis to assess cohort variations in employment patterns, and mediation analysis to assess how much of the late-life reversal of employment patterns is due to a faster health deterioration among the vocationally educated. Results show that the early life advantage of vocational education increases across cohorts. Furthermore, those with vocational education exhibit faster health deterioration, and a small part of the late-life employment disadvantage of this group works through lower levels of health after midlife

A Systematic Literature Review of Blockchain-Based Traceability Solutions

Blockchain technology shows great potential in providing object-related end-to-end traceability in complex multitiered supply networks. However, the first systematic literature reviews indicate the immaturity of current blockchain-based solutions and highlight difficulties in assessing their object traceability capabilities. Therefore, this paper provides a systematic literature review of blockchain-based traceability solutions and analyses their object-related mapping capabilities. As the systematic literature reveals, the vast majority of the identified traceability solutions deal with low-complexity architectures without the ability to map objects' compositional changes. Here, food and medical supply chains represent the most dominant domains. Supply chains in the automotive and manufacturing domain place the highest requirements for mapping object-related supply chain events. In this context, solutions incorporating the tokenisation of objects show the most advanced object-related mapping capabilities. However, the identified advanced solutions show limitations regarding their ability to map object deletions, aggregations, and disaggregations. Furthermore, current blockchain-based traceability solutions provide only limited validations based on industrial case studies

People work with People. School inspection and the hope of the unforced force of "better evidence"

Im Konzept der evidenzbasierten Steuerung drückt sich einmal mehr die Hoffnung auf eine intentionale Gestaltbarkeit des Schulsystems aus. Die dezentrale Steuerung über empirische Evidenzen verspricht eine "Schulentwicklung durch Einsicht" und damit eine Rationalisierung des Steuerungsprozesses: Inspektoren und Inspektorinnen sowie schulische Akteure sollen sich "auf Augenhöhe" begegnen, und Schulentwicklung soll durch die rationale Auseinandersetzung mit "objektiven Fakten" vorangetrieben werden. Fraglich ist jedoch, welcher Logik die evidenzbasierte Steuerung in der Praxis tatsächlich folgt. Am Beispiel der Schulinspektion wird gezeigt, dass der Evidenzbegriff auf der Ebene der Steuerungsprogrammatik sehr unterschiedlich ausgestaltet wird. Aus rekonstruktiver Perspektive zeigt sich, dass die evidenzbasierte Steuerung maßgeblich davon abhängt, inwieweit die durch die Schulinspektion erzeugten Evidenzen glaubhaft gemacht werden können. Damit ist nicht die Generierung, sondern die Vermittlung von Evidenzen die zentrale Strukturproblematik der Schulinspektionspraxis. (DIPF/Orig.)The concept of evidence-based steering expresses once more the hope of an intentional structuring of the school system. Decentralised steering via empirical evidence promises "school development through reason" and thereby a rationalisation of the process of steering. Inspectors and actors at school shall meet each other "at eye level", and school development shall be promoted by a rational dispute of the "objective facts". However, the question is which logical structure this conception follows. With school inspection as example, it is demonstrated that the notion of evidence is formulated very differently at the level of steering objectives. From a reconstructive perspective it becomes apparent that evidence-based steering crucially depends on the extent to which evidence, generated via school inspection, can be made credible. Consequently, not the generation of evidence but rather the conveyance of evidence is the central structural problem of the practice of school inspection. (DIPF/Orig.

Short-time induction heat treatment of high speed steel AISI M2: Laboratory proof of concept and application-related component tests

High-speed steels (HSS) such as AISI M2 are generally used for cutting and forming tools or broaches with the highest demands on load bearability and hot-hardness. The requirements for high-speed steels are, on the one hand, extremely high hardnesses of over 800–900 HV and, on the other hand, the thermal stability of the microstructure up to 500 °C. This combination is achieved by complex precipitation-hardenable iron-based alloys. Common heat treatment practices for high-speed steels use salt baths or vacuum ovens, which are energetically unfavorable and require subsequent cleaning. The study consists of short-time hardening and short-time tempering on a laboratory scale by means of dilatometry and thereupon an implementation in an industrial induction hardening machine. The laboratory scale experiments demonstrate the feasibility of bringing sufficient alloying elements into solution by means of several heat treatment cycles despite short holding times of 1 s and less. Combined tests of short time hardening and tempering show a hardness of up to 850 HV10 that are competitive with the conventional heat treatment route. First attempts to transfer the process to an industrial setup exhibit some peculiarities in the process control, but reveal promising results with a surface hardness of up to 750 HV10

Opportunities And Challenges Of The Asset Administration Shell For Holistic Traceability In Supply Chain Management

Due to changing regulatory environments, evolving sustainability requirements, and the need to perform effective supply chain risk management, traceability systems have become an increasingly important aspect of supply chain management. However, globalized, interconnected supply chains require a dynamic mapping of direct and indirect relationships between companies and assets, driving traceability systems' complexity. Here, the standardization of data formats provides an essential aspect to facilitate asset-related information sharing across companies. In this regard, the Asset Administration Shell is available as a holistic standardized digital representation of an asset. The representation of an asset via an Administration Shell includes data ensuring a clear identification of the Administration Shell and its assets as well as data describing aspects of the asset's technical functionality in so-called submodels. Based on current literature and available prototypical concepts, this paper identifies the opportunities and challenges of the Asset Administration Shell when aiming to map interconnected multi-tier supply chains holistically and contextualizes their role in achieving holistic supply chain traceability

Review of Blockchain-based Tokenization Solutions for Assets in Supply Chains

Recently, blockchain-based tokens have earned an important role in fields such as the art market or online gaming. First approaches exist, which adopt the potentials of blockchain tokens in supply chain management to increase transparency, visibility, automation, and disintermediation of supply chains. In context, the tokenization of assets in supply chains refers to the practice of creating virtual representations of physical assets on the blockchain. Solutions in supply chain management based on the tokenization of assets vary in terms of application objectives, token types, asset characteristics, as well as the complexities of supply chain events to be mapped on the blockchain. Currently, however, no review exists that summarizes the characteristics of blockchain-based tokens and their scope of applications. This paper provides a clear terminological distinction of existing blockchain token types and therefore distinguishes between fungible tokens, non-fungible tokens, smart non-fungible tokens, and dynamic smart non-fungible tokens. Subsequently, the token types are classified regarding their traceability, modifiability, and authorization to evaluate suitability for mapping assets in supply chains. Given the potential of blockchain in supply chain management, the results of the review serve as a foundation for a practical guide supporting the selection process of suitable token types for industrial applications

Novel form-flexible handling and joining tool for automated preforming

The production rates of carbon fiber reinforced plastic (CFRP) parts are rising constantly which in turn drives research to bring a higher level of automation to the manufacturing processes of CFRP. Resin transfer molding (RTM), which is seen as a production method for high volumes, has been accelerated to a high degree. However, complex net-shape preforms are necessary for this process, which are widely manually manufactured. To face these challenges a new concept for the manufacturing of carbon fiber preforms with a form-flexible gripping, draping and joining end-effector is presented and discussed. Furthermore, this paper investigates the application of this concept, describes the initial build-up of a demonstrator, focusing on material selection and heating technology, and discusses test results with the prototype. This prototype already validates the feasibility of the proposed concept on the basis of a generic preform geometry. After a summary, this paper discusses future in-depth research concerning the concept and its application in more complex geometries. © 2015 by De Gruyter 2015