Comparison of type-based and alias-based component recognition for embedded systems software

Component-based software engineering has found broad acceptance within the embedded systems community over the last years. However, to fully exploit its potential in terms of reusability and cost-efficiency, existing code-bases have to be refactored in a component-based way. To support refactorization, static analysis techniques can be used to identify components within coarse-grained layered or even monolithic legacy software for embedded systems. We present an approach for semi-automatic extraction of components from automotive software and compare two different versions, one type-based component-recognition analysis of linear complexity with a more precise version based on a points-to analysis of almost linear algorithmic complexity. Both analyses are applied to an industrial implementation of an automotive communication stack. Each analysis is evaluated with two sets of additional manually created annotations of distinct size and precision. Thus, both analyses are fully evaluated in terms of execution-time, memory consumption and analysis precision, and its impact on the number of recognized components. We show that the analysis with higher precision allows the use of a smaller user-provided filter set and obtain a proper component recognition.     

Practical experiences of applying source-level WCET flow analysis to industrial code

Code-level timing analysis, such as worst-case execution time (WCET) analysis, usually takes place at the binary level. However, many program properties that are important for the analysis, such as constraints on possible program flows, are easier to derive at the source code level since this code contains much more information. Therefore, various source-level analyses can provide valuable support for timing analysis. However, source-level analysis is not always smoothly applicable in industrial settings. In this paper, we report on the experiences of applying source-level analysis to industrial code in the ALL-TIMES project: the promises, the pitfalls, and the workarounds that were developed. We also discuss various approaches to how the difficulties that were encountered can be tackled.     

Chemical modification of preceramic polymers: Their reactions with transition metal complexes and transition metal powders

Conclusions This research has demonstrated that a variety of chemistries can be carried out with preceramic polymers that in general are characterized by the presence of an abundance of reactive functional groups. Such chemistries can serve to upgrade a given preceramic polymer by catalytic or stoichiometric processes; they can be used to from new and useful hybrid polymers from the original preceramic polymer, as shown in the present work and also in some of our previously published work; they can, by their pyrolysis in the presence of metal powders, act as chemical reagents that deliver the elements of interest for reaction with the metal to give useful ceramics. Thus the preparation of a preceramic polymer is not the end of the chemistry in the monomer-to-polymer-to-ceramic conversion, but rather it presents many possibilities for further chemistry.     

On the mechanical modeling of functionally graded interfacial zone with a Griffith crack: plane deformation

A new multi-layered model is developed for a functionally graded interfacial zone between two dissimilar elastic solids based on the fact that an arbitrary curve can be approached by a continuous but piecewise linear curve. The interfacial zone with both Young’s modulus and Poisson’s ratio varying continuously in an arbitrary manner is divided into multiple layers with the material properties varying linearly in each sub-layer and continuous at the interfaces between sub-layers. With this new model, we analyze the problem of a Griffith crack in the interfacial zone under plane stress-state deformation. The transfer matrix method and Fourier integral transform technique are used to reduce the mixed boundary-value problem to a set of Cauchy singular integral equations. The stress intensity factors are calculated. The paper compares the new model to other existing models and discusses its advantages.     

Creating three-dimensional (3D) fiber networks with out-of-plane auxetic behavior over large deformations

Fiber networks with out-of-plane auxetic behavior have been sporadically investigated. One of the major challenges is to design such materials with giant negative Poisson’s ratio over large deformations. Here in, we report a systematic investigation to create three-dimensional (3D) fiber networks in the form of needlepunched nonwoven materials with out-of-plane auxetic behavior over large deformations via theoretical modeling and extensive set of experiments. The experimental matrix has encapsulated the key parameters of the needlepunching nonwoven process. Under uniaxial tensile loading, the anisotropy coupled with local fiber densification in networks has yielded large negative Poisson’s ratio (up to ?5.7) specifically in the preferential direction. The in-plane and out-of-plane Poisson’s ratios of fiber networks have been predicted and, subsequently, compared with the experimental results. Fiber orientation was found to be a core parameter that modulated the in-plane Poisson’s ratio of fiber networks. A parametric analysis has revealed the interplay between the anisotropy of the fiber network and the out-of-plane Poisson’s ratio based upon constant volume consideration.     

Biologically Inspired Scaffolds for Heart Valve Tissue Engineering via Melt Electrowriting

Heart valves are characterized to be highly flexible yet tough, and exhibit complex deformation characteristics such as nonlinearity, anisotropy, and viscoelasticity, which are, at best, only partially recapitulated in scaffolds for heart valve tissue engineering (HVTE). These biomechanical features are dictated by the structural properties and microarchitecture of the major tissue constituents, in particular collagen fibers. In this study, the unique capabilities of melt electrowriting (MEW) are exploited to create functional scaffolds with highly controlled fibrous microarchitectures mimicking the wavy nature of the collagen fibers and their load‐dependent recruitment. Scaffolds with precisely‐defined serpentine architectures reproduce the J‐shaped strain stiffening, anisotropic and viscoelastic behavior of native heart valve leaflets, as demonstrated by quasistatic and dynamic mechanical characterization. They also support the growth of human vascular smooth muscle cells seeded both directly or encapsulated in fibrin, and promote the deposition of valvular extracellular matrix components. Finally, proof‐of‐principle MEW trileaflet valves display excellent acute hydrodynamic performance under aortic physiological conditions in a custom‐made flow loop. The convergence of MEW and a biomimetic design approach enables a new paradigm for the manufacturing of scaffolds with highly controlled microarchitectures, biocompatibility, and stringent nonlinear and anisotropic mechanical properties required for HVTE.     

Solid and timber construction in residential buildings / Massiv‐ und Holzbau bei Wohngebäuden

In the context of a comprehensive analysis of the current situation in Germany’s residential sector as regards construction costs and developments in these, the Arbeitsgemeinschaft für zeitgemäßes Bauen e.V. (ARGE) undertook a specific study to investigate the use of the main materials for building walls (using both solid and timber construction methods) in residential buildings. In order to obtain comparable data, two buildings typical of the residential sector were modelled: an apartment block and a detached house. These reflect the current building situation in Germany. It should be noted that for both multi‐storey buildings and detached homes, if we look at the median cost, it is more economical to use masonry for the basic structure than timber. The cost advantage of the solid construction method over the timber method for detached houses is 4 %, and the median advantage for apartment blocks is between 4.7 and 6 %. The studies we used in our assessment of the sustainability of the building materials used (for example from TU Darmstadt) conclude that both construction methods (solid and timber) are comparable in terms of the ‘ecological balance sheet’ results achieved over their entire life cycles and occupancy phases.     

Multistakeholder recommendation: Survey and research directions

Recommender systems provide personalized information access to users of Internet services from social networks to e-commerce to media and entertainment. As is appropriate for research in a field with a focus on personalization, academic studies of recommender systems have largely concentrated on optimizing for user experience when designing, implementing and evaluating their algorithms and systems. However, this concentration on the user has meant that the field has lacked a systematic exploration of other aspects of recommender system outcomes. A user-centric approach limits the ability to incorporate system objectives, such as fairness, balance, and profitability, and obscures concerns that might come from other stakeholders, such as the providers or sellers of items being recommended. Multistakeholder recommendation has emerged as a unifying framework for describing and understanding recommendation settings where the end user is not the sole focus. This article outlines the multistakeholder perspective on recommendation, highlighting example research areas and discussing important issues, open questions, and prospective research directions.

     

Topology optimization of energy absorbers under crashworthiness using modified hybrid cellular automata (MHCA) algorithm

Structural and Multidisciplinary Optimization - Meta-heuristic and hyperheuristic algorithms are milestones that make the topology optimization practical for dynamic and nonlinear problems....