Mechanical properties of concrete containing phase-change material

This study aimed to investigate the mechanical properties of concrete containing solid–liquid phase-change material (PCM) and focused on two key factors. First, a systematic study on the mechanical performance of PCM-modified concretes was conducted, including compressive, elastic modulus, and shrinkage tests. Second, because PCM provides high latent heat during the solid–liquid phase change, the effects of the solid phase and liquid phase on the mechanical properties of concrete were also explored. Results of this study showed that the solid–liquid phase of PCM affected the mechanical properties of concrete. For example, the compressive strength of 10% PCM concrete in solid phase (23 °C) and liquid phase (40 °C) at 28 days was 29.30 and 19.57 MPa, respectively. In addition, with increasing PCM content, the mechanical properties were degraded. For example, 10, 20, and 30% of PCM content lowered the compressive strength by 35.4, 58.4, and 74.3%, respectively. Therefore, concrete with PCM may not be suitable for structural elements. However, PCM is an important solution for optimizing energy consumption in modern buildings. It can absorb or emit large amounts of heat to store or release thermal energy. These properties can be used to control building temperatures resulting in energy saving and carbon reduction.     

On pebble automata for data languages with decidable emptiness problem

In this paper we study a subclass of pebble automata (PA) for data languages for which the emptiness problem is decidable. Namely, we show that the emptiness problem for weak 2-pebble automata is decidable, while the same problem for weak 3-pebble automata is undecidable. We also introduce the so-called top view weak PA. Roughly speaking, top view weak PA are weak PA where the equality test is performed only between the data values seen by the two most recently placed pebbles. The emptiness problem for this model is still decidable. It is also robust: alternating, non-deterministic and deterministic top view weak PA have the same recognition power; and are strong enough to accept all data languages expressible in Linear Temporal Logic with the future-time operators, augmented with one register freeze quantifier.     

A method for evaluating rigor and industrial relevance of technology evaluations

One of the main goals of an applied research field such as software engineering is the transfer and widespread use of research results in industry. To impact industry, researchers developing technologies in academia need to provide tangible evidence of the advantages of using them. This can be done trough step-wise validation, enabling researchers to gradually test and evaluate technologies to finally try them in real settings with real users and applications. The evidence obtained, together with detailed information on how the validation was conducted, offers rich decision support material for industry practitioners seeking to adopt new technologies and researchers looking for an empirical basis on which to build new or refined technologies. This paper presents model for evaluating the rigor and industrial relevance of technology evaluations in software engineering. The model is applied and validated in a comprehensive systematic literature review of evaluations of requirements engineering technologies published in software engineering journals. The aim is to show the applicability of the model and to characterize how evaluations are carried out and reported to evaluate the state-of-research. The review shows that the model can be applied to characterize evaluations in requirements engineering. The findings from applying the model also show that the majority of technology evaluations in requirements engineering lack both industrial relevance and rigor. In addition, the research field does not show any improvements in terms of industrial relevance over time.     

Contact type dependency of texture classification in a whiskered mobile robot

Actuated artificial whiskers modeled on rat macrovibrissae can provide effective tactile sensor systems for autonomous robots. This article focuses on texture classification using artificial whiskers and addresses a limitation of previous studies, namely, their use of whisker deflection signals obtained under relatively constrained experimental conditions. Here we consider the classification of signals obtained from a whiskered robot required to explore different surface textures from a range of orientations and distances. This procedure resulted in a variety of deflection signals for any given texture. Using a standard Gaussian classifier we show, using both hand-picked features and ones derived from studies of rat vibrissal processing, that a robust rough-smooth discrimination is achievable without any knowledge of how the whisker interacts with the investigated object. On the other hand, finer discriminations appear to require knowledge of the target’s relative position and/or of the manner in which the whisker contact its surface. Electronic Supplementary Material  The online version of this article () contains supplementary material, which is available to authorized users.