On the separation and recycling behaviour of textile reinforced concrete: an experimental study

This paper presents the results of recent experiments on the recyclability of the textile components in textile reinforced concrete (TRC). TRC as a multi-component system often contains organic ingredients such as carbon fibres and polymer impregnations. Consequently, the recycling of TRC is not trivial and has not yet been sufficiently clarified until now. In this study, an impregnated, bi-axially reinforced, and warp-knitted textiles made of carbon fibres was used in combination with a fine grained concrete. Flexural tests on TRC specimens containing recycled epoxy-impregnated carbon reinforcement were performed, whereby the recycling was simulated by a pre-treatment of the carbon fibre material in a jaw crusher. The results showed a pronounced decrease in flexural strength compared to untreated carbon reinforcement. Moreover, three different crushing methods were investigated with respect to their influence on the recovery of styrene-butadiene-rubber impregnated carbon textiles. Besides jaw crushing and impact milling, crushing with a hammer mill showed the best degree of purity but also caused the highest mechanical damage to the textile. The impact of material, structure of the composite and crushing methods on the separation behaviour could be deduced from the experiments.     

Ergonomic workplace design in the fast pick area

The aging society in many developed countries has made an ergonomic workplace design to an important topic among researchers and practitioners alike. We investigate the workplace design for order pickers that manually collect items from the shelves of a warehouse. Specifically, we treat the storage assignment, i.e., the placement of products in shelves of different height, and zoning, i.e., the partitioning of the storage space into areas assigned to separate pickers, in the fast pick area of a warehouse. A fast pick area unifies the most fast-moving items in a compact area, so that workers are relieved from unproductive travel, but face extraordinary ergonomic risks due to the frequent repetition of picking operations. Concerning the health of (aged) workers, it is crucial to reduce such risks. Thus, we define a combined ergonomic storage assignment and zoning problem with the objective of minimizing the maximum ergonomic burden among all workers. This problem is formalized, and two construction heuristics and a tabu search procedure are proposed. Our results show that neglecting ergonomic aspects and only focusing on picking performance leads to much higher ergonomic risks of the workforce.

     

Crystal structure and photocatalytic properties of titanate nanotubes prepared by chemical processing and subsequent annealing

Anatase TiO₂ nanoparticles were synthesized from sol–gel processing, and they were used as a precursor for titanate nanotubes (TNT) formation. TNT were synthesized under reflux heating of anatase TiO₂ in concentrated NaOH solution followed by repeated washing with distilled water and 0.1 M HCl. The nanotubular structure was preserved till 450 °C, above which nanorod formation started. The as-synthesized nanotubes were found to have mixed crystal structure of anatase and Na _x H_2?x Ti₃O₇·nH₂O (where 0 < x <  2), contrary to what has been reported before. The XRD peaks of titanate were slightly shifted to higher angles upon calcination along with prominent anatase peaks. Complete transformation to nanorods occurred at 600 °C and crystal structure was transformed to Na₂Ti₆O₁₃ and anatase. Sodium presence in TNT was confirmed by EDX, and Na–O and H–O–H along with Ti–OH vibrations were found by FTIR. Ti–OH/H–O–H vibrations were less prominent for samples calcined at 500 °C and above, which confirms structural water loss is associated with morphological change. The as-synthesized TNTs had a specific surface area of 157 m² g^?1, and it decreased by increasing calcination temperature. TNTs were applied to methylene blue aqueous solution to observe their decolorization capability under UV irradiation. The as-synthesized TNTs showed enhanced photocatalytic decolorization as compared to anatase titania nanoparticles due to presence of Ti–OH groups and higher specific surface area. The photocatalytic activity reduced when TNTs were annealed at high temperatures. The changes in the photocatalytic activity are related to the existence of hydroxyl groups in the structure, decrease in specific surface area of annealed nanotubes, change in morphology from nanotubes to nanorods, and bandgap shift to visible light when TNTs were calcined at higher temperatures.     

Enhanced processing of coatings on glass surfaces

In this contribution, basic technically usable interactions of atmospheric pressure plasmas (APP), laser irradiation and solids as well as a technique which combines such plasmas and laser irradiation are introduced. Two examples for plasma‐enhanced laser processing of coatings on glass surfaces are presented in more detail. First, APP‐assisted annealing of amorphous silicon layers is discussed. It is shown that the crystallised area is notably increased by assisting plasmas where the particular improvement factor depends on the particularly applied type of plasma. Second, the impact of assisting plasmas on laser removal of lacquers and varnishes from glass surfaces is presented. By introducing a plasma jet to the laser removal process, the laser energy required for cleaning or delamination is notably reduced.     

Strategic signaling through cloud service certifications: Comparing the relative importance of certifications’ assurances to companies and consumers

Cloud service certifications (CSCs) are assessed by practitioners to support strategic cloud adoption decisions with the aim to reduce information asymmetries. Both businesses and consumers scrutinize CSCs’ assurances as ex ante signals indicating a cloud provider’s future service quality. While some research has examined the aggregate effects of certifications on decision variables, recipients’ evaluations of certifications and their assurances before making IT-related decisions have received little attention. Furthermore, prior research has predominantly focused on privacy and security assurances in e-commerce certifications. Drawing on signaling theory, we propose that certifications are signals that recipients decompose into a set of fine-grained assurance signals that they weigh to evaluate certifications. We evaluate the responses of 113 company representatives and 317 consumers to a best-worst scaling survey to examine the relative importance these two groups attach to ten assurances from CSCs. Our results show that similar to other online contexts, security and privacy are important assurances, but additional assurances related to availability, the customer friendliness of contracts, and legal compliance are also demanded, particularly by companies. Privacy, security, and availability are most crucial to both companies and consumers, but their relative importance varies substantially between the two groups. Post-hoc subgroup analyses reveal significant differences in assurances’ relative importance for provider and user companies, adopter and non-adopter consumers as well as companies using different types of services and from different industries. Our findings indicate that recipients evaluate certifications as a bundle of signals with varying importance due to recipients’ characteristics and context. With this conceptualization, we contribute to an advanced understanding of the sense-making of certifications and lay out how it influences cloud service adoption theories. Our study has practical implications for certification authorities that design CSCs as well as for providing insights to cloud service providers on customers who draw on CSC assurances when making cloud service adoption decisions.     

Deep Fluids: A Generative Network for Parameterized Fluid Simulations

This paper presents a novel generative model to synthesize fluid simulations from a set of reduced parameters. A convolutional neural network is trained on a collection of discrete, parameterizable fluid simulation velocity fields. Due to the capability of deep learning architectures to learn representative features of the data, our generative model is able to accurately approximate the training data set, while providing plausible interpolated in‐betweens. The proposed generative model is optimized for fluids by a novel loss function that guarantees divergence‐free velocity fields at all times. In addition, we demonstrate that we can handle complex parameterizations in reduced spaces, and advance simulations in time by integrating in the latent space with a second network. Our method models a wide variety of fluid behaviors, thus enabling applications such as fast construction of simulations, interpolation of fluids with different parameters, time re‐sampling, latent space simulations, and compression of fluid simulation data. Reconstructed velocity fields are generated up to 700× faster than re‐simulating the data with the underlying CPU solver, while achieving compression rates of up to 1300×.     

Protein‐Enabled Synthesis of Monodisperse Titania Nanoparticles On and Within Polyelectrolyte Matrices

Here, the results of a study of the mechanism of bio‐enabled surface‐mediated titania nanoparticle synthesis with assistance of polyelectrolyte surfaces are reported. By applying atomic force microscopy, surface force spectroscopy, circular dichroism, and in situ attenuated total reflection Fourier‐transform infrared spectroscopy, structural changes of rSilC‐silaffin upon its adsorption to polyelectrolyte surfaces prior to and during titania nanoparticle growth are revealed. It is demonstrated that the adhesion of rSilC‐silaffin onto polyelectrolyte surfaces results in its reorganization from a random‐coil conformation in solution into a mixed secondary structure with both random coil and β‐sheet structures presented. Moreover, the protein forms a continuous molecularly thin layer with well‐defined monodisperse nanodomains of lateral dimensions below 20 nm. It is also shown that rSilC embedded inside the polylelectrolyte matrix preserves its titania formation activity. It is suggested that the surface‐mediated, bio‐enabled synthesis of nanostructured materials might be useful to develop general procedures for controlled growth of inorganic nanomaterials on reactive organic surfaces, which opens new perspectives in the design of tailored, in situ grown, hybrid inorganic–organic nanomaterials.     

New imide-copolymers with coronand structure

SUMMARY The Diels-Alder reaction of bis-(2-pyrone) 2 with various aliphatic and aromatic bismaleimides 1 in dilute solution was carried out to produce linear soluble copolymers with a coronand structure. NMR spectra and model reactions confirm the structure 4 (3). The polymers show weight losses at about 440°C determined by thermogravimetric analysis (Tab. 1). Received: 23 April 1998/Revised version: 8 June 1998/Accepted: 10 June 1998