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Nanomaterials have been applied for the modification of cement-based materials with a low-dosage addition in recent years. Graphene oxide (GO) has been studied in many papers for use in cement-based materials with properties of a two-dimensional sheet-like structure, its extraordinary mechanical properties, high aspect ratio and hydrophilicity. To study the effects of graphene oxide on the hydration of tricalcium silicate, the hydration heat, hydration products and micro-structure of a C₃S-GO hydration system were studied in this paper. The results showed that GO increases the hydration heat by promoting the hydration rate of C₃S, though the GO could not react with the C3S hydration products (such as the calcium hydroxide and C-S-H gel produced by the C₃S hydration). It was found that the addition of GO changes the crystallite size of the hydration products through observing the SEM image. The GO modified the morphology of the C₃S hydration products and led to a more compacter structure.

For a hybrid stochastic system, most existing feedback controllers need to observe modes at continuous times, which is feasible when the system's mode is observable and does not incur any cost. However, in most cases, the mode is not readily apparent, and identifying it always incurs a certain expense. Therefore, in order to reduce control costs, when designing a feedback controller, both the state and the mode should be observed at discrete moments. This paper introduces an intermittent feedback controller for stabilizing an unstable hybrid stochastic system through discrete delayed observations of state and mode. By utilizing M-matrix theory, intermittent control approach, and the comparison principle, we propose sufficient conditions for the stabilization theory of hybrid stochastic systems. An illustrative example is taken to validate the proposed theory. [ABSTRACT FROM AUTHOR]

Recycling aluminosilicate-based solid wastes is imperative to realize the sustainable development of constructions. By using alkali activation technology, aluminosilicate-based solid wastes, such as furnace slag, fly ash, red mud, and most of the bio-ashes, can be turned into alternative binder materials to Portland cement to reduce the carbon footprint of the construction and maintenance activities of concrete structures. In this paper, the chemistry involved in the formation of alkali-activated materials (AAMs) and the influential factors of their properties are briefly reviewed. The commonly used methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG), nuclear magnetic resonance spectroscopy (NMR), and X-ray pair distribution function technology, to characterize the microstructure of AAMs are introduced. Typical characterization results of AAMs are shown and the limitations of each method are discussed. The main challenges, such as shrinkage, creep, efflorescence, carbonation, alkali–silica reaction, and chloride ingress, to conquer for a wider application of AAMs are reviewed. It is shown that several performances of AAMs under certain circumstances seem to be less satisfactory than traditional portland cement systems. Existing strategies to improve these performances are reviewed, and recommendations for future studies are given. [ABSTRACT FROM AUTHOR]

Summary: This article investigates the dissipative fault detection (FD) problem for time‐delay nonlinear Markov jump systems with measurement outliers in the case of partially unknown transition probabilities. The stochastic communication protocol is utilized to save network bandwidth, where the scheduling model is described via a Markov chain. An outlier‐resistant FD filter is constructed with the help of adaptive saturation function technology. The sufficient conditions are derived to ensure that the FD system satisfies the stochastic stability and stochastic strict dissipativity. In addition, an FD filter without saturation constraint is also designed to compare with the outlier‐resistant FD filter, which verifies that the outlier‐resistant FD filter weakens the influence of measurement outliers effectively. Finally, two examples are provided to demonstrate the feasibility and effectiveness of the designed FD scheme. [ABSTRACT FROM AUTHOR]

The densification of a SiCp/Al–Fe–V–Si billet was achieved by reducing the pores and oxide film between the particles by rolling. The wedge pressing method was used to improve the formability of the composite after jet deposition. The key parameters, mechanisms, and laws of wedge compaction were studied. The results showed that the pass rate was reduced by 10 to 15 percent when using steel molds during the wedge pressing process if the distance between the two ends of the billet was about 10 mm, which was beneficial to improve the compactness and formability of the billet. The density and stress of the surface of the material were higher than those of the interior, where the distribution of density and stress tended to be uniform as the overall volume of the material shrank. During the wedge extrusion process, the material in the preforming area was thinned along the thickness direction, while the material in the main deformation area was lengthened along the length direction. Under plane strain conditions, the wedge formation of spray-deposited composites follows the plastic deformation mechanism of porous metals. The true relative density of the sheet was higher than the calculated value during the initial stamping phase, but was lower than the calculated value when the true strain exceeded 0.55. This was due to the accumulation and fragmentation of SiC particles, which made the pores difficult to remove. [ABSTRACT FROM AUTHOR]

Wrinkles, as a form of mechanical instability, can be employed in many different areas, including self-cleaning coating, flexible electronics, smart adhesion, channel for microfluidic devices, and mechanical property measurements. After two decades of research, the wavelength and amplitude of wrinkles can be well controlled by proper design of physical properties of thin films and substrates. However, it is still very difficult to change their orientations and complexity in a single piece of thin film, which is critically important for many practical applications. In previous studies, the orientation of all the wrinkles are either along the same direction or can only be controlled to some extent by the patterning of relief structures which rely on the complicated lithography techniques and cannot be adjusted for a given substrate. Here, we employed the shape memory polymer (SMP) as a smart substrate, combined with local/selective heating to control the boundary conditions for the strain field, and realized the gradual change in the orientation of wrinkles in a single piece of thin film. The wrinkles with a gradual change in orientations exhibited angle-dependent colors. Furthermore, by changing the sequence of thin film coating and partial triggering of an SMP, complex surface features with a sharp interface can be obtained. Finite element simulation investigations uncover the basic principles and requirements that need to be satisfied, as well as the limitations of our method, to generate wrinkles with controlled orientations in a single piece of thin film. [ABSTRACT FROM AUTHOR]