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Carbon nanotubes (CNTs) and graphene have commonly been applied as the sensitive layer of strain sensors. However, the buckling deformation of CNTs and the crack generation of graphene usually leads to an unsatisfactory strain sensing performance. In this work, we developed a universal strategy to prepare welded CNT–graphene hybrids with tunable compositions and a tunable bonding strength between components by the in situ reduction of CNT–graphene oxide (GO) hybrid by thermal annealing. The stiffness of the hybrid film could be tailored by both initial CNT/GO dosage and annealing temperature, through which its electromechanical behaviors could also be defined. The strain sensor based on the CNT–graphene hybrid could be applied to collect epidermal bio-signals by both capturing the faint skin deformation from wrist pulse and recording the large deformations from joint bending, which has great potential in health monitoring, motion sensing and human–machine interfacing.

Distributed wind and photovoltaic (PV) power generation are boosting in China. The wide integration of these generators into the distribution network leads to the risk of branch overload and bus voltage violation. To cope with the above risk, some peak output of wind turbines and PV equipment may be curtailed. Although curtailment measure leads to the increase of wind and PV power generation cost, more wind and PV electricity can be integrated into distribution network. In order to balance the power supply cost and the penetration rate of wind and PV electricity, the principle of economic consumption is introduced. Then an optimization planning method considering wind and PV electricity curtailment measure is proposed, and a fast model solving method based on distribution network steady-state security region is proposed. The main work is as follows. Firstly, a maximum and minimum optimization planning model is established. The maximum optimization refers to the maximum consumption of renewable energy electricity during the operation scheme formulating. The minimum optimization refers to choosing the planning scheme with the lowest power supply cost. Secondly, steady-state security region of distribution network is used to solve the optimization model quickly. To the maximum optimization, the model is transformed into a linear programming model with the help of the security region linear expression in power injection space. To the minimum optimization, an initial solution formulation method based on the redundancy information of the system operation state is given, by which the initial solution is close to the final solution. Finally, a case study of the IEEE 33-bus system is carried out and proves the effectiveness of the method. It is found that under the principle of economic consumption, the penetration rate of renewable energy electricity can be effectively improved when suitable renewable electricity curtailment measure is taken.

Distributed generators are being widely integrated into China’s urban distribution network unevenly, which accounts for different load rates of distribution transformer cluster in spatial dimension and low net load simultaneity rate in temporal dimension. Therefore, it is necessary to carry out flexible dispatching for the distribution transformer cluster in active distribution network to effectively reduce the grid loss. Different from the existing research on dynamic reconfiguration of the network supplied by a single transformer or a single feeder, the grid loss of distribution transformer cluster is optimized in the paper. Firstly, a 0-1 integer optimization model is established. The model is characterized by calculating the total grid loss of distribution transformer cluster based on the connectivity of power supply path and considering the spatio-temporal constraints such as total change times of switches. Secondly, uncertainty of renewable energy output is considered with k-means clustering algorithm effectively. The reduced scenarios are used for flexible dispatching simulation. Then, the discrete monkey algorithm, characterized by the cross iteration of local optimization and global search, is improved for solving 0-1 integer programming problem. The improved method can deal with the temporal coupling constraints in the model. Finally, the effectiveness of the proposed method is identified by case study. Flexible dispatching of distribution transformer cluster can greatly reduce the grid loss of active distribution network, and the optimal dispatching scheme will change along with the change of distributed generator output.

Wrinkling is a well-known phenomenon observed at various length scales for diverse materials. Despite a variety of research studies focusing on investigating wrinkling mechanisms and utilizing them to create surface patterns recently, wrinkling also brings about the loss of specific functional properties that were initially endowed to the thin films. For instance, wrinkling may result in the degradation of electrical and optical properties of the film; and the wrinkled films are easily delaminated. Therefore, it is still meaningful to find ways for the suppression of wrinkling on the thin film, although the relevant works are far less than those that utilize the surface instability to achieve certain structures. In this review, the approaches to restrain the emergence of wrinkles will be introduced. Following the introduction part, numerical analysis for wrinkle generation will be first discussed, by which the key parameters determining wrinkle initiation and morphology will be provided. Then, wrinkle suppression strategies by tailoring these parameters will be introduced in the following sections. This review aims to provide useful guidance for future research on alleviating surface fluctuations and achieving desired device functionality.

Piezoelectric catalysis (piezocatalysis) is a physical/chemical process that utilizes piezoelectric potential for accelerating chemical reactions, in which ubiquitous mechanical energies in nature are used for various catalysis applications, e.g., treating organic water pollutants. Despite the high efficiency achieved by piezocatalytic powders, the particles used tend to diffuse in water systems and are hard to be separated, thus causing secondary pollution. Herein, a free‐standing piezocatalytic foam is designed and fabricated, which is composed of BaTiO3 nanoparticles embedded in the PVDF scaffold. The as‐prepared PVDF–BaTiO3 composite foam demonstrates outstanding piezocatalytic efficiency in removing aqueous organics among state‐of‐the‐art integral piezocatalytic platforms, which lie in the synergy of piezoelectric materials and abundant interconnected pores within the foam. Significantly, PVDF–BaTiO3 foam is further applied for purifying natural water samples, by which the permanganate index of the water sample reduces by nearly 30% after 2 h of treatment. In addition, as a monolithic platform, PVDF–BaTiO3 foam is easy to be collected, with high reuse stability and applicability for treating various pollutants, resulting in dominant advantages over powder‐based systems for practical high‐flux wastewater treatment. Herein, a piezocatalytic platform is provided for the effective degradation of organic pollutants in water, with minimal environmental side effects.