Search

This work presents the unique advantage of textiles in constructing piezocatalytic platforms. The mesoporous and intertwined textile could amplify the striking force of water flow, by which piezocatalysis under low-frequency water flow is achieved.

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.

International audience; Key message Bi-axis training increased vegetative shoot light interception and modeled photosynthetic rate, and reduced fruiting shoot mutual shading and vegetative growth by optimizing canopy structure compared to single-axis in young apple trees. Improving light interception and distribution within canopy are constant objectives of training through manipulating tree architecture. A bi-axis training system with two primary scaffolds has been proposed to improve flowering and dry matter production in apple trees. In this study, 'Fuji' apple trees trained using a bi-axis or single-axis training system were compared. Twelve three-dimensional (3D) virtual apple trees were reconstructed by combining 3D digitizing and allometric relationships for three shoot types (vegetative long shoot, VL; fruiting shoot, FS; vegetative short shoot, VS), to evaluate canopy structure impacts on light interception. Light interception efficiency was evaluated by silhouette to total area ratio (STAR). The potential canopy photosynthetic rate was evaluated by the eco-physiological RATP model. The leaf area of VL in bi-axis trained trees was approximately 40% lower than that in single-axis trees. Lower leaf area and more uniform spatial distribution were noted in VL in bi-axis than in single-axis trees. This led to more even spatial light distribution and more shoots having higher STAR in bi-axis than in single-axis trees, regardless of the whole tree or shoot type. In the virtual orchard, bi-axis trees had a 25% and 10% STAR increase in VS and VL, respectively, but a similar STAR for FS compared to single-axis trees. Mutual shading between neighboring trees in the virtual orchard made of bi-axis trees was significantly lower than that with single-axis trees for FS. The modeled canopy net photosynthetic rate was 26% higher in bi-axis than in single-axis trees. With the increase in tree age, the projected leaf area increased, but the porosity of the canopy decreased, and mutual shading increased for the whole canopy and all shoot types, irrespective of training systems. These results indicated that manipulating scaffolds in apple trees can regulate canopy structure, light interception, and vegetative growth during the early developmental stages.

Interfacial solar evaporators (ISEs) for seawater desalination have garnered enormous attention in recent decades due to global water scarcity. Despite the progress in the energy conversion efficiency and production rate of ISE, the poor portability of large-area ISE during transportation as well as the clogging of water transport pathways by precipitated salts during operation remain grand challenges for its fielded applications. Here, we designed an ISE with high energy conversion efficiency and shape morphing capability by integrating carbon nanotube (CNT) fillers with a light-responsive shape memory polymer (SMP, cross-linked polycyclooctene (cPCO)). Utilizing the shape memory effect, our ISE can be folded to an origami with 1/9 of its original size to save space for transportation and allow for on-demand unfolding upon sunlight irradiation when deployed in service. In addition, the ISE is equipped with a real-time clogging monitoring function by measuring the capacitance of the electric double layer (EDL) formed at the evaporator/seawater nanointerface. Due to its good energy conversion efficiency, high portability, and clogging monitoring capability, we envisage our ISE as a promising selection in solar evaporation technologies.

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.

To power system with high permeability of wind and photovoltaic (PV) power generation, the capacity configuration ratio has an important influence on power consumption and power supply cost. A capacity configuration optimal planning model is proposed in this paper, which is based on the premise of same abandonment ratio of wind and PV electricity. Then, the generation configuration schemes under multiple preset capacity ratio values were got, and the functional relationship between power supply cost and capacity configuration ratio was achieved. Extreme point of the function was searched out to find the optimal capacity ratio. Lastly, sensitivity analysis was conducted considering the change of several cost parameters. Through the analysis of case study, it is found that the proposed method here could explore the complementary potential between wind and PV power.

A generating method of long-time-scale photovoltaic (PV) output vector facing power system planning was proposed in the paper. The major feature of the method is that only several kinds of accessible data are needed, while four main functions could be realized. In the created long-time-scale PV output vector, the cyclical changes of the PV output caused by sunrise and sunset are considered, the overall trend change related to monthly or seasonal differences are considered, the changes in magnitude leaded by weather changing which usually last a few days are considered, and the adjustment of PV output to make the vector reflecting the utilization hours of local PV facility are able to realize. The effectiveness of the proposed method was verified by the simulation of PV output in Beijing region.

Advances in neural electrode technologies can have a significant impact on both fundamental and applied neuroscience. Here, we report the development of flexible and biocompatible neural electrode arrays based on a nanopaper substrate. Nanopaper has important advantages with respect to polymers such as hydrophilicity and water wettability, which result in significantly enhanced biocompatibility, as confirmed by both in vitro viability assays and in vivo histological analysis. In addition, nanopaper exhibits high flexibility and good shape stability. Hence, nanopaper-based neural electrode arrays can conform to the convoluted cortical surface of a rat brain and allow stable multisite recording of epileptiform activity in vivo. Our results show that nanopaper-based electrode arrays represent promising candidates for the flexible and biocompatible recording of the neural activity.

Flexible stimuli-responsive materials are deformable, stretchable, light-weight, and desirable for smart personal protective equipment (PPE), and as the primarily functional components in the wearable system which spontaneously respond to surrounding variations. These materials enable the traditional PPE who provide passive protection to be smart with the abilities of sensing, actuating, surface changing and self-healing, which enhances the protection and reduces the unintentional occupation injuries. This article presents a critical review of the structure, properties, fundamental mechanisms and current development of flexible stimuli-responsive materials and their potential/present applications to smart PPE, covering strain, pressure, temperature, and gas sensors, biopotential electrodes, exosystems, switchable wetting surfaces and biosafety masks. Scientific and practical challenges along with critical issues and opportunities are also discussed.

Aligned carbon nanotube (CNT) arrays are promising candidates for strain sensors owing to their scalable preparation and excellent conductivity and stretchability. However, aligned CNT arrays are limited by low strain sensitivity and buckling deformation. In addition, cross-stacked CNT array films layer-by-layer assembled on soft substrates exhibit anisotropic mechanical behavior due to their asymmetric layered structures. In this work, we introduced a chemically hybridized CNT-graphene (G/CNT) film in which CNT crossbars are effectively welded together by graphene. The hybrid films demonstrate enhanced isotropic mechanical properties and strain sensitivity with a gauge factor of ∼3, together with a high stretchability of more than 20%. The enhanced electromechanical properties are attributed to the improved load transfer efficiency among CNTs by graphene hybridization, as confirmed by Finite Element Analysis (FEA). Biaxial strain sensors based on the hybridized G/CNT films have been applied for sensitive detection of both minute vibrations caused by sound waves and large deformations from finger bending. The sensors were further integrated into a tactile sensing array to map the spatial distribution of the surface pressures.

The outbreak of the Covid-19 pandemic has aroused tremendous attention toward personal protective equipment (PPE) in both scientific research and industrial manufacture. Despite decades of development in PPE design and fabrication, there's still much room for further optimization, in terms, of both protection performance and wear comfort. Interdisciplinary efforts have been devoted to this research field in recent years. Significantly, the innovation of materials, which brings about improved performance and versatile new functions for PPEs, has been widely adopted in PPE design. In this minireview, recent progress in the development of novel materials and structural designs for PPE application are presented in detail with the introduction of various material-based strategies for different PPE types, as well as the examples, which apply auxiliary components into face masks to enrich the functionalities and improve the personal feelings in the pandemic period., Graphical abstract Image 1

Integrating electronics in clothing is a significant milestone of wearable technology. The priority is to develop flexible interconnector with great washability, durability and comfort wearability. In this work, we reported an air-permeable and machine-washable Cu/Ni interconnector based on highly flexible fibrous polyimide (FPI) membrane. Benefiting from the porous merit of FPI membrane and robust parylene encapsulation, the novel interconnector presents excellent conductivity (14 mΩ/sq), decent air-permeability (11 KPa*s/m) and superior electromechanical stability after abrasion of 50,000 cycles, bending of 10,000 cycles, and machine washing of 50 times. Moreover, assemblies made from the FPI-based circuit board not only show desirable lifespan in harsh environments, including seawater, ice, boiled water, and heavy rain, but also can be woven into fabrics for broad wearable applications. The work presents a facile and effective method to fabricate highly flexible, comfortable and durable interconnector, guaranteeing the reliability for long-term wearable application and showing great possibility for high-throughput production.

Tarkista embargo, kun artikkeli julkaistu. Flexible electronics that can form tight interfaces with neural tissues hold great promise for improving the diagnosis and treatment of neurological disorders and advancing brain/machine interfaces. Here, the facile fabrication of a novel flexible micropillar electrode array (µPEA) is described based on a biotemplate method. The flexible and compliant µPEA can readily integrate with the soft surface of a rat cerebral cortex. Moreover, the recording sites of the µPEA consist of protruding micropillars with nanoscale surface roughness that ensure tight interfacing and efficient electrical coupling with the nervous system. As a result, the flexible µPEA allows for in vivo multichannel recordings of epileptiform activity with a high signal-to-noise ratio of 252 ± 35. The ease of preparation, high flexibility, and biocompatibility make the µPEA an attractive tool for in vivo spatiotemporal mapping of neural activity.

Deterministic design of surface patterns has seen a surge of interests because of their wide applications in flexible and stretchable electronics, microfluidics, and optical devices. Recently, instability of bilayer systems has been extensively utilized by which micro-/nano-patterns of a film can be easily achieved through macroscopically deforming the underlying substrate. For a bilayer system with traditional thermostable substrates, the pattern morphology is only determined by initial strain mismatch of the two layers, and the realization of localized patterns appears to be particularly challenging because of the difficulties associated with manipulating inhomogeneous deformations. In this work, we exploit cross-linked polyethylene ( cPE), a shape memory polymer (SMP), as the flexible substrate for building micro-/nano-structures of sputtered gold films. We find that the shape memory effect can offer new dimensions for designing diverse and hierarchical surface structures by harnessing film thickness orheating time and by globally or locally controlling the thermal field. By combining those strategies, we further demonstrate versatile hierarchical, superimposed, and local surface patterns based on this cPE/gold (Au) system. Piezoresistive pressure sensors are assembled with the obtained patterned surface, which have high sensitivity, operational range, and cyclic stability. These results highlight the unique advantages of SMPs for building arbitrary surface patterns.

Transparent, stretchable films of carbon nanotubes (CNTs) have attracted significant attention for applications in flexible electronics, while the lack of structural strength in CNT networks leads to deformation and failure under high mechanical load. In this work, enhancement of the strength and load transfer capabilities of CNT networks by chemical vapor deposition of graphene in the nanotube voids is proposed. The graphene hybridization significantly strengthens the CNT networks, especially at nanotube joints, and enhances their resistance to buckling and bundling under large cyclic strain up to 20%. The hybridized films show linear and reproducible responses to tensile strains, which have been applied in strain sensors to detect human motions with fast response, high sensitivity, and durability.

This work demonstrates that engineering of the connection channels in gold thin films is an effective way to alter its resistivity for improved sensitivity in strain sensors. We investigated the formation of channel cracks and explored the corresponding piezoresistive behavior. The developed strain sensor possessed GFs as high as 200 (e < 0.5%), 1000 (0.5% < e < 0.7%), and even greater than 5000 (0.7% < e < 1%), which are among the highest values reported thus far at such small deformation, and are promising in the applications of electronic skin, wearable sensors and health monitoring platforms.

Nanomaterials serve as promising candidates for strain sensing due to unique electromechanical properties by appropriately assembling and tailoring their configurations. Through the crisscross interlacing of graphene microribbons in an over-and-under fashion, the obtained graphene woven fabric (GWF) indicates a good trade-off between sensitivity and stretchability compared with those in previous studies. In this work, the function of woven fabrics for highly sensitive strain sensing is investigated, although network configuration is always a strategy to retain resistance stability. The experimental and simulation results indicate that the ultrahigh mechanosensitivity with gauge factors of 500 under 2% strain is attributed to the macro-woven-fabric geometrical conformation of graphene, which induces a large interfacial resistance between the interlaced ribbons and the formation of microscale-controllable, locally oriented zigzag cracks near the crossover location, both of which have a synergistic effect on improving sensitivity. Meanwhile, the stretchability of the GWF could be tailored to as high as over 40% strain by adjusting graphene growth parameters and adopting oblique angle direction stretching simultaneously. We also demonstrate that sensors based on GWFs are applicable to human motion detection, sound signal acquisition, and spatially resolved monitoring of external stress distribution.

Graphene and its derivatives have gained considerable attention in recent years due to their unique two-dimensional (2D) structure, exceptional physical and chemical properties, and ease of preparation and functionalization. In this chapter, we present an overview of recent advances in the biomedical applications of graphene and its derivatives. This chapter is organized into three sections. Section 9.1, Graphene-Based Biosensors, discusses biosensors based on graphene field-effect transistors (FETs). Section 9.2, Graphene Derivative-Based Functional Carriers, describes functional carriers based on graphene derivatives for bioimaging and drug delivery. Section 9.3, Biosafety of Graphene, discusses the biosafety of graphene and its derivatives. We will conclude with the future challenges and prospects of this rapidly growing area.

Subdural surface and penetrating depth probes are widely applied to record neural activities from the cortical surface and intracortical locations of the brain, respectively. Simultaneous surface and depth neural activity recording is essential to understand the linkage between the two modalities. Here, we develop flexible dual-modality neural probes based on graphene transistors. The neural probes exhibit stable electrical performance even under 90° bending because of the excellent mechanical properties of graphene, and thus allow multi-site recording from the subdural surface of rat cortex. In addition, finite element analysis was carried out to investigate the mechanical interactions between probe and cortex tissue during intracortical implantation. Based on the simulation results, a sharp tip angle of π/6 was chosen to facilitate tissue penetration of the neural probes. Accordingly, the graphene transistor-based dual-modality neural probes have been successfully applied for simultaneous surface and depth recording of epileptiform activity of rat brain in vivo. Our results show that graphene transistor-based dual-modality neural probes can serve as a facile and versatile tool to study tempo-spatial patterns of neural activities.

Nanopore-based sequencing platforms are transforming the field of genomic science. This review (containing 116 references) highlights some recent progress on nanopore-based nucleic acid analysis and sequencing. These studies are classified into three categories, biological, solid-state, and hybrid nanopores, according to their nanoporous materials. We begin with a brief description of the translocation-based detection mechanism of nanopores. Next, specific examples are given in nanopore-based nucleic acid analysis and sequencing, with an emphasis on identifying strategies that can improve the resolution of nanopores. This review concludes with a discussion of future research directions that will advance the practical applications of nanopore technology.

The exotic emission of ballast water has threatened the coastal ecological environment and people's health in many countries. This paper firstly introduces pulse intense light to treat ballast water. 99.9 ± 0.09% inactivation of Heterosigma akashiwo and 99.9 ± 0.16% inactivation of Pyramimonas sp. are observed under treatment conditions of 350 V pulse peak voltage, 15 Hz pulse frequency, 5 ms pulse width and 1.78 L/min flow rate. The energy consumption of the self-designed pulse intense light treatment system is about 2.90-5.14 times higher than that of the typical commercial UV ballast water treatment system. The results indicate that pulse intense light is an effective technique for ballast water treatment, while it is only a competitive one when drastic decreasing in energy consumption is accomplished.

The area where UHVDC transmission lines pass by is complicated and under severe conditions, such as pollution, acidic rain, and high altitude. All of these will have very huge impacts over the insulation coordination of DC lines, therefore, the insulation coordination of UHVDC lines is a key technology in the design of ±800 kV DC transmission project. This chapter presents a discussion on insulation coordination of UHVDC transmission line, mainly includes the following two aspects: selection of type and number of DC line insulators, and air clearance determination of DC line.

Due to the high operating voltage and large working current, the 1000 kV UHVAC transmission line often generates the relatively serious electromagnetic induction problem to the adjacent AC and DC transmission lines. This chapter first calculates the induced voltage and current in the out-of-operation circuit of the 1000 kV double-circuit line on the same tower under the condition that one circuit is in operation and the other is out of operation for maintenance, then analyzes the influences of the different grounding methods for the overhead insulated ground wire and optical fiber composite overhead ground wire (OPGW) adopted for the 1000 kV AC transmission line on the induced voltage, induced current, and energy consumption in the ground wires, and finally discusses the power-frequency electromagnetic influences of the UHVAC transmission line on the UHVDC line erected in parallel with it.

Controlled synthesis of hierarchically assembled titanium dioxide (TiO2) nanostructures is important for practical applications in environmental purification and solar energy conversion. We present here the fabrication of interconnected TiO2 nanotubes as a macroscopic bulk material by using a porous carbon nanotube (CNT) sponge as a template. The basic idea is to uniformly coat an amorphous titania layer onto the CNT surface by the infiltration of a TiO2 precursor into the sponge followed by a subsequent hydrolysis process. After calcination, the CNTs are completely removed and the titania is simultaneously crystallized, which results in a porous macrostructure composed of interconnected anatase TiO2 nanotubes. The TiO2 nanotube macrostructures show comparable photocatalytic activities to commercial products (AEROXIDE TiO2 P25) for the degradation of rhodamine B (RhB). Moreover, the TiO2 nanotube macrostructures can be settled and separated from water within 12 h after photocatalysis, whereas P25 remains suspended in solution after weeks. Thus the TiO2 nanotube macrostructures offer the advantage of easy catalyst separation and recycle and can be a promising candidate for wastewater treatment.

The programmable nature of smart textiles makes them an indispensable part of an emerging new technology field. Smart textile-integrated microelectronic systems (STIMES), which combine microelectronics and technology such as artificial intelligence and augmented or virtual reality, have been intensively explored. A vast range of research activities have been reported. Many promising applications in healthcare, the internet of things (IoT), smart city management, robotics, etc., have been demonstrated around the world. A timely overview and comprehensive review of progress of this field in the last five years are provided. Several main aspects are covered: functional materials, major fabrication processes of smart textile components, functional devices, system architectures and heterogeneous integration, wearable applications in human and nonhuman-related areas, and the safety and security of STIMES. The major types of textile-integrated nonconventional functional devices are discussed in detail: sensors, actuators, displays, antennas, energy harvesters and their hybrids, batteries and supercapacitors, circuit boards, and memory devices.

Implantable electrical probes that can record neural activities at single-neuron and sub-millisecond resolution are the most widely applied tools in both neuroscience research and neuroprosthetics. However, the structural and mechanical mismatch between conventional rigid probes and neural tissues results in inflammatory responses and signal degradation over chronic recordings. Reducing the cross-sectional footprints and rigidity of the probes can effectively improve the long-term stability of neural interfaces. Herein, recent progress in the development of implantable microelectrodes for chronically stable neural interfaces is highlighted, with a focus on the utilization of advanced materials and structural design concepts.

In this study, we report the polymer-based graphene foams through combination of bottom-up assembly and simple triaxially buckled structure design. The resulting polymer-based graphene foams not only effectively transfer the functional properties of graphene, but also exhibit novel negative Poisson’s ratio (NPR) behaviors due to the presence of buckled structure. Our results show that after the introduction of buckled structure, improvement in stretchability, toughness, flexibility, energy absorbing ability, hydrophobicity, conductivity, piezoresistive sensitivity and crack resistance could be achieved simultaneously. The combination of mechanical properties, multifunctional performance and unusual deformation behavior would lead to the use of our polymer-based graphene foams for a variety of novel applications in future such as stretchable capacitors or conductors, sensors and oil/water separators and so on.

Due to the technique and economic considerations, transmission lines in the power grid are usually untransposed, which leads to the result that the line parameter is asymmetric. For double-circuit lines on the same tower, asymmetric line parameters may cause unbalanced currents even under normal operation, which will have a negative impact on the line temperature, line loss and even relay protections. This paper firstly investigates the line parameters and current characteristics of the double-circuit lines on the same tower under normal operating mode. Then, we provide a method to analyze the current characteristics including circulating current and the net through current, and effects of phasing arrangement on each kind of unbalanced components are analyzed. Finally, based on the actual parameter of tower and transmission line in power grid, unbalanced currents of a certain double-circuit line are analyzed with full consideration of different phasing arrangements. With the help of analysis results, some useful conclusions and suggestions to limit the current unbalance are listed in the last part of this paper.

Fault recovery of distribution network is realized by operating switches to change topological structure of the network. The final destination of fault recovery is power loss minimization, fault isolation and power load transfer. This article has built the mathematical model of fault recovery considering constraints of node voltage, line capacity and power flow balance. The objective function is power loss reduction. Further, the genetic algorithm is used to solve the proposed model. The optimal network structure and recovered power load could be derived through calculation. Finally, the author complied the program with Matlab and tested it on the IEEE33 bus system. The simulation and analysis results have verified the effectiveness of the proposed method. DOI : http://dx.doi.org/10.11591/telkomnika.v12i3.4567 Full Text: PDF

Smart distribution grid is the important part of smart grid which connects the main network with users. It is directly user oriented and the center of power distribution. This article has compared the smart distribution grid with regular traditional distribution network. Crucial techniques including automation technology, Informationization technology and interaction are the emphasis of discussion. The results have indicated that researches on advanced electric equipment, online monitoring, self healing, advanced metering infrastructure, integrated communication, micro gird and other technologies would be the principal directions of study on smart distribution grid, simultaneously providing reference for realization of practical application in future. KeywordsSmart distribution grid; Automation technology; Informationization technology; Interaction technology

This article has summarized the developing history of distribution automation technology and analyzed existing problems that hinder its practical application. Currently the automation level of the distribution network in our country is very low reflecting as insufficient and immature functions. The research results have shown that the development of distribution automation will be focused on diversification, integration and intellectualization. Considering the intimate connection with smart grid, the article has pointed out the further development trends of distribution automation. Keywordsdistribution automation; smart grid; development trend.