Crystal structure and catalytic performance for direst oxidation of propylene to acrylic acid of MoVTeNbO_(x) prepared by high-pressure hydrothermal synthesis

MoVTeNbO_(x) catalysts were prepared through a high-pressure hydrothermal method,in which the crystalline structure and properties of the catalysts were tuned by varying the system pressure(0-12.0 MPa).Results showed that the system pressure had a significant influence on the structure and catalytic performance of MoVTeNbO_(x).Under 3.0 MPa,MoVTeNbO_(x) prepared possessed the highest content of M1 phase(90.6%)and V5+content(60.7%),exhibiting a uniform short and thick needle-like morphology.Also,it showed excellent selectivity(79.1%)and yield(52.8%)to acrylic acid at the catalytic temperature of 380℃.However,under 4.4 and 11.6 MPa,the characteristic peaks of M1 shifted to a certain extent and the morphology changed from short and thick to slender.As a result,the V5+content of M1(001)plane decreased,resulting in a remarkable decline of the selectivity to acrylic acid.Moreover,DFT simulation results showed that the anti-bond orbital energy of V-O bond is the highest under 3.0 MPa,while further increase of pressure leads to obvious extrusion between atoms in the internal structure of MoVTeNbO_(x).Moreover,it was clear that the lower the anti-bond orbital energy of V-O bond,the lower the selectivity to acrylic acid.

Modeling and Analysis of Risk Propagation and Loss Causing Capacity for Key Nodes in Cyber-Physical Coupled Power Network

The modern power system has evolved into a cyber-physical system with deep coupling of physical and information domains,which brings new security risks.Aiming at the problem that the“information-physical”cross-domain attacks with key nodes as springboards seriously threaten the safe and stable operation of power grids,a risk propagation model considering key nodes of power communication coupling networks is proposed to study the risk propagation characteristics of malicious attacks on key nodes and the impact on the system.First,combined with the complex network theory,a topological model of the power communication coupling network is established,and the key nodes of the coupling network are screened out by Technique for Order Preference by Similarity to Ideal Solution(TOPSIS)method under the comprehensive evaluation index based on topological characteristics and physical characteristics.Second,a risk propagation model is established for malicious attacks on key nodes to study its propagation characteristics and analyze the state changes of each node in the coupled network.Then,two loss-causing factors:the minimum load loss ratio and transmission delay factor are constructed to quantify the impact of risk propagation on the coupled network.Finally,simulation analysis based on the IEEE 39-node system shows that the probability of node being breached(α)and the security tolerance of the system(β)are the key factors affecting the risk propagation characteristics of the coupled network,as well as the criticality of the node is positively correlated with the damage-causing factor.The proposed methodological model can provide an effective exploration of the diffusion of security risks in control systems on a macro level.

Modeling and Control of a V2G Charging Station Based on Synchronverter Technology

This paper proposes an idea for modeling and con-trol of a V2G charging station(CS)for electric vehicles(EVs)by using synchronverter technology.First,the architecture of the CS is introduced.Then,a T-S fuzzy controller is designed to decide the reference real power of the synchronverter by considering the grid frequency.Due to the inner frequency-and voltage-drooping mechanisms of the synchronverter,the input and output real and reactive power of the CS will be automatically adjusted on the basis of the reference value according to the degree of deviation from the nominal value of the grid frequency and voltage.To ensure the safety of this operation,an adaptive frequency droop coefficient mechanism is designed to adapt the change of the total energy storage of a CS unit by changing the slope of the P-f control characteristic of the synchronverter.The performance of the CS with the proposed control strategy is investigated with EVs of different battery states,different users’sets and under different grid status.Simulation results demonstrate that the proposed strategy can not only effectively perform controlled charging/discharging of each single electric vehicle inside the CS,but also improve the performance of the electricity grid in terms of efficiency,stability and reliability.

An Intrusion Detection Method for Advanced Metering Infrastructure System Based on Federated Learning

An advanced metering infrastructure(AMI)system plays a key role in the smart grid(SG),but it is vulnerable to cyberattacks.Current detection methods for AMI cyberattacks mainly focus on the data center or a distributed independent node.On one hand,it is difficult to train an excellent detection intrusion model on a self-learning independent node.On the other hand,large amounts of data are shared over the network and uploaded to a central node for training.These processes may compromise data privacy,cause communication delay,and incur high communication costs.With these limitations,we propose an intrusion detection method for AMI system based on federated learning(FL).The intrusion detection system is deployed in the data concentrators for training,and only its model parameters are communicated to the data center.Furthermore,the data center distributes the learning to each data concentrator through aggregation and weight assignments for collaborative learning.An optimized deep neural network(DNN)is exploited for this proposed method,and extensive experiments based on the NSL-KDD dataset are carried out.From the results,this proposed method improves detection performance and reduces computation costs,communication delays,and communication overheads while guaranteeing data privacy.

Multi-responsive red solid emitter: Detection of trace water and sense of relative humidity

A multi-responsive D-A type compound(CYQ)based on pyrone and triphenylamine was designed and successfully synthesized. The target compound exhibited distinct aggregation-enhanced emission(AEE) effect.Solvatochromic experiment and density functional theory(DFT) indicated CYQ possessed excellent intramolecular charge transfer(ICT) ability. Besides, its mechanofluorochromic property(MFC) was found with a 37 nm redshift. Powder wide-angle X-ray diffraction(PXRD) and differential scanning calorimetry(DSC) measurements were performed to demonstrate the transformation from the crystalline to amorphous states upon grinding. Surprisingly,CYQ displayed a hypersensitive response to trace water in organic solvents with an excellent detection limit as low as 0.0096% in tetrahydrofuran(THF). Furthermore, it was found that the fluorescent intensity of CYQ declined progressively upon humidity rise, and its color change can be witnessed by naked eyes. Therefore, the relative humidity(RH) sensing strategy guarantees the AIEgen to become a colorimetric sensor under various conditions.