Configuration of an Energy Storage System Considering the Frequency Response and the Dynamic Frequency Dispersion

The high proportion of renewable energy sources (RESs) in the system reduces the frequency support capacity and aggravates the generation of unbalanced power, while the dynamic frequency dispersion makes it difficult for a centralized energy storage system (ESS) to take into account the frequency requirements of different regions. In this context, the research takes the region with high penetration of RESs and frequent power fluctuations as the grid node of the ESS. By configuring the parameters of the ESS under the control strategy of virtual synchronous generators, the inertia and the primary frequency reserve of the system are supplemented, and the regulation characteristics of the ESS are depicted. Taking the steady-state recovery time and the amplitude coefficient as the evaluation indexes, the effects of the virtual inertia constant, the virtual damping coefficient, and the virtual frequency regulation coefficient on the behavior of the ESS are deeply analyzed. Finally, the quantitative configuration of the ESS is realized by considering the frequency response and the dynamic frequency dispersion.

A Grade Identification Method of Critical Node in Urban Road Network Based on Multi-Attribute Evaluation Correction

Accurately identifying the key nodes of the road network and focusing on its management and control is an important means to improve the robustness and invulnerability of the road network. In this paper, a classification and identification method of key nodes in urban road networks based on multi-attribute evaluation and modification was proposed. Firstly, the emergency function guarantee grade of road network nodes was divided by comprehensively considering the importance of road network nodes, the consequences of failure, and the degree of difficulty of recovery. The evaluation indexes were selected according to the local attributes, global attributes, and functional attributes of the road network topology. The spatial distribution patterns of the evaluation indexes of the nodes were analyzed. The dynamic classification method was used to cluster the attributes of the road network nodes, and the TOPSIS method was used to comprehensively evaluate the importance ranking of the road network nodes. Attribute clustering of road network nodes by dynamic classification method (DT) and the TOPSIS method was used to comprehensively evaluate the ranking of the importance of road network nodes. Then, combined with the modification of the comprehensive evaluation and ranking of the importance of the road network nodes, the emergency function support classification results of the road network nodes were obtained. Finally, the method was applied to the road network within the second Ring Road of Beijing. It was compared with the clustering method of self-organizing competitive neural networks. The results show that this method can identify the key nodes of the road network more accurately. The first-grade key nodes are all located at the more important intersections on expressways and trunk roads. The spatial distribution pattern shows a “center-edge” pattern, and the important traffic corridors of the road network show a “five vertical and five horizontal” pattern.

Numerical Studies of Atomic Three-Step Photoionization Processes with Non-Monochromatic Laser Fields

The atomic selective multi-step photoionization process is a critical step in laser isotope separation. In this article, we have studied three-step photoionization processes with non-monochromatic laser fields theoretically based on the semi-classical theory. Firstly, three bandwidth models, including the chaotic field model, de-correlation model and phase diffusion model, are introduced into the density matrix equations. The numerical results are made comparisons comprehensively. The phase diffusion model is selected for further simulations in terms of the correspondence degree to physical practice. Subsequently, numerical calculations are carried out to identify the influences of systematic parameters, including laser parameters (Rabi frequencies, bandwidths, relative time delays, frequency detunings) and atomic Doppler broadening, on photoionization processes. In order to determine the optimum match between different systematic parameters, ionization yield of resonant isotope and selectivity factor are adopted as evaluation indexes to guide the design and optimization process. The results in this work can provide a rewarding reference for laser isotope separation.

River Segmentation of Remote Sensing Images Based on Composite Attention Network

River segmentation of remote sensing images is of important research significance and application value for environmental monitoring, disaster warning, and agricultural planning in an area. In this study, we propose a river segmentation model in remote sensing images based on composite attention network to solve the problems of abundant river details in images and the interference of non-river information including bridges, shadows, and roads. To improve the segmentation efficiency, a composite attention mechanism is firstly introduced in the central region of the network to obtain the global feature dependence of river information. Next, in this study, we dynamically combine binary cross-entropy loss that is designed for pixel-wise segmentation and the Dice coefficient loss that measures the similarity of two segmentation objects into a weighted one to optimize the training process of the proposed segmentation network. The experimental results show that compared with other semantic segmentation networks, the evaluation indexes of the proposed method are higher than those of others, and the river segmentation effect of CoANet model is significantly improved. This method can segment rivers in remote sensing images more accurately and coherently, which can meet the needs of subsequent research.

The Study on the Substrate Effect in the Nanoindentation Experiment of the Hybrid Material

The nanoindentation (NI) experiment is an effective method to evaluate the micromechanical property of materials. The substrate effect is a nonnegligible factor which could influence the accuracy of the NI experiment result. Large numbers of previous studies have focused on the substrate effect based on the coating/substrate model, whereas the substrate effect in the testing of the hybrid material was rarely involved. The real NI experiment and the numerical simulation method were adopted to reveal the characteristics of the substrate effect in the NI experiment of the hybrid material in this paper, such as the rock or cement material. The peak displacement h peak and the residual displacement h residual of the indenter, which could obtain directly from the NI experiment and were usually considered as key basic variables to calculated other parameters, were selected as evaluation indexes of the substrate effect. The results indicated that there was a significant difference of the NI experiment result between the coating/substrate and the hybrid material under the same condition. The lateral boundary stiffness and discontinuous face were considered as main factors that induced this difference, and their effect were analysed, respectively. Young’s modulus E s and Poisson’s ratio μ s of the substrate were selected as the variables in the parametric study, and the relationship between them and the NI experiment result were discussed.

E-Commerce Picture Text Recognition Information System Based on Deep Learning

For the accuracy requirements of commodity image detection and classification, the FPN network is improved by DPFM ablation and RFM, so as to improve the detection accuracy of commodities by the network. At the same time, in view of the narrowing of channels in the application of traditional MWI-DenseNet network, a new GTNet network is proposed to improve the classification accuracy of commodities.The results show that at different levels of evaluation indexes, the dpFPN-Netv2 algorithm improved by DPFM + RFM fusion has higher target detection accuracy than RetinaNet-50 algorithm and other algorithms. And the detection time is 52 ms, which is significantly lower than 90 ms required for RetinaNet-50 detection. In terms of target recognition, compared with the traditional MWI-DenseNet neural network, the computation amount of the improved MWI DenseNet neural network is significantly reduced under different shunt ratios, and the recognition accuracy is significantly improved. The innovation of this study lies in improving the algorithm from the perspective of target detection and recognition, so as to change the previous improvement that only can be made in a single way.

Evaluation of Concrete Durability Based on Cloud Model and D-S Evidence Theory

The environment in alpine region is complex and harsh, and the durability of concrete is seriously affected by freeze-thaw and salt invasion. In this paper, the relative dynamic modulus of elasticity, chloride permeability coefficient, mass loss rate and carbonation depth are selected as the evaluation indexes of concrete durability in Northeast China. Based on prior knowledge and expert group decision-making, the durability grade is divided and the evaluation standard is established; The evaluation model of concrete durability based on cloud model and D-S evidence theory is established. According to the engineering experimental data, the membership degree of concrete durability evaluation index in different grades is obtained through the correlation measurement of cloud model. The normalized evidence is formed and fused by D-S evidence theory. The results show that the durability grade of concrete is grade I, which is consistent with the actual project. It shows that using cloud model and evidence theory evaluation model to evaluate the durability of concrete is a new and effective method.

Optimisation of Driver’s Traffic Literacy Evaluation Index from the Perspective of Information Contribution Sensitivity

The practice has proven that relying solely on large-scale transportation facilities cannot fundamentally alleviate urban transportation problems. Since the motor vehicle drivers are the main participants of transportation, they should improve their knowledge of transportation. Moreover, the drivers should equally cope with transportation problems. This paper establishes an evaluation index system for traffic literacy of urban drivers. In addition, it proposes a method of information contribution sensitivity to optimise the index system. The main results and achievement of this paper include the following: (1) A traffic literacy evaluation index system including 13 evaluation indexes such as traffic rules and general knowledge of machinery has been constructed. (2) Based on the calculation results of the sensitivity of the information contribution, the first 10 indexes that satisfy the cumulative information contribution rate’s value of greater than 90% are retained and 3 indexes with lower contribution rates are eliminated. This study provides a theoretical framework and basic methods to evaluate the traffic literacy of urban drivers.

RESEARCH STATUS AND DEVELOPMENT TREND OF MECHANIZED STRAW RETURNING TECHNOLOGY. A REVIEW

As the application of agricultural mechanized production technology becomes more and more extensive, the application of mechanized straw returning technology has become more and more valuable. The mechanized return of straw to the field is a time-saving and labor-saving technology. It is an effective way to achieve sustainable agricultural development and is of great significance to the development and progress of modern agriculture. This article analyzes the current research status of mechanized straw returning to the field, discusses the process structure and characteristics of different mechanized straw returning methods, and focuses on the analysis of the composite technology of straw returning to the field. At the same time, the key problems of straw returning to the field, such as the length of straw not meeting the standard, the shallow depth of straw returning to the field, and the uneven distribution of straw, are put forward and analyzed. By taking the cover and burial rate of straw on the soil surface and the spatial distribution uniformity of straw in the soil as the performance evaluation indexes of straw mechanized field return, each index is elaborated. Finally, two major development trends are proposed: the development of mechanized straw returning to the field from a single process to a composite process, and the effect of straw returning to the field towards uniform mixed burying and precise control.

EFFECT OF SEED FILLING AND RELEASING ANGLES ON THE PERFORMANCE OF COMPOUND VACUUM SEED METERING DEVICE

In this paper, taking compound air-suction seed metering device as the subject, the effect rule of seed filling angle and seed releasing angle on the performance of seed filling and seed metering is studied. An indoor test was conducted with a JPS-12 metering test bench and a high-speed camera system. The starting and ending angles of the air chamber were changed by adjusting the regulating plate, that is, the angles of seed filling and seed releasing, and the filling and seed metering performance was taken as evaluation indexes. The test results show that: the seed filling angle has significant effect on the seed filling effect, and the miss fill index decreases with the increase of the quality of fill index. When the seed filling angle exceeds 50°, they will stabilize gradually ending at the multiple fill index of 0%. The negative pressure and operating speed are interactive and have a significant effect on filling performance. The seed releasing angle has significant effect on the metering performance. With the increase of the angle, the quality of feed index increases firstly and then decreases. The multiple index and miss index are opposite to the quality of feed index which is the max at the seed releasing angle of 39.5°. The negative pressure and forward speed are interactive and have a significant effect on metering performance. The quality of feed index under the same condition is lower than that of fill index.