Volume 45,Issue 11,2022 Table of Contents

1 Fire resistance analysis of cold-formed steel sandwich thin-plate shear wall under vertical loadings

XING Yonghui , WANG Weiyong , SHI Yu , ZHOU Xuhong , XU Lei

2022, 45(11):1-12. DOI: 10.11835/j.issn.1000-582X.2021.054

[Abstract](404) [HTML](477) [PDF 5.75 M](641)

Abstract:
In order to obtain the fire-resistance performance of cold-formed steel sandwich thin-plate shear wall, seven models of cold-formed steel sandwich thin-plate shear wall were established by using finite element software ABAQUS, and the temperature distribution of cold-formed steel sandwich thin-plate shear wall under fire, as well as the influence of axial pressure ratio, thickness of side columns of cold-formed steel sandwich thin-plate shear wall and vertical stiffeners on the fire-resistance performance of the walls were analyzed. The results show that the temperature of the embedded steel plate is 80% of the maximum temperature of the wall after it has been exposed to fire for 2 hours, and the temperature at the web of the hat shaped section on the back fire surface of the side column and vertical stiffener is about one fourth of that of the corresponding position of the fire surface. With the increase of axial compression ratio, the damage position of the wall under fire moves up and changes from global buckling to local buckling. The thickness of the side column has a great influence on the failure mode and fire resistance limit of the wall, and it is recommended that the thickness of the side column should be not less than 2.5 mm. The wall with stiffener can use vertical stiffeners to balance the uneven tension of steel plate caused by premature buckling of stiffener, which can delay the damage of the wall under fire. The bending direction of the wall is related to the bearing capacity of side column, and when the wall is bent, the hat brim of the side column first bends greatly, and then the whole section yields.

2 Mechanical behavior of the bottom flange bolted and top flange welded joints between concrete-filled steel tubular columns and steel beam

RONG Xian , SHI Xiaona , CHEN Lei , DU Yansheng , ZHANG Jianxin

2022, 45(11):13-24. DOI: 10.11835/j.issn.1000-582X.2021.070

[Abstract](299) [HTML](486) [PDF 5.01 M](597)

Abstract:
In order to study the mechanical behavior of the bottom flange bolted and top flange welded joints with vertical stiffener between concrete-filled steel tubular columns and H-shaped steel beams, three joint members were designed and manufactured, and their pseudo-static tests were carried out with the connection mode of upper flange and the cross-section size of the beam as test parameters. At the same time, DSCM (digital speckle correlation method) measurement system was introduced to measure the strain in the core area of the node with non-contact high precision. The results show that the main damage locations of the components are near the weld due to the quality of the weld seam. The damage of the bottom flange bolted and top flange welded joints occurs at the weld joints of the upper flange and the outer ring plate of the beam, while the damage of the full bolt joints occurs at the weld joint between the inner diaphragm and the column. The core area deformation of the bottom flange bolted and top flange welded joints is smaller than that of the full bolt joint, suggesting that it is more in line with the criterion of "strong column and weak beam". It can be concluded that the load transfer between beam and column is mainly through the outer ring plate, but the ductility of full-bolted joints is significantly better than that of the bottom flange bolted and top flange welded joints due to the slippage of bolts and fewer welding defects. Moreover, beam cross-section size and joint connection mode have a greater impact on the stress performance and strain distribution in the core area, and the principal strain and shear strain nephogram in the core area develop obliquely at 45 degrees.

3 The prestressing loss of concrete beams after exposed to fire

HAO Chaowei , ZHANG Yueshan , WANG Mingfa , CHEN Yanjiang

2022, 45(11):25-33,45. DOI: 10.11835/j.issn.1000-582X.2021.053

[Abstract](310) [HTML](629) [PDF 4.83 M](598)

Abstract:
The high temperature produced in fire has a great influence on the pretensioned pre-stressed concrete beams. Due to the decrease of the effective prestressing force in the structure, the compressive stress spread over edge girth in tension is reduced, and structural cracks appear early, resulting in the decrease of service performance and durability. To detect the effective prestressing force of the pre-stressed concrete beams exposed to fire quickly, thirty-two pieces of beams exposed to fire were taken as samples. The regression formula of spalling depth ratio and prestress loss ratio was obtained by measuring the permanent stress of steel strand of concrete girder bridge after exposed to fire, and the applicability of the formula was verified by an experimental and finite element analysis on ultimate bearing capacity. The results show that the phenomenon of prestress loss of beam prestressed steel bundle exists. When the spalling depth of concrete exceeds 1/3 of the net protective layer of steel strand, the prestress loss cannot be ignored. The thickness of the steel strand protective layer should be increased appropriately for pretensioned prestressed concrete structures in fire resistance design. When the spalling depth of concrete exceeds 2/3 of the net protective layer of steel strand, the rate of prestressing loss due to high-temperature creep exceeds 10%, resulting in severe decrease of the girder stiffness.

4 Research on seismic behavior of prefabricated shear wall with innovative horizontal joint

CHEN Ting , LI Jianbao

2022, 45(11):34-45. DOI: 10.11835/j.issn.1000-582X.2020.067

[Abstract](329) [HTML](522) [PDF 4.56 M](632)

Abstract:
Based on an existing assembly shear wall with bolt-steel-bolt horizontal connector (PSW-1), an innovative prefabricated shear wall with bolt-steel horizontal connector (PSW-2) is designed. The theoretical analysis models of three specimens, including PSW-1, PSW-2 and a cast-in-place shear wall(SW-1), are established by finite analysis software ABAQUS. PSW-1 is analyzed under monotonic load, and the feasibility and accuracy of simulation method used in this paper is confirmed based on the comparison of load-displacement curves between the simulation and the test result. The seismic behavior of three specimens under cyclic load is studied and compared based on the finite element simulation result. The result of the research shows that the seismic behavior of PSW-2 is generally better than that of PSW-1. The bearing capacity and stiffness of PSW-2 and SW-1 are basically in good agreement. The deformability of PSW-2 is slightly better than that of SW-1, while the energy-dissipating capacity of PSW-2 is lower than that of SW-1. The failure mode of PSW-1, PSW-2 and SW-1 are different.

5 Study on road performance of rubber and plastic alloy modified asphalt mixture

LI Ningli , WANG Meng , ZHAO Xinpo

2022, 45(11):46-58. DOI: 10.11835/j.issn.1000-582X.2022.11.005

[Abstract](306) [HTML](457) [PDF 2.12 M](812)

Abstract:
In order to explore the road performance of rubber-and-plastic-alloy-modified asphalt mixture, the rubber-and-plastic is prepared from waste tire rubber and powder and waste plastic by precision mixer, and used to modify the matrix asphalt and mixture.The molding parameters of AC-13 and SMA-13 rubber-and-plastic-alloy-modified asphalt mixture are determined by orthogonal test. The road performances of rubber-and-plastic-alloy-modified asphalt mixture and waste-tire-rubber-and-powder-modified asphalt mixture are compared by rutting test, immersion marshall test, freeze-thaw splitting test and beam bending test. The results show that the molding parameters of AC-13 rubber-and-plastic-alloy-modified asphalt mixture are asphalt to aggregate ratio 4.8%, mixing temperature 180 ℃ and compaction temperature 165 ℃, and the molding parameters of SMA-13 rubber-and-plastic-alloy-modified asphalt mixture are asphalt to aggregate ratio 6.1%, mixing temperature 185 ℃ and compaction temperature 170 ℃. Compared with waste-tire-rubber-and-powder-modified asphalt mixture, rubber-and-plastic-alloy-modificd asphalt mixture has better high-temperature stability and water stability, but poor low-temperature crack resistance.

6 Fault location of active distribution network based on traveling wave feature classification

XU Xianfeng , XU Chenjie , ZHANG Yanbo , ZHAO Yi , WANG Shixin

2022, 45(11):59-68. DOI: 10.11835/j.issn.1000-582X.2021.219

[Abstract](310) [HTML](364) [PDF 1.60 M](1027)

Abstract:
With the access of distributed generator (DG), the power flow direction and structure of distribution networks have changed. Therefore, many traditional fault location methods are no longer applicable. Single-phase-to-ground fault is a common fault in distribution networks, which may bring secondary fault and even blackout. Based on the relationship between the wavelet eigenvalues of traveling waves and the fault section of distribution lines with DG, the optimal fault features were selected by dimension reduction of linear discriminant analysis (LDA), and then the Bayesian construction classification model based on kernel distribution was used to realize a new method of single-phase-to-ground fault location. The IEEE 33 bus model with DG was constructed to test the faults in different sections of active distribution networks. The location accuracy of the optimal three-dimensional feature sample reached 97.9%, demonstrating that the proposed method can achieve accurate fault location.

7 Flux observer design and coordinated control method for hybrid permanent magnet vernier machine

BAO Guangqing , QI Wugang

2022, 45(11):69-79. DOI: 10.11835/j.issn.1000-582X.2021.207

[Abstract](304) [HTML](704) [PDF 4.93 M](890)

Abstract:
In order to solve the problems of large volume and high energy consumption of traditional permanent magnet top drive drilling system, hybrid permanent magnet vernier machine (HPMVM) is introduced into the top drive drilling system to form a new direct drive top drive system. In this paper, the coordinated control of flux observation and drive is studied. Firstly, the decoupling of permanent magnet flux linkage is realized in two-phase rotating coordinates, and a super twisting algorithm (STA) sliding mode permanent magnet flux observer is designed to realize the accurate observation of permanent magnet flux linkage. Then, the mapping relationship between the different speed ranges and the charging/demagnetizing state of the low coercivity permanent magnet is established, and the optimal torque control strategy combined with partition control is proposed. In the low-speed region, the optimal torque can be obtained when the motor is in saturation magnetization state; in the high-speed region, in order to reduce the excitation loss caused by the motor’s continuous adjustment of the permanent magnet magnetization state, the segmented magnetization control is adopted. Under the limitation of stator voltage and current, the Lagrange auxiliary function is constructed, and the optimal torque is obtained by calculating the extreme value of the function. Finally, compared with the traditional flux weakening control, the simulation shows that the STA sliding mode flux observer can quickly and accurately identify the permanent magnet flux, which can achieve the maximum torque output in the full speed domain, and reduce the copper consumption of the motor, thus improving the efficiency of the whole motor system.

8 Control of grid-connected inverter without voltage sensor based on virtual impedance

AI Yongle , PAN Zhihang , DU Mingzhu , LI Gangxing

2022, 45(11):80-90. DOI: 10.11835/j.issn.1000-582X.2021.208

[Abstract](300) [HTML](430) [PDF 7.00 M](800)

Abstract:
The interface impedance can filter out harmonics, but interface impedance and voltage sensors increase the size, power loss, and complexity of the system. To solve these problems, a virtual impedance-based voltage sensor-free control scheme is proposed to have the inverter grid-connected. The inverter model and the principle of virtual impedance implementation are elaborated, and a virtual impedance-based control method is proposed to achieve interface impedance-free and AC voltage-sensor-free control. In addition, a method is proposed to use current sensor synchronization at startup. To reduce the complexity of the system, only virtual resistors are used for self-synchronization. The stability and dynamic characteristics of the proposed methods were verified by comparing Matlab/simulink simulations with experimental results.

9 Urban rail transit short-term passenger flow origin-destination forecast based on LSTM and GCN

TANG Jiqiang , YANG Luqi , YANG Wu

2022, 45(11):91-99. DOI: 10.11835/j.issn.1000-582X.2022.11.009

[Abstract](582) [HTML](737) [PDF 4.29 M](872)

Abstract:
The urban rail transit passenger flow origin-destination (OD) matrix has temporal correlation, spatial correlation. According to the spatio-temporal characteristics of passenger flow OD, a short-term prediction method based on long short-term memory (LSTM) neural network and graph convolution network (GCN) is proposed. The proposed prediction method uses the LSTM neural network to capture the temporal correlation, employs the GCN to capture the spatial correlation of the passenger flow, and builds the passenger flow OD matrix based on exit stations to train and test the passenger flow of the whole road network. The experiment shows that the short-term prediction modelled by combing LSTM neural network and GCN can predict the urban rail transit passenger flow OD more effectively. Compared with the single LSTM neural network, the proposed method reduces the prediction error, and is more suitable for short-term passenger flow OD prediction.

10 Complex street scene change detection based on segnet network and migration learning

YU Xiaona , HUANG Liang , CHEN Pengdi

2022, 45(11):100-107. DOI: 10.11835/j.issn.1000-582X.2022.11.010

[Abstract](356) [HTML](626) [PDF 6.83 M](824)

Abstract:
The use of multi-temporal panoramic block images is of great significance for monitoring urban development and assisting government decision-making. However, due to the influence of solar rays, ground spectrum and shooting angle during the process of collecting data, it is difficult to obtain high precision by traditional methods. Complex neighborhood changes information. To this end, this paper proposes a method for detecting image change in panoramic blocks based on Segnet and migration learning. Firstly, the data set "TSUNAMI" is pre-trained and the training set is classified and merged. Then, the Segnet network is used to semantically segment the panoramic block image, and the semantic segmentation result is subjected to difference calculation to obtain the change result map and evaluate the accuracy. Experiments were carried out to select two groups of panoramic block images. The maximum likelihood method, the support vector machine method and the method proposed in this paper were used to compare the two groups of data. The accuracy of the first group was 65.1%, 72.1% and 81.4%, respectively. The accuracy of the second group was 66.5%, 70.6%, and 82.2%, respectively. The experimental results show that the proposed method has higher detection accuracy and can provide technical support for urban violation investigation, post-disaster reconstruction, and ancient cultural relics restoration.

11 A lottery ticket-based deep transfer sparse neural network for plant disease identification

ZHANG Xu , CHEN Zhikui , LI Qiucen , LI Peng , GAO Jing

2022, 45(11):108-116. DOI: 10.11835/j.issn.1000-582X.2022.11.011

[Abstract](304) [HTML](525) [PDF 1.01 M](551)

Abstract:
In agriculture, the plant disease identification can increase the production of crops. The existing data-driven deep plant disease identification methods are based on a great number of supervised data, posing vast challenges on detecting new pests of few data. And there are many trainable parameters in those deep learning-based methods, costing much computation resources. To solve those challenges, a lottery ticket-based deep sparse transfer method is proposed for the plant disease identification. Specifically, the deep lottery ticket hypothesis is introduced, in which a compressing strategy is designed to construct the deep sparse network that distills useful information in the auxiliary domains, improving the transfer efficiency. Then, a deep lottery ticket transfer algorithm is proposed to train a deep plant disease identification model that can effectively detect the new pests of few data. Finally, the proposed method is evaluated on the representative datasets, i.e., CIFAR-10 and PlantVillage, and the accuracy of detecting new pests can achieve 97.69% in plantViuage with 70%-parameter-reduction.

12 Analysis on the cause prediction of general aviation accidents based on fuzzy cognitive map

ZHAO Ganchao , CHEN Yonggang , LEI Jingjing

2022, 45(11):117-126. DOI: 10.11835/j.issn.1000-582X.2022.11.012

[Abstract](320) [HTML](368) [PDF 3.46 M](737)

Abstract:
With the rapid development of general aviation industry, the number of general aviation accidents increases year by year.In order to effectively predict and prevent accidents,reduce the loss of life and property, it is particularly important to predict the cause of accidents.Through the statistics and classification of the causes of general aviation accidents in the ten years from 2006 to 2015, the fuzzy cognitive map prediction model is established.According to the calculation method of fuzzy cognitive map, the state values of each factor can be obtained after the system reaches the stability.By calculating the correlation degree, the order of influencing factors of general aviation accidents is obtained, and finally the main factors leading to general aviation accidents are obtained.It is found that this method is feasible to predict the causes of general aviation accidents after verification and analysis with examples, and the main causes of general aviation accidents can be successfully predicted by this method.

13 A target tracking method based on data fusion

GU Baoguo , CHEN Yang

2022, 45(11):127-134. DOI: 10.11835/j.issn.1000-582X.2022.11.013

[Abstract](327) [HTML](834) [PDF 3.25 M](595)

Abstract:
In order to improve the phased array tracking performance, a target tracking method based on data fusion is presented for measurement information of multisource. In the method, data extrapolation and time delay correction, data detection, coordinate transform are carried out in turn. Then smooth filtering for measurement data is carried out and data fusion through dynamic weighted, which improves tracking and predicting performance, is used at last. The simulation result shows that the proposed target tracking method based on dynamic weighting data fusion has higher accuracy of tracking, which can meet requirement of system.

Home

Volume 45,Issue 11,2022 Table of Contents

Current Issue

Volume

Issue

Most Read

Most Cited

Most Downloaded