Volume 46,Issue 6,2023 Table of Contents

1 Failure mechanism of karst mountain with deep and large fissures under the influence of mining and rainfall

LIU Xinrong , RAN Qiao , XIONG Fei , LI Bin , YANG Zhongping

2023, 46(6):1-13. DOI: 10.11835/j.issn.1000.582X.2023.06.001

[Abstract](354) [HTML](83) [PDF 7.43 M](783)

Abstract:
To clarify the deformation and failure law of karst mountain with deep and large fissures under the action of mining and rainfall, by taking the Pusa landslide in Nayong County of Guizhou Province as an example, the instability and failure mechanisms of karst mountain with deep and large fissures under the action of mining and rainfall were discussed through block discrete element numerical analysis. The results show that the overlying strata of the mountain moved down to the mined-out area with the mining of coal seams M10 and M14, and new fraclures developed to the slope surface. Simultaneously, the height of the the fracture zone of the overlying strata in working face increased with the increase of the goaf range. The fracture zone developed to 30 and 40 times the mining height after mining M10 and M14, respectively, and the deep karst fissure expanded to the lower slope. After rainfall and infiltration, the fracture zone of the overlying strata was connected with deep and large karst fissures. The deep and large karst fissures expanded to the slope surface to form a potential sliding surface under the action of pore water pressure, leading to the collapse and slide of the karst slope. Through comparative study, mining is the control factor of the deformation and destruction of the Laoyingyan Mountain, and subsequent rainfall is the main inducing factor of slope instability.

2 The eigen solution and properties of a taut string with concentrated damping at one-third-span

ZHENG Gang , LIAO Wei , WANG Mengli , ZHANG Xiaodong

2023, 46(6):14-23. DOI: 10.11835/j.issn.1000.582X.2023.06.002

[Abstract](269) [HTML](67) [PDF 1.15 M](508)

Abstract:
A frequency equation of the damping string is simplified in which the damping is located at one third of the string length, and its analytical solution is obtained. The properties of the solution are discussed in three cases: large damping, moderate damping and small damping. The results show that, compared with the taut strings with damping which is located at half of the string length, the taut strings with damping which is located at one third of the string length has three new characteristics: 1) In the functional relationship between the eigenvalues and damping, the former has and only has one mutation point, while the latter has two; 2) In the damping - frequency relationship, the frequency of the former is not affected by the damping value in each damping interval, while the frequency of the latter is related to the damping; 3) For any given damping, the former eigen solution has only one attenuation rate in each damping interval, and the latter has two attenuation rates except for small damping. The above properties show that the dynamic characteristics of the two are different in essence (not only in quantity). Considering that they differ only in damping position, this should be paid special attention to.

3 Hysteretic performance of hole-opened weakened steel-plate damper in prefabricated energy-dissipating steel-hinge connection

YAN Guiyun , WANG Di , YE Jianfeng , XUE Panrong , XIAO Xiaofei

2023, 46(6):24-39. DOI: 10.11835/j.issn.1000.582X.2023.06.003

[Abstract](212) [HTML](42) [PDF 6.80 M](495)

Abstract:
In this paper, an energy-dissipating steel-hinge connection in a prefabricated joint was proposed, in which hole-opened weakened steel-plate dampers were its key parts. The axial reciprocating loading tests were conducted on three different hole-opened weakened dampers to investigate the failure mode, the hysteretic performance, skeleton curve, bearing capacity as well as the ductility. Then the effects of the weakened length and width of the hole, the width-thickness ratio, and the thickness direction gap on the hysteretic performance of the steel-plate damper were discussed. In addition, a simplified mechanical model of the weakened steel-plate damper was established to derive the hysteretic constitutive model which was verified by the experimental results. The results show that the weakened steel plate of the damper cracks or breaks at the hole-opened part, avoiding out-of-plane buckling and achieving the controllability of plastic energy dissipation and failure mode. The hysteresis curve of the dampers is full, the bearing capacity is higher than 297.31 kN, and the displacement ductility coefficient is greater than 4.5, showing good energy dissipation capacity, bearing capacity and ductility performance. Compared with diamond-shaped openings, the vertical slot-opening damper has better overall mechanical properties. It is also recommended that the weakened length a/L of the hole is from 0.25 to 0.55, the weakened width b/B is from 0.2 to 0.5, the width-to-thickness ratio is from 12.50 to 15.63, and the gap in the thickness direction cannot exceed 2 mm. The proposed hysteretic constitutive model can accurately simulate the hysteresis performance of the hole-opened weakened steel-plate damper.

4 Seismic behavior of hybrid high ductility fiber reinforced concrete composite cross-shaped short columns

WANG Xiaowei , ZHANG Wei , ZHAO Enhui , GUO Yonggang , MU Ru , ZHOU Jian , ZHAO Cancan , LIU Haoqi

2023, 46(6):40-50. DOI: 10.11835/j.issn.1000.582X.2023.06.004

[Abstract](250) [HTML](35) [PDF 2.96 M](454)

Abstract:
To improve the seismic behavior of the cross-shaped short column, the concrete was substituted with high ductility fiber reinforced concrete in the bottom of the cross-shaped short column. Quasi-static tests on the hybrid high ductility fiber reinforced concrete composite cross-shaped short column (R/ECC) and the reinforced concrete cross-shaped short column (RC) were carried out. The crack propagation mode, failure characteristics, hysteretic behavior, ductility, energy dissipation and stiffness degradation were compared to investigate the seismic behavior of the R/ECC column. The results show that the hybrid high ductility fiber reinforced concrete can effectively control the development of the crack, decrease the width of the crack and improve the state of collapse and spalling. The ductility and energy dissipation of the composite column are improved obviously. The stiffness degradation becomes lower, and the shear capacity is improved. Compared with RC column, the displacement ductility factor, as well as the cumulative hysteretic energy dissipation at the peak and limit points of R/ECC column increased by 7.3%, 225.5% and 44.6%, respectively, and the shear capacity increased by 9.5%.

5 A measurement method of occupancy based on active infrared intrusion detection

XU Wenlu , LIU Meng , LIU Huan

2023, 46(6):51-60. DOI: 10.11835/j.issn.1000-582X.2022.256

[Abstract](215) [HTML](54) [PDF 2.29 M](496)

Abstract:
Occupancy is closely related to the building energy consumption system and real-time monitoring occupancy is one of the hot issues in the study of building energy consumption behavior. Infrared sensing is a widely used method in existing research methods. Its measurement precision is related to installation height, personnel passing speed, personnel somatotype and other factors. In this study, the active infrared intrusion detector was selected to investigate the effects of installation height, passing speed and personnel somatotype on the measurement precision of occupancy according to the indoor occupants’ activities. The results show that the measurement precision first increased and then decreased with the decrease of the installation height when considering various personnel somatotype and passing speed. The slower the passing speed, the higher the measurement precision. When v≥1.4 m/s, the precision was less than 60%; when 1.0 m/s≤v<1.4 m/s, the precision was 70%~81%; when v<1.0 m/s, the precision was higher than 95%; When v<0.8 m/s, the precision was 100%. The height and body mass index(BMI) of the tested people were positively correlated with the measurement precision. Through the analysis of different operating conditions, an estimation method of comprehensive precision applied to actual scenes was proposed.

6 A cold load prediction method of shopping malls oriented to functional zoning

ZHAO Anjun , YANG Hangjie , JING Jing , ZHANG Mengzhi , JIAO Yang

2023, 46(6):61-75. DOI: 10.11835/j.issn.1000-582X.2022.252

[Abstract](232) [HTML](42) [PDF 4.08 M](661)

Abstract:
Current cooling load prediction method of overall buildings for large-scale shopping malls cannot provide a reasonable control strategy for demands of various areas of the shopping mall. By studying the characteristics of cooling load in different areas of shopping malls, the key influencing factors of cooling load in different areas of shopping malls were screened by using grey relational degree analysis method. To solve the instability of the influence degree of each input variable on cooling load in actual situation, a short-term zoned cooling load prediction model based on double attention mechanism and LSTM was proposed. LSTM network fully considers the nonlinear relationship between air-conditioning cooling load and related characteristic variables. Feature attention analyzes the relationship between historical information and input variables autonomously to extract important features. Sequential attention selects historical information at critical moments of LSTM network to improve the stability of long-term prediction effects. The experimental results show that compared with LSTM model, CNN-LSTM model and attention-LSTM model, the error indexes MAPE and RMSE of the proposed model decrease significantly, and its R2 increases significantly and remains stable above 0.99, indicating good generalization ability and strong stability.

7 Current situation of landfill leachate production and treatment prospect in China

ZHANG Yanyan , ZHENG Zhihong , LIU Hongliang , FU Manqin , LI Lei , PENG Xuya

2023, 46(6):76-88. DOI: 10.11835/j.issn.1000-582X.2022.255

[Abstract](677) [HTML](74) [PDF 757.99 K](2363)

Abstract:
The disposal of leachate is highly valued by the government due to its characteristics of high concentration of pollutants and ecological risk. Based on literature survey, this paper investigated the output and pollution characteristics of different kinds of leachate from transfer stations, incineration plants and landfills. The development of leachate disposal technology and management was examined based on the current solid waste treatment policy. The results show that with the construction of “zero waste cities”, the difficulties in leachate disposal can be alleviated both in terms of quantity and quality with the implementation of policies such as garbage classification and “zero landfill” of crude waste, while middle and aged-landfill leachate has become the main target in the future. The technical mode of “pretreatment + biological treatment + advanced treatment” was applied as an effective means for leachate disposal. With the wide implementation of garbage classification, particular attention was given to local optimization in pre-treatment stage. The development of low carbon and carbon-free denitrification process can significantly achieve increased operational efficiency and consumption reduction during biological treatment stage. In the stage of advanced treatment, non-membrane full quantification treatment process was the main focus for proper disposal of concentrated leachate and trace organic compounds removal, which is helpful to achieve a more comprehensive risk control on leachate pollution.

8 Thermodynamic behavior and analysis of typical impurity elements in the roasting process of molybdenum concentrate

LIU Qihang , LIU Ruilin , YANG Shuangping , HE Kai , WANG Lidong

2023, 46(6):89-100. DOI: 10.11835/j.issn.1000-582X.2022.110

[Abstract](263) [HTML](81) [PDF 4.93 M](678)

Abstract:
The interaction between various impurity elements in the roasting process of molybdenum concentrate was studied by the simulation experiment combined with analysis techniques, including X-ray fluorescence spectrometry, inductively coupled plasma spectrometer and mineral liberation analyser. Based on the quantitative analysis of the phase by mineral liberation analyser, the thermodynamic conditions of the reaction of different impurity elements in the roasting process of molybdenum concentrate were analyzed by Factsage 7.0 software. The results show that there is obvious grain size segregation in the distribution of impurity elements in the molybdenum concentrate and subsequent treatment processes. The main findings are that impurities such as K and Si are more likely present in the coarse-grained molybdenum concentrate in the form of large-molecular-mass-minerals, while impurities such as Fe, Ca and Cu are more likely present in the fine-grained molybdenum concentrate in the form of small-molecular-mass compounds such as FeS₂, CaSO₄ and CuFeS₂. Impurities, such as FeS₂, CaSO₄ and SiO₂, form a dense mixture with MoO₃ during high temperature roasting, which reduces the leaching rate of Mo. Muscovite decomposes into syenite in the roasting process of molybdenum concentrate, and syenite transform with CaF₂ the fluxing medium into ions of metals, such as K and Al, that are soluble in water, and then is washed away. Therefore, reasonable control of molybdenum concentrate particle size and roasting conditions is an effective measure to reduce the impurity content in molybdenum products.

9 Neural network adaptive control of the robot joint with limited input

LEI Yuan , LI Cong , SONG Yankui , LI Junyang , WANG Sen

2023, 46(6):101-111. DOI: 10.11835/j.issn.1000-582X.2022.106

[Abstract](368) [HTML](44) [PDF 2.01 M](720)

Abstract:
An adaptive control method of input saturation command filtering based on radial basis function (RBF)neural network was proposed to solve the problems of limited control input, nonlinear friction, flexible deformation and unknown disturbance torque in the dynamic model of the robot joint. Based on the instruction filter backstepping method, the saturation function was used to constrain the amplitude of control input and the RBF neural network was used to approach the unknown disturbances. All the errors of the closed-loop system were proved ultimately uniformly bounded by using the Lyapunov stability theory. The simulation results show that the proposed control algorithm not only makes the control input amplitude of the system strictly constrained within the specified range, but also completes the high-precision tracking of the target trajectory (the tracking error is about ±0.003 rad). It can also resist the adverse effects of external step disturbance torque and modeling error on the control system, ensuring high accuracy and strong robustness of the system. The performance of the proposed control method is better than PID (propotional integral derivative) control and ordinary CFBC (command filter backstepping control) methods. It is of great value to the application and intelligent control of the robot joint in high precision field.

10 Material characterization and pore-scale simulation of PEMFC gas diffusion layer during its fabrication process

YANG Wangfan , YIN Zequan , ZHU Lijun , SHAO Qinsi , JUNG Chungyen , SUI PangChieh

2023, 46(6):112-121. DOI: 10.11835/j.issn.1000-582X.2023.06.010

[Abstract](322) [HTML](116) [PDF 3.59 M](921)

Abstract:
This paper reports the results of an investigation into the effects of fabrication techniques on the structure and performance of a gas diffusion layer (GDL) for proton exchange membrane fuel cells (PEMFC). In the experiment, GDLs were fabricated by hot-pressing, carbonization, and graphitization with polyacrylonitrile-based carbon fiber paper as the precursor and phenolic resin as the adhesive to bind the fibers. The effects of the mass fraction of phenolic resin solution on the structure and properties of GDL were investigated. The GDL microstructure was characterized by scanning electron microscopy, mercury intrusion porosimetry, and four-probe method. The structure of GDL was obtained by X-ray tomography, and pore-scale simulations were performed on the structure. The results show that GDL performance can be quantified accurately via experimental characterization and simulations. It is found that for a raw paper impregnated with 15% mass-fraction phenolic resin solution, a GDL with 78% porosity and 30% reduced resistivity can be obtained compared with commercial GDLs.

11 The influence of load condition on wheel-rail contact impedance based on ANSYS

SU Pengfei , TAN Li , WEN Run

2023, 46(6):122-129. DOI: 10.11835/j.issn.1000.582X.2023.06.011

[Abstract](260) [HTML](60) [PDF 1.46 M](789)

Abstract:
The burning accidents of insulation joints often occur in high-speed railway stations. The wheel-rail contact resistance is an important factor to cause the burning loss of insulation joints by wheel-rail arc. Therefore, accurate calculation of contact resistance is important for analyzing the burning loss of insulation joint. The level of the contact resistance mainly depends on the area of the wheel and rail contact spots. In this paper, first, the wheel-rail contact area under different working conditions was calculated by ANSYS. Then, the influence of the train axle load and offset on contact spot area was investigated. The results show that when axle load increased from 9 t to 27 t, the wheel-rail contact resistance decreased by nearly 36.2%. The wheel-rail contact resistance decreased by 18.9% when the lateral displacement increased by 10 mm. The change of wheel-rail contact resistance presented the same trend with the increase of axle load and wheel-rail contact resistance.

12 Evolutionary algorithm based biomedical ontology matching technique

WANG Ying , XUE Xingsi , LU Jiawei , HUANG Yikun

2023, 46(6):130-135. DOI: 10.11835/j.issn.1000.582X.2023.06.012

[Abstract](268) [HTML](48) [PDF 540.38 K](469)

Abstract:
Since biomedical ontologies own large-scale concepts and complex relationships among them, the existing ontology matching techniques are not able to determine the biomedical alignment efficiently. To tackle this challenge, a mathematical optimal model for biomedical ontology matching problem is first constructed, and then an evolutionary algorithm (EA) based biomedical ontology matching technique is proposed to determine the optimal alignment. In particular, when solving the biomedical ontology matching problem, a novel biomedical concept similarity measure is utilized to ensure the quality of the alignment, and a reasoning-based concept pruning approach is used to reduce the algorithm's search space and improve its efficiency. The experimental results show that EA-based biomedical ontology matching technique is able to match the biomedical ontologies effectively and efficiently.

13 A UAV nest deployment method with multi-target optimization and minimum cost

DAI Yongdong , HUANG Zheng , GAO Chao , WANG Maofei

2023, 46(6):136-144. DOI: 10.11835/j.issn.1000.582X.2023.06.013

[Abstract](484) [HTML](113) [PDF 2.08 M](1197)

Abstract:
In the unmanned aerial vehicle (UAV) inspection operation, heterogeneous UAVs often face coordination and nest site selection problems due to their different functions and range capabilities. The optimal deployment strategy of the UAV nest can be seen as a new type of location optimization problem. Compared with the traditional facility location problem, the deployment of the UAV nest is facing more new challenges. This paper comprehensively uses geographic information systems and TOPSIS method to pre-screen candidate locations, and then uses a combination of greedy algorithms and Lagrange relaxation optimization of the p-median coverage problem optimization method. After comprehensively considering factors such as node placement principles, flying tasks, flying radius, and functional redundancy, a multi-objective optimization lowest-cost UAV nest location method is proposed. The nest distribution problem is defined as a p-median problem with the lowest cost under pre-selected restricted factors, and principal constraints are set to achieve multi-objective optimization lowest-cost node placement and reduce inspection costs from multiple perspectives. The experimental results show that the cost savings of the nested distribution after multi-objective optimization are more than 9.2% compared with those of traditional methods in terms of construction, maintenance, inspection, and comprehensive costs.

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