Table of Content

25 May 2024, Volume 52 Issue 5

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2024, 52(5):  0. 

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Traffic & Transportation Engineering

Skid Resistance Deterioration and Influencing Factors of Ultra-Thin Wear Layer



WANG Duanyi, LI Yanbiao, PAN Yanzhu

2024, 52(5):  1-9.  doi:10.12141/j.issn.1000-565X.220806

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To accurately evaluate the decay process, mechanism and influencing factors of anti-sliding performance of asphalt ultra-thin wear layer after opening to traffic, this study first used arc mold and its supporting wheel grinding mechanism to prepare arc-shaped ultra-thin wear layer specimens. Then, it carried out the accelerated loading test of asphalt ultra-thin wear layer specimens with four gradation types and three asphalt binder grades by driving wheel accelerated loading system. Finally, it scanned the specimens after a certain number of wheel loads by laser texture scanner. Combined with the test data, the macro and micro structure depth decay models of asphalt ultra-thin wear layer based on S-type function were established respectively, and the independent and coupling effects of each porosity and asphalt binder on skid resistance were analyzed based on grey correlation analysis. The experimental results show that the driving wheel accelerated loading system combined with the S-type function model can quantitatively evaluate and predict the evolution process of the performance of the asphalt ultra-thin wear layer. The porosity affects the early decay rate of the macro and micro structural depth of the ultra-thin wear layer. The larger the porosity, the greater the early decay rate of the macro and micro structural depth of the ultra-thin wear layer. The middle and late decay rate of macro-structure depth is more affected by the grade of asphalt binder. The higher the performance grade of asphalt binder, the slower the decay rate of macrostructure depth in the middle and late stages. Void ratio and asphalt binder grade have similar influence on the decay rate of the micro-structure depth of the ultra-thin wear layer in the middle and late stage. Therefore, when designing the anti-sliding performance of the ultra-thin wear layer, it is beneficial to select the open-graded ultra-thin wear layer mixture with large porosity for the anti-sliding durability of the pavement, and the performance grade of asphalt binder can be reasonably selected according to the traffic volume.

Recognition Model of Highway Toll Evasion Behavior Considering Cost-Sensitivity



ZHAO Jiandong, XU Huiling, LÜ Xing, et al

2024, 52(5):  10-19.  doi:10.12141/j.issn.1000-565X.230078

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In order to effectively improve the efficiency of highway vehicle toll evasion inspection, based on ETC （Electronic Toll Collection） toll data, this paper proposed a highway vehicle evasion recognition model by combining KNN (K-Nearest Neighbor), adaptive boosting (Adaboost) algorithm and cost-sensitive learning mechanism. Firstly, in view of the large volume and redundancy of the original ETC toll flow data, data discretization and standardization processing rules were developed to repair and standardize the data form, and then two types of toll evasion features were extracted. Secondly, seven types of toll evasion, such as large vehicles with small tags, were selected as the main research objects by analyzing the ETC data set. Thirdly, to address the problem of inefficient model classification due to the “high-dimensional” characteristics of the evasion data, the best subset of features showing the evasion characteristics was selected by Pearson and Spearman correlation analysis and ReliefF importance analysis. Fourthly, to address the model overfitting problem caused by the class “imbalance” between toll evasion vehicles and normal vehicles, KNN was used as the base classifier in the Adaboost algorithm, and the boundary ambiguity of different categories was alleviated through TomekLinks undersampling, then a cost-sensitive learning mechanism was introduced to improve the model’s emphasis on the minority class (toll evasion vehicles) to alleviate the tendency to discriminate the majority class (normal vehicles). Finally, the performance of the KNN-Adaboost model incorporating cost-sensitive learning mechanisms was verified by comparing the recognition effects of different classification models for various types of evasion events. The results show that the precision of the proposed model is 0.98, Recall is 0.96, F1-score is 0.97, and Kappa coefficient is 0.95, indicating that the proposed model can better solve the sample class imbalance problem than other models and has higher recognition accuracy for minority class，and it can be a reference for improving the efficiency of highway toll inspection.

Optimization Design of the Stereoscopic Compound Expressway Sign System Based on Unity3D



GAO Longkai, ZHAO Xiaohua, OU Jushang, et al

2024, 52(5):  20-30.  doi:10.12141/j.issn.1000-565X.230263

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By adding bilateral elevated layers, the renovation and expansion of the expressway have improved the traffic capacity, but a subsequent rise in problems, such as insufficient spacing, excessive traffic volume, and multi-diversion, has made the existing traffic signs fail to meet the drivers’ guidance needs. In response to this issue, this study took the Ji-He Expressway in Shenzhen as an example and designed four optimized traffic sign schemes of interchange based on the conventional standard scheme, and developed the corresponding stereoscopic compound expressway scenes by the Unity3D engine. The vehicles on the expressway will drive out of the ground-level road at the first diversion, enter the elevated-level road at the second diversion, and connect to other expressways at the third diversion. 28 drivers simulated driving in different scenes using external interactive devices, and their driving behavior data such as speed, acceleration, lane position, etc., were obtained. By calculating the point-by-point significance of indicators within each affected section in different guidance sign design schemes, differences in spatial dimensions of each indicator were presented, and further analysis shows that 3 km warning signs can help drivers perceive the situation of the ramp ahead as early as possible. Lane guidance signs can improve the longitudinal and lateral stability of vehicles at the ramp, and drivers can take better lane changing strategies. Navigation voices assistance can improve the driver’s speed control proficiency, lane changing awareness of expressway exits, and psychological comfort at the interchange of stereoscopic compound expressway. The research shows that Unity3D has high fidelity, good interactivity, and low cost, and it can provide technical support for relevant research on driving behavior in complex road scenes in the future. At the same time, this study also provides a theoretical reference for the establishment of traffic guidance signs in expressway renovation and expansion projects.

Coupling Analysis of Rail Transit Stations’ Network Centrality, Ridership and Spatial Heat Map



WU Jiaorong, CHEN Caiting, DENG Yongqi

2024, 52(5):  31-42.  doi:10.12141/j.issn.1000-565X.230302

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Urban spatial heat map reflects population aggregation and street vitality. In order to explore the interactive relationship between urban rail transit and spatial heat map, this study used Baidu heat map and rail transit station ridership data to analyze the coupling characteristics between network centrality, ridership and nearby spatial heat index of rail transit stations on a micro level, taking Shanghai as a case study. Firstly, it investigated the overall coupling relationship between two categories of station attributes and spatial heat through Pearson bivariate correlation analysis. Then, bivariate spatial autocorrelation and geographically weighted regression analysis methods were introduced to explore the spatial association patterns between network centrality and spatial heat, as well as between spatial heat and ridership, followed by a spatial differentiation comparison between the two coupling types. The results show that the coupling relationship between rail network centrality and spatial heat is obviously better than that between ridership and spatial heat at station level, since traffic location advantage can usually develop higher spatial heat, while ridership may be affected by more complex factors. Spatial heat map is more suitable for quantifying the interaction between rail transit and urban space in areas outside the urban core, where increasing rail network centrality has a multiplier effect on spatial heat improvement, but improving spatial heat in areas with low-density development is more conducive to stimulating ridership. It is feasible to evaluate the ridership potential of new stations outside the urban core area by using spatial heat map, but this data alone is not enough to predict ridership. The urban renewal around rail transit stations can be optimized by referring to the differences between the two types of coupling at different spatial locations. This study explored the analytical framework for improving the layout of rail transit network based on urban spatial heat map, and optimizing TOD (Transit-Oriented Development) stations for factors negatively affecting their coupling. It provides a new perspective for measuring the man-land relationship of urban rail transit on the micro level.

On the Nonlinear Relationship Between Land Use and Urban Rail Transit Passenger Flow



WEI Liying, SHI Jingjing

2024, 52(5):  43-51.  doi:10.12141/j.issn.1000-565X.230125

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The impact of land use on passenger flow within the influence scope of urban rail transit stations has different spatiotemporal differentiation characteristics. To explore the complex nonlinear relationship between land use and passenger flow at different stations, this paper proposed a differentiation identification method based on the spatial distribution of land use variables, and through time-phased multiscale geographic weighted regression, station clustering indicators that can characterize the spatiotemporal changing characteristics of land use impact on passenger flow were obtained. K-means++ algorithm was used to divide the stations into four categories, and the complex nonlinear relationship between land use and railway passenger flow under different categories was explored based on the improved gradient boosting decision tree model. Research shows that the accuracy of nonlinear model can be effectively improved by capturing the spatiotemporal heterogeneity of the relationship between the land use and passenger flow and classifying the stations properly. According to the output results, the key factors are different for each category. For the first category, the bus station number and sidewalk density have top relative importance value of 61.35% and 30.08% respectively; the key factors are the same for the fourth, but with an importance value decreasing from 61.35% to 30.31% for the bus station number. For the second category, the building densityhas the greatest impact with a relative ratio of 66.57%, and on the contrary, which only accounts for 5.59% for the third one. Meanwhile, there are significant and varying threshold effects on the relationship between land use and rail transit passenger flow. The result shows that different types of stations should put different emphasis on land use development, and land use design indicators should be controlled within a reasonable range. This research will provide theoretical support and quantitative guidance for the formulation of differentiated land use development strategies around stations.

Adaptive Fuzzy Tracking Control of Unmanned Surface Vehicle with State and Input Quantization



NING Jun, MA Yifan, LI Wei, et al

2024, 52(5):  52-61.  doi:10.12141/j.issn.1000-565X.230215

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An adaptive feedback tracking control scheme with state and input quantization was designed for the track tracking control problem of unmanned unmanned surface vehicle under the restricted communication bandwidth at sea. While ensuring effective tracking, it reduces the burden of maritime communication signal transmission, decreases the actuator execution frequency and reduces the control amplitude. Firstly, the system control law was designed based on the adaptive backstepping method, which combined with the dynamic surface technology to effectively reduce the computational inflation problem of the virtual control law. For the uncertain terms existing in the control system, a fuzzy logic system was used for approximation. Next, the state variables and input variables in the control system were quantized separately using a uniform quantizer, and the quantized state feedback information was used in the design of the unmanned surface vehicle track tracking controller. Based on the obtained quantization information, a control law for tracking the trajectory of an unmanned surface vehicle was proposed under the conditions of simultaneous consideration of state and input quantization. The boundedness of the errors between quantized and unquantized variables in the closed-loop control system was demonstrated by a recursive approach. The stability of the designed fuzzy adaptive feedback tracking control system with state quantization and input quantization was demonstrated based on Lyapunov stability theory when both state quantization and input quantization were considered. Finally, the effectiveness of the proposed scheme is verified by two sets of simulation experiments. That is, under the simultaneous consideration of state quantification and input quantification, the unmanned surface vehicle can still maintain a good tracking performance of the ideal trajectory, and effectively reduce the execution frequency of the actuator, which is more in line with the practice of navigation engineering.

Floating State Calculation Method of Multi-Convex Structure Considering the Influence of Free Liquid Level



LIU Xiao, ZHOU Quan, FAN Tianhui, et al

2024, 52(5):  62-70.  doi:10.12141/j.issn.1000-565X.230192

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In view of the influence of free surface in tank on floating state and stability, this paper proposed a new floating state algorithm of multi-convex composite structure. The floating body and the liquid tank were decomposed into multiple tetrahedral elements, and then the buoyancy and center of buoyancy of the floating body and the center of gravity of the liquid tank were determined by analyzing the relative position of each tetrahedron and the water surface/liquid surface. An improved double iteration method was also proposed to determine the floating state of multi-convex composite structures: the inner iteration method was used to simulate the heaving motion of the floating body to obtain the water/liquid surface equations outside the floating body and inside the tank; the rotation motion of floating body was simulated by outer iteration. The two iterative methods were carried out alternately until the distance between the gravity action line and the buoyancy action line of the floating body meets the accuracy requirement, and the gravity is equal to the buoyancy force. The study calculated the floating state of a semi-submersible vessel and a semi-submersible offshore platform under various typical working conditions using self-compiled program, and the influence of free surface was also considered. In addition, MAXSURF modeling was used for comparative analysis, and AUTOCAD was used to verify the accuracy. The results show that: (1) the algorithm can take into account the influence of free surface on floating state with clear principle and good convergence; (2) the algorithm is easier to obtain accurate solutions for both traditional single-convex structures (such as single hull vessel) and multi-convex structures (such as multi-hull vessel, floating offshore platform, etc.), and its computational efficiency is higher; (3) the algorithm can realize the “building-block” modeling mode, which can greatly reduce the workload in multi-condition modeling; (4) the algorithm does not need to rely on foreign third-party graphics platform (such as AUTOCAD, CATIA) , which lays a good foundation for the localization of related industrial software in our country.

Architecture & Civil Engineering

Formation Factor Analysis and Evaluation Model Construction of Mud Cake on EPB Cutterhead



DING Xiaobin, YANG Huitai, SHI Yu

2024, 52(5):  71-83.  doi:10.12141/j.issn.1000-565X.230385

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Focusing on individual factors，the current research on the mud cake formation of earth pressure balance (EPB) tunnel boring machines (TBMs) lacks a comprehensive and quantitative evaluation standard and can’t meet the predictive needs of TBM mud cake in engineering. Addressing these issues, this paper systematically summarized 23 key factors contributing to the formation of mud cake of EPB TBMs from three aspects: geological conditions, TBM selection, and construction factors. The mud cake risk during the excavation process of EPB TBMs was classified into four levels: high, medium, low, and no risk. Simultaneously, the paper proposed a quantitative standard for mud cake risk factors and constructed a risk evaluation model for the mud cake of EPB TBMs utilizing the analytic hierarchy process (AHP). Based on excavation data from the Ma-Chuang section, right tunnel of Line 14 of the Guangzhou Metro, the mud cake risk levels for different tunnel rings during TBM excavation were calculated, validating the predictive performance of the mud cake risk evaluation model. Research results indicate that among the 23 influencing factors in the mud cake risk evaluation model, the plasticity index, cutterhead torque, liquidity index, and total thrust have the highest impact weights, while the startup torque has the lowest impact weight. The mud cake risk evaluation model demonstrates excellent predictive performance, with the calculated mud cake risk variation curve closely matching on-site construction conditions. Changes in TBM excavation parameters effectively reflect the formation of mud cakes during excavation, with total thrust being the most sensitive, followed by cutterhead torque, chamber pressure, advance speed, and screw conveyor speed in decreasing order of sensitivity. The research results can be applied to the evaluation and analysis of mud cake formation by EPB TBM cutterheads in similar engineering projects.

Analytical Solution and Simplified Solution of Two-Dimensional Steady Seepage Field in Foundation Pit



YU Jun, ZHENG Jingfan, ZHANG Zhizhong, et al

2024, 52(5):  84-91.  doi:10.12141/j.issn.1000-565X.230075

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In foundation pit engineering, groundwater seepage significantly impacts pit stability, yet current one-dimensional seepage theory doesn’t fully meet safety standards for seepage calculation. This study addresses these gaps by analyzing two-dimensional seepage in isotropic soil layers under suspended support, disregarding retaining wall thickness. The water head in each of the four regions was expressed in the form of a series solution by using the superposition principle and the separation of variables method, and the analytical solution of the seepage field was obtained by combining the continuity conditions between the regions and the orthogonality of the series solution. Comparing this analytical solution with PLAXIS 2D software results, it finds that a series term of 20 provides convergence, while a single term still maintains accuracy, representing exact and simplified solutions respectively. The simplified solution offers easy calculation, providing quick determination of water head at any point in the pit. Comparing the calculation results of one-dimensional water pressure, one-dimensional water pressure considering seepage, flow network method, simplified solution, exact solution and numerical solution, it is found that the exact solution is in better agreement with the numerical solution and has higher accuracy than the flow network method, and the simplified solution has higher accuracy than one-dimensional hydrostatic pressure and one-dimensional water pressure considering seepage. Parameter analysis reveals that relative error between accurate and simplified solutions for resultant water pressure is influenced by inner water level and distance from retaining wall to impermeable layer. The simplified solution is suitable for foundation pits of small dimensions, especially when the distance from the inner water level to the bottom of the retaining wall is greater than 7 meters and the distance from the bottom impermeable layer to the retaining wall is less than 30 meters. The calculation of the point of application of the retaining wall water pressure resultant force is suitable for foundation pits of any size. Compared with the accurate solution, the error of the simplified solution mainly occurs at the bottom of the retaining wall, while at other locations, the head error is less than 5% for small-sized foundation pits.

Fatigue Cracking Characteristics of Butt Welds in U-Rib Embedded Section of Steel Bridge Decks



JIANG Xu, LÜ Zhilin, QIANG Xuhong, et al

2024, 52(5):  92-100.  doi:10.12141/j.issn.1000-565X.230071

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As one of the typical fatigue details of the steel box girders, the U-rib butt weld in the embedded sections of the steel bridge decks is prone to fatigue cracking under the repeated action of the wheel load, and it directly affects the safe operation and durability of the bridge structures. In order to explore the fatigue cracking characteristics of U-rib butt weld on the roof of the orthotropic steel bridge decks, this paper first established a local model of the steel bridge deck using finite element simulation, and studied the fatigue stress characteristics of the U-rib butt welds in the embedded sections. Then it designed four full-scale single U-rib specimens and carried out a fatigue performance analysis of the actual structure combing with fatigue test. On this basis, the modified main S-N curve suitable for fatigue life prediction of U-rib butt welds was proposed by the structural stress method, and the fatigue crack propagation behavior of weld detail was explored based on the extended finite element method (XFEM). The results show that the longitudinal influence range of U-rib butt weld stress under the wheel load is two cross-spacer spacing, and the lateral influence range is 1.5 U-rib spacing. The arc transition area is subjected to the greatest fatigue stress amplitude and high stress concentration, which becomes a potential fatigue vulnerable point. The fatigue cracks observed in the experiment all start at the arc transition and continue to extend to the bottom edge of the longitudinal rib and the web. Based on the evaluation of the nominal stress method, the average fatigue strength of the welds is 68 MPa, which is close to the 71 MPa specified in the European Code. Compared with the main S-N curve proposed based on the equivalent structural stress method, the modified main S-N curve proposed in this research is safer and more conservative for fatigue life prediction. The extended finite element method can effectively simulate the expansion behavior of U-rib butt welds. Both fatigue tests and XFEM results indicate that the fatigue crack propagation direction depends on the location of the initial defect. When the initial defect appears on the bottom plate, fatigue cracks tend to extend along the bottom plate; but when the initial defect is located on the web plate, fatigue cracks tend to extend along the web.

Axial Compression Behavior of Rectangular Concrete-Filled Steel Tube Columns Reinforced by Built-In Profiled Stirrup



KANG Lan, CHEN Xuan, HONG Shutao

2024, 52(5):  101-113.  doi:10.12141/j.issn.1000-565X.230116

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Concrete-filled steel tube (CFST), as a kind of structure with broad development prospect, has good bearing capacity and plastic deformation ability. As a common form, rectangular concrete-filled steel tube column is widely used in engineering practice. Based on the two problems of inconsistent constraints on long and short sides and insufficient constraints on core concrete existing in practical application of rectangular concrete-filled steel tube, this study explored a new type of rectangular concrete-filled steel tube member, namely rectangular concrete-filled steel tube column reinforced by built-in profiled stirrup. Therefore, this study carried out the axial compression tests on 11 rectangular concrete-filled steel tube columns reinforced by built-in profiled stirrup, 2 rectangular concrete-filled steel tube columns with built-in racetrack stirrup, and 2 ordinary rectangular concrete-filled steel tube columns. It analyzed the influences of the coupling distance, steel tube thickness, concrete strength grade, stirrup spacing, stirrup diameter, built-in steel quantity on the axial compression bearing capacity and ductility of rectangular concrete-filled steel tube columns reinforced by built-in profiled stirrup. The findings reveal that reducing the thickness of the rectangular steel tube and embedding the resulting steel into the core concrete as profiled stirrup can effectively improve the axial compressive bearing capacity and ductility of the specimen, while maintaining the total amount of steel used. Additionally, the axial compression behavior of rectangular concrete-filled steel tube columns reinforced by built-in profiled stirrup can be divided into four stages: elastic stage, elastoplastic stage, plastic strengthening stage, and descending stage. Compared to ordinary rectangular concrete-filled steel tube columns, those reinforced by built-in profiled stirrup exhibit a more complete plastic strengthening stage. Based on the experimental results and parametric analysis, this study derived a calculation formula for the axial bearing capacity of rectangular concrete-filled steel tube columns reinforced by built-in profiled stirrup using an existing confined concrete constitutive model. This study can provide scientific basis and data reference for practical engineering applications.

Shear Strength Calculation of RC Beams Without Shear Reinforcement Based on Crack Sliding Model



GONG Zhongwen, XIONG Ergang, WANG Wenxiang, et al

2024, 52(5):  114-126.  doi:10.12141/j.issn.1000-565X.230238

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In order to investigate the effect of flange on the shear capacity of reinforced concrete (RC) beams without stirrups, this study took into the contribution of compression zone, dowel action, and aggregate interlock in tension zone, and proposed a shear capacity calculation formula for RC beams without stirrups based on the crack sliding model. To verify the accuracy of the formula, the study used the formula and major design codes to calculate the collected experimental data of 444 rectangular beams and 172 T-shaped beams, and the results were compared with the results of major design codes. Five commonly used machine learning algorithms were used for regression analysis on the collected dataset, to verify the fit of each algorithm with a small dataset to analysis on the collected data, and the fitness of each algorithm was validated with a small dataset.The results show that: the shear capacity calculation method proposed by the codes of each country is in good agreement with the test results; compared to the calculation of the codes, the addressed calculation method herein is more accurate and can effectively account for the contribution of the T-beam flange to the shear capacity; the five machine learning models selected in this paper exhibit a desirable accuracy on the test set, and the results show the same trend as calculations; it also demonstrates the applicability of the machine learning models in the calculation of the shear capacity for reinforced concrete beams.

Investigation into Creep Properties of Kapton Films Under Different Initial Stresses



LIU Yan, XUE Xinyuan, FAN Lei, et al

2024, 52(5):  127-138.  doi:10.12141/j.issn.1000-565X.230168

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As a kind of aerospace membrane material, polyimide film’s (Kapton film) creep effect is very important to its structure. In order to study its creep mechanical properties, firstly the study selected Kapton film with a thickness of 25 μm, and carried out the uniaxial creep tensile test under the four stress levels of 35%, 50%, 65% and 80% of the ultimate tensile strength. Secondly, according to the creep mechanics curves obtained, the creep characteristics of the film under different initial stresses were analyzed, and the intrinsic mechanism was discussed by combining the creep elongation. Five creep constitutive models of classical Kelvin, classical Maxwell, four-element Burgers, three-parameter generalized Kelvin and five-parameter generalized Kelvin were used to fit the experimental data, and the fitting effects of each model were compared and analyzed. The results show that Kapton film has obvious viscoelastic properties, which should be considered in the design. The initial stress has a significant effect on the creep properties of Kapton film. The greater the initial stress, the higher the strain at the initial creep stage, the higher the strain retention value at the steady creep stage, and the more obvious the viscoelasticity is. The tensile fracture stress levels in different directions lead to the differences of creep properties, and the total strain of TD (Transverse Direction) is greater than that of MD (Machine Direction) under each stress state. With the increase of the initial stress, the creep elongation of the film first increases and then decreases. This is because the influence of the initial stress on the stress state and dislocation motion inside the film is complex, and there is an equilibrium point. The five-parameter generalized Kelvin model adopted in this paper can well predict the creep properties of Kapton film, and the coefficient of determination of the fitting results is more than 0.99, followed by the Burgers model. The fitting coefficients of classical Kelvin, three-parameter generalized Kelvin and classical Maxwell model are between 0.71 and 0.86, and the fitting results meet the needs of practical engineering.

Multi-Variable Coupled Physical Model of Water-Cooled Centralized Air-Conditioning Cold Source System



LIU Xuefeng, HUANG Bin, DING Liwei, et al

2024, 52(5):  139-152.  doi:10.12141/j.issn.1000-565X.230085

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The water-cooled centralized air-conditioning system is a multi-variable coupled nonlinear system with a high degree of sparsity in operational data, leading to poor generalization ability of data-driven machine learning models. A comprehensive physical model reflecting the hydraulic and heat transfer mechanisms has become a key focus of current research. However, there are some technical challenges that urgently need to be addressed, such as the complexity of variable coupling in the system, nested iterations leading to significant computational costs, and that changes in hydraulic structure due to equipment start-stop cycles necessitate frequent model reconstructions. By using continualization of discrete variables and pattern search methods to correlate resistance coefficients with branch openings, and equipment start-stop events with pump operating frequencies, it is possible to integrate discrete variables into continuous ones, reduce nested iterations, and achieve dynamic flow distribution and global hydraulic-thermal coupling calculations. This study established a multi-variable coupled physical model of a water-cooled centralized air-conditioning cold source system with external constraints such as cooling load, chilled water flow rate, chilled water supply temperature, chilled water supply-return pressure difference, and ambient temperature and humidity, enabling asynchronous adjustments of multiple independent variables including the number of chiller units, the number of chilled water pump units and frequencies, the number of cooling water pump units and frequencies, and the number of cooling tower units and frequencies. The reliability of the model was validated through a comprehensive experimental platform to explore the operational characteristics and group control strategies of chiller units, cooling towers, chilled water pumps, and cooling water pumps under different operating conditions. The research findings indicate that the simulation results of the cold source system physical model have an average relative error of less than 10%, with a few cases within 15%. The computational time for a single iteration is approximately 0.32 s. The adjustment of multiple variables can comprehensively balance the energy efficiency of each subsystem. Global optimization of the system can maximize energy-saving opportunities, addressing the shortcomings of traditional subjective empirical control in maintaining stable energy-saving effects and providing a theoretical basis for intelligent diagnostics.