Abstract:To address the issues of unbalanced load and system nonlinearity in quadrotor unmanned aerial vehicles(UAV)attitude control,a LSTM-MPC strategy is proposed by combining the advantages of long short-term memory(LSTM)neural network and model predictive control(MPC).LSTM neural network is used to predict attitude changes,enhancing the system's ability to anticipate errors.MPC is employed as feedforward control to dynamically optimize control inputs.The combination significantly improves system control accuracy.MATLAB simulation experiment on quadrotor UAV attitude control with unbalanced load shows that:compared to MPC strategy,the LSTM-MPC strategy reduces the root mean square error of tracking expected values for roll angle,pitch angle,and yaw angle by 13.33%,12.31%,and 11.11%respectively;compared to fuzzy PID strategy,it reduces by 14.05%,25.33%,and 23.81%respectively.Flight test is conducted using a branded F450 quadrotor UAV platform carrying a 0.6 kg load to test unbalanced load attitude control.The test result shows that the average errors between the actual output and expected values of the quadrotor UAV's roll,pitch,and yaw angles using the LSTM-MPC strategy are 3.91%,5.31%,and 1.10%,respectively,indicating that the LSTM-MPC strategy can effectively improve the flight stability of quadrotor UAV attitude control with unbalanced load.

Abstract:To improve the comprehensive road performance of in-situ recycled asphalt mixtures,this study investigates the impact of the amount of rejuvenator on the performance of recycled asphalt based on rheological performance parameters such as rutting factor,creep stiffness,creep rate,and critical temperature difference.It proposes a method for determining the quality ratio of rejuvenator to reclaimed asphalt based on the relationship between continuous high-temperature grades and continuous low-temperature grades.This method balances the high-temperature and low-temperature performance of asphalt to define the quality ratio of rejuvenator to reclaimed asphalt.Based on the determined quality ratio,asphalt mixtures are prepared,and the high-temperature and low-temperature performance of these mixtures is compared with those determined by the penetration method for the same quality ratio of rejuvenator to reclaimed asphalt.The results indicate that as the quality ratio of rejuvenator to reclaimed asphalt increases,the rutting factor of recycled asphalt measured by dynamic shear rheology gradually decreases,the creep stiffness measured by bending beam rheology decreases,the creep rate increases,and flexibility improves.The quality ratio of rejuvenator to reclaimed asphalt determined based on continuous high-temperature and low-temperature grades results in a slight decrease in the high-temperature performance of the recycled asphalt mixture,but the water-saturated Marshall residual stability increases by 9.4%,the freeze-thaw splitting tensile strength ratio increases by 7.9%,and the bending failure strain of the small beam increases by 5.5%,effectively balancing the high-temperature and low-temperature performance of the recycled asphalt mixture.

Abstract:To analyze the coupling coordination development level between low-carbon logistics and regional economy in Shandong Province,a multidimensional evaluation index system for low-carbon logistics and regional economy is constructed.The entropy weight method and a coupling coordination degree model are employed to assess the comprehensive development levels of low-carbon logistics and regional economy and their coupling coordination degree in Shandong Province from 2014 to 2023,identifying key factors influencing their coordinated development.Results indicate that the comprehensive development levels of both low-carbon logistics and regional economy in Shandong Province continuously increase from 2014 to 2023,with the low-carbon logistics composite score rising from 0.066 3 to 0.912 6 and the regional economy composite score growing from 0.032 1 to 0.994 6.The coupling coordination degree increases from 0.215 to 0.976,transitioning from moderate imbalance to primary coordination and further to high-quality coordination.The order degree of regional economy and low-carbon logistics shows a significant positive correlation,reflecting a highly synergistic interaction mechanism with sustained positive coordination trends.The main constraints for coordinated development are ecological level and industrial structure.Shandong Province can achieve low-carbon transformation of logistics and high-quality development of the regional economy by optimizing transport networks,promoting energy structure transition,advancing green logistics technologies,and developing low-carbon agriculture.

Abstract:To investigate the shear strength and electrical resistivity characteristics of cement-stabilized soil under varying moisture contents,specimens were prepared with moisture contents of 7.7％,9.7％,11.7％,13.7％,15.7％,17.7％,and 19.7％,and a fixed cement content of 8％.Direct shear tests were conducted under vertical pressures of 100,200,300,and 400 kPa to examine the variation patterns of shear strength and resistivity responses under both unconfined and confined conditions.The results indicate that under unconfined conditions,both cohesion and internal friction angle at different moisture contents exhibit quadratic relationships with the initial resistivity.The fitted curves show high coefficients of determination,confirming the feasibility of assessing shear strength based on resistivity measurements.A nearly linear correlation is observed between shear strength and failure resistivity,where shear strength decreases as failure resistivity increases.With increasing vertical pressure,the peak shear stress of the specimens generally increased.As the moisture content increased,the peak shear stress first increased and then decreased.Under confined conditions,both initial and failure resistivity values exhibited negative exponential relationships with moisture content.As the vertical stress increased,the degree of reduction in failure resistivity decreased across different moisture contents.Under different moisture contents,the failure resistivity of the specimen generally decreases with increasing vertical pressure.

Abstract:To address the issues of settlement control,slope stability,and ecological protection during the construction of highways on soft soil foundations adjacent to rivers,based on the actual engineering case of the sixth section of the Tianjin-Shijiazhuang Expressway,a pile-net-filtering collaborative theoretical model is established.The model employs a pile-net structure formed by prestressed high-strength concrete(PHC)piles and reinforced cushion layers,combined with a new scheme for filtering concrete slopes,and is compared with traditional methods.The research results indicate that the new scheme effectively improves the bearing capacity of the foundation and the stability of the subgrade,with post-construction settlement not exceeding 52 mum(37％less than traditional methods)and differential settlement less than 2.0 mm/m;the filtering slope reduces pore water pressure by 55.6％,and the safety factor increases by 14.4％compared to traditional slope protection schemes;the life-cycle cost is reduced by 19.6％,construction time is shortened by 66.7％,carbon emissions are decreased by 27.6％,suspended particulate matter emissions are reduced by 78.2％,and the pH value returns to neutral(7.6).This scheme effectively resolves the three major conflicts of bearing capacity-settlement,water flow-soil interaction,and construction window limitations,providing an efficient,stable,and environmentally friendly solution for similar soft soil foundation projects adjacent to rivers.

Abstract:To analyze the traffic safety situation in complex navigable waters and assess the risk of vessel collisions,this study integrates multi-source data resources such as the automatic identification system(AIS)for vessels,port spatial distribution,and geographic information.The focus of the research is on the Pearl River Estuary,where the distribution of vessel types,sizes,and speeds in this water area is statistically analyzed.Geographic information data is utilized to analyze the spatial layout characteristics of the ports in this area.The navigation routes are divided into 24 time periods,and the water area is segmented into 9 parts.Based on line density analysis,the spatial characteristics of traffic flow and route distribution in the water area are studied,and the collision risk of vessels in key maritime traffic safety areas of the Pearl River Estuary is calculated and visualized.The results indicate that the vessel types in the Pearl River Estuary are diverse,with large sizes and high speeds;the main outbound navigation route from Guangzhou Port,the secondary outbound route from Guangzhou Port to the Dagang outbound route(passing through Lujing Bay),and the Shunde waterway to the Liansha Rong waterway are the three major routes,while the others are general routes.During different time periods,Route 3 has the highest number of routes,while Route 5 has the least.Route 3 is bimodal,with a higher number of vessels navigating during the noon and nighttime.Routes 2,4,6,and 7 are unimodal,and Routes 1,5,8,and 9 are stable regions with no significant peaks or troughs and little variation.In Route 3,the distribution of collision risk among vessels varies significantly,with higher collision risks present at the intersections of public channels and in the turning areas of the public channel.

Abstract:To study the stability of industrial sugarcane residue(mass fraction of 1.2％)-low alkali ecological cement(mass fraction of 7.0％)improved expansive soil slopes(hereinafter referred to as improved expansive soil slopes)under rainfall conditions,this research analyzes the differences between improved and unimproved expansive soils slope,as well as the intrinsic relationship between slope stability,deformation,and seepage.Based on soil parameters obtained from laboratory tests,numerical simulation software COMSOL Multiphysics is used to conduct large-scale slope rainfall intensity reduction simulations to explore the changes in effective saturation,plastic strain,displacement,and slope stability coefficient of the two types of soil slopes during rainfall.The results show that:1)After continuous rainfall,the overall change in effective saturation of the two types of soil slopes is small,with the effective saturation of the improved expansive soil slope greater than that of the unimproved expansive soil slope;under the condition of considering only the influence of rainfall,the effective saturation of the surface layer of the improved expansive soil slope at failure is greater than that of the unimproved expansive soil slope.2)Under rainfall conditions,plastic deformation in the unimproved expansive soil slope mainly occurs at the toe,while the plastic strain in the improved expansive soil slope concentrates at the crest,with the plastic strain of the improved expansive soil slope slightly larger than that of the unimproved expansive soil slope.3)After rainfall,displacements in both types of soil slopes occur at the crest,with the displacement of the unimproved expansive soil slope being about twice that of the improved expansive soil slope;within a relatively large displacement range,the area of affected soil in the unimproved expansive soil slope is larger,while the affected range of the improved expansive soil slope is limited to within 50 m around the plastic deformation,with the displacement of the unimproved expansive soil slope extending to the toe.4)Considering the rainfall intensity reduction method,U-shaped plastic strain zones appear within both types of soil slopes,with relative sliding occurring between the surface soil and deep soil;the plastic strain in the unimproved expansive soil slope is about three times that of the improved expansive soil slope;the stability coefficients of the unimproved expansive soil slope and improved expansive soil slope are 1.12 and 1.14,respectively,with the maximum displacement of the unimproved expansive soil slope being about four times that of the improved expansive soil slope.

Abstract:To investigate the effects of vehicle dynamic loads on the settlement and mechanical performance of the underground comprehensive utility tunnel in silty soil foundations,a calculation model of the buried comprehensive utility tunnel is established using the finite element software PLAXIS 3D,and a scaled model test is conducted to verify the reliability of the numerical model.By applying a sinusoidal wave to simulate vehicle dynamic loads,the influences of parameters such as tunnel burial depth,elastic modulus of backfill soil,groundwater level,vehicle load amplitude and loading position on the settlement and dynamic response of the tunnel are analyzed.The results show that:1)The settlement at each measurement point significantly increases within the first second,followed by periodic oscillation and stabilization,with the settlement of the soil at the bottom of the tunnel being less than that without the tunnel.2)The tensile stress in the tunnel is mainly concentrated on the inner side of the top slab of the left chamber,the upper outer side and the middle inner side of the left side wall,and the middle inner side of the right side wall,with the maximum tensile stress peak occurring on the upper outer side of the left side wall and the largest fluctuation amplitude generated on the inner side of the top slab of the left chamber.3)The vibration acceleration response of the top slab is larger,as it transmits the vibration acceleration response along the tunnel side walls and the central diaphragm to the bottom slab,with the top slab and side walls stabilizing around the second second,and the bottom slab stabilizing around the first second;after stabilization,the peak vibration acceleration of the top slab is the largest,while that of the bottom slab is the smallest.4)As the burial depth of the tunnel increases,the settlement of the soil at the bottom of the tunnel decreases,and the peak vibration acceleration of the top slab,side walls,and bottom slab decreases,with a recommended burial depth of 2.5 m to 3.0 m;as the vehicle load amplitude increases,the peak tensile stress,settlement,and peak acceleration of the tunnel all increase;the vehicle load applied directly above the comprehensive utility tunnel is the most detrimental to the tunnel,resulting in the maximum peak tensile stress and acceleration,while moving the loading position away from the tunnel's central axis to the left or right generally reduces the peak tensile stress and vibration acceleration of each structure of the tunnel.5)An increase in the elastic modulus of the backfill soil helps to reduce the settlement and peak acceleration of the tunnel.With the increase of groundwater level,the settlement at the bottom of the tunnel initially decreases slightly and then increases.

Abstract:To analyze the actual working performance of the large-span cast-in-place concrete beam combined supporting system,to prevent support overturning accidents during construction,and to optimize structural redundancy design,a monitoring system is established based on the Jinan tram project's three-span continuous beam bridge by deploying high-precision sensors.A method combining real-time monitoring throughout the construction process with finite element simulation is used to study the key mechanical behaviors of the combination system composed of steel pipe columns,Bailey beams,and buckle supports.The results indicate that during the entire construction process,the stress monitoring results of the main components of the combined support system are generally 5％to 15％lower than the finite element calculation results,suggesting that the overall design of the combined support system based on finite element simulation possesses a higher safety reserve;the stress monitoring results of the upper chord member of the Bailey beam at mid-span showed a significantly greater discrepancy compared to the finite element results than the lower chord member at mid-span,indicating that there is a deviation between the internal constraints of the finite element model and the actual working conditions;the stress monitoring results of the diagonal braces between the steel pipe columns are greater than the finite element simulation results,which should be noted during the design phase.

Abstract:To improve vehicle-cargo matching efficiency on online freight platforms,a three-stage supply-demand matching model is proposed that accounts for the needs of carriers,shippers,and the platform.Stage 1 constructs a cargo attribute classification model to identify and eliminate conflicts among different cargo attributes.Stage 2 develops a vehicle information screening model to extract each vehicle's high-frequency delivery regions.Stage 3 formulates a multi-objective matching model with objective functions that maximize carrier profit,minimize shipper cost,and maximize platform revenue.A traditional genetic algorithm is enhanced with a greedy operator,a circle chaotic map,an opposition-based learning strategy,and a simulated annealing mechanism,and the enhanced algorithm is used to solve the model.An empirical analysis is conducted using Guangzhou-origin freight and vehicle postings released by the China Wutong Network.The results indicate that the matching solutions obtained with the improved genetic algorithm outperform those from the standard genetic algorithm in overall loading efficiency and vehicle utilization.Given the same total shipment volume,the improved algorithm completes transport tasks with fewer vehicles,increases the average number of loads per vehicle,and significantly improves load consolidation.It also converges faster and exhibits a smoother,less volatile post-convergence curve.Compared with the standard genetic algorithm,the improved algorithm increases carrier profit by approximately 32.6％,40.6％,48.6％,and 31.3％across four cargo sets,reduces shipper cost by about 3.2％,10.3％,11.5％,and 7.6％,and raises platform revenue by about 0.9％,0.1％,2.4％,and 0.1％,respectively.Overall,the three-stage matching model and the improved genetic algorithm better balance the interests of carriers,shippers,and online freight platforms.

Abstract:To investigate the impact of pollutants generated from the operation of airport ground support equipment(GSE)on air quality and the environment,taking an international airport as the research object,ground support equipment is classified into 17 categories according to their primary purposes,and the emission standards of ground support equipment are statistically analyzed.A calculation method for key operating parameters of ground support equipment is proposed,real-time operational data are collected,and the commonly used operating speeds,load factors,and annual pollutant emissions of ground support equipment are calculated to analyze emission characteristics.The feasibility of electrification upgrade for airport ground support equipment is explored,and a comparative analysis is conducted on the economic benefits,environmental benefits,and operational convenience of two strategies:upgrading existing baggage carts to new equipment complying with China's National Ⅵ Emission Standard versus replacing them with pure electric baggage carts.The research results indicate:1)Among the 17 types of fuel-powered ground support equipment,the top 5 ground support equipment in terms of annual pollutant emissions are baggage carts,catering trucks,aircraft tow tractors,runway maintenance vehicles,and ground support shuttle vehicles.The annual emissions of CO,HC,NOx,PM2.5,and PM10 from these 5 types of ground support equipment account for 76.3％,80.0％,63.3％,85.3％,and 85.5％of the total annual emissions,respectively.2)When the airport replaces existing baggage carts with new equipment complying with China's National Ⅵ Emission Standard,the annual emissions of CO,HC,NOx,PM2.5,and PM10 are reduced by 23.1％,15.4％,37.2％,43.2％,and 43.1％,respectively.3)The initial investment for electric baggage carts is 80 000 yuan more than that for China's National Ⅵ Emission Standard fuel baggage carts,but the annual energy cost savings and annual maintenance cost savings are 16 500 yuan and 357 yuan,respectively,with a payback period of approximately 4.75 years.Electric baggage carts have higher initial investment but lower operating costs throughout their entire lifecycle,demonstrating more significant economic benefits.Electric ground support equipment does not produce harmful substances such as NOx during operation,and the noise generated is 10-20 dB lower than fuel vehicles of the same power.Electric ground support equipment has lower manual maintenance costs and adopts continuously variable transmission structure,improving the operational reliability of ground support equipment and reducing driver labor intensity.

Abstract:To study the cyclic dynamic characteristics of red clay in Nanning area,dynamic triaxial cylindrical specimens(hereinafter referred to as specimens)are prepared for a series of dynamic triaxial tests.The effects of different consolidation confining pressures,cyclic stress ratios,and loading frequencies on the dynamic strength degradation and dynamic deformation evolution characteristics of Nanning red clay are investigated,along with an analysis of the variation patterns of dynamic elastic modulus and damping ratio.The test results indicate that:1)Under different loading conditions(consolidation confining pressure,loading frequency,cyclic stress ratio),the dynamic stress of the specimens decreases rapidly and then tends to stabilize with the increase of the number of cycles.For the same number of cycles,dynamic stress increases with the increase of consolidation confining pressure,while it decreases with the increase of loading frequency and cyclic stress ratio,indicating that consolidation confining pressure,loading frequency,and cyclic stress ratio have a significant impact on the dynamic stress of the specimens.2)Under a consolidation confining pressure of 300 kPa and a loading frequency of 1.0 Hz,the compressive strength of the specimens reaches its maximum;furthermore,after a certain number of loading cycles,the sensitivity of compressive strength to loading conditions decreases.3)Consolidation confining pressure,cyclic stress ratio,and loading frequency all influence the dynamic elastic modulus of the specimens,which is characterized by a decrease in dynamic elastic modulus and a slowing rate of decrease with the accumulation of dynamic strain;for the same dynamic strain,the dynamic elastic modulus increases with the increase of consolidation confining pressure and loading frequency,while it decreases with the increase of cyclic stress ratio;under different conditions of consolidation confining pressure,loading frequency,and cyclic stress ratio,the inverse of the dynamic elastic modulus is approximately linearly correlated with dynamic strain.4)When the increment of dynamic strain is the same,the change in damping ratio decreases with the increase of consolidation confining pressure;it remains relatively constant and then decreases with the increase of cyclic stress ratio;and it decreases with the increase of loading frequency;the damping ratio fluctuates within a certain range and increases with the increase of dynamic strain.

Abstract:To promote the high-value utilization of agricultural solid waste in road engineering,a preparation and optimization process for corn straw fiber is proposed.Under the modification parameters of fibers with a mass ratio of NaOH to water of 4％,5％,and 6％,and cooking for 0.5,1.0,and 1.5 hours,as well as soaking for 0.5,1.0,and 1.5 hours,the synergistic effects of modification parameters on the oil absorption and heat resistance of the fibers are studied based on orthogonal experiments,range analysis,and variance analysis.Dynamic shear rheology and bending beam rheology tests are used to measure the high and low-temperature rheological properties of unmodified corn straw fibers,modified corn straw fibers,lignocellulosic fibers,and fiber-free asphalt mastic,verifying the technical feasibility of replacing lignocellulosic fibers with corn straw fibers.The results show that NaOH modification significantly increases the oil absorption rate of corn straw fibers and reduces their mass loss.The degree and significance of the influence of each modification parameter on fiber oil absorption and heat resistance are arranged in descending order as follows:cooking time,mass ratio of NaOH to water,and soaking time.The optimal modification process combination for corn straw fibers is a NaOH to water mass ratio of 6％,cooking for 1.5 hours,and soaking for 1.5 hours.Under the optimal modification conditions,the oil absorption rate of modified corn straw fibers increases by 1.54％compared to lignocellulosic fibers,and the mass loss decreases by 84.88％.The complex modulus,rutting factor,and creep rate of modified corn straw fiber asphalt mastic increase by 20.80％(48 ℃),21.95％(48℃),and 5.27％(-12℃),respectively,compared to lignocellulosic fiber asphalt mastic,with both having comparable stiffness moduli.Corn straw fibers used for asphalt modification provide both high-temperature stability and low-temperature crack resistance,making them a viable substitute for lignocellulosic fibers in asphalt pavement construction.

Abstract:To study the effect of aluminum ester modified mineral powder on the water stability performance of SBS modified AC-20C,limestone mineral powder is used as raw material,and aluminum ester served as the modifier.Aluminum ester modified limestone mineral powder is prepared using a chemical method,with oil absorption value and activation degree selected as evaluation indicators.An orthogonal experiment is conducted to explore the optimal modification process.The microstructural characteristics of ordinary mineral powder and aluminum ester modified mineral powder asphalt mastic are compared using fluorescence microscopy.Residual stability and freeze-thaw splitting strength tests are performed on the aluminum ester modified AC-20C specimens.The results show that the optimal modification conditions for aluminum ester modified mineral powder are a test temperature of 80 ℃,a mass fraction of aluminum ester mineral powder of 1.0％,and a modification time of 50 minutes.The activation degree of SBS modified AC-20C with aluminum ester modified mineral powder is 27.9 times that of ordinary mineral powder AC-20C,while the oil absorption value decreases by 58.7％.In terms of water stability performance,the residual stability of SBS modified AC-20C with aluminum ester modified mineral powder increases by 4.48％compared to ordinary mineral powder AC-20C,and the freeze-thaw splitting strength increases by 6.52％.Aluminum ester modified mineral powder can effectively improve the water stability performance against stripping of SBS modified AC-20C.

Abstract:To alleviate traffic congestion caused by urban road maintenance and improve traffic efficiency during maintenance operation,two typical urban road maintenance work zones in Fuzhou(single-lane closure and double-lane closure)are selected for analysis.Using video image recognition technology,vehicle operation data in the maintenance work zones are collected,and vehicle trajectories are extracted using Tracker software.Data processing and analysis is conducted with MATLAB and SPSS to examine the spatiotemporal distribution and speed characteristics of vehicles under maintenance scenarios,as well as the impact of maintenance work zone configurations on traffic flow.The results indicate that traffic volume in maintenance work zones varies significantly between off-peak and peak hours;after entering the warning area,vehicles shift from closed lanes to open lanes,with a marked decline in traffic efficiency during peak hours;vehicle speeds gradually decrease along the direction of traffic flow within maintenance work zones,with the lowest speeds and largest time headways observed in the activity area;in mandatory lane-changing behavior,the speed of the trailing vehicle in the target lane is a key factor influencing lane-changing decisions;in the two maintenance work zones,the proportions of lane-changing vehicles with higher speeds than those of the trailing vehicle are 65%and 71%,respectively;during peak hours,lane-changing initiation points are closer to the downstream end of the warning area,and the closer the lane-changing initiation point is to the activity area,the longer the lane-changing duration is.

Abstract:To promote high-quality development of commerce logistics and regional coordination,53 cities designated as national commerce-service logistics hubs are selected as sample cities.Based on panel data from these sample cities from 2014 to 2022,an evaluation index system is constructed with five dimensions:economic development level,commerce development level,infrastructure level,logistics development level,and talent-information potential.The entropy weighted-technique for order preference by similarity to ideal solution method is used to calculate comprehensive development level scores.A coupling coordination degree model is emplayed to quantify interactions and coordination among indicators,while the Dagum Gini coefficient is applied to analyze regional disparities.Results indicate that the average comprehensive development level of 53 sample cities increases steadily from 0.099 in 2014 to 0.156 in 2022,representing a cumulative increase of 57.58%,though the overall level remains low and requires improvement;the coupling coordination degree continuously improves,transitioning from mild imbalance to marginal imbalance,yet overall coordination stays suboptimal;regional disparities primarily stem from inter-regional differences,with an average annual contribution rate of 40.18%,making inter-regional gap reduction essential for curbing the expansion of overall disparities.

Abstract:To address the challenges of high transportation costs,elevated spoilage rates,and prominent carbon emissions in cold-chain logistics,this study develops a fresh-product cold-chain vehicle routing optimization model over a time-dependent road network,aiming to minimize total cost.The model jointly considers fixed vehicle usage cost,transportation cost,refrigeration cost,spoilage cost,carbon-emission cost,and time-window penalty cost.An improved African vulture optimization algorithm(AVOA)is proposed to solve the model by introducing an initialization strategy based on time-window centers and spatial savings,an adaptive parameter-control mechanism,and a multi-level local search strategy,while incorporating the global search strategy of the aquila optimizer.Computational experiments show that,when carbon emissions are considered,the improved AVOA reduces total cost by about 25.7%compared with the original AVOA and decreases the required fleet size from 9 to 7 vehicles.Furthermore,the total cost when accounting for carbon emissions is about 1.13%lower than when carbon emissions are not considered.The improved AVOA demonstrates markedly superior route-search capability over traditional algorithms,simultaneously optimizing distribution routes while internalizing carbon-emission costs to achieve both cost reduction and low-carbon delivery.The proposed approach provides an effective solution for cold-chain logistics routing.

Abstract:To enhance the accuracy of traffic accident severity prediction,an FHSPSO-RF model is developed,where foraging habitat selection particle swarm optimization(FHSPSO)is used to optimize key hyperparameters of a random forest(RF).Using traffic accident data from Seattle,Washington,from January 2022 to February 2023,twelve features are selected.The synthetic minority oversampling technique is applied to increase the samples of severe-injury and fatal crashes and improve class balance.The FHSPSO-RF model is compared with support vector machine(SVM),K-nearest neighbors(KNN),and logistic regression(LR).Shapley additive explanations(SHAP)are used to interpret how each feature influences severity.Results indicate that after oversampling,the recall of severe-injury and fatal crashes increases significantly,and the FHSPSO-RF model achieves more balanced overall performance.The model attains higher accuracy,precision,recall,and F1 score than the three benchmarks,yielding the best severity prediction.Across all crash types,the numbers of injuries and vehicles are the most influential drivers with significant positive effects on severity.The number of pedestrians,high-impact collision types such as head-on crashes,and complex road environments such as intersections and ramps form key risk combinations for severe-injury and fatal crashes.Property-damage-only crashes are closely related to whether a parked roadside vehicle is struck.The FHSPSO-RF model demonstrates strong predictive performance and interpretability,providing support for crash risk prediction and prevention-control decision making.

Abstract:To investigate the mechanical properties of the negative bending moment zone(NBMZ)at the pier top of a simply supported to continuous girder,the deformation coordination condition is taken as the continuous rotation angle at the pier top fulcrum.The analytical expression of the restraint bending moment in the NBMZ at the pier top is derived using bilinear method(BM)and age-adjusted effective modulus(AAEM)method.Theoretical analysis are carried out.The results of the proposed method are compared with that of the field experiments and Portland Cement Association(PCA)method and Construction Technology Laboratories(CTL)method.The research results indicate that the tensioning of prestressed reinforcement has the greatest impact on the negative bending moment zone at the pier top during the process of simple supported to continuous girder;The values of the proposed method are in good agreement with the measured experimental values and PCA method and CTL method.This indicates the proposed method BM-AAEM has the high accuracy,which can preliminarily estimate whether there is a risk of cracking in the NBMZ at the top of the pier.

Abstract:To systematically evaluate the ability of urban rail transit networks to withstand uncertain disruptions,this study takes the Shijiazhuang urban rail transit(planned)network as the research object.Based on complex network theory,an undirected and unweighted topology is constructed using the Space-L method.Network characteristics are identified by computing topological parameters such as degree distribution,average path length,and clustering coefficient.Six attack strategies covering node and edge failures are designed,and network resilience under random and targeted attacks is assessed using network efficiency and the proportion of the largest connected component.Critical nodes and edges are identified through sequential single-node and single-edge failure experiments.Results show that,compared with a corresponding random network,the Shijiazhuang(planned)network yields a small-world index of s=1.110 3>1.000 0,and its degree distribution approximately follows a Poisson distribution,indicating small-world properties.The network is sensitive to targeted attacks based on node degree and node betweenness,while it exhibits stronger robustness to attacks based on edge betweenness.The impacts of different node or edge failures on network efficiency vary markedly,and static topological indicators(degree,betweenness)are not in a simple positive correspondence with the actual performance degradation caused by their failures.Resilience should be enhanced by strengthening the protection of critical stations and track sections,optimizing the network topology,and establishing a multimodal emergency intermodal system.