In order to explore the influence mechanism of arch bridge deformation on the running stability of the train under crosswind, the horizontal and vertical displacement of the mid-span was obtained through the wind, vehicle, and bridge coupling system, and the running stability of the train under different wind speeds and train speeds was analyzed. The contribution of bridge deformation to horizontal and vertical acceleration of the train in the wind, vehicle, and bridge system was quantified. Combined with the sensitive wavelength of the acceleration response of the train and the time-frequency characteristic of bridge deformation, the influence mechanism of bridge deformation on running stability was analyzed. The results show that the vertical displacement difference of the bridge is smaller than the horizontal displacement difference, and the main displacement is caused by the vehicle-induced bridge deformation. The maximum value reaches −9.2 mm. Under the action of train and wind load, the horizontal and vertical displacement of the bridge is more significant, but its influence on the stability of the train is mainly reflected in the position of the junction pier, which is about four times the response of other positions. Except for the junction pier area, the running stability of the train on the bridge is mainly determined by the wind-induced train vibration and track irregularity. The spectral density distribution of horizontal and vertical acceleration power of the train is closely related to the wavelength of track irregularity, and the corresponding sensitive wavelength range is less than 120 m. The horizontal and vertical acceleration of the train is mainly affected by the bridge deformation caused by the vehicle load, while the bridge deformation caused by wind load is mainly distributed in the main span, and the wavelength is larger than 120 m. Therefore, it does not exert a significant impact on the acceleration of the train.

The stay cable is one of the main load-bearing elements of cable-stayed bridges, and the disease of its outer sheath is easy to penetrate inside the cable and affect the health of the steel wire. Therefore, it is significant to use the video image method to intelligently identify the apparent disease of the cable. Based on image recognition, the methods of apparent disease recognition for stay cable were systematically reviewed from two aspects: traditional image detection and deep learning. The basic principles and application effects of each method were introduced, and the current detection examples were analyzed. Some cutting-edge deep learning methods were introduced to provide a reference for the apparent detection of cables. The main features of various methods were summarized, and the problems existing in the current detection were discussed and prospected. The deep learning model-based image recognition method had better recognition accuracy and algorithm robustness, stronger learning ability and adaptability, and optimal comprehensive image defect recognition effect, but there were still difficulties such as the difficult balance between detection accuracy and speed, large image data demand, and high labeling cost. To this end, detection methods could be improved by improving image quality, constructing more semi-supervised and unsupervised deep learning models, and enhancing the learning ability of detection models.

To reveal the variation law of dynamic response of maglev guideways, maglev trains were simplified as moving uniform loads, and analytical methods were employed to obtain the analytical solutions for dynamic response of simply supported guideways. The variation laws of the maximum response of guideways with train speed and guideway span were discussed, and the extremum conditions of response of maglev guideways were derived, which were verified by finite element and train-bridge coupling vibration methods. The results show that under the condition of a large train-guideway span ratio, the maximum response of midspan increases with fluctuations as the train speed increases and has extremums. Guideway response also has similar change laws with the variations of guideway span, mass, and other parameters. When the product of span and speed is a specific constant, or the product of the first-order vertical frequency and span of guideway is a specific time the train speed, the guideway produces vibration isolation.

In order to study the shear behavior of studs embedded in engineered cementitious composites (ECC), model tests and the numerical analysis of finite elements were carried out. The failure mode of studs embedded in ECC was determined based on push-out model tests. Then, parametric numerical analysis of finite element was performed to elucidate the effects of stud diameter, height/diameter ratio of stud, tensile strength of stud, and compressive strength of ECC on the shear behavior and failure mode of connectors. Finally, a method for calculating the shear capacity of studs embedded in ECC was established according to the above research. The results show that the shear strength of studs embedded in ECC is closely related to the failure mode of the push-out model. When the push-out model fails due to ECC crushing, the shear strength of the connector depends on the compressive properties of ECC. When the push-out model fails due to stud fracture, the shear strength of the connector depends on the tensile strength of the stud and compressive properties of ECC; increasing the compressive strength of ECC and reducing the height/diameter ratio of the stud both can improve the shear stiffness of the connector, but the tensile strength of the stud has a slight effect on the shear stiffness of the connector. When the height/diameter ratio of the stud is lower than 4.60, the shear strength of the stud reduces with the decreasing height/diameter ratio of the stud. Studs with a height/diameter ratio of greater than 4.60 are recommended to serve as a shear connector applied in steel-ECC bridge decks.

This paper aims to study the effect of spanwise variation of vibration amplitude and spanwise correlation of the nonlinear aerodynamic forces on the vortex-induced vibration (VIV) response of bridges. Firstly, a nonlinear aerodynamic force model of the bridge represented by polynomial functions of vibration amplitude was introduced. Secondly, on the basis of the two-dimensional VIV (2D VIV) analysis method, an approach for predicting the three-dimensional VIV (3D VIV) amplitude response with consideration of both spanwise variation of vibration amplitude and spanwise correlation of aerodynamic forces was proposed through theoretical analysis. Finally, by taking a 1 700 m long-span suspension bridge as an example, the nonlinear aerodynamic force parameters of vertical VIV of the bridge girder at different angles of wind attack were extracted through a wind tunnel test. Then, the VIV amplitude response of the suspension bridge under a first-order positive symmetrical vertical mode at different angles of wind attack was analyzed. The results prove that when the aerodynamic forces are assumed to be fully correlated along the span, the 3D analysis under different wind speeds leads to a significantly higher VIV amplitude response (about 19%) as compared with the 2D analysis method due to the effect of spanwise variation of vibration amplitude of the aerodynamic forces. However, when the aerodynamic forces are assumed to be partially correlated along the span, the VIV amplitude response by 3D analysis is reduced significantly, and the reduction range is about 16%–30% under most wind speeds and about 70% under certain wind speeds. It is proved that it is important to accurately predict the VIV amplitude response of long-span bridges by considering the spanwise variation of vibration amplitude and spanwise partial correlation of aerodynamic forces. The approach proposed in this paper is also applicable to the analysis of torsional VIV or VIV at higher-order modes.

To investigate the effect of freeze-thaw cycles and coupling of freeze-thaw cycles and bending loads on the flexural performance of polypropylene fiber cement-based composite (PP-ECC) beams, seven experimental working conditions were set up. In addition, the three-point loading method was adopted to explore the flexural performance of PP-ECC beams. The differences in load-span deflection curves, flexural bearing capacity, and crack development patterns of PP-ECC beams under coupling of freeze-thaw cycles and bending loads were analyzed. Based on the calculation assumptions and the calculation model of the flexural bearing capacity of PP-ECC beams under normal environments, combined with the freeze-thaw deterioration mechanism of PP-ECC materials, the calculation model of flexural bearing capacity of PP-ECC beams under freeze-thaw environments was deduced. Furthermore, the load-bearing damage coefficient γ was introduced on this basis. The calculation model of the flexural bearing capacity of PP-ECC beams under the coupling of freeze-thaw cycles and bending loads was established. The research results show that the ultimate flexural bearing capacity of PP-ECC beams with different load-bearing ratios decreases to varying degrees under freeze-thaw cycles. After 500 freeze-thaw cycles, the ultimate flexural bearing capacity of PP-ECC beams with load-bearing ratios of 0, 0.25, and 0.5 decreases by 28.70%, 27.09%, and 35.69%, respectively. After cracking under tension, the PE-ECC material can still work with the rebar under tension and participate in the stress of the whole section. When the PP-ECC beam reaches the limit state, the zone under tension develops steadily with multiple cracks. With the aggravation of freeze-thaw damage, the width of the largest crack in the beam body increases, and the number of cracks decreases. The PP-ECC beam subjected to freeze-thaw cycles and coupling of freeze-thaw cycles and bending loads still satisfies the plane section assumption. The coincidence degree of the flexural bearing capacity calculation models of PP-ECC beams under freeze-thaw cycles and coupling of freeze-thaw cycles and bending loads established based on the plane section assumption is 0.88–1.06 and 0.96–1.10, respectively.

To investigate the seismic performance of concrete composite columns of ultra-high performance concrete (UHPC) precast pipe under low-cycle repeated loads, three concrete composite columns of UHPC precast pipes and one reinforced concrete (RC) column were subjected to quasi-static tests, so as to analyze the seismic performance of each composite column specimen in terms of damage mode, displacement ductility, energy dissipation capacity, and stiffness degradation under different UHPC strengths and core concrete with or without reinforcement. The analysis results show that the hysteresis curves of the concrete composite column specimens of UHPC precast pipe are fuller, and their damage patterns are basically the same, which are both integral compression-bending damage. Compared with those of the conventional RC columns, the stiffness, yield load, and ductility of the concrete composite column of UHPC precast pipe are improved. With the increase in UHPC strength, the hysteresis curves of the composite column specimens are fuller, and the energy dissipation capacity is enhanced. The residual displacement is small, and the horizontal peak load and displacement ductility coefficient increase by 20.6% and 6.4%, which shows good overall seismic performance. The finite element analysis model of the composite column is established by the ABAQUS program, and the calculation results are in good agreement with the test results. Different axial compression ratios, slenderness ratios, and UHPC strengths are important parameters affecting the seismic performance of concrete composite columns of UHPC precast pipes, which can provide a reference for similar engineering designs.

In order to master the constraint effect of new high-strength steel wire cloth reinforced ultra-high performance concrete (UHPC), a study was conducted on the influence of the surface density and number of layers of high-strength steel wire cloth on the axial compression performance of confined concrete columns. Firstly, the constraint effect of high-strength steel wire cloth reinforced UHPC was evaluated using Poisson’s ratio, ductility index, and toughness index. Secondly, a lateral constraining force model of the composite constraining layer was established considering the constraining force provided by high-strength steel wire cloth and UHPC. Finally, a constitutive model of axial compression of confined concrete was established based on the Ottosen failure criterion and an effective constraint index. The results show that the confined column exhibits obvious ductile failure under compression, and the high-strength steel wire cloth reinforced UHPC confinement system can effectively suppress crack development and slow down the stiffness degradation of the specimen in the later stage of loading. Compared with the unconfined column, confined columns have maximum increases of 147.0%, 104.0%, and 58.0% in ultimate bearing capacity, peak compressive strain, and peak stress, respectively. When the number of layers of high-strength steel wire cloth increases from 1 to 2, and the surface density increases to 3.3 times, the ultimate bearing capacity, peak compressive strain, and peak stress of the confined column increase by 8.4%, 29.3%, and 15.8%, respectively, while the ductility index and toughness index increase by 50.3% and 44.2%, respectively. The model established in this paper highly agrees with the experimental results compared with the classical constitutive model of axial compression of confined concrete.

To study the bearing capacity of energy piles in sand affected by thermal－cool cycles, a centrifuge model test on slender energy piles buried in Fengpu sand with different compactions was carried out. The change rules of the axial force, side friction, and individual bearing capacity of energy piles were obtained and compared under 20 thermal－cool cycles in the test. The test results show that the axial force of the energy pile decays gradually and tends to be stable with increasing thermal－cool cycles. The maximum axial force attenuation value of the energy pile buried in the sand with medium compaction is much larger than that buried in the dense sand. During thermal－cool cycles, for energy piles buried in the sand with medium compaction, a neutral point is located at the bottom half of the pile. Positive additional side friction is generated above the neutral point during cool cycles, and negative additional side friction is generated underneath the neutral point. Oppositely, during thermal cycles, negative additional side friction appears above the neutral point, and positive additional side friction is underneath the neutral point. The dense sand has an obvious constraint effect on the lower part of energy piles. Positive additional side friction is distributed along the pile during cool cycles because the pile moves downward relative to the surrounding soil. During thermal cycles, the additional side friction is negative. The bearing capacity of the energy piles will be reduced because of the long-term temperature cycles. The bearing capacity of the energy piles buried in the dense sand and sand with medium compaction is reduced by 7.3% and 15.6%, compared with the prototype pile. The bearing capacity of the prototype pile and energy piles buried in the dense sand is 11% larger than that of the prototype pile buried in the sand with medium compaction. Therefore, reasonable measures should be taken to meet the bearing requirements of energy piles when buried in sandy layers with different compactions in actual engineering.

To study the buckling performance and bearing capacity design method of the cold-formed thin-walled steel (CFTWS) with unequal-leg lipped angles under axial compression, the tests were conducted, and a finite element program was used to analyze the buckling performance and ultimate bearing capacity. Based on the direct strength method, the bearing capacity design method was presented. Firstly, the 32 CFTWS with unequal-leg lipped angles with different sections, slenderness ratios, and width-to-thickness ratios were tested under axial compression. Then, ABAQUS finite element software was used to perform parametric analysis on the buckling performance and bearing capacity of CFTWS with unequal-leg lipped angles with different width-to-thickness ratios, width ratios of legs, and slenderness ratios. Finally, the modified direct strength method for calculating the bearing capacity of CFTWS with unequal-leg lipped angles under axial compression was proposed based on the results of the test and finite element analysis. The results show that the specimens with a small width-to-thickness ratio are prone to flexural-torsional buckling, while the specimens with a large width-to-thickness ratio are prone to the local buckling or buckling related to flexural-torsional buckling and local buckling. The ultimate bearing capacity of the specimens decreases with the increase in the slenderness ratio, and the increase amplitude of the bearing capacity slows down with the increase in the width-to-thickness ratio. The reliability analysis shows that the reliability indexes of the bearing capacity of the CFTWS with unequal-leg lipped angles under axial compression calculated using the modified direct strength method are greater than 3.2, indicating that the proposed method is accurate and reliable.

To investigate the effect of synergistic longitudinal ventilation and air curtain on the control of tunnel fire smoke in urban bifurcated tunnels, the 1∶10 small-sized bifurcated tunnel fire experiments were conducted, and the along-travel and maximum temperatures of bifurcated tunnels under the synergistic effect of longitudinal ventilation and air curtains were analyzed by taking into account the variables of longitudinal ventilation, jet velocity, angle, and thickness of air curtain. Firstly, the smoke and heat insulation effect of the air curtain was analyzed through 57 sets of small-sized tunnel fire experiments. Then, based on the dimensionless empirical correlation formula for the maximum temperature rise of the ceiling in a tunnel fire, a model of the maximum temperature rise under the synergistic effect of air curtain and longitudinal ventilation was constructed at a fixed heat release rate of 47.9 kW. Finally, the experimental values of the maximum temperature rise under different working conditions were compared with the predicted values of the theoretical models of the maximum temperature rise. The results show that an air curtain can effectively help longitudinal ventilation reduce the temperature in the main tunnel by up to 420 ℃ while effectively preventing smoke from entering the bifurcated tunnels. When the jet velocity of the air curtain is small, the increase in longitudinal wind speed can effectively prevent the accumulation of smoke in the bifurcation and improve the insulation efficiency of the air curtain on the smoke. In addition, the temperature of the smoke at the tunnel bifurcation point can be reduced by up to 170 ℃. The constructed theoretical model of the maximum temperature rise is compared with the experimental results, and the error between them is less than 10%.

Establishing a reasonable and accurate theoretical analysis model for pipe sheds and solving it are of great significance to promoting the development of pipe shed pre-support technology. By analyzing the construction process of tunnel excavation and support and the reduction of the restraining reaction force of the pipe shed due to the disturbance of the tunnel face in the unexcavated section, a load structure model of the pipe shed based on the Euler-Bernoulli beam theory was established. The Pasternak elastic foundation model was introduced to determine the initial support and the restraining reaction force of the rock mass in front of the tunnel face on the pipe shed, and the analytical expressions of the stress and deformation of the pipe shed during each cycle of tunnel excavation and support were derived. In addition, the superposition method was used to solve the stress and deformation distribution of the pipe shed when the tunnel face was tunneled to any position. Through case comparison, the rationality and effectiveness of the model were verified. The research results show that smaller circumferential spacing and larger diameter of the pipe shed steel pipes are helpful in improving the pre-reinforcement capacity of the pipe shed, and the reasonable lap length of the pipe shed is 1.8 m.

In order to deeply study the protective effect of geogrid-reinforced buried pipelines under vertical load, indoor model tests were carried out, and a discrete element simulation analysis model was established. The mechanical response and deformation behavior of geogrid-reinforced buried pipelines and surrounding soil systems under vertical load were explored from the mesoscopic level, and the development and evolution laws of the load-settlement curve of loading plate, contact force between particles inside the model, particle displacement, and vertical radial deformation of pipelines were revealed under different buried depths of pipelines and reinforcements. The results show that when the buried depth of the pipeline H is shallow (H = 1.5D, D is the outer diameter of the pipeline model), the ultimate bearing capacity is smaller than that of the pipeline with a large buried depth. Although the settlement of the loading plate is smaller under the same load, the vertical radial deformation of the pipeline is large. After the geogrid above the pipeline is reinforced, the ultimate bearing capacity of the model system is significantly increased, and the vertical radial deformation of the pipeline is reduced. A shallower buried depth of the geogrid indicates a more obvious reinforcement effect. When the buried depth of the geogrid u is reduced from 0.75B to 0.25B, the ultimate bearing capacity is increased by about 57.2%, and the radial deformation of the pipeline is reduced by about 27.9%. In this study, the interaction mechanism among pipelines, soil, and geogrid is revealed from the mesoscopic level, and the mechanical and deformation behavior of geogrid-reinforced protected buried pipelines were visualized.

Loose particle accumulations are widely present in nature and industrial production activities. In order to study their mechanical properties and instability processes, acoustic emission (AE) technology was used to explore the evolution law of acoustic characteristics of loose particles in a shear process. Firstly, the AE characteristic parameters of loose particles at different shear rates were analyzed. Then, the AE evolution stages were divided based on the mechanical characteristics of the loading process. Finally, the AE evolution law of loose particles under shear failure was further verified with spectral changes and the proportion of wavelet packet energy. The results show that the energy and ringing count increase gradually with the shear process. The faster the shear rate, the larger the increases of energy and ringing count. The number ratio of small events to large events (b value) decreases gradually during the shear process, and the larger the shear rate, the smaller the b value. The shear strength of particles at different rates is about 140 kPa, and the peak shear force is about 400 N. The changes of ringing count, AE energy, and b value during shear motion are closely related to shear failure stage. The spectral barycenter gradually decreases in the shear process from about 350 kHz to 250 kHz. Meanwhile, the energy proportion of the low frequency band increases, and the energy proportion of the high frequency band decreases accordingly, which results in a spectral barycenter constantly moving down.

The traditional prediction model for the civil engineering cost of urban rail transit lacks decision-making credibility. To address this issue, First, critical factors affecting the civil engineering cost of urban rail transit were retrieved utilizing the feature selection and knowledge judgment methods, and an engineering case database was created. Then, similar cases were screened using the particle swarm optimization (PSO) clustering algorithm, and a nonlinear prediction model of civil engineering cost was established using the extreme learning machine (ELM) based on gray wolf optimizer (GWO), followed by a dual environment comparison experiment. Finally, Sobol’s global sensitivity analysis and curve fitting analysis were conducted to invert the model and validate its superiority by using the Chengdu Rail Transit Line 10 Phase 1 Project as an example. The results show that the prediction model’s mean absolute error and root mean square error are 0.113 9 and 0.127 4, respectively, and the mean absolute percentage error is 4.14%. The prediction effect of the nonlinear cost prediction model is better than that of the linear model, and the better prediction effect is obtained by simultaneously using the factor optimization and case clustering methods. The global sensitivity study reveals that the total sensitivity of the subterranean line length and the number of underground stations is much larger than the other factors, making them the major factors to be adjusted for the scheme optimization. The “black box” effect of intelligent predictive modeling mechanism based on machine learning is better understood by 33.70%–64.52% when curve fitting analysis is used.

New continuous cable traction power supply system (CCTPSS) can achieve long-distance transmission and reduce the number of electric phases. However, the two-stage power supply mode leads to the complex structure of the system. In order to reveal the short-circuit characteristics of CCTPSS, the two-port network parameters of traction cable and catenary-rail of unit length were established. Each sub-network was cascaded and equated with a two-port network, which was then transformed into a Ⅱ-type circuit for modeling the distribution parameters of the traction cable and catenary-rail of any length. The locomotive voltage drops after short circuit of catenary. Therefore, considering the coupling relationship between the train and the network, the short-circuit current and voltage were solved by iterative calculation. The accuracy of the calculation method was validated by simulation. Finally, the electrical characteristics of different short-circuit types were analyzed, with emphasis placed on the influence of distributed capacitance on short-circuit current and voltage. The results show that the distributed capacitance can increase the short-circuit current and, under different short-circuit conditions, the output voltage of traction transformer. The short-circuit current of catenary is jointly provided by traction transformers on both sides, and the farther away from the short-circuit point is, the less current is provided. The cable phase-to-phase short circuit has the greatest impact on the operation of the non-fault-circuit locomotive.

In response to the problem that direct current (DC) bias current of neutral grounded transformer is affected by dynamic stray current leakage and depot grounding of rail transit, a metro-earth-grid coupling model of stray current distribution and diffusion under multi-train operation was proposed, and the complex image method was used to calculate the earth potential. The self and mutual resistance coefficients of grounding grids were defined, and the coupling relationship between DC bias current and earth potential was proposed. The field-circuit coupling model of earth potential and DC bias current was built according to the topology of stray current intrusion path. A scaled-down simulation test of stray current intrusion into the grid for rail transit was designed, and tests and model calculation were conducted for verification. The results show that the maximum error between the experimental data and the model calculation data is 8.41%. The rail-to-earth transition resistance increases from 3.00 Ω·km to 15.00 Ω·km, and the absolute average of DC bias current decreases by 82.4%. Using a blocking connection device between the car depot and the main line can reduce DC bias current by 23.45% compared with using a unidirectional conduction device.

With the explosive development of electric vehicles (EV), the contradiction between the impact of charging load and grid support capacity is highlighted. In response to this problem, an EV charging and discharging (vehicle to grid, V2G) optimization strategy was proposed from the perspective of the game between supply and demand. Firstly, a power price sharing mechanism was constructed to make EV charging and discharging mutually appropriate with base load by combining the characteristics of EV charging and discharging behaviors. Then, for the leader-follower game relationship between the aggregator’s pricing of electricity and the EV users’ charging and discharging behavior selection process, an optimization model was established, whose optimization objectives are maximizing the revenue of the aggregator on the leader level and minimizing the cost of electricity for EV users on the follower level. Finally, the seeker optimization algorithm was used to solve the optimization objectives of both sides separately, and the game cycle was carried out until the equilibrium, so that the optimal electricity pricing strategy and EV charging/discharging strategy were obtained. The simulation results show that the proposed charging and discharging strategy can realize the peak-cutting and valley-filling of the base load curve by the EV charging and discharging load. The variance of the base load curve is reduced by 56.6%, and the difference between peak and valley is decreased by 28.0%. Meanwhile, the charging and discharging cost of EV users is lowered by 40.4%, and the revenue of the aggregator is increased by 40.1%.

In order to design an efficient and robust evolution algorithm, the fixed point iteration idea in solving equations was first introduced into the optimization field. The optimization process of an evolution algorithm was regarded as the gradual display process of the fixed point of an equation in an iterative framework. On this basis, a novel evolution algorithm based on a mathematical model was developed, named fixed point evolution algorithm (FPEA). The reproduction operator of FPEA is a quadratic polynomial which is derived from a fixed point iteration model with the Aitken method. The overall framework of FPEA inherits the population-based iterative model of traditional evolution algorithms such as differential evolution algorithm. The experimental results show that the average ranking of the optimal value of FPEA ranks first among all the compared algorithms on benchmark functions CEC2014 and CEC2019. The proposed algorithm can achieve the highest solution accuracy with a low computational overhead on four engineering constraint design problems among the compared algorithms including CSA and GPE.

First-order logic-based automatic theorem provers (ATPs) are important for the research on knowledge representation and automatic reasoning, and heuristic strategies are a critical research topic to enhance the performance of ATPs. Mainstream heuristic strategies select clauses by describing clause properties and then determining the priority of the properties. However, the priority of properties is subject to human factors, and it takes a long time to evaluate clauses. A new multi-criteria decision making (MCDM) clause evaluation method was proposed based on the standard contradiction separation (S-CS) rule. Firstly, the entropy weight method was used to objectively assign weights to clause properties. Secondly, preference ranking organization method for enrichment evaluations (PROMETHEE Ⅱ) was combined to evaluate the clauses and obtain the complete order of the clauses. Finally, the proposed MCDM method was applied to ATPs CSE 1.5 (contradiction separation extension 1.5), Vampire 4.7, and Eprover (E 2.6) to form new ATPs MCDM_CSE, MCDM_V, and MCDM_E. The theorems in first-order form (FOF) from the international theorem provers problem library Thousands of Problems for Theorem Provers (TPTP) were tested on MCDM_CSE, and the Conference on Automated Deduction (CADE) 2022 competition (FOF division) was tested on MCDM_V and MCDM_E. The experiments show that MCDM_CSE proves 151 more theorems (from TPTP) than CSE 1.5 and proves 5 theorems unproved by Vampire 4.7, 41 theorems unproved by E 2.6, and 293 theorems unproved by Prover9. In a shorter average time, MCDM_V proves 6 more theorems (from CADE 2022) than Vampire 4.7, and MCDM_E proves 8 more theorems than E 2.6.

In digital twin technology, the operation of complex models and production logic consumes a large number of resources. Meanwhile, differences in hardware capabilities and user requirements make it difficult to ensure simulation accuracy and real-time performance, reducing system availability. To address this issue, a real-time synchronous computing framework for digital twin manufacturing equipment that collaboratively processed visualization and logic computation was proposed. Firstly, a digital model of the equipment was constructed based on multidimensional workshop information. According to hardware capabilities and users’ personalized computational needs, a configurable and adaptive system environment mapping method was introduced to adjust simulation fidelity, ensuring the real-time and correct operation of the twin equipment. The process was illustrated by using lighting environment mapping as an example. Secondly, a simulation-based motion logic solving algorithm for a six-degree-of-freedom (6-DOF) manipulator was presented, which used the rendering frame time as the simulation clock advancement step to ensure accurate model motion and synchronization between visualization and computation. The algorithm was generalized for application to other multi-body equipment. Finally, a Web-based digital twin workshop modeling and simulation cloud platform was designed and developed. A 6-DOF manipulator and a specific bogie frame processing workshop were used as application cases, and the proposed method was validated. The results show that with the adaptive reduction of mapping fidelity, simulation response speed is increased by 45%, while GPU and CPU resource utilization is effectively reduced. It proves that the method can achieve reasonable resource allocation and efficient system computation while reducing error accumulation, making it a highly available real-time collaborative computing method.

As typical rail damage of the railway, rail corrugation is often accompanied by the fastener clip fracture, which seriously affects the operation safety of the train. Moreover, the small-radius section of the Cologne-egg fastener experiences frequent rail corrugation. To explre the fracture mechanism of Cologne-egg fastener clips, firstly, the finite element model of the wheel set-rail-fastener system, including the complete Cologne-egg fastener model, was established baesd on the field investigation. Then, the resonant response of the Cologne-egg fastener clip was explored, considering the frictional coupling vibration of the wheel-rail system. Finally, the fatigue life of the Cologne-egg fastener clip was compared in the cases of with and without rail corrugation sections, and the fatigue damage of different clips was quantified. The results show that the dominant frequency of the frictional coupling vibration of the wheel-rail system is consistent with the first-mode constraint mode of the Cologne-egg fastener clip in the frequent rail corrugation sections, which indicates that the clip resonance induced by the frictional coupling vibration of the wheel-rail system is the main reason for the Cologne-egg fastener fracture. The frictional coupling vibration of the wheel-rail system is aggravated by the rail corrugation, which makes the clip life of the Cologne-egg fastener in the rail corrugation section decrease by 99.04% compared with that in the absence of rail corrugation section. The clip life is thus only 3.11% of the design clip life. Besides, the Cologne-egg fastener clip on the low gauge side is more prone to fatigue failure in the small-radius curved section, and the failure position is located on the inner side of the rear arch end of the clip.

In order to analyze the feasibility of a dual-source-powered electric multiple unit (EMU) with enhanced operational efficiency on the Qinghai–Xizang Line (Golmud–Lhasa section), the dynamics model of EMU was established and verified. A dynamic method was adopted to study the relationship among the traction adhesion coefficients, traction force, creepage, and speed for the dual-source-powered EMU and the HXN₃ internal combustion locomotive operating on the straight sections, curved sections, and ramps of the Qinghai–Xizang Line. The adhesion characteristics of dual-source-powered EMU under traction conditions were validated by comparing the dynamic responses of the two locomotives. The analysis finds that: 1) The traction adhesion coefficients of the locomotives are proportional to their traction force. Moreover, within the speed range of 40–120 km/h, the adhesion coefficient of the dual-source-powered EMU decreases from 0.19 to 0.09, while the adhesion affluence increases from 59.0% to 85.7%. 2) The adhesion affluence of the dual-source-powered EMU is superior to that of the HXN₃ locomotive in both straight sections and ramps, thereby enhancing its ability to cope with low wheel-rail adhesion conditions in harsh external environments and exhibiting better adaptability in plateau environments. 3) In the curved section, by ignoring the structure-induced adhesion reduction difference, the adhesion reduction amplitudes of the dual-source-powered EMU and HXN₃ locomotive are 6.3% and 6.8%, respectively, at R300 m curve. At the R800 m curve, the HXN₃ locomotive demonstrates an adhesion reduction amplitude of 3.0%, while the adhesion reduction amplitude of the dual-source-powered EMU is below the threshold value, ensuring sufficient adhesion.

The cell size in the classical cellular automaton-based traffic flow model makes it difficult to express the position relationship of vehicles accurately. Therefore, a scheme to improve the symmetric two-lane cellular automaton (STCA) model by refining the cell size was presented. Firstly, the position, speed, acceleration, and interaction of vehicles in the urban road two-lane environment were analyzed, and the numerical model of these characteristics was built based on the cellular automaton. Especially, the road size and the cellular representation form in the model were improved to solve the problem that the existing traffic flow model based on cellular automaton does not conform to the vehicle driving phenomenon on the actual road. Secondly, according to the real vehicle infrastructure environment, road congestion, lane changing, and other behaviors in the STCA model were redefined, and the lane rules were combined with the refined lane model. A new traffic flow model, namely STCA-CH, was established. Finally, the model was compared with STCA, STCA-I, STCA-S, and STCA-M models, and the validity of the STCA-CH model was verified by analyzing the average speed, average flow, lane changing frequency, and space-time diagram under different vehicle densities. The results show that the lane changing frequency of the STCA-CH model is about 21.14% higher than that of the STCA-M model, and the maximum average flow is about 25.76%, 11.30%, and 3.75% higher than that of the STCA-I, STCA-S, and STCA-M models respectively.

Accurate identification of key nodes is of great significance for enhancing network resilience and improving operational capabilities. In order to improve the identification accuracy of key nodes in the en-route network, a comprehensive evaluation method based on the technique for order preference by similarity to an ideal solution (TOPSIS)-grey correlation analysis method and a node classification method for the en-route network were proposed. Firstly, an evaluation index system of key nodes in the en-route network was constructed from three perspectives: complex network characteristics, traffic volume, and vulnerability. Then, the relative entropy was introduced to improve the TOPSIS method, and the importance of en-route waypoints was comprehensively evaluated by combining this method with the grey correlation analysis method. The K-means clustering method was used to effectively divide the levels of en-route waypoints. Finally, key node identification was carried out based on the actual operation data of civil air traffic management. It finds that the results obtained by the constructed evaluation index system of key nodes in the en-route network are more comprehensive than the evaluation results of a single index. The improved TOPSIS-grey correlation analysis is more accurate than the traditional TOPSIS method. The proposed identification method finds that there are 29 key nodes in the typical busy en-route network in Eastern China, which play a key role in the network structure and traffic volume.

In order to accurately grasp the main parameters and diffusion and propagation laws inherent in urban traffic congestion sources and realize scientific control of traffic congestion sources, the Gaussian plume model for air pollutant dispersion was introduced and improved. The urban traffic congestion sources were divided into continuous traffic flow and a series of intermittent traffic flow, so as to realize the structural analysis of the Gaussian plume model. Then, three test functions, namely Griewank, Schaffer, and Rastrigin were used to test the “single point source” parameter inversion algorithm, and the seeker optimization algorithm was selected. Finally, the performance of the five typical objective functions with different numbers of parameters (one, two, and three) was evaluated in three dimensions based on the observed traffic congestion source data. The results show that in the one-parameter case, the stability of the objective function based on the sum of squared deviations of traffic density per unit area is better, and the confidence interval of the absolute value of the relative deviation of the inverse source strength is 38.38% ± 9.94%; the number of experiments less than 50.00% accounts for 84.52% of all experiments, and the stability of each objective function is better. In the two-parameter case of source strength inversion, the accuracy of the objective function based on the root-mean-square error of traffic density per unit area in the form of logarithmic transformation is the highest, and the confidence interval of the absolute value of the relative deviation of source strength inversion is 51.42% ± 9.84%; the number of experiments less than 50.00% accounts for 92.16% of all experiments. In terms of inversion location, the accuracy of the objective function based on the sum of squared deviations of traffic density per unit area is the best (absolute value of position deviation inversion is 37.22 m ± 10.64 m), and the stability of the objective function based on correlation coefficient is the strongest (coefficient of variation is 0.022). In the three-parameter case, the accuracy inversion results are more consistent with those in the two-parameter case, and the source strength stability of each objective function is poor except for the objective function in the form of logarithmic transformation, but the position stability is better.