The dynamic recrystallization behavior of high strength steel during hot deformation was investigated. The hot compression test was conducted in the temperature range of 950-1150 °C under strain rates of 0.1, 1 and 5 s^-1. It is observed that dynamic recrystallization (DRX) is the main flow softening mechanism and the flow stress increases with decreasing temperature and increasing strain rate. The relationship between material constants (Q, n, α and lnA) and strain is identified by the sixth order polynomial fit. The constitutive model is developed to predict the flow stress of the material incorporating the strain softening effect and verified. Moreover, the critical characteristics of DRX are extracted from the stress-strain curves under different deformation conditions by linear regression. The dynamic recrystallization volume fraction decreases with increasing strain rate at a constant temperature or decreasing deformation temperature under a constant strain rate. The kinetics of DRX increases with increasing deformation temperature or strain rate.

The effect of H₂ gas content on the reduction of Panzhihua titanomagnetite concentrate pellets by carbon monoxide was investigated by isothermal reduction experiment using CO-N₂-H₂ gas mixtures in a vertical electric resistance furnace. The morphology and phase transformation of reduced samples obtained were detected by scanning electron microscopy, energy disperse spectroscopy analysis and X-ray diffractometry respectively. The results show that increasing H₂ content will enhance the initial stage of reduction rate apparently. There are two reasons responsible for this effect, one is that H₂ accelerates the chemical reaction, and the other is that the addition of H₂ gas can improve the porosity of pellet intensively. It is noteworthy that this effect is more obvious when the reduction temperature reaches 1473 K with sticking phenomenon happening. There are no crystalline phases which can be found such as ulvospinle, ilmenite, ferrous-pseudobrookite and any titanium oxide except titanomagnetite (TTM). The reduction progress is suggested as follows: 1) Fe₂O₃→Fe₃O₄→FeO→Fe; 2) Fe₂TiO₅→Fe₂TiO₄+Fe₃O₄→TTM. Element Al migrates and gets enriched in high titanium content iron ores, and eventually Al to Ti molar ratio is 1:3. Al is likely to dissolve in titanium iron oxides to form a kind of composite iron compound, which results in the restrain of reduction.

Anion receptors including pyrimidine subunit were designed and synthesized and their binding abilities with various anions were investigated by fluorescence and ¹H NMR titration experiments. DFT calculations provided some information for anion recognition. It is confirmed that both of two new pyrimidine anion receptors have the selectivity for Cl^-.

To solve the problem of slow leaching speed of copper, surfactant was added into lixivium as leaching agent in the experiment. Based on physical chemistry and seepage flow mechanics, the leaching mechanics of surfactant was analyzed. The solution surface tension and surfactant adsorbing on the surface of ore have a significant impact on the surface wetting effect. With leaching rate for response, the study screened out three main factors by Plackett-Burman design method: the sulfuric acid concentration, surfactant concentration and temperature. Among these three factors, the surfactant concentration is the most important contributor to leaching rate. After obtaining the experiment center by the steepest ascent experiment, a continuous variable surface model was built by response surface methodology. By solving quadratic polynomial equation, optimal conditions for leaching were finally obtained as follows: the sulfuric acid concentration was 60 g/L, the surfactant concentration was 0.00914 mol/L, and the temperature was 45 °C. The leaching rate was 66.81% in the optimized leaching conditions, which was close to the predicted value, showing that regression result was good.

Multivariate statistical techniques, such as cluster analysis (CA), discriminant analysis (DA), principal component analysis (PCA) and factor analysis (FA), were applied to evaluate and interpret the surface water quality data sets of the Second Songhua River (SSHR) basin in China, obtained during two years (2012-2013) of monitoring of 10 physicochemical parameters at 15 different sites. The results showed that most of physicochemical parameters varied significantly among the sampling sites. Three significant groups, highly polluted (HP), moderately polluted (MP) and less polluted (LP), of sampling sites were obtained through Hierarchical agglomerative CA on the basis of similarity of water quality characteristics. DA identified pH, F, DO, NH₃-N, COD and VPhs were the most important parameters contributing to spatial variations of surface water quality. However, DA did not give a considerable data reduction (40% reduction). PCA/FA resulted in three, three and four latent factors explaining 70%, 62% and 71% of the total variance in water quality data sets of HP, MP and LP regions, respectively. FA revealed that the SSHR water chemistry was strongly affected by anthropogenic activities (point sources: industrial effluents and wastewater treatment plants; non-point sources: domestic sewage, livestock operations and agricultural activities) and natural processes (seasonal effect, and natural inputs). PCA/FA in the whole basin showed the best results for data reduction because it used only two parameters (about 80% reduction) as the most important parameters to explain 72% of the data variation. Thus, this work illustrated the utility of multivariate statistical techniques for analysis and interpretation of datasets and, in water quality assessment, identification of pollution sources/factors and understanding spatial variations in water quality for effective stream water quality management.

The equilibrium adsorption isotherm and kinetic of the sorption process for W and Mo on macro chelating resin D403 were investigated on single Na₂MoO₄ and Na₂WO₄ solutions. The sorption isotherm results show that the adsorption process of W obeys the Freundlich model very well whereas the exchange process with Mo approximately follows the Henry model. The kinetic experiments show that the intraparticle diffusion process was the rate-determining step for W sorption on the resin, and the corresponding activation energy is calculated to be 21.976 kJ/mol.

A suitable and efficient flotation collector at normal atmospheric temperature for Donganshan iron ore was developed. A new chelate collector W-2 was synthesized. At 30 °C, condition flotation tests on mixed magnetic concentrate of Donganshan sintering plant established the best reagent system. With the optimum reagent system, one direct flotation and one reverse flotation including one roughing, one cleaning and two scavenging stages have been conducted. After closed-circuit flotation, excellent indices were obtained with grade of siderite concentrate of 36.49%, recovery rate of 10.65%, and loss on ignition of 11.17%, and the grade of hematite concentrate reached 66.27%, with recovery rate of 78.25%, tailing grade of 16.22%, and recovery rate of 11.10%. To analyze the mechanism of action from W-2 to quartz and siderite, zeta potential and FTIR spectra were detected. Results showed that after reaction with W-2, the zeta potential of quartz and siderite evidently changed, which resulted from hydrogen bond between quartz and W-2, and a certain chemical action between siderite and W-2. In addition, the electronegativity equalization principle was used to calculate electronegativity of active adsorption sites and analysis on reagent molecular structure showed that W-2 molecule had five active adsorption sites. Results showed that the electronegativity of atoms N and O in W-2 presented a substantial increase, and the synergy of atomic sites allowed considerable enhancement of collecting ability.

Titania coating of multi wall carbon nano tube (MWCNT) was carried out by sol-gel method in order to improve its photo catalytic properties. The effect of MWCNT/TiO₂ mass to volume ratio on adsorption ability, reaction rate and photo-catalytic removal efficiency of dibenzothiophene (DBT) from n-hexane solution was investigated using a 9 W UV lamp. The results show that the addition of nanotubes improves the photo-catalytic properties of TiO₂ by two factors; however, the DBT removal rate versus MWCNT content is found to follow a bimodal pattern. Two factors are observed to affect the removal rate of DBT and produce two optimum values for MWCNT content. First, large quantities of MWCNTs prevent light absorption by the solution and decrease removal efficiency. By contrast, a low dosage of MWCNT causes recombination of the electron holes, which also decreases the DBT removal rate. The optimum MWCNT contents in the composite are found to be 0.25 g and 0.75 g MWCNT per 80 mL of sol.

Hejiangkou W-Sn-polymetallic deposit is a newly found deposit in Xitian ore field, one of the important and large scale W-Sn-polymetallic ore fields in the middle segment of Nanling metallogenic zone. Re-Os isotope dating was used on three molybdenite samples from Hejiangkou deposit to determine the ore forming period. The result is (224.9±2.6)Ma-(225±3.1)Ma and isochron age is (225.5±3.6)Ma. The field geological observations, geochronological data and optical petrography indicated that Hejiangkou deposit underwent multi-period of superimposed mineralization. It can be differentiated into three periods composed of six mineralization stages. The first period is the initial period for hydrothermal metasomatism and metal element enrichment during Indosinian Epoch. Further enrichment, strong brittle fracturing and hydrothermal metasomatism, remobilization and superimposition happened in the second period, during early Yanshanian. It is the major mineralization period of Hejiangkou deposit and can be subdivided into four mineralization stages, namely the skarn stage, oxide stage, high-temperature sulfide stage and low-temperature sulfide stage. And the third period is the mineralization period of a porphyry-skarn system related to the emplacement of the granite porphyry dyke. As minerogenic epoch of Hejiangkou deposit is similar with Hehuaping deposit, they show the possibility of Indosinian mineralization event in Nanling metallogenic zone. It can be an important perspective in any future mineral exploration in the same metallogenic zone.

The problem of diving control for an underactuated unmanned undersea vehicle (UUV) considering the presence of parameters perturbations and wave disturbances was addressesed. The vertical motion of an UUV was divided into two noninteracting subsystems for surge velocity control and diving. To stabilize the vertical motion system, the surge velocity and the depth control controllers were proposed using backstepping technology and an integral-fast terminal sliding mode control (IFTSMC). It is proven that the proposed control scheme can guarantee that all the error signals in the whole closed-loop system globally converge to the sliding surface in finite time and asymptotically converge to the origin along the sliding surface. With a unified control parameters for different motion states, a series of numerical simulation results illustrate the effectiveness of the above designed control scheme, which also shows strong robustness against parameters perturbations and wave disturbances.

In order to control the growth of space debris, a novel tethered space robot (TSR) was put forward. After capture,the platform, tether, and target constituted a tethered combination system. General nonlinear dynamics of the tethered combination system in the post-capture phase was established with the consideration of the attitudes of two spacecrafts and the quadratic nonlinear elasticity of the tether. The motion law of the tethered combination in the deorbiting process with different disturbances was simulated and discussed on the premise that the platform was only controlled by a constant thrust force. It is known that the four motion freedoms of the tethered combination are coupled with each other in the deorbiting process from the simulation results. A noticeable phenomenon is that the tether longitudinal vibration does not decay to vanish even under the large tether damping with initial attitude disturbances due to the coupling effect. The approximate analytical solutions of the dynamics for a simplified model are obtained through the perturbation method. The condition of the inter resonance phenomenon is the frequency ratio λ₁=2. The case study shows good accordance between the analytical solutions and numerical results, indicating the effectiveness and correctness of approximate analytical solutions.

Collective pitch control and individual pitch control algorithms were present for straight-bladed vertical axis wind turbine to improve the self-starting capacity. Comparative analysis of straight-bladed vertical axis wind turbine(SB-VAWT) with or without pitch control was conducted from the aspects of aerodynamic force, flow structure and power coefficient. The computational fluid dynamics (CFD) prediction results show a significant increase in power coefficient for SB-VAWT with pitch control. According to the aerodynamic forces and total torque coefficient obtained at various tip speed ratios (TSRs), the results indicate that the blade pitch method can increase the power output and decrease the deformation of blade; especially, the total torque coefficient of blade pitch control at TSR 1.5 is about 2.5 times larger than that of fixed pitch case. Furthermore, experiment was carried out to verify the feasibility of pitch control methods. The results show that the present collective pitch control and individual pitch control methods can improve the self-starting capacity of SB-VAWT, and the former is much better and its proper operating TSRs ranges from 0.4 to 0.6.

The center cutter of a hard rock tunnel boring machine (TBM) is installed on the cutterhead at a small radius and thus bears complex side force. Given this fact, the formation mechanism and change law of the side force suffered by the center cutter were studied. Based on the rock shear failure criterion in combination with the lateral rolling width, a model for predicting the average side force was set up. Besides, a numerical analysis model of the rock fragmentation of the center cutter was established, and the instantaneous load changing features were investigated. Results shows that the inner side of the center cutter can form lateral rolling annulus in rock during the rotary cutting process. The smaller the installation radius is, the greater the cutter side force will be. In a working condition, the side force of the innermost center cutter is 11.66 kN, while it decreases sharply when installation radius increases. Variation tends to be gentle when installation radius is larger than 500 mm, and the side force of the outermost center cutter is reduced to 0.74 kN.

A magnet is an important component of a speaker, as it makes the coil move back forth, and it is commonly used in mobile information terminals. Defects may appear on the surface of the magnet while cutting it into smaller slices, and hence, automatic detection of surface cutting defect detection becomes an important task for magnet production. In this work, an image-based detection system for magnet surface defect was constructed, a Fourier image reconstruction based on the magnet surface image processing method was proposed. The Fourier transform was used to get the spectrum image of the magnet image, and the defect was shown as a bright line in it. The Hough transform was used to detect the angle of the bright line, and this line was removed to eliminate the defect from the original gray image; then the inverse Fourier transform was applied to get the background gray image. The defect region was obtained by evaluating the gray-level differences between the original image and the background gray image. Further, the effects of several parameters in this method were studied and the optimized values were obtained. Experiment results show that the proposed method can detect surface cutting defects in a magnet automatically and efficiently.

In order to reveal the force transmission features of the granules in the solid granule medium forming (SGMF) technology, the frictional characteristics of the non-metallic granule medium (NGM) under high pressure were investigated by tests and simulations. And the relevant changing curves of the internal friction coefficient of the granular system under different normal pressures were obtained by self-designed shear test. By the granule volume compression test, the accurate discrete element simulation parameters were obtained, based on this, the discrete element method (DEM) was adopted to reveal the evolution law of the NGM granules movement in the sample shear process from the microscopic view. Based on the DEM, the influence of granule diameter, surface friction coefficient, normal pressure and shear velocity on the internal friction coefficient of the granular system were studied. And the parameters were conducted to be dimensionless by introducing the inertia coefficient. Finally, the expression showing power-law relationship of inertia coefficient, surface friction coefficient and internal friction coefficient is obtained.

Improving rollover and stability of the vehicles is the indispensable part of automotive research to prevent vehicle rollover and crashes. The main objective of this work is to develop active control mechanism based on fuzzy logic controller (FLC) and linear quadratic regulator (LQR) for improving vehicle path following, roll and handling performances simultaneously. 3-DOF vehicle model including yaw rate, lateral velocity (lateral dynamic) and roll angle (roll dynamic) were developed. The controller produces optimal moment to increase stability and roll margin of vehicle by receiving the steering angle as an input and vehicle variables as a feedback signal. The effectiveness of proposed controller and vehicle model were evaluated during fishhook and single lane-change maneuvers. Simulation results demonstrate that in both cases (FLC and LQR controllers) by reducing roll angle, lateral acceleration and side slip angles remain under 0.6g and 4° during maneuver, which ensures vehicle stability and handling properties. Finally, the sensitivity and robustness analysis of developed controller for varying longitudinal speeds were investigated.

In order to investigate and predict the material properties of curved surface AISI 1045 steel component during spot continual induction hardening (SCIH), a 3D model for curved surface workpieces which coupled electromagnetic, temperature and phase transformation fields was built by finite element software ANSYS. A small size inductor and magnetizer were used in this model, which can move along the top surface of workpiece flexibly. The effect of inductor moving velocity and workpiece radius on temperature field was analyzed and the heating delay phenomenon was found through comparing the simulated results. The temperature field results indicate that the heating delay phenomenon is more obvious under high inductor moving velocity condition. This trend becomes more obvious if the workpiece radius becomes larger. The predictions of microstructure and micro-hardness distribution were also carried out via this model. The predicted results show that the inductor moving velocity is the dominated factor for the distribution of 100% martensite region and phase transformation region. The influencing factor of workpiece radius on 100% martensite region and phase transformation region distribution is obvious under relatively high inductor moving velocity but inconspicuous under relatively low inductor moving velocity.

A mathematical approach was proposed to investigate the impact of high penetration of large-scale photovoltaic park (LPP) on small-signal stability of a power network and design of hybrid controller for these units. A systematic procedure was performed to obtain the complete model of a multi-machine power network including LPP. For damping of oscillations focusing on inter-area oscillatory modes, a hybrid controller for LPP was proposed. The performance of the suggested controller was tested using a 16-machine 5-area network. The results indicate that the proposed hybrid controller for LPP provides sufficient damping to the low-frequency modes of power system for a wide range of operating conditions. The method presented in this work effectively indentifies the impact of increased PV penetration and its controller on dynamic performance of multi-machine power network containing LPP. Simulation results demonstrate that the model presented can be used in designing of essential controllers for LPP.

Ensemble learning is a wildly concerned issue. Traditional ensemble techniques are always adopted to seek better results with labeled data and base classifiers. They fail to address the ensemble task where only unlabeled data are available. A label propagation based ensemble (LPBE) approach is proposed to further combine base classification results with unlabeled data. First, a graph is constructed by taking unlabeled data as vertexes, and the weights in the graph are calculated by correntropy function. Average prediction results are gained from base classifiers, and then propagated under a regularization framework and adaptively enhanced over the graph. The proposed approach is further enriched when small labeled data are available. The proposed algorithms are evaluated on several UCI benchmark data sets. Results of simulations show that the proposed algorithms achieve satisfactory performance compared with existing ensemble methods.

Fault diagnosis plays an important role in complicated industrial process. It is a challenging task to detect, identify and locate faults quickly and accurately for large-scale process system. To solve the problem, a novel MultiBoost-based integrated ENN (extension neural network) fault diagnosis method is proposed. Fault data of complicated chemical process have some difficult-to-handle characteristics, such as high-dimension, non-linear and non-Gaussian distribution, so we use margin discriminant projection(MDP) algorithm to reduce dimensions and extract main features. Then, the affinity propagation (AP) clustering method is used to select core data and boundary data as training samples to reduce memory consumption and shorten learning time. Afterwards, an integrated ENN classifier based on MultiBoost strategy is constructed to identify fault types. The artificial data sets are tested to verify the effectiveness of the proposed method and make a detailed sensitivity analysis for the key parameters. Finally, a real industrial system—Tennessee Eastman (TE) process is employed to evaluate the performance of the proposed method. And the results show that the proposed method is efficient and capable to diagnose various types of faults in complicated chemical process.

The wireless capsule endoscope, as a small electronic device, has conquered some limitations of traditional wired diagnosing tools, such as the uncomfortableness of the cables for the patient and the inability to examine the very convoluted small intestine section. However, this technique is still encountering a lot of practical challenges and is looking for feasible improvements. This work investigates the RF performance of the wireless capsule endoscope system by studying the electromagnetic (EM) wave propagation within the human body. A wireless capsule endoscopy transmission channel model is constructed to serve the purpose of investigating signal attenuations according to the relative position between the transmitter and the receiver. Within 300-500 MHz, the S21 results are regular and do not display any sudden changes, which allows a suitable expression to be derived for S₂₁ in terms of frequency and offset. The results provide useful information for capsule localization.

Vestibulo-ocular reflex (VOR) is an important biological reflex that controls eye movement to ensure clear vision while the head is in motion. Nowadays, VOR measurement is commonly done with a video head impulse test based on a velocity gain algorithm or a position gain algorithm, in which velocity gain is a VOR calculation on head and eye velocity, whereas position gain is calculated from head and eye position. The aim of this work is first to compare the two algorithms’ performance and to detect covert catch-up saccade, then to propose a stand-alone recommendation application for the patient’s diagnosis. In the first experiment, for ipsilesional and contralesional sides, the calculated position gain (0.94±0.17) is higher than velocity gain (0.84±0.19). Moreover, gain asymmetry of both lesion and intact sides using velocity gain is mostly higher than that from using position gain (four out of five subjects). Consequently, for subjects who have unilateral vestibular neuritis diagnosed from clinical symptoms and a vestibular function test, vestibular weakness is depicted by velocity gain much better than by position gain. Covert catch-up saccade and position gain then are used as inputs for recommendation applications.

The H_∞ performance analysis and controller design for linear networked control systems (NCSs) are presented. The NCSs are considered a linear continuous system with time-varying interval input delay by assuming that the sensor is time-driven and the logic Zero-order-holder (ZOH) and controller are event-driven. Based on this model, the delay interval is divided into two equal subintervals for H_∞ performance analysis. An improved H_∞ stabilization condition is obtained in linear matrix inequalities (LMIs) framework by adequately considering the information about the bounds of the input delay to construct novel Lyapunov–Krasovskii functionals (LKFs). For the purpose of reducing the conservatism of the proposed results, the bounds of the LKFs differential cross terms are properly estimated without introducing any slack matrix variables. Moreover, the H_∞ controller is reasonably designed to guarantee the robust asymptotic stability for the linear NCSs with an H_∞ performance level γ. Numerical simulation examples are included to validate the reduced conservatism and effectiveness of our proposed method.

For efficient utilization of a limited geothermal resource in practical projects, the cycle parameters were comprehensively analyzed by combining with the heat transfer performance of the plate heat exchanger, with a variation of flowrate of R245fa. The influence of working fluid flowrate on a 500W ORC system was investigated. Adjusting the working fluid flowrate to an optimal value results in the most efficient heat transfer and hence the optimal heat transfer parameters of the plate heat exchanger can be determined. Therefore, for the ORC systems, optimal working fluid flowrate should be controlled. Using different temperature hot water as the heat source, it is found that the optimal flowrate increases by 6-10 L/h with 5 °C increment of hot water inlet temperature. During experiment, lower degree of superheat of the working fluid at the outlet the plate heat exchanger may lead to unstable power generation. It is considered that the plate heat exchanger has a compact construction which makes its bulk so small that liquid mixture causes the unstable power generation. To avoid this phenomenon, the flow area of plate heat exchanger should be larger than the designed one. Alternatively, installing a small shell and tube heat exchanger between the outlet of plate heat exchanger and the inlet of expander can be another solution.

The disturbance due to mechanical and thermal sources in saturated porous media with incompressible fluid for two-dimensional axi-symmetric problem is investigated. The Laplace and Hankel transforms techniques are used to investigate the problem. The concentrated source and source over circular region have been taken to show the utility of the approach. The transformed components of displacement, stress and pore pressure are obtained. Numerical inversion techniques are used to obtain the resulting quantities in the physical domain and the effect of porosity is shown on the resulting quantities. All the field quantities are found to be sensitive towards the porosity parameters. It is observed that porosity parameters have both increasing and decreasing effect on the numerical values of the physical quantities. Also the values of the physical quantities are affected by the different boundaries. A special case of interest is also deduced.

Based on nonlinear failure criterion, a three-dimensional failure mechanism of the possible collapse of deep tunnel is presented with limit analysis theory. Support pressure is taken into consideration in the virtual work equation performed under the upper bound theorem. It is necessary to point out that the properties of surrounding rock mass plays a vital role in the shape of collapsing rock mass. The first order reliability method and Monte Carlo simulation method are then employed to analyze the stability of presented mechanism. Different rock parameters are considered random variables to value the corresponding reliability index with an increasing applied support pressure. The reliability indexes calculated by two methods are in good agreement. Sensitivity analysis was performed and the influence of coefficient variation of rock parameters was discussed. It is shown that the tensile strength plays a much more important role in reliability index than dimensionless parameter, and that small changes occurring in the coefficient of variation would make great influence of reliability index. Thus, significant attention should be paid to the properties of surrounding rock mass and the applied support pressure to maintain the stability of tunnel can be determined for a given reliability index.

Irregular plates are very common structures in engineering, such as ore structures in mining. In this work, the Galerkin solution to the problem of a Kirchhoff plate lying on the Winkler foundation with two edges simply supported and the other two clamped supported is derived. Coordinate transformation technique is used during the solving process so that the solution is suitable to irregular shaped plates. The mechanical model and the solution proposed are then used to model the crown pillars between two adjacent levels in Sanshandao gold mine, which uses backfill method for mining operation. After that, an objective function, which takes security, economic profits and filling effect into consideration, is built to evaluate design proposals. Thickness optimizations for crown pillars are finally conducted in both conditions that the vertical stiffness of the foundation is known and unknown. The procedure presented in the work provides the guidance in thickness designing of complex shaped crown pillars and the preparation of backfill materials, thus to achieve the best balance between security and profits.

In a wind-vehicle-bridge (WVB) system, there are various interactions among wind, vehicle and bridge. The mechanism for coupling vibration of wind-vehicle-bridge systems is explored to demonstrate the effects of fundamental factors, such as mean wind, fluctuating wind, buffeting, rail irregularities, light rail vehicle vibration and bridge stiffness. A long cable-stayed bridge which carries light rail traffic is regarded as a numerical example. Firstly, a finite element model is built for the long cable-stayed bridge. The deck can generally be idealized as three-dimensional spine beam while cables are modeled as truss elements. Vehicles are modeled as mass-spring-damper systems. Rail irregularities and wind fluctuation are simulated in time domain by spectrum representation method. Then, aerodynamic loads on vehicle and bridge deck are measured by section model wind tunnel tests. Eight vertical and torsional flutter derivatives of bridge deck are identified by weighting ensemble least-square method. Finally, dynamic responses of the WVB system are analyzed in a series of cases. The results show that the accelerations of the vehicle are excited by the fluctuating wind and the track irregularity to a great extent. The transverse forces of wheel axles mainly depend on the track irregularity. The displacements of the bridge are predominantly determined by the mean wind and restricted by its stiffness. And the accelerations of the bridge are enlarged after adding the fluctuating wind.

Congestion pricing is an important component of urban intelligent transport system. The efficiency, equity and the environmental impacts associated with road pricing schemes are key issues that should be considered before such schemes are implemented. This paper focuses on the cordon-based pricing with distance tolls, where the tolls are determined by a nonlinear function of a vehicles’ travel distance within a cordon, termed as toll charge function. The optimal tolls can give rise to: 1) higher total social benefits, 2) better levels of equity, and 3) reduced environmental impacts (e.g., less emission). Firstly, a deterministic equilibrium (DUE) model with elastic demand is presented to evaluate any given toll charge function. The distance tolls are non-additive, thus a modified path-based gradient projection algorithm is developed to solve the DUE model. Then, to quantitatively measure the equity level of each toll charge function, the Gini coefficient is adopted to measure the equity level of the flows in the entire transport network based on equilibrium flows. The total emission level is used to reflect the impacts of distance tolls on the environment. With these two indexes/measurements for the efficiency, equity and environmental issues as well as the DUE model, a multi-objective bi-level programming model is then developed to determine optimal distance tolls. The multi-objective model is converted to a single level model using the goal programming. A genetic algorithm (GA) is adopted to determine solutions. Finally, a numerical example is presented to verify the methodology.