The superplasticity of Al-6Mg-0.4Mn-0.25Sc-0.12Zr and Al-6Mg-0.4Mn-0.25Er-0.12Zr (mass fraction, %) alloys sheet was investigated, and the effect of Sc and Er was discussed. The results show that the superplastic ductilities of Al-Mg-Mn-Sc-Zr alloy was higher than that of Al-Mg-Mn-Er-Zr alloy at a wide temperature range of 400-540 °C and high strain rate range of 1.67×10^-4-1.67×10^-1 s^-1. A maximum elongation 673% is obtained at 520 °C and 1.67×10^-3 s^-1 in the Sc-containing alloy; while the Er-containing alloy only gets a maximum elongation 253% at 520 °C and 1.67×10^-3 s^-1. Moreover, the average stress exponent of Sc-containing alloy is about 2.84, which is smaller than that of Er-containing alloy (3.64). Besides, the activation energies of the Sc-containing and Er-containing alloy are 84.8 kJ/mol and 87.2 kJ/mol, respectively. It is indicated that grain boundary sliding is the dominant mechanism during tensile deformation. According to microstructure examination, the better superplasticity of Sc-containing alloy may be attributed to the presence of Al₃(Sc, Zr) dispersoids, which can inhibit recrystallization and grain growth effectively.

Three experimental single crystal superalloys with 0%Nb, 0.5%Nb, 1.0%Nb were cast in the directionally solidified furnace, while other alloying element contents were basically kept unchanged. The effect of Nb on the microstructure, stability at 1100 °C and stress rupture properties at 1070 °C and 160 MPa of the single crystal superalloy were investigated. The experiment results show that the primary dendrite arm spacing decreases and the volume fraction of γ/γ′ eutectic of the alloy increases with the increase of Nb content in the as-cast microstructures. The size of γ′ phase particles becomes small and uniform and the cubic shape does not obviously change with the increase of Nb content. The precipitating rate and volume fraction of TCP phases increase significantly with the increase of Nb content in the process of long term aging at 1100 °C. The stress rupture lives increase and elongation decreases with increasing Nb content at 1070 °C/160 MPa. At last, the relationship between the microstructures stability, stress rupture properties of the alloy and Nb content is discussed based on JMatPro software and the lastest relevant database for single crystal superalloy.

The plates of AA5086 aluminium alloy were joined together by friction stir welding at a fixed rotation speed of 1000 r/min various welding speeds ranging from 63 to 100 mm/min. Corrosion behavior of the parent alloy (PA), the heat affected zone (HAZ), and the weld nugget zone (WNZ) of the joints were studied in 3.5% (mass fraction) aerated aqueous NaCl solution by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The corrosion susceptibility of the weldments increases when the welding speed increases to 63 and 100 mm/min. However, the value of corrosion rate in the weldments is lower than that in the PA. Additionally, the corrosion current density increases with increasing the welding speed in the HAZ and the WNZ. On the contrary, the corrosion potential in the WNZ appears more positive than in the HAZ with decreasing the welding speed. The WNZ exhibits higher resistance compared to the HAZ and the PA as the welding speed decreases. The results obtained from the EIS measurements suggest that the weld regions have higher corrosion resistance than the parent alloy. With increasing the welding speed, the distribution and extent of the corroded areas in the WNZ region are lower than those of the HAZ region. In the HAZ region, in addition to the pits in the corroded area, some cracks can be seen around the corroded areas, which confirms that intergranular corrosion is formed in this area. The alkaline localized corrosion and the pitting corrosion are the main corrosion mechanisms in the corroded areas within the weld regions. Crystallographic pits are observed within the weld regions.

A hydrometallurgical process for tungsten extraction and recovery from scheelite is reported. The technology includes leaching scheelite using phosphoric acid as chelating agent in nitric acid solutions, extracting tungsten by solvent extraction and reusing leaching agent. In the leaching process, affecting factors, such as temperature, leaching time, nitric acid and dosage of phosphoric acid, were examined on recovery of tungsten. Results show that more than 97% of tungsten could be extracted under conditions of leaching temperature of 80-90 °C, HNO₃ concentration of 3.0-4.0 mol/L, liquild-to-soild ratio of 10:1, H₃PO₄ dosage of 3 stoichiometric ratio and leaching time of 3 h. Solvent extraction was then employed for the W recovery from the leachate with a organic system of 40% (v/v) N235, 30% (v/v) TBP, and 30% sulfonated kerosene. Approximately 99.93% of W was extracted and ammonium tungstate solution containing 193 g/L W was obtained with a stripping rate of 98.10% under the optimized conditions.

Isothermal experiments on the reduction of Fe₂O₃-Cr₂O₃-NiO (molar ratio of Fe-to-Cr-to-Ni is 3:2:2) by graphite were carried out at 1350–1550°C, and effects of various factors on reduction degree were studied. The results show that the reaction rate of the Fe₂O₃-Cr₂O₃-NiO system is fast during the initial period (reduction degree, α<38%), and then the rate decreases until the end of the reduction. Factors such as temperature, carbon content, sample size have a more significant effect during the final stage (α>38%). The metallic product formed at the initial stage (a Fe-Ni alloy) greatly promotes the reduction of Cr₂O₃ at the final stage. Further, during the reduction of Fe₂O₃-Cr₂O₃-NiO by carbon, interfacial reaction is the rate-controlling step and g(α)=1-(1-α)^0.5 is the reaction mechanism for the initial stage, whereas two-dimensional diffusion is the rate-controlling step and f(α)=α+(1-α)ln(1-α) is the reaction mechanism for the final stage. The apparent activation energies are 55.43 kJ/mol and 174.54 kJ/mol for the initial and the final stages, respectively.

Reduction smelting of the bismuth oxide residue from pressure leaching of bismuth sulfide was investigated in the FeO-SiO₂-CaO ternary slag system. The results show that all the recovery ratios of Bi, Ag, Cu and Pb increase with the increase of reductive coal proportion, reaction temperature and time, while too much reductive coal would help Fe enter metal phase; CaO/SiO₂ and FeO/SiO₂ of the chosen slag system should be 0.5-0.75 and 1.25-1.75, respectively, for the reason that the slag system has the optimum mobility and is beneficial for the recovery of metals. The corresponding optimum conditions are determined as follows: the added coal proportion is 7% of the leaching residue, CaO/SiO₂ mass ratio in the chosen slag system is 0.5 and FeO/SiO₂ is 1.5, the reaction temperature is 1300 °C and the reaction time is 40 min. Under the above conditions, the recovery ratios of Bi, Ag, Cu and Pb are 99.6%, 99.8%, 97.0% and 97.3%, respectively.

The mathematical topological rule was applied to plot the predominance area diagram. Based on the analysis of the mutually conjugated, only two diagrams were the best topological embryonic graphs to build the predominance area diagram of Me-S-O system. Combined with topological rules and thermodynamic calculation, four relation-diagrams were denoted as α and β stable and unstable plane-topological diagrams, which were plotted for the Pb-S-O system and Zn-S-O system. The results show that β stable plane-topological diagram of Pb-S-O system and α stable one of Zn-S-O system are in accordance with the traditional predominance area diagram, which indicates that it is feasible to plot the predominance area diagram based on mathematical topological rules. Meanwhile, α unstable plane-topological diagram of Pb-S-O system can elucidate the phenomenon that metallic lead exists in higher oxygen and sulfur pressure area in modern bath smelting furnace. The mathematical topological rules broaden the application scope of the predominance area diagram and enrich the practice of its plotting.

Flotation behavior and adsorption mechanism of octyl hydroxamic acid (OHA) on wolframite were investigated through flotation experiments, adsorption tests, zeta-potential measurements, infrared spectroscopy and solution chemistry calculations. Results of flotation and adsorption experiments show that the maximum values of flotation recovery and adsorption capacity occur around pH 9. In term of the solution chemistry calculations, the concentration of metal hydroxamate is greater than that of metal tungstate and metal hydroxyl, and metal hydroxamate compounds are identified to be the main species on wolframite surface at pH region of 8-10, contributing to the increase of OHA adsorption and flotation performance. Results of zeta-potential and IR spectra demonstrate that OHA adsorbs onto wolframite surface by chemisorptions. Hydroxamate ions can bond with Mn²⁺/Fe²⁺ cations of wolframite surface, forming metal hydroxamate compounds, which is a key factor in inducing the hydrophobicity of wolframite under the conditions of maximum flotation.

The characteristics of the zeolite modified by microwave and sodium acetate and its sorption of ammonia-nitrogen from simulated water sample were investigated. The results show that the modified zeolite by microwave-sodium acetate (SMMZ) has a high sorption efficiency and removal performance. The ammonia-nitrogen removal rate of SMMZ reaches 92.90%. The surface of SMMZ becomes loose and some pores appear, the specific surface area, total pore volume and average pore diameter increase after modification. Compared to the natural zeolite, SMMZ has a more concentrated pore size distribution in the range of 0-10 nm. The cation exchange capacity (CEC) of SMMZ is higher than that of the natural zeolite. And the ammonia nitrogen removal rate is consistent with the change of CEC. The SMMZ possesses rapid sorption and slow balance characteristics and ammonia-nitrogen sorption is consistent with both Langmuir adsorption isotherm model and Freundlich adsorption isotherm model. The adsorption kinetics of ammonia-nitrogen follows the pseudo-second order kinetic model.

The ability of a wet swale, constructed in an area of poor soil permeability, to manage runoff from a roadway was monitored through 27 storm events over a period of 8 months. During the monitoring period, the wet swale reduced the total runoff volume by 50.4% through exfiltration and evapotranspiration. The wet swale significantly decreased the influent pollutant concentrations, and the effluent mean concentrations of total suspended solids, total phosphorus, chemical oxygen demand, ammonium, oxidized nitrogen, and total nitrogen in the effluent were 31 mg/L, 0.10 mg/L, 29 mg/L, 0.52 mg/L, 0.35 mg/L and 1.28 mg/L, respectively. Pollutant loads were also substantially reduced from 70% to 85%. Plant uptake played an important role in nutrient removal in the wet swale. Approximately half of the nitrogen (53.8%) and phosphorus (51.5%) that entered the wet swale was incorporated in above-ground plants. It is shown that wet swales are useful for managing runoff from roads in areas of poor soil permeability.

This work addresses the problem of self-excited vibration, which degrades the stability of the levitation control, decreases the ride comfort, and restricts the construction cost of maglev system. Firstly, a minimum model containing a flexible bridge and a single levitation unit is presented. Based on the simplified model, the principle underlying the self-excited vibration is explored. After investigations about the energy transmission between the levitation system and bridge, it is concluded that the increment of modal damping can dissipate the accumulated energy by the bridge and the self-excited vibration may be avoided. To enlarge the equivalent modal damping of bridge, the sky-hooked damper is adopted. Furthermore, to avoid the hardware addition of real sky-hooked damper, considering the fact that the electromagnet itself is an excellent actuator that is capable of providing sufficiently fast and large force acting on the bridge to emulate the influence of the real sky-hooked damper, the technique of the virtual sky-hooked damper is proposed. The principle underlying the virtual sky-hooked damper by electromagnet is explored and the vertical velocity of bridge is estimated. Finally, numerical and experimental results illustrating the stability improvement of the vehicle-bridge interaction system are provided.

Error codes induced by M-ary modulation and modulation selection in network-based control systems are studied. It is the first time the issue of error codes induced by M-ary modulation is addressed in control field. In network-based control systems, error codes induced by noisy channel can significantly decrease the quality of control. To solve this problem, the network-based control system with delay and noisy channel is firstly modeled as an asynchronous dynamic system (ADS). Secondly, conditions of packet with error codes (PEC) loss rate by using M-ary modulation are obtained based on dynamic output feedback scheme. Thirdly, more importantly, the selection principle of M-ary modulation is proposed according to the measured signal-to-noise ratio (SNR) and conditions of PEC loss rate. Finally, system stability is analyzed and controller is designed through Lyapunov function and linear matrix inequality (LMI) scheme, and numerical simulations are made to demonstrate the effectiveness of the proposed scheme.

It is illegal to spread and transmit pornographic images over internet, either in real or in artificial format. The traditional methods are designed to identify real pornographic images and they are less efficient in dealing with artificial images. Therefore, criminals turn to release artificial pornographic images in some specific scenes, e.g., in social networks. To efficiently identify artificial pornographic images, a novel bag-of-visual-words based approach is proposed in the work. In the bag-of-words (BoW) framework, speeded-up robust feature (SURF) is adopted for feature extraction at first, then a visual vocabulary is constructed through K-means clustering and images are represented by an improved BoW encoding method, and finally the visual words are fed into a learning machine for training and classification. Different from the traditional BoW method, the proposed method sets a weight on each visual word according to the number of features that each cluster contains. Moreover, a non-binary encoding method and cross-matching strategy are utilized to improve the discriminative power of the visual words. Experimental results indicate that the proposed method outperforms the traditional method.

Support vector machine (SVM) has a good application prospect for speech recognition problems; still optimum parameter selection is a vital issue for it. To improve the learning ability of SVM, a method for searching the optimal parameters based on integration of predator prey optimization (PPO) and Hooke-Jeeves method has been proposed. In PPO technique, population consists of prey and predator particles. The prey particles search the optimum solution and predator always attacks the global best prey particle. The solution obtained by PPO is further improved by applying Hooke-Jeeves method. Proposed method is applied to recognize isolated words in a Hindi speech database and also to recognize words in a benchmark database TI-20 in clean and noisy environment. A recognition rate of 81.5% for Hindi database and 92.2% for TI-20 database has been achieved using proposed technique.

In order to improve tracking accuracy when initial estimate is inaccurate or outliers exist, a bearings-only tracking approach called the robust range-parameterized cubature Kalman filter (RRPCKF) was proposed. Firstly, the robust extremal rule based on the pollution distribution was introduced to the cubature Kalman filter (CKF) framework. The improved Turkey weight function was subsequently constructed to identify the outliers whose weights were reduced by establishing equivalent innovation covariance matrix in the CKF. Furthermore, the improved range-parameterize (RP) strategy which divides the filter into some weighted robust CKFs each with a different initial estimate was utilized to solve the fuzzy initial estimation problem efficiently. Simulations show that the result of the RRPCKF is more accurate and more robust whether outliers exist or not, whereas that of the conventional algorithms becomes distorted seriously when outliers appear.

A sliding mode and active disturbance rejection control (SM-ADRC) was employed to regulate the speed of a permanent magnet synchronous motor (PMSM).The major advantages of the proposed control scheme are that it can maintain the original features of ADRC and make the parameters of ADRC transition smoothly. The proposed control scheme also ensures speed control accuracy and improves the robustness and anti-load disturbance ability of the system. Moreover, through the analysis of a d-axis current output equation, a novel current-loop SM-ADRC is presented to improve the system’s dynamic performance and inner ability of anti-load disturbance. Results of a simulation and experiments show that the improved sliding-mode ADRC system has the advantages of fast response, small overshoot, small steady-state error, wide speed range and high control accuracy. It shows that the system has strong anti-interference ability to reduce the influence of variations in rotational inertia, load and internal parameters.

In order to realize safe and accurate homing of parafoil system, a multiphase homing trajectory planning scheme is proposed according to the maneuverability and basic flight characteristics of the vehicle. In this scenario, on the basis of geometric relationship of each phase trajectory, the problem of trajectory planning is transformed to parameter optimizing, and then auxiliary population-based quantum differential evolution algorithm (AP-QDEA) is applied as a tool to optimize the objective function, and the design parameters of the whole homing trajectory are obtained. The proposed AP-QDEA combines the strengths of differential evolution algorithm (DEA) and quantum evolution algorithm (QEA), and the notion of auxiliary population is introduced into the proposed algorithm to improve the searching precision and speed. The simulation results show that the proposed AP-QDEA is proven its superior in both effectiveness and efficiency by solving a set of benchmark problems, and the multiphase homing scheme can fulfill the requirement of fixed-points and upwind landing in the process of homing which is simple in control and facile in practice as well.

Sediments in the Liushagang Formation of Late Eocene form a group of key hydrocarbon play fairways in the Beibuwan Basin, South China Sea. As an important reservoir-forming combination, the Liushagang Formation consists of deltaic siliciclastic and show clear sedimentary cyclicity. According to paleontology research and stratigraphic correlation, the boundary between Liushagang Formation (Els) and Weizhou Formation (Ewz) is regarded as the Eocene-Oligocene boundary. The oxygen isotope dating for well cores from the top of the first Member of Liushagang Formation (Els1) and the bottom of the third Member of Weizhou Formation (Ewz3) give an isochron age of 35.2 Ma. Here, we use GR logging data as a paleoenvironmental proxy to conduct a detailed cyclostratigraphic study of the Els1 in the Bailian Sag, Fushan Depression. Power spectra, evolutionary fast Fourier transformation and wavelet analysis all reveal significant sedimentary cycles in Els1. The ratios of cycle wavelengths in these stratigraphic units are 21:5:2.8:1.2:1, and are interpreted as Milankovitch cycles of 400 ka and 96 ka eccentricity, 52 ka obliquity, 22 ka and 19 ka precession cycles, respectively. An astronomical time scale is established by tuning filtered 96 ka eccentricity cycles to a target curve of Well L2 in the Bailian Sag. Based on regional stratigraphic framework, combined with seismic, cores and logging data, the HST of the first member of the Liushagang Formation (Els1) delta in Well L2 was divided into six parasequence sets named Ps1-Ps6. According to the spectrum analysis by Simple Lomb periodogram from PAST program packages, the sediment accumulation rate of each parasequence sets first increased and then decreased as time went by. The sediment accumulation rate of Ps4 reached the maximum (0.127 m/ka) during the most prosperous period of delta prograding. Finally, the duration of each period of parasequence sets and more accurate geological age were calculated on the basis of sediment accumulation rate. The ages of each depth are precisely estimated and provide new constraints on the Late Eocene.

The sequence of the densification and hydrocarbon charging of the Xu2 reservoir in the Anyue–Hechuan area of Central Sichuan Basin is discussed. The diagenetic sequence is considered a time line to determine the historical relationship between the densification process and the hydrocarbon charging of the Xu2 reservoir in the study area: Early diagenetic stage B (the first stage of hydrocarbon charging, which was about 200–160 Ma ago, with a porosity of about 20%, consolidated and not tight) → middle diagenetic stage A (the second stage of hydrocarbon charging, which was about 140–120 Ma ago, with a porosity of 10%–20% and relatively tight) → middle diagenetic stage B (the third stage of hydrocarbon charging, which was about 20–5 Ma ago, with a porosity of 6%–10% and tight; However, fractures have developed). The study results prove that large-scale hydrocarbon charging and accumulation completed before the densification of the Xu2 reservoir, showing that the Upper Triassic Xujiahe Fm unconventional tight reservoir in the Sichuan Basin is prospective for exploration.

Subei-Huainan in the southeastern margin of the North China platform is a key area of convergence of China’s north-south stratigraphic correlation of Neoproterozoic. Due to the lack of fossils, the Neoproterozoic stratigraphic correlation is still a difficulty in this area. The division of Neoproterozoic strata and the establishment of the correlation framework of the stratigraphic sequences have been done through recognizing the regularity of meter-scale cycles by measuring the outcrop of Neoproterozoic strata and using the Fischer diagram and the sea-level curve of transgressive-regressive by the maximum flooding sedimentary and molar teeth carbonate sedimentary. The maximum flooding sedimentary which becomes cycle sequence comparison of sign is isochronous in the same basin and is a key of cycle sequence comparison although paleogeographic environment and sedimentary sequence may be different in the sedimentary strata of the same geologic time. Molars carbonates, having specific geological distrution time and depositional environment and mainly developing in the ramp environment of the platform edge in the 1500-650 Ma, are the new symbol of the stratigraphic correlation in the Neoproterozoic. Because of the missing of the fossil record, the maximum flooding and the molar-teeth carbonate sedimentary, as the new research ideas, are used in stratigraphic division and correlation.

The aim of this work is to establish volcanic seismic reflection configuration models in the rift basins of Northeast China from a new perspective, the volcanostratigraphic structure. Accordingly, the volcanostratigraphic structure of an outcrop near the Hailaier Rift Basin was analyzed to understand the characteristics and causal factors of physical boundaries. Further, 3D seismic reflection data and analysis of deep boreholes in the Songliao Rift Basin were used to establish the relationship between volcanic seismic reflection configurations and volcanostratigraphic structures. These studies suggested that in volcanic successions, physical boundaries coincide with volcanic boundaries, and their distributions are controlled by the stacking patterns of volcanic units. Therefore, volcanic seismic reflection configurations can be interpreted in terms of the stacking patterns of volcanic units. These are also referred to as general bedding patterns in volcanostratigraphy. Furthermore, four typical seismic reflection configurations were identified, namely, the chaotic, the parallel continuous, the hummocky, the multi-mound superimposed and the composite. The corresponding interpretation models comprised single massive unit, vertical, intersectional, lateral multi-mound, and composite stacking patterns. The hummocky and composite reflection configurations with intersectional and composite stacking patterns are the most favorable for the exploration of volcanic reservoirs in rift basins.

The laminated overburden model (LaModel) has been widely used for pillar design and stability analysis. As a boundary element program, the LaModel program is sensitive to the boundary condition, which should be considered before creating the model. To eliminate the boundary effect in a LaModel pillar stability analysis, a suitable boundary buffer zone is needed around the model edge. The radius of influence (R) and the abutment load extent (D) are two major factors that affect the stresses and displacements calculated in LaModel. To determine the optimum buffer zone extent, a database of case histories was analyzed using the LaModel program. Values for R and D were varied until a buffer zone having negligible influence on the pillar stability factor (SF) of the active mining zone (AMZ) was determined.

A series of laboratory experiments and PFC numerical simulations for rock-like material specimens containing two unparallel fissures were carried out. On the basis of experimental and numerical results, the stress-strain curves, mechanical properties, AE events, cracking behavior and energy characteristics were analyzed to reveal the macro-mechanical behavior and meso-mechanism of pre-fissured specimens under different loading rates. Investigated results show that: 1) When the loading rate is relatively low, the stress-strain curves show a brittle response. When the loading rate is relatively high, the curve shows a more ductile response. Both of the peak strength and elastic mudulus increase with the increase of loading rate, which can be expressed as power functions. 2) Four crack types are identified, i.e., tensile crack, shear crack, far-field crack and surface spalling. Moreover, the tensile crack, far-field crack and surface spalling are under tensile mechanism, while the shear crack is under shear mechanism. 3) The drops of the stress-strain curves all correspond to the crack initiation or coalescence, which is also linked to a sudden increasing in the accumulated micro-crack curve. 4) Both of the maximum bond force and energy have the similar trend with the increase of loading rate to peak strength, which indicates that the trend of peak strength can be explained by the meso-mechanics and energy.

Discontinuities constitute an integral part of rock mass and inherently affect its anisotropic deformation behavior. This work focuses on the equivalent elastic deformation of rock mass with multiple persistent joint sets. A new method based on the space geometric and mechanical properties of the modified crack tensor is proposed, providing an analytical solution for the equivalent elastic compliance tensor of rock mass. A series of experiments validate the capability of the compliance tensor to accurately represent the deformation of rock mass with multiple persistent joint sets, based on conditions set by the basic hypothesis. The spatially varying rules of the equivalent elastic parameters of rock mass with a single joint set are analyzed to reveal the universal law of the stratified rock mass.

The scattering-model-based (SMB) speckle filtering for polarimetric SAR (PolSAR) data is reasonably effective in preserving dominant scattering mechanisms. However, the efficiency strongly depends on the accuracies of both the decomposition and classification of the scattering properties. In addition, a relatively weak speckle reduction particularly in distributed media was reported in the related literatures. In this work, an improved SMB filtering strategy is proposed considering the aforementioned deficiencies. First, the orientation angle compensation is incorporated into the SMB filtering process to remedy the overestimation of the volume scattering contribution in the Freeman-Durden decomposition. In addition, an algorithm to select the homogenous pixels is developed based on the spatial majority rule for adaptive speckle reduction. We demonstrate the superiority of the proposed methods in terms of scattering property preservation and speckle noise reduction using L-band PolSAR data sets of San Francisco that were acquired by the NASA/JPL airborne SAR (AIRSAR) system.

The boiling heat transfer of evaporation cooling in a billet reheating furnace was simulated. The results indicate that the bubbles easily aggregate inside of the elbow and upper side of the horizontal regions in the π shaped support tubes. The circulation velocity increasing helps to improve the uniformity of vapor distribution and decrease the difference of vapor volume fraction between upper and down at end of the horizontal sections. With the increase of circulation velocity, the resistance loss and the circulation ratio both increase, but the former will decrease with the increase of work pressure.

The objective of this work is to model the microstructure of asphalt mixture and build virtual test for asphalt mixture by using Particle Flow Code in three dimensions (PFC^3D) based on three-dimensional discrete element method. A randomly generating algorithm was proposed to capture the three-dimensional irregular shape of coarse aggregate. And then, modeling algorithm and method for graded aggregates were built. Based on the combination of modeling of coarse aggregates, asphalt mastic and air voids, three-dimensional virtual sample of asphalt mixture was modeled by using PFC^3D. Virtual tests for penetration test of aggregate and uniaxial creep test of asphalt mixture were built and conducted by using PFC^3D. By comparison of the testing results between virtual tests and actual laboratory tests, the validity of the microstructure modeling and virtual test built in this study was verified. Additionally, compared with laboratory test, the virtual test is easier to conduct and has less variability. It is proved that microstructure modeling and virtual test based on three-dimensional discrete element method is a promising way to conduct research of asphalt mixture.

A model is proposed to describe the passengers’ route choice behaviors in urban railway traffic with stochastic link capacity degradation by considering two types of demand, sensitive and insensitive passenger. The insensitive passengers choose their route without paying much attention to congestion. To the contrary, sensitive passengers who consider route congestion choose travel route based on generalized cost. An equilibrium state is given by variational inequalities in terms of travel generalized cost, which is represented by the combinations of mean and variance of total travel time. The diagonalization algorithm is given to solve this programming. Results show that insensitive passengers have large effects on the path choice than sensitive ones, especially for the larger demand.