The high cycle fatigue response of a high V-alloyed powder metallurgy tool steel (AISI 11) with different inclusion sizes was studied. Two materials of this grade at a similar hardness of about HRC 60 were subjected to axial loading fatigue tests, tensile tests and fracture toughness measurements to investigate their mechanical properties. Large inclusion above 70 μm is indicated to be responsible for the tensile fracture which happens before yielding. The fatigue strength obtained up to 10⁷ cycles is found to decrease from approximately 1 538 MPa to 1000 MPa with the inclusion size increasing above 30 μm. The internally induced crack initiation is mainly attributed to the surface compressive residual stress of 300–450 MPa. Fractographic evaluation demonstrates that the crack initiation and propagation controlling factors of the two materials are almost the same, indicating that the two factors would be insignificantly affected by the inclusion size level. Paris sizes of the two materials both show a tendency to decrease as the ratio of stress intensity factor of crack origin to factor of fish-eye increases. The investigation into the relationship between stress intensity factors and fatigue life of the two materials further indicates that the high cycle fatigue behavior of AISI 11 is controlled by crack propagation.

The microstructure and surface state of three kinds of polyacrylonitrile-based carbon fibers (T700, T300 and M40) before and after high temperature treatment were investigated. Also, the pyrocarbon and thermal conductivity of carbon/carbon composites with different carbon fibers as preform were studied. The results show that M40 carbon fiber has the largest crystallite size and the least d₀₀₂, T300 follows, and T700 the third. With the increase of heat treatment temperature, the surface state and crystal size of carbon fibers change correspondingly. M40 carbon fiber exhibits the best graphitization property, followed by T300 and then T700. The different microstructure and surface state of different carbon fibers lead to the different microstructures of pyrocarbon and then result in the different thermal conductivities of carbon/carbon composites. The carbon/carbon composite with M40 as preform has the best microstructure in pyrocarbon and the highest thermal conductivity.

An Al-5.8Mg-0.4Mn-0.35(Sc+Zr) (mass fraction, %) alloy sheet was prepared using water chilling copper mould ingot metallurgy processing which was protected by active flux. The influence of stabilizing annealing on mechanical properties and microstructure of the cold rolling sheet was studied. The results show that the strength and hardness of the alloy decrease, while the elongation increases with increasing the stabilizing annealing temperature. With the increase of stabilizing annealing time, the strength and hardness of the alloy drop slightly but its ductility exhibits no change. Partial recovery and recrystallization orderly occur with the increase of annealing temperature during stabilizing treatment. Only different degrees of recovery occur in the alloys annealed below 400 °C for 1 h. Partial recrystallization occurs after annealed at 450 °C for 1 h. By annealing at 300 °C for 1 h, the alloy can obtain the optimum application values of σ_b, σ_0.2 and δ, which are 436 MPa, 327 MPa and 16.7%, respectively.

The synthesis, structure and performance of Li₂Mg_0.15Mn_0.4Co_0.45SiO₄/C cathode material were studied. The Li₂Mg_0.15Mn_0.4Co_0.45SiO₄/C solid solution with orthorhombic unit cell (space group Pmn2₁) was synthesized successfully by combination of wet process and solid-state reaction at high temperature, and its electrochemical performance was investigated primarily. Li₂Mg_0.15Mn_0.4Co_0.45SiO₄/C composite materials deliver a charge capacity of 302 mA·h/g and a discharge capacity of 171 mA·h/g in the first cycle. The discharge capacity is stabilized at about 100 mA·h/g after 10 cycles at a current density of 10 mA/g in the voltage of 1.5–4.8 V vs Li/Li⁺. The results show that Mg-substitution for the Co ions in Li₂Mn_0.4Co_0.6SiO₄ improves the stabilization of initial structure and the electrochemical performance.

First-principles calculations based on the density-functional theory were employed to study the crystal structure of vanadium phosphide compounds, such as V₃P, V₂P, VP, VP₂ and VP₄. Cohesive energy of five types of vanadium phosphide compounds was calculated to assess their structural stability. The charge density distribution and densities of states of vanadium phosphides were discussed to study further their electronic structures. The results show that the structure of metal-rich compounds is considerably more stable than the phosphorus-rich compositions, and covalent bond exists between the V and P atoms of V₃P, V₂P, VP, VP₂ and VP₄.

Organic matrices play an important role in biomineralization process. In order to explore the effect of both meso-tetrakis (4-hydroxylphenyl) porphyrin (THPP) and hydrogels on calcium carbonate mineralization, and consequently synthesize functional materials based on porphyrin and calcium carbonate with tunable shapes and optical properties, a new kind of biomimetic mineralization system which combined THPP with three biopolymer hydrogels (gelatin, agarose and calcium alginate gels) was designed and investigated. A carbonate diffusion method based on the generation of CO₂ by slow decomposition of ammonium hydrogen carbonate was adopted for calcium carbonate crystallization. The results show that both gelatin and alginate hydrogels exhibit the ability of stabilizing vaterite, while agarose only induces the formation of calcite. With participation of THPP in the mineralization environments, calcite is favored in all these hydrogels, while the crystal morphologies are greatly different from each other. These results indicate the perspective of THPP in regulating calcium carbonate crystallization and also provide a new strategy for fabricating advanced functional materials with controlled morphology and tunable optical properties based on calcium carbonate and THPP.

A two-step leaching method in combination of acid and ethylene diaminetetraacetic acid disodium (EDTA-Na₂) was applied to extract metals such as Cd, Cu, Fe, Pb and Zn from a zinc smelting slag. The results show that the extraction rates of Cd, Cu, Fe and Zn in slag reach 88.3%, 54.1%, 69.6% and 54.7%, respectively, while the extraction rate of Pb is only 0.05% leached with 1.25 mol/L sulfuric acid under the conditions of the ratio of slag to liquid of 100 g/L, 65 °C and 120 r/min for 2 h. However, Pb extraction rate from 1.25 mol/L sulfuric acid leached residue reaches as high as 66.5% by using 0.1 mol/L EDTA-Na₂ solution. The results indicate that two-step sequential extraction procedure combining 1.25 mol/L sulfuric acid and 0.1 mol/L EDTA-Na₂ solution can extensively extract Cd, Cu, Fe, Pb and Zn from zinc smelting slag.

Carbothermic reduction alumina in vacuum was conducted, and the products were analysed by means of XRD and gas chromatography. Thermodynamic analysis shows that in vacuum the initial carbothermic reduction reaction temperature reduces compared with that under normal pressure, and the preferential order of products is Al₄O₄C, Al₄C₃, Al₂OC, Al₂O and Al. Experiment results show that the carbothermic reduction products of alumina are Al₄O₄C and Al₄C₃, and neither Al₂OC, Al₂O or Al was found. During the carbothermic reduction process, the reaction rate of Al₂O₃ and carbon decreases gradually with increasing time. Meanwhile, lower system pressure or higher temperature is beneficial to the carbothermic reduction of alumina process. Al₄O₄C is firstly formed in the carbothermic reaction, and then Al₄C₃ is formed in lower system pressure or at higher temperature.

The chemical nature of the interaction of starch and dodecylamine (DDA), which generally act as depressant and collector, respectively, in the reverse flotation of bauxite, was investigated using starch-iodine tests. The results obtained from the blue-value measurements for starch+DDA+iodine system indicate the formation of the inclusion complex for amylose-DDA system at low DDA concentration (<2 mmol/L). However, it is less likely for amylopectin-DDA system with short helix. UV-Vis spectra of starch-iodine complexes show that each helix of amylose can accommodate two DDA molecules locating separately at its two ends, and in the helical cavity there is room available for the upcoming iodine. When concentrated DDA is tested, amylose-DDA system exhibits no characteristic starch-iodine color, owing to the presence of a compact coating of DDA molecules on starch via hydroxyl/amine hydrogen bonding. ¹H NMR spectroscopy and surface tension determination help to clarify the interaction mechanism of amylose with DDA.

Various control systems for a robotic excavator named LUCIE (Lancaster University Computerized and Intelligent Excavator), were investigated. The excavator is being developed to dig trenches autonomously. One stumbling block is the achievement of adequate, accurate, quick and smooth movement under automatic control. Here, both classical and modern approaches are considered, including proportional-integral-derivative (PID) control tuned by conventional Zigler-Nichols rules, linear proportional-integral-plus (PIP) control, and a novel nonlinear PIP controller based on a state-dependent parameter (SDP) model structure, in which the parameters are functionally dependent on other variables in the system. Implementation results for the excavator joint arms control demonstrate that SDP-PIP controller provides the improved performance with fast, smooth and accurate response in comparison with both PID and linearized PIP control.

In order to improve the screening efficiency of vibrating screen and make vibration process smooth, a new type of magnetorheological (MR) damper was proposed. The signals of displacement in the vibration process during the test were collected. The trispectrum model of autoregressive (AR) time series was built and the correlation dimension was used to quantify the fractal characteristics during the vibration process. The result shows that, in different working conditions, trispectrum slices are applied to obtaining the information of non-Gaussian, nonlinear amplitude-frequency characteristics of the signal. Besides, there is correlation between the correlation dimension of vibration signal and trispectrum slices, which is very important to select the optimum working parameters of the MR damper and vibrating screen. And in the experimental conditions, it is found that when the working current of MR damper is 2 A and the rotation speed of vibration motor is 800 r/min, the vibration screen reaches its maximum screening efficiency.

A semi-active magneto-rheological (MR) damper was experimentally investigated and compared to an original equipment manufacturer (OEM) damper for a passenger vehicle, by using a quarter car models. A full-scale two-degree-of-freedom quarter car experimental set-up was constructed to study the vehicle suspension. On-off skyhook controller and Fuzzy-Lyapunov skyhook controller (FLSC) were employed to control the input current for MR damper so as to achieve the desired damping force. Tests were done to evaluate the ability of MR damper for controlling vehicle vibration. Test results show that the semi-active MR vehicle suspension vibration control system is feasible. In comparison with OEM damper, on-off and FLSC controlled MR dampers can effectively reduce the acceleration of vehicle sprung mass by about 15% and 24%, respectively.

According to the cutting characteristics of progressive spiral movement by rotary cutting of the disc cutter, using the broken theory of interaction of compression and shearing, the three-axis force rotary cutting mechanical model of disc cutter was established and the influence of installation radius, the phase difference and the cutter space on the mechanics of disc cutter were analyzed. The results show that on the same radial line of tunneling interface, the boring distance of cutting tools installed on a different radius is not equal. The cutting radial line of tunneling interface is a polyline and its height is determined by phase angle and penetration of cutting tools. Both phase difference and the installation radius between adjacent disc cutters have little effect on the vertical force and rolling force, but increase with the increase in cutter spacing. In addition, when increasing phase difference and cutter space bilaterally, and reducing installation radius simultaneously, the lateral force would be improved. Related results have been verified on100 t rotary tool cutting test platform.

Bistable mechanisms are very appealing in the design of valves, switches and actuators. By utilizing the nonlinear magnetic structure and elastic cantilevers, a novel bistable mechanism was designed. Based on the magnetic charge model and material mechanics theory, the nonlinear force during the snap-through procedure was calculated accurately, which is in accordance with that obtained by the experiments. In addition, the bistable characteristics including the threshold snapping force, the traveling range, and stable positions can be adjusted by changing the structure parameters and the relative distance among the magnets. The dynamic analysis shows that the bistable structure has a good frequency distinguishing capacity for mechanical shock pulses.

Autonomous underwater vehicles (AUVs) navigating in complex sea conditions usually require a strong control system to keep the fastness and stability. The nonlinear trajectory tracking control system of a new AUV in complex sea conditions was presented. According to the theory of submarines, the six-DOF kinematic and dynamic models were decomposed into two mutually non-coupled vertical and horizontal plane subsystems. Then, different sliding mode control algorithms were used to study the trajectory tracking control. Because the yaw angle and yaw angle rate rather than the displacement of the new AUV can be measured directly on the horizontal plane, the sliding mode control algorithm combining cross track error method and line of sight method was used to fulfill its high-precision trajectory tracking control in the complex sea conditions. As the vertical displacement of the new AUV can be measured, in order to achieve the tracking of time-varying depth signal, a stable sliding mode controller was designed based on the single-input multi-state system, which took into account the characteristic of the hydroplane and the amplitude and rate constraints of the hydroplane angle. Moreover, the application of dynamic boundary layer can improve the robustness and control accuracy of the system. The computational results show that the designed sliding mode control systems of the horizontal and vertical planes can ensure the trajectory tracking performance and accuracy of the new AUV in complex sea conditions. The impacts of currents and waves on the sliding mode controller of the new AUV were analyzed qualitatively and quantitatively by comparing the trajectory tracking performance of the new AUV in different sea conditions, which provides an effective theoretical guidance and technical support for the control system design of the new AUV in real complex environment.

In order to obtain a new-type short cylindrical cup-shaped flexspline that can be applied to space mechanisms, the APDL language of ANSYS software was employed to develop a parameterized equivalent contact model between a flexspline and a wave generator. The validity of the parameterized equivalent contact model was verified by comparing the results of the analytic value of the contact model and the value calculated by the theoretical formula. The curvilinear trend of stress was obtained by changing the structural parameter of the flexspline. Based on the curvilinear trend of stress, multi-objective optimizations of key structural parameters were achieved. Flexspline, wave generator, and circular spline of a new 32-type short cylindrical cup-shaped harmonic reducer were designed and manufactured. A performance test bench to carry out tests on the harmonic reducer was designed. Contrast experiments were implemented to determine the efficiency of the new 32-type short cylindrical cup-shaped harmonic reducer and the conventional 32-type harmonic reducer under different conditions. The experimental results reveal that there is approximately equality in terms of efficiency between the new 32-type short cylindrical cup-shaped harmonic reducer and the conventional 32-type harmonic reducer. The volume of the flexspline of the new 32-type short cylindrical cup-shaped harmonic reducer is reduced by approximately 30% through multi-objective optimization. When the new 32-type short cylindrical cup-shaped harmonic reducer is used on the wheel of a rover prototype, the mass of the wheel hub is decreased by 0.42 kg. Test analysis of wheel motion verifies that the new 32-type short cylindrical cup-shaped harmonic reducer can meet the requirements regarding bearing capacity and efficiency.

In order to exactly provide scientific basis for pressure dynamic balance control of working chamber of earth pressure balance shield (EPBS), study on optimal arrangement of pressure measurement points in working chamber was conducted. Based on mathematical description of optimal arrangement for pressure measurement points, fuzzy clustering analysis and discriminant analysis were used to divide pressure regions of nodes on bulkhead. Finally, the selection method of optimal measurement points was proposed, and by selecting d6.28 m EPBS as study object, the case study was conducted. By contrast, based on optimal arrangement scheme of pressure measurement points, through adopting weighted algorithm, the absolute error mean of equivalent pressure of working chamber is the smallest. In addition, pressure curve of optimal arrangement points presents parabola, and it can show the state of pressure distribution on bulkhead truly. It is concluded that the optimal arrangement method of pressure measurement points in working chamber is effective and feasible, and the method can provide basis for realizing high precision pressure control of EPBS.

Solid oxide fuel cells (SOFCs) are considered to be one of the most important clean, distributed resources. However, SOFCs present a challenging control problem owing to their slow dynamics, nonlinearity and tight operating constraints. A novel data-driven nonlinear control strategy was proposed to solve the SOFC control problem by combining a virtual reference feedback tuning (VRFT) method and support vector machine. In order to fulfill the requirement for fuel utilization and control constraints, a dynamic constraints unit and an anti-windup scheme were adopted. In addition, a feedforward loop was designed to deal with the current disturbance. Detailed simulations demonstrate that the fast response of fuel flow for the current demand disturbance and zero steady error of the output voltage are both achieved. Meanwhile, fuel utilization is kept almost within the safe region.

A new approach for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems was proposed. This approach is based on assigning powers to the different subcarriers of OFDM using an unequal power distribution strategy. In addition, a reduced complexity selective mapping (RC-SLM) scheme was proposed. The proposed scheme is based on partitioning the frequency domain symbol sequence into several sub-blocks, and then each sub-block is multiplied by different phase sequences whose length is shorter than that used in the conventional SLM scheme. Then, a kind of low complexity conversions is used to replace the IFFT blocks. The performance of the proposed RC-SLM scheme along with the new approach was studied with computer simulation. The obtained results show that the proposed RC-SLM scheme is able to achieve the lowest computational complexity when compared with other low complexity schemes proposed in the literature while at the same time improves the PAPR reduction performance by about 0.3 dB.

A distributed local adaptive transmit power assignment (LA-TPA) strategy was proposed to construct a topology with better performance according to the environment and application scenario and prolong the network lifetime. It takes the path loss exponent and the energy control coefficient into consideration with the aim to accentuate the minimum covering district of each node more accurately and precisely according to various network application scenarios. Besides, a self-healing scheme that enhances the robustness of the network was provided. It makes the topology tolerate more dead nodes than existing algorithms. Simulation was done under OMNeT++ platform and the results show that the LA-TPA strategy is more effective in constructing a well-performance network topology based on various application scenarios and can prolong the network lifetime significantly.

Content extraction of HTML pages is the basis of the web page clustering and information retrieval, so it is necessary to eliminate cluttered information and very important to extract content of pages accurately. A novel and accurate solution for extracting content of HTML pages was proposed. First of all, the HTML page is parsed into DOM object and the IDs of all leaf nodes are generated. Secondly, the score of each leaf node is calculated and the score is adjusted according to the relationship with neighbors. Finally, the information blocks are found according to the definition, and a universal classification algorithm is used to identify the content blocks. The experimental results show that the algorithm can extract content effectively and accurately, and the recall rate and precision are 96.5% and 93.8%, respectively.

A 3D temperature field distribution of biological tissue for superficial hyperthermia using a pulse modulated microwave (PMMW) was presented. A 3D sliced homogeneous phantom was radiated by the PMMW and an infrared thermal imager was applied to image temperature distribution throughout the phantom. The period of the PMMW is 3 s and the output power is 35 W. The temperature rises by at least 3 °C in the phantom when the duty cycle varies from 1/3, 1/2, 2/3 to 1 (denoted by scenarios 1–4). Both the accumulative temperature-volume histogram and the relative depth-area ratio histogram show that the maximum temperature rise (MTR) is 6.6 and 8 °C in scenarios 2 and 3, and they are superior to scenarios 1 and 4. Furthermore, the PMMW can control temperature field distribution of biological tissue. It provides both preliminary basis for thermal volume control and new technology for temperature control and monitor in superficial hyperthermia.

Based on the energy equation of gas-liquid flow in pipeline, the explicit temperature drop formula for gas-liquid steady state calculation was derived. This formula took into consideration the Joule-Thomson effect, impact of terrain undulation and heat transfer with the surroundings along the line. Elimination of temperature iteration loop and integration of the explicit temperature equation, instead of enthalpy energy equation, into the conjugated hydraulic and thermal computation have been found to improve the efficiency of algorithm. Then, the inner wall temperature of gas-liquid flow was calculated by using explicit temperature equation and inner wall convective heat transfer coefficient of mixed flow which can be obtained by liquid convective heat transfer coefficient and gas convective heat transfer coefficient on the basis of liquid holdup. The temperature results of gas-liquid flow and inner wall in the case example presented both agree well with those in professional multiphase computational software OLGA.

An experimental model of maldistribution was established and grey correlation analysis method was employed to describe quantitatively the maldistribution phenomenon in the feeding device of copper flash smelting. Particle motion in the feeding device was separated into uniform flow in chute and restricted slanting parabolic motion in distributor channel. Factors affecting particle velocity at the chute outlet and particle moving distance in the distributor channel, which also cause the maldistribution, were analyzed based on the assumption of pseudo fluid. Experiments were conducted to study the maldistribution using river sand. The results indicate obvious mass maldistribution and an even higher degree with the increase of feeding mass rate; meanwhile, size maldistribution is negligible. Also, feeding intensity has a larger impact on circumferential maldistribution than on radial maldistribution. Based on the experimental results of the eight factors impacting the maldistribution, grey relation of each factor was calculated using grey correlation analysis. The importances of these factors were sequenced. The results show that a proper adjustment of the structure will ameliorate the maldistribution phenomenon in the feeding device of copper flash smelting.

The electrochemical treatment of wastewater containing chlorophenols (2-monochlorophenol, 4-monochlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol) was carried out experimentally with synthetic boron-doped diamond (BDD) thin film electrodes. Current vs time curves under different cell voltages were measured. Removal rate of COD, instant current efficiency (ICE) and energy consumption were investigated under different current densities. The influence of supporting media is reported, which plays an important role in determining the global oxidation rate. The oxidative chloride is stronger than peroxodisulphate. The electrochemical characteristics of boron-doped diamond electrodes were investigated in comparison with active coating Ti substrate anode (ACT). The experimental results show that BDD is markedly superior to ACT due to its different absorption properties.

Due to the complex features of rock mass blastability assessment systems, an evaluation model of rock mass blastability was established on the basis of the unascertained measurement (UM) theory and the actual characteristics of the project. Considering a comprehensive range of intact rock properties and discontinuous structures of rock mass, twelve main factors influencing the evaluation blastability of rock mass were taken into account in the UM model, and the blastability evaluation index system of rock mass was constructed. The unascertained evaluation indices corresponding to the selected factors for the actual situation were solved both qualitatively and quantitatively. Then, the UM function of each evaluation index was obtained based on the initial data for the analysis of the blastability of six rock mass at a highway improvement cutting site in North Wales. The index weights of the factors were calculated by entropy theory, and credible degree identification (CDI) criteria were established according to the UM theory. The results of rock mass blastability evaluation were obtained by the CDI criteria. The results show that the UM model assessment results agree well with the actual records, and are consistent with those of the fuzzy sets evaluation method. Meanwhile, the unascertained superiority degree of rock mass blastability of samples S1–S6 which can be calculated by scoring criteria are 3.428 5, 3.453 3, 4.058 7, 3.675 9, 3.516 7 and 3.289 7, respectively. Furthermore, the proposed method can take into account large amount of uncertain information in blastability evaluation, which can provide an effective, credible and feasible way for estimating the blastability of rock mass. Engineering practices show that it can complete the blastability assessment systematically and scientifically without any assumption by the proposed model, which can be applied to practical engineering.

Sulfur speciation transformation during bioleaching of pyrite-containing sphalerite concentrate by thermophile Sulfolobus metallicus (S. metallicus) at 65 °C was investigated by X-ray diffraction (XRD), diffuse reflectance Fourier transform infrared spectroscopy (FT-IR) and sulfur K-edge X-ray absorption near edge structure spectroscopy (XANES). The results show that the presence of S. metallicus effectively enhances the dissolution of the mineral. The yield of zinc increases from 0.5 g/L in sterile control to 2.7 g/L in bioleaching. The pyrite in the concentrate facilitates zinc dissolution in the early stage, but has hindrance role in the late stage for the formation of jarosite. Sulfur speciation analyses show that jarosite and elemental sulfur are main products in bioleaching process, and the accumulation of jarosite is mainly responsible for the decline of leaching efficiency.

Modified humic acid (MHA) binder based on lignite humic substances is a novel sort of promising organic binder for iron ore pellets. Humic acid (HA) is one of the main ingredients of MHA binder. Pure HA was firstly isolated from lignite and then adsorption of HA onto magnetite particle surface was investigated. The final results indicate that the adsorption of HA onto magnetite surface accords with Langmuir model well, and it is evidently influenced by the initial HA concentration and solution pH value. Adsorption depends on chemical interaction at pH values above the PZC (the pH where the Zeta potentials of minerals are zero) of magnetite, while electrostatic attraction and chemical interaction both contribute to the adsorption at pH values below the PZC.

Bioleaching is an environment-friendly and economical technique to remove heavy metals from contaminated soil. The objective of this work is to find out an indigenous strain to remedy soil contaminated by Zn, Pb, Cu and Cd. A strain which was selected from the soil of a local smelting industry was found to be able to produce many organic acids and degrade pH value of the liquid medium. The fungus strain is identified as Penicillium Chrysogenum (P. Chrysogenum) by sequencing 18srDNA and ITS. Bioleaching condition using P. Chrysogenum is optimized. Glucose is the best carbon source for P. Chrysogenum and inorganic nitrogen is better than organic nitrogen. In addition, neutral solution and room temperature are fit for P. Chrysogenum to bioleach. In the one-step bioleaching, the bioleaching ratios are 39.95% for Zn, 9.4% for Pb, 34.89% for Cu and 49.59% for Cd, which are 53.89% for Zn, 14.44% for Pb, 55.53% for Cu and 62.81% for Cd in the two-step bioleaching. The efficiency of two-step bioleaching is better than the one-step bioleaching. P. Chrysogenum is effective in removing heavy metals from the contaminated soil.

A nonlinear flow reservoir mathematical model was established based on the flow characteristic of low-permeability reservoir. The well-grid equations were deduced and the dimensionless permeability coefficient was introduced to describe the permeability variation of nonlinear flow. The nonlinear flow numerical simulation program was compiled based on black-oil model. A quarter of five-spot well unit was simulated to study the effect of nonlinear flow on the exploitation of low-permeability reservoir. The comprehensive comparison and analysis of the simulation results of Darcy flow, quasi-linear flow and nonlinear flow were provided. The dimensionless permeability coefficient distribution was gained to describe the nonlinear flow degree. The result shows that compared with the results of Darcy flow, when considering nonlinear flow, the oil production is low, and production decline is rapid. The fluid flow in reservoir consumes more driving energy, which reduces the water flooding efficiency. Darcy flow model overstates the reservoir flow capability, and quasi-linear flow model overstates the reservoir flow resistance. The flow ability of the formation near the well and artificial fracture is strong while the flow ability of the formation far away from the main streamline is weak. The nonlinear flow area is much larger than that of quasi-linear flow during the fluid flow in low-permeability reservoir. The water propelling speed of nonlinear flow is greatly slower than that of Darcy flow in the vertical direction of artificial fracture, and the nonlinear flow should be taken into account in the well pattern arrangement of low-permeability reservoir.

The mechanical behaviors of the interface between coarse-grained soil and concrete were investigated by simple shear tests under condition of mixed soil slurry (bentonite mixed with cement grout). For comparison, the interfaces both without slurry and with bentonite slurry were analyzed. The experimental results show that different slurries exert much influence on the strength and deformation of soil/structure interface. Under mixed soil slurry, strain softening and shear dilatation are observed, while shear dilatation appears under the small normal stress of the interface without slurry, and shear contraction is significant under the condition of the bentonite slurry. The thickness of the interface was determined by analyzing the disturbed height of the sample with both simple shear test and particle flow code (PFC). An elasto-plastic constitutive model incorporating strain softening and dilatancy for thin layer element of interface was formulated in the framework of generalized potential theory. The relation curves of shear stress and shear strain, as well as the relation curves of normal strain and shear strain, were fitted by a piecewise function composed by hyperbolic functions and resembling normal functions. The entire model parameters can be identified by tests. The new model is verified by comparing the measured data of indoor cut-off wall model tests with the predictions from finite element method (FEM). The FEM results indicate that the stress of wall calculated by using Goodman element is too large, and the maximum deviation between the test data and prediction is about 45%. While the prediction from the proposed model is close to the measured data, and the error is generally less than 10%.

Taking the effect of finite soil layers below pile end into account, the longitudinal dynamic response of pile undergoing dynamic loading in layered soil was theoretically investigated. Firstly, finite soil layers below pile end are modeled as virtual soil pile whose cross-section area is the same as that of the pile and the soil layers surrounding the pile are described by the plane strain model. Then, by virtue of Laplace transform and impedance function transfer method, the analytical solution of longitudinal dynamic response at the pile head in frequency domain is yielded. Also, the semi-analytical solution in time domain undergoing half-cycle sine pulse at the pile head is obtained by means of inverse Laplace transform. Based on these solutions, a parametric study is conducted to analyze emphatically the effects of parameters of soil below pile end on velocity admittance and reflected wave signals at the pile head. Additionally, a comparison with other models with different supporting conditions from soil below pile end is performed to verify the model presented.

Based on the upper bound theorem of limit analysis, the factor of safety for shallow tunnel in saturated soil is calculated in conjunction with the strength reduction technique. To analyze the influence of the pore pressure on the factor of safety for shallow tunnel, the power of pore pressure is regarded as a power of external force in the energy calculation. Using the rigid multiple-block failure mechanism, the objective function for the factor of safety is constructed and the optimal solutions are derived by employing the sequential quadratic programming. According to the results of optimization calculation, the factor of safety of shallow tunnel for different pore pressure coefficients and variational groundwater tables are obtained. The parameter analysis shows that the pore pressure coefficient and the location of the groundwater table have significant influence on the factor of safety for shallow tunnel.

The seepage under a dam foundation is mainly controlled by the performance of the curtain. Its anti-seepage behavior may be weakened by the long term physic-chemical actions from groundwater. According to seepage hydraulics and geochemistry theory, a coupling model for assessing the behavior of the curtain under a dam foundation is set up, which consists of seepage module, solute transport module, geochemistry module and curtain erosion module, solved by FEM. A case study was carried out. The result shows that the curtain efficiency is weakened all the time. Aqueous calcium from the curtain is always in dissolution during the stress period for simulation, which leads to the increasing amount in groundwater reaching 846.35–865.312 g/m³. Within the domain, reaction extent differs in different parts of the curtain. The dissolution of Ca(OH)₂ accounts to 877.884 g/m³ near the bottom and is much higher than that of the other parts. The erosion is much more serious near the bottom of the curtain than the other parts, which is the same to the upstream and downstream. Calcium dissolution is mainly controlled by hydraulic condition and dispersion, and it varies in a non-linear way within the domain.

To disclose the grain crushing effects on the weathered granular soil rheological behavior, a series of rheological tests (odometer compression and triaxial shearing) were carried out. At the same time, the sieving analysis tests of these specimens were also executed before and after tests, and the grain crushing degree, B_r and n₅, were collectively adopted to estimate the grain crushing. The grain crushing degree depends on the stress path, stress level, and load time, especially, the longer load time and more intensive gradient shearing path will increase the grain crushing quantity. The Hardin crushing degrees B_r are 0.191, 0.118 and 0.085 in the ordinary compression, rheological compression and triaxial rheological shearing, respectively; The grain crushing degrees n₅ are 1.9, 1.4 and 1.32, respectively. The strain softening phase indicates the grain crushing and diffusive collapse, and the strain hardening phase indicates the rearrangement of these crushed grains and formation of new bearing soil skeleton. The rheological deformation of granular soil can be attributed to the coarse grain crushing and the filling external porosity with crushed fragments.

Cliff deformation behavior after conservation is of great significance for evaluating the conservation effect and discovering the dynamical law of soil. Modeling on deformation behavior is beneficial to the quantitative evaluation of interactions between soil mass and structures as well as the forecast. Based on cliff conservation engineering of Jiaohe Ruins (the largest raw soil heritage site in the world), data of horizontal deformation of the upper cliff were obtained by using Nanrui-made NDW-50 displacement device (precision: 0.01 mm, frequency: 15 min⁻¹). Regression analysis indicates that deformation behavior models include exponential growth, linear growth and parabolic growth types, while daily deformation presents more intense periodicity (24 h). The deformation is less than 1.5 mm during monitoring period, which has no impact on the stability of cliff. Deformation behavior provides the mutual duress and interaction between soil and engineering intervention. In addition, deformation mode attaches tensely to the damage pattern of the cliff. The conclusions are of importance to the stability evaluation of the carrier along Silk Road.

A field study on the behavior of three destructive piles in soft soils subjected to axial load was presented. All the three piles with different diameters were base-grouted and installed with strain gauges along the piles. The complete load transfer behavior of the base-grouted pile was analyzed using measured results. Moreover, the thresholds of the relative pile-soil displacement for fully mobilizing skin frictions in different soils were investigated, and pile tip displacements needed to fully mobilize tip resistances were analyzed. The results of the full-scale loading tests show that the skin frictions are close to the ultimate values when the pile-soil relative displacements are 1%–3% of pile diameter, and the pile tip displacements needed to fully mobilize the tip resistances are about 1.3%–2.0% of pile diameter. The load transmission curve of the soils around the pile tip corresponds to a softening model when the pile is loaded to failure.

Based on dynamic triaxial test results of saturated soft clay, similarities of variations between accumulated pore water pressure and accumulated deformation were analyzed. The Parr’s equation on accumulated deformation was modified to create an attenuation-type curve model on accumulated pore water pressure in saturated normal consolidation clay. In this model, dynamic strength was introduced and a new parameter called equivalent dynamic stress level was added. Besides, based on comparative analysis on variations between failure-type and attenuation-type curves, a failure-type curve model was created on accumulated pore water pressure in saturated normal consolidation clay. Two models can take cycle number, coupling of static and dynamic deviator stress, and consolidation way into consideration. The models are verified by test results. The correlation coefficients are more than 0.98 for optimization of test results based on the two models, and there is good agreement between the optimized and test curves, which shows that the two models are suitable to predict variations of accumulated pore water pressure under different loading cases and consolidation ways. In order to improve prediction accuracy, it is suggested that loading cases and consolidation ways should be consistent with in-situ conditions when dynamic triaxial tests are used to determine the constants in the models.

Experimental research was conducted to study the structural behaviors of a steel roof truss model without fire-proof coating under pool fire conditions. The data of temperature distribution and displacements of typical members were obtained. It is found that the temperature distribution of environment inside the structure, which is found to be in accordance with the multi-zone model with height, has a decisive effect on the temperature evolution of steel members. Besides, it can also be observed that due to the restriction and coordination among the truss members in the localized fire, the maximum relative deflection, which occurs at the mid-span of the top chord, is relatively slight and has not exceeded 1 mm under experimental conditions. On the other hand, the column experiences a notable thermal expansion during the test. Then, a finite element model is presented and validated by the test results.

Based on 3D, steady N-S equations and k-ɛ turbulence model, Fluent was employed to do numerical simulation for lateral aerodynamic performance of 6-axis X2K double-deck container trains with two different loading forms, and speed limits of the freight trains were studied. The result indicates that under wind environment: 1) As for vehicles without and with cross-loaded structure, aero-pressure on the former is bigger, but air velocity around the latter is larger; 2) When sideslip angle θ=0°, the airflow is symmetry about train vertical axis; when θ>0°, the airflow is detached at the top of vehicles, and the air velocity increases above the separated line but decreases below it; 3) With θ increasing, the lateral force on the mid vehicle firstly increases but decreases as θ=75°; 4) When the 6-axis X2K flat car loads empty boxes of a 40 ft and a 48 ft at 120 km/h, the overturning wind speed is 25.19 m/s, and the train should be stopped under the 12th grade wind speed.

Handover location technology was employed for collecting road traffic information in a number of field projects, and the project results demonstrate that it is a supplementary and promising means of road traffic information collection for further traffic supervision and maintenance. Because handover location technology is one kind of pattern matching based location technologies, offline handover location positioning is an essential problem to be studied for successfully matching mobile probes on GIS map. Offline handover location positioning method involves two stages, handover location positioning respectively via two weighted models and an optimized model based on the intermediate results obtained in the first stage. A preliminary field test is conducted on a stretch of freeway in the inner suburban region in Beijing, and performance evaluation results show that the proposed method is superior to standard least square model in location accuracy and location precision, which is an effective method of offline handover location positioning.