The anoxic decomposition and influence of carbon precursors on the properties of LiFePO₄/C prepared by using Fe₂O₃ were investigated. X-ray powder diffractometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and carbon content and charge–discharge tests were applied to the characterization of the as-synthesized cathodes. Partial carbon is lost in the anaerobic decomposition of organic precursors and a high hydrogen content leads to a high residual carbon rate. Pyromellitic anhydride and citric acid participate in reactions before and in ball-milling. All the chosen carbon precursors are capable of producing LiFePO₄ with high degree of crystallinity and purity. The carbon derived from α-D-glucose, pyromellitic anhydride, soluble starch, citric acid and polyacrylamide has a loose and porous texture in LiFePO₄/C which forms conduction on and between LiFePO₄ particles. LiFePO₄/C prepared by using α-D-glucose, pyromellitic anhydride, citric acid and sucrose exhibits appreciable electrochemical performance. Graphite alone is able to enhance the electrochemical performance of LiFePO₄ to a limited extent but incapable of preparing practical cathode.

Surface microstructure and mechanical properties of pearlitic Fe–0.8%C (mass fraction) steel after laser shock processing (LSP) with different laser pulse energies were investigated by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD) and microhardness measurements. After LSP, the cementite lamellae were bent, kinked and broken into particles. Fragmentation and dissolution of the cementite lamellae were enhanced by increasing the laser pulse energy. Due to the dissolution of carbon atoms in the ferritic matrix, the lattice parameter of α-Fe increased. The grain size of the surface ferrite was refined, and the microstructure changed from lamellae to ultrafine micro-duplex structure (ferrite (α)+cementite (θ)) with higher laser pulse energy, accompanied by the residual stress and microhardness increase.

Aluminum foam is widely used in diverse areas to minimize the weight and maximize the absorption of shock energy in lightweight structures and various bio-materials. It presents a number of advantages, such as low density, incombustibility, non-rigidity, excellent energy absorptivity, sound absorptivity and low heat conductivity. The aluminum foam with an air cell structure was placed under the TDCB Mode II tensile load by using Landmark equipment manufactured by MTS to examine the shear failure behavior. The angle of the tapered adhesively-bonded surfaces of specimens was designated as a variable, and three models were developed with the inclined angles differing from one another at 6°, 8° and 10°. The specimens with the inclined angles of 6°, 8° and 10° have the maximum reaction forces of 168 N, 194 N when the forced displacements are 6, 5 and 4.2 mm respectively. There are three specimens with the inclined angles of 10°, 8° and 6° in the order of maximum reaction force. As the analysis result, the maximum equivalent stresses of 0.813 MPa and 0.895 MPa happened when the forced displacements of 6 mm and 5 mm proceeded at the models of 6° and 8°, respectively. A simulation was carried out on the basis of finite element method and the experimental design. The results of the experiment and the simulation analysis are shown not different from each other significantly. Thus, only a simulation could be confirmed to be performed in substitution of an experiment, which is costly and time-consuming in order to determine the shearing properties of materials made of aluminum foam with artificial data.

Simulated heap bioleaching of low-grade high pyrite-bearing chalcocite ore was conducted at 40°C with aeration of CO₂ and N₂. Ore samples were collected at day 43, 64, 85, 106 and subjected to microbial community analysis by 16S rRNA gene clone library. Phylogenetic analyses of 16S rDNA fragments revealed that the retrieved sequences are mainly related to genus Acidithiobacillus, Leptospirillum and Sulfobacillus. Aeration of CO₂ and N₂ significantly impacted the microbial community composition. When CO₂ was aerated, the proportion of genus Acidithiobacillus considerably increased, whereas the proportion of genus Leptospirillum and genus Sulfobacillus declined. However, with the aeration of N₂, the proportion of genus Acidithiobacillus and Leptospirillum increased, but genus Sulfobacillus decreased. When there was no aeration, the microbial community was similar to the inocula with the proportion of genus Leptospirillum mounted. These results indicated that the limitation of oxygen could change the bioleaching microbial community and the aeration of CO₂ and N₂ was favourable for the growth of sulfur-oxidizer (At. caldus) and iron-oxidizer (L. ferriphilum) respectively, which could be used for the regulation of microorganisms’ role in mineral bioleaching.

The application of microwave irradiation for pretreatment of copper anode slime with high nickel content prior to pressure sulfuric acid leaching has been proposed. The microwave-assisted pretreatment is a rapid and efficient process. Through the technology of microwave assisted pretreatment-pressure leaching of copper anode slime, copper, tellurium, selenium and nickel are almost completely recovered. Under optimal conditions, the leaching efficiencies of copper, tellurium, selenium and nickel are 97.12%, 95.97%, 95.37% and 93.90%, respectively. The effect of microwave radiation on the temperature of copper anode slime and leaching solution is investigated. It is suggested that the enhancement on the recoveries of copper, tellurium and selenium can be attributed to the temperature gradient which is caused by shallow microwave penetration depth and super heating occurring at the solid-liquid interface. The kinetic study shows that the pressure leaching of copper anode slime, with and without microwave assisted pretreatment, are both controlled by chemical reactions on the surfaces of particles. It is found that the activation energy calculated for microwave-assisted pretreatment-pressure leaching (49.47 kJ/mol) is lower than that for pressure leaching which is without microwave assisted pretreatment (60.57 kJ/mol).

A hydrometallurgical process was developed for recycling pharmaceutical blisters. Leaching aluminum from pharmaceutical blisters using sodium hydroxide (NaOH) solutions was investigated with respect to leaching behaviors and kinetics. A L₉ (3⁴) orthogonal design of experiments suggests that the most significant factor is NaOH concentration followed by temperature and leaching time. Factorial experiments demonstrate that the leaching rate of aluminum increases with increasing of the factors. The optimum conditions are temperature of 70 °C, leaching time of 20 min, NaOH concentration of 1.25 mol/L, liquid-to-solid mass ratio of 15:1 and agitation speed of 400 r/min. Under optimum conditions, the leaching rate is up to 100%, implying that aluminum and polyvinyl chloride (PVC) plastic in pharmaceutical blisters are separated completely. Kinetics of leaching aluminum is best described by the product layer diffusion control model, and the activation energy is calculated to be 19.26 kJ/mol.

CdS quantum dots sensitized platelike WO₃ photoelectrodes were successfully synthesized by a facile hydrothermal method and a modified chemical bath deposition (CBD) technique. To further improve the stability of the photoelectrodes in alkaline environment, the platelike WO₃ films were treated with TiCl₄ to form a nano-TiO₂ buffer layer on the WO₃ plate surface before loading CdS QDs. The resulting electrodes were characterized by using XRD, SEM, HR-TEM and UV-vis spectrum. The photocatalytic activity of the resulting electrodes was investigated by degradation of methyl orange (MO) in aqueous solution. The photoelectrochemical (PEC) property of the resulting electrodes was also characterized by the linear sweep voltammetry. The results of both the degradation of MO and photocurrent tests indicated that the as-prepared CdS QDs sensitized WO₃ platelike photoelectrodes exhibit a significant improvement in photocatalytic degradation and PEC activity under visible light irradiation, compared with unsupported CdS QDs electrodes. Significantly, coating the WO₃ plates with nano-TiO₂ obviously facilitate the charge separation and retards the charge-pair recombination, and results in a highest activity for QDs CdS/TiO₂/WO₃ photoelectrodes.

Suspension roasting followed by magnetic separation is a promising method to upgrade oolitic hematite ore. An oolitic hematite ore was roasted using suspension roasting technology at different temperatures. The phase transformation for iron minerals was investigated by XRD and Mossbauer spectrum, and the characteristics of roasted product were analyzed by VSM and SEM-EDS. Results indicate that the magnetic concentrate is of 58.73% Fe with iron recovery of 83.96% at 650 °C. The hematite is rapidly transformed into magnetite during the roasting with transformation ratio of 92.75% at 650 °C. Roasting temperature has a significant influence on the phase transformation of hematite to magnetite. The transformation ratio increases with increased temperature. After roasting, the magnetic susceptibility is significantly improved, while iron ore microstructure is not altered significantly.

In order to restore force sensation to robot-assisted minimally invasive surgery (RMIS), design and performance evaluation of a miniature 6-axis force/torque sensor for force feedback is presented. Based on the resistive sensing method, a flexural-hinged Stewart platform is designed as the flexible structure, and a straightforward optimization method considering the force and sensitivity isotropy of the sensor is proposed to determine geometric parameters which are best suited for the given external loads. The accuracy of this method is preliminarily discussed by finite element methods (FEMs). The sensor prototype is fabricated with the development of the electronic system. Calibration and dynamic loading tests for this sensor prototype are carried out. The working ranges of this sensor prototype are 30 N and 300 N·mm, and resolutions are 0.08 N in radial directions, 0.25 N in axial direction, and 2.4 N·mm in rotational directions. It also exhibits a good capability for a typical dynamic force sensing at a frequency close to the normal heart rate of an adult. The sensor is compatible with surgical instruments for force feedback in RMIS.

Wave driven unmanned surface vehicle (WUSV) is a new concept ocean robot drived by wave energy and solar energy, and it is very suitable for the vast ocean observations with incomparable endurance. Its dynamic modeling is very important because it is the theoretical foundation for further study in the WUSV motion control and efficiency analysis. In this work, the multibody system of WUSV was described based on D-H approach. Then, the driving principle was analyzed and the dynamic model of WUSV in longitudinal profile is established by Lagrangian mechanics. Finally, the motion simulation of WUSV and comparative analysis are completed by setting different inputs of sea state. Simulation results show that the WUSV dynamic model can correctly reflect the WUSV longitudinal motion process, and the results are consistent with the wave theory.

A novel air-powered twin-rotor piston engine (ATPE) utilizing a differential velocity driving mechanism to achieve a high output torque was proposed. The ATPE had eight separated rotary cylinders which can dynamically enlarge the engine displacement as a result of the special driving mechanism, which was named dynamic volume expansion. The mathematical model of ATPE comprising a dynamic model and a thermodynamic model was established under the assumption of no mechanical friction. The model was numerically simulated in Matlab. The results show that shortage of low output torque confusing traditional air-powered engines can be overcome. The average output torque sharply increases to 100 N·m, which is about three times that of traditional air-powered engines with equal cylinder displacement under the pressure of 0.6 MPa at 480 r/min. ATPE can be used to drive vehicles directly without transmission box, therefore the energy transfer efficiency of ATPE can be increased. Furthermore, benefitting from the novel gas distribution system, the engine shows an ability in self-adjusting under different loads. The arrangements of air ports automatically adjust the open interval of air ports according to the load, which may simplify the speed control system.

A complete mathematical model for logarithmic spiral type sprag one-way clutch design and analysis is given. It assumes that the motion of all clutch components can be expressed by a model of epicyclic gearing. It takes advantage of Hunt-Crossley contact impact theory to calculate the contact forces between sprags and races, and it can be used for optimization of design and comparison with other types of sprag clutches. A good deal of analysis shows that the parameters of the steady windup angle, the steady contact force, the natural frequency and natural cycle of clutch have nothing to do with the initial velocity of outer race, while the parameters of the maximum transient windup angle, the maximum transient impact force and the steady engagement time increase linearly in the mode of engaging operation of clutch. It is also shown that the strut angle has great influence on the dynamic engagement performance of clutch. The parameters of the steady windup angle, the maximum transient windup angle, the steady engaging time, the steady contact force, the maximum transient impact force and the natural cycle of clutch decrease linearly nearly with the inner strut angle, while the natural frequency of the system increases linearly with the inner strut angle.

Leveler is widely used to improve the quality of defective mild steel plates. Its typical ranges of the leveling capacity are constrained by three criteria, namely the maximum stroke of rollers, allowable total leveling force and motor power. In this work, an optimization model with equality and inequality constraints was built for the maximum yield stress search of each thickness of plates. The corresponding search procedure with three loops was given. The approximate range by the simplification model could be used as the initial value for the actual range search of the leveling capacity. Therefore, the search speed could be accelerated compared with a global search. The consistency of the analytical results and field data demonstrates the reliability of the proposed model and procedure. The typical ranges of the leveling capacity are expressed by several boundary curves which are helpful to judge whether the incoming plate can be leveled quickly or not. Also, these curves can be used to find the maximum yield stress for a specific thickness or the maximum thickness for a yield stress for plates.

For the position tracking control of hydraulic manipulators, a novel method of time delay control (TDC) with continuous nonsingular terminal sliding mode (CNTSM) was proposed in this work. Complex dynamics of the hydraulic manipulator is approximately canceled by time delay estimation (TDE), which means the proposed method is model-free and no prior knowledge of the dynamics is required. Moreover, the CNTSM term with a fast-TSM-type reaching law ensures fast convergence and high-precision tracking control performance under heavy lumped uncertainties. Despite its considerable robustness against lumped uncertainties, the proposed control scheme is continuous and chattering-free and no pressure sensors are required in practical applications. Theoretical analysis and experimental results show that faster and higher-precision position tracking performance is achieved compared with the traditional CNTSM-based TDC method using boundary layers.

As the central component of rotating machine, the performance reliability assessment and remaining useful lifetime prediction of bearing are of crucial importance in condition-based maintenance to reduce the maintenance cost and improve the reliability. A prognostic algorithm to assess the reliability and forecast the remaining useful lifetime (RUL) of bearings was proposed, consisting of three phases. Online vibration and temperature signals of bearings in normal state were measured during the manufacturing process and the most useful time-dependent features of vibration signals were extracted based on correlation analysis (feature selection step). Time series analysis based on neural network, as an identification model, was used to predict the features of bearing vibration signals at any horizons (feature prediction step). Furthermore, according to the features, degradation factor was defined. The proportional hazard model was generated to estimate the survival function and forecast the RUL of the bearing (RUL prediction step). The positive results show that the plausibility and effectiveness of the proposed approach can facilitate bearing reliability estimation and RUL prediction.

The noise of closed loop micro-electromechanical systems (MEMS) capacitive accelerometer is treated as one of the significant performance specifications. Traditional optimization of noise performance often focuses on designing large capacitive sensitivity accelerometer and applying closed loop structure to shape total noise, but different noise sources in closed loop and their behaviors at low frequencies are seldom carefully studied, especially their behaviors with different electronic parameters. In this work, a thorough noise analysis is established focusing on the four noise sources transfer functions near 0 Hz with simplified electronic parameters in closed loop, and it is found that the total electronic noise equivalent acceleration varies differently at different frequency points, such that the noise spectrum shape at low frequencies can be altered from 1/f noise-like shape to flat spectrum shape. The bias instability changes as a consequence. With appropriate parameters settings, the 670 Hz resonant frequency accelerometer can reach resolution of

Improving vehicle fuel consumption, performance and aerodynamic efficiency by drag reduction especially in heavy vehicles is one of the indispensable issues of automotive industry. In this work, the effects of adding append devices like deflector and cab vane corner on heavy commercial vehicle drag reduction were investigated. For this purpose, the vehicle body structure was modeled with various supplementary parts at the first stage. Then, computational fluid dynamic (CFD) analysis was utilized for each case to enhance the optimal aerodynamic structure at different longitudinal speeds for heavy commercial vehicles. The results show that the most effective supplementary part is deflector, and by adding this part, the drag coefficient is decreased considerably at an optimum angle. By adding two cab vane corners at both frontal edges of cab, a significant drag reduction is noticed. Back vanes and base flaps are simple plates which can be added at the top and side end of container and at the bottom with specific angle respectively to direct the flow and prevent the turbulence. Through the analysis of airflow and pressure distribution, the results reveal that the cab vane reduces fuel consumption and drag coefficient by up to 20 % receptively using proper deflector angle. Finally, by adding all supplementary parts at their optimized positions, 41% drag reduction is obtained compared to the simple model.

The control of gas fractionation unit (GFU) in petroleum industry is very difficult due to multivariable characteristics and a large time delay. PID controllers are still applied in most industry processes. However, the traditional PID control has been proven not sufficient and capable for this particular petro-chemical process. In this work, an incremental multivariable predictive functional control (IMPFC) algorithm was proposed with less online computation, great precision and fast response. An incremental transfer function matrix model was set up through the step-response data, and predictive outputs were deduced with the theory of single-value optimization. The results show that the method can optimize the incremental control variable and reject the constraint of the incremental control variable with the positional predictive functional control algorithm, and thereby making the control variable smoother. The predictive output error and future set-point were approximated by a polynomial, which can overcome the problem under the model mismatch and make the predictive outputs track the reference trajectory. Then, the design of incremental multivariable predictive functional control was studied. Simulation and application results show that the proposed control strategy is effective and feasible to improve control performance and robustness of process.

A novel Lyapunov-based three-axis attitude intelligent control approach via allocation scheme is considered in the proposed research to deal with kinematics and dynamics regarding the unmanned aerial vehicle systems. There is a consensus among experts of this field that the new outcomes in the present complicated systems modeling and control are highly appreciated with respect to state-of-the-art. The control scheme presented here is organized in line with a new integration of the linear-nonlinear control approaches, as long as the angular velocities in the three axes of the system are accurately dealt with in the inner closed loop control. And the corresponding rotation angles are dealt with in the outer closed loop control. It should be noted that the linear control in the present outer loop is first designed through proportional based linear quadratic regulator (PD based LQR) approach under optimum coefficients, while the nonlinear control in the corresponding inner loop is then realized through Lyapunov-based approach in the presence of uncertainties and disturbances. In order to complete the inner closed loop control, there is a pulse-width pulse-frequency (PWPF) modulator to be able to handle on-off thrusters. Furthermore, the number of these on-off thrusters may be increased with respect to the investigated control efforts to provide the overall accurate performance of the system, where the control allocation scheme is realized in the proposed strategy. It may be shown that the dynamics and kinematics of the unmanned aerial vehicle systems have to be investigated through the quaternion matrix and its corresponding vector to avoid presenting singularity of the results. At the end, the investigated outcomes are presented in comparison with a number of potential benchmarks to verify the approach performance.

A patch-based method for detecting vehicle logos using prior knowledge is proposed. By representing the coarse region of the logo with the weight matrix of patch intensity and position, the proposed method is robust to bad and complex environmental conditions. The bounding-box of the logo is extracted by a thershloding approach. Experimental results show that 93.58% location accuracy is achieved with 1100 images under various environmental conditions, indicating that the proposed method is effective and suitable for the location of vehicle logo in practical applications.

Lookup table is widely used in automotive industry for the design of engine control units (ECU). Together with a proportional-integral controller, a feed-forward and feedback control scheme is often adopted for automotive engine management system (EMS). Usually, an ECU has a structure of multi-input and single-output (MISO). Therefore, if there are multiple objectives proposed in EMS, there would be corresponding numbers of ECUs that need to be designed. In this situation, huge efforts and time were spent on calibration. In this work, a multi-input and multi-out (MIMO) approach based on model predictive control (MPC) was presented for the automatic cruise system of automotive engine. The results show that the tracking of engine speed command and the regulation of air/fuel ratio (AFR) can be achieved simultaneously under the new scheme. The mean absolute error (MAE) for engine speed control is 0.037, and the MAE for air fuel ratio is 0.069.

The fatigue life of aeroengine turbine disc presents great dispersion due to the randomness of the basic variables, such as applied load, working temperature, geometrical dimensions and material properties. In order to ameliorate reliability analysis efficiency without loss of reliability, the distributed collaborative response surface method (DCRSM) was proposed, and its basic theories were established in this work. Considering the failure dependency among the failure modes, the distributed response surface was constructed to establish the relationship between the failure mode and the relevant random variables. Then, the failure modes were considered as the random variables of system response to obtain the distributed collaborative response surface model based on structure failure criterion. Finally, the given turbine disc structure was employed to illustrate the feasibility and validity of the presented method. Through the comparison of DCRSM, Monte Carlo method (MCM) and the traditional response surface method (RSM), the results show that the computational precision for DCRSM is more consistent with MCM than RSM, while DCRSM needs far less computing time than MCM and RSM under the same simulation conditions. Thus, DCRSM is demonstrated to be a feasible and valid approach for improving the computational efficiency of reliability analysis for aeroengine turbine disc fatigue life with multiple random variables, and has great potential value for the complicated mechanical structure with multi-component and multi-failure mode.

A complete control type plant factory has high efficiency in terms of cultivation area by constructing vertical multiple layered cultivation beds. However, it has a problem of irregular crop growth due to temperature deviation at upper and lower beds and increases in energy consumption by a prolonged cultivation period. In this work, air flow rate inside a facility was improved by a hybrid control of air flow devices like air conditioning and air circulation fan with an established wireless sensor network to minimize temperature deviations between upper and lower beds and to promote crop growth. The performance of proposed system was verified with an experimental environment or Case A wherein air conditioning device was operated without a control algorithm and Case B wherein air conditioning and circulation fans were alternatively operated based on the hybrid control algorithm. After planting leafy vegetables under each experimental condition, crops were cultivated for 21 days. As a result, Case B wherein AC (air conditioning) and ACF (air-circulation fan) were alternatively operated based on the hybrid control algorithm showed that fresh mass, number of leaves, and leaf length for the crops grown were increased by 40.6%, 41.1%, and 11.1%, respectively, compared to Case A.

In radio receivers, complete implementation of the software defined radio (SDR) concept is mainly limited by frontend. Based on bandpass sampling (BPS) theory, a flexible digital frontend (DFE) platform for SDR receiver is designed. In order to increase the processing speed, Gigabit Ethernet was applied in the platform at speed of 5×10⁸ bit/s. By appropriate design of interpolant according to the position of input RF signals, multi-band receiving can be realized in the platform with suppression more than 35 dB without changing hardware.

Fuzzy Petri net (FPN) has been extensively applied in industrial fields for knowledge-based systems or systems with uncertainty. Although the applications of FPN are known to be successful, the theoretical research of FPN is still at an initial stage. To pave a way for further study, this work explores related dynamic properties of FPN including reachability, boundedness, safeness, liveness and fairness. The whole methodology is divided into two phases. In the first phase, a comparison between elementary net system (EN_system) and FPN is established to prove that the FPN is an extensive formalism of Petri nets using a backwards-compatible extension method. Next, current research results of dynamic properties are utilized to analyze FPN model. The results illustrate that FPN model is bounded, safe, weak live and fair, and can support theoretical evidences for designing related decomposition algorithm.

In order to reduce the partial derivative errors in Preisach hysteresis model caused by inaccurate experimental data, the concept and correlative method of discretization of Preisach hysteresis model are proposed, the essential of which is to centralize the distribution density of Preisach hysteresis model in local region as an integral, which is defined as the weight of a certain point in that region. For the input composed of an ascending segment and a descending segment, a method to determine the initial weights together with an additional method to determine present weights is given according to the number of input ascending segments. If the number of input ascending segments increases, the weights of the corresponding points in updating rectangle are updated by adding the initial weights of corresponding points. A prominent advantage of discrete Preisach hysteresis model is its memory efficiency. Another advantage of discrete Preisach hysteresis model is that there is no function in the model, and thus, it can be expediently operated using a computer. By generalizing the above updating rectangle method to the continuous Preisach hysteresis model, identification method of distribution density can be given as well.

Region partition (RP) is the key technique to the finite element parallel computing (FEPC), and its performance has a decisive influence on the entire process of analysis and computation. The performance evaluation index of RP method for the three-dimensional finite element model (FEM) has been given. By taking the electric field of aluminum reduction cell (ARC) as the research object, the performance of two classical RP methods, which are Al-NASRA and NGUYEN partition (ANP) algorithm and the multi-level partition (MLP) method, has been analyzed and compared. The comparison results indicate a sound performance of ANP algorithm, but to large-scale models, the computing time of ANP algorithm increases notably. This is because the ANP algorithm determines only one node based on the minimum weight and just adds the elements connected to the node into the sub-region during each iteration. To obtain the satisfied speed and the precision, an improved dynamic self-adaptive ANP (DSA-ANP) algorithm has been proposed. With consideration of model scale, complexity and sub-RP stage, the improved algorithm adaptively determines the number of nodes and selects those nodes with small enough weight, and then dynamically adds these connected elements. The proposed algorithm has been applied to the finite element analysis (FEA) of the electric field simulation of ARC. Compared with the traditional ANP algorithm, the computational efficiency of the proposed algorithm has been shortened approximately from 260 s to 13 s. This proves the superiority of the improved algorithm on computing time performance.

A method that applies clustering technique to reduce the number of samples of large data sets using input-output clustering is proposed. The proposed method clusters the output data into groups and clusters the input data in accordance with the groups of output data. Then, a set of prototypes are selected from the clustered input data. The inessential data can be ultimately discarded from the data set. The proposed method can reduce the effect from outliers because only the prototypes are used. This method is applied to reduce the data set in regression problems. Two standard synthetic data sets and three standard real-world data sets are used for evaluation. The root-mean-square errors are compared from support vector regression models trained with the original data sets and the corresponding instance-reduced data sets. From the experiments, the proposed method provides good results on the reduction and the reconstruction of the standard synthetic and real-world data sets. The numbers of instances of the synthetic data sets are decreased by 25%-69%. The reduction rates for the real-world data sets of the automobile miles per gallon and the 1990 census in CA are 46% and 57%, respectively. The reduction rate of 96% is very good for the electrocardiogram (ECG) data set because of the redundant and periodic nature of ECG signals. For all of the data sets, the regression results are similar to those from the corresponding original data sets. Therefore, the regression performance of the proposed method is good while only a fraction of the data is needed in the training process.

A systematic analysis of southwestern Ordos Basin’s sedimentary characteristics, internal architectural element association styles and depositional model was illustrated through core statistics, well logging data and outcrop observations in Chang 8 oil-bearing group. This analysis indicates that shallow water delta sediments dominated by a fluvial system is the primary sedimentary system of the Chang 8 oil-bearing group of the Yanchang Formation in southwestern Ordos Basin. Four microfacies with fine grain sizes are identified: distributary channels, sheet sandstone, mouth bar and interdistributary fines. According to the sandbody’s spatial distribution and internal architecture, two types of sandbody architectural element associations are identified: amalgamated distributary channels and thin-layer lobate sandstone. In this sedimentary system, net-like distributary channels at the delta with a narrow ribbon shape compose the skeleton of the sandbody that extends further into the delta front and shades into contiguous lobate distribution sheet sandstone in the distal delta front. The mouth bar is largely absent in this system. By analyzing the palaeogeomorphology, the palaeostructure background, sedimentary characteristics, sedimentary facies types and spatial distribution of sedimentary facies during the Chang 8 period, a distinctive depositional model of the Chang 8 shallow water fluvial-dominated delta was established, which primarily consists of straight multi-phase amalgamated distributary channels in the delta plain, net-like distributary channels frequently diverting and converging in the proximal delta front, sheet sandstones with dispersing contiguous lobate shapes in the distal delta front, and prodelta or shallow lake mudstones.

Time-domain reflectometry was used to make continuous measurements of soil moisture to 18 sample points with depth of 2 m for 36 months in a typical artificial secondary oak forest located in a hilly area on Zijin Mountain in the suburbs of Nanjing, China. The data were then used to examine the patterns of soil moisture variations on temporal and spatial scales and predict the relationships between soil moisture and major factors of both meteorology and topography. Water in the topsoil was active, and the upper 30 cm of soil supplied about 43% of the water content variation during the whole year. This difference of water content changes among layers could be due to the distribution conditions of some soil physical properties. When initial soil moisture was in the range from 10% to 40%, the impact of a single storm event on soil moisture was extremely significant, especially on sunny slope. Both climate and slope condition were related to soil moisture change, and the impact of slope gradient on soil moisture was higher that on shady slope. Moreover, root uptake was another important path of soil water consumption.

Geomechanical parameters are complex and uncertain. In order to take this complexity and uncertainty into account, a probabilistic back-analysis method combining the Bayesian probability with the least squares support vector machine (LS-SVM) technique was proposed. The Bayesian probability was used to deal with the uncertainties in the geomechanical parameters, and an LS-SVM was utilized to establish the relationship between the displacement and the geomechanical parameters. The proposed approach was applied to the geomechanical parameter identification in a slope stability case study which was related to the permanent ship lock within the Three Gorges project in China. The results indicate that the proposed method presents the uncertainties in the geomechanical parameters reasonably well, and also improves the understanding that the monitored information is important in real projects.

The law of blasting vibration caused by blasting in rock is very complex. Traditional numerical methods cannot well characterize all the influencing factors in the blasting process. The effects of millisecond time, charge length and detonation velocity on the blasting vibration are discussed by analyzing the characteristics of vibration wave generated by finite length cylindrical charge. It is found that in multi-hole millisecond blasting, blasting vibration superimpositions will occur several times within a certain distance from the explosion source due to the propagation velocity difference of P-wave and S-wave generated by a short column charge. These superimpositions will locally enlarge the peak velocity of blasting vibration particle. The magnitude and scope of the enlargement are closely related to the millisecond time. Meanwhile, the particle vibration displacement characteristics of rock under long cylindrical charge is analyzed. The results show that blasting vibration effect would no longer increase when the charge length increases to a certain extent. This indicates that the traditional simple calculation method using the maximum charge weight per delay interval to predict the effect of blasting vibration is unreasonable. Besides, the effect of detonation velocity on blasting vibration is only limited in a certain velocity range. When detonation velocity is greater than a certain value, the detonation velocity almost makes no impact on blasting vibration.

Environmental risk assessment of tailings reservoir assessment system is complex and has many index factors. In order to accurately judge surrounding environmental risks of tailings reservoirs and determinate the corresponding prevention and control work, multi-hierarchical fuzzy judgment and nested dominance relation of rough set theory are implemented to evaluate them and find out the rules of this evaluation system with 14 representative cases. The methods of multi-hierarchical fuzzy evaluation can overall consider each influence factor of risk assessment system and their mutual impact, and the index weight based on the analytic hierarchy process is relatively reasonable. Rough set theory based on dominance relation reduces each index attribute from the top down, largely simplifies the complexity of the original evaluation system, and considers the preferential information in each index. Furthermore, grey correlation theory is applied to analysis of importance of each reducted condition attribute. The results demonstrate the feasibility of the proposed safety evaluation system and the application potential.

In order to study rock breaking characteristics of tunnel boring machine (TBM) disc cutter at different rock temperatures, thermodynamic rock breaking mathematical model of TBM disc cutter was established on the basis of rock temperature change by using particle flow code theory and the influence law of interaction mechanism between disc cutter and rock was also numerically simulated. Furthermore, by using the linear cutting experiment platform, rock breaking process of TBM disc cutter at different rock temperatures was well verified by the experiments. Finally, rock breaking characteristics of TBM disc cutter were differentiated and analyzed from microscale perspective. The results indicate the follows. 1) When rock temperature increases, the mechanical properties of rock such as hardness, and strength, were greatly reduced, simultaneously the microcracks rapidly grow with the cracks number increasing, which leads to rock breaking load decreasing and improves rock breaking efficiency for TBM disc cutter. 2) The higher the rock temperature, the lower the rock internal stress. The stress distribution rules coincide with the Buzin Neske stress circle rules: the maximum stress value is below the cutting edge region and then gradually decreases radiant around; stress distribution is symmetrical and the total stress of rock becomes smaller. 3) The higher the rock temperature is, the more the numbers of micro, tensile and shear cracks produced are by rock as well as the easier the rock intrusion, along with shear failure mode mainly showing. 4) With rock temperature increasing, the resistance intrusive coefficients of rock and intrusion power decrease obviously, so the specific energy consumption that TBM disc cutter achieves leaping broken also decreases subsequently. 5) The acoustic emission frequency remarkably increases along with the temperature increasing, which improves the rock breaking efficiency.

The purpose of this work was to explore the influence law of vibration load on rock mass structure and slope stability. Based on the type and transmission way of vibration stress wave, the main stress in the horizontal and vertical directions was analyzed and the superposition effect of the stress wave was revealed. After the mechanical analysis of the sliding mass, the calculation formulas of the anti-sliding force and the sliding force were derived and the damage mechanism of blasting vibration to the structural plane was defined. In addition, according to the structure and lithologic parameter of the slope as well as the vibration monitoring data, the west slope stability of Xiaolongtan open pit mine was analyzed. The results show that the time-dependent stability factor is proportional to the vibration speed and the peak values appear at the same time. Vibration load promotes the breakage of the structural plane leading to the drop of the west slope stability factor by 0.23%. Under the multipoint simultaneous blasting, the fluctuating laws of the stability factors are consistent. The more the start-up points are, the higher the weakening degree to the slope stability is. Under the multipoint allochronic blasting, the stability factor depends on the synthetic waveform structure of all vibration waves. The greater the blasting time difference is, the lower the weakening degree to the slope stability is. Selecting the reasonable quantity of start-up points and time difference could fully reduce the adverse influence of vibration load to slope stability.

Characteristic of cyclic loading due to passing wheels is associated with one-way loading without stress reversal, which includes a simultaneous cyclic variation of vertical normal stress and horizontal normal stress lasting for a long period of time and generally takes place in partially-drained conditions. Therefore, it is of great practical relevance to study the deformation behaviour according to the characteristic of traffic loading. In this work, a series of one-way stress-controlled cyclic triaxial tests with a simultaneous variation of the vertical and horizontal stress components during cyclic loading were conducted to investigate the deformation behaviour of natural K₀-consolidated soft clay in partially-drained conditions. Test results demonstrate that not only the deviator part of the stress rules accumulation but also the volumetric part significantly contributes. While the deviator part of the stress amplitude is held constant, the increase amplitude of cyclic confining pressure will promote the development of both permanent volumetric strain and axial strain significantly. Furthermore, the effects of cyclic confining pressure on the deformation of natural K₀-consolidated soft clay was quantified. Finally, an empirical formula for permanent axial strain considering the effects of cyclic confining pressure was proposed which can be used for feasibility studies or for the preliminary design of foundations on K₀-consolidated soft clay subjected to traffic loading.

Engineering property of kaolin clay contaminated by diesel oil was studied through a series of laboratory experiments. Oil contents (mass fraction) of 4%, 8%, 12%, 16% and 20% were selected to represent different contamination degrees, and the soil specimens were manually prepared through mixing and static compaction method. Initial water content and dry density of the test kaolin clay were controlled at 10% and 1.58 g/cm³, respectively. Test results indicate that since part of the diesel oil will be released from soil by evaporation, the real water content should be derived through calibration of the quasi water content obtained by traditional test method. As contamination degree of the kaolin clay increases, both liquid limit and plastic limit decrease, but there’s only a slight increase for plasticity index. Swelling pressure of contaminated kaolin clay under confined condition will be lowered when oil-content gets higher. Unconfined compressive strength (UCS) of the oil-contaminated kaolin clay is influenced by not only oil content but also curing period. Increase of contamination degree will continually lower UCS of the kaolin clay specimen. In addition, electrical resistivity of the contaminated kaolin clay with given water content decreases with the increase of oil content. However, soil resistivity is in good relationship with oil content and UCS. Finally, oil content of 8% is found to be a critical value for engineering property of kaolin clay to transit from water-dominated towards oil-dominated characteristics.

A micromechanical investigation on simple shear behavior of dense granular assemblies was carried out by discrete element method. Three series of numerical tests were performed to examine the effects of initial porosity, vertical stress and particle shape on simple shear behavior of the samples, respectively. It was found that during simple shear the directions of principal stress and principal strain increment rotate differently with shear strain level. The non-coaxiality between the two directions decreases with strain level and may greatly affect the shear behavior of the assemblies, especially their peak friction angles. The numerical modelling also reveals that the rotation of the principal direction of fabric anisotropy lags behind that of the major principal stress direction during simple shear, which is described as fabric hyteresis effect. The degrees of fabric and interparticle contact force anisotropies increase as particle angularity increases, whereas the orientations of these anisotropies have not been significantly influenced by particle shape. An extended stress-dilatancy relationship based on ROWE-DAVIS framework was proposed to consider the non-coaxiality effect under principal stress rotation. The model was validated by present numerical results as well as some published physical test and numerical modelled data.

An analysis of unsteady boundary layer flow and heat transfer over an exponentially shrinking porous sheet filled with a copper-water nanofluid is presented. Water is treated as a base fluid. In the investigation, non-uniform mass suction through the porous sheet is considered. Using Keller-box method the transformed equations are solved numerically. The results of skin friction coefficient, the local Nusselt number as well as the velocity and temperature profiles are presented for different flow parameters. The results showed that the dual non-similar solutions exist only when certain amount of mass suction is applied through the porous sheet for various unsteady parameters and nanoparticle volume fractions. The ranges of suction where dual non-similar solution exists, become larger when values of unsteady parameter as well as nanoparticle volume fraction increase. So, due to unsteadiness of flow dynamics and the presence of nanoparticles in flow field, the requirement of mass suction for existence of solution of boundary layer flow past an exponentially shrinking sheet is less. Furthermore, the velocity boundary layer thickness decreases and thermal boundary layer thickness increases with increasing of nanoparticle volume fraction in both non-similar solutions. Whereas, for stronger mass suction, the velocity boundary layer thickness becomes thinner for the first solution and the effect is opposite in the case of second solution. The temperature inside the boundary layer increases with nanoparticle volume fraction and decreases with mass suction. So, for the unsteadiness and for the presence of nanoparticles, the flow separation is delayed to some extent.

Non-equilibrium vapor condensation of moist gas through a sonic nozzle is a very complicated phenomenon and is related to the measurement accuracy of sonic nozzle. A gas-liquid two-phase model for the moist gas condensation flow was built and validated by moist nitrogen experiment of homogeneous nucleation through a transonic nozzle. The effects of carrier gas pressure on position and status of condensation onset in sonic nozzle were investigated in detail. The results show that condensation process is not easy to occur at lower carrier pressure and throat diameter. The main factors influencing condensation onset are boundary layer thickness, heat capacity of carrier gas and expansion rate. All of results can be used to further analyze the effect of condensation on mass flow-rate of sonic nozzle.

This work presented the development and validation of an analytical method to predict the transient temperature field in the asphalt pavement. The governing equation for heat transfer was based on heat conduction radiation and convection. An innovative time-dependent function was proposed to predict the pavement surface temperature with solar radiation and air temperature using dimensional analysis in order to simplify the complex heat exchange on the pavement surface. The parameters for the time-dependent pavement surface temperature function were obtained through the regression analysis of field measurement data. Assuming that the initial pavement temperature distribution was linear and the influence of the base course materials on the temperature of the upper asphalt layers was negligible, a close-form analytical solution of the temperature in asphalt layers was derived using Green’s function. Finally, two numerical examples were presented to validate the model solutions with field temperature measurements. Analysis results show that the solution accuracy is in agreement with field data and the relative errors at a shallower depth are greater than those at a deeper one. Although the model is not sensitive to dramatic changes in climatic factors near the pavement surface, it is applicable for predicting pavement temperature field in cloudless days.

To maintain their capacity, transportation infrastructures are in need of regular maintenance and rehabilitation. The major challenge facing transportation engineers is the network-level policies to maintain the deteriorating roads at an acceptable level of serviceability. In this work, a quantitative transportation network efficiency measure is presented and then how to determine optimally network-level road maintenance policy depending on the road importance to the network performance has been demonstrated. The examples show that the different roads should be set different maintenance time points in terms of the retention capacities of the roads, because the different roads play different roles in network and have different important degrees to the network performance. This network-level road maintenance optimization method could not only save lots of infrastructure investments, but also ensure the service level of the existing transportation system.

This work aimed to explore the switch tendency of bicycle use between cyclists and non-cyclists. The attitude based market segmentation approach was proposed to achieve the research objective. The filed investigations were conducted in Nanjing, China, to obtain travelers’ actions and attitudes towards bicycle uses. The structural equation modeling (SEM) was used to identify the attitudinal factors indicating variables and to explore the interrelationships among them. The SEMs were developed separately for the cyclist group and the non-cyclist group. All respondents were clustered into eight distinct segments by six selected attitudinal factors. The mode switch tendency and attitude in each segment is different from others, indicating that different segments have particular policies or strategies to encourage cycling. Policy implications that best serve the potential bicycle users were discussed to reduce the number of cyclists who have high tendency to use other modes, and increase the possibility of using bicycle in the non-cyclists group with the moderate and high switch tendency.