The effects of chloride, sulfate and carbonate anions on stress corrosion behaviors of ultra-high strength steel 23Co14Ni12Cr3Mo were studied by stress corrosion cracking (SCC) test method using double cantilever beam (DCB) specimens. The SCC morphology was observed by using scanning electron microscopy (SEM) and the composition of corrosion products was analyzed by using energy dispersive spectrometer (EDS). The results show that the crack propagates to bifurcation in NaCl and Na₂SO₄ solution, while the crack in Na₂CO₃ solution propagates along the load direction. The SCC rate in NaCl solution is the highest, while lower in Na₂SO₄ solution and little in Na₂CO₃ solution. From the SEM morphologies, quasi-cleavage fracture was observed in NaCl and Na₂SO₄ solutions, but intergranular features in Na₂CO₃ solution. The mechanism of anion effect on SCC of steel 23Co14Ni12Cr3Mo was studied by using full immersion test and electrochemical measurements.

The La-Mg-Ni-based A₂B₇-type La_0.8Mg_0.2Ni_3.3Co_0.2Si_x (x=0–0.2) electrode alloys were prepared by casting and annealing. The influences of the additional silicon and the annealing treatment on the structure and electrochemical performances of the alloys were investigated systemically. Both of the analyses of XRD and SEM reveal that the as-cast and annealed alloys are of a multiphase structure, involving two main phases (La, Mg)₂Ni₇ and LaNi₅ as well as one minor phase LaNi₃. The addition of Si and annealing treatment bring on an evident change in the phase abundances and cell parameters of (La, Mg)₂Ni₇ and LaNi₅ phase for the alloy without altering its phase structure. The phase abundances decrease from 74.3% (x=0) to 57.8% (x=0.2) for the (La, Mg)₂Ni₇ phase, and those of LaNi5 phase increase from 20.2% (x=0) to 37.3% (x=0.2). As for the electrochemical measurements, adding Si and performing annealing treatment have engendered obvious impacts. The cycle stability of the alloys is improved dramatically, being enhanced from 80.3% to 93.7% for the as-annealed (950 °C) alloys with Si content increasing from 0 to 0.2. However, the discharge capacity is reduced by adding Si, from 399.4 to 345.3 mA·h/g as the Si content increases from 0 to 0.2. Furthermore, such addition makes the electrochemical kinetic properties of the alloy electrodes first increase and then decrease. Also, it is found that the overall electrochemical properties of the alloys first augment and then fall with the annealing temperature rising.

With the substitution of part Mg in LaMg₃ by Cu, the elastic constants C₁₁ and C₁₂ increase while C₄₄ decreases, implying an enhanced Poisson effect and smaller resistance to 〈001〉(100) shear. Furthermore, the bulk modulus B increases, while the shear modulus G, elastic modulus E and anisotropic ratio A are reduced. The calculated Debye temperature of LaCuMg₂ is lower, implying the weaker interaction between atoms in LaCuMg₂. Then, the stress-strain curves in entire range and the ideal strength at critical strain are studied. The present results show that the lowest ideal tensile strength for LaMg₃ and LaCuMg₂ is in the 〈100〉 direction. The ideal shear strength on the

A novel synthesis of LiFePO₄/C from Fe₂O₃ with no extra carbon or carbon-containing reductant was introduced: Fe₂O₃ (+NH₄H₂PO₄)→Fe₂P₂O₇(+Li₂CO₃+glucose)→LiFePO₄/C. X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were utilized to characterize relevant products obtained in the synthetic procedure. The reaction of Fe₂P₂O₇ and Li₂CO₃ was investigated by thermo-gravimetric and differential thermal analysis (TGA-DTA). Fe₂O₃ is completely reduced to Fe₂P₂O₇ by NH₄H₂PO₄ at 700 °C and Fe₂P₂O₇ fully reacts with Li₂CO₃ to form LiFePO₄ in the temperature range of 663.4–890 °C. The primary particles of LiFePO₄/C samples prepared at 670, 700 and 750 °C respectively exhibit uniform morphology and narrow size distribution, 0.5–3 μm for those obtained at 670 and 700 °C and 0.5–5 μm for those obtained at 750 °C. LiFePO₄/C (carbon content of 5.49%, mass fraction) made at 670 °C shows an appreciable average capacity of 153.2 mA·h/g at 0.1C in the first 50 cycles.

A theoretical investigation of fluid flow, heat transfer and solidification (solidification transfer phenomena, STP) was presented which coupled with direct-current (DC) magnetic fields in a high-speed strip-casting metal delivery system. The bidirectional interaction between the STP and DC magnetic fields was simplified as a unilateral one, and the fully coupled solidification transport equations were numerically solved by the finite volume method (FVM). While the magnetic field contours for a localized DC magnetic field were calculated by software ANSYS and then incorporated into a three-dimensional (3-D) steady model of the liquid cavity in the mold by means of indirect coupling. A new FVM-based direct-SIMPLE algorithm was adopted to solve the iterations of pressure-velocity (P-V). The braking effects of DC magnetic fields with various configurations were evaluated and compared with those without static magnetic field (SMF). The results show that 0.6 T magnetic field with combination configuration contributes to forming an isokinetic feeding of melt, the re-circulation zone is shifted towards the back wall of reservoir, and the velocity difference on the direction of height decreases from 0.1 m/s to 0. Furthermore, the thickness of solidified skull increases uniformly from 0.45 mm to 1.36 mm on the chilled substrate (belt) near the exit.

Aiming at accuracy control of the thermal crown of work rolls in cold rolling, new parameters such as regulation domain and control-efficiency factors were proposed and a numerical analysis model of the thermal crown of work rolls was established using finite difference method to study roll’s thermal deformation. Based on simulation results, the influences of control-efficiency factors on thermal crown are presented and the thermal crown of work rolls is analyzed after taking sub-cooling of sprinkling beam into consideration. It has been found that the control-efficiency factor of any position on the roll’s surface is linear function of the temperature and the control ability of water temperature is stronger than other control parameters. In addition, the verification of the model has been carried out based on the producing technology data in some factories and the numerical simulation results coincide well with the experimental data. Therefore, this work has important value for on-line control of roll’s crown in cold rolling.

The effects of magnetic field intensity, roasting temperature and roasting time on digestion rate and settling performance of bauxite with different iron contents were investigated systematically. The results indicate that such magnetic treatment can profoundly change the microstructure and digestion performance of bauxite. For the two samples carrying different iron contents, phase transformation of the aluminum oxide phase proceeds faster in the high iron bauxite than the low one. The optimal pretreatment conditions of low iron bauxite are roasting temperature 550 °C and magnetic field intensity 6 T, while for high iron bauxite are 500 °C and 9 T. The digestion rate of alumina can reach 95% and 92% at digestion temperature of 190 °C and 250 °C. The settling performances of roasted ore by intense magnetic field after digestion are enhanced through pretreatment.

The kinetics of leaching arsenic from Ni-Mo ore roasting dust was investigated. The effects including leaching temperature, particle size of the smelter dust, stirring speed, the coefficient β (the molar ratio of sodium chlorate to arsenic in the smelter dust) and the initial H+ concentration on leaching arsenic were studied. The results indicate that the leaching of arsenic increases sharply with the decrease of particle size. The orders of reaction with respect to H⁺ concentration and particle size are determinted to be 1.136 and −1.806, respectively. The leaching of arsenic reaches 99% under experimental conditions, the apparent activation energy is determined to be 11.157 kJ/mol, which is consistent with the values of activation energy for diffusion model. The kinetics equation of leaching arsenic from the roasting dust could be expressed by a semi-empirical equation as

A systematic study of air gap distance effects on the structure and properties of poly(vinyl butyral) hollow fiber membrane via thermally induced phase separation (TIPS) has been carried out. The results show that the hollow fiber membrane prepared at air gap zero has no skin layer; the pore size near the outer surface is larger than that near the inner surface; and the special pore channel-like structure near the outer surface is formed, which is quite different with the typical sponge-like structure caused by TIPS and the finger-like structure caused by non-solvent induced phase separation (NIPS), because of the synergistic action of non-solvent induced phase separation at air gap zero. The pore size gradually decreases from outer surface layer to the intermediate layer, but increases gradually from intermediate layer to the inner surface layer. With the increase of air gap distance, the pore size near the outer surface gets smaller and a dense skin layer is formed, and the pore size gradually increases from the outer surface layer to the inner surface layer. Water permeability of the hollow fiber membrane decreases with air gap distance, the water permeability decreases sharply from 45.50×10⁻⁷ to 4.52×10⁻⁷ m³/(m²·s·kPa) as air gap increases from 0 to 10 mm at take-up speed of 0.236 m/s, further decreases from 4.52×10⁻⁷ to 1.00×10⁻⁸ m³/(m²·s·kPa) as the air gap increases from 10 to 40 mm. Both the breaking strength and the elongation increase with the increase of air gap distance. The breaking strength increases from 2.25 MPa to 4.19 MPa and the elongation increases from 33.9% to 132.6% as air gap increases from 0 mm to 40 mm at take-up speed 0.236 m/s.

The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization (ECMP) at different pH values including 5-methyl-1H-benzotriazole (TTA), hydroxyethylidenediphosphoric acid (HEDP), and tribasic ammonium citrate (TAC) were investigated by electrochemical techniques, X-ray photoelectron spectrometer (XPS) analysis, nano-scratch tests, AFM measurements, and polishing of Cu-coated blanket wafers. The experimental results show that the planarization efficiency and the surface quality after ECMP obtained in alkali-based solutions are superior to that in acidic-based solutions, especially at pH=8. The optimal electrolyte compositions (mass fraction) are 6% HEDP, 0.3% TTA and 3% TAC at pH=8. The main factor affecting the thickness of the oxide layer formed during ECMP process is the applied potential. The soft layer formation is a major mechanism for electrochemical enhanced mechanical abrasion. The surface topography evolution before and after electrochemical polishing (ECP) illustrates the mechanism of mechanical abrasion accelerating electrochemical dissolution, that is, the residual stress caused by the mechanical wear enhances the electrochemical dissolution rate. This understanding is beneficial for optimization of ECMP processes.

A polypyrrole-modified glassy carbon electrode (PPy/GC electrode) was prepared and its electrocatalytic behavior towards naphthoquinone in the presence of acid was characterized by linear sweep voltammetry (LSV). A well-defined new reduction peak appeared at a more positive potential than the original reduction peak. The new reduction peak current was linearly related to the acid value (AV) of oil. Based on it, a rapid electrochemical method for determining AV of transformer oil was developed using PPy/GC electrode. A working curve was obtained in the AV range of 0.01 to 0.40 mg(KOH)·g⁻¹, with a sensitivity of 39.42 μA_0.5/(mg(KOH)·g⁻¹) and the detection limit of 0.0014 mg(KOH)·g⁻¹ (signal-to-noise ratio is 3, standard deviation is 2.247%). Moreover, the proposed method has been successfully applied to AV determination of several transformer oil samples with advantages of rapidness, high sensitivity and accuracy compared to the conventional method.

The task of simultaneous localization and mapping (SLAM) is to build environmental map and locate the position of mobile robot at the same time. FastSLAM 2.0 is one of powerful techniques to solve the SLAM problem. However, there are two obvious limitations in FastSLAM 2.0, one is the linear approximations of nonlinear functions which would cause the filter inconsistent and the other is the “particle depletion” phenomenon. A kind of PSO & H_∞-based FastSLAM 2.0 algorithm is proposed. For maintaining the estimation accuracy, H_∞ filter is used instead of EKF for overcoming the inaccuracy caused by the linear approximations of nonlinear functions. The unreasonable proposal distribution of particle greatly influences the pose state estimation of robot. A new sampling strategy based on PSO (particle swarm optimization) is presented to solve the “particle depletion” phenomenon and improve the accuracy of pose state estimation. The proposed approach overcomes the obvious drawbacks of standard FastSLAM 2.0 algorithm and enhances the robustness and efficiency in the parts of consistency of filter and accuracy of state estimation in SLAM. Simulation results demonstrate the superiority of the proposed approach.

In order to ensure that the off-line arm of a two-arm-wheel combined inspection robot can reliably grasp the line in case of autonomous obstacle crossing, a control method is proposed for line grasping based on hand-eye visual servo. On the basis of the transmission line’s geometrical characteristics and the camera’s imaging principle, a line recognition and extraction method based on structure constraint is designed. The line’s intercept and inclination are defined in an imaging space to represent the robot’s change of pose and a law governing the pose decoupling servo control is developed. Under the integrated consideration of the influence of light intensity and background change, noise (from the camera itself and electromagnetic field) as well as the robot’s kinetic inertia on the robot’s imaging quality in the course of motion and the grasping control precision, a servo controller for grasping the line of the robot’s off-line arm is designed with the method of fuzzy control. An experiment is conducted on a 1:1 simulation line using an inspection robot and the robot is put into on-line operation on a real overhead transmission line, where the robot can grasp the line within 18 s in the case of autonomous obstacle-crossing. The robot’s autonomous line-grasping function is realized without manual intervention and the robot can grasp the line in a precise, reliable and efficient manner, thus the need of actual operation can be satisfied.

The sensor array calibration methods tailored to uniform rectangular array (URA) in the presence of mutual coupling and sensor gain-and-phase errors were addressed. First, the mutual coupling model of the URA was studied, and then a set of steering vectors corresponding to distinct locations were numerically computed with the help of several time-disjoint auxiliary sources with known directions. Then, the optimization modeling with respect to the array error matrix (defined by the product of mutual coupling matrix and sensor gain-and-phase errors matrix) was constructed. Two preferable algorithms (called algorithm I and algorithm II) were developed to minimize the cost function. In algorithm I, the array error matrix was regarded as a whole parameter to be estimated, and the exact solution was available. Compared to some existing algorithms with the similar computation framework, algorithm I can make full use of the potentially linear characteristics of URA’s error matrix, thus, the calibration precision was obviously enhanced. In algorithm II, the array error matrix was decomposed into two matrix parameters to be optimized. Compared to algorithm I, it can further decrease the number of unknowns and, thereby, yield better estimation accuracy. However, algorithm II was incapable of producing the closed-form solution and the iteration operation was unavoidable. Simulation results validate the excellent performances of the two novel algorithms compared to some existing calibration algorithms.

Twin-rotor cylinder-embedded piston engine is proposed for dealing with the sealing problems of rotors in twin-rotor piston engine where the existent mature sealing technologies for traditional reciprocating engine can be applied. The quantity and forms of its sealing surfaces are reduced and simplified, and what’s more, the advantages of twin-rotor piston engine are inherited, such as high power density and no valve mechanism. Given the motion law of two rotors, its kinematic model is established, and the general expression for some parameters related to engine performance, such as the trajectory, displacement, velocity and acceleration of the piston and centroid trajectory, angular displacement, velocity and acceleration of the rod are presented. By selecting different variation patterns of relative angle of two rotors, the relevant variables are compared. It can be concluded that by designing the relative angle function of two rotors, the volume variation of working chamber can be changed. However, a comprehensive consideration for friction and vibration is necessary because velocity and acceleration are quite different in the different functions, the swing magnitude of rod is proportional to link ratio λ, and the position of rod swing center is controlled by eccentricity e. In order to reduce the lateral force, a smaller value of λ should be selected in the case of the structure, and the value of e should be near 0.95. There is no relationship between the piston stroke and the variation process of relative angle of two rotors, the former is only proportional to the amplitude of relative angle of two rotors.

Switching expansion reduction (SER) uses a switch valve instead of the throttle valve to realize electronically controlled pressure reduction for high pressure pneumatics. A comprehensive and interactive pneumatic simulation model according to the experimental setup of SER has been built. The mathematical model considers heat exchanges, source air pressure and temperature, environmental temperatures and heat transfer coefficients variations. In addition, the compensation for real gas effect is used in the model building. The comparison between experiments and simulations of SER indicates that, to compensate the real gas effect in high pressure discharging process, the thermal capacity of air supply container in simulation should be less than the actual value. The higher the pressure range, the greater the deviation. Simulated and experimental results are highly consistent within pressure reduction ratios ranging from 1.4 to 20 and output air mass flow rates ranging from 3.5 to 132 g/s, which verifies the high adaptability of SER and the validity of the mathematic model and the compensation method.

The problems of joint adaptive waveform design and baseline range design for bistatic radar to maximize the practical radar resolution were considered. Distinguishing from the conventional ambiguity function (AF)-based resolution which is only related with the transmitted waveform and bistatic geometry and could be regarded as the potential resolution of a bistatic radar system, the practical resolution involves the effect of waveform, signal-to-noise ratio (SNR) as well as the measurement model. Thus, it is more practical and will have further significant application in target detection and tracking. The constraint optimization procedure of joint adaptive waveform design and baseline range design for maximizing the practical resolution of bistatic radar system under dynamic target scenario was devised. Simulation results show that the range and velocity resolution are enhanced according to the adaptive waveform and bistatic radar configuration.

Fault diagnostics is an important research area including different techniques. Principal component analysis (PCA) is a linear technique which has been widely used. For nonlinear processes, however, the nonlinear principal component analysis (NLPCA) should be applied. In this work, NLPCA based on auto-associative neural network (AANN) was applied to model a chemical process using historical data. First, the residuals generated by the AANN were used for fault detection and then a reconstruction based approach called enhanced AANN (E-AANN) was presented to isolate and reconstruct the faulty sensor simultaneously. The proposed method was implemented on a continuous stirred tank heater (CSTH) and used to detect and isolate two types of faults (drift and offset) for a sensor. The results show that the proposed method can detect, isolate and reconstruct the occurred fault properly.

In the tracking problem for the maritime radiation source by a passive sensor, there are three main difficulties, i.e., the poor observability of the radiation source, the detection uncertainty (false and missed detections) and the uncertainty of the target appearing/disappearing in the field of view. These difficulties can make the establishment or maintenance of the radiation source target track invalid. By incorporating the elevation information of the passive sensor into the automatic bearings-only tracking (BOT) and consolidating these uncertainties under the framework of random finite set (RFS), a novel approach for tracking maritime radiation source target with intermittent measurement was proposed. Under the RFS framework, the target state was represented as a set that can take on either an empty set or a singleton; meanwhile, the measurement uncertainty was modeled as a Bernoulli random finite set. Moreover, the elevation information of the sensor platform was introduced to ensure observability of passive measurements and obtain the unique target localization. Simulation experiments verify the validity of the proposed approach for tracking maritime radiation source and demonstrate the superiority of the proposed approach in comparison with the traditional integrated probabilistic data association (IPDA) method. The tracking performance under different conditions, particularly involving different existence probabilities and different appearance durations of the target, indicates that the method to solve our problem is robust and effective.

The effect of substrate doping on the threshold voltages of buried channel pMOSFET based on strained-SiGe technology was studied. By physically deriving the models of the threshold voltages, it is found that the layer which inversely occurs first is substrate doping dependent, giving explanation for the variation of plateau observed in the C-V characteristics of this device, as the doping concentration increases. The threshold voltages obtained from the proposed model are −1.2805 V for buried channel and −2.9358 V for surface channel at a lightly doping case, and −3.41 V for surface channel at a heavily doping case, which agrees well with the experimental results. Also, the variations of the threshold voltages with several device parameters are discussed, which provides valuable reference to the designers of strained-SiGe devices.

With the growing deployment of smart distribution grid, it has become urgent to investigate the smart distribution grid behavior during transient faults and improve the system stability. The feasibility of segmenting large power grids and multiple smart distribution grids interconnections using energy storage technology for improving the system dynamic stability was studied. The segmentation validity of the large power grids and smart distribution grid inverter output interconnections power system using energy storage technology was proved in terms of theoretical analysis. Then, the influences of the energy storage device location and capacity on the proposed method were discussed in detail. The conclusion is obtained that the ESD optimal locations are allocated at the tie line terminal buses in the interconnected grid, respectively. The effectiveness of the proposed method was verified by simulations in an actual power system.

A novel moving object detection method was proposed in order to adapt the difficulties caused by intermittent object motion, thermal and dynamic background sequences. Two groups of complementary Gaussian mixture models were used. The ghost and real static object could be classified by comparing the similarity of the edge images further. In each group, the multi resolution Gaussian mixture models were used and dual thresholds were applied in every resolution in order to get a complete object mask without much noise. The computational color model was also used to depress illustration variations and light shadows. The proposed method was verified by the public test sequences provided by the IEEE Change Detection Workshop and compared with three state-of-the-art methods. Experimental results demonstrate that the proposed method is better than others for all of the evaluation parameters in intermittent object motion sequences. Four and two in the seven evaluation parameters are better than the others in thermal and dynamic background sequences, respectively. The proposed method shows a relatively good performance, especially for the intermittent object motion sequences.

The performances of repaired image depend on the local information in the repaired area and the consistency between the repair directions with structural content. Image repair algorithm with texture information performs well in repairing seriously damaged images, but it has bad performances when the images have the abundant structure information. The dual optimization image repair algorithm based on the linear structure and the optimal texture is proposed. The algorithm uses the double-constraint sparse model to reconstruct the missed information in large area in order to improve the clarity of repaired images. After adopting the preference of Criminisi priority, the image repair algorithm of self-similarity characteristics is proposed to improve the fault and fuzzy distortion phenomena in the repaired image. The results show that the proposed algorithm has more clarity in the image texture and structure and better effectiveness, and the peak signal-to-noise ratio of the repaired images by proposed algorithm is superior to that by other algorithms.

Aiming at the group of autonomous agents consisting of multiple leader agents and multiple follower ones, a flocking behavior method with multiple leaders and a global trajectory was proposed. In this flocking method, the group leaders can attain the information of the global trajectory, while each follower can communicate with its neighbors and corresponding leader but does not have global knowledge. Being to a distributed control method, the proposed method firstly sets a movable imaginary point on the global trajectory to ensure that the center and average velocity of the leader agents satisfy the constraints of the global trajectory. Secondly, a two-stage strategy was proposed to make the whole group satisfy the constraints of the global trajectory. Moreover, the distance between the center of the group and the desired trajectory was analyzed in detail according to the number ratio of the followers to the leaders. In this way, on one hand, the agents of the group emerge a basic flocking behavior; on the other hand, the center of the group satisfies the constraints of global trajectory. Simulation results demonstrate the effectiveness of the proposed method.

As for ultra-low permeability reservoir, the adaptability of common nine-spot well pattern is studied through large-scale flat models made by micro-fractured natural sandstone outcrops. Combined with non-linear porous flow characteristics, the concept of dimensionless pressure sweep efficiency and deliverability index are put forward to evaluate the physical models’ well pattern adaptability. Through experiments, the models’ pressure distribution is measured and on which basis, the pressure gradient fields are drawn and the porous flow regions of these models are divided into dead oil region, non-linear porous flow region, and quasi-linear porous flow region with the help of twin-core non-linear porous flow curve. The results indicate that rectangular well pattern in fracture reservoirs has the best adaptability, while the worst is inverted nine-spot equilateral well pattern. With the increase of drawdown pressure, dead oil region decreases, pressure sweep efficiency and deliverability index increase; meantime, the deliverability index of rectangular well pattern has much more rational increase. Under the same drawdown pressure, the rectangular well pattern has the largest pressure sweep efficiency.

Effective thermal performance of oscillating heat pipe (OHP) is driven by inside pressure distribution. Heat transfer phenomena were reported in terms of pressure and frequency of pressure fluctuation in multi loop OHP charged with aqueous Al₂O₃ and MWCNTs/Al₂O₃ nanoparticles. The influences on thermal resistance of aqueous Al₂O₃, MWCNTs as well as the hybrid of them in OHP having 3 mm in inner diameter were investigated at 60% filling ratio. Experimental results show that thermal characteristics are significantly inter-related with pressure distribution and strongly depend upon the number of pressure fluctuations with time. Frequency of pressure depends upon the power input in evaporative section. A little inclusion of MWCNTs into aqueous Al₂O₃ at 60% filling ratio achieves the highest fluctuation frequency and the lowest thermal resistance at any evaporator power input though different nanofluids cause different thermal performances of OHPs.

The heavy metal (such as Cr, Ni, Cu, Cd, Pb, and Zn) concentration, speciation, and pollution source in 43 sediment samples from the Xiangjiang River were investigated using sequential extraction combined with Pb isotope analysis. Cu, Cd, Pb, and Zn concentrations are higher than their background values, while Cr and Ni concentrations are close to those. Sequential extraction demonstrates that heavy metals have different fractions, showing different bioavailabilities. The w(²⁰⁶Pb)/w(²⁰⁷Pb) ratio increases with decreasing bioavailability in the order of exchangeable<carbonate≈Fe-Mn oxides≈organic<residual (p<0.05). Wastewater, dust, and slag from mining and smelting areas, and the residual Pb are assumed to be the primary anthropogenic and natural sources of Pb, respectively. The percentages of anthropogenic Pb in the exchangeable, carbonate, Fe-Mn oxides, and organic fractions are (91.5±16.7)%, (61.1±13.9)%, (57.4±11.1)%, and (55.5±11.2)%, respectively, suggesting a significant input of anthropogenic Pb in these four fractions.

In order to greatly improve adsorption capacity, the diatomite was pillared by polyhydroxyl-aluminum. A series of adsorption tests were conducted to obtain the optimum condition for pillared diatomite synthesis. The scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), surface area and porosity analyzer and micro-electrophoresis were used to determine pore structure and surface property. The pillared diatomite attaining the optimal adsorption densities (q_e) of Pb²⁺ and Cd²⁺ was synthesized with the following conditions: Addition of pillaring solution containing Al³⁺-oligomers with a concentration range of 0.1–0.2 mol/L to a suspension containing Na+-diatomite to obtain the required Al/diatomite ratio of 10 mmol/g; synthesis temperature of 80 °C for 120 min; aging at a temperature of 105 °C for 16 h. The adsorption capacities of Pb²⁺ and Cd²⁺ on pillared diatomite increase by 23.79% and 27.36% compared with natural diatomite, respectively. The surface property of pillared diatomite is more favorable for ion adsorption than natural diatomite. The result suggests that diatomite can be modified by pillaring with polyhydroxyl-aluminum to improve its adsorption properties greatly.

Environmental impact evaluation system boundary of high-speed railway was defined based on the total life cycle theory, and the index system to evaluate the environmental impact of high-speed railway was established with the fuzzy analytic hierarchy method, and the matter-element evaluation model was established on the basis of the extension theory. By calculating its comprehensive interrelatedness, the evaluation rank of environment impacts of high-speed railway was determined. The numerical example shows that the model has vast prospect, which can not only expand the application areas of extension theory, but also change the traditional evaluation methods and provide new ideas and means for environmental impact evaluation of high-speed railway.

Equipment plays an important role in open pit mining industry and its cost competence at efficient operation and maintenance techniques centered on reliability can lead to significant cost reduction. The application of optimal maintenance process was investigated for minimizing the equipment breakdowns and downtimes in Sungun Copper Mine. It results in the improved efficiency and productivity of the equipment and lowered expenses as well as the increased profit margin. The field operating data of 10 trucks are used to estimate the failure and maintenance profile for each component, and modeling and simulation are accomplished by using reliability block diagram method. Trend analysis was then conducted to select proper probabilistic model for maintenance profile. Then reliability of the system was evaluated and importance of each component was computed by weighted importance measure method. This analysis led to identify the items with critical impact on availability of overall equipment in order to prioritize improvement decisions. Later, the availability of trucks was evaluated using Monte Carlo simulation and it is revealed that the uptime of the trucks is around 11000 h at 12000 operation hours. Finally, uncertainty analysis was performed to account for the uncertainty sources in data and models.

The size of bubbles created in the flotation process is of great importance to the efficiency of the mineral separation achieved. Meanwhile, it is believed that frother transport between phases is perhaps the most important reason for the interactive nature of the phenomena occurring in the bulk and froth phases in flotation, as frother adsorbed in the surface of rising bubbles is removed from the bulk phase and then released into the froth as a fraction of the bubbles burst. This causes the increased concentration in the froth compared to the bulk concentration, named as frother partitioning. Partitioning reflects the adsorption of frother on bubbles and how to influence bubble size is not known. There currently exists no such a topic aiming to link these two key parameters. To fill this vacancy, the correspondence between bubble size and frother partitioning was examined. Bubble size was measured by sampling-for-imaging (SFI) technique. Using total organic carbon (TOC) analysis to measure the frother partitioning between froth and bulk phases was determined. Measurements have shown, with no exceptions including four different frothers, higher frother concentration is in the bulk than in the froth. The results also show strong partitioning giving an increase in bubble size which implies there is a compelling relationship between these two, represented by C_Froth/C_Bulk and D₃₂. The C_Froth/C_Bulk and D₃₂ curves show similar exponential decay relationships as a function of added frother in the system, strongly suggesting that the frother concentration gradient between the bulk solution and the bubble interface is the driving force contributing to bubble size reduction.

The properties of circulating gas have a significant effect on sintering with flue gas recirculation, and the influence of CO in sintering process was investigated. The results show that the post-combustion of CO conducts in sinter zone when flue gas passes through the sintering bed, which releases much heat and reduces the consumption of solid fuel. The ratio of coke breeze can be reduced from 5% to 4.7% with 2% CO in circulating flue gas. In addition, with the increase of CO content in circulating flue gas, the combustion efficiency of fuel is improved, and the flame front is increased slightly while still matches with the heat transfer front. These are beneficial to increasing the maximum temperature and prolonging the high temperature duration, especially in the upper layer of sintering bed. As a consequence, the productivity, vertical sintering velocity and quality of sinter are improved.

The main principle and mathematical model of GOCE kinematic orbit adjustment for Earth gravity field model (EGM) validation and accelerometer calibration are presented. Based on 60 days GOCE kinematic orbits with 1–2 cm accuracy and accelerometer data from 2009-11-02 to 2009-12-31, the RMS-of-fit (ROF) of them using EGM2008, EIGEN-5C, ITG-GRACE2010S and GOCO01S up to 120, 150 and 180 degree and order (d/o) are evaluated and compared. The scale factors and biases of GOCE accelerometer data are calibrated and the energy balance method (EBM) is performed to test the accuracy of accelerometer calibration. The results show that GOCE orbits are also sensitive to EGM from 120 to 150 d/o. The ROFs of EGMs with 150 and 180 d/o are obviously better than those of EGMs with 120 d/o. The ROFs of GOCO01S and ITG-GRACE2010S are almost the same up to 120 and 150 d/o, which are about 3.3 cm and 1.8 cm, respectively. They are far better than those of EGM2008 and EIGEN-5C with the same d/o. The ROF of GOCO01S with 180 d/o is about 1.6 cm, which is the best one among those EGMs. The accelerometer calibration accuracies (ACAs) of ITG-GRACE2010S and GOCO01S are obviously higher that those of EGM2008 and EIGEN-5C. The ACA of GOCO01S with 180 d/o is far higher than that of EGMs with 120 d/o, and a little higher than that of ITG-GRACE2010S with 150 d/o. It is suggested that the newest released EGM such as GOCO01S or GOCO02S till at least 150 d/o should be chosen in GOCE precise orbit determination (POD) and accelerometer calibration.

The mechanism of cracks propagation and cracks coalescence due to compressive loading of the brittle substances containing pre-existing cracks (flaws) was modeled experimentally using specially made rock-like specimens from Portland Pozzolana Cement (PPC). The breakage process of the specimens was studied by inserting single and double flaws with different inclination angles at the center and applying uniaxial compressive stress at both ends of the specimen. The first crack was oriented at 50° from the horizontal direction and kept constant throughout the analysis while the orientation of the second crack was changed. It is experimentally observed that the wing cracks are produced at the first stage of loading and start their propagation toward the direction of uniaxial compressive loading. The secondary cracks may also be produced in form of quasi-coplanar and/or oblique cracks in a stable manner. The secondary cracks may eventually continue their propagation in the direction of maximum principle stress. These experimental works were also simulated numerically by a modified higher order displacement discontinuity method and the cracks propagation and cracks coalescence were studied based on Mode I and Mode II stress intensity factors (SIFs). It is concluded that the wing cracks initiation stresses for the specimens change from 11.3 to 14.1 MPa in the case of numerical simulations and from 7.3 to 13.8 MPa in the case of experimental works. It is observed that cracks coalescence stresses change from 21.8 to 25.3 MPa and from 19.5 to 21.8 MPa in the numerical and experimental analyses, respectively. Comparing some of the numerical and experimental results with those recently cited in the literature validates the results obtained by the proposed study. Finally, a numerical simulation was accomplished to study the effect of confining pressure on the crack propagation process, showing that the SIFs increase and the crack initiation angles change in this case.

The process and characteristics of loading on high-speed railway bridge pile foundation were firstly obtained by means of field research and analysis, and the corresponding loading function was presented. One-dimensional consolidation equation of elastic multilayered soils was then established with single drainage or double drainages under multilevel loading. Moreover, the formulas for calculating effective stress and settlement were derived from the Laplace numerical inversion transform. The three-dimensional composite analysis method of bridge pile group was improved, where the actual load conditions of pile foundation could be simulated, and the consolidation characteristics of soil layers beneath pile were also taken into account. Eventually, a corresponding program named LTPGS was developed to improve the calculation efficiency. The comparison between long-term settlement obtained from the proposed method and the in-situ measurements of pile foundation was illustrated, and a close agreement is obtained. The error between computed and measured results is less than 1 mm, and it gradually reduces with time. It is shown that the proposed method can effectively simulate the long-term settlement of pile foundation and program LTPGS can provide a reliable estimation.

The vehicle-track-bridge (VTB) element was used to investigate how a high-speed railway bridge reacted when it was subjected to near-fault directivity pulse-like ground motions. Based on the PEER NAG Strong Ground Motion Database, the spatial analysis model of a vehicle-bridge system was developed, the VTB element was derived to simulate the interaction of train and bridge, and the elasto-plastic seismic responses of the bridge were calculated. The calculation results show that girder and pier top displacement, and bending moment of the pier base increase subjected to near-fault directivity pulse-like ground motion compared to far-field earthquakes, and the greater deformation responses in near-fault shaking are associated with fewer reversed cycles of loading. The hysteretic characteristics of the pier subjected to a near-fault directivity pulse-like earthquake should be explicitly expressed as the bending moment-rotation relationship of the pier base, which is characterized by the centrally strengthened hysteretic cycles at some point of the loading time-history curve. The results show that there is an amplification of the vertical deflection in the girder’s mid-span owing to the high vertical ground motion. In light of these findings, the effect of the vertical ground motion should be used to adjust the unconservative amplification constant 2/3 of the vertical-to-horizontal peak ground motion ratio in the seismic design of bridge.

The dynamic responses of the arch dam including dam-foundation-storage capacity of water system, using two different earthquake input models, i.e. viscous-spring artificial boundary (AB) condition and massless foundation (MF), were studied and analyzed for the 269 m high Baihetan arch dam under construction in China. By using different input models, the stress and opening of contraction joints (OCJs) of arch dam under strong shock were taken into consideration. The results show that the earthquake input models have slight influence on the responses including earthquake stresses and openings of contraction joints in different extents.

An essential step for the realization of free-form surface structures is to create an efficient structural gird that satisfies not only the architectural aesthetics, but also the structural performance. Employing the main stress trajectories as the representation of force flows on a free-form surface, an automatic grid generation approach is proposed for the architectural design. The algorithm automatically plots the main stress trajectories on a 3D free-form surface, and adopts a modified advancing front meshing technique to generate the structural grid. Based on the proposed algorithm, an automatic grid generator named “St-Surmesh” is developed for the practical architectural design of free-form surface structure. The surface geometry of one of the Sun Valleys in Expo Axis for the Expo Shanghai 2010 is selected as a numerical example for validating the proposed approach. Comparative studies are performed to demonstrate how different structural grids affect the design of a free-form surface structure.

Variations between earthquakes result in many factors that influence post-earthquake building damage (e.g., ground motion parameters, building structure, site information, and quality of construction). Consequently, it is necessary to develop an appropriate building damage-rate estimation model. The building damage survey data were recorded and constructed into files by the Architecture and Building Research Institute (ABRI), Taiwan for the 1999 Chi-Chi earthquake in the Nantou region as a basis for developing a building damage rate estimation model by applying fuzzy theory to express the fragility curves of buildings as a membership function. Empirical verification was performed using post-earthquake building damage data in the Taichung city that suffered relatively severe damage. Results indicate that fuzzy theory can be applied to predict building damage rates and that the estimated results are similar to actual disaster figures. Prediction of disaster damage using building damage rates can provide a reference for immediate disaster response during earthquakes and for regular disaster prevention and rescue planning.

Based on a simplified 3-DOF model of twin-tower structure linked by a sky-bridge, the frequency response functions, the displacement power spectral density (PSD) functions, and the time-averaged total vibration energy were derived, by assuming the white noise as the earthquake excitation. The effects of connecting parameters, such as linking stiffness ratio and linking damping ratio, on the structural vibration responses were then studied, and the optimal connecting parameters were obtained to minimize the vibration energy of either the independent monomer tower or the integral structure. The influences of sky-bridge elevation position on the optimal connecting parameters were also discussed. Finally, the distribution characteristics of the top displacement PSD and the structural responses, excited by El Centro, Taft and artificial waves, were compared in both frequency and time domain. It is found that the connecting parameters at either end of connection interactively affect the responses of the towers. The optimal connecting parameters can greatly improve the damping connections on their seismic reduction effectiveness, but are unable to reduce the seismic responses of the towers to the best extent simultaneously. It is also indicated that the optimal connecting parameters derived from the simplified 3-DOF model are applicable for two multi-story structures linked by a sky-bridge with dampers. The seismic reduction effectiveness obtained varies from 0.3 to 1.0 with different sky-bridge mass ratio. The displacement responses of the example structures are reduced by approximately 22% with sky-bridge connections.

By using large scale triaxial shearing apparatus, consolidated-drained shear tests were conducted on coarse-grained soil with different gradations. In order to describe their deformation rules, three main characteristics of tangent Poisson ratio curves were summarized and the reason was revealed by dividing the movement of soil particles into two kinds: the movement of fine particles and the movement of coarse particles. Then, a volumetric strain expression and a tangent Poisson ratio expression were put forward, and two defects of widely used Duncan-Chang model were fixed. Results calculated from them agree well with test results. There are three parameters, namely L, G and F, in this new model. Parameter L reflects the dilatancy of a specimen and L=4 can be used as a criterion to estimate whether a certain kind of soil has dilatancy quality or not. Parameters G and F relate to the initial slope of tangent Poisson ratio curves, and G=F=0 indicates a special situation which happens in dense granular material of the same diameter. Influences of various gradations on volume deformation are mainly reflected in parameter L which is smaller when there are more gravels in specimens.

The determination of collapse margin ratio (CMR) of structure is influenced by many uncertain factors. Some factors that can affect the calculation of CMR, e.g., the elongation of the structural fundamental period prior to collapse, the determination of earthquake intensity measure, the seismic hazard probability, and the difference of the spectral shapes between the median spectrum of the ground motions and the design spectrum, were discussed. Considering the elongation of the structural fundamental period, the intensity measure S_a(T₁) should be replaced with S_a* in the calculation of CMR for short-period and medium-period structures. The reasonable intensity measure should be determined by the correlation analysis between the earthquake intensity measure and the damage index of the structure. Otherwise, CMR should be adjusted according to the seismic hazard probability and the difference in the spectral shapes. For important long-period structures, CMR should be determined by the special site spectrum. The results indicate that both S_a(T₁) and spectrum intensity (SI) could be used as intensity measures in the calculation of CMR for medium-period structures, but SI would be a better choice for long-period structures. Moreover, an adjusted CMR that reflects the actual seismic collapse safety of structures is provided.

The uncertainties of some key influence factors on coal crushing, such as rock strength, pore pressure and magnitude and orientation of three principal stresses, can lead to the uncertainty of coal crushing and make it very difficult to predict coal crushing under the condition of in-situ reservoir. To account for the uncertainty involved in coal crushing, a deterministic prediction model of coal crushing under the condition of in-situ reservoir was established based on Hoek-Brown criterion. Through this model, key influence factors on coal crushing were selected as random variables and the corresponding probability density functions were determined by combining experiment data and Latin Hypercube method. Then, to analyze the uncertainty of coal crushing, the first-order second-moment method and the presented model were combined to address the failure probability involved in coal crushing analysis. Using the presented method, the failure probabilities of coal crushing were analyzed for WS5-5 well in Ningwu basin, China, and the relations between failure probability and the influence factors were furthermore discussed. The results show that the failure probabilities of WS5-5 CBM well vary from 0.6 to 1.0; moreover, for the coal seam section at depth of 784.3–785 m, the failure probabilities are equal to 1, which fit well with experiment results; the failure probability of coal crushing presents nonlinear growth relationships with the increase of principal stress difference and the decrease of uniaxial compressive strength.

The basic head shape of high-speed train is determined by its longitudinal type-line (LTL), so it is crucial to optimize its aerodynamic performance. Based on the parametric modeling of LTL constructed by non-uniform relational B-spline (NURBS) and the fluctuation pressure obtained by large eddy simulation (LES), the Kriging surrogate model (KSM) of LTL was constructed for low aerodynamic noise, and the accuracy of the KSM was improved gradually by adding the sample point with maximum expected improvement (EI) and the optimal point from optimization. The optimal objective was searched with genetic algorithm (GA). The results show that the total fluctuation pressure level (FPL) of the optimal LTL can be 8.7 dB less than that of original one, and the shape optimization method is feasible for low aerodynamic noise design.

Unmanned aerial vehicle (UAV) was introduced to take road segment traffic surveillance. Considering the limited UAV maximum flight distance, UAV route planning problem was studied. First, a multi-objective optimization model of planning UAV route for road segment surveillance was proposed, which aimed to minimize UAV cruise distance and minimize the number of UAVs used. Then, an evolutionary algorithm based on Pareto optimality technique was proposed to solve multi-objective UAV route planning problem. At last, a UAV flight experiment was conducted to test UAV route planning effect, and a case with three scenarios was studied to analyze the impact of different road segment lengths on UAV route planning. The case results show that the optimized cruise distance and the number of UAVs used decrease by an average of 38.43% and 33.33%, respectively. Additionally, shortening or extending the length of road segments has different impacts on UAV route planning.

With the wide applications of sensor network technology in traffic information acquisition systems, a new measure will be quite necessary to evaluate spatially related properties of traffic information credibility. The heterogeneity of spatial distribution of information credibility from sensor networks is analyzed and a new measure, information credibility function (ICF), is proposed to describe this heterogeneity. Three possible functional forms of sensor ICF and their corresponding expressions are presented. Then, two feasible operations of spatial superposition of sensor ICFs are discussed. Finally, a numerical example is introduced to show the calibration method of sensor ICF and obtain the spatially related properties of expressway in Beijing. The results show that the sensor ICF of expressway in Beijing possesses a negative exponent property. The traffic information is more abundant at or near the locations of sensor, while with the distance away from the sensor increasing, the traffic information credibility will be declined by an exponential trend. The new measure provides theoretical bases for the optimal locations of traffic sensor networks and the mechanism research of spatial distribution of traffic information credibility.

A good understanding of pedestrian movement in the transfer corridor is vital for the planning and design of the station, especially for efficiency and safety. A multi-force vector grid model was presented to simulate the movement of bidirectional pedestrian flow based on cellular automata and forces between pedestrians. The model improves rule-based characteristics of cellular automata, details forces between pedestrians and solves pedestrian collisions by a several-step updating method to simulate pedestrian movements. Two general scenarios in corridor were simulated. One is bidirectional pedestrian flow simulation with isolation facility, and the other is bidirectional pedestrian flow simulation without isolation facility, where there exists disturbance in the middle. Through simulation, some facts can be seen that pedestrians in the case with isolation facility have the largest speed and pedestrians in the case without isolation facility have the smallest speed; pedestrians in the case of unidirectional flow have the largest volume and pedestrians in the case of without isolation facility have the smallest volume.

A control strategy of variable speed limits (VSL) was developed to reduce the travel time at freeway recurrent bottleneck areas. The proposed control strategy particularly focused on preventing the capacity drop and increasing the discharge flow. A cell transmission model (CTM) was developed to evaluate the effects of the proposed VSL control strategy on the traffic operations. The results show that the total travel time is reduced by 25.5% and the delay is reduced by 56.1%. The average travel speed is increased by 34.3% and the queue length is reduced by 31.0%. The traffic operation is improved by the proposed VSL control strategy. The way to use the proposed VSL control strategy in different types of freeway bottlenecks was also discussed by considering different traffic flow characteristics. It is concluded that the VSL control strategy is effective for merge bottlenecks but is less effective for diverge bottlenecks.

In order to optimize the crashworthy characteristic of energy-absorbing structures, the surrogate models of specific energy absorption (SEA) and ratio of SEA to initial peak force (REAF) with respect to the design parameters were respectively constructed based on surrogate model optimization methods (polynomial response surface method (PRSM) and Kriging method (KM)). Firstly, the sample data were prepared through the design of experiment (DOE). Then, the test data models were set up based on the theory of surrogate model, and the data samples were trained to obtain the response relationship between the SEA & REAF and design parameters. At last, the structure optimal parameters were obtained by visual analysis and genetic algorithm (GA). The results indicate that the KM, where the local interpolation method is used in Gauss correlation function, has the highest fitting accuracy and the structure optimal parameters are obtained as: the SEA of 29.8558 kJ/kg (corresponding to a=70 mm and t= 3.5 mm) and REAF of 0.2896 (corresponding to a=70 mm and t=1.9615 mm). The basis function of the quartic PRSM with higher order than that of the quadratic PRSM, and the mutual influence of the design variables are considered, so the fitting accuracy of the quartic PRSM is higher than that of the quadratic PRSM.

Based on the parametric analysis of the expanding zone of the vacuum dust suction mouth, the flow in the vacuum dust suction mouth was simulated by computational fluid dynamics (CFD) software, Fluent. The effects of the expanding zone parameters on flow simulation were analyzed. The results show that simulation effects depend on threshold values of the expanding zone parameters of the dust suction mouth, and the threshold values of the expanding zone can be obtained according to the different structures of the vacuum dust suction mouth and be selected as the geometric parameters in calculating, and also corners of the expanding zone make unobvious difference in calculation accuracy and in computational efficiency compared with no corner. The simulation results provide practical guidance to the flow simulation on the dust suction mouth.