Pure Cu nanowires as catalyst were prepared by electrochemical deposition and were used in CO₂ hydrogenation to methanol. The active sites of the Cu based catalyst were discussed. The performance and structural development of the catalyst were observed during CO₂ hydrogenation. A mechanism for the deactivation of the catalyst was discussed. The key factors that affect the deactivation of the catalyst were found. Cu nanowire sample was characterized by SEM, EDS, XRD, and BET. The results show that Cu nanowires have very high sintering resistance and catalytic stability. This helps to develop high performance catalysts. The changes in the grain size, SEM morphology and catalytic properties of the sample during CO₂ hydrogenation show that the migration of the Cu atoms on the surface of the Cu nanowires can occur. Continuous migration of Cu atoms and sintering of Cu grains can lead to flow blockage in gas channels. The gas channel flow blockage or the sintering of Cu grains can lead to deactivation of the catalyst. However, the shape of catalytic performance curve indicates that the main reason for the deactivation of the catalyst is the gas channel flow blockage.

For the determination of salicylaldoxime in environmental water samples, a stable and rapid method with low detection was proposed and established, based on the liquid-liquid extraction-high performance liquid chromatography with ultraviolet detector. Parameters including extraction solvent, ionic strength, solution pH, and extraction pattern were discussed for the optimal quantification of salicylaldoxime-spiked water. When the described method was applied to four spiked water samples, the obtained average extraction recovery rate was found between 87%–107% and relative standard deviation was below 6%. At the same time, good linear relationships were observed for spiked water samples from 0.01 to 10 μg/mL (R²=0.9993). In addition, the detection limit of salicylaldoxime was revealed between 0.003–0.008 μg/mL, which is two orders of magnitude lower than previously reported results. Thus, the presented method may be advantageous for the high-efficiency determination of salicylaldoxime in water samples.

The purpose of this study is to explore the adsorption performance of meso-2, 3-dimercaptosuccinic acid (DMSA) modified Fe3O4@SiO2 magnetic nanocomposite (Fe₃O₄@SiO₂DMSA) for Pb²⁺ ions removal from aqueous solutions. The effects of solution pH, initial concentration of Pb2+ions, contact time, and temperature on the amount of Pb2+ adsorbed were investigated. Adsorption isotherms, adsorption kinetics, and thermodynamic analysis were also studied. The results showed that the maximum adsorption capacity of the Fe₃O₄@SiO₂DMSA composite is 50.5 mg/g at 298 K, which is higher than that of Fe3O4 and Fe₃O₄@SiO₂ magnetic nanoparticles. The adsorption process agreed well with Langmuir adsorption isotherm models and pseudo second-order kinetics. The thermodynamic analysis revealed that the adsorption was spontaneous, endothermic and energetically driven in nature.

Lithium metal is one of the most promising anode materials for rechargeable battery with high energy density, but its practical use is still hindered by two main problems, namely, lithium dendrite growth and low Coulombic efficiency. To address the issues, cesium nitrate (CsNO₃) is selected as the additive to modify the electrolyte for lithium secondary battery. Here we report electrochemical performance of lithium secondary battery with different concentration of CsNO₃ as electrolyte additive. The study result demonstrates that Coulombic efficiency of Li—Cu cells and the lifetime of symmetric lithium cells contained CsNO3 additive are improved greatly. Li—Cu cell with 0.05 mol/L CsNO₃ and 0.15 mol/L LiNO₃ as electrolyte additive presents the best electrochemical performance, having the highest Coulombic efficiency of around 97% and the lowest interfacial resistance. With increasing the concentration of CsNO₃ as electrolyte additive, the electrochemical performance of cells becomes poor. Meanwhile, the morphology of lithium deposited films with CsNO₃-modified electrolyte become smoother and more uniform compared with the basic electrolyte.

In order to expand the application of the basic magnesium carbonate in the field of flame retardant, the plate-like basic magnesium carbonate (Mg₅(CO₃)₄(OH)₂.4H₂O) was prepared successfully by template-mediated/ homogeneous precipitation method, using magnesium chloride hexahydrate (MgCl₂.6H₂O) and urea (CO(NH₂)₂) as reaction materials. Phase and morphology of the product were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and atomic force microscope (AFM), respectively. The results showed that well-crystallized plate-like Mg₅(CO₃)₄(OH)₂.4H₂O can be prepared at the water bath temperature of 100 °C, water bath time of 24 h, the aging time of 5 h after adding organic template agent. The investigation on organic template mediated mechanism shows that the template affects the crystal morphology by changing surface energy of different crystal plane. Through a preliminary study on the growth mechanism of the product, it is found that the generation of the plate-like Mg₅(CO₃)₄(OH)₂.4H₂O could be explained by two-dimensional nucleation/step growth mechanism.

The influences of hot stamping parameters such as heating temperature, soaking time, deformation temperature and cooling medium on the phase transformation, microstructure and mechanical properties of 30MnB5 and 22MnB5 are investigated and analyzed in this work. The quenching experiment, tensile testing, hardness measurement and microstructure observation were conducted to obtain the mechanical and microstructural data. The results indicate that 30MnB5 possesses a higher tensile strength but a lower elongation than 22MnB5, if hot stamped at the same process parameter. The tensile strength and hardness of the hot stamped specimens decrease under inappropriate heating conditions for two reasons, insufficient austenitization or coarse austenite grains. The austenitic forming rate of 30MnB5 is higher than that of 22MnB5, because more cementite leads to higher nucleation rate and diffusion coefficient of carbon atom. More amount of fine martensite forms under the higher deformation temperature or the quicker cooling rate.

In order to estimate deformation and mechanical properties of material accurately, elastic and plastic deformation behavior of small punch test was discussed in this paper. A two-dimensional finite element model was established based upon the Gurson-Tvergaard-Needleman(GTN) equation. According to the integration of load—displacement curves with different displacements, the evolution of elastic energy was obtained. The results show that the elastic energy increases quickly in the initial region and tends to be an approximate constant during the plastic bending phase. Meanwhile, an obvious change of the slope of load—displacement curve can be found in the elastic-plastic transition region. The macroscopic deformation and fracture feature were also discussed in order to verify the deformation analysis. Finally, the yield strength, tensile strength and elongation of AISI304 were obtained based on the analysis of deformation energy and percent fracture deflection. The results have a good agreement with that of conventional tensile tests, which may provide a theoretical basis of small punch analysis.

Effects of nickel component, thiourea, glue and chloride ions and their interactions on the passivation of copper—nickel based alloy scrap anodes were investigated by combining conventional electrochemical techniques. Results obtained from chronopotentiometry and linear voltammetry curves showed that the Ni component made electrochemical stability of the anode strong and difficult to be corroded, caused by the adsorption of generated Cu₂O, NiO or copper powder to the anode surface. The Ni²⁺ reducing Cu²⁺ to Cu⁺ or copper powder aggravated the anode passivation. In a certain range of the glue concentration ≤8×10^-6 or thiourea concentration ≤4×10^-6, the increase of glue or thiourea concentration increases the anode passivation time. Over this range, glue and thiourea played an adverse effect. The increase of chloride ions concentration led to the increase in passivation time.

Mg-8Li-3Al-0.7Si alloy was prepared by casting and deformed by hot extrusion in this study. And the microstructure of as-cast and extruded specimens was analyzed with OM, XRD, SEM and EDS. Results show that the specimens are composed of α-Mg, β-Li, AlLi, MgLiAl₂ and Mg₂Si phases. In as-extruded specimen, the microstructure is refined and the β-Li phase has the effect of coordination during deformation. After hot extrusion, Chinese script Mg₂Si phase is crushed into block-like and distributes uniformly in the matrix. Mechanical properties results show that the strength and elongation are both improved after hot extrusion.

Structural and electronic properties of Pb_nAg_n (n=2–12) clusters were investigated by density functional theory with generalized gradient approximation at BLYP level in DMol³ program package. The optimized bimetallic Pb_nAg_n (n=2–12) clusters were viewed as the initial structures, then, those were calculated by ab initio molecular dynamics (AIMD) to search possible global minimum energy structures of Pb_nAg_n clusters, finally, the ground state structures of Pb_nAg_n (n=2–12) clusters were achieved. According to the structural evolution of lowest energy structures, Ag atoms prefer gather in the central sites while Pb atoms prefer external positions in Pb_nAg_n (n=2–12) clusters, which is in excellent agreement with experimental results from literature and the application in metallurgy. The average binding energies, HOMO-LUMO gaps, vertical ionization potentials, vertical electron affinities, chemical hardness η, HOMO orbits, LUMO orbits and density of states of Pb_nAg_n (n=2–12) clusters were calculated. The results indicate that the values of HOMO-LUMO gaps, vertical ionization potentials, vertical electron affinities and chemical hardness η show obvious odd-even oscillations when n≤5, Pb_nAg_n (n=2–12) clusters become less chemically stable and show insulator-to-metal transition with the variation of cluster size n, Pb_nAg_n (n≥9) cluster are good candidates to study the properties of PbAg alloys. Those can be well explained by the density of states (DOS) distributions of Pb atoms and Ag atoms between–0.5 Ha and 0.25 Ha in Pb_nAg_n (n=2–12) clusters.

In the present paper, the fundamental research on the properties of boron-rich slag melting separated from boron-bearing iron concentrate was performed. The melting and fluidity of B₂O₃-MgO-SiO₂-FeO slag system, crystallization of separated boron-rich slag and factors on the extraction efficiency of boron-rich slag were systematically investigated. B₂O₃ content would heavily affect the melting and fluidity property of boron-rich slag. Generally, FeO could improve the melting and fluidity property of boron-rich slag. Boron-containing crystalline phase mainly precipitated in temperature range from 1200 °C to 1100 °C. Higher smelting temperature and B2O3 reduction ratio were negative for the extraction of boron. The cooling rate of 10–20 °C/min was better for the crystallization of boron-containing crystalline phase. Based on the obtained experimental results, the optimum operating parameters for the development of pyrometallurgical boron and iron separation process and further boron-rich slag cooling process were proposed.

Grinding is one of the most costly operations in the mechanical breaking and mining. Determination of the breakage characteristics and preconditioning is important to increase the grinding efficiency. Investigations of the seismic, mechanical and breakage properties of iron oxides are very important parameters for investigating the rock fragmentation by blasting and comminution processes in iron ore mines. In this paper, at first, geomechanical and seismic properties of the oxide ores (magnetite and hematite) in the Chadormalu iron ore mine were studied. The results showed that the percentage of magnetite has a direct relationship with uniaxial compressive strength, tensile strength and P and S wave’s velocities and has an inverse relationship with Poisson ratio and porosity. Moreover, to study breakage and preconditioning characteristics in the iron ores, two samples with different magnetite percents were blasted by detonation cord. The results showed that with higher percentage of magnetite, the number of fractures induced by blasting increased. Bond work index and magnetite percent were investigated in the 430 blasts in the mine. This investigation not only confirmed the small scale blasting results, but also showed that increasing the magnetite percent up to 50% noticeably reduces Bond work index and energy consumption in the grinding process. Also, the relationship between muck pile fragmentation and magnetite percentage were studied for several blasts that had the same blast pattern parameters and similar geology conditions. These results also confirmed precedents conclusions regarding magnetite percent and preconditioning relationship.

In this study, the effects of surfactants on the hydrodynamic characteristics of bubbles in shear-thinning fluids at low Reynolds number (Re<50) are investigated. The bubble terminal velocity and drag coefficient of bubble in clean and contaminated carboxymethylcellulose (CMC) solutions are obtained using a high-speed camera for examining differences. The results show that the existence of surfactant could reduce the terminal velocity of bubble at small volume (0.25wt% CMC: <100 mm³; 0.50wt% CMC: <110 mm³), attributed to stiffening the bubble interface. However, this negative effect decreases and finally disappears with increasing bubble volume. The drag coefficient curves of the bubble in contaminated CMC solution exhibit behavior similar to that exhibited by a solid sphere at Re<10, indicating that internal circulation flow is absent at the bubble interface as compared to that in clean CMC solution. However, for 10<Re<40, a transition of drag curve from 24/Re to 16/Re in contaminated CMC solution is observed, which is easy at low SDS concentrations and high CMC concentrations.

Studies to date have failed to consider gage disc cutters’ variable cutting depth and the constraints of cutter-head welds, and have ignored the coupling mechanism between the profile of the full-face rock tunnel-boring machine (TBM) cutter-head and the assembled radius layout of the disc cutters. To solve these problems, an adaptive design method for studying cutter layout was proposed. Taking the bearing stress of the outermost gage disc cutter as an index, the profile of the cutter-head was determined. Using a genetic algorithm and based on the principles of equal life and equal wear, the assembled radii of the cutters were optimally designed. Boundary conditions of non-interference between the cutters, manholes, muck buckets and welding lines were given when a star layout pattern was used on cutters. The cutter-head comprehensive evaluation model was established by adopting relative optimization improvement degree of evaluation indices to achieve dimensional consistency. Exemplifying the MB264-311-8030 mm tape TBM cutter-head, the calculations show that compared with the original layout scheme, among the 51 disc cutters, the largest gap of the cutters’ assembled radiuses is only 25.8 mm, which is 0.64% of the cutter-head’s radius and is negligible. The cutter-head’s unbalanced radial force decreases by 62.41%, the overturning moment decreases by 33.22%, and the cutter group’s centroid shift increases by only 18.48%. Each index is better than or approximately equal to the original cutter-head layout scheme, and the equivalent stress and deformation are both smaller; these results fully verify the feasibility and effectiveness of the method.

Aiming at the issue of sliding ratio, an internal gear pair is proposed which consists of an involute internal gear and a pinion with quadratic curve teeth. Particularly, the contact pattern is point contact and the pinion is generated based on an involute gear. The generation method and mathematical models of the gear pair are presented. The sliding ratio is calculated and the general calculation formulas of sliding ratios are developed. Also, the comparison between the involute gear and proposed gear is made. The adaptability of center distance and contact stress are also discussed. In addition, the gear pair was manufactured and inspected according to the exactitude solid model of the gear pair. In order to confirm this model to be effective, the efficiency experiment and the contrast experiment with the involute gear pair were performed. Furthermore, these two types of pinions were analyzed by scanning electron microscope and wear depths were measured by measuring center. The experiment results show that the efficiency of the internal gear pair is stable at a range about 97.1% to 98.6% and wear depth is less than 50% of the involute gear pair. The internal gear pair is expected to have excellent transmission performance.

Geological adaptability matching design of a disc cutter is the prerequisite of cutter head design for tunnel boring machines (TBMs) and plays an important role in improving the tunneling efficiency of TBMs. The main purpose of the cutter matching design is to evaluate the cutter performance and select the appropriate cutter size. In this paper, a novel evaluation method based on multicriteria decision making (MCDM) techniques was developed to help TBM designers in the process of determining the cutter size. The analytic hierarchy process (AHP) and matter element analysis were applied to obtaining the weights of the cutter evaluation criteria, and the fuzzy comprehensive evaluation and technique for order performance by similarity to ideal solution (TOPSIS) approaches were employed to determine the ranking of the cutters. A case application was offered to illustrate and validate the proposed method. The results of the project case demonstrate that this method is reasonable and feasible for disc cutter size selection in cutter head design.

Based on the biological prototype characteristics of shark’s gill jet orifice, the flexible driving characteristics of ionic exchange polymer metal composites (IPMC) artificial muscle materials and the use of sleeve flexible connector, the IPMC linear driving unit simulation model is built and the IPMC material-driving dynamic control structure of bionic gill unit is developed. Meanwhile, through the stress analysis of bionic gill plate and the motion simulation of bionic gill unit, it is verified that various dynamic control and active control of the jet orifice under the condition of different mainstream field velocities will be taken by using IPMC material-driving. Moreover, the large-deflection deformation of bionic gill plate under dynamic pressure and the comparative analysis with that of a rigid gill plate is studied, leading to the achievement of approximate revised modifier from real value to theoretical value of the displacement control of IPMC.

Stone column is one of the soil stabilizing methods that is used to increase bearing capacity and decrease the settlement of soft soils. Reinforced and unreinforced granular blankets are now being utilized to overcome the problems of soft soils. In this research, the bearing capacity of stone columns, granular blanket, and a combination of both methods in reinforced and unreinforced modes were studied using scaled physical models. Results show that using granular blanket, stone column, and combination of both improves bearing capacity of soft soils. Using geogrid as the reinforcement of granular blankets and geotextile as stone-column encasement increases the efficiency of granular blankets and stone columns significantly. Additionally, in the case of using geotextile around the stone column, the stress concentration ratio of the stone column will increase as well as its rigidity and bearing capacity.

Due to the disturbances arising from the coherence of reflected waves and from echo noise, problems such as limitations, instability and poor accuracy exist with the current quantitative analysis methods. According to the intrinsic features of GPR signals and wavelet time—frequency analysis, an optimal wavelet basis named GPR3.3 wavelet is constructed via an improved biorthogonal wavelet construction method to quantitatively analyse the GPR signal. A new quantitative analysis method based on the biorthogonal wavelet (the QAGBW method) is proposed and applied in the analysis of analogue and measured signals. The results show that compared with the Bayesian frequency-domain blind deconvolution and with existing wavelet bases, the QAGBW method based on optimal wavelet can limit the disturbance from factors such as the coherence of reflected waves and echo noise, improve the quantitative analytical precision of the GPR signal, and match the minimum thickness for quantitative analysis with the vertical resolution of GPR detection.

Predicting high-quality volcanic reservoirs is one of the key issues for oil and gas exploration in the Songnan gas field. Core, seismic, and measurement data were used to study the lithologies, facies, reservoir porosity, and reservoir types of the volcanic rocks in the Songnan gas field. The primary controlling factors and characteristics of the high-quality volcanic reservoirs of the Yingcheng Formation in the Songnan gas field were investigated, including the volcanic eruptive stage, edifice, edifice facies, cooling unit, lithology, facies, and diagenesis. Stages with more volatile content can form more high-quality reservoirs. The effusive rhyolite, explosive tuff, and tuff lava that formed in the crater, near-crater, and proximal facies and in the high-volatility cooling units of large acidic-lava volcanic edifices are the most favorable locations for the development of the high-quality reservoirs in the Songnan gas field. Diagenesis dissolution, which is controlled by tectonic action, can increase the size of secondary pores in reservoirs. Studying the controlling factors of the high-quality reservoirs can provide a theoretical basis for the prediction and analysis of high-quality volcanic reservoirs.

This paper presents a bi-level hybrid local search (BHLS) algorithm for the three-dimensional loading problem with balancing constraints (3DLP-B), where several rectangular boxes with even densities but different sizes are loaded into a single cubic bin to meet the requirements of the space or capacity utilization and the balance of the center of gravity. The proposed algorithm hybridizes a novel framed-layout procedure in which the concept of the core block and its generation strategy are introduced. Once the block-loading sequence has been determined, we can load one block at a time by the designed construction heuristic. Then, the double-search is introduced; its external search procedure generates a list of compact packing patterns while its internal search procedure is used to search the core-block frames and their best distribution locations. The approach is extensively tested on weakly to strongly heterogeneous benchmark data. The results show that it has better performance in improving space utilization rate and balanced condition of the placement than existed techniques: the overall averages from 79.85% to 86.45% were obtained for the balanced cases and relatively high space-usage rate of 89.44% was achieved for the unbalanced ones.

Accurate 3-D fracture network model for rock mass in dam foundation is of vital importance for stability, grouting and seepage analysis of dam foundation. With the aim of reducing deviation between fracture network model and measured data, a 3-D fracture network dynamic modeling method based on error analysis was proposed. Firstly, errors of four fracture volume density estimation methods (proposed by ODA, KULATILAKE, MAULDON, and SONG) and that of four fracture size estimation methods (proposed by EINSTEIN, SONG and TONON) were respectively compared, and the optimal methods were determined. Additionally, error index representing the deviation between fracture network model and measured data was established with integrated use of fractal dimension and relative absolute error (RAE). On this basis, the downhill simplex method was used to build the dynamic modeling method, which takes the minimum of error index as objective function and dynamically adjusts the fracture density and size parameters to correct the error index. Finally, the 3-D fracture network model could be obtained which meets the requirements. The proposed method was applied for 3-D fractures simulation in Miao Wei hydropower project in China for feasibility verification and the error index reduced from 2.618 to 0.337.

To ensure running safety, the secondary spring loads of railway vehicles must be well equalized. Due to the coupling interactive effects of these hyper static suspended structures, the equalization adjustment through shimming procedure is quite complex. Therefore, an effective and reliable method in application is developed in this paper. Firstly, the best regulation of spring load is solved based on a mechanical model of the secondary suspension system, providing a target for actual adjustment. To reveal the relationship between secondary spring load distribution and shim quantity sequence, a forecasting model is constructed and then modified experimentally with consideration of car body’s elastic deformation. Further, a gradient-based algorithm with a momentum operation is proposed for the load optimization. Effectiveness of the whole method has been verified on a test rig. It is experimentally confirmed that this research provides an important basis for achieving an optimal regulation of spring load distribution for multiple types of railway vehicles.

Limit analysis of the stability of geomechanical projects is one of the most difficult problems. This work investigates the influences of different parameters in NL failure strength on possible collapsing block shapes of single and twin shallow tunnels with considering the effects of surface settlement. Upper bound solutions derived by functional catastrophe theory are used for describing the distinct characteristics of falling blocks of different parts in twin tunnels. Furthermore the analytical solutions of minimum supporting pressures in shallow tunnels are obtained by the help of the variational principle. Lastly, the comparisons are made both in collapsed mechanism and stability factor with different methods. According to the numerical results in this work, the influences of different parameters on the size of collapsing block are presented in the tables and the limit supporting loads are illustrated in the form graphs that account for the surface settlement.