The single crystal of nickel-base super alloy is widely used for making turbine blades. The microstructure of the alloy, especially the deviation of preferred orientation of single crystal, possesses the most important effects on the mechanical properties of the blades. In this study, the single crystal ingot and blade of DZ417G alloy are prepared by means of the spiral crystal selector as well as the directional solidification method, and the effect of the parameters (i.e., the shape of samples, the withdrawal rate) and the structure of the spiral crystal selector on the formation of single crystal and the crystal orientation are investigated. This method can prepare not only the single crystal ingot with simple shape but also the single crystal blades with the complex shape, the simple with rod-shape can form the single crystal easily with a relatively fast withdrawal rate, but the blade with complex shape requires much slower withdrawal rate to form single crystal. The length of the crystal selector almost has no effect on the crystal orientation. However, the angle of selector plays an obvious role on the orientation; the selector with a smaller angle can effectively reduce the deviation of preferred orientation; the appropriate angle of selector to obtain optimal orientation is found to be around 30°and the deviation of preferred orientation is about 30° for this selector.

A novel microwave digestion and alkali fusion assisted hydrothermal method was proposed to synthesize zeolite from coal fly ash and the zeolite product was studied for removal of Cd(II) from aqueous solution through batch experiments. The adsorbent was characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, surface area analyzer and zeta potential measurement. The results show that the synthetic zeolite was identified as faujasite. The optimum conditions for removal of Cd(II) are found to be: adsorbent dose of 0.5 g/L, pH 6, contact time of 90 min and initial concentration of 20 mg/L, the removal rate of Cd(II) is 98.55%. The experimental kinetic data agree well with the pseudo second-order equation; the Langmuir isotherm model is found to be more suitable to explicate the experimental equilibrium isotherm results than Freundlich, Dubinin-Radushkevich and Temkin models, and the maximum adsorption capacity of Cd(II) is found to be 86.96 mg/g. The thermodynamic parameters such as ΔG^Θ, ΔH^Θ and ΔS^Θ were evaluated and the results show that the adsorption of Cd(II) onto the as-synthesized zeolite is spontaneous, endothermic and feasible under studied conditions.

The addition of NaCl in the ammonium persulfate-APS (as an oxidant) leaching was investigated. APS has some advantages compared with conventional oxidants and its standard redox potential (E°) is 2.0 V. Effect of six parameters such as NaCl concentration, APS concentration, temperature, time, liquid–solid ration (L/S), and stirring speed on the leaching behavior was studied. Results showed that metals extraction increased with increasing of NaCl concentration, APS concentration, leaching temperature (up to 333 K), and L/S ratio. During oxidative leaching of sulfide minerals, the occurrence of elemental sulfur layer on particle surface is known as primary problem that causes low metal extraction. According to the results, the passivation effect of sulfur layer and low dissolution problems can be eliminated in the presence of chloride ions. Copper and iron extraction yields were obtained as 75% and 80%, respectively under leaching conditions as follows: APS concentration 250 g/L; NaCl concentration 150 g/L; time 180 min; temperature 333 K; stirring speed 400 r/min; and L/S 250 mL/g.

The separation of azodicarbonamide (AC) from the surface of diatomite by froth flotation is investigated in this research. Pure samples of diatomite, AC and 1:1 mixtures of the two were floated in a lab-scale flotation cell with collector dosage, frother type and dosage, and pH varied to determine the optimum experimental conditions. The diatomite sample and products from flotation tests were characterized using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDX). The results of the flotation tests indicate that there is less AC on the surface of diatomite after flotation compared to the feed, while the AC present in diatomite pores remains unchanged. Additionally, Fourier transform infrared spectroscopy (FT-IR) was employed to study the mechanism of interaction between reagents and minerals.

Three types of mine gas samples were used in the solutions of tetrahydrofuran (THF), sodium dodecyl sulfate (SDS) and THF-SDS with/without MMT respectively to investigate the effect of montmorillonite (MMT) on separation characteristics of methane recovered from mine gas based on hydrate method. The partition coefficient, separation factor and recovery rate were used to evaluate the effects of MMT, and the selection factor was primarily proposed to define the selectivity of mine gas hydrate in the relative target gases. The experimental results indicate that MMT could improve the following factors including hydration separation factor, the selection factor, the partition coefficient, and the recovery rate. Furthermore, the effect of SDS on the function of MMT is analyzed in the process of hydration separation. Finally, due to the results of the experiment, it is concluded that MMT hydration mechanism explores the effect of MMT enrichment methane from mine gas.

Partially replacing polyvinyl-alcohol (PVA) fibers with polypropylene (PP) fibers in strain-hardening cementitious composites (fiber hybridization) modify certain mechanical properties of these materials. The hybridization based on the introduction of low-modulus hydrophobic polypropylene fibers improves the ductility and the strain-hardening behavior of the cementitious composites containing polyvinyl-alcohol fibers of different types (PVA-SHCC). Pull-out tests indicate that adding PP fibers increases the energy capacity of the hybrid composite with respect to the material containing only PVA fibers under tensile loading, and PP-fiber geometry (i.e., section shape and length) is a key factor in enhancing the strain capacity.

In the process of thin-wall parts assembly for an antenna, the parts assembly deformation deviation is occurring due to the riveting assembly. In view of the riveting assembly deformation problems, it can be analyzed through transient and static simulation. In this work, the theoretical deformation model for riveting assembly is established with round head rivet. The simulation analysis for riveting deformation is carried out with the riveting assembly piece including four rivets, which comparing with the measuring points experiment results of riveting test piece through dealing with the experimental data using the point coordinate transform method and the space line fitting method. Simultaneously, the deformation deviation of the overall thin-wall parts assembly structure is analyzed through finite element simulation; and its results are verified by the measuring experiment for riveting assembly with the deformation deviation of some key points on the thin-wall parts. Through the comparison analysis, it is shown that the simulation results agree well with the experimental results, which proves the correctness and effectiveness of the theoretical analysis, simulation results and the given experiment data processing method. Through the study on the riveting assembly for thin-wall parts, it will provide a theoretical foundation for improving thin-wall parts assembly quality of large antenna in future.

This paper proposed the reclosing method in distribution system with battery energy storage system (BESS) using wavelet transform (WT). The proposed method performs the WT of load current and then calculates the absolute value of slope of detail coefficient. The mother wavelet used is db4 of level 6. The fault clearing is detected using the rapid increase of this value. After the detection of fault clearing, the reclosing is performed. To verify the proposed method, various simulations according to the fault clearing times, fault resistances, and fault lengths are performed using EMTP. The simulation results show that fault clearing can be detected using proposed absolute value of slope of detail coefficient and hence the reclosing can be performed successfully.

For anomaly detection, anomalies existing in the background will affect the detection performance. Accordingly, a background refinement method based on the local density is proposed to remove the anomalies from the background. In this work, the local density is measured by its spectral neighbors through a certain radius which is obtained by calculating the mean median of the distance matrix. Further, a two-step segmentation strategy is designed. The first segmentation step divides the original background into two subsets, a large subset composed by background pixels and a small subset containing both background pixels and anomalies. The second segmentation step employing Otsu method with an aim to obtain a discrimination threshold is conducted on the small subset. Then the pixels whose local densities are lower than the threshold are removed. Finally, to validate the effectiveness of the proposed method, it combines Reed-Xiaoli detector and collaborative-representation-based detector to detect anomalies. Experiments are conducted on two real hyperspectral datasets. Results show that the proposed method achieves better detection performance.

Considering the influence of reagent adjustment in different flotation bank on the final production index and the difficulty of establishing an effective mathematical model, a coordinated optimization method for dosage reagent based on key characteristics variation tendency and case-based reasoning is proposed. On the basis of the expert reagent regulation method in antimony flotation process, the reagent dosage pre-setting model of the roughing–scavenging bank is constructed based on case-based reasoning. Then, the sensitivity index is used to calculate the key features of reagent dosage. The reagent dosage compensation model is constructed based on the variation tendency of the key features in the roughing and scavenging process. At last, the prediction model is used to finish the classification and discriminant analysis. The simulation results and industrial experiment in antimony flotation process show that the proposed method reduces fluctuation of the tailings indicators and the cost of reagent dosage. It can lay a foundation for optimizing the whole process of flotation.

A modified artificial bee colony optimizer (MABC) is proposed for image segmentation by using a pool of optimal foraging strategies to balance the exploration and exploitation tradeoff. The main idea of MABC is to enrich artificial bee foraging behaviors by combining local search and comprehensive learning using multi-dimensional PSO-based equation. With comprehensive learning, the bees incorporate the information of global best solution into the solution search equation to improve the exploration while the local search enables the bees deeply exploit around the promising area, which provides a proper balance between exploration and exploitation. The experimental results on comparing the MABC to several successful EA and SI algorithms on a set of benchmarks demonstrated the effectiveness of the proposed algorithm. Furthermore, we applied the MABC algorithm to image segmentation problem. Experimental results verify the effectiveness of the proposed algorithm.

This work focuses on motion control of high-velocity autonomous underwater vehicle (AUV). Conventional methods are effective solutions to motion control of low-and-medium-velocity AUV. Usually not taken into consideration in the control model, the residual dead load and damping force which vary with the AUV’s velocity tend to result in difficulties in motion control or even failure in convergence in the case of high-velocity movement. With full consideration given to the influence of residual dead load and changing damping force upon AUV motion control, a novel sliding-mode controller (SMC) is proposed in this work. The stability analysis of the proposed controller is carried out on the basis of Lyapunov function. The sea trials results proved the superiority of the sliding-mode controller over sigmoid-function-based controller (SFC). The novel controller demonstrated its effectiveness by achieving admirable control results in the case of high-velocity movement.

A modeling tool for simulating three-dimensional land frequency-domain controlled-source electromagnetic surveys, based on a finite-element discretization of the Helmholtz equation for the electric fields, has been developed. The main difference between our modeling method and those previous works is edge finite-element approach applied to solving the three-dimensional land frequency-domain electromagnetic responses generated by horizontal electric dipole source. Firstly, the edge finite-element equation is formulated through the Galerkin method based on Helmholtz equation of the electric fields. Secondly, in order to check the validity of the modeling code, the numerical results are compared with the analytical solutions for a homogeneous half-space model. Finally, other three models are simulated with three-dimensional electromagnetic responses. The results indicate that the method can be applied for solving three-dimensional electromagnetic responses. The algorithm has been demonstrated, which can be effective to modeling the complex geo-electrical structures. This efficient algorithm will help to study the distribution laws of 3-D land frequency-domain controlled-source electromagnetic responses and to setup basis for research of three-dimensional inversion.

Based on Bingham rheological model, a three-dimensional numerical simulation model for long-distance pipeline transportation is established by computational fluid dynamics (CFD) to study the pipeline transportation properties of high sliming paste from a copper mine in China. Based on the rheological properties test, the pressure and velocity of pipeline and elbow are simulated by CFD under different mass concentrations and different stowing capacities. The results show that the pipeline resistance of whole-tailings paste with high sliming while without pumping agent is much higher than that with high sliming and pumping agent at the same mass concentration, and the pipeline resistance of whole-tailings paste with high sliming while without pumping agent is much higher than that with low sliming while without pumping agent. It is very important to add pumping agent to whole-tailings paste with high sliming, and the resistance changes with mass concentration and stowing capacity at the same cement-to-sand ratio of 1:5 and tailings-to-waste ratio of 6:1. However, the change is just limited, that is to say, the paste transportation system is of good stability. Furthermore, at the elbow, the maximum pressure and velocity transfer to the outside of the pipe from the inside. However, lubricating layer is formed at the pipe wall because of high content of fine particles in whole-tailings paste, which will protect the elbow from abrasion. CFD provides an intuitive and accurate basis for pipeline transportation study, and would have a wider application space in the study of paste rheological properties and resistance reduction methods.

There are few methods of semi-autogenous (SAG) mill power prediction in the full-scale without using long experiments. In this work, the effects of different operating parameters such as feed moisture, mass flowrate, mill load cell mass, SAG mill solid percentage, inlet and outlet water to the SAG mill and work index are studied. A total number of 185 full-scale SAG mill works are utilized to develop the artificial neural network (ANN) and the hybrid of ANN and genetic algorithm (GANN) models with relations of input and output data in the full-scale. The results show that the GANN model is more efficient than the ANN model in predicting SAG mill power. The sensitivity analysis was also performed to determine the most effective input parameters on SAG mill power. The sensitivity analysis of the GANN model shows that the work index, inlet water to the SAG mill, mill load cell weight, SAG mill solid percentage, mass flowrate and feed moisture have a direct relationship with mill power, while outlet water to the SAG mill has an inverse relationship with mill power. The results show that the GANN model could be useful to evaluate a good output to changes in input operation parameters.

Surface mining operations extract a large quantity of waste material, which is generally disposed into a dump area. This waste can cause a series of environmental problems ranging from landscape deterioration to acidic water generation and water pollution. Therefore, mine waste management is a significant task in mining operations. As known, in strip mining, the overburden is not transported to waste dumps but disposed directly into adjacent strip which was mined out. This concept can be adapted for mine planning of relatively horizontal deposits through a mixed integer programming (MIP) model. The main idea behind this work is that, in one pit, production voids created in early year of mining are used for waste landfilling in late years of production. In other words, in addition to external dumping, a landfilling option within the same pit is proposed for mine design optimization. The problem is formulated as maximization of the net present value (NPV) of the mining project under the constraints of access, landfill waste handling, mining and processing capacities. A case study using a data set was carried out to see the performance of the proposed approach. The findings showed that this approach could be used in waste management incorporating a landfilling option into mine planning. As a result, material handling costs decrease, and environmental compliance increases due to less external waste quantity.

By virtue of a complete set of two displacement potentials, an analytical derivation of the elastostatic Green’s functions of an exponentially graded transversely isotropic substrate–coating system is presented. Three-dimensional point–load and patch–load Green’s functions for stresses and displacements are given in line-integral representations. The formulation includes a complete set of transformed stress–potential and displacement–potential relations, with utilizing Fourier series and Hankel transforms. As illustrations, the present Green’s functions are degenerated to the special cases such as an exponentially graded half-space and a homogeneous two-layered half-space Green’s functions. Because of complicated integrand functions, the integrals are evaluated numerically and for numerical computation of the integrals, a robust and effective methodology is laid out which gives the necessary account of the presence of singularities of integration. Comparisons of the existing numerical solutions for homogeneous two-layered isotropic and transversely isotropic half-spaces are made to confirm the accuracy of the present solutions. Some typical numerical examples are also given to show the general features of the exponentially graded two-layered half-space Green’s functions that the effect of degree of variation of material properties will be recognized.

A 3D finite element model (FEM) with realistic field measurements of temperature distributions is proposed to investigate the thermal stress variation in the steel–concrete composite bridge deck system. First, a brief literature review indicates that traditional thermal stress calculation in suspension bridges is based on the 2D plane structure with simplified temperature profiles on bridges. Thus, a 3D FEM is proposed for accurate stress analysis. The focus is on the incorporation of full field arbitrary temperature profile for the stress analysis. Following this, the effect of realistic temperature distribution on the structure is investigated in detail and an example using field measurements of Aizhai Bridge is integrated with the proposed 3D FEM model. Parametric studies are used to illustrate the effect of different parameters on the thermal stress distribution in the bridge structure. Next, the discussion and comparison of the proposed methodology and simplified calculation method in the standard is given. The calculation difference and their potential impact on the structure are shown in detail. Finally, some conclusions and recommendations for future bridge analysis and design are given based on the proposed study.

A method of analyzing the stability of twin shallow tunnels was presented using both limit analysis with nonlinear failure criterion and reliability theory. In the condition of nonlinear failure criterion, the critical clear distances of twin shallow tunnels were obtained by analyzing the change of surrounding pressure. A reliability model was established based on limit state equation, and the failure probability was solved by virtue of Monte Carlo method. Safety factor and corresponding clear distance of different safety levels were obtained by introducing a target reliability index. The scope of clear distance for different safety levels is described, which can be used as a supplement and improvement to the design codes of tunnels.

A forward recursive formulation based on corotational frame is proposed for flexible planar beams with large displacement. The traditional recursive formulation has been successfully used for flexible mutibody dynamics to improve the computational efficiency based on floating frame, in which the assumption of small strain and deflection is adopted. The proposed recursive formulation could be used for large displacement problems based on the corotational frame. It means that the recursive scheme is used not only for adjacent bodies but also for adjacent beam elements. The nodal relative rotation coordinates of the planar beam are used to obtain equations with minimal generalized coordinates in present formulation. The proposed formulation is different from absolute nodal coordinate formulation and the geometrically exact beam formulation in which the absolute coordinates are used. The recursive scheme and minimal set of dynamic equations lead to a high computational efficiency in numerical integration. Numerical examples are carried out to demonstrate the accuracy and validity of this formulation. For all of the examples, the results of the present formulation are in good agreement with results obtained using commercial software and the published results. Moreover, it is shown that the present formulation is more efficient than the formulation in ANSYS based on GEBF.

Reservoir impoundment is related to several hydraulic engineering concerns, including irreversible valley contractions, landslides and reservoir-induced earthquakes. However, these phenomena, such as valley contractions, are hardly to be explained by the conventional method. The scientific understanding of water effects during impoundment and their hazards to hydraulic structure are needed. The effective stress law for fissured rock masses is introduced in the elasto-plastic model employing the Drucker-Prager criterion and implemented in the three dimension (3D) nonlinear finite element method (FEM) program Three-dimensional FINite Element (TFINE). The slope deforms towards river-way during impoundment since the increasing pore pressure in fissures changes stress state and leads to additional plastic deformation in the rock materials. The value of Biot coefficient and the influence of water on rock materials are discussed in detail. Thus, the mechanism of slope deformation during the impoundment of Jinping-I arch dam is revealed, and the deformation is accurately measured. The application of the effective stress law provides a method to consider stress assessment, deformation evaluation and stability estimate of hydraulic structures during the impoundment process. This is a beneficial exploration and an improvement of hydraulic engineering design.

Non-uniform rational B-spline (NURBS) curves are combined with the Kriging model to present a prediction method of the rail grinding profile for a grinding train. As a worn rail profile is a free-form curve, the parameterized model of a rail profile is constructed by using the cubic NURBS curve. Taking the removed area of the rail profile cross-section by grinding as the calculation index of the grinding amount, the grinding amount calculation model of a grinding wheel is established based on the area integral formula of the cubic NURBS curve. To predict the grinding amount of a grinding wheel in different modes, a Kriging model of the grinding amount is constructed, taking the travel speed of a grinding train, the grinding angle and grinding pressure of a grinding wheel as the variables, and considering the grinding amount of a grinding wheel as the response. On this basis, the prediction method of the rail grinding profile is presented based on the order-forming mechanisms. The effectiveness of this method is verified based on a practical application.

The goal of this paper is to find an excellent adaptive window function for extracting the weak vibration signal and high frequency vibration signal under strong noise. The relationship between windowing transform and filtering is analyzed first in the paper. The advantage of adjustable time-frequency window of wavelet transform is introduced. Secondly the relationship between harmonic wavelet and multiple analytic band-pass filter is analyzed. The coherence of the multiple analytic band-pass filter and harmonic wavelet base function is discussed, and the characteristic that multiple analytic band-pass filter included in the harmonic wavelet transform is founded. Thirdly, by extending the harmonic wavelet transform, the concept of the adaptive harmonic window and its theoretical equation without decomposition are put forward in this paper. Then comparing with the Hanning window, the good performance of restraining side-lobe leakage possessed by adaptive harmonic window is shown, and the adaptive characteristics of window width changing and analytical center moving of the adaptive harmonic window are presented. Finally, the proposed adaptive harmonic window is applied to weak signal extraction and high frequency orbit extraction of high speed rotor under strong noise, and the satisfactory results are achieved. The application results show that the adaptive harmonic window function can be successfully applied to the actual engineering signal processing.