scispace - formally typeset
Search or ask a question

Showing papers in "Journal of Central South University in 2014"


Journal ArticleDOI
TL;DR: In this paper, a semi-analytical method called differential transformation method (DTM) was used for solving the nonlinear temperature distribution equation in solid and porous longitudinal fin with temperature dependent internal heat generation.
Abstract: A simple and highly accurate semi-analytical method, called the differential transformation method (DTM), was used for solving the nonlinear temperature distribution equation in solid and porous longitudinal fin with temperature dependent internal heat generation. The problem was solved for two main cases. In the first case, heat generation was assumed variable by fin temperature for a solid fin and in second heat generation varied with temperature for a porous fin. Results are presented for the temperature distribution for a range of values of parameters appearing in the mathematical formulation (e.g. N, ɛ G , and G). Results reveal that DTM is very effective and convenient. Also, it is found that this method can achieve more suitable results in comparison to numerical methods.

91 citations


Journal ArticleDOI
TL;DR: In this article, the peristaltic transport of viscous fluid in an asymmetric channel is concentrated, and numerical integration for pressure rise per wavelength is carried out for pressure increase per wavelength.
Abstract: The peristaltic transport of viscous fluid in an asymmetric channel is concentrated. The channel walls exhibit convective boundary conditions. Both cases of hydrodynamic and magnetohydrodynamic (MHD) fluids are considered. Mathematical analysis has been presented in a wave frame of reference. The resulting problems are non-dimensionalized. Long wavelength and low Reynolds number approximations are employed. Joule heating effect on the thermal equation is retained. Analytic solutions for stream function and temperature are constructed. Numerical integration is carried out for pressure rise per wavelength. Effects of influential flow parameters have been pointed out through graphs.

48 citations


Journal ArticleDOI
TL;DR: In this paper, the magnetohydrodynamic (MHD) three-dimensional flow of Jeffrey fluid in the presence of Newtonian heating is investigated and series solutions are constructed for the velocity and temperature fields.
Abstract: The magnetohydrodynamic (MHD) three-dimensional flow of Jeffrey fluid in the presence of Newtonian heating is investigated. Flow is caused by a bidirectional stretching surface. Series solutions are constructed for the velocity and temperature fields. Convergence of series solutions is ensured graphically and numerically. The variations of key parameters on the physical quantities are shown and discussed in detail. Constructed series solutions are compared with the existing solutions in the limiting case and an excellent agreement is noticed. Nusselt numbers are computed with and without magnetic fields. It is observed that the Nusselt number decreases in the presence of magnetic field.

48 citations


Journal ArticleDOI
TL;DR: Based on the axial stress-axial strain curves, the effect of fissure angle on the strength and deformation behavior of sandstone specimens containing combined flaws is analyzed in this paper.
Abstract: Based on the axial stress-axial strain curves, the effect of fissure angle on the strength and deformation behavior of sandstone specimens containing combined flaws is analyzed. The mechanical parameters of sandstone specimens containing combined flaws are all lower than that of intact specimen, but the reduction extent is distinctly related to the fissure angle. The results of sandstone specimens containing combined flaws are obtained by the acoustic emission, which can be used to monitor the crack initiation and propagation. The ultimate failure mode and crack coalescence behavior are evaluated for brittle sandstone specimens containing combined flaws. Nine different crack types are identified on the basis of their geometry and crack coalescence mechanism (tensile crack, hole collapse, far-field crack and surface spalling) for combined flaws. The photographic monitoring was also adopted for uniaxial compression test in order to confirm the sequence of crack coalescence in brittle sandstone specimens containing combined flaws, which recorded the real-time crack coalescence process during entire deformation. According to the monitored results, the effect of crack coalescence process on the strength and deformation behavior is investigated based on a detailed analysis for brittle sandstone specimens containing combined flaws by using digital photogrammetry.

40 citations


Journal ArticleDOI
TL;DR: In this paper, a mathematical model was built to analyze the relationship between power outputs and pitch angle, and an optimized pitch angle along the rotor was presented, and a considerable improvement was obtained by the optimized blade pitch angle in particular, a relative increase of the power coefficient by more than 19.3%.
Abstract: Wind energy is one of the most promising renewable energy sources, straight-bladed vertical axis wind turbine (S-VAWT) appears to be particularly promising for the shortage of fossil fuel reserves owing to its distinct advantages, but suffers from poor self-starting and low power coefficient. Variable-pitch method was recognized as an attractive solution to performance improvement, thus majority efforts had been devoted into blade pitch angle effect on aerodynamic performance. Taken into account the local flow field of S-VAWT, mathematical model was built to analyze the relationship between power outputs and pitch angle. Numerical simulations on static and dynamic performances of blade were carried out and optimized pitch angle along the rotor were presented. Comparative analyses of fixed pitch and variable-pitch S-VAWT were conducted, and a considerable improvement of the performance was obtained by the optimized blade pitch angle, in particular, a relative increase of the power coefficient by more than 19.3%. It is further demonstrated that the self-starting is greatly improved with the optimized blade pitch angle.

39 citations


Journal ArticleDOI
TL;DR: An evolutionary algorithm based on Pareto optimality technique was proposed to solve multi-objective UAV route planning problem and shows that the optimized cruise distance and the number of UAVs used decrease.
Abstract: 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.

38 citations


Journal ArticleDOI
TL;DR: In this paper, a quantificational formula between the value of rock burst proneness index and the accumulative acoustic emission counts in rock sample under uniaxial compression with axial strain increases is developed.
Abstract: Rock burst is a severe disaster in mining and underground engineering, and it is important to predict the rock burst risk for minimizing the loss during the constructing process. The rock burst proneness was connected with the acoustic emission (AE) parameter in this work, which contributes to predicting the rock burst risk using AE technique. Primarily, a rock burst proneness index is proposed, and it just depends on the heterogeneous degree of rock material. Then, the quantificational formula between the value of rock burst proneness index and the accumulative AE counts in rock sample under uniaxial compression with axial strain increases is developed. Finally, three kinds of rock samples, i.e., granite, limestone and sandstone are tested about variation of the accumulative AE counts under uniaxial compression, and the test data are fitted well with the theoretic formula.

37 citations


Journal ArticleDOI
TL;DR: A novel identification method of rock and soil parameters for vibration drilling based on the fuzzy least squares-support vector machine was developed, in which the fuzzy membership function was set by using linear distance and its parameters were optimized by using adaptive genetic algorithm.
Abstract: A single freedom degree model of drilling bit-rock was established according to the vibration mechanism and its dynamic characteristics. Moreover, a novel identification method of rock and soil parameters for vibration drilling based on the fuzzy least squares (FLS)-support vector machine (SVM) was developed, in which the fuzzy membership function was set by using linear distance, and its parameters, such as penalty factor and kernel parameter, were optimized by using adaptive genetic algorithm. And FLS-SVM identification on rock and soil parameters for vibration drilling was made by changing the input/output data from single freedom degree model of drilling bit-rock. The results of identification simulation and resonance column experiment show that relative error of natural frequency for some hard sand from identification simulation and resonance column experiment is 1.1% and the identification precision based on the fuzzy least squares-support vector machine is high.

36 citations


Journal ArticleDOI
Jianhua Chen1, Xian-hao Long1, Cui-hua Zhao1, Duan Kang1, Jin Guo1 
TL;DR: In this article, the relaxation and electronic properties of sulfide minerals surfaces (MoS2, Sb2S3, Cu2S, ZnS, PbS and FeS2) were investigated in the presence of H2O molecule.
Abstract: First-principles calculations are performed to investigate the relaxation and electronic properties of sulfide minerals surfaces (MoS2, Sb2S3, Cu2S, ZnS, PbS and FeS2) in presence of H2O molecule. The calculated results show that the structure and electronic properties of sulfide minerals surfaces have been influenced in presence of H2O molecule. The adsorption of the flotation reagent at the interface of mineral-water would be different from that of mineral surface due to the changes of surface structures and electronic properties caused by H2O molecule. Hence, the influence of H2O molecule on the reaction of flotation reagent with sulfide mineral surface will attract more attention.

36 citations


Journal ArticleDOI
TL;DR: In this article, the energy method is introduced to deduce the analytical solution which is suitable for the global buckling modes of idealized subsea pipeline and analyze the relationship between the critical buckling temperature, buckling length and amplitude under different high-order global lateral bucking modes.
Abstract: In order to avoid the curing effects of paraffin on the transport process and reduce the transport difficulty, usually high temperature and high pressure are used in the transportation of oil and gas The differences of temperature and pressure cause additional stress along the pipeline, due to the constraint of the foundation soil, the additional stress can not release freely, when the additional stress is large enough to motivate the submarine pipelines buckle In this work, the energy method is introduced to deduce the analytical solution which is suitable for the global buckling modes of idealized subsea pipeline and analyze the relationship between the critical buckling temperature, buckling length and amplitude under different high-order global lateral buckling modes To obtain a consistent formulation of the problem, the principles of virtual displacements and the variation calculus for variable matching points are applied The finite element method based on elasto-plastic theory is used to simulate the lateral global buckling of the pipelines under high temperature and pressure The factors influencing the lateral buckling of pipelines are further studied Based upon some actual engineering projects, the finite element results are compared with the analytical ones, and then the influence of thermal stress, the section rigidity of pipeline, the soil properties and the trigging force to the high order lateral buckling are discussed The method of applying the small trigging force on pipeline is reliable in global buckling numerical analysis In practice, increasing the section rigidity of a pipeline is an effective measure to improve the ability to resist the global buckling

35 citations


Journal ArticleDOI
TL;DR: In this article, the application of optimal maintenance process was investigated for minimizing the equipment breakdowns and downtimes in Sungun Copper Mine, where 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.
Abstract: 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.

Journal ArticleDOI
TL;DR: In this paper, the grown conditions of acidithiobacillus ferrooxidans and acidity of acidity-thiooxidants were investigated, and then experiments were conducted to investigate the bio-leaching behaviors of crude ore of copper sulfide and hand-picked concentrates of chalcopyrite by acidiobactrinous bacteria.
Abstract: The grown conditions of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were investigated, and then experiments were conducted to research the bioleaching behaviors of crude ore of copper sulfide and hand-picked concentrates of chalcopyrite by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. The experimental results show that the bacteria grow best when the temperature is (30±1) °C and the pH value is 2.0. The bacteria concentration is 2.24×107 mL−1 in this condition. It is found that the copper extraction yield is affected by the inoculum size and the pulp density and the extraction yield increases as the inoculum size grows. The bioleaching rates reach their highest point in sulfide copper and chalcopyrite with a pulp density of 5% and 10%, respectively. Column flotation experiments of low-grade copper sulfide ores show that the bioleaching recovery reaches nearly 45% after 75 days.

Journal ArticleDOI
TL;DR: In this paper, the effect of various effective dimensionless numbers and moisture contents on initiation of instability in combustion of moisty organic dust is calculated, and a new expression is obtained by solving these newly achieved governing equations and combining them, which is completely discussed in body of article.
Abstract: In this work, the effect of various effective dimensionless numbers and moisture contents on initiation of instability in combustion of moisty organic dust is calculated. To have reliable model, effect of thermal radiation is taken into account. One-dimensional flame structure is divided into three zones: preheat zone, reaction zone and post-flame zone. To investigate pulsating characteristics of flame, governing equations are rewritten in dimensionless space-time (ξ, η, τ) coordinates. By solving these newly achieved governing equations and combining them, which is completely discussed in body of article, a new expression is obtained. By solving this equation, it is possible to predict initiation of instability in organic dust flame. According to the obtained results by increasing Lewis number, threshold of instability happens sooner. On the other hand, pulsating is postponed by increasing Damkohler number, pyrolysis temperature or moisture content. Also, by considering thermal radiation effect, burning velocity predicted by our model is closer to experimental results.

Journal ArticleDOI
TL;DR: 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).
Abstract: 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.

Journal ArticleDOI
TL;DR: In this paper, the adsorption of sulfate in aqueous solutions onto organo-nano-clay prepared by natural zeolite and cationic surfactant cetyltrimethylammonium bromide (CTAB) was studied.
Abstract: The adsorption of sulfate in aqueous solutions onto organo-nano-clay prepared by natural zeolite and cationic surfactant cetyltrimethylammonium bromide (CTAB) was studied. Parameters such as adsorbent dosage, contact time and temperature were investigated using batch adsorption studies. The results show that the uptake of sulfate increases with the increase of contact time and temperature, and decreases with the increase of dosage. The Freundlich isotherm model is fit to explain the sulfate adsorption onto organo-nano-clay. The maximum adsorption capacity is found to be 38.02 mg/g at 40 °C. The kinetic data fit well the pseudo-second-order and Elovich models with a R 2 more than 0.98. It is suggested that chemisorption is the rate-controlling step for adsorption of sulfate onto organo-nano-clay, meanwhile both intraparticle diffusion and boundary layer diffusion also contribute as well. Ion-exchange between sulfate anions and bromide ions and complexation between sulfate anions and CTAB cations are responsible for the mechanism of sulfate adsorption.

Journal ArticleDOI
TL;DR: In this article, a 1-dimensional (1-D) longitudinal model is proposed for estimating the dissipation coefficient of supersaturated total dissolved gas (TDG) downstream of a high-dam spill.
Abstract: The elevated supersaturation of total dissolved gas (TDG) downstream of a high-dam spill has deleterious effects on fish in a large range. A one-dimensional (1-D) longitudinal model is optimal for the prediction of supersaturated TDG dissipation over a long distance. The key issue of the model is to determine the dissipation coefficient accurately. In agreement with field observations and experiment data, dimensional analysis and regression were performed to propose a formula for estimating the dissipation coefficient of supersaturated TDG in various rivers and reservoirs, and it involves the effects of the turbulence intensity, the hydro-pressure and the solid-liquid interface. The friction velocity, water depth, hydraulic radius and Froude number are independent variables in the formula which are easy to determine in practical applications. The 1-D longitudinal model is implemented to calculate the dissipation of TDG in a reach of the Jinsha River. Good agreement is found between the calculated results and field data for both the dissipation coefficient and the dissipation process.

Journal ArticleDOI
TL;DR: In this paper, the effects of pH, contact time, adsorbent dosage and initial concentration of Cu(II) on the adsorbing abilities of CS, CS/RGO10 and CS/GO10 to Cu (II) were investigated.
Abstract: Cross-linked chitosan(CS), cross-linked chitosan/graphene(CS/RGO10) and cross-linked chitosan/graphene oxide(CS/GO10) were prepared as adsorbents for Cu(II). The effects of pH, contact time, adsorbent dosage and initial concentration of Cu(II) on the adsorbing abilities of CS,CS/RGO10 and CS/GO10 to Cu(II) were investigated. The results demonstrate that the adsorption capacities of CS/GO10 and CS/RGO10 are greater than that of CS, especially at pH 5.0 and the adsorption capacities are 202.5, 150 and 137.5 mg/g, respectively. Their behaviors obey the Freundlich isotherm model very well. Additionally, CS/GO10 has the shortest time to achieve adsorption equilibrium among them and can be used as a perspective adsorbent for Cu(II).

Journal ArticleDOI
TL;DR: In this paper, an approximate analytical RUL distribution in a closed-form of a nonlinear Wiener based degradation process with measurement errors was proposed, and the maximum likelihood estimation approach was used to estimate the unknown fixed parameters in the proposed model.
Abstract: Real time remaining useful life (RUL) prediction based on condition monitoring is an essential part in condition based maintenance (CBM). In the current methods about the real time RUL prediction of the nonlinear degradation process, the measurement error is not considered and forecasting uncertainty is large. Therefore, an approximate analytical RUL distribution in a closed-form of a nonlinear Wiener based degradation process with measurement errors was proposed. The maximum likelihood estimation approach was used to estimate the unknown fixed parameters in the proposed model. When the newly observed data are available, the random parameter is updated by the Bayesian method to make the estimation adapt to the item’s individual characteristic and reduce the uncertainty of the estimation. The simulation results show that considering measurement errors in the degradation process can significantly improve the accuracy of real time RUL prediction.

Journal ArticleDOI
TL;DR: In this paper, the suitability of equivalent rock mass (ERM) technique based upon particle methods is investigated by comparing calculated and experimental data of lab triaxial compression test on cylindrical rock mass samples, each containing a single joint oriented in various dip angles.
Abstract: Methods that can efficiently model the effects of rock joints on rock mass behavior can be beneficial in rock engineering. The suitability of equivalent rock mass (ERM) technique based upon particle methods is investigated. The ERM methodology is first validated by comparing calculated and experimental data of lab triaxial compression test on a set of cylindrical rock mass samples, each containing a single joint oriented in various dip angles. The simulated results are then used to study the stress-strain nonlinearity and failure mechanism as a function of the joint dip angle and confining stress. The anisotropy and size effects are also investigated by using multi-scale cubic ERM models subjected to triaxial compression test. The deformation and failure behavior are found to be influenced by joint degradation, the micro-crack formation in the intact rock, the interaction between two joints, and the interactions of micro-cracks and joints.

Journal ArticleDOI
Wen-bo Ma1, Qiu-hua Rao1, Peng Li1, Shuaicheng Guo1, Kang Feng1 
TL;DR: In this article, four kinds of simulative soils were prepared by mixing different bentonites with water in order to find the best simulative soil for the deep-sea sediment collected from the Pacific C-C area.
Abstract: Based on mineral component and in-situ vane shear strength of deep-sea sediment, four kinds of simulative soils were prepared by mixing different bentonites with water in order to find the best simulative soil for the deep-sea sediment collected from the Pacific C-C area. Shear creep characteristics of the simulative soil were studied by shear creep test and shear creep parameters were determined by Burgers creep model. Research results show that the shear creep curves of the simulative soil can be divided into transient creep, unstable creep and stable creep, where the unstable creep stage is very short due to its high water content. The shear creep parameters increase with compressive stress and change slightly or fluctuate to approach a constant value with shear stress, and thus average creep parameters under the same compressive stress are used as the creep parameters of the simulative soil. Traction of the deep-sea mining machine walking at a constant velocity can be calculated by the shear creep constitutive equation of the deep-sea simulative soil, which provides a theoretical basis for safe operation and optimal design of the deep-sea mining machine.

Journal ArticleDOI
TL;DR: In this article, surface functionalized silica nanoparticles were characterized by Fourier transform infrared (FI-IR) and X-ray photoelectron spectroscopy (XPS) for selective adsorption about Pb2+, Cu2+, Hg2+, Cd2+ and Zn2+ ions in aqueous solutions.
Abstract: The industrial silica fume pretreated by nitric acid at 80 °C was re-used in this work. Then, the obtained silica nanoparticles were surface functionalized by silane coupling agents, such as (3-Mercaptopropyl) triethoxysilane (MPTES) and (3-Amincpropyl) trithoxysilane (APTES). Some further modifications were studied by chloroaceetyl choride and 1,8-Diaminoaphalene for amino modified silica. The surface functionalized silica nanoparticles were characterized by Fourier transform infrared (FI-IR) and X-ray photoelectron spectroscopy (XPS). The prepared adsorbent of surface functionalized silica nanoparticles with differential function groups were investigated in the selective adsorption about Pb2+, Cu2+, Hg2+, Cd2+ and Zn2+ ions in aqueous solutions. The results show that the (3-Mercaptopropyl) triethoxysilane functionalized silica nanoparticles (SiO2-MPTES) play an important role in the selective adsorption of Cu2+ and Hg2+, the (3-Amincpropyl) trithoxysilane (APTES) functionalized silica nanoparticles (SiO2-APTES) exhibited maximum removal efficiency towards Pb2+ and Hg2+, the 1,8-Diaminoaphalene functionalized silica nanoparticles was excellent for removal of Hg2+ at room temperature, respectively.

Journal ArticleDOI
TL;DR: In this article, the heavy metal concentration, speciation, and pollution source in 43 sediment samples from the Xiangjiang River were investigated using sequential extraction combined with Pb isotope analysis.
Abstract: 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

Journal ArticleDOI
TL;DR: In this paper, a nonlinear state feedback controller was proposed based on backstepping technique and Lyapunov's direct method, which ensures that the solutions of closed loop system have the ultimate boundedness property.
Abstract: The trajectory planning and tracking control for an underactuated unmanned surface vessel (USV) were addressed. The reference trajectory was generated by a virtual USV, and the error equation of trajectory tracking for underactuated USV was obtained, which transformed the tracking and stabilization problem of underactuated USV into the stabilization problem of the trajectory tracking error equation. A nonlinear state feedback controller was proposed based on backstepping technique and Lyapunov’s direct method. By means of Lyapunov analysis, it is proved that the proposed controller ensures that the solutions of closed loop system have the ultimate boundedness property. Numerical simulation results are presented to validate the effectiveness and robustness of the proposed controller.

Journal ArticleDOI
TL;DR: In this article, the fly ash/H2O2 catalyst possesses a high oxidation activity for n-butyl xanthate degradation in aqueous solution, and it is found that both the dosage of catalyst and initial solution pH significantly affect the nbutyl Xanthate conversion efficient.
Abstract: Heterogeneous Fenton-like process using fly ash as a catalyst was studied to degrade n-butyl xanthate form aqueous solution. The different reaction parameters on the degradation efficiency of the process were investigated. The fly ash/H2O2 catalyst possesses a high oxidation activity for n-butyl xanthate degradation in aqueous solution. It is found that both the dosage of catalyst and initial solution pH significantly affect the n-butyl xanthate conversion efficient. The results indicate that by using 1.176 mmol/L H2O2 and 1.0 g/L fly ash catalyst with mass fraction of 4.14% Fe(III) oxide at pH 3.0, almost 96.90% n-butyl xanthate conversion and over 96.66% COD removal can be achieved within 120 min with heterogeneous catalysis by fly ash. CS2 as an intermediate of n-butyl xanthate oxidation. Finally, it is demonstrated that the fly ash/H2O2 catalytic oxidation process can be an efficient method for the treatment of n-butyl xanthate containing wastewater.

Journal ArticleDOI
TL;DR: In this article, three kinds of chelating agents were selected including citric acid, oxalic acid and ethylenediamine tetraaceatate (EDTA) to maintain available Fe2+.
Abstract: In the interest of accelerating aniline degradation, Fe2+ and chelated Fe2+ activated persulfate oxidations were investigated in neutral pH condition. Three kinds of chelating agents were selected including citric acid, oxalic acid and ethylenediamine tetraaceatate (EDTA) to maintain available Fe2+. The results indicate that the concentration of chelating agent and ferrous ion didn’t follow a linear relationship with the degradation rate of aniline. A 1/1 ratio of chelating agent/Fe2+ results in a higher degradation rate compared to the results by other ratios. The oxidation enhancement factor using oxalic acid was found to be relatively low. In contrast, citric acid is more suitable chelating agent in the ferrous iron activated persulfate system and aniline exhibits a highest degradation with a persulfate/Fe2+/citric acid/aniline molar ratio of 50/25/25/1 compared to other molar ratios.

Journal ArticleDOI
TL;DR: In this paper, a multi-stage triaxial compression test for cylindrical red sandstone specimens (diameter of 50 mm, height of 100 mm) with a rock mechanics testing system and spatial acoustic emission (AE) locations were obtained by adopting an AE monitoring system.
Abstract: Multi-stage triaxial compression tests for cylindrical red sandstone specimens (diameter of 50 mm, height of 100 mm) were carried out with a rock mechanics testing system and spatial acoustic emission (AE) locations were obtained by adopting an AE monitoring system. Based on spatial AE distribution evolution of red sandstone during multi-stage triaxial deformation, the relation between spatial AE events and triaxial deformation of red sandstone was analyzed. The results show that before peak strength, the spatial AE events are not active and distribute stochastically in the specimen, while after peak strength, the spatial AE events are very active and focus on a local region beyond final microscopic failure plane. During multi-stage triaxial deformation with five different confining pressures, the spatial AE distribution evolution in the red sandstone was obtained. The obtained spatial AE locations of red sandstone at the final confining pressure agree very well with the ultimate failure experimental mode. Finally, the influence of confining pressure on the spatial AE evolution characteristics of red sandstone during triaxial deformation was discussed. The AE behavior of red sandstone during multi-stage triaxial deformation is interpreted in the light of the Kaiser effect, which has a significant meaning for predicting the unstable failure of engineering rock mass.

Journal ArticleDOI
TL;DR: In this article, a reduced graphene oxide/Ni(OH)2 composite with excellent supercapacitive performance was synthesized by a facile hydrothermal route without organic solvents or templates used.
Abstract: A reduced graphene oxide/Ni(OH)2 composite with excellent supercapacitive performance was synthesized by a facile hydrothermal route without organic solvents or templates used. XRD and SEM results reveal that the nickel hydroxide, which crystallizes into hexagonal β-Ni(OH)2 nanoflakes with a diameter less than 200 nm and a thickness of about 10 nm, is well combined with the reduced graphene oxide sheets. Electrochemical performance of the synthesized composite as an electrode material was investigated by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge measurements. Its specific capacitance is determined to be 1672 F/g at a scan rate of 2 mV/s, and 696 F/g at a high scan rate of 50 mV/s. After 2000 cycles at a current density of 10 A/g, the composite exhibits a specific capacitance of 969 F/g, retaining about 86% of its initial capacitance. The composite delivers a high energy density of 83.6 W·h/kg at a power density of 1.0 kW/kg. The excellent supercapacitive performance along with the easy synthesis method allows the synthesized composite to be promising for supercapacitor applications.

Journal ArticleDOI
TL;DR: The proposed composition collision risk calculation method at ship’s position is implemented using combination of fuzzy and fuzzy comprehensive evaluation methods and is shown to be effective in automatic ship handling for ships involved in complex navigation situations.
Abstract: Despite of modern navigation devices, there are problems in navigation of vessels in waterways due to the geographical structures, disturbances in water, dynamic nature, and heavily environmental influenced sea traffic. Even though all vessels are equipped with modern navigation devices, the accidents are reported caused by various reasons and mainly by human factor according to investigation. We propose an effective and efficient composition collision risk calculation method for finding the collision probability and avoiding the collision between ships in possible collision situations. The proposed composition collision risk calculation method at ship’s position using combination of fuzzy and fuzzy comprehensive evaluation methods. The algorithm is straightforward to implement and is shown to be effective in automatic ship handling for ships involved in complex navigation situations. Experiments are carried out with indigenous data and the results show the effectiveness of the proposed approach.

Journal ArticleDOI
TL;DR: In this article, the temperature distributions of a prestressed concrete box girder bridge under the effect of cold wave processes were analyzed and a two-dimensional temperature gradient model was proposed and a parametric study that considered meteorological factors was performed.
Abstract: The temperature distributions of a prestressed concrete box girder bridge under the effect of cold wave processes were analyzed. The distributions were found different from those under the effect of solar radiation or nighttime radiation cooling and should not be simplified as one dimensional. A temperature predicting model that can accurately predict temperatures over the cross section of the concrete box girder was developed. On the basis of the analytical model, a two-dimensional temperature gradient model was proposed and a parametric study that considered meteorological factors was performed. The results of sensitivity analysis show that the cold wave with shorter duration and more severe temperature drop may cause more unfavorable influences on the concrete box girder bridge. Finally, the unrestrained linear curvatures, self-equilibrating stresses and bending stresses when considering the frame action of the cross section, were derived from the proposed temperature gradient model and current code provisions, respectively. Then, a comparison was made between the value calculated against proposed model and several current specifications. The results show that the cold wave may cause more unfavorable effect on the concrete box girder bridge, especially on the large concrete box girder bridge. Therefore, it is necessary to consider the thermal effect caused by cold wave during the design stage.

Journal ArticleDOI
TL;DR: In this paper, a new double reduction method, including a detailed calculation procedure and a definition of FOS for slope stability was developed based on the understanding of strength reduction method (SRM).
Abstract: The core of strength reduction method (SRM) involves finding a critical strength curve that happens to make the slope globally fail and a definition of factor of safety (FOS). A new double reduction method, including a detailed calculation procedure and a definition of FOS for slope stability was developed based on the understanding of SRM. When constructing the new definition of FOS, efforts were made to make sure that it has concise physical meanings and fully reflects the shear strength of the slope. Two examples, slopes A and B with the slope angles of 63° and 34° respectively, were given to verify the method presented. It is found that, for these two slopes, the FOSs from original strength reduction method are respectively 1.5% and 38% higher than those from double reduction method. It is also found that the double reduction method predicts a deeper potential slide line and a larger slide mass. These results show that on one hand, the double reduction method is comparative to the traditional methods and is reasonable, and on the other hand, the original strength reduction method may overestimate the safety of a slope. The method presented is advised to be considered as an additional option in the practical slope stability evaluations although more useful experience is required.