A Facile Li_(2)TiO_(3) Surface Modification to Improve the Structure Stability and Electrochemical Performance of Full Concentration Gradient Li-Rich Oxides

Full concentration gradient lithium-rich layered oxides are catching lots of interest as the next generation cathode for lithium-ion batteries due to their high discharge voltage,reduced voltage decay and enhanced rate performance,whereas the high lithium residues on its surface impairs the structure stability and long-term cycle performance.Herein,a facile multifunctional surface modification method is implemented to eliminate surface lithium residues of full concentration gradient lithium-rich layered oxides by a wet chemistry reaction with tetrabutyl titanate and the post-annealing process.It realizes not only a stable Li_(2)TiO_(3)coating layer with 3D diffusion channels for fast Li^(+)ions transfer,but also dopes partial Ti^(4+)ions into the sub-surface region of full concentration gradient lithium-rich layered oxides to further strengthen its crystal structure.Consequently,the modified full concentration gradient lithium-rich layered oxides exhibit improved structure stability,elevated thermal stability with decomposition temperature from 289.57℃to 321.72℃,and enhanced cycle performance(205.1 mAh g^(-1)after 150 cycles)with slowed voltage drop(1.67 mV per cycle).This work proposes a facile and integrated modification method to enhance the comprehensive performance of full concentration gradient lithium-rich layered oxides,which can facilitate its practical application for developing higher energy density lithium-ion batteries.

3D Printing of Tough Hydrogel Scaffolds with Functional Surface Structures for Tissue Regeneration

Hydrogel scaffolds have numerous potential applications in the tissue engineering field.However,tough hydrogel scaffolds implanted in vivo are seldom reported because it is difficult to balance biocompatibility and high mechanical properties.Inspired by Chinese ramen,we propose a universal fabricating method(printing-P,training-T,cross-linking-C,PTC&PCT)for tough hydrogel scaffolds to fill this gap.First,3D printing fabricates a hydrogel scaffold with desired structures(P).Then,the scaffold could have extraordinarily high mechanical properties and functional surface structure by cycle mechanical training with salting-out assistance(T).Finally,the training results are fixed by photo-cross-linking processing(C).The tough gelatin hydrogel scaffolds exhibit excellent tensile strength of 6.66 MPa(622-fold untreated)and have excellent biocompatibility.Furthermore,this scaffold possesses functional surface structures from nanometer to micron to millimeter,which can efficiently induce directional cell growth.Interestingly,this strategy can produce bionic human tissue with mechanical properties of 10 kPa-10 MPa by changing the type of salt,and many hydrogels,such as gelatin and silk,could be improved with PTC or PCT strategies.Animal experiments show that this scaffold can effectively promote the new generation of muscle fibers,blood vessels,and nerves within 4 weeks,prompting the rapid regeneration of large-volume muscle loss injuries.

Research status and prospects of the fractal analysis of metal material surfaces and interfaces

As a mathematical analysis method,fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties.Fractal analysis has been used to characterize the shapes of metal materials at various scales and dimensions.Conventional methods make it difficult to quantitatively describe the relationship between the regular characteristics and properties of metal material surfaces and interfaces.However,fractal analysis can be used to quantitatively describe the shape characteristics of metal materials and to establish the quantitative relationships between the shape characteristics and various properties of metal materials.From the perspective of two-dimensional planes and three-dimensional curved surfaces,this paper reviews the current research status of the fractal analysis of metal precipitate interfaces,metal grain boundary interfaces,metal-deposited film surfaces,metal fracture surfaces,metal machined surfaces,and metal wear surfaces.The relationship between the fractal dimensions and properties of metal material surfaces and interfaces is summarized.Starting from three perspectives of fractal analysis,namely,research scope,image acquisition methods,and calculation methods,this paper identifies the direction of research on fractal analysis of metal material surfaces and interfaces that need to be developed.It is believed that revealing the deep influence mechanism between the fractal dimensions and properties of metal material surfaces and interfaces will be the key research direction of the fractal analysis of metal materials in the future.

Exploitation technology of pressure relief coalbed methane in vertical surface wells in the Huainan coal mining area

Exploitation technology of pressure relief coalbed methane in vertical surface wells is a new method for exploration of gas and coalbed methane exploitation in mining areas with high concentrations of gas, where tectonic coal developed. Studies on vertical surface well technology in the Huainan Coal Mining area play a role in demonstration in the use of clean, new energy resources, preventing and reducing coal mine gas accidents and protecting the environment. Based on the practice of gas drainage engineering of pressure relief coalbed methane in vertical surface wells and combined with relative geological and exploration en- gineering theories, the design principles of design and structure of wells of pressure relief coalbed methane in vertical surface wells are studied. The effects of extraction and their causes are discussed and the impact of geological conditions on gas production of the vertical surface wells are analyzed. The results indicate that in mining areas with high concentrations of gas, where tectonic coal developed, a success rate of pressure relief coalbed methane in surface vertical well is high and single well production usually great. But deformation due to coal exploitation could damage boreholes and cause breaks in the connection between aquifers and bore-holes, which could induce a decrease, even a complete halt in gas production of a single well. The design of well site location and wellbore configuration are the key for technology. The development of the geological conditions for coalbed methane have a significant effect on gas production of coalbed methane wells.

Production Characteristics and the Control Factors of Surface Wells for Relieved Methane Drainage in the Huainan Mining Area

Based on the production data of a large number of surface drainage wells in the Huainan mining area,the present study shows that four types of typical production characteristics for relieved methane wells are recognized,of which the stable type for production and gas concentration is the most dominate,as determined by a comprehensive study on the volume and concentration of drained gases, as well as the stress changes of rocks influenced by mining.Some influence factors for the productive differences of the drainage wells were also been discussed.The results indicate that protective coal-seam mining has a significant effect on overlying strata,which promotes the development of pores and fractures of coal reservoirs for methane desorption and migration;however,the production and the stability of drainage wells are affected by deformation and damage of the overlying strata.The second distribution of strata stress is caused by mining engineering,and if the stress load is larger than the carrying capacity of the extraction well,the gas production would be influenced by the drainage well that has been damaged by rock movement.Furthermore,the case damage occurs first in the weak, lithologic interface by its special mechanical properties.The stability of drainage wells and the production status are also influenced by the different drilling techniques,uneven distribution of gas concentration,and combination of gob gas and methane from the protected layer.

Optimum location of surface wells for remote pressure relief coalbed methane drainage in mining areas

Based on engineering tests in the Huainan coal mining area,we studied alternative well location to improve the performance of surface wells for remote pressure relief of coalbed methane in mining areas.The key factors,affecting location and well gas production were analyzed by simulation tests for similar material.The exploitation results indicate that wells located in various positions on panels could achieve relatively better gas production in regions with thin Cenozoic layers,low mining heights and slow rate of longwall advancement,but their periods of gas production lasted less than 230 days,as opposed to wells in regions with thick Cenozoic layers,greater mining heights and fast rates of longwall advancement.Wells near panel margins achieved relatively better gas production and lasted longer than centerline wells.The rules of development of mining fractures in strata over panels control gas production of surface wells.Mining fractures located in areas determined by lines of compaction and the effect of mining are well developed and can be maintained for long periods of time.Placing the well at the end of panels and on the updip return airway side of panels,determined by lines of compaction and the effect of mining,would result in surface wells for remote pressure relief CBM obtaining their longest gas production periods and highest cumulative gas production.

Research on forced gas draining from coal seams by surface well drilling

Surface drilling was performed at the Luling Coal Mine,in Huaibei,to shorten the period required for gas draining.The experimental study was designed to reduce the cost of gas control by efficiently draining gas from the upper protected layer.The structural arraignment and technical principles of pressure relief via surface drilling are discussed.Results from the trial showed that gas drained from the surface system over a period of 10 months.The total amount of collected gas was 248.4 million m^3.The gas draining occurred in three stages：a growth period;a period of maximum gas production;and an attenuation period.The period of maximum gas production lasted for 4 months.During this time the methane concentration ranged from 60%to 90%and the average draining rate was 10.6 m^3/min.Combined with other methods of draining it was possible to drain 70.6%of the gas from middle coal seam groups.The amount of residual gas dropped to 5.2 m^3/ton,and the pressure of the residual gas fell to 0.53 MPa, thereby eliminating the outburst danger in the middle coal seam groups.The factors affecting pressure relief gas draining by surface drilling were analysed.

Effects of Aerosol Vertical Inhomogeneity on the Upwelling Radiance and Satellite Remote Sensing of Surface Reflectance

There are two widely used radiative models without consideration of aerosol inhomogeneity for satellite remote sensing application, the Homogeneous Model and the Two-layer Model with aerosol in the lower layer. In this paper, effects of the aerosol vertical inhomogeneity on upwelling radiance and satellite remote sensing of surface reflectance are analyzed through numerical simulations by using two models. As shown in the simulations by using 24 representative aerosol models, there is often a considerably large error in upwel-ling radiance calculated by two models (Homogeneous and Two-layer) for the short wavelength channel with strong molecular scattering, owing to the difference between molecular and aerosol scattering proper-ties. For the long wavelength channel, the error is small if aerosol optical parameters are less variable with height, but it could also be significant if there are aerosol layers with different scattering phase functions and single scattering albedo. The radiance errors by the Homogeneous Model and the Two-layer Model can be up to 31.4% and 31.5% for the clean atmosphere, and in case of turbid atmosphere 67.8% and 59.2%, respectively. The radiance error could result in a large uncertainty of surface reflectance retrievals, especially for the short wavelength channel and the strongly absorbing aerosol. For the turbid atmosphere with strong-ly absorbing aerosol, the Homogeneous Model and the Two-layer Model are not suitable for atmospheric correction application. Key words Satellite remote sensing - Aerosol inhomogeneity - Surface reflectance - Radiance

An investigation of surface deformation after fully mechanized,solid back fill mining

The surface deformation after fully mechanized back filling mining was analyzed.The surface deformation for different backfill materials was predicted by an equivalent mining height model and numerical simulations.The results suggest that:(1) As the elastic modulus,E,of the backfill material increases the surface subsidence decreases.The rate of subsidence decrease drops after E is larger than 5 GPa;(2) Fully mechanized back fill mining technology can effectively control surface deformation.The resulting surface deformation is within the specification grade I,which means surface maintenance is not needed.A site survey showed that the equivalent mining height model is capable of predicting and analyzing surface deformation and that the model is conservative enough for engineering safety.Finally,the significance of establishing a complete error correction system based on error analysis and correction is discussed.

Adaptive integral dynamic surface control based on fully tuned radial basis function neural network

An adaptive integral dynamic surface control approach based on fully tuned radial basis function neural network （FTRBFNN） is presented for a general class of strict-feedback nonlinear systems,which may possess a wide class of uncertainties that are not linearly parameterized and do not have any prior knowledge of the bounding functions.FTRBFNN is employed to approximate the uncertainty online,and a systematic framework for adaptive controller design is given by dynamic surface control. The control algorithm has two outstanding features,namely,the neural network regulates the weights,width and center of Gaussian function simultaneously,which ensures the control system has perfect ability of restraining different unknown uncertainties and the integral term of tracking error introduced in the control law can eliminate the static error of the closed loop system effectively. As a result,high control precision can be achieved.All signals in the closed loop system can be guaranteed bounded by Lyapunov approach.Finally,simulation results demonstrate the validity of the control approach.

Surface diffuse discharge mechanism of well-aligned atmospheric pressure microplasma arrays

A stable and homogeneous well-aligned air microplasma device for application at atmospheric pressure is designed and its electrical and optical characteristics are investigated. Current-voltage measurements and intensified charge coupled device （ICCD） images show that the well-aligned air microplasma device is able to generate a large-area and homogeneous discharge at the applied voltages ranging from 12 kV to 14 kV, with a repetition frequency of 5 kHz, which is attributed to the diffusion effect of plasma on dielectric surface. Moreover, this well-aligned microplasma device may result in the uniform and large-area surface modification of heat-sensitive PET polymers without damage, such as optimization in hydrophobicity and biocompatibility. In the biomedical field, the utility of this well-aligned microplasma device is further testified. It proves to be very efficient for the large-area and uniform inactivation of E. coli cells with a density of 103/cm2 on LB agar plate culture medium, and inactivation efficiency can reach up to 99% for 2-min treatment.

An Asthenospheric Upwelling Beneath Central Mongolia——Implications for Intraplate Surface Uplift and Volcanism

Intraplate processes,such as continental surface uplift and intraplate volcanism,are enigmatic and the underlying mechanisms responsible are not fully understood.Central Mongolia is an ideal natural laboratory for studying such processes because of its location in the continental interior far from tectonic plate boundaries.

Fully Coupled Time-Domain Simulation of Dynamic Positioning Semi-Submersible Platform Using Dynamic Surface Control

A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning(DP) system. In the control force design, a dynamic model of reference linear drift frequency in the horizontal plane is introduced. The dynamic surface control(DSC) is used to design a control strategy for the DP. Compared with the traditional back-stepping methods, the dynamic surface control combined with radial basis function(RBF) neural networks(NNs) can avoid differentiating intermediate variables repeatedly in every design step due to the introduction of a first order filter. Low frequency motions obtained from total motions by a low pass filter are chosen to be the inputs for the RBF NNs which are used to approximate the low frequency wave force. Considering the propellers' wear and tear, the effect of filtering frequencies for the control force is discussed. Based on power consumptions and positioning requirements, the NN centers are determined. Moreover, the RBF NNs used to approximate the total wave force are built to monitor the disturbances. With the DP assistance, the results of fully coupled dynamic response simulations are given to illustrate the effectiveness of the proposed control strategy.

Modeling of Surface Tension and Viscosity for Non-electrolyte Systems by Means of the Equation of State for Square-well Chain Fluids with Variable Interaction Range

The equation of state(EOS)for square-well chain fluid with variable range(SWCF-VR) developed in our previous work based on statistical mechanical theory for chemical association is employed for the correlations of surface tension and viscosity of common fluids and ionic liquids(ILs).A model of surface tension for multi-component mixtures is presented by combining the SWCF-VR EOS and the scaled particle theory and used to produce the surface tension of binary and ternary mixtures.The predicted surface tensions are in excellent agreement with the experimental data with an overall average absolute relative deviation(AAD)of 0.36%.A method for the calculation of dynamic viscosity of common fluids and ILs at high pressure is presented by combining Eyring’s rate theory of viscosity and the SWCF-VR EOS.The calculated viscosities are in good agreement with the experimental data with the overall AAD of 1.44% for 14 fluids in 84 cases.The salient feature is that the molecular parameters used in these models are self-consistent and can be applied to calculate different thermodynamic properties such as pVT,vapor-liquid equilibrium,caloric properties,surface tension,and viscosity.

A Self-Consistent Model on Cylindrical Monopole Plasma Antenna Excited by Surface Wave Based on the Maxwell-Boltzmann Equation

The paper analyzes the motion of electron in plasma antenna and the distribution of electromagnetic field power around the plasma antenna, and proposes a self-consistent model according to the structure of cylindrical monopole plasma antenna excited by surface wave;calculation of the model is based on Maxwell-Boltzmann equation and gas molecular dynamics theory. The calculation results show that this method can reflect the relationships between the external excitation power, gas pressure, discharge current and the characteristic of plasma. It is an accurate method to predicate and calculate the parameters of plasma antenna.

Convection of Maxwell fluid over stretching porous surface with heat source/sink in presence of nanoparticles:Lie group analysis

The convection of a Maxwell fluid over a stretching porous surface with a heat source/sink in the presence of nanoparticles is investigated. The Lie symmetry group transformations are used to convert the boundary layer equations into coupled nonlinear ordinary differential equations. The ordinary differential equations are solved numerically by the Bvp4c with MATLAB, which is a collocation method equivalent to the fourth-order mono-implicit Runge-Kutta method. Furthermore, more attention is paid to the effects of the physical parameters, especially the parameters related to nanoparticles, on the temperature and concentration distributions with consideration of permeability and the heat source/sink.

Membrane Fouling Alleviation by Chemically Enhanced Backwashing in Treating Algae-Containing Surface Water: From Bench-Scale to Full-Scale Application

Ultrafiltration(UF)has been increasingly implemented in drinking water treatment plants;however,algae and their secretions can cause severe membrane fouling and pose great challenges to UF in practice.In this study,a simple and practical chemically enhanced backwashing(CEB)process was developed to address such issues using various cleaning reagents,including sodium hypochlorite(NaClO),sodium chloride(NaCl),sodium hydroxide(NaOH),sodium citrate,and their combinations.The results indicate that the type of chemical played a fundamental role in alleviating the hydraulically irreversible membrane fouling(HIMF),with NaClO as the best-performing reagent,followed by NaCl.Furthermore,a CEB process using a combination of NaClO with NaCl,NaOH,or sodium citrate delivered little improvement in the alleviation of membrane fouling compared with NaClO alone.The optimized dosage and dosing frequency of NaClO were 10 mg·L^(-1) two times per day.Long-term pilot-scale and full-scale experiments further verified the feasibility of the CEB process in relieving algae-derived membrane fouling.Compared with the conventional hydraulic backwashing without chemical involvement,the CEB process can effectively remove the organic foulants including biopolymers,humic substances,and proteinlike substances by means of oxidization,thereby weakening the cohesive forces between the organic foulants and the membrane surface.Therefore,the CEB process can efficiently alleviate the algae-related membrane fouling with lower chemical consumption,and is proposed as an alternative to control membrane fouling in treating the algae-containing surface water.

The effect of the attractive well of the potential energy surface for Ne-HC1 on rotationally inelastic partial wave cross sections

An interaction potential of the Ne-HC1 van der Waals complex is obtained by utilizing the Huxley analytic potential function to fit the accurate interaction energy data, which have been computed at the coupled cluster singles and doubles including connected triple excitations level and with the augmented correlation consistent polarized valence quintuple zeta basis set extended with a set of 3s3p2dlflg mid-bond functions [CCSD （T）/aug-cc-pV5Z-33211]. The close coupling calculation of state-to-state partial cross sections for collision of Ne with HC1 is first performed by employing the fitted interaction potential. This calculation is performed at the incident energies： 40, 60, 75 and 100 meV, separately. The effects of the long-range attractive and the short-range anisotropic interactions on the inelastic state-to-state partial cross sections are discussed in detail. Two maxima are present in the rotationally inelastic partial cross sections and they originate from different mechanisms.

The Surface Reactivity and Electronic Properties of Small Hydrogenation Fullerene Cages

Density functional theory calculations within the G03W package, with B3LYP exchange functional and applying basis set 6 - 31 G (d,p) are performed. The surface reactivity and electronic properties of endo-hydrogenation and exo-hydrogenation fullerene cages are studied. It is found that the surface reactivity of mono-hydrogenation fullerene cages is larger than the surface reactivity of un-hydrogenation fullerene cages and the later is larger than the fully hydrogenation fullerene cages. In addition, the calculations show that the endo-hydrogenation fullerene cages possess the same band gaps as the un-hydrogenation fullerene cages, however, the exo-hydrogenation is reduced the band gaps of the un-hydrogenated fullerene cages form ~7 eV to ~5 eV.

Effects of transpiration on unsteady MHD flow of an upper convected Maxwell (UCM) fluid passing through a stretching surface in the presence of a first order chemical reaction

The aim of this article is to present the effects of transpiration on the unsteady two-dimensional boundary layer flow of non-Newtonian fluid passing through a stretching sheet in the presence of a first order constructive/destructive chemical reaction. The upper-convected Maxwell （UCM） model is used here to characterize the non-Newtonian behavior of the fluid. Using similarity solutions, the governing nonlinear partial differential equations are transformed into ordinary ones and are then solved numerically by the shooting method. The flow fields and mass transfer are significantly influenced by the governing parameters. The fluid velocity initially decreases as the unsteadiness parameter increases and the concentration decreases significantly due to the increase in the unsteadiness. The effect of increasing values of transpiration （suction） and the Maxwell parameter is to suppress the velocity field; however, the concentration is enhanced as transpiration （suction） and the Maxwell parameter increase. Also, it is found that the fluid velocity decreases as the magnetic parameter increases; however, the concentration increases in this case.