Preparation and Photocatalytic Properties of Magnetically Separable TiO_2 Supported on Nickel Ferrite

A magnetically separable photocatalyst TiO2/SiO2/NiFe2O4 (TSN) with a typical ferromagnetic hystere- sis was prepared by a liquid catalytic phase transfer method. When the intensity of applied magnetic field weakened to zero, the remnant magnetism of the prepared photocatalyst faded to zero. The photocatalytst can be separated from water when an external magnetic field is added and redispersed into aqueous solution after the external magnetic field is eliminated, that makes the photocatalysts promising for wastewater treatment. Transmission elec-tron microscope (TEM) and X-ray diffractometer (XRD) were used to characterize the structure of the photocatalyst, indicating that the magnetic SiO2/NiFe2O4 (SN) particle was compactly enveloped by P-25 titania and TiO2 shell was formed. The magnetic composite showed high photocatalytic activity for the degradation of methyl orange in water. A thin SiO2 layer between NiFe2O4 and TiO2 shell prevented effectively the leakage of charges from TiO2 particles to NiFe2O4, which gave rise to the increase in photocatalytic activity. Moreover, the experiment on recy-cled use of TSN demonstrated a good repeatability of the photocatalytic activity.

Experimental and Parametric Design of Petroleum Back-pressured Hydraulic Impactor

Percussive-rotary drilling technology was considered many years ago as one of the best approaches for hard rock drilling. It is a key for popularizing this technology on a large scale to design and make an impactor with excellent performance. This paper presents a suit of method to design the percussive parameters for the oil or gas field by introducing the working principle of back-pressured impactor, dividing the working periods of impactor into three phases and establishing the computer emulational model of percussive parameters. It draws a comparison between the results of model calculation and experiment on the basis of analyzing the experiment results of impactor.The conclude provides credible foundation for designing and further ameliorating the impactor.

Solidification and remelting of Al through Al_2O_3 fibrous preform under centrifugal force

The solidification and remelting of molten aluminum through a porous preform under centrifugal force field were modeled numerically. The results show that the transient solidification and remelting phenomena appear on the infiltration front and can be divided into two distinct regions: the remelting region and solid-liquid congruent melting region. The decrease of porosity always results in the increase of moving velocity difference between the infiltration front and the remelting front, which leads to the increase of the solid-liquid congruent region extent. But for the decrease of the rotational frequency, the difference of moving velocity between infiltration front and remelting front decreases, which leads to the decrease of regional extent. The infiltration front moving velocity is mainly influenced by the centrifugal infiltration pressure, whereas the remelting front moving velocity is mainly influenced by the material thermodynamics. The transient solidification and remelting phenomena are the intercoupling results between the centrifugal infiltration dynamics and the material thermodynamics.

Allocation of Energy Use in the Biomass-based Fuel Ethanol System and Its Use in Decision Making

The Chinese government is developing biomass ethanol as one of its automobile fuels for energy security and environmental improvement reasons. The energy efficiency of the biomass-based fuel ethanol is critical issue. To investigate the energy use in the three biomass-base ethanol fuel systems, energy content approach, Market value approach and Product displacement approach methods were used to allocate the energy use based on life cycle energy assessment. The results shows that the net energy of corn based, wheat based, and cassava-based ethanol fuel are 12543MJ, 10299MJ and 13112MJ when get one ton biomassbased ethanol, respectively, and they do produce positive net energy.

Facile preparation of core-shell Si@Li4Ti5O12 nanocomposite as large-capacity lithium-ion battery anode

As a promising alternative anode material,silicon(Si)presents a larger capacity than the commercial anode to achieve large capacity lithium-ion batteries.However,the application of pure Si as anode is hampered by limitations such as volume expansion,low conductivity and unstable solid electrolyte interphase.To break through these limitations,the core-shell Si@Li4Ti5O12nanocomposite,which was prepared via in-situ self-assembly reaction and decompressive boiling fast concentration method,was proposed in this work.This anode combines the advantages of nano-sized Si particle and pure Li4Ti5O12(LTO)coating layer,improving the performance of the lithium-ion batteries.The Si@Li4Ti5O12 anode displays a high initial discharge/charge specific capacity of 1756/1383 m Ahg^-1 at 500 mAg^-1(representing high initial coulombic efficiency of 78.8%),a large rate capability(specific capacity of 620 mAhg^-1 at4000 mAg^-1),an outstanding cycling stability(reversible specific capacity of 883 mAhg^-1 after 150 cycles)and a low volume expansion rate(only 3.3% after 150 cycles).Moreover,the synthesis process shows the merits of efficiency,simplicity,and economy,providing a reliable method to fabricate large capacity Si@Li4Ti5O12nanocomposite anode materials for practical lithium-ion batteries.

Design of capacitance sensor system for void fraction measurement

Simulation and optimization were applied to a capacitive sensor system based on electrical tomography technology. Sensors, consisting of Morgantown Energy Technology Center (METC) axial synchro driving guard electrodes and two sets of detecting electrodes, make it possible to obtain simultaneously two groups of signals of the void fraction in oil-gas two-phase flow. The computational and experimental results showed that available sensors, charactered by high resolution and fast real-time response can be used for real-time liquid-gas two-phase flow pattern determination.

Effect of water injection on hydrogen generation during severe accident in PWR

Effect of water injection on hydrogen generation during severe accident in a 1000 MWe pressurized water reactor was studied. The analyses were carried out with different water injection rates at different core damage stages. The core can be quenched and accident progression can be terminated by water injection at the time before cohesive core debris is formed at lower core region. Hydrogen generation rate decreases with water injection into the core at the peak core temperature of 1700 K, because the core is quenched and reflooded quickly. The water injection at the peak core temperature of 1900 K, the hydrogen generation rate increases at low injection rates of the water, as the core is quenched slowly and the core remains in uncovered condition at high temperatures for a longer time than the situation of high injection rate. At peak core temperature of 2100–2300 K, the Hydrogen generation rate increases by water injection because of the steam serving to the high temperature steam-starved core. Hydrogen generation rate increases significantly after water injection into the core at peak core temperature of 2500 K because of the steam serving to the relocating Zr-U-O mixture. Almost no hydrogen generation can be seen in base case after formation of the molten pool at the lower core region. However, hydrogen is generated if water is injected into the molten pool, because steam serves to the crust supporting the molten pool. Reactor coolant system (RCS) depressurization by opening power operated relief valves has important effect on hydrogen generation. Special attention should be paid to hydrogen generation enhancement caused by RCS depressurization.

High-efficiency magnetophoretic separation based on synergy of magnetic force field and flow field in microchannels

Magnetophoresis is one of the most important separation methods in biological and chemical engineering. In this paper,a novel impact parameter on separation efficiency,i.e.,the angle between the vectors of magnetic force and fluid velocity,was derived from the basic equation describing the motion of magnetic beads in microchannels. It is proposed that one of the most important approaches for separation efficiency enhancement is to improve the coordination of magnetic force field and fluid flow field. A T-shaped microchannel magnetophoretic separator was designed based on the angle. And then a two-dimensional dynamic model of magnetic beads moving in microchannels was established to study the separation efficiency of T-shaped microseparator by combined use of finite element method and Runge-Kutta method. The results show that the capture effi-ciency of T-shaped microseparator is much higher than that of the straight microseparator at the same conditions. For small magnetic beads at high fluid velocities,the designed T-shaped microseparator could still keep high separation efficiency whereas the conventional straight microseparator fails to separate the magnetic beads. Further analysis shows that the mechanism of separation efficiency enhancement lies in the synergy of magnetic force field and flow field,which directly leads to large deflected velocity of the magnetic beads from the main stream,and thus increasing the separation efficiency. It is anticipated that the results in this paper are theoretically helpful for the optimum design of highly efficient magnetophoretic separators.

Effect of Magnetic Carrier NiFe2O4 Nanoparticles on Physicochemical and Catalytic Properties of Magnetically Separable Photocatalyst TiO2/NiFe2O4

A series of magnetically separable photocatalyst TiO2/NiFe2O4（TN） with different mass ratios of NiFe204 to TiO2 was prepared by sol-gel method. The X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, transmission electron microscopy（TEM）, ultraviolet-visible spectroscopy（UV-Vis）, Brunauer-Emmett-Teller（BET） surface analysis and photoluminescence spectroscopy（PL） were used to characterize the photocatalyst TN. The XRD patterns of TN indicate that adulterating a smidgen of NiFe204 into TiOR（about 0.1%, mass ratio） can promote the phase transformation of TiO2, however, when the doped amount of NiFe2O4 surpasses 1%, the introduction of NiFe2O4 can inhibit the growth of YiO2 crystal grain and reduce the size of TiO2 crystal grain. The XPS results of TN indicate that some Fe3＋ replace Ti4＋ of the TiO2 lattice forming Fe--O--Ti bonds. The PL analysis of TN shows that the NiFezO4 nanoparticles in photocatalyst TN play the role of the effective recombination centre of the photogenerated electrons and holes, leading to the decrease in photocatalytic activity.

Effect of coating thickness on the calibration and measurement uncertainty of a wide-band liquid crystal thermography

The liquid crystal thermography is a high-resolution and non-intrusive optical technique for full-field temperature measurement.We present detailed calibration data for a wide-bandwidth thermochromic liquid crystal（TLC） to investigate the effect of the coating thickness on the hue-temperature characteristics and the measurement uncertainty of the TLC.It is found that the coating thickness has appreciable effect on the TLC hue-temperature curve.For TLC coatings with the thickness over 20μm,a thicker TLC coating shows a relatively smaller measurement uncertainty,but the effect of the coating thickness is non-distinctive on the measurement uncertainty.

Tribological Properties of API 10-Round Thread Connection During Make-and-Break Process

Galling is one of the most familiar failure forms for tubing and casing connections. It has been regarded as a key problem by metallurgy and petroleum systems all over the world. The theory of tribology and contact mechanics was used to analyze the contact force, plastic strain, and other parameters of API 10-round tubing connections in the process of makeup and breakout using the nonlinear finite element method. The stress states of the tubing thread connections were also analyzed for combined makeup and axial tensile loads. The results show that the main factors for tubing thread galling failure with thread grease are the normal contact force of the pin and box and the rigidity of the thread surface. The distribution of the contact force can be improved and the high contact force of the local thread can be reduced by optimizing the geometric parameters of the thread or using a small or varied pitch. The thread surface rigidity can be increased by improving the thread surface machining quality and by heat treatment. The chance of tubing thread galling failure can be reduced by designing hydraulic pressure tongs to avoid high speed and high torque makeup and by standardizing the operations of oilfield makeup and breakout.

Tailored morphology and highly enhanced phonon transport in polymer fibers:a multiscale computational framework

Although tremendous efforts have been devoted to enhance thermal conductivity in polymer fibers,correlation between the thermal-drawing conditions and the resulting chain alignment,crystallinity,and phonon transport properties have remained obscure.Using a carefully trained coarse-grained force field,we systematically interrogate the thermal-drawing conditions of bulk polyethylene samples using large-scale molecular dynamics simulations.An optimal combination of moderate drawing temperature and strain rate is found to achieve highest degrees of chain alignment,crystallinity,and the resulting thermal conductivity.Such combination is rationalized by competing effects in viscoelastic relaxation and condensed to the Deborah number,a predictive metric for the thermal-drawing protocols,showing a delicate balance between stress localizations and chain diffusions.Upon tensile deformation,the thermal conductivity of amorphous polyethylene is enhanced to 80% of the theoretical limit,that is,its pure crystalline counterpart.An effective-medium-theory model,based on the serial-parallel heat conducting nature of semicrystalline polymers,is developed here to predict the impacts from both chain alignment and crystallinity on thermal conductivity.The enhancement in thermal conductivity is mainly attributed to the increases in the intrinsic phonon mean free path and the longitudinal group velocity.This work provides fundamental insights into the polymer thermal-drawing process and establishes a complete process–structure–property relationship for enhanced phonon transport in all-organic electronic devices and efficiency of polymeric heat dissipaters.

3D Printed Ultrastretchable,Hyper-Antifreezing Conductive Hydrogel for Sensitive Motion and Electrophysiological Signal Monitoring

Conductive hydrogels with high stretchability can extend their applications as a flexible electrode in electronics,biomedicine,human-machine interfaces,and sensors.However,their time-consuming fabrication and narrow ranges of working temperature and working voltage severely limit their further potential applications.Herein,a conductive nanocomposite network hydrogel fabricated by projection microstereolithography(PμSL)based 3D printing is proposed,enabling fast fabrication ability with high precision.The 3D printed hydrogels exhibit ultra-stretchability(2500%),hyper-antifreezing(-125℃),extremely low working voltage(<100μV),and super cyclic tensile stability(1 million cycles).The hydrogel-based strain sensor can probe both large-scale and tiny human motions,even with ultralow voltage of 100μV at extremely low temperature around-115℃.It is demonstrated that the present hydrogels can be used as a flexible electrode for capturing human electrophysiological signals(EOG and EEG),where the alpha and beta waves from the brain can be recorded precisely.Therefore,the present hydrogels will pave the way for the development of next-generation intelligent electronics,especially for those working under extremely lowtemperature environments.

Wear Debris Analysis: Fundamental Principle of Wear-Graphy

A new wear-graphy technology was developed, which can simultaneously identify the shape and composition of wear debris, for both metals and non-metals. The fundamental principles of the wear-graphy system and its wear-gram system are discussed here. A method was developed to distribute wear debris on a slide uniformly to reduce overlapping of wear debris while smearing. The composition identification ana-lyzes the wear debris using the scanning electron microscope (SEM) energy spectrum, infrared-thermal im-aging and X-ray imaging technology. A wear debris analysis system based on database techniques is demon-strated, and a visible digitized wear-gram is acquired based on the information of wear debris with image collection and processing of the wear debris. The method gives the morphological characteristics of the wear debris, material composition identification of the wear debris, intelligent recognition of the wear debris, and storage and management of wear debris information.

Thermal Transport in Nanoporous Yttria-Stabilized Zirconia by Molecular Dynamics Simulation

Yttria-stabilized zirconia(YSZ) is widely used as thermal barrier coatings(TBCs) to reduce heat transfer between hot gases and metallic components in gas-turbine engines. Porous structure can generally reduce the lattice thermal conductivity of bulk material, so porous YSZ can be potentially used as TBCs with better thermal performance. In this work, we investigate the thermal conductivity of nanoporous YSZ using the nonequilibrium molecular dynamics(NEMD) simulation, and comprehensively discuss the effects of cross-sectional area, pore size, structure length, porosity, Y_2O_3 concentration and temperature on the thermal conductivity. To compare with the results of the NEMD simulation, we solve the heat diffusion equation and the gray Boltzmann transport equation(BTE) to calculate the thermal conductivity of the same porous structure. From the results,we find that the thermal conductivity of YSZ has a weak dependence on the structure length at the length range from 10 to 26 nm, which indicates that the majority of heat carriers have very short mean free path(MFP) but there exists small percentage(about 3%) of phonons with longer MFP(larger than 10 nm) contributing to the thermal conductivity. The thermal conductivity predicted by NEMD simulation is smaller than that of solving heat diffusion equation(diffusive limit) with the same porous structure. It shows that the presence of pores affects phonon scattering and further affects the thermal conductivity of nanoporous YSZ. The results agree well with the solution of gray BTE with a average MFP of 0.6 nm. The thermal conductivity of nanoporous YSZ weakly depends on the Y_2O_3 concentration and temperature, which shows the phonons with very short MFP play the major contribution to the thermal conductivity. The results help to better understand the heat transfer in porous YSZ structure and develop better TBCs.

A liquid crystal thermography calibration with true color image processing

Liquid crystal thermography is a high-resolution, non-intrusive optical technique for full-field temperature measurement. We present the detailed calibration data for the thermochromic liquid crystal （TLC） with a useful range of 41-60 ℃. The calibration is done with true color image processing by using an isothermal calibrator. The hue-temperature curve of the TLC is obtained, and the measurement uncertainty is analyzed. Combined with the image noise reduction technique of a 5×5 median filter, the measurement accuracy of the liquid crystal thermography can be significantly improved by approximately 57.1%.

Framework for Grid Manufacturing

With the development of networked manufacturing, it is more and more imminent to solve prob-lems caused by inherent limitations of network technology, such as heterogeneity, collaboration collision, and decentralized control. This paper presents a framework for grid manufacturing, which neatly combines grid technology with the infrastructure of advanced manufacturing technology. The paper studies grid-oriented knowledge description and acquisition, and constructs a distributed knowledge grid model. The pa-per also deals with the protocol of node description in collaborative design, and describes a distributed col-laborative design model. The protocol and node technology leads to a collaborative production model for grid manufacturing. The framework for grid manufacturing offers an effective and feasible solution for the problems of networked manufacturing. The grid manufacturing will become an advanced distributed manu-facturing model and promote the development of advanced manufacturing technologies.