外加电对边界油润滑下摩擦系数的影响

利用外加电压实现对摩擦系数的主动控制是摩擦学者长期追求的目标之一.本实验应用球盘式摩擦试验机,针对150SN油润滑下的GCr15/45#摩擦副,考察了外加直流电压极性、外加直流电流大小、以及外加交流电压的频率对其摩擦和润滑性能的影响,并对其作用机理进行了分析.实验结果表明,外加直流电压的极性对GCr15/45#摩擦副间的摩擦系数和润滑状况有很大的影响;一定范围内的外加电流大小的影响只是程度上的不同而已;外加交流电压的影响则综合了由极性和幅值的变化所带来的影响,其变化频率也是重要的摩擦学性能影响参数.结合作者先前的工作及其他有关文献,对外加电压的影响机理进行了初步分析,认为外加电是通过影响界面摩擦电化学反应所形成的表面氧化膜的性质和状态来影响摩擦和润滑性能的.

外加电控制YG8/TC4摩擦副的试验研究

用配置在车床上的摩擦磨损试验辅助装置研究了热电回路的状态,外加电压大小、方向对刀具工件摩擦副——YG8硬质合金/TC4钛合金的摩擦磨损性能的影响。试验结果表明,断开热电回路和在摩擦副间施加反向调零电压对于减小摩擦系数,抑制YG8刀片的磨损,减小TC4圆盘摩擦表面的Ra值都有显著的效果,同时在摩擦副间施加反向电压时的摩擦磨损性能要优于施加正向电压,施加±6V时摩擦副的性能要优于±4V,这可以为钛合金的切削研究提供试验参考。

外加电对植物生长影响的初探

外加电对植物生长影响的初探杜春红（双阳县林业局）植物生长过程，在有机肥不足的情况下，对植物连年大量追施化肥，其结果不仅影响苗木的质量，而且对土壤造成不良影响。对植物进行外加电处理，既可以解决有机肥不足，又可以加速植物的生长，现将试验情况作一简要介绍。...

杜尔外加电雾化器积漆的原因与对策

介绍了杜尔外加电雾化器外部积漆的形态,分析了可能的原因,并给出了预防措施。

外加电旋杯在水性2C1B短工艺中的应用

介绍了水性涂料二涂层涂装二涂一烘(2C1B)短工艺的特点,喷涂系统在水性2C1B短工艺中的应用情况,以及东风乘用车新能源工厂开发的新工艺模式:外加电旋杯PPH707 Ext在水性2C1B短工艺中的应用和相关问题的解决。

Influence of external nitrogen-containing donors on polymerization behavior of neodymium-based cis-1,4-polybutadiene rubber

Neodymium(Nd)-based catalyst in butadiene(Bd)polymerization has drawn interests due to its availability in affording higher cis-1,4-unit selectivity than transition metal(Ti,Co,Ni,etc.)-based catalysts[1-2].Such outstanding high cis-1,4-unit selecti-vity is hypothetically originated from the presence of 4 f orbitals,that can participate in monomer coordination and thereby govern subsequent enchainment manners.This unique characteristic also renders the active species highly susceptible to Lewis bases,and may impact the overall selectivity as well as polyme-rization behavior after coordination.Nevertheless,it is still a virgin area in such a field,and the influence of Lewis bases on Nd-based diene polymerizations is still a black box.Based on this consideration,how nitrogen-containing donors(D)impacts the overall behaviors of Nd-mediated Bd polymerizations is disclosed.

机器人喷涂水性漆时滴漆问题的解决

在用机器人外加电旋杯喷涂水性色漆时,普遍存在漆雾附着在静电发生器(手指)处而导致的积漆问题,这些积漆久而久之会变成漆滴并落在车身表面,烘干后形成水滴状弊病。通过对生产现场案例的分析,探讨了造成这种现象的原因。虽然积漆本身不可避免,但是喷漆环境、喷漆参数和机器人日常维护都是不可忽视的因素。通过对外置静电发生器进行优化,调整喷漆室风速,调整成型空气,以及微调机器人仿形,最终解决了问题。

Analytical model for power dissipation in cell membranes in suspensions exposed to electric fields

Due to interaction among cells, it is too complex to build an exactanalytical model for the power dissipation within the cell membrane in suspensions exposed toexternal fields. An approximate equivalence method is proposed to resolve this problem. Based on theeffective medium theory, the transmembrane voltage on cells in suspensions was investigated by theequivalence principle. Then the electric field in the cell membrane was determined. Finally,analytical solutions for the power dissipation within the cell membrane in suspensions exposed toexternal fields were derived according to the Joule principle. The equations show that theconductive power dissipation is predominant within the cell membrane in suspensions exposed todirect current or lower frequencies, and dielectric power dissipation prevails at high frequenciesexceeding the relaxation frequency of the exposed membrane.

Grain Size Effect on Electrical Conductivity and Giant Magnetoresistance of Bulk Magnetic Polycrystals

By solving the Boltzmann transport equation and considering the spin-dependent grain boundary scattering, the distribution of electrons in grains and the electrical transport properties in the applied magnetic field are studied. With regard to the dominant influence of grain boundary scattering which is taken as a boundary condition for the electrical transport, the grain size-dependent electrical conductivity is investigated. In addition, the reorientation of the relative magnetization between grains brings the change of the electron spin when the magnetonanocrystailine material is subjected to the magnetic field, resulting in the remarkable giant magnetoresistance effect.

Effect of direct electric current on wetting behavior of molten Bi on Cu substrate

The effect of direct electric current on the wetting behavior of molten Bi on Cu substrate at 370℃ was investigated by the sessile drop method. The wettability of molten Bi on Cu without an applied current is poor and the spreading time required to form the steady-state contact angle （about 102°） is approximately 30 min. With the increase of the applied electric current, the spreading of molten Bi on Cu is accelerated significantly and the steady-state contact angle decreases considerably. The cross-section SEM micrographs of the solidified Bi droplet on Cu substrate show that the electric current has a marked effect on the convection of melt. Correspondingly, the application of an electric current obviously enhances the dissolution of Cu into Bi melt, which may change the wetting triple line configuration. The improvement of wettability induced by electric current is also related to the additional driving force for wetting provided by the electromagnetic pressure gradient force.

Destruction of Spiral Wave Using External Electric Field Modulated by Logistic Map

Evolution of spiral wave generated from the excitable media within the Barkley model is investigated. The external gradient electric field modulated by the logistic map is imposed on the media （along x- and y-axis）. Drift and break up of spiral wave are observed when the amplitude of the electric field is modulated by the chaotic signal from the logistic map, and the whole system could become homogeneous finally and the relevant results are compared when the gradient electric field is modulated by the Lorenz or Rossler chaotic signal.

Cathodic electrophoretic deposition of α-Fe_2O_3 coating

Submicro α-Fe2O3 coatings were formed using electrophoretic deposition(EPD) technique in aqueous media. The zeta potentials of different α-Fe2O3 suspensions with different additives were measured as a function of p H to identify the optimum suspension condition for deposition. Electrophoretic depositions of α-Fe2O3 coatings under different applied electric fields and deposition time were studied and the effects of applied voltages and deposition time on deposition rates and thicknesses were investigated. The particle packing densities of the deposits at various applied voltages and deposition time were also analyzed by a scanning electron microscope(SEM). The results show that crack-free α-Fe2O3 coatings with uniform microstructure and good adherence to the nickel substrates are successfully obtained. Electrophoretic deposited α-Fe2O3 coating from aqueous suspension is a feasible, low-cost and environmental friendly method.

Bond Property Test of Reinforced Concrete with All Soaking and Impressed Current Method Corrosion

In order to research the bond properties between corroded reinforcement bars and concrete,reinforcement bars with different diameters and different types and concrete with different strength levels were treated specially with all soaking and impressed current method,and the bond properties were measured with the pull-out test.The comparative analysis of the bond properties of corroded reinforcement bars was carried out.The results showed that the types of reinforcement bars and concrete had great influence on the bond strength.The corrosion and volume expansion of reinforcement bars made concrete in tensile condition,which tended to produce cracks in parallel reinforced direction.The typical bond failure of plain reinforcement bars was pull-out,while the typical bond failure of ribbed reinforcement bars was split.The bond strength between corroded reinforcement bars and concrete increased with the increase of concrete strength.The bond strength of plain and ribbed reinforcement bars showed a decreasing trend after the first increase with the increase of the extent of corrosion.Through the test,the coefficients of the bond strength of plain and ribbed reinforcement bars were given,respectively.

On ferroelectric domain polarization switching mechanism subject to an external electric field by simulations with the phase-field method

The ferroelectric domain formation(FDF) and polarization switching(FDPS) subjected to an external electric field are simulated using the phase-field(PF) method,and the FDPS mechanism under different external electric fields is discussed.The results show that the FDF is a process of nucleation and growth in ferroelectric without applying any external stress.Four kinds of parallelogram shaped ferroelectric domains are formed at the steady state,in which the 180° anti-phase domains regularly align along the 45° direction and the 90° anti-phase domains regularly distribute like a stepladder.Steady electric fields can rotate domain polarization by 90° and 180°,and force the orientation-favorite domains and the average polarization to grow into larger ones.The greater the steady electric field,the larger the average polarization at the steady state.In ferroelectrics subject to an alternating electric field,domain polarization switches to cause a hysteresis loop and an associated butterfly loop with the alternating electric field.The coercive field and remnant field are enhanced with the increase of the electric field frequency or strength,or with the decrease of temperature.

Effects of different external carbon sources and electron acceptors on interactions between denitrification and phosphorus removal in biological nutrient removal processes

The effects of two different external carbon sources （acetate and ethanol） and electron acceptors （dissolved oxygen, nitrate, and nitrite） were investigated under aerobic and anoxic conditions with non-acclimated process bi- omass from a full-scale biological nutrient removal-activated sludge system. When acetate was added as an external carbon source, phosphate release was observed even in the presence of electron acceptors. The release rates were 1.7, 7.8, and 3.5 mg P/（g MLVSS.h） （MLVSS： mixed liquor volatile suspended solids）, respectively, for dissolved oxygen, nitrate, and nitrite. In the case of ethanol, no phosphate release was observed in the presence of electron acceptors. Results of the experiments with nitrite showed that approximately 25 mg NO2-N/L of nitrite inhibited anoxic phosphorus uptake regardless of the concentration of the tested external carbon sources. Furthermore, higher deni- trification rates were obtained with acetate （1.4 and 0.8 mg N/（g MLVSS.h）） compared to ethanol （1.1 and 0.7 mg N/ （g MLVSS.h）） for both anoxic electron acceptors （nitrate and nitrite）.

Study on electro-optic properties of two-dimensional PLZT photonic crystal band structure

The band characteristics of two-dimensional(2D) lead lanthanum zirconate titanate(PLZT) photonic crystals are analyzed by finite element method.The electro-optic effect of PLZT can cause the refractive index change when it is imposed by the applied electric field,and the band structure of 2D photonic crystals based on PLZT varies accordingly.The effect of the applied electric field on the structural characteristics of the first and second band gaps in 2D PLZT photonic crystals is analyzed in detail.And the results show that for each band gap,the variations of start wavelength,cut-off wavelength and bandwidth are proportional to quadratic of the electric field.

An Exotic Phase Change in Dynamic Electrorheological Fluids

It is well known that constant or time-varying electric fields can induce phase changes in electrorheological(ER) fluids, from a liquid to semi-solid state, provided the field strength is larger than some critical value. We describe here an experimental and theoretical study considering yet a different class of phase changes, specifically those for an ER fluid in the presence of both shear flow and a time-varying electric field. We note that as the frequency of the field is decreased, the ER fluid will go from a liquid to an intermediate transition state, and eventually to a shear banding state. Our theoretical analysis further indicates that this phase change originates from competing effects of viscous and electrical forces. Ultimately, we conclude that it is possible to achieve various states and corresponding(desired)macroscopic properties of dynamic colloidal suspensions by adjusting the frequency of the externally applied electric field.

Spin Splitting in Different Semiconductor Quantum Wells

We theoretically investigate the spin splitting in four undoped asymmetric quantum wells in the absence of external electric field and magnetic field.The quantum well geometry dependence of spin splitting is studied with the Rashba and the Dresselhaus spin-orbit coupling included.The results show that the structure of quantum well plays an important role in spin splitting.The Rashba and the Dresselhaus spin splitting in four asymmetric quantum wells are quite different.The origin of the distinction is discussed in this work.

Direct growth of tungsten oxide nanorods from heated tungsten foils

Tungsten oxide （W18O49） nanorods were grown by directly heating tungsten foils covered with potassium bromide （KBr） in low-pressure wet oxygen. The approach featured such advantages as convenient manipulation, low cost and rapid accessibility to high temperatures. A solid-liquid-solid （SLS） mechanism is believed to have dominated the growth process, in which the W18049 nanorods segregated from eutectic droplets of potassium tungstate and tungsten oxide. The ultraviolet photoelectron spectroscopy （UPS） analysis disclosed that the valence band maximum （VBM） of these nanorods was approximately 9 eV be- low the vacuum level. The feasibility of using the such-fabricated nanorods as field emitters was tested and the related mecha- nism was also discussed.

Manipulation of Persistent Spin Helix States by Weak External Magnetic Fields

We study theoretically the effect of weak external magnetic fields on persistent spin helix states in semiconductor two-dimensional electron gases with both Rashba and linear-in-momentum Dresselhaus spin-orbit coupling.We show that in the presence of weak external magnetic fields, some basic properties of a persistent spin helix state,including the dispersion relation between the decay time and the magnitude of the wavevector, the maximum decay time and the value of the characteristic magnitude of the wavevector at which the maximum decay time occurs, will all depend sensitively on the directions of applied external magnetic fields.