石墨电极连接旋合度的研究

在弹性变形分析和数学分析的基础上,对石墨接头与本体连接时的状态进行理论分析与研究,确定实现电极理想连接的条件并通过实验验证。以理论研究为根据,制造出快速确定通过接头连接电极本体时的旋合标记的检测工具。

石墨电极对接试验旋合度及其加工控制的探讨

介绍了石墨电极对接试验旋合度的概念及加工时对其进行检测控制的重要性和必要性,提出了简便可行的测量计算方法并对检测控制要求进行了分析探讨,对加工过程对接试验所测旋合度的检测控制情况进行了简要统计分析。

电极连接试验的研究

对石墨电极的连接状况进行了研究，提出了旋合度、嵌合量等概念，并以此进行连接试验，提出了以 Z值作为评定连接效果的判定值。

进一步提高石墨电极机械加工质量的几点建议

对近年来在石墨电极机械加工中出现的电极孔锥螺纹长度、端部螺纹打半扣长度、螺纹加工梳刀、电极锥螺纹齿形测量,组合机床的维修,锥螺纹联接旋合度的设定等问题,提出几点参考性建议。

Effects of rotational speed and fill level on particle mixing in a stirred tank with different impellers

The particle mixing was studied in a cylindrical stirred tank with elliptical dished bottom by experiments and simulations.The impeller types used were double helical ribbon(HR) + bottom HR,pitched blade ribbon + bottom HR,inner and outer HR + bottom HR,and pitched blade ribbon + Pfaudler + bottom HR labeled as impellers Ⅰ to Ⅳ,respectively.The quantitative correlations among the rotational speed,fill level and power consumption for impeller Ⅰ and impeller Ⅱ were obtained by experiments to validate the discrete element method(DEM) simulations.The particle mixing at different operating conditions was simulated via DEM simulations to calculate the mixing index using the Lacey method,which is a statistical method to provide a mathematical understanding of the mixing state in a binary mixture.The simulation results reveal that as the rotational speed increases,the final mixing index increases,and as the fill level increases,the final mixing index decreases.At the same operating conditions,impeller Ⅲ is the optimal combination,which provides the highest mixing index at the same revolutions.

Optimum traveling and rotation speeds in friction stir welding for dissimilar Al alloys

Aluminum alloys are subjected to large deformation and decreased strength due to the high expansion modulus caused by heat effects during friction stir welding （FSW）.The optimum conditions for friction stir welding of 5052-O and 6061-T6 Al alloys were determined.The optimum traveling and rotation speeds were identified to be 61mm/min and 1600r/min using various mechanical characteristic evaluation methods.

Mixing ratio design of emulsified asphalt cold recycled mixture based on gyratory compaction molding

In order to study the application of gyratory compaction molding method in emulsified asphalt cold recycled mixture and optimize the relevant technical parameters, the study was carried out according to splitting strength, stability and water stability test;the design of the experiment involved changing gyration number, emulsified asphalt and water content, molded specimen temperature and other factors to analyze the volume parameters, mechanical properties and water stability. The results show that both the maximum dry density and dry and wet splitting strength ratio(DWSSR) of emulsified asphalt cold reclaimed mixture are improved by the rotary compacting method, while the porosity and the optimal dosage of water are reduced. Furthermore, with the increase of compaction times, the porosity and splitting strength index both change exponentially. DWSSR and porosity are consistent with quadratic functions. The use of gyratory compaction for 70 times at 25 °C and the optimum dosage of emulsified asphalt can be determined based on the splitting strength ratio. The high-temperature stability and water damage resistance of the pavement can be improved by the use of rotary compacting method effectively, and the early strength and road performance are higher than the regulatory requirements.

Influences of diffusion bonding process parameters on bond characteristics of Mg-Cu dissimilar joints

In many circumstances,dissimilar metals have to be bonded together and the resulting joint interfaces must typically sustain mechanical and/or electrical forces without failure,which is not possible by fusion welding processes.The melting points of magnesium(Mg)and copper(Cu)have a significant difference(nearly 400℃)and this may lead to a large difference in the microstructure and joint performance of Mg-Cu joints.However,diffusion bonding can be used to join these alloys without much difficulty.This work analyses the effect of parameters on diffusion layer thickness,hardness and strength of magnesium-copper dissimilar joints.The experiments were conducted using three-factor,five-level,central composite rotatable design matrix.Empirical relationships were developed to predict diffusion layer thickness,hardness and strength using response surface methodology.It is found that bonding temperature has predominant effect on bond characteristics.Joints fabricated at a bonding temperature of 450℃, bonding pressure of 12 MPa and bonding time of 30 min exhibited maximum shear strength and bonding strength of 66 and 81 MPa, respectively.

Response Surface Optimization for Process Parameters of LiFePO_4/C Preparation by Carbothermal Reduction Technology

A statistically based optimization strategy is used to optimize the carbothermal reduction technology for the synthesis of LiFePO4/C using LiOH,FePO4 and sucrose as raw materials.The experimental data for fitting the response are collected by the central composite rotatable design(CCD).A second order model for the discharge ca-pacity of LiFePO4/C is expressed as a function of sintering temperature,sintering time and carbon content.The ef-fects of individual variables and their interactions are studied by a statistical analysis(ANOVA).The results show that the linear effects and the quadratic effects of sintering temperature,carbon content and the interactions among these variables are statistically significant,while those effects of sintering time are insignificant.Response surface plots for spatial representation of the model illustrate that the discharge capacity depends on sintering temperature and carbon content more than sintering time.The model obtained gives the optimized reaction parameters of sinter-ing temperature at 652.0 ℃,carbon content of 34.33 g?mol-1 and 8.48 h sintering time,corresponding to a dis-charge capacity of 150.8 mA·h·g-1.The confirmatory test with these optimum parameters gives the discharge ca-pacity of 147.2 and 105.1 mA·h·g-1 at 0.5 and 5 C,respectively.

Magnetic Properties of Ferromagnetic Double Layers with Ferrimagnetic Interlayer Coupling at Zero Temperature

Spin-wave theory is used to study magnetic properties of ferromagnetic double layers with a ferrimagnetic interlayer coupling at zero temperature. The spin-wave spectra and four sublattices magnetizations and internal energy are calculated by employing retarded Green function technique. The sublattice magnetizations at ground state are smaller than their classical values, owing to the zero-point quantum fluctuations of the spins.

Theoretical and Experimental Study on Ground Coupled Heat Pump with Vertical Spiral Coil

The numeric al simulation study on the temperature distribution of underground field for the ground coupled heat pump (GCHP) with vertical spira l coil was carried out by using finite element. The distribution and recovery of undergroun d field temperature under different operation ratio and the optimal operation ratio were simulated.The performance parameters, i.e. inlet and outlet temperature of the ground spiral coil in heating and cooling modes were tested, the heat extracted or emitted by the heat pump to the ground was calculated, and the coefficients of performance (COP) of GCHP at heat ing and cooling modes were analyzed.

Structural considerations in friction welding of hybrid Al_2O_3-reinforced aluminum composites

Comparative studies on the relationship between the welding parameters and joining efficiency in the friction welding of hybrid Al203-reinforced aluminum composites were conducted. Metal matrix composites （MMCs） with 37% （volume fraction） aluminum particle were joined by friction welding. The results show that the effects of the rotation speed on the reduction rate of particle size are greater than those of the upset pressure, and the area of the MMC weld zone decreases as the joining efficiency increases, while it is considered that the joining efficiency does not increase as the reduction rate of particle size decreases. During the macro-examination of the bonding interlace, a gray discolored region was observed on the bonding interface, and the center of the region was dark gray. After the micro-examination of the bonding interface, base metal made some second particulate formed by condensed alumina particulate but discoloration part distributed minute alumina particulate without second particulate. Consequently, it was also observed that rotational speed of 3 000 r/min and upset pressure of 63.6 MPa showed a very good.joint.

Effects Analysis of Mg^2＋, dNTPs and Taq DNA Polymerase on SSR-PCR System of Pear

Effects of Mg^2＋, NTPs and Taq DNA polymerase in pear SSR-PCR system were analyzed by quadratic regressive orthogonal rotational combinational design. Results showed： absolute IOD （Integrated OD of each band） value of target band reduced with concentration rising of Mg^2＋ and Taq DNA polymerase, but heightened with concentration rising of dNTPs. The decay rate of absolute IOD value increased progressively with rising Mg^2＋ concentration, decreased gradually with rising Taq DNA polymerase concentration; the rising speed would be slower than the dNTPs increase. Absolute IOD value would reduce with concentration rising of dNTPs at a low level of Mg^2＋ concentration. Conversely it would rise with the increase of dNTPs while high Mg^2＋ concentration. Absolute IOD value would generally rise with concentration rising of Taq DNA polymerase while low Mg^2＋ concentration. On the contrary it would reduce with concentration rising of Taq DNA polymerase while high Mg^2＋ concentration.

Disentanglement of Two Qubits Coupled to an XY Spin Chain at Finite Temperature

The disentanglement evolution of bipartite spin-1/2 system coupled to a common surrounding XY chain in transverse fields at nonzero temperature is studied in this letter. The dynamical process of the entanglement is numerically and analytically investigated. We find that thermal effects can enhance disentanglement if the entangled initial state of the central spins does not in the decoherence free space. The critical phenomenon of quantum phase transitions reflected in the disentanglement can be washed out by the thermal effect eventually.

Magnetic-Bottle and Velocity-Map Imaging Photoelectron Spectroscopy of APS-(A=C14H10 or Anthracene):Electron Structure,Spin-Orbit Coupling of APS,and Dipole-Bound State of APS-

Gaseous dibenzo-7-phosphanorbornadiene P-sulfide anions APS （A C14H10 or anthracene） were generated via electrospray ionization, and characterized by magnetic-bottle photoelec- tron spectroscopy, velocity-map imaging （VMI） photoelectron spectroscopy, and quantum chemical calculations. The electron affinity （EA） and spin-orbit （SO） splitting of the APS＂ radical are determined from the photoelectron spectra and Franck-Condon factor simulations to be EA （2.62-4-0.05） eV and SO splitting （43-4-7） meV. VMI photoelectron images show strong and sharp peaks near the detachment threshold with an identical electron kinetic energy （eKE） of 17.9 meV at three different detachment wavelengths, which are therefore assigned to autodetachment from dipole-bound anion states. The B3LYP/6-31＋＋G（d,p） calculations indicate APS has a dipole moment of 3.31 Debye, large enough to support a dipole-bound electron.

Persistent Spin Current in a Hard-Wall Confining Quantum Wire with Weak Dresselhaus Spin-Orbit Coupling

We investigate theoretically the spin current in a quantum wire with weak Dresselhaus spin-orbit coupling connected to two normal conductors. Both the quantum wire and conductors are described by a hard-wall confining potential. Using the electron wave-functions in the quantum wire and a new definition of spin current, we have calculated the elements of linear spin current density j^Ts,xi and j^Ts,yi（i=x, y, z）. We find that the elements j^Ts,xx and j^Ts,yy have a antisymmetrical relation and the element j^Ts,yz has the same amount levelas j^Ts,xx and j^Ts,yy. We also find a net linear spin current density, which has peaks at the center of quantum wire. The net linear spin current can induce a linear electric field, which may imply a way of spin current detection.

Laws of Jet Mixing of the Swirled Flows in a Pipe

Results of experimental research of the mixing process of coaxial flows in a pipe with swirled peripheral jet are presented in this paper. Distribution of temperature and concentration of gases on the axis and wall of the channel under the influence of such factors as the regime flow, ratio of density of flows and swirl degree of the peripheral jet are studied. Research of temperature, swirl angle, circulation in cross sections along with the channel have shown that their distributions have the jet-like character and are described by known dependences for the layer of mixture.

Effect of decoherence from a spin environment on the entanglement dynamics of two-qutrit states

The entanglement dynamics of a two-qutrit system under decoherence from a spin environment is investigated by using negativityas entanglement measure. Our results imply that the entanglement evolution depends not only on the coupling strength and thetunneling elements of the environment but also on the number of the freedom degrees and the initial state of the environment.

Observation of robust edge superconductivity in Fe(Se,Te) under strong magnetic perturbation

The iron-chalcogenide high temperature superconductor Fe(Se,Te)(FST) has been reported to exhibit complex magnetic ordering and nontrivial band topology which may lead to novel superconducting phenomena. However, the recent studies have so far been largely concentrated on its band and spin structures while its mesoscopic electronic and magnetic response, crucial for future device applications, has not been explored experimentally. Here, we used scanning superconducting quantum interference device microscopy for its sensitivity to both local diamagnetic susceptibility and current distribution in order to image the superfluid density and supercurrent in FST. We found that in FST with 10% interstitial Fe,whose magnetic structure was heavily disrupted, bulk superconductivity was significantly suppressed whereas edge still preserved strong superconducting diamagnetism. The edge dominantly carried supercurrent despite of a very long magnetic penetration depth. The temperature dependences of the superfluid density and supercurrent distribution were distinctively different between the edge and the bulk.Our Heisenberg modeling showed that magnetic dopants stabilize anti-ferromagnetic spin correlation along the edge, which may contribute towards its robust superconductivity. Our observations hold implication for FST as potential platforms for topological quantum computation and superconducting spintronics.

Effect of Decoherence Induced by a Spin Environment on Quantum Channel Capacity

We investigate the effect of decoherence from a spin environment on the quantum channel capacity.Our results imply that the time evolution of the quantum channel capacity depends on the number of freedom degrees of the environment,the tunneling element,the initial state of the environment,and the system-environment coupling strength.From the analysis,we find that the strong tunneling elements and the weak coupling strength can enhance the quantum channel capacity while the environment with a large number of freedom degrees and the strong coupling strength will shrink it.