240kA铝电解槽电热场测试与分析

对某公司3台240kA铝电解槽进行了电热场和能量平衡技术测试,评价了进电母线断面的选择、电流分配、能量支出的合理性,为改善生产工艺技术条件提供了依据。     

Mechanisms of electrical coupling between pyramidal cells

Direct electrical coupling between neurons can be the result of both electrotonic current transfer through gap junctions and extracellular fields. Intracellular recordings from CA1 pyramidal neurons of rat hippocampal slices showed two different types of small-amplitude coupling potentials: short-duration (5 ms) biphasic spikelets, which resembled differentiated action potentials and long-duration (>20 ms) monophasic potentials. A three-dimensional morphological model of a pyramidal cell was employed to determine the extracellular field produced by a neuron and its effect on a nearby neuron resulting from both gap junctional and electric field coupling. Computations were performed with a novel formulation of the boundary element method that employs triangular elements to discretize the soma and cylindrical elements to discretize the dendrites. An analytic formula was derived to aid in computations involving cylindrical elements. Simulation results were compared with biological recordings of intracellular potentials and spikelets. Field effects produced waveforms resembling spikelets although of smaller magnitude than those recorded in vitro. Gap junctional electrotonic connections produced waveforms resembling small-amplitude excitatory postsynaptic potentials. Intracellular electrode measurements were found inadequate for ascertaining membrane events because of externally applied electric fields. The transmembrane voltage induced by the electric field was highly spatially dependent in polarity and wave shape, as well as being an order of magnitude larger than activity measured at the electrode. Membrane voltages because of electrotonic current injection across gap junctions were essentially constant over the cell and were accurately depicted by the electrode. The effects of several parameters were investigated: 1) decreasing the ratio of intra to extracellular conductivity reduced the field effects; 2) the tree structure had a major impact on the intracellular potential; 3) placing the gap junction in the dendrites introduced a time delay in the gap junctional mediated electrotonic potential, as well as deceasing the potential recorded by the somatic electrode; and 4) field effects decayed to one-half of their maximum strength at a cell separation of approximately 20 micron. Results indicate that the in vitro measured spikelets are unlikely to be mediated by gap junctions and that a spikelet produced by the electric field of a single source cell has the same waveshape as the measured spikelet but with a much smaller amplitude. It is hypothesized that spikelets are a manifestation of the simultaneous electric field effects from several local cells whose action potential firing is synchronized.     

大圆坯连铸结晶器内电磁场分布特性的实验研究

在马钢工业生产条件下,用高斯计空载测量Φ380 mm圆坯连铸结晶器内在电流参数400~510A、2.0~2.5 Hz的范围内磁感应强度的分布特性。结果表明,结晶器中心垂直方向磁感应强度变化曲线呈波峰状,在离结晶器上口约530 mm的电磁搅拌器中心处有最大值;在结晶器水平截面上磁感应强度沿截面中心至边缘逐渐增大。钢液弯月面处的磁感应强度是结晶器中心最大值的10%左右。马钢在现有生产条件下采用400 A/2.5 Hz的电流参数,相应电磁搅拌强度明显偏低。     

面向风电消纳的铝电解槽电磁场特性研究

针对铝电解消纳风电过程中物理场将发生非线性变化的现状,建立针对消纳风电的铝电解槽电磁场模型,并开展了消纳电流为设计电流的25%、20%、15%、10%和5%五种情况下的电磁场计算。结果表明,槽电压随着消纳的幅度增加而增加,同时铝液层水平电流密度亦存在相应变化,但电场整体趋势未变,各部分压降均在合理水平;此外,随着消纳风电量的增加,槽内磁场极值与均值都会相应增加,但整体的磁场分布规律未发生大幅波动,电解槽依然可以维持在稳定状态,从而保证在消纳风电过程中,电解槽内磁流体的稳定性,为其平稳消纳提供先天条件。     

Heredity of Aluminum Melt by Electric Pulse Modification (Ⅱ)

 Heredity of high pure aluminum melts under different pulse electric field was investigated by means of repetitious remelt experiment. The results indicate that the genetic coefficient by measurement of grain size of cast structure has a close relation with pulse voltage. Moreover, the hereditary law accords with the function of In=1+e-αn+β. The stability of genetic carrier (cluster) comprises in the competition between repetitious cooling and heating impulse and the effect of electric pulse modification.     

Cutoff Frequencies for Impulse Response Tests of Existing Foundations

The impulse response test is a nondestructive evaluation technique commonly used for quality control of driven concrete piles and drilled shafts where the pile heads are accessible. When evaluating existing foundations, the presence of a pile cap or other structure makes the pile heads inaccessible and introduces uncertainties in the interpretation of impulse response results. A test section was constructed at the National Geotechnical Experimentation Site (NGES) at Northwestern University to examine the applicability of nondestructive testing methods in evaluating deep foundations under inaccessible-head conditions. This paper focuses on the results of impulse response tests conducted atop the three pile caps at the NGES. Based on field experimentation and numerical simulations, a frequency was determined below which the impulse response test could be used for inaccessible-head conditions. This cutoff frequency primarily depends upon the geometry of the pile cap and pile. A case study is presented that describes impulse response tests obtained on a number of drilled shafts both after the shaft was constructed and after grade beams and walls were built. The results of these tests also follow the trends observed in the NGES tests related to cutoff frequency.     

某铀尾矿中U、Th在电场作用下释放及迁移规律

以电流场作为核素迁移的载体,研究某铀尾矿中U、Th在0、0.5、1.0、1.5V/cm直流电场条件下的释放及迁移规律。结果表明,在添加电场时,铀元素的浸出量小于自然淋滤条件下的浸出量,但土壤对铀的释放能力明显提升,且电场强度越强,释放能力越强,而钍元素则受其影响不大。在0、0.5、1.0、1.5V/cm电场强度条件下铀元素的累积浸出量分别为1.439、1.285、1.474、1.795mg/L,说明电场强度对U的释放以及迁移有促进作用。铀元素在电场作用下的迁移规律和其他重金属元素的规律类似,都是阳极往阴极迁移,且电场强度越大,阳极附近富集的铀元素浓度越高。     

Heredity of Aluminum Melt by Electric Pulse Modification (II)

Heredity of high pure aluminum melts under different pulse electric field was investigated by means of repetitious remelt experiment. The results indicate that the genetic coefficient by measurement of grain size of cast structure has a close relation with pulse voltage. Moreover, the hereditary law accords with the function of I_n = 1 + e^−αn+β. The stability of genetic carrier (cluster) comprises in the competition between repetitious cooling and heating impulse and the effect of electric pulse modification.     

高压电力电缆故障点查找定位

在原有低压脉冲显示设备的基础上，改低压脉冲返回信号为用高压直流放电返回信号，可以得到直观，无干扰的波形，采用高压直闪电缆故障定点法替代原低压脉冲法，能够准确，快速地查找高压电力电缆故障。     

Electroporation of, plasmid isolation from and plasmid conservation in Clostridium acetobutylicum DSM 792

Procedures have been developed allowing recombinant DNA work with Clostridium acetobutylicum DSM 792. Electroporation was used to introduce plasmid DNA into exponentially growing clostridial cells and 6 x 10(2) transformants/microgram DNA could be obtained at a time constant of 5.5 ms, 1.8 kV, 50 microF, and 600 omega. The method also allowed the taxonomic group IV strain NI-4082 to be transformed (10(1) transformants/microgram DNA). Plasmid preparation from recombinant clostridia was optimal when a modification of the alkaline lysis method was employed. It was also important to use cells from the mid-logarithmic growth phase. Recombinant strains could be easily preserved as spore suspensions; under all conditions tested plasmids were maintained.     

Field emission from one-dimensional single-crystalline NdB6 nanowires

A facile catalysis-free method was utilized to synthesize functional neodymium hexaboride (NdB6 ) nanowires of single crystal using Nd powders and BCl 3 as starting materials. The XRD pattern confirmed that a single phase NdB 6 could be obtained. Raman-spectra elucidated the active vibrational modes of the hexaborides. The TEM images clearly showed that the hexaborides were submicron in size with a cubic morphology. The field emission of these one-dimensional NdB6 nanowires showed a low field emission turn-on (5.55 V/μm at a current density of 10 μA/cm2 ), and high current density with a field enhancement factor of 1037. The emission current density and the electric field followed the Fowler-Nordheim (F-N) relationship. The good performance for field emission was attributed to the single-crystalline structure and the nanowire geometry.     

电流脉冲对普通螺纹钢凝固组织的影响

 研究了高熔点的20MnSi螺纹钢电脉冲处理后的微观组织。结果表明，电脉冲处理后的凝固组织中铁素体和珠光体的分布更加均匀，原来严重的魏氏组织和块状的先共析铁素体消失了。定性讨论了电脉冲影响凝固组织的可能作用机理。     

基于电热场耦合条件下稀土电解槽电极结构优化模拟

以3kA钕电解槽为研究模型,考虑到电热场在电解过程中的相互影响,运用COMSOL有限元模拟软件建立了的电热耦合模型,并对不同配比的电极插入深度、极间距进行仿真模拟。结果表明,在一定槽电压下,电极插入深度与极间距之间存在配比关系,配比关系影响电流和温度分布。电热场耦合后,在4.2V槽电压下,电极插入深度为220 mm、极间距75 mm时的电流效率较高,电解过程更加稳定。     

Induced piezoelectricity in isotropic biomaterial

Isotropic material can be made to exhibit piezoelectric effects by the application of a constant electric field. For insulators, the piezoelectric strain constant is proportional to the applied electric field and for semiconductors, an additional out-of-phase component of piezoelectricity is proportional to the electric current density in the sample. The two induced coefficients are proportional to the strain-dependent dielectric constant (depsilon/dS + epsilon) and resistivity (drho/dS - rho), respectively. The latter is more important at frequencies such that rhoepsilonomega less than 1, often the case in biopolymers. Signals from induced piezoelectricity in nature may be larger than those from true piezoelectricity.     

Mechanism of human blood neutrophil activation by electric field pulses

High voltage electric field pulses, was shown previously, induced activation of blood neutrophil respiratory burst, registered as increase in luminol-dependent chemiluminescence of cell suspension. The quantitative analysis of this phenomenon by fluorescent probes and radioisotope methods have shown that electric pulse induced neutrophil chemiluminescence is a result of Ca2+ ions entering the cells through reversible pores in plasma membrane. Electric pulse of amplitude 5 kV/cm generates two tens of reversible pores with average diameter nearly 2 nm and lifetime 1 minute. Total amount of calcium penetrating at this conditions from the medium (1 mM Ca2+) into the cells was as high as 1.2 fmole/cell that is nearly 3.6 mM concentration per cell volume. Whereas the increase in the cytoplasmic concentration of free calcium did not exceed 1.3 microM, that is more then 3 order less. Data presented is discussed with relation to possible biological role of electroporation by natural electric fields presented in living systems.     

镝铁阴极电蚀对稀土电解槽的电解特性影响分析

随着稀土熔盐电解槽电解过程的进行,阴极形状会随着时间的推移发生电腐蚀,电解槽底部阴极锥角α不断增大,对电解效率与热场产生了一定影响.以越南镝铁阴极稀土电解槽为研究对象,利用COMSOL多物理场耦合软件,计算了稀土电解槽中阴极不同电解阶段不同阴极形状的电解特性参数,得到了电解槽中不同阴极锥角α值与最大电流密度关系曲线图,并分析了电解槽内阴极电蚀对整个电解反应过程的影响,为电解槽的后期维护提供了参考依据.      

The use of combined methods of magnetoelectrotherapy in treating polyneuropathies

A comparative evaluation by such parameters as alleviation of pain syndrome, improvement of peripheral resistance and vegetotrophic processes, a decline in pareses and sensory disorders has been performed in 3 groups of patients: group 1 underwent benzohexonium electrophoresis, group 2 benzohexonium electrophoresis in the magnetic field produced by the unit "Polyus-I" followed by low-frequency electrotherapy with bipolar impulse current, group 3 benzohexonium electrophoresis in the magnetic field from the unit "ADMT-Magnipuls" followed by low-frequency electrotherapy with bipolar impulse current. The best clinical and physiological results were reported in group 3 patients.     

Scanning electron microscopy of in vitro chemically transformed mouse embryo cells

A cloned nontumorigenic control cell line of C3H mouse embryo cells (C3H/1OT1/2CL8) and two cell lines derived from it by treatment in vitro with 7,12-dimethylbenz(a)anthracene (DMBA) or 3-methylcholanthrene (MCA) were studied by scanning electron microscopy. Confluent control cells were polygonal in shape and extensively flattened with smooth surfaces. Both in vitro transformants were pleomorphic to fusiform in shape, thicker than the control cells, and lacked contact inhibition. Microvilli of variable length and small marginal ruffles were characteristic surface alterations of the MCA-transformed cells, while blebs and numerous cytoplasmic strands extending between cells were typical of the DMBA transformant. Inoculation of the DMBA-transformed cells into C3H mice and re-establishment of cells from one of the subsequent fibrosarcomas in culture revealed an increased number of microvilli on the surface of the cells and an alteration in growth pattern. Other surface characteristics remained the same. A possible relationship between surface topography and outer membrane glycolipids is discussed.     

电场强化锰矿尾矿湿法浸出行为研究

随着锰产业的迅锰发展,国内高品位锰矿逐渐枯竭,有必要探索锰矿尾矿资源化利用技术。实验采用电场强化锰矿尾矿的湿法浸出过程,并探索其强化机理。通过C射线衍射（XRD）、X射线荧光分析（XRF）、扫描电镜（SEM）以及紫外可见漫反射光谱（UV—visDRS）等检测方法,分析了碳酸锰矿尾矿的结构和成分,以及浸出反应前后的物相变化行为,研究了强化浸出工艺条件。结果表明,电场可改变矿浆颗粒表面电荷分布,强化锰矿尾矿浸出过程。在电流密度为5000A／m^2、液固比6：1mL／g、矿酸比为1：0．7、温度为60℃、时间为1h时,锰浸出率可达94．23％,与同等条件不加电场时相比提高18％,尾矿锰含量由4．33％降到0．14％。     

Mathematical modeling of a direct current electric arc: Part I. Analysis of the characteristics of a direct current arc

A mathematical model is used to describe fluid-flow, heat-transfer, and electromagnetic phenomena in the arc region of a direct current electric arc furnace (DC EAF). Based on those model results, a detailed physical analysis of the arc was performed, where the numerical computations help to explain the arc structure, its behavior, and the highly coupled relationship among their main physical variables. This analysis leads to the conclusion that the arc behaves in such a way that all the arc characteristics are controlled by the expansion of the arc, which is the main feature used to physically describe the arc behavior. The arc expansion is evident from the arc shape, which is defined as the region where conduction of electricity takes place. The arc shape is clearly seen in several contour fields presented in this work, such as the current density, the magnetic flux density, the electric conductivity, the electric potential, and the temperature fields. The results of this article focus on process analysis, to provide insight into the inter-relationship among the arc variables, and to establish physical grounds to subsequently explore dimensionless analytical representations to describe the arc behavior.