External Electric Current Research Articles

Photooxidation Products of Ethanol During Photoelectrochemical Operation Using a Nanocrystalline Titania Anode and a Two Compartment Chemically Biased Cell

Production of hydrogen and/or electricity by photocatalytic treatment of aqueous ethanol solutions has been investigated in a two compartment chemically biased photoelectrochemical cell, employing commercial nanocrystalline Titania as photoanode and Pt as cathode. Results show that hydrogen is produced during photooxidation of ethanol by cathode reduction and by means of a flow of external electric current. The performance of the cell decreased after several hours of operation, most possibly due to the formation of hydrocarbons of higher molecular weight. This is contrary to simple photocatalytic ethanol oxidation where complete mineralization of alcohol is observed.

자기점서유체 댐퍼 코어의 최적화 설계를 위한 전자기장 해석

외부에서 인가되는 전류의 세기에 따라 결합력의 세기가 달라지는 자기점성유체의 특성을 이용한 자기점성 유체 댐퍼는 유체의 결합력을 통해 전단력을 발생시켜 진동의 제어가 가능하다. 자기점성유체 댐퍼의 성능을 좌우 하는 코일 작동부의 최적화를 위해 유한요소해석을 이용해 코일 형상에 따른 전자기력의 성능비교를 실시하였다. 또한 고효율 댐퍼를 제작하기 위한 방법으로 다단의 코일 작동부를 가지는 댐퍼를 제안하였으며, 기존의 댐퍼와의 전자기적 성능 비교를 통해 댐퍼의 성능 비교를 수행하고 제한된 조건에서 최대의 효과를 가질 수 있는 방안을 제시하고 그에 따른 전자기장 해석을 수행하였다. The magneto-rheological fluid expresses different cohesiveness according to the strength of the external electric current. The magneto-rheological fluid damper, which uses such characteristics of the fluid, generates shear force due to the fluid's cohesiveness. The core can be said to determine the magneto-rheological fluid damper's performance. This study uses the finite element analysis to compare the performance of different electromagnetic forces, which are affected by the shapes of the coil, and thus to find the optimum design for the core. In addition, as a step to construct a high-efficient damper, we suggest a type of damper that can control multiple coils and compares the performance of this damper and that of the standard damper by comparing the performance of their electro-magnetic fields.

Development of electrochemical cell with layered composite of the Gd-doped ceria/electronic conductor system for generation of H 2–CO fuel through oxidation–reduction of CH 4–CO 2 mixed gases

This paper shows the recent results on the development of layered composite promoting two types of electrochemical reactions (oxidation and reduction) in one cell. This cell consisted of porous Ni–Gd-doped (GDC) ceria cathode/thin porous GDC electrolyte (50 μm)/porous SrRuO 3–GDC anode. The external electric current was flowed in this cell at the electric field strength of 1.25 and 6.25 V/cm. The mixed gases of CH 4 (30–70%) and CO 2 (70–30%) were fed at the rate of 50 ml/min to the cell heated at 400–800 °C under the electric field. In the cathode, CO 2 was reduced to CO (CO 2 + 2e − → CO + O 2−) and the formed CO and O 2− ions were transported to the anode through the pores and surface and interior of grains of GDC film. On the other hand, CH 4 was oxidized in the anode to form CO and H 2 through the reaction with diffusing O 2− ions (CH 4 + O 2− → CO + 2H 2 + 2e −). As a result, H 2–CO mixed fuel was produced from the CH 4–CO 2 mixed gases (CH 4 + CO 2 → 2H 2 + 2CO). This electrochemical reaction proceeded completely at 800 °C and no blockage of gases was measured for long time (>10 h). Only H 2–CO fuel was generated in the wide gas compositions of starting CH 4–CO 2 gases.

Instabilities in the flow past localized magnetic fields

The flow in a shallow layer of an electrically conducting fluid past a localized magnetic field is analyzed numerically. The field occupies only a small fraction of the total flow domain and resemblances the magnetic field created by a permanent magnet located close to the fluid layer. Two different physical cases are considered. In the first one, the fluid layer is free from externally injected electric currents, therefore, only induced currents are present. In the second case, an external electric current is injected to the fluid layer, transversally to the main flow direction. It is shown that the Lorentz force created by the interaction of the electric currents with the non-uniform magnetic field acts as an obstacle for the flow and creates different flow patterns similar to those observed in the flow past bluff bodies. A quasi-two-dimensional model that takes into account the existence of the bottom wall through a linear Hartmann-Rayleigh friction term is considered. When inertial and magnetic forces are strong enough, the wake formed behind the zone of high magnetic field is destabilized and a periodic vortex shedding similar to the classical von Kármán street is found. The effect of Hartmann-Rayleigh friction in the emergence of the instability is analyzed.

A model of a soliton-memory element based on a semiconductor superlattice

A new type of memory element that records data in the form of electromagnetic solitons is proposed. A semiconductor superlattice serves as a nonlinear medium. The solitons propagating along the layers of the superlattice are used for recording. Information is stored in cells, each of which is bounded by two transverse heterogeneous layers. Writing and reading of a soliton are performed using an external electric current that is activated inside a given cell.

Theoretical model of DC electric field formation in the ionosphere stimulated by seismic activity

Seismic activity is accompanied by emanation of soil gases into the atmosphere. These gases transfer positive and negative charged aerosols. Atmospheric convection of charged aerosols forms external electric current, which works as a source of perturbation in the atmosphere–ionosphere electric circuit. It is shown that DC electric field generated in the ionosphere by this current reaches up to 10 mV/m, while the long-term vertical electric field disturbances near the Earth's surface do not exceed 100 V/m. Such a limitation of the near-ground field is caused by the formation of potential barrier for charged particles at the Earth's surface in a process of their transport from soil to atmosphere. This paper presents the method for calculation of the electric field in the atmosphere and the ionosphere generated by given distribution of external electric current in the atmosphere.

Possible DC electric field in the ionosphere related to seismicity

This paper presents the method for calculation of DC electric field in the atmosphere and the ionosphere generated by model distribution of external electric current in the lower atmosphere. Appearance of such current is associated with enhancement of seismic activity that is accompanied by emanation of soil gases into the atmosphere. These gases transfer positive and negative charged aerosols. Atmospheric convection of charged aerosols forms external electric current, which works as a source of conductivity current in the atmosphere–ionosphere electric circuit. It is shown that DC electric field generated in the ionosphere by this current reaches up to 10 mV/m, while the long-term vertical electric field disturbances excited near the Earth surface do not exceed 100 V/m. Such limitation of the near-ground field is caused by the formation of potential barrier for charged particles at the Earth surface in a process of their transport from soil to atmosphere.

First-principle study on structures and electronic properties of aluminum nanowire wrapped in carbon nanotube

We have carried out first-principle calculations of simple models for Al nanowire wrapped in carbon nanotube and have investigated the electronic properties of them based on the regional density functional theory. For both the (8,0) zigzag nanotube-wrapped and the (4,4) armchair nanotube-wrapped Al nanowire models, the nanowire with a monoatomic thickness is stabilized just on the center axis of the carbon nanotube due to a shortage of the tube radius. The microscopic image that electrons in the Al nanowire interact with the electrons in the nanotube on every side is obtained clearly in terms of the quantum energy densities. Band structures of the nanotube-wrapped Al nanowire models represent the conductivity along the wire, where bands originated from the Al atom raise and cross the Fermi level for each model. We have confirmed that reversible hydrogen storage processes are realized in our model. Under the external electric field and current, the effective charge tensor density of the Al atom has been computed using the non-relativistic limit of quantum electrodynamics.

Effect of electric current on the evolution of plastic strain near a crack tip

The effect of direct current on the evolution of plastic strain near the tip of a crack in a crystal in tension is studied. The plastic strain near the crack tip in the loaded specimen is the result of motion of dislocations in the active slip planes of the crystal under the action of shear stresses caused by external loading and electric current. The Joule heat, Thomson effect, and “electron wind” (electroplastic effect) are taken into account in calculations. The plastic strain and stress distributions near the crack tip are determined at different moments of time for a given magnitude ofelectric current. The effect of the plastic zone on the stress‐intensity factor of the crack is studied. It is found that the plastic strain is affected largely by the Joule heat released upon passage of the electric current. A numerical analysis is performed for an α‐Fe crystal.

Constant electric field of human beings and its role in medicine.

An investigation was made of fundamental biophysical principles of the intrinsic electric system functioning in different conditions. This system was shown to govern the vital functions of separate cells and of the entire live organism. We developed a method enabling the correction of an affected intrinisic electric system. This method is based on the application of an external electric current.

Stimulation of tobacco shoot regeneration by alternating weak electric field

Nicotiana tabacum morphogenetic callus was used to study the stimulative effects of external alternating electric currents of low level and low frequency on the cytodifferentiation processes. The N. tabacum calli were grown on standard medium for shoot regeneration and subjected to electric currents (50 Hz, 0.1–50 μA) during the whole period of treatment (30 days). The number of shoots, total mass, DNA and protein content were measured for each callus sample at the end of the experiment. The number of shoots increased by up to 300% for the samples stimulated with 50 μA although no significant changes were noted in total mass, DNA and protein content in the stimulated samples compared to control. We suggest that in the presence of the external electric current, the callus cells become more sensitive to chemical signals (hormones and/or ions) in the culture medium. A series of changes in the activity of membrane components, as a consequence of the modulation of membrane potential by the external electric field, could support our hypothesis.

A direct current piezoelectric effect in fluorinated ethylene-propylene copolymer due to space charge

A dc piezoelectric effect was observed in corona charged fluorinated ethylene-propylene membranes. After an appropriate thermal treatment the charge deposited on the sample surface penetrated the bulk material, with the charge centroid remaining at the center of the sample was indicated by heat pulse measurements. The charged sample responded to an applied pressure with a constant voltage signal or, if in short circuit, with a transient external electric current. This phenomenon was interpreted as being caused by a relative movement of the stored charges with respect to the material structure. A semiquantitative analysis based on this relative movement was carried out that allowed physical parameters such as the volumetric charge density and the longitudinal piezoelectric coefficient to be obtained.

Periodic Coexistence of Superconductivity with Magnetic Order

A new type of solution is found of the one-dimensional Ginzburg-Landau equation for superconducting pairing gap Δ( x ) coupled with magnetization M ( x ). It describes a periodic coexistence of superconductivity and magnetic order realized in an open system, which is stabilized by external electric current. Within a spatial period of this phase, d ∼(8π 2 c / a 0 ) 1/2 ( T M - T ) -1/2 , there appears a pair of magnetic domain walls at x = d /4 and 3 d /4, where Δ( x ) reaches its maxima. A novel feature is that such an order is induced and controlled by the electric current supplied from the external device, j , defining another order parameter related to the phase factor of the gap, \(\zeta =mj/\hbar e\sim (4\alpha^{3}_{0}/27\beta^{2}\gamma )^{1/2} (T_{\rm c}-T)^{3/2}\).

First-principles mesoscopic dynamics in heterogeneous materials

A systematic link between microscopic and macroscopic theories of matter has been lacking in the case of heterogeneous materials (polycrystals, composites, etc.). The properties of such materials are largely determined by their collective microstructure, which defines several intermediate or mesoscopic length scales. A microscopic description is presented and the principles of statistical mechanics are used to derive a set of mesoscopic field dynamical equations that describe microstructure evolution under external stresses, temperature gradients, or electric current. The macroscopic dynamical equations of continuum mechanics are recovered. The cross-coupled phenomena of elastic deformations and inelastic diffusive and slip processes are present, setting the stage for a first-principles theory of dislocation dynamics and plasticity.

Thermomagnetic Effects in the Mixed State of Type II Superconductors

A phenomenological theory is developed for the thermomagnetic effects in the flux flow state of type II superconductors. Ettinghausen-, Nernst-, and Righi-Leduc-coefficients are expressed explicitly with the use of known physical quantities. Thermal conductivity and analogous Peltier coefficient due to flux line are discussed in detail using a quasi-particle model for the flux line. It is shown that the analogous thermoelectric figure of merit in the flux flow states has large values of the order of 1/T in the perpendicular direction to the external electric current, while it is of the order of 10-2/T∼10-3/T in the direction parallel to the current. A possibility of a negative figure of merit is also pointed out.

I. On some relations of chemical corrosion to voltaic current

The chief object of this research was to ascertain the amounts of voltaic current produced by the chemical corrosion of known weights of various metals in different liquids. The research was also made to throw light upon the conditions which determine the entire conversion of potential molecular energy into external ( i. e ., available) electric current. The method adopted was to take about six or eight ounces by measure of a corrosive electrolyte and divide it into two equal volumes in two similar glass vessels. Two pieces of metal of equal dimensions were then cut from the same sheet, cleaned perfectly, and weighed. One of the pieces was employed as the positive plate of a voltaic cell in one of the portions of liquid, and the other as a comparison corrosion, sheet in the other portion. The negative metal of the voltaic cell was in nearly all cases a large cylinder of sheet platinum, and surrounded the positive one. The positive and comparison plates were wholly immersed in the separate portions of liquid, except that the former had a narrow exterior projecting strip for connexion in a circuit. The current from the cell was passed by means of a small sheet silver anode inch (½ inch by ¾ inch), and a smaller silver cathode (¼ inch by 3/8 inch) in a third vessel, through a cyanide of silver plating solution containing the least practicable proportion of free potassic cyanide in order to obtain the maximum amount of silver deposit. During each experiment observations were made of any liberation of gas or formation of solid coating upon the plates, and of any other circumstance which appeared likely to affect the speed of corrosion, or weight of the plates, or of the deposited silver; and in any case where any solid coating was found, it was entirely removed after the experiment, and previous to ascertaining the losses of weight by corrosion. After the experiment the plates were well washed and carefully dried between hot sheets of filter-paper before weighing. The metals and liquids employed were as pure as could conveniently be obtained, and distilled water was used for all the solutions. The sample of potassic cyanide usually employed was found by analysis to contain 89.14 per cent, of the actual substance. Nearly all the liquids were at the atmospheric temperature, and in nearly every case the comparison sheet was employed.