Papers by Keyword: Current Distribution

Abstract: Under the pulse current, the lateral electromagnetic force on the shaped charge jet in the passive electromagnetic protective device is analyzed. Based on the equivalent circuit model, the current distribution model of metal plate is established according to the characteristic of current distribution proposed by Hummer. The lateral transient action model of a shaped charge jet is established based on the Biot Savart law. It is discussed in detail that the magnetic induction B_y of the shaped charge jet between two metal plates and the lateral electromagnetic force f_x on the shaped charge jet varies with time and location. B_y shows U distribution along the jet axial. Before the 37μs, f_x along the jet axial basically is M distribution; the maximum electromagnetic force appears in the distance near the site of the metal plates. After the 37μs, the lateral electromagnetic force along the jet axial basically is U distribution. Prior to 25μs, the total electromagnetic force F_x on the jet is approximately linear increase. In 25μ to 60μs, F_x maintains at a high level. The simulation result is identical with P. Appelgren’s result of static electrically-exploded conductors experiment.

Abstract: Electrodeposition of polycrystalline nickel onto carbon steel substrate has been studied from different types of solutions: (bath I) the Watts nickel plating bath, (bath II) the sulfate-chloride nickel plating bath for production of the SUPER Ni coatings, (bath III) the sulfamate nickel plating bath, and (bath IV) the chloride nickel plating bath. A detailed study has been made on the influence of the bath composition on the mass increment and thickness of the deposited Ni coatings. Cathodic current efficiency of the Ni electrodeposition has been also studied. The electrochemical anodic de-plating technique has been used for measuring the thickness of nickel coatings according to ISO 2177:2003. Evaluation of the effect of bath composition on the quality of the galvanic nickel coatings, was carried out using the Hull cell. In a single test, the range of current densities which provided a desired plating characteristic at a given total current, was previewed. Principles of the electroplating process using the Hull cell have also been explained.

Abstract: The work presents the results of theoretical and experimental investigations of the features and nanodiagnostics probe modes for semiconductors resistivity measurements by current technique of atomic force microscopy and by using test silicon samples with known resistivities (0.01 Ωcm, 1 Ωcm, 5 Ωcm, 10 Ωcm). It is shown that the measured resistivity data in air and in ultrahigh vacuum (10^-8 Pa) is 166 Ωcm and 10 Ωcm, respectively, for the sample with ρ = 10 Ωcm of theoretically predicted resistivity. We showed that reducing of the measurements reliability in air, due to the local anodic oxidation of the substrate surface. Experimental studies of the influence of cantilever load forces (0.3 to 6.0 μN) to the samples surface on the current distribution are presented. Based on the experimental results we developed a mathematical model for determining the resistivity of semiconductor materials by current technique of atomic force microscopy. The results are useful to the development of probe methods for nanoelectronic devices analysis by atomic force microscopy.

Abstract: The galvanic and potential distributions of carbon steel immersed in seawater were studied by wire beam electrode (WBE) technique. Results indicated that the corrosion of carbon steel in seawater tended to local corrosion. With immersion time increasing, local corrosion was more and more serious. During the initial immersion period, the top of the coupon near the water surface was main cathode. With the corrosion extended, corrosion products gradually gathered on the surface of the carbon steel. Potential differences between cathode and anode gradually became small. Cathode and anode redistributed on the surface of carbon steel. At last, the top and the bottom were cathode while the middle was anode. The areas of anode first increased and then decreased. The areas of cathode were in contrast.

Abstract: This paper presents the thoughts about application of composite grid method to solve for current distribution of the dipole.It discusses the basic principle of the method and calculation steps, compares the calculated results with the normal method (FEM) of single set of grid computing , and summarizes the application process and development direction in the future.

Abstract: The effects of additive TN1, power waveforms (full wave, half wave, and direct current), current density and pH on the throwing power of Ni-Co alloy electroforming solution had been investigated by orthogonal tests; and the effects of plating parameters on current distribution of cathode by ANSYS numerical simulation were discussed. The results of orthogonal test showed that the additive TN1 had the largest effect on the throwing power; the power waveform was secondary; the current density and pH had minor effect. The biggest throwing power was 78% when the TN1 was 15g/L and waveform was full wave. Numerical simulation showed that the cathode shape and shield had effect on current distribution; reasonable cathode shape and application of shield could improve the current distribution. The thickness uniformity of part could be up to 92% by optimizing of electrolyte, adjusting the electroforming technics and applying second electroplating.

Abstract: The current distribution on the grid and plate in lead-acid batteries was determined mathematically by using the equivalent circuit method. The grids used in lead-acid batteries are the general lead grids and the 3-D networks grids, respectively. The calculated current distribution on the grid and plate of three-dimension networks lead-acid battery is more uniform than that of general lead-acid battery. To make the current distribution nearly uniform, extended current tabs located between two plate electrodes were proposed, and a sandwich networks plate was formed.

Abstract: Elaborated characterization tools play an important role for the further improvement of solar material and the development of solar cells. Besides the huge variety of highly advanced methods mainly based on optical and electrical measurements, the direct measurement of surface currents by the detection of their induced magnetic fields has gained less attention. The novel method current-analysis-by-inductive-coils (CAIC) based on an inductive coil detector and is reviewed and compared with already established methods, which are light-beam-induced-current (LBIC) and dark-lock-in-thermography (LIT). The detector reveals complementary information at high resolution. The LIT measurements depicted shunting defects in forward and reverse current. Because of the high spatial resolution of the CAIC measurement technique it was determinable that in some cases the positions of current sinks in the CAIC maps are not corresponding with the microstructure. The analyses of the superpositions reveals macroscopic precipitates like SiC and Si₃N₄ filaments and clusters as an origin of some of the shunts.

Abstract: The distributions of corrosion potential and galvanic current of 304 stainless steel under a NaCl droplet were studied by using the wire beam electrode (WBE). It was found that the distributions of the electrochemical parameters were heterogeneous with isolated anodic and cathodic zones appeared randomly. During the corrosion process, the polarity of some anodes changed with the evolution of time. The localized corrosion rate and heterogeneity increased firstly, and then decreased afterward with the increase of time, which can be attributed to the cooperative effects of the aggressive ions and the corrosion products.

Abstract: Since the nucleation of resistance spot welding is a close and invisible process, it is difficult to monitor its nucleation quality reliably. In order to estimate the quality of weld spot, this paper uses magnetic flux density around the nugget to reconstruct the current distribution in the faying surface between two workpiece. In the study, we found the inverse model of welding current and its magnetic flux density around the nugget. Since the model had ill-posedness, the regularization method was required to solve the problem. Conjugate Gradient Method was used to reconstruct the current distribution. The result shows that the image can reflect the main characteristic of current distribution, and it can be used for estimate the quality of weld spot.