Development of Calculation Model of the Distribution of Protective Currents of Gas Pipeline Electrochemical Protection System in Permafrost Soils

Clarification of parameters of the distribution of protective currents in permafrost soils is an urgent issue. The article describes a grid model of the soil, which differs from the generally accepted homogeneous model. Grid model of soil imitates various conditions of permafrost. Calculation model allows us to estimate parameters of the electrochemical protection of gas pipelines, taking into account the inequality of the parameters of the electrical conductivity of soils and also the transition resistance of the protective coating of the pipes along the length of the section. The model also makes it possible to estimate seasonal changes in the propagation conditions of protection currents due to periodic thawing and freezing of the soil in the conduction layer.

Development of a Current Collector with a Graphene Thin Film for a Proton Exchange Membrane Fuel Cell Module

This paper constructs planar-type graphene thin film current collectors for proton exchange membrane fuel cells (PEMFCs). The present planar-type current collector adopts FR-4 as the substrate and coats a copper thin film using thermal evaporation for the electric-conduction layer. A graphene thin film is then coated onto the current collector to prevent corrosion due to electrochemical reactions. Three different coating techniques are conducted and compared: Spin coating, RF magnetron sputtering, and screen printing. The corrosion rates and surface resistances are tested and compared for the different coating techniques. Single cell PEMFCs with the developed current collectors are assembled and tested. A PEMFC module with two cells is also designed and constructed. The cell performances are measured to investigate the device feasibility.

Ropy foam-like TiO2 film grown by water-based process for electron-conduction layer of perovskite solar cells

ABSTRACTSelf-assembled TiO2 foam-like films, were grown by the water based Streaming Process for Electrodeless Electrochemical Deposition (SPEED). The morphology of the ∼1 µm thick films consists of a tangled ropy structure with individual strands of ∼200 nm diameter and open pores of 0.1 to 3 micron dimensions. Such films are advantageous for proposed perovskite solar cell comprising CH3NH3PbI3 absorber with additional inorganic films as contact and conduction layers, all deposited by SPEED. Lateral film resistivity is in the range 20 – 200 kΩ-cm, increasing with growth temperature, while sheet resistance is in the range 2 – 20 x 108 Ω/Sq. X-ray diffraction confirms presence of TiO2 crystals of orthorhombic class (Brookite). UV-vis spectroscopy shows high transmission below the expected 3.2 eV TiO2 bandgap. Transmittance increases with growth temperature.

On the structural integrity of the spinel block in the β"-alumina structure

The β′′-alumina structure is examined in detail and an analysis is presented of the three-dimensional integrity of the lattice. The layer structure that is responsible for the very high sodium conduction rate is the specific focus. Rigid layers that are derived from the cubic spinel structure are interleaved by more open honeycomb pathways where rapid ion diffusion takes place. The three-dimensional rigidity of the spinel block in this structure makes it possible to accurately quantify the conduction layer thickness based only on the hexagonal unit-cell dimensions, as suggested originally by Harbach [(1983), J. Mater. Sci. 18, 2437–2452]. His calculation is tested rigorously against the many single-crystal structure determinations that have been made on the β′′-alumina family compounds and excellent correlation is found.

A Threshold Voltage Simulation of Hydrogen-Terminated Diamond MESFETs

In this paper, the threshold voltage of diamond film-based metal-semiconductor field effect transistors (MESFETs) has been simulated using Silvaco TCAD tools. The drain current (Id) versus gate voltage (Vg) relationship, and the distribution of acceptors in diamond surface conduction layer were also investigated. From the simulation results, it was found that the gate length contributed the most to the threshold voltage, while the doping depth almost had no impact on the threshold voltage value.