Electrochemical studies of liquid 4-cyanopyridine (4-CNPy; melting point = 78 °C) are reported. In solutions containing only tetra-fl-butylammonium perchlorate (TBAP) as supporting electrolyte, 9.6 M 4-CNPy can be reduced at a steady-state mass-transport rate (10 A/cm1 2 34) yielding a highly concentrated solution layer of the product, TBA+-4-CNPy'", adjacent to the electrode surface. The transient voltammetric response is distorted by the slow coupled diffusion/migration of the supporting electrolyte cation (TBA+) necessary to maintain electroneutrality within this layer. Transport-related phenomena unique to concentrated solutions are presented and discussed with regard to the observed electrochemical behavior of 4-CNPy. These include the effects of (1) counterion dilution and migration, (2) fluid convection induced by interdiffusion of reactant (4-CNPy) and product (4-CNPy'"), and (3) concentration-dependent diffusivities. General flux equations (diffusion, migration, and convection) are presented in terms of the partial molar volumes of each solution component for a constant density fluid.A theoretical analysis of the current-dependent ohmic solution resistance, Rfi), at a spherical electrode is also presented for the special case where the concentration of supporting electrolyte is significantly less than the redox active species. This current-dependent resistance generates a 200 V/cm electrical potential gradient, d
Abstract-This paper proposes a new synthetic jet actuation concept for small, low speed, highly maneuverable AUVs. Synthetic jet thrusters, which produce jets of vortex rings, are inspired by the pulsatile jet propulsion of salps, jellyfish, and squid. To assess the potential utility of this scheme, we developed synthetic jet actuator prototypes, and verified their function via both force measurement and flow visualization experiments. We used a genetic-algorithm based technique for optimizing the actuation profile of the thrusters. Also presented is an initial discussion of vehicle design. Our conclusion is that synthetic jet thrusters are a viable propulsion method for small underwater vehicles.
This paper reports on the analysis and evaluation of different automobile traction concepts of an electrically powered compact class vehicle equipped with an energy converting fuel cell system. All simulation models of the fuel cell cars are based on an on-board gasoline reformer unit. As fuel cell systems both a solid oxide fuel cell (SOFC) and a polymer electrolyte membrane fuel cell (PEMFC) are compared. For a study of the influence of the energy management concept on system performance, the fuel cell car is eventually equipped with an auxiliary energy buffering battery. A variety of studies are shown concerning the performance and energy consumption of the different systems as well as sensitivity studies for selected system parameters.losses due to the charging and discharging currents.
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