A State Observer Design for Simultaneous Estimation of Charge State and Crossover in Self-Discharging Disproportionation Redox Flow Batteries

This paper presents an augmented state observer design for the simultaneous estimation of charge state and crossover flux in disproportionation redox flow batteries, which exhibits exponential estimation error convergence to a bounded residual set. The crossover flux of vanadium through the porous separator is considered as an unknown function of the battery states, model-approximated as the output of a persistently excited linear system. This parametric model and the simple isothermal lumped parameter model of the battery are combined to form an augmented space state representation suitable for the observer design, which is carried out via Lyapunov stability theory including the error-uncertainty involved in the approximation of the crossover flux. The observer gain is calculated by solving a polytopic linear matrix inequality problem via convex optimization. The performance of this design is evaluated with a laboratory flow battery prototype undergoing self-discharge.Comment: arXiv admin note: text overlap with arXiv:1903.0407

Spatial Variation in the Rates of Unemployment in Ohio By County, January 1981-July 1982

Author Institution: Department of Geography, University of AkronSpatial patterns of unemployment by county in Ohio are analyzed using quarterly labor statistics from January 1981 to July 1982. A cluster analysis grouped the 88 counties into 3 primary regions, 2 secondary groups, and 3 outlier counties. Eighty of the counties lie in the 3 primary groups, which are characterized as low, average, and high unemployment areas in relation to the statewide trend in unemployment during this period. Counties in the low unemployment group have a diversified economy and are generally located in the central corridor of Ohio extending from Cincinnati to Cleveland. Counties in the high unemployment region are located primarily in southern Ohio and contain a rural population with a high level of poverty. The county unemployment rates are also correlated with the percentage of employment concentrated in the major economic sectors. The manufacturing and agricultural sectors show positive correlations to unemployment, whereas finance, insurance, and real estate (F.I.R.E.), services, and trade show strong negative correlation

The protagonists of John Updike

My purpose in this paper is to show that the protagonists of Updike can be categorized into groups and that these protagonists are as real for me as they are for Updike. It is because of these protagonists that the works of Updike will live for many years to come

Development of a Spacecraft Antenna Pointing Gimbal

The development of the pointing gimbal in the high-gain antenna system (HGAS) of the Solar Dynamics Observatory spacecraft is described. The gimbal was designed for 5 years of service in Geo-Synchronous orbit. The hardware incorporates multiple levels of redundancy, allows harnessing and waveguide along its full length across its two axes of rotation and points with an accuracy of better than 0.065 . Significant issues with actuator alignment, Electrical Contact Ring noise, pointing budget, and waveguide failures are described, along with their respective resolution

Development of cable drive systems for an automated assembly project

In a robotic assembly project, a method was needed to accurately position a robot and a structure which the robot was to assemble. The requirements for high precision and relatively long travel distances dictated the use of cable drive systems. The design of the mechanisms used in translating the robot and in rotating the assembly under construction is discussed. The design criteria are discussed, and the effect of particular requirements on the design is noted. Finally, the measured performance of the completed mechanism is compared with design requirements

Drivers of membrane fouling in the vanadium acetylacetonate flow battery

Vanadium acetylacetonate (V(acac)3) disproportionation electrochemistry promises a crossover-tolerant, high-voltage flow battery, but exhibits low efficiency and short cycle life. We show that membrane fouling, rather than a parasitic side reaction, dominates early performance fade. Crossover rates through porous membranes were estimated from voltage transients with an adaptive observer while cycling flow-through reactors. For 0.1M V(acac)3 and 0.3M TEABF4 in acetonitrile flowed countercurrently at 5.0cms−1 parallel to the separator, fresh Daramic 175 and Celgard 4650 afforded active-species mass-transfer coefficients of 3.8μms−1 and 7.5μms−1, respectively, which decreased and became non-Fickian as cycling progressed. At ±10mAcm−2 from 0%–20% state of charge, voltage efficiency with Celgard fell from 96% to 60% over 27 cycles. Separator replacement restored the coulombic and voltage efficiencies, which repeated their first progression. Impedance spectra from series-connected canary cells reveal that separator resistances remain stable during open-circuit exposure to charged single electrolytes, but increase under applied current or open-circuit contact with differently charged electrolytes

A Materials Science Driven Pattern Generation Solution to Fracturing Computer Generated Glass for Films and Games

Believably and realistically fracturing computer generated glass for visual effects has been previously solved through various methods such as algorithmic approaches, utilizing texture maps, or finite element analysis. These solutions can achieve some believable results but often at the cost of one or more of the following: simulation time, preparation time, art directability, consistency with materials science research, or the requirement of creating or utilizing fixed assets or maps. In this thesis I present a novel method that draws from the appropriate literature and focuses on quickly generating accurate fracture patterns. The method takes inputs such as the artist’s animation of an impact and desired object properties, and outputs fracture patterns used for breaking objects apart based on input values, materials science literature, and fracture mechanics. After determining all of the fracture pattern variables such as the number of radial and concentric cracks, the artist is able to override the computed parameters to retain control and art directability. Implementation of this method was performed using MAXScript, the built-in scripting language for Autodesk 3ds Max. The result is a computationally fast and mechanically accurate tool while retaining art directability to fulfill film storyboards or game design

Augmented saddle point formulation of the steady-state Stefan--Maxwell diffusion problem

We investigate structure-preserving finite element discretizations of the steady-state Stefan--Maxwell diffusion problem which governs diffusion within a phase consisting of multiple species. An approach inspired by augmented Lagrangian methods allows us to construct a symmetric positive definite augmented Onsager transport matrix, which in turn leads to an effective numerical algorithm. We prove inf-sup conditions for the continuous and discrete linearized systems and obtain error estimates for a phase consisting of an arbitrary number of species. The discretization preserves the thermodynamically fundamental Gibbs--Duhem equation to machine precision independent of mesh size. The results are illustrated with numerical examples, including an application to modelling the diffusion of oxygen, carbon dioxide, water vapour and nitrogen in the lungs.Comment: 27 pages, 5 figure