Sustainable Energy Technologies and Assessments, 2023
The study introduces the benthic microbial fuel cell lander (BMFC Lander)-an newly constructed mo... more The study introduces the benthic microbial fuel cell lander (BMFC Lander)-an newly constructed modification to an untethered instrumented seafloor platform or ''ocean lander" for probing deep-sea energy potential at depths exceeding 1000 meters below the sea surface over long timescales (two to five months). The BMFC Lander's design includes a detachable anode that permits the re-use of its electrical and anode components in subsequent deployments. Six BMFC Landers successfully deployed in the Southern California bight that hosted a variety of water depth and temperature conditions for testing BMFC performance, demonstrating their reliability as platforms for deployment, energy generation and recovery. Four Lander's BMFC payloads generated a combined total energy density of approximately 30 W hrs m-2 from the seafloor. Organic feedstock (chitin) shortened the time to discharge potential and enhanced power production for two BMFCs in deep-sea sediments despite increased depths and lower temperatures. The BMFC Landers, with a low-cost overhead, are adaptable to support a variety of low-power sensors for tracking water parameters.
International Journal of Bifurcation and Chaos, 2016
The nonlinear dynamics of an optoelectronic negative feedback switching circuit is studied. The c... more The nonlinear dynamics of an optoelectronic negative feedback switching circuit is studied. The circuit, composed of a bulb, a photoresistor, a thyristor and a linear resistor, corresponds to a nightlight device whose light is looped back into its light sensor. Periodic bifurcations and deterministic chaos are obtained by the feedback loop created when the thyristor switches on the bulb in the absence of light being detected by the photoresistor and the bulb light is then looped back into the nightlight to switch it off. The experimental signal is analyzed using tools of delay-embedding reconstruction that yield a reconstructed attractor with fractional dimension and positive Lyapunov exponent suggesting chaotic behavior for some parameter values. We construct a simple circuit model reproducing experimental results that qualitatively matches the different dynamical regimes of the experimental apparatus. In particular, we observe an order-chaos-order transition as the strength of the...
Bacteriophages—or phages—are viruses that infect bacteria and are present in large concentrations... more Bacteriophages—or phages—are viruses that infect bacteria and are present in large concentrations in the mucosa that cover the internal organs of animals. Immunoglobulin (Ig) domains on the phage surface interact with mucin molecules, and this has been attributed to an increase in the encounter rates of phage with bacteria in mucus. However, the physical mechanism behind this phenomenon remains unclear. A continuous time random walk (CTRW) model simulating the diffusion due to mucin-T4 phage interactions was developed and calibrated to empirical data. A Langevin stochastic method for Escherichia coli (E. coli) run-and-tumble motility was combined with the phage CTRW model to describe phage-bacteria encounter rates in mucus for different mucus concentrations. Contrary to previous theoretical analyses, the emergent subdiffusion of T4 in mucus did not enhance the encounter rate of T4 against bacteria. Instead, for static E. coli, the diffusive T4 mutant lacking Ig domains outperformed ...
BMFC power output is correlated with costal sediment parameters to predict BMFC performance in th... more BMFC power output is correlated with costal sediment parameters to predict BMFC performance in the natural environment.
Particle transport by means of a vibrating membrane under variable tension
OF THE THESIS PARTICLE TRANSPORT BY MEANS OF A VIBRATING MEMBRANE UNDER VARIABLE TENSION Intended... more OF THE THESIS PARTICLE TRANSPORT BY MEANS OF A VIBRATING MEMBRANE UNDER VARIABLE TENSION Intended for the Department of Mathematics and Statistics by Kevin L. Joiner Master of Science in Applied Mathematics with a Concentrati on in Dynamical Systems San Diego State University, 2013 The complex dynamical properties of particulate granular s ystems are yet to be fully understood by the scientific community. The need for a d eeper understanding of granular systems is made evident by their commonplace statu s in both the natural and industrial environments. The formation of patterns within systems of particles subject to transversely driven vibrations is one focus of research in r ecent years that enhances an understanding of the connection between granular systems a nd their surroundings. The research suggests it is plausible that particulates of a gra nular assembly can be segregated and positioned via waves imposed on a medium’s surface. As a s tudy in the non-contact management of g...
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Papers by Kevin L Joiner