After large loading events, such as earthquakes, buildings are inspected to determine the extent of damage done to the structural systems and whether it is still safe to use. These building inspections are completed mostly by observing visible damage and using engineering judgment to determine the residual strength of structural elements, or members. This approach is subjective, and accurate inspections demand a more robust approach. Non-destructive testing can be performed on structural steel that attempts to quantify a member’s strength, but these tests have marginal accuracy. Permanent instrumentation of a building can also provide data, but sensors must be powered and well maintained. An interdisciplinary team, led by Professors Dawn Lehman and Laura Lowes from the Department of Civil and Environmental Engineering and Professor AJ Boydston from the Department of Chemistry seeks to develop a polymer coating that can provide a better way to quantify strain in building members. The polymer is comprised of strain-sensitive units (mechanophores) that undergo molecular-level transformations as the polymer chains are extended. The chemical reactions provide visible outputs, such as intense changes in color and fluorescence properties. By changing the microstructure of the polymer and mechanophores, we will be able to control the threshold sensitivity and strain-dependent intensity of color changes. Once applied to a member, the polymer would effectively track the strain that the material undergoes through a change in color, which can be correlated to a residual strength. This color can be observed after earthquakes and other extreme events and allow inspectors to quickly and accurately determine structural health. Our research objectives include applying color-changing strain-responsive (mechanochromic) polymer coatings to building members and analyzing the response to applied strain. My contribution to the project is creating the metal samples and testing them after the polymer has been applied.

Over one sixth of the world’s population relies on seasonal snowmelt and glacial runoff for their water resources. With measurable decreases in snow packs and accelerating warming predicted for the next century, quantifying the underlying physical processes describing snow accumulation and melt is critical to making informed water resources decisions. Here we present thermal infrared (TIR) measurements of snow surface temperature collected on the ground and by a small airplane flying over the Tuolumne watershed in Yosemite National Park in February 2016. The plane captured spatial and temporal variations in the temperature of the snow’s surface, while ground measurements provided a reference point to evaluate the aerial measurements’ accuracy. TIR measurements provide a diagnostic tool used to assess model representation of many key processes, including snowmelt rates, sensible and latent heat fluxes, and longwave radiation. Moving forward we plan to incorporate our findings into snow models in order to better represent snow pack dynamics. Initial comparisons between airborne observations and ground based measurements indicate the airborne observations reliably describe snow surface temperature to within two degrees Celsius. This difference indicates a considerable reduction in uncertainty when compared to modeled snow surface temperature.

Use of Computational Fluid Dynamics (CFD), as a design and investigation tool in fields of science and engineering, is rapidly increasing parallel to today’s rapid growth of economically affordable computational hardware and software resources. However, it is extremely important that methodological usages of CFD is established and taught to the current generation of engineers and scientists with an almost same pace compared to current evolution pace of CFD’s usage. Learning a goal-oriented and methodological approach to use CFD would guarantee a reliable, an efficient and economically feasible final engineering designs and products. The core idea of the current project (SFO Project) is to achieve this important task via developing and validating a family of CFD simulations for the most fundamental problems in field of Fluid Mechanics in three CFD packages. The steps of this development and validation process are documented in form of a goal-oriented and methodological approach and made publicly available for use and further development of young scientists and engineers on the web. As a cherry on top, the application of the developed CFD simulations to more complex and real-life problems will be addressed and investigated. The focus of the current presentation is on the CFD simulations development for the flow over a two-dimensional cylinder, as one of the most fundamental and applicable problem in field of Fluid Mechanics. The simulations were first developed for the laminar and steady flow over a cylinder (i.e. Reynolds < 200). The numerical results were compared and validated against previously published experimental and numerical results. These validated simulations are currently being used for simulation and investigation of unsteady laminar flow around a stationary and heated cylinder. In the end the potential application of these developed CFD simulations to the real life, scientific and engineering problems are addressed and investigated.