Water scarcity is a serious global issue, due to the increasing population and developing economy, and membrane technology is an essential way to address this problem. Forward osmosis (FO) is an emerging membrane process, due to its low energy consumption (not considering the draw solute regeneration). A bottleneck to advance this technology is the design of the support layer for FO membranes to minimize the internal concentration polarization. In this dissertation, we focus on the structural study and modification of the support layer for FO membranes. Firstly, we digitally reconstruct different membrane morphologies in 3D and propose a method for predicting performance in ultrafiltration operations. Membranes with analogous morphologies are later used as substrate for FO membranes. Secondly, we experimentally apply substrates with different potentially suitable morphologies as an FO support layer. We investigate their FO performance after generating a selective polyamide layer on the top, by interfacial polymerization. Among the different substrates we include standard asymmetric porous membranes prepared from homopolymers, such as polysulfone. Additionally block copolymer membrane and Anodisc alumina membrane are chosen based on their exceptional structures, with cylindrical pores at least in part. 3D digitally reconstructed porous substrates, analogous to those investigated for ultrafiltration, are then used to model the performance in FO operation. Finally, we analyze the effect of intermediate layers between the porous substrate and the interfacial polymerized layer. We investigate two materials including chitosan and hydrogel. The main results are the following. Pore-scale modeling for digital membrane generation effectively predicts the velocity profile in different layers of the membrane and the performance in UF experiments. Flow simulations confirm the advantage of finger-like substrates over sponge-like ones, when high water permeance is sought. Cylindrical pores are advantageous for mass transfer. Block copolymer substrates have cylindrical pores in the top layer and very regular pore pattern at the surface. The Anodisc alumina membrane has cylindrical pores from top to bottom. Both substrates were experimentally tested for FO application successfully. A Darcy permeability higher than 1E-20 m2 for the intermediate layer would be necessary in order to facilitate the water flow.

The typical architecture of the proton exchange membrane fuel cell (PEMFC) contains a layer called the microporous sublayer (MSL). The MSL is a mixture of carbon black and polytetrafluoroethylene (PTFE), which is typically applied to the gas diffusion layer (GDL). The composition (wt.% PTFE) and loading (mg/cm2) can be varied to optimize the electrochemical performance of the PEMFC and the overall adhesion of the layers within the PEMFC. This research establishes correlations that characterize the performance and adhesion of the layers within the PEMFC based on composition, loading, fabrication pressure, and fabrication time. MSL loading was varied from 1.5-4 mg/cm2, composition was varied from 10-50 wt.% PTFE, fabrication pressure was varied from 3.45-10.34 MPa, and fabrication time was varied from 2-8 minutes. Using these four factors, correlations were created, and optimal solutions for each response were identified. The adhesion correlation identifies a low MSL loading, mid-range MSL composition, high fabrication pressure, and high fabrication time as desirable factors. The performance correlation suggests that the PEMFC performance is enhanced with low MSL loadings, low MSL PTFE content, and a low fabrication pressure and does not find fabrication time to be a significant factor in the correlation. / Master of Science

<p>System emulation and firmware re-hosting are popular techniques to answer various security and performance related questions, such as, does a firmware contain security vulnerabilities or meet timing requirements when run on a specific hardware platform. While this motivation for emulation and binary analysis has previously been explored and reported, starting to work or research in the field is difficult. Further, doing the actual firmware re-hosting for various Instruction Set Architectures(ISA) is usually time consuming and difficult, and at times may seem impossible. To this end, I provide a comprehensive guide for the practitioner or system emulation researcher, along with various tools that work for a large number of ISAs, reducing the challenges of getting re-hosting working or porting previous work for new architectures. I layout the common challenges faced during firmware re-hosting and explain successive steps and survey common tools to overcome these challenges. I provide emulation classification techniques on five different axes, including emulator methods, system type, fidelity, emulator purpose, and control. These classifications and comparison criteria enable the practitioner to determine the appropriate tool for emulation. I use these classifications to categorize popular works in the field and present 28 common challenges faced when creating, emulating and analyzing a system, from obtaining firmware to post emulation analysis. I then introduce a HALucinator [1 ]/QEMU [2 ] tracer tool named HQTracer, a binary function matching tool PMatch, and GHALdra, an emulator that works for more than 30 different ISAs and enables High Level Emulation.</p>