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Many source code tools help software programmers analyze programs as they are being developed, but such tools can no longer be applied once the final programs are shipped to the user. This greatly limits users, security experts, and anyone other than the programmer who wishes to perform additional testing and program analysis. This dissertation is concerned with the development of scalable techniques for statically analyzing binary programs, which can be employed by anyone who has access to the binary. Unfortunately, static binary analysis is often more difficult than static source code analysis because the abstractions that are the basis of source code programs, such as variables, types, functions, and control flow structure, are not explicitly present in binary programs. Previous approaches work around the the lack of abstractions by reasoning about the program at a lower level, but this approach has not scaled as well as equivalent source code techniques that use abstractions. This dissertation investigates an alternative approach to static binary analysis which is called abstraction recovery. The premise of abstraction recovery is that since many binaries are actually compiled from an abstract source language which is more suitable for analysis, the first step of static binary analysis should be to recover such abstractions. Abstraction recovery is shown to be feasible in two real-world applications. First, C abstractions are recovered by a newly developed decompiler. The second application recovers gadget abstractions to automatically generate return-oriented programming (ROP) attacks. Experiments using the decompiler demonstrate that recovering C abstractions improves scalability over low-level analysis, with applications such as verification and detection of buffer overflows seeing an average of 17× improvement. Similarly, gadget abstractions speed up automated ROP attacks by 99×. Though some binary analysis problems do not lend themselves to abstraction recovery because they reason about low-level or syntactic details, abstraction recovery is an attractive alternative to conventional low-level analysis when users are interested in the behavior of the original abstract program from which a binary was compiled, which is often the case.

Lakes near Sudbury, Ontario, experienced widespread acidification and metal-contamination beginning in the late-19th century. These stressors caused extreme damage to regional aquatic systems and their catchments, with aquatic biota experiencing reduced species richness and, in some cases, extirpations. Emission control measures markedly improved pH, however biotic recovery continues to lag water quality improvements, prompting investigation into mechanisms leading to this phenomenon. Due to the lack of long-term monitoring data, I use paleolimnological approaches to examine temporal trends in cladoceran zooplankton, from pre-impact conditions, through the period of acidification/metal contamination, and following the implementation of emission controls. I assess the degree of biotic recovery that has taken place in these lakes, and review the mechanisms that continue to structure cladoceran assemblages. Lakes closest to Sudbury recorded increases of ~15-65% relative abundance of Chydorus brevilabris, concurrent with the late-1800s industrial development. The relative abundance of C. brevilabris remains elevated above pre-impact levels in two Sudbury lakes; however, in Middle Lake, which was neutralized with calcium carbonate, declines in C. brevilabris (to ~pre-impact levels) occurred following neutralization. Conversely, lakes located ~60 km southwest of Sudbury, in Killarney Provincial Park, experienced muted assemblage change, with minor (< ~5%) increases in grazers (e.g., Daphnia spp., Holopedium glacialis) occurring within the past ~40 years. Lakes in Sudbury and Killarney acidified to pH < ~5, however those in Sudbury additionally received high inputs of nickel and copper, which have toxic effects on aquatic organisms, including some Cladocera. Contamination with these metals may have been a primary driver of cladoceran assemblage change. Elevated metal concentrations likely continue to structure the cladoceran assemblages in the Sudbury lakes. In addition, many of the lakes contain altered food webs (e.g., large populations of yellow perch) as a legacy of the acid and metal contamination, acting as a potential barrier to recovery. Finally, warming air temperatures over the past ~40 years, which I link to increases in primary production, may alter the composition of cladoceran species found in these lakes, and therefore prevent a return to pre-impact conditions. / Thesis (Master, Biology) -- Queen's University, 2014-04-28 12:26:39.903

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Baud-rate clock recovery (CR) is gradually gaining popularity in modern serial data transmission systems since these CR techniques do not require edge-samples for extracting timing information. However, previous baud-rate techniques for high-speed serial links either rely on specific 4-bit patterns or uncorrelated random data. This work describes the modeling and design of analog filter front-end aided baud-rate CR schemes. Unlike other baud-rate schemes, this technique is not constrained by the properties of the input random data. Firstly, the thesis develops a hardware-efficient baud-rate algorithm that requires only the slope information of the incoming random data. Called modified sign-sign minimum mean squared error (SSMMSE), this algorithm adjusts the clock sampling phase until the slope is zero through a bang-bang control loop. Secondly, the performance of a modified SSMMSE phase detector is investigated and compared with a conventional edge-sampled phase detector. It is shown that, at severe noise levels, the proposed modified SSMMSE method has better performance compared to the edge-sampled method for equal loop bandwidths.Thirdly, the thesis investigates different hardware-efficient slope detection techniques. Both passive and active filter based slope detection techniques are demonstrated in this work. In addition to slope generation, the active filter performs linear equalization as well. However, the passive filter generates the slope information at higher speeds than the active filter and also consumes less power. The two filters are used to recover a 2-GHz clock by using an external bang-bang loop. In short, the thesis demonstrates that area and power savings can be achieved by utilizing slope information from front-end filters without compromising the performance of the CR unit.

As unmanned aerial vehicles (UAVs) prevail in commercial and first responder applications, the need for safer and more consistent recovery methods is growing. Standard aircraft landing manoeuvres are only possible with a suitable runway which is often unavailable outside of military applications. Alternative recovery approaches can be either contained within the aircraft, ie. parachute or be setup on the ground ie. net landing. By integrating the recovery system into the vehicle, the flight preparation can be streamlined due to the fact that setting up recovering devices is no longer required. The goal of this thesis is to investigate the application of an autonomous vertical landing capability for fixed wing UAVs using articulated motors to enter vertical flight. Using an experimental UAV design, the dynamics of the problem were investigated using recorded flight data. Implementing a decoupled control approach, the aircraft was stabilized to maintain a horizontal hover. Through the characterized plant model that defines the vertical descent behaviour, a control topology was developed and tested in simulation using an optimal control approach. The developed controller was tested on the experimental UAV to verify the vertical landing performance. It was determined that this approach was well suited to autonomous vertical recovery of a fixed wing UAV. In employing this approach to UAV recovery, operators can easily operate in theatres where space for conventional landing does not exist.