For organisations like Facebook, high quality software is important. However, the pace of change ... more For organisations like Facebook, high quality software is important. However, the pace of change and increasing complexity of modern code makes it difficult to produce error-free software. Available tools are often lacking in helping programmers develop more reliable and secure applications. Formal verification is a technique able to detect software errors statically, before a product is actually shipped. Although this aspect makes this technology very appealing in principle, in practice there have been many difficulties that have hindered the application of software verification in industrial environments. In particular, in an organisation like Facebook where the release cycle is fast compared to more traditional industries, the deployment of formal techniques is highly challenging. This paper describes our experience in integrating a verification tool based on static analysis into the software development cycle at Facebook.
We report the detection of a transiting super-Earth-sized planet (R= 1.39 ± 0.09R⊕) in a 1.4-day ... more We report the detection of a transiting super-Earth-sized planet (R= 1.39 ± 0.09R⊕) in a 1.4-day orbit around L 168-9 (TOI-134), a bright M1V dwarf (V= 11,K= 7.1) located at 25.15 ± 0.02 pc. The host star was observed in the first sector of the Transiting Exoplanet Survey Satellite (TESS) mission. For confirmation and planet mass measurement purposes, this was followed up with ground-based photometry, seeing-limited and high-resolution imaging, and precise radial velocity (PRV) observations using the HARPS andMagellan/PFS spectrographs. By combining the TESS data and PRV observations, we find the mass of L 168-9 b to be 4.60 ± 0.56M⊕and thus the bulk density to be 1.74−0.33+0.44times higher than that of the Earth. The orbital eccentricity is smaller than 0.21 (95% confidence). This planet is a level one candidate for the TESS mission’s scientific objective of measuring the masses of 50 small planets, and it is one of the most observationally accessible terrestrial planets for future...
Validating models of airspace operations is a particu-lar challenge. These models are often aimed... more Validating models of airspace operations is a particu-lar challenge. These models are often aimed at finding and exploring safety violations, and aim to be accurate representations of real-world behavior. However, the rules governing the behavior are quite complex: non-linear physics, operational modes, human behavior, and stochastic environmental concerns all determine the re-sponses of the system. In order to quantify uncertainty in the model (and by extension, risk in the real world), one recently successful methodology has been to de-velop a response surface replacement for the original model, and to learn the behavior of the system from the response surface. In this paper, we present a study on aircraft runway approaches as modeled in Geor-gia Tech’s Work Models that Compute (WMC) simu-lation. We use a new learner, Genetic-Active Learning for Search-Based Software Engineering (GALE) to dis-cover the Pareto frontiers defined by cognitive struc-tures. These cognitive structures o...
Validating a concept of operation for a complex, safety-critical system (like the National Airspa... more Validating a concept of operation for a complex, safety-critical system (like the National Airspace Sys-tem) is challenging because of the high dimensionality of the controllable parameters and the infinite number of states of the system. In this paper, we use statistical modeling techniques to explore the behavior of a conflict detection and resolution algorithm designed for the terminal airspace. These techniques predict the robustness of the system simulation to both nominal and off-nominal behaviors within the overall airspace. They also can be used to evaluate the output of the simulation against recorded airspace data. Additionally, the techniques carry with them a mathematical value of the worth of each prediction–a statistical uncertainty for any robustness estimate. Uncertainty Quantification (UQ) is the process of quantitative characterization and ultimately a reduction of uncertainties in complex systems. UQ is important for understanding the influence of uncertainties on...
Phantomlike elastomer simulations do not always deform globally affinely in the way that classica... more Phantomlike elastomer simulations do not always deform globally affinely in the way that classical theory predicts. Assuming that each crosslink will deform affinely with its topological neighbors gives much better results, and creates a way to isolate crosslinks with unpredictable deformation properties. The correlation of non-affinities and network properties depends on the constitutive model and boundary condition used. We always find a correlation between local density of crosslinks and degree of non-affinity.
For organisations like Facebook, high quality software is important. However, the pace of change ... more For organisations like Facebook, high quality software is important. However, the pace of change and increasing complexity of modern code makes it difficult to produce error-free software. Available tools are often lacking in helping programmers develop more reliable and secure applications. Formal verification is a technique able to detect software errors statically, before a product is actually shipped. Although this aspect makes this technology very appealing in principle, in practice there have been many difficulties that have hindered the application of software verification in industrial environments. In particular, in an organisation like Facebook where the release cycle is fast compared to more traditional industries, the deployment of formal techniques is highly challenging. This paper describes our experience in integrating a verification tool based on static analysis into the software development cycle at Facebook.
We report the detection of a transiting super-Earth-sized planet (R= 1.39 ± 0.09R⊕) in a 1.4-day ... more We report the detection of a transiting super-Earth-sized planet (R= 1.39 ± 0.09R⊕) in a 1.4-day orbit around L 168-9 (TOI-134), a bright M1V dwarf (V= 11,K= 7.1) located at 25.15 ± 0.02 pc. The host star was observed in the first sector of the Transiting Exoplanet Survey Satellite (TESS) mission. For confirmation and planet mass measurement purposes, this was followed up with ground-based photometry, seeing-limited and high-resolution imaging, and precise radial velocity (PRV) observations using the HARPS andMagellan/PFS spectrographs. By combining the TESS data and PRV observations, we find the mass of L 168-9 b to be 4.60 ± 0.56M⊕and thus the bulk density to be 1.74−0.33+0.44times higher than that of the Earth. The orbital eccentricity is smaller than 0.21 (95% confidence). This planet is a level one candidate for the TESS mission’s scientific objective of measuring the masses of 50 small planets, and it is one of the most observationally accessible terrestrial planets for future...
Validating models of airspace operations is a particu-lar challenge. These models are often aimed... more Validating models of airspace operations is a particu-lar challenge. These models are often aimed at finding and exploring safety violations, and aim to be accurate representations of real-world behavior. However, the rules governing the behavior are quite complex: non-linear physics, operational modes, human behavior, and stochastic environmental concerns all determine the re-sponses of the system. In order to quantify uncertainty in the model (and by extension, risk in the real world), one recently successful methodology has been to de-velop a response surface replacement for the original model, and to learn the behavior of the system from the response surface. In this paper, we present a study on aircraft runway approaches as modeled in Geor-gia Tech’s Work Models that Compute (WMC) simu-lation. We use a new learner, Genetic-Active Learning for Search-Based Software Engineering (GALE) to dis-cover the Pareto frontiers defined by cognitive struc-tures. These cognitive structures o...
Validating a concept of operation for a complex, safety-critical system (like the National Airspa... more Validating a concept of operation for a complex, safety-critical system (like the National Airspace Sys-tem) is challenging because of the high dimensionality of the controllable parameters and the infinite number of states of the system. In this paper, we use statistical modeling techniques to explore the behavior of a conflict detection and resolution algorithm designed for the terminal airspace. These techniques predict the robustness of the system simulation to both nominal and off-nominal behaviors within the overall airspace. They also can be used to evaluate the output of the simulation against recorded airspace data. Additionally, the techniques carry with them a mathematical value of the worth of each prediction–a statistical uncertainty for any robustness estimate. Uncertainty Quantification (UQ) is the process of quantitative characterization and ultimately a reduction of uncertainties in complex systems. UQ is important for understanding the influence of uncertainties on...
Phantomlike elastomer simulations do not always deform globally affinely in the way that classica... more Phantomlike elastomer simulations do not always deform globally affinely in the way that classical theory predicts. Assuming that each crosslink will deform affinely with its topological neighbors gives much better results, and creates a way to isolate crosslinks with unpredictable deformation properties. The correlation of non-affinities and network properties depends on the constitutive model and boundary condition used. We always find a correlation between local density of crosslinks and degree of non-affinity.
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