CHASING THE UNKNOWN: A PREDICTIVE MODEL TO DEMYSTIFY BGP COMMUNITY SEMANTICS

The Border Gateway Protocol (BGP) specifies an optional communities attribute for traffic engineering, route manipulation, remotely-triggered blackholing, and other services. However, communities have neither unifying semantics nor cryptographic protections and often propagate much farther than intended. Consequently, Autonomous System (AS) operators are free to define their own community values. This research is a proof-of-concept for a machine learning approach to prediction of community semantics; it attempts a quantitative measurement of semantic predictability between different AS semantic schemata. Ground-truth community semantics data were collated and manually labeled according to a unified taxonomy of community services. Various classification algorithms, including a feed-forward Multi-Layer Perceptron and a Random Forest, were used as the estimator for a One-vs-All multi-class model and trained according to a feature set engineered from this data. The best model's performance on the test set indicates as much as 89.15% of these semantics can be accurately predicted according to a proposed standard taxonomy of community services. This model was additionally applied to historical BGP data from various route collectors to estimate the taxonomic distribution of communities transiting the control plane.http://archive.org/details/chasingtheunknow1094566047Outstanding ThesisCivilian, CyberCorps - Scholarship For ServiceApproved for public release. distribution is unlimite

Doctor of Philosophy

dissertationIndustrial electrowinning systems are by nature complex, and it can be challenging to evaluate the effects of parametric variation experimentally in production environments. Finite element simulations provide an alternative to physical experimentation. However, simulation of these systems are resource intensive and require coupled multiphysics interactions to accurately model. Despite these challenges, simulation can provide a cost effective means for improvement and optimization. To make it easier to improve operational efficiency and reducing electrowinning costs a model was developed using COMSOL Multiphysics finite element analysis (FEA) software. This work reviews the literature published on the subject providing context to the potential advances in approach. The proposed modeling strategy is presented, beginning with the Nernst--Planck equation describing the migration, convection and diffusion of ionic constituents in an electrolyte. This was coupled with a two-phase computational fluid dynamics (CFD) model to accurately describe mass transport in the system. This coupled approach will allow for accurate deposit morphology modeling. Further, roughness, operational cost and various stochastic methods will be incorporated to describe shorting and cost impact. The objective of this work is to provide a validated, more advanced model to determine the effects of operational parameters on electrowinning performance to facilitate optimization

Assessment of the Impact of Various Ionospheric Models on High Frequency Signal Raytracing

An assessment of the impact of various ionospheric models on high-frequency (HF) signal raytracing is presented. Ionospheric refraction can strongly affect the propagation of HF signals. Consequently, Department of Defense missions such as over-the-horizon RADAR, HF communications, and geo-location all depend on an accurate specification of the ionosphere. Five case studies explore ionospheric conditions ranging from quiet conditions to solar flares and geomagnetic storms. It is shown that an E layer by itself can increase an HF signal’s ground range by over 100 km, stressing the importance of accurately specifying the lower ionosphere. It is also shown that the GPSII model has the potential to capture the expected daily variability of the ionosphere by using Total Electron Content data. This daily variability can change an HF signal’s ground range by as much as 5 km per day. The upper-ionospheric response to both a solar flare and a geomagnetic storm is captured by the GPSII model. In contrast, the GPSII model does not capture the lower-ionospheric response to either event. These results suggest that using the GPSII model’s passive technique by itself may only be beneficial to specifying the ionosphere above the E region, especially during solar flares and geomagnetic storms

Hard-disk equation of state: First-order liquid-hexatic transition in two dimensions with three simulation methods

We report large-scale computer simulations of the hard-disk system at high densities in the region of the melting transition. Our simulations reproduce the equation of state, previously obtained using the event-chain Monte Carlo algorithm, with a massively parallel implementation of the local Monte Carlo method and with event-driven molecular dynamics. We analyze the relative performance of these simulation methods to sample configuration space and approach equilibrium. Our results confirm the first-order nature of the melting phase transition in hard disks. Phase coexistence is visualized for individual configurations via the orientational order parameter field. The analysis of positional order confirms the existence of the hexatic phase.Comment: 9 pages, 8 figures, 2 table

Machining Fixture Design for Multi-Feature Weldment

Current fixture for machining an OEM weldment is lacking robustness and ease of use. An improved machining fixture for use in a horizontal machining center is desired

Inner-Insulated Turbocharger Technology to Reduce Emissions and Fuel Consumption from Modern Engines

Reducing emissions from light duty vehicles is critical to meet current and future air quality targets. With more focus on real world emissions from light-duty vehicles, the interactions between engine and exhaust gas aftertreatment are critical. For modern engines, most emissions are generated during the warm-up phase following a cold start. For Diesel engines this is exaggerated due to colder exhaust temperatures and larger aftertreatment systems. The De-NOx aftertreatment can be particularly problematic. Engine manufacturers are required to take measures to address these temperature issues which often result in higher fuel consumption (retarding combustion, increasing engine load or reducing the Diesel air-fuel ratio). In this paper we consider an inner-insulated turbocharger as an alternative, passive technology which aims to reduce the exhaust heat losses between the engine and the aftertreatment. Firstly, the concept and design of the inner-insulated turbocharger is presented. A transient 3D CFD/FEM (Computation Fluid Dynamics/Finite Element Modelling) simulation is conducted and predicts that external heat losses will be reduced by 70% compared to a standard turbocharger, i.e. non-insulated turbocharger. A 1D modelling methodology is then presented for capturing the behaviour of the inner-insulated turbocharger. This is important as conventional models based on isentropic efficiency maps cannot accurately predict turbine outlet temperature. The alternative model is essential to demonstrate benefits in system-level simulations. Experimental results are presented from a transient air-path testing facility to validate the 1D model and demonstrate the characteristics of the inner-insulated turbocharger. Finally, the validated 1D model is used within a powertrain optimization simulation to demonstrate an improvement in fuel consumption for iso-NOx emissions over a low load city cycle of up to 3%. The work was conducted under the THOMSON project which has received funding from the European Union's Horizon 2020 Program for research, technological development and demonstration under Agreement no. 724037. The project aims to increase the market penetration of 48V hybrid vehicles.</p

Application of Eh-pH Diagrams on Acid Leaching Systems for the Recovery of REEs from Bastnaesite, Monazite and Xenotime

Bastnaesite, monazite and xenotime are rare earth minerals (REMs) that are typical sources for rare earth elements (REEs). To advance the understanding of their leaching and precipitation behavior in different hydrometallurgical processes, Eh-pH diagrams were constructed and modified using the HSC 9.9 software. The aqueous stability of rare earth elements in H2O and acid leaching systems, i.e., the REE-Ligands-H2O systems, were depicted and studied based on the Eh-pH diagrams. This study considers the most relevant lixiviants, their resulting equilibrium states and the importance in the hydrometallurgical recovery of rare earth elements (REMs). A literature review was performed summarizing relevant Eh-pH diagrams and associated thermodynamic data. Shifting stability regions for REEs were discovered with additions of acid ligands and a narrow stability region for soluble REE-(SO4/Cl/NO3) complexes under highly acidic conditions. As such, the recovery of REEs can be enhanced by adjusting pH and Eh values. In addition, the Eh-pH diagrams of the major contaminants (i.e., Fe, Ca and Al) in leaching systems were studied. The resulting Eh-pH diagrams provide possible insights into potential passivation on the particle surfaces due to the formation of an insoluble product layer

Inner-Insulated Turbocharger Technology to Reduce Emissions and Fuel Consumption from Modern Engines

Reducing emissions from light duty vehicles is critical to meet current and future air quality targets. With more focus on real world emissions from light-duty vehicles, the interactions between engine and exhaust gas aftertreatment are critical. For modern engines, most emissions are generated during the warm-up phase following a cold start. For Diesel engines this is exaggerated due to colder exhaust temperatures and larger aftertreatment systems. The De-NOx aftertreatment can be particularly problematic. Engine manufacturers are required to take measures to address these temperature issues which often result in higher fuel consumption (retarding combustion, increasing engine load or reducing the Diesel air-fuel ratio). In this paper we consider an inner-insulated turbocharger as an alternative, passive technology which aims to reduce the exhaust heat losses between the engine and the aftertreatment. Firstly, the concept and design of the inner-insulated turbocharger is presented. A transient 3D CFD/FEM (Computation Fluid Dynamics/Finite Element Modelling) simulation is conducted and predicts that external heat losses will be reduced by 70% compared to a standard turbocharger, i.e. non-insulated turbocharger. A 1D modelling methodology is then presented for capturing the behaviour of the inner-insulated turbocharger. This is important as conventional models based on isentropic efficiency maps cannot accurately predict turbine outlet temperature. The alternative model is essential to demonstrate benefits in system-level simulations. Experimental results are presented from a transient air-path testing facility to validate the 1D model and demonstrate the characteristics of the inner-insulated turbocharger. Finally, the validated 1D model is used within a powertrain optimization simulation to demonstrate an improvement in fuel consumption for iso-NOx emissions over a low load city cycle of up to 3%. The work was conducted under the THOMSON project which has received funding from the European Union's Horizon 2020 Program for research, technological development and demonstration under Agreement no. 724037. The project aims to increase the market penetration of 48V hybrid vehicles.</p

Application strategy for an anthraquinonebased repellent and the protection of soybeans from Canada goose depredation

Agricultural crops can sustain extensive damage caused by Canada geese (Branta canadensis) when these crops are planted near wetlands or brood-rearing sites. From 2000 to 2015, South Dakota Game, Fish and Parks spent \u3e$5.6 million to manage damages caused by Canada geese to agricultural crops (primarily soybeans) in South Dakota, USA. For the purpose of developing a repellent application strategy for nonlethal goose damage management, we comparatively evaluated the width of anthraquinone applications (i.e., 9.4 L Flight Control® Plus goose repellent/ha [active ingredient: 50% 9,10-anthraquinone] at 0–36 m versus 0–73 m perpendicular to the edge of wetlands in 2014), the timing of the first repellent application (i.e., 9.4 L Flight Control Plus goose repellent/ha at 50% versus 75% seedling emergence in 2015), the yield of soybeans (Glycine max) within repellent-treated and untreated subplots, and anthraquinone chemical residues in Day County, South Dakota. Soybean yield was greater in subplots 73 m from the water’s edge than that in the 36-m subplots (P \u3c 0.02). Among subplots first sprayed at 50% seedling emergence, soybean yield was greater at 73 m and 82 m than that at 36 m (P \u3c 0.005). In contrast, we observed no difference in yield at 36 m, 73 m, or 82 m in the subplots first sprayed at 72% seedling emergence (P \u3e 0.09). We therefore conclude that goose damages were effectively managed in subplots first sprayed at 72% seedling emergence. Anthraquinone residues averaged 674 and 629 ppm anthraquinone upon the first application of the repellent (June to July), 22 and 35 ppm anthraquinone in the mid-season hay (August to September), and 36 and 28 ppb anthraquinone in the harvested seed (October to November) in 2014 and 2015, respectively. Our results suggest that a 73-m bandwidth of anthraquinone-based repellents first applied at approximately 72% or 65–85% seedling emergence can protect soybeans from Canada goose depredation

Application Strategy for an Anthraquinone-Based Repellent and the Protection of Soybeans from Canada Goose Depredation

Agricultural crops can sustain extensive damage caused by Canada geese (Branta canadensis) when these crops are planted near wetlands or brood-rearing sites. From 2000 to 2015, South Dakota Game, Fish and Parks spent \u3e$5.6 million to manage damages caused by Canada geese to agricultural crops (primarily soybeans) in South Dakota, USA. For the purpose of developing a repellent application strategy for nonlethal goose damage management, we comparatively evaluated the width of anthraquinone applications (i.e., 9.4 L Flight Control® Plus goose repellent/ha [active ingredient: 50% 9,10-anthraquinone] at 0–36 m versus 0–73 m perpendicular to the edge of wetlands in 2014), the timing of the first repellent application (i.e., 9.4 L Flight Control Plus goose repellent/ha at 50% versus 75% seedling emergence in 2015), the yield of soybeans (Glycine max) within repellent-treated and untreated subplots, and anthraquinone chemical residues in Day County, South Dakota. Soybean yield was greater in subplots 73 m from the water’s edge than that in the 36-m subplots (P \u3c 0.02). Among subplots first sprayed at 50% seedling emergence, soybean yield was greater at 73 m and 82 m than that at 36 m (P \u3c 0.005). In contrast, we observed no difference in yield at 36 m, 73 m, or 82 m in the subplots first sprayed at 72% seedling emergence (P \u3e 0.09). We therefore conclude that goose damages were effectively managed in subplots first sprayed at 72% seedling emergence. Anthraquinone residues averaged 674 and 629 ppm anthraquinone upon the first application of the repellent (June to July), 22 and 35 ppm anthraquinone in the mid-season hay (August to September), and 36 and 28 ppb anthraquinone in the harvested seed (October to November) in 2014 and 2015, respectively. Our results suggest that a 73-m bandwidth of anthraquinone-based repellents first applied at approximately 72% or 65–85% seedling emergence can protect soybeans from Canada goose depredation