A Platform for Automating Chaos Experiments

The Netflix video streaming system is composed of many interacting services. In such a large system, failures in individual services are not uncommon. This paper describes the Chaos Automation Platform, a system for running failure injection experiments on the production system to verify that failures in non-critical services do not result in system outages.Comment: Conference publicatio

The Olympic Glory of Jesse Owens: A Contribution to Civil Rights and Society

Jesse Owens was the star of the Berlin Olympics in 1936. His four gold medals in Hitler\u27s Germany, as an African American, had far reaching implications back in the United States. Despite segregation and a social hierarchy that was an impasse to both black opportunity and achievement, Owens created a lasting legacy that drastically impacted race relations. The purpose of this thesis was to examine what the Olympic glory of Owens represented for society. Owens as an Olympian in 1936 manufactured a brand of social capital that tied people together in commonality—as Americans. As well, in both myth and deed, Owens has been traditionally credited with challenging Hitler\u27s beliefs of Aryan Supremacy. Yet, Owens was also a race pioneer, as his athletic feats were read in newspapers all over the country, and as a result, helped shift the consciousness of Southerners who were historically ignorant of black achievement

Radiative Transfer in the Martian Environment: In-Situ Results from the MSL Curiosity Rover and Laboratory Experimentation on Martian Regolith and Crystalline Rock Analogs

Global circulation models predicted a suppressed planetary boundary layer within Gale Crater prior to the landing of the Mars Science Laboratory. Images from Mars allow the amount of suspended dust near the crater floor to be estimated numerically. The atmosphere within the crater is shown to be relatively dust free compared to the amount of dust inferred in the atmospheric column, suggesting little mixing between the upper and lower layers. The dust within the crater appears to be well mixed horizontally, implying that dust events (such as dust devils or lateral dust transport) in the northern plains of Gale Crater are rare, even during the most convective time of day. This supports the notion of a suppressed planetary boundary layer within Gale Crater. Radiative transfer modeling of the martian atmosphere benefits from this quantification of low-lying dust. This dissertation aims to expand our knowledge of the radiation environment of Mars into its surface and subsurface. The scattering of radiation through analog martian materials is an area with little research. A mini-goniometer is built to collect transmission spectra as a function of scattering angle for martian analog regoliths and crystalline rock samples. Materials show strong forward or isotropic scattering profiles through the samples. The transmission through the materials is assessed at ultraviolet and visible wavelengths. Kieserite and the majority of the rock samples exhibit an isotropic scattering profile and attenuate ultraviolet radiation significantly. Ultraviolet shielding materials are potential ecological niches for biosignatures, and this dissertation aims to guide the search for these environments on present day Mars. Studies into the habitability of martian surface analogs typically assess the amount of radiation transmitting perpendicular into a surface. This does not fully characterize the multiple surface scattering that exists within these materials. The depths at which radioresistant microorganisms can exist on present day Mars are estimated by modeling the isotropic transmission scattering profiles for kieserite and crystalline rocks under martian insolation. A depth between 2 and 10 mm into the martian subsurface is enough to attenuate ultraviolet radiation to levels suitable to terrestrial radioresistant microorganisms

Monochloramine Advanced Oxidation for Removal of Trace Organics in Wastewater

Monochloramine and free chlorine are both common disinfectants and candidates for Advanced Oxidation Processes (AOP). Results from this study show that free chlorine in the form of HOCl and OCl- has faster degradation kinetics for emerging pollutants. Unfortunately, free chlorine only becomes stable after chlorine demand is satisfied. Monochloramine on the other hand, forms instantaneously upon the addition of chlorine in the presence of ammonia and is a relatively stable compound. Advanced Oxidation Processes using UV 254 light with monochloramine has not been thoroughly investigated. In this study, monochloramine AOP is used to degrade p-cresol to illustrate its oxidative effectiveness. Monochloramine AOP is then compared to chlorine AOP; Chlorine AOP can achieve 90% p-cresol degradation after 15 minutes while monochloramine AOP degraded approximately 65% p-cresol after 15 minutes; both results operated at concentrations of 100 µM oxidant, under UV 254 light with an incident irradiance of 10.38 W/m2 , with an initial p-cresol concentration of 10 µM, and using deionized water buffered with 10 mM phosphate buffer at pH 7. The viability of Monochloramine AOP in wastewater is tested in this study; unfortunately, monochloramine AOP only achieves 10% p-cresol reduction in 15 minutes under UV 254 irradiation for wastewater experiments. Lastly, breakpoint curves are generated while under 15 minutes of UV 254 irradiation to directly compare how the molar ratio of Cl2:NH3 affects AOP degradation of p-cresol

Investigation of the role of thermal boundary layer processes in initiating convection under the NASA SPACE Field Program

The current NWS ground based network is not sufficient to capture the dynamic or thermodynamic structure leading to the initiation and organization of air mass moist convective events. Under this investigation we intend to use boundary layer mesoscale models (McNider and Pielke, 1981) to examine the dynamic triggering of convection due to topography and surface thermal contrasts. VAS and MAN's estimates of moisture will be coupled with the dynamic solution to provide an estimate of the total convective potential. Visible GOES images will be used to specify incoming insolation which may lead to surface thermal contrasts and JR skin temperatures will be used to estimate surface moisture (via the surface thermal inertia) (Weizel and Chang, 1988) which can also induce surface thermal contrasts. We will use the SPACE-COHMEX data base to evaluate the ability of the joint mesoscale model satellite products to show skill in predicting the development of air mass convection. We will develop images of model vertical velocity and satellite thermodynamic measures to derive images of predicted convective potential. We will then after suitable geographic registration carry out a pixel by pixel correlation between the model/satellite convective potential and the 'truth' which are the visible images. During the first half of the first year of this investigation we have concentrated on two aspects of the project. The first has been in generating vertical velocity fields from the model for COHMEX case days. We have taken June 19 as the first case and have run the mesoscale model at several different grid resolutions. We are currently developing the composite model/satellite convective image. The second aspect has been the attempted calibration of the surface energy budget to provide the proper horizontal thermal contrasts for convective initiation. We have made extensive progress on this aspect using the FIFE data as a test data set. The calibration technique looks very promising

Determination of Equilibrium Constants for the Reaction between Acetone and HO_2 Using Infrared Kinetic Spectroscopy

The reaction between the hydroperoxy radical, HO_2, and acetone may play an important role in acetone removal and the budget of HO_x radicals in the upper troposphere. We measured the equilibrium constants of this reaction over the temperature range of 215–272 K at an overall pressure of 100 Torr using a flow tube apparatus and laser flash photolysis to produce HO_2. The HO_2 concentration was monitored as a function of time by near-IR diode laser wavelength modulation spectroscopy. The resulting [HO_2] decay curves in the presence of acetone are characterized by an immediate decrease in initial [HO_2] followed by subsequent decay. These curves are interpreted as a rapid (<100 μs) equilibrium reaction between acetone and the HO_2 radical that occurs on time scales faster than the time resolution of the apparatus, followed by subsequent reactions. This separation of time scales between the initial equilibrium and ensuing reactions enabled the determination of the equilibrium constant with values ranging from 4.0 × 10^(–16) to 7.7 × 10^(–1)8 cm^3 molecule^(–1) for T = 215–272 K. Thermodynamic parameters for the reaction determined from a second-law fit of our van’t Hoff plot were Δ_(r)H°_(245) = −35.4 ± 2.0 kJ mol^(–1) and Δ_(r)S°_(245) = −88.2 ± 8.5 J mol^(–1) K^(–1). Recent ab initio calculations predict that the reaction proceeds through a prereactive hydrogen-bonded molecular complex (HO_2–acetone) with subsequent isomerization to a hydroxy–peroxy radical, 2-hydroxyisopropylperoxy (2-HIPP). The calculations differ greatly in the energetics of the complex and the peroxy radical, as well as the transition state for isomerization, leading to significant differences in their predictions of the extent of this reaction at tropospheric temperatures. The current results are consistent with equilibrium formation of the hydrogen-bonded molecular complex on a short time scale (100 μs). Formation of the hydrogen-bonded complex will have a negligible impact on the atmosphere. However, the complex could subsequently isomerize to form the 2-HIPP radical on longer time scales. Further experimental studies are needed to assess the ultimate impact of the reaction of HO_2 and acetone on the atmosphere

EVA Radio DRATS 2011 Report

In the Fall of 2011, National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) participated in the Desert Research and Technology Studies (DRATS) field experiments held near Flagstaff, Arizona. The objective of the DRATS outing is to provide analog mission testing of candidate technologies for space exploration, especially those technologies applicable to human exploration of extra- terrestrial rocky bodies. These activities are performed at locations with similarities to extra-terrestrial conditions. This report describes the Extravehicular Activity (EVA) Dual-Band Radio Communication System which was demonstrated during the 2011 outing. The EVA radio system is designed to transport both voice and telemetry data through a mobile ad hoc wireless network and employs a dual-band radio configuration. Some key characteristics of this system include: 1. Dual-band radio configuration. 2. Intelligent switching between two different capability wireless networks. 3. Self-healing network. 4. Simultaneous data and voice communication