Bus reform in Seoul, Republic of Korea

노트 : Case study prepared for Global Report on Human Settlements 201

Preparation and Characterization of Highly Insulating Granular Samples for Electron Yield Measurement

This experiment focuses primarily on the preparation and characterization of granular samples for the eventual purpose of electron yield measurements. Highly insulating granular samples are notoriously difficult to prepare and present a myriad ofcomplications from both experimental and practical frameworks. A famous example of this was during the 1969 Apollo 11 mission when electrostatically adhered lunar dust damaged the equipment and astronauts suits and led to purported health effects. The electrical properties of this dust for charging and discharge is essential to preventing these effects. In this study, particles of varying size, shape, and composition are used to create multilayered samples with a wide range of particulate coverage on a substrate that can withstand vacuum conditions. The particulate samples were characterized and subsequent electron emission measurements were then compared to measurements of the bulk particulate and substrate materials. Measurements demonstrated the ability to perform these difficult measurements and how the sample properties affected yields

Solar Electron Radiation Effects on NASA Space Station Samples

The Lunar Gateway Space Station is meant to aid in the re-exploration of the moon and must be able to survive the harsh conditions in space, specifically solar electron radiation. The experiment investigated potential materials for the Gateway mission and how they withstand high energy electron bombardment meant to mimic a portion of this solar radiation. Potential material damage that can impact spacecraft performance includes charging, arc-induced blow off, and changes in color and other optical properties. The samples were exposed to a beam of high energy electrons (30 keV) for several minutes, while current and video data was recorded. The location, magnitude and timing of charging and discharge was also monitored during beam exposure using visible videos to detect cathodoluminescence and arc discharges. High resolution photos of the samples taken before and after beam exposure are used to investigate electron-beam induced changes. The resulting data indicates locations of possible damage done through certain mechanisms such as electrostatic breakdown (ESD), which can occur when voltage variance within the material exceeds the dielectric strength, creating destructive current paths within the material. The highly insulating materials tested included a complex fiberglass weave (Betacloth) and perfluoroalkoxy alkane (PFA). PFA showed the most signs of damage, especially optical discoloration. Any other small scale signs of physical damage are still being investigated. The results of this experiment will then be submitted to NASA for consideration in regards to the Gateway project. Presentation Time: Wednesday, 1-2 p.m

Preparation, Characterization and Electron Yield Analysis on Highly Insulating Granular Particles

This study focuses on obtaining reliable electron yield measurements of highly insulating granular particles of various shape, size, and composition. Measurements of this kind have long been considered too difficult to collect on granular samples due to experimental complexities leading to a critical knowledge gap in the fundamental electrostatic behaviors of dust. A significant portion of this study was spent on preparing and characterizing granular samples before any type of measurement took place. Particles of varying sizes ranging from ~1 μm to ~100 μm, shapes including cubical, spherical, and angular, and composition including NaCl, MgO, Al2O3 and LHS1, were used to create a multilayered sample with a wide range of particulate coverage on an adhesive substrate that can withstand vacuum conditions. After preparation these particulate samples were characterized via scanning electron microscopy and subsequent electron emission measurements were then compared to measurements of the bulk particulate and substrate materials. Results demonstrated the ability to perform these difficult measurements and how the varying sample properties like roughness and coverage affected yields

USING SATELLITE IMAGERY IN PREDICTING KANSAS FARMLAND VALUES

Can remotely sensed imagery improve hedonic land price models? A remotely sensed variable was added to a hedonic farmland value model as a proxy for land productivity. Land cover data were used to obtain urban and recreational effects as well. The urban and recreational effects were statistically significant but economically small. The remotely sensed productivity variable was statistically significant and economically large, indicating that knowing the "greenness" of the land increased the explanatory power of the hedonic price model. Thus, depending upon the cost of this information, including remotely sensed imagery in traditional hedonic land price models is economically beneficial.Land Economics/Use,

Contamination of Detained Sediment in Sustainable Urban Drainage Systems

Adsorption is a key water pollution remediation measure used to achieve stormwater quality improvement in Sustainable urban Drainage Systems (SuDS). The level of contamination of detained sediment within SuDS assets is not well documented, with published investigations limited to specific contaminant occurrence in ponds, wetlands or infiltration devices (bioretention cells) and generally focused on solute or suspended sediment. Guidance on contamination threshold levels and potential deposited sediment contamination information is not included in current UK SuDS design or maintenance guidance, primarily due to a lack of evidence and understanding. There is a need to understand possible deposited sediment contamination levels in SuDS, specifically in relation to sediment removal maintenance activities and potential impact on receiving waterways of conveyed sediment. Thus, the objective of the research presented herein was to identify what major elements and trace metals were observable in (the investigated) SuDS assets detained sediment, the concentration of these major elements and trace metals and whether they met/surpassed ecotoxicity or contaminated land thresholds. The research presented here provides evidence of investigated SuDS sediment major element and trace metal levels to help inform guidance and maintenance needs, and presents a new methodology to identify the general cause (anthropocentric land use) and extent of detained SuDS fine urban sediment contamination through use of a contamination matrix

The short-term influence of cumulative, sequential rainfall-runoff flows on sediment retention and transport in selected SuDS devices

It is necessary to understand Sustainable urban Drainage Systems (SuDS) sediment retention efficiencies to fully comprehend SuDS pollution removal properties and urban sediment movement from source-to sink. This research presents the detention and transport of a single tagged sediment release through four SuDS devices over 12 months, with the aim of quasi-quantifying these selected SuDS devices sediment detention efficiencies. Field monitoring and mass balance analysis of deposited sediment shows that tagged sediment from the single sediment release moves through the monitored SuDS, with deposition declining over the 12-month monitoring period. Initial retention is high (>80% during the first week of monitoring) but falls below 80% after multiple consecutive rainfall-runoff events (events ≤50% ARI). The field monitoring illustrates retention to generally remain above 50%, suggesting that SuDS are highly efficient at retaining urban sediment pollution but that deposition of a single sediment release may resuspend due to cumulative rainfall-runoff events