6,883 research outputs found
Land landing couch dynamics computer program
Computer programs perform landing stability studies of mechanical impact system designs for advanced spacecraft. The programs consider variation in spacecraft vertical and horizontal velocity, attitude and orientation, shock strut load-stroke characteristics, and ground coefficient of friction
Carbon Free Boston: Waste Technical Report
Part of a series of reports that includes:
Carbon Free Boston: Summary Report;
Carbon Free Boston: Social Equity Report;
Carbon Free Boston: Technical Summary;
Carbon Free Boston: Buildings Technical Report;
Carbon Free Boston: Transportation Technical Report;
Carbon Free Boston: Energy Technical Report;
Carbon Free Boston: Offsets Technical Report;
Available at http://sites.bu.edu/cfb/OVERVIEW:
For many people, their most perceptible interaction with their environmental footprint is through the
waste that they generate. On a daily basis people have numerous opportunities to decide whether to
recycle, compost or throwaway. In many cases, such options may not be present or apparent. Even
when such options are available, many lack the knowledge of how to correctly dispose of their waste,
leading to contamination of valuable recycling or compost streams. Once collected, people give little
thought to how their waste is treated. For Boston’s waste, plastic in the disposal stream acts becomes a
fossil fuel used to generate electricity. Organics in the waste stream have the potential to be used to
generate valuable renewable energy, while metals and electronics can be recycled to offset virgin
materials. However, challenges in global recycling markets are burdening municipalities, which are
experiencing higher costs to maintain their recycling.
The disposal of solid waste and wastewater both account for a large and visible anthropogenic impact
on human health and the environment. In terms of climate change, landfilling of solid waste and
wastewater treatment generated emissions of 131.5 Mt CO2e in 2016 or about two percent of total
United States GHG emissions that year. The combustion of solid waste contributed an additional 11.0 Mt
CO2e, over half of which (5.9 Mt CO2e) is attributable to the combustion of plastic [1]. In Massachusetts,
the GHG emissions from landfills (0.4 Mt CO2e), waste combustion (1.2 Mt CO2e), and wastewater (0.5
Mt CO2e) accounted for about 2.7 percent of the state’s gross GHG emissions in 2014 [2].
The City of Boston has begun exploring pathways to Zero Waste, a goal that seeks to systematically
redesign our waste management system that can simultaneously lead to a drastic reduction in emissions
from waste. The easiest way to achieve zero waste is to not generate it in the first place. This can start at
the source with the decision whether or not to consume a product. This is the intent behind banning
disposable items such as plastic bags that have more sustainable substitutes. When consumption occurs,
products must be designed in such a way that their lifecycle impacts and waste footprint are considered.
This includes making durable products, limiting the use of packaging or using organic packaging
materials, taking back goods at the end of their life, and designing products to ensure compatibility with
recycling systems. When reducing waste is unavoidable, efforts to increase recycling and organics
diversion becomes essential for achieving zero waste. [TRUNCATED]Published versio
Dust storms on Mars: Considerations and simulations
Aeolian processes are important in modifying the surface of Mars at present, and appear to have been significant in the geological past. Aeolian activity includes local and global dust storms, the formation of erosional features such as yardangs and depositional features such as sand dunes, and the erosion of rock and soil. As a means of understanding aeolian processes on Mars, an investigation is in progress that includes laboratory simulations, field studies of earth analogs, and interpretation of spacecraft data. This report describes the Martian Surface Wind Tunnel, an experimental facility established at NASA-Ames Research Center, and presents some results of the general investigation. Experiments dealing with wind speeds and other conditions required for the initiation of particle movement on Mars are described and considerations are given to the resulting effectiveness of aeolian erosion
Jupiter: Its infrared spectrum from 10 to 40 microns
Spectral measurements of the thermal radiation from Jupiter in the 16-40 micrometer band were analyzed under the assumption that pressure broadened H2 transitions are responsible for the bulk of the infrared opacity over most of this spectral interval. Both the vertical pressure-temperature profile and the hydrogen mixing ratio were determined. The derived value of the molecular hydrogen mixing ratio, 0.89 + or - 0.11, is consistent with the solar value, 0.86
A remark on non-integral p-adic slopes for modular forms
We give a sufficient condition, namely "Buzzard irregularity", for there to exist a cuspidal eigenform which does not have integral p-adic slope
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