14 CFR 121.519 - Flight time limitations: Deadhead transportation: airplanes.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Flight time limitations: Deadhead transportation: airplanes. 121.519 Section 121.519 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... Limitations: Supplemental Operations § 121.519 Flight time limitations: Deadhead transportation: airplanes...

14 CFR 121.519 - Flight time limitations: Deadhead transportation: airplanes.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Flight time limitations: Deadhead transportation: airplanes. 121.519 Section 121.519 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... Limitations: Supplemental Operations § 121.519 Flight time limitations: Deadhead transportation: airplanes...

14 CFR 121.519 - Flight time limitations: Deadhead transportation: airplanes.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Flight time limitations: Deadhead transportation: airplanes. 121.519 Section 121.519 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... Limitations: Supplemental Operations § 121.519 Flight time limitations: Deadhead transportation: airplanes...

14 CFR 121.519 - Flight time limitations: Deadhead transportation: airplanes.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Flight time limitations: Deadhead transportation: airplanes. 121.519 Section 121.519 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... Limitations: Supplemental Operations § 121.519 Flight time limitations: Deadhead transportation: airplanes...

14 CFR 121.519 - Flight time limitations: Deadhead transportation: airplanes.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Flight time limitations: Deadhead transportation: airplanes. 121.519 Section 121.519 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... Limitations: Supplemental Operations § 121.519 Flight time limitations: Deadhead transportation: airplanes...

"What a Long, Strange Trip It's Been": The Grateful Dead, the Deadheads, and the Refiguration of Subculture."

ERIC Educational Resources Information Center

Lane, Philip J.

The relationship between mass mediated symbol systems and the development of subculture were studied through an analysis of the "hardcore" followers of the rock group, the Grateful Dead, i.e., the "Deadheads." As a way of compiling a "thick description" of the kind proposed by Clifford Geertz (1973), several key areas…

Identifying best practices for snowplow route optimization : final report.

DOT National Transportation Integrated Search

2016-12-01

Well-designed winter maintenance routes result in snow and ice control service that is both more effective, because roads are cleared more rapidly, and more cost-efficient, because deadheading, route overlap and other inefficiencies are reduced or el...

49 CFR 220.311 - Railroad operating employees in deadhead status.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD COMMUNICATIONS Electronic Devices... controlling locomotive may use an electronic device only if the employee is not using the device in such a way... controlling locomotive must have each electronic device turned off with any earpiece removed from the ear— (1...

A Copy of a Book Is Not a Token of a Type

ERIC Educational Resources Information Center

Socher, David

2010-01-01

Masons butter their bricks, gardeners deadhead their roses, and who am I to quibble over terms? However, philosophers routinely speak of "tokens" and "types", as if, so it seems to me, they are bringing a greater measure of precision to the table. Here I shall quibble. I shall try to lead the reader to realize that those philosophers are neither…

Liquid hydrogen turbopump rapid start program. [thermal preconditioning using coatings

NASA Technical Reports Server (NTRS)

Wong, G. S.

1973-01-01

This program was to analyze, test, and evaluate methods of achieving rapid-start of a liquid hydrogen feed system (inlet duct and turbopump) using a minimum of thermal preconditioning time and propellant. The program was divided into four tasks. Task 1 includes analytical studies of the testing conducted in the other three tasks. Task 2 describes the results from laboratory testing of coating samples and the successful adherence of a KX-635 coating to the internal surfaces of the feed system tested in Task 4. Task 3 presents results of testing an uncoated feed system. Tank pressure was varied to determine the effect of flowrate on preconditioning. The discharge volume and the discharge pressure which initiates opening of the discharge valve were varied to determine the effect on deadhead (no through-flow) start transients. Task 4 describes results of testing a similar, internally coated feed system and illustrates the savings in preconditioning time and propellant resulting from the coatings.

Air-Independent Solid Oxide Fuel Cells for NASA's LOX-CH4 Landers

NASA Technical Reports Server (NTRS)

Ryan, Abigail C.; Araghi, Koorosh R.; Farmer, Serene C.

2013-01-01

Gemini, Apollo, and Space Shuttle used fuel cells as main power source for vehicle and water source for life support and thermal PEM (Gemini) and Alkaline (Apollo, Shuttle) fuel cells were used Ideal for short (less than 3 weeks) missions when the required O2 and H2 can be launched with the vehicle. New missions that might require long-duration stays in orbit or at a habitat, cannot rely on the availability of pure reactants but should also aim to be sun-independent - a problem for which Solid Oxide Fuel Cells might be the answer. Recently, NASA has investigated & developed LOX/CH4-propelled landers (Altair, MORPHEUS). In order to preserve mission flexibility, fuel cells are being studied as a potential power source. Much of NASA's fuel cell development has been focused on creating a dead-headed, non-flow through PEM fuel cells which would weigh less and be more reliable than the existing Alkaline and PEM technology; however, LOX/CH4 as a propellant introduces SOFCs as a power option due to their ability to accept those reactants without much reforming.

Urban Domestic Gardens: The Effects of Human Interventions on Garden Composition

NASA Astrophysics Data System (ADS)

Loram, Alison; Warren, Philip; Thompson, Ken; Gaston, Kevin

2011-10-01

Private domestic gardens contribute substantially to the biodiversity of urban areas and benefit human health and well-being. We previously reported a study of 267 gardens across five cities in the United Kingdom in which variation in geographical and climatic factors had little bearing on the richness, diversity and composition of plant species. We therefore hypothesise that garden management is an important factor in determining garden characteristics. Here, from the same sample of gardens, we investigate potential associations between the uses to which people put their gardens, the types of management activities they undertake, and the characteristics of those gardens. Householders ( n = 265) completed a questionnaire detailing various aspects of garden use and management activities. The majority of respondents used their gardens chiefly for relaxation, recreation, and eating. Fewer than one fifth included "gardening" amongst their garden uses even though all performed some garden management, suggesting that not all management activity resulted from an interest in gardening. Garden-watering and lawn-mowing were the most prevalent activities and were predictors of other types of management including weeding, vegetation-cutting, leaf-collection, and dead-heading flowers. A number of these activities were associated with one another, the richness and composition of plant species, and the number of land uses in gardens. However, relationships between management activities and the amount of tall vegetation were less consistent, and garden management appeared to be independent of garden area. More species of amphibians, birds, and mammals were observed in gardens with ponds and in which efforts were made to attract wildlife, particularly by providing drinking water. This study supports the hypothesis that garden use and management is associated with garden characteristics.

Urban domestic gardens: the effects of human interventions on garden composition.

PubMed

Loram, Alison; Warren, Philip; Thompson, Ken; Gaston, Kevin

2011-10-01

Private domestic gardens contribute substantially to the biodiversity of urban areas and benefit human health and well-being. We previously reported a study of 267 gardens across five cities in the United Kingdom in which variation in geographical and climatic factors had little bearing on the richness, diversity and composition of plant species. We therefore hypothesise that garden management is an important factor in determining garden characteristics. Here, from the same sample of gardens, we investigate potential associations between the uses to which people put their gardens, the types of management activities they undertake, and the characteristics of those gardens. Householders (n = 265) completed a questionnaire detailing various aspects of garden use and management activities. The majority of respondents used their gardens chiefly for relaxation, recreation, and eating. Fewer than one fifth included "gardening" amongst their garden uses even though all performed some garden management, suggesting that not all management activity resulted from an interest in gardening. Garden-watering and lawn-mowing were the most prevalent activities and were predictors of other types of management including weeding, vegetation-cutting, leaf-collection, and dead-heading flowers. A number of these activities were associated with one another, the richness and composition of plant species, and the number of land uses in gardens. However, relationships between management activities and the amount of tall vegetation were less consistent, and garden management appeared to be independent of garden area. More species of amphibians, birds, and mammals were observed in gardens with ponds and in which efforts were made to attract wildlife, particularly by providing drinking water. This study supports the hypothesis that garden use and management is associated with garden characteristics.

Ares I Reaction Control System Propellant Feedline Decontamination Modeling

NASA Technical Reports Server (NTRS)

Pasch, James J.

2010-01-01

The objective of the work presented here is to quantify the effects of purge gas temperature, pressure, and mass flow rate on Hydrazine (Hz) decontamination rates of the Ares I Roll Control System and Reaction Control System. A survey of experts in this field revealed the absence of any decontamination rate prediction models. Three basic decontamination methods were identified for analysis and modeling. These include low pressure eduction, high flow rate purge, and pulse purge. For each method, an approach to predict the Hz mass transfer rate, as a function of system pressure, temperature, and purge gas mass flow rate, is developed based on the applicable physics. The models show that low pressure eduction is two orders of magnitude more effective than the high velocity purge, which in turn is two orders of magnitude more effective than the pure diffusion component of pulse purging of deadheads. Eduction subjects the system to low pressure conditions that promote the extraction of Hz vapors. At 120 F, Hz is saturated at approximately 1 psia. At lower pressures and 120 F, Hz will boil, which is an extremely efficient means to remove liquid Hz. The Hz boiling rate is predicted by equating the rate at which energy is added to the saturated liquid Hz through heaters at the tube outer wall with the energy removed from the liquid through evaporation. Boil-off fluxes were predicted by iterating through the range of local pressures with limits set by the minimum allowed pressure of 0.2 psia and maximum allowed wall temperature of 120 F established by the heaters, which gives a saturation pressure of approximately 1.0 psia. Figure 1 shows the resulting boil-off fluxes as a function of local eduction pressure. As depicted in figure 1, the flux is a strong inverse function of eduction pressure, and that minimizing the eduction pressure maximizes the boil-off flux. Also, higher outer wall temperatures lead to higher boil-off fluxes and allow for boil-off over a greater range of eduction pressures.

Towards Energy Efficient and Shared Mobility Services

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rames, Clement L

Throughout the 20th century, automobiles have shaped urban and suburban landscapes, especially in North America. Globally, the car-centric transportation paradigm has contributed to unprecedented issues in terms of air quality, fossil-fuel dependence, carbon emissions lock-in, traffic congestion, road safety, parking scarcity, serious public health concerns, and socioeconomic inequality. Nonetheless, in the United States the percentage of single-occupant vehicle (SOV) commuters has continued to rise since 1960 while the proportion of carpooling has decreased by more than half since 1980. Evolving mobility services, in conjunction with new behavioral insights, have motivated recent inquiries in how to best foster sustainable growth whilemore » reducing traffic congestion and improving health outcomes. Few studies have assessed their true effectiveness, unanticipated effects (e.g., 'dead-head' or 'empty-vehicle' ride-hailing trips) or measured their impact on a specific city (e.g., modal shift, changes in personal miles traveled/vehicle miles traveled). This effort aims to answer the following questions: to what extent can shared mobility help invert the trend of increasing SOV trips? What are the energy risks and benefits of shared mobility? How do interactions between technology, policy, urban design, and behavioral change shape the transition to energy-efficient transportation? To this end, an assessment framework for sustainable urban mobility is developed, incorporating behavioral metrics (percent active transportation, percent transit ridership, percent shared trips), energy use (vehicle miles traveled per capita, percent SOV trips) and urban planning (population density, average commute time). We apply this framework to three cities (Denver, CO; San Francisco, CA; and Paris, France) to evaluate the sustainability of their transportation systems and explore their potential for shared mobility. The influence of incentives, social norms, and public perceptions on the uptake of energy-efficient mobility is further investigated through a review of current policy initiatives and identified best practices. The results from these three cities show strikingly different profiles: SOV trips range from 70% in Denver to 30% in San Francisco and 17% in Paris while transit ridership is 7%, 25%, and 64% of trips, respectively. These figures seem to correlate strongly with population density and degree of mixed-use development, with a ten-fold increase in density from Denver to Paris. Factors such as urban governance structures and level of public transit service further help to explain the observed differences. The framework presented here will help understand the long-term impacts of novel shared mobility solutions to better inform future policy making and investments.« less

DEVELOPMENT OF A LAMINATED DISK FOR THE SPIN TEK ROTARY MICROFILTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herman, D.

2011-06-03

Funded by the Department of Energy Office of Environmental Management, EM-31, the Savannah River National Laboratory (SRNL) partnered with SpinTek Filtration{trademark} to develop a filter disk that would withstand a reverse pressure or flow during operation of the rotary microfilter. The ability to withstand a reverse pressure and flow eliminates a potential accident scenario that could have resulted in damage to the filter membranes. While the original welded filter disks have been shown to withstand and reverse pressure/flow in the static condition, the filter disk design discussed in this report will allow a reverse pressure/flow while the disks are rotating.more » In addition, the laminated disk increases the flexibility during filter startup and cleaning operations. The new filter disk developed by SRNL and SpinTek is manufactured with a more open structure significantly reducing internal flow restrictions in the disk. The prototype was tested at the University of Maryland and demonstrated to withstand the reverse pressure due to the centrifugal action of the rotary filter. The tested water flux of the disk was demonstrated to be 1.34 gpm in a single disk test. By comparison, the water flux of the current disk was 0.49 gpm per disk during a 25 disk test. The disk also demonstrated rejection of solids by filtering a 5 wt % Strontium Carbonate slurry with a filtrate clarity of less the 1.4 Nephelometric Turbidity Units (NTU) throughout the two hour test. The Savannah River National Laboratory (SRNL) has been working with SpinTek Filtration{trademark} to adapt the rotary microfilter for radioactive service in the Department of Energy (DOE) Complex. One potential weakness is the loose nature of the membrane on the filter disks. The current disk is constructed by welding the membrane at the outer edge of the disk. The seal for the center of the membrane is accomplished by an o-ring in compression for the assembled stack. The remainder of the membrane is free floating on the disk. This construction requires that a positive pressure be applied to the rotary filter tank to prevent the membrane from rising from the disk structure and potentially contacting the filter turbulence promoter. In addition, one accident scenario is a reverse flow through the filtrate line due to mis-alignment of valves resulting in the membrane rising from the disk structure. The structural integrity of the current disk has been investigated, and shown that the disk can withstand a significant reverse pressure in a static condition. However, the disk will likely incur damage if the filter stack is rotated during a reverse pressure. The development of a laminated disk would have several significant benefits for the operation of the rotary filter including the prevention of a compromise in filter disk integrity during a reverse flow accident, increasing operational flexibility, and increasing the self cleaning ability of the filter. A laminated disk would allow the filter rotor operation prior to a positive pressure in the filter tank. This would prevent the initial dead-head of the filter and prevent the resulting initial filter cake buildup. The laminated disk would allow rotor operation with cleaning fluid, eliminating the need for a recirculation pump. Additionally, a laminated disk would allow a reverse flow of fluid through the membrane pores removing trapped particles.« less