Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “transport problems”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Space Transportation and the Computer Industry: Learning from the Past

Since the space shuttle began flying in 1981, NASA has made a number of attempts to advance the state of the art in space transportation. In spite of billions of dollars invested, and several concerted attempts, no replacement for the shuttle is expected before 2010. Furthermore, the cost of access to space has dropped very slowly over the last two decades. On the other hand, the same two decades have seen dramatic progress in the computer industry. Computational speeds have increased by about a factor of 1000 and available memory, disk space, and network bandwidth has seen similar increases. At the same time, the cost of computing has dropped by about a factor of 10000. Is the space transportation problem simply harder? Or is there something to be learned from the computer industry? In looking for the answers, this paper reviews the early history of NASA's experience with supercomputers and NASA's visionary course change in supercomputer procurement strategy.

Merriam, M. L.↗
NASA NTRS2012

The Transport of Mass, Energy, and Entropy in Cryogenic Support Struts for Engineering Design

Engineers working to understand and reduce cryogenic boil-off must solve a. variety of transport problems. An important class of nonlinear problems involves the thermal and mechanical design of cryogenic struts. These classic problems are scattered about the literature and typically require too many resources to obtain. So, to save time for practicing engineers, the author presents this essay. Herein, a variety of new, old, and revisited analytical and finite difference solutions of the thermal problem are covered in this essay, along with commentary on approach and assumptions, This includes a few thermal radiation and conduction combined mode solution with a discussion on insulation, optimum emissivity, and geometrical phenomenon. Solutions to cooling and heat interception problems are also presented, including a discussion of the entropy generation. And the literature on the combined mechanical and thermal design of cryogenic support struts is reviewed with an introduction to the associated numerical methods.

Elchert, J. P.↗
NASA NTRS2012

The Transport of Mass, Energy, and Entropy in Cryogenic Support Struts for Engineering Design

Engineers working to understand and reduce cryogenic boil-off must solve a variety of transport problems. An important class of nonlinear problems involves the thermal and mechanical design of cryogenic struts. These classic problems are scattered about the literature and typically require too many resources to obtain. So, to save time for practicing engineers, the author presents this essay. Herein, a variety of new, old, and revisited analytical and finite difference solutions of the thermal problem are covered in this essay, along with commentary on approach and assumptions. This includes a few thermal radiation and conduction combined mode solutions with a discussion on insulation, optimum emissivity, and geometrical phenomenon. Solutions to cooling and heat interception problems are also presented, including a discussion of the entropy generation. The literature on the combined mechanical and thermal design of cryogenic support struts is reviewed with an introduction to the associated numerical methods.

Elchert, J. P.↗
NASA NTRS2013

Exploration of Impinging Water Spray Heat Transfer at System Pressures Near the Triple Point

The heat transfer of a water spray impinging upon a surface in a very low pressure environment is of interest to cooling of space vehicles during launch and re-entry, and to industrial processes where flash evaporation occurs. At very low pressure, the process occurs near the triple point of water, and there exists a transient multiphase transport problem of ice, water and water vapor. At the impingement location, there are three heat transfer mechanisms: evaporation, freezing and sublimation. A preliminary heat transfer model was developed to explore the interaction of these mechanisms at the surface and within the spray.

Heat Transfer↗
NASA NTRSDate not supplied

From the Knowledge-based Digital Platform (KbDP) Concept for Advanced Air Mobility Research to a Preliminary Prototype

Advanced Air Mobility (AAM) encompasses a range of innovative operational and technological changes to aviation (electric aircraft, increasingly automated aircraft, increasingly automated airspace operations, etc.) that are transforming aviation’s role in everyday movement of people and goods. There are multiple associated concepts and use cases for AAM, all interrelated, including small Unmanned Aircraft System (UAS) Traffic Management (UTM), Upper-Class E Traffic Management (ETM), Extensible Traffic Management (xTM), Regional Air Mobility (RAM), and Urban Air Mobility (UAM). These AAM operations must integrate with traditional Air Traffic Management (ATM) operations, as well as non-aviation modes of transportation and logistics. National Aeronautics and Space Administration (NASA) is spearheading an innovative digital engineering approach to integrate, communicate, and facilitate the research of multi-modal transportation systems. The Knowledge-based Digital Platform (KbDP) is a concept being developed that ties the workflows of Project Managers (PM), Principal Investigators (PI), and System Engineers together across organizational boundaries. It does so through the management of an information database defined by mathematical, data science, and system engineering principles. Machine Learning (ML) algorithms play a key role in this concept by extracting meaningful knowledge from the information database, which the human user leverages to greatly improve the efficiency and effectiveness of their research. Expected benefits of this concept include improved technology transfers from research to production, improved research portfolio investments, and research outcomes that are more integrated with all aspects of the multi-modal transportation problem. The preliminary KbDP prototype has been realized using UAM as a pathfinder use case and developed by a team of system engineer, software developer, data scientist, and interns.

Systems Engineering↗
NASA NTRSDate not supplied

Sherlock Data Warehouse

Technical Interchange Meeting 2 of 2, with two linked events. Overall Purpose of the Technical Interchange Meeting was to facilitate collaboration on NAS data analytics between FAA and NASA teams, leveraging the great tool developed by NASA, Sherlock Data Warehouse. Conducted the two TIM events, next step is for the leadership to meet and discuss potential future collaborations. Purpose for Technical Interchange Meeting #2 (TIM 2o2); NASA presented data science related use-cases and applications where they have leveraged the NASA Sherlock Data Warehouse to address aviation transportation problems, with priority on aviation safety.

Two TIMs↗
NASA NTRS1975

Survey of projected growth and problems facing air transportation, 1975 - 1985

Results are presented of a survey conducted to determine the current opinion of people working in air transportation demand forecasting on the future of air transportation over the next ten years. In particular, the survey included questions on future demand growth, load factor, fuel prices, introduction date for the next new aircraft, the priorities of problems facing air transportation, and the probability of a substantial change in air transportation regulation. The survey participants included: airlines, manufacturers, universities, government agencies, and other organizations (financial institutions, private research companies, etc.). The results are shown for the average responses within the organization represented as well as the overall averages.

Williams, L. J.↗
NASA NTRS1992

A transportronic solution to the problem of interorbital transportation

An all-electronic transportation system described by the term 'transportronics' is examined as a means of solving the current problem of the high cost of transporting material from low-Earth orbit (LEO) to geostationary orbit (GEO). In this transportation system, low cost electric energy at the surface of the Earth is efficiently converted into microwave power which is then efficiently formed into a narrow beam which is kept incident upon the orbital transfer vehicles (OTV's) by electronic tracking. The incident beam is efficiently captured and converted into DC power by a device which has a very high ratio of DC power output to its mass. Because the mass of the electric thruster is also low, the resulting acceleration is unprecedented for electric-propelled vehicles. However, the performance of the system in terms of transit times from LEO to GEO is penalized by the short time of contact between the beam and the vehicle in low-Earth orbits. This makes it necessary to place the Earth based transmitters and the vehicles in the equatorial plane thus introducing many geopolitical factors. Technically, however, such a system as described in the report may out-perform any other approach to transportation in the LEO to GEO regime. The report describes and analyzes all portions of the beamed microwave power transmission system in considerable detail. An economic analysis of the operating and capital costs is made with the aid of a reference system capable of placing about 130,000 kilograms of payload into GEO each year. More mature states of the system are then examined, to a level in which 60,000 metric tons per year could be placed into GEO.

Brown, William C.↗
NASA NTRS1997

Dynamic Flow Management Problems in Air Transportation

In 1995, over six hundred thousand licensed pilots flew nearly thirty-five million flights into over eighteen thousand U.S. airports, logging more than 519 billion passenger miles. Since demand for air travel has increased by more than 50% in the last decade while capacity has stagnated, congestion is a problem of undeniable practical significance. In this thesis, we will develop optimization techniques that reduce the impact of congestion on the national airspace. We start by determining the optimal release times for flights into the airspace and the optimal speed adjustment while airborne taking into account the capacitated airspace. This is called the Air Traffic Flow Management Problem (TFMP). We address the complexity, showing that it is NP-hard. We build an integer programming formulation that is quite strong as some of the proposed inequalities are facet defining for the convex hull of solutions. For practical problems, the solutions of the LP relaxation of the TFMP are very often integral. In essence, we reduce the problem to efficiently solving large scale linear programming problems. Thus, the computation times are reasonably small for large scale, practical problems involving thousands of flights. Next, we address the problem of determining how to reroute aircraft in the airspace system when faced with dynamically changing weather conditions. This is called the Air Traffic Flow Management Rerouting Problem (TFMRP) We present an integrated mathematical programming approach for the TFMRP, which utilizes several methodologies, in order to minimize delay costs. In order to address the high dimensionality, we present an aggregate model, in which we formulate the TFMRP as a multicommodity, integer, dynamic network flow problem with certain side constraints. Using Lagrangian relaxation, we generate aggregate flows that are decomposed into a collection of flight paths using a randomized rounding heuristic. This collection of paths is used in a packing integer programming formulation, the solution of which generates feasible and near-optimal routes for individual flights. The algorithm, termed the Lagrangian Generation Algorithm, is used to solve practical problems in the southwestern portion of United States in which the solutions are within 1% of the corresponding lower bounds.

Patterson, Sarah Stock↗
NASA NTRS1976

Retrospective studies of operating problems in air transport

An epidemiological model for the study of human errors in aviation is presented. In this approach, retrospective data are used as the basis for formulation of hypotheses as to system factors which may have contributed to such errors. Prospective experimental studies of aviation operations are also required in order to prove or disprove the hypotheses, and to evaluate the effectiveness of intervention techniques designed to solve operational problems in the aviation system.

Billings, C. E.↗
NASA NTRS1976

Transportation options for solar power satellites

Advantages of solar power satellites compared to ground-based solar power installations are related to an almost continuous exposure to sunlight and to a much smaller collector area. An investigation of the transportation cost problem is conducted. Transportation systems based on presently understood technology are considered for the deployment of solar power satellites at potentially competitive costs. It is found that the cost of placement in a geosynchronous orbit is reducible to the range from $500 to $1000/kW. Approaches for achieving dramatic cost reductions are discussed.

Woodcock, G. R.↗
NASA NTRS1989

The new Space Shuttle Transportation System (STS) - Problem, performance, supportability, and programmatic trending program

This paper describes the NASA Space Shuttle Trend Analysis program. The four main areas of the program - problem/reliability, performance, supportability, and programmatic trending - are defined, along with motivation for these areas, the statistical methods used, and illustrative Space Shuttle applications. Also described is the NASA Safety, Reliability, Maintainability and Quality Assurance (SRM&QA) Management Information Center, used to focus management attention on key near-term launch concerns and long-range mission trend issues. Finally, the computer data bases used to support the program and future program enhancements are discussed.

Crawford, J. L.↗