Component reliability and weight tradeoff
Component reliability and weight tradeoff analysis for aircraft electrical power system
Source record↗
SEARCH · Engineering Papers
Results for “tradeoff analysis”
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.
Subsystem weight trade-off studies for the design optimization of a planetary landing vehicle
Computerized tradeoff analysis for planetary landing vehicle entry capsule and lander design optimization, emphasizing weight allocation for Mars 1973 missions
Mukhopadhyay, A. K.↗
Progress in aerospace meteorology and review of atmospheric considerations for the space shuttle
Meteorological problems associated with space shuttle design and operations, permitting tradeoff analysis on environment effects
Smith, O. E.↗
Modular Space Station Phase B Extension Preliminary Systems Design Report. Volume VI: Trades and Analyses
This document contains trades and analyses conducted during the Modular Space Station Phase B System Definition. Requirements and concepts considered and the tradeoff analysis leading to the preferred concept are presented. Integrated analyses are presented for subsystems and thermal control. Specific trades and analyses are presented for water management, atmosphere control, energy storage, radiators, navigation, control moment gyros, and system maintenance. The analyses of manipulator concepts and requirements, and supplemental analyses of information management issues are summarized. Subsystem reliability analyses include a detailed discussion of the critical failure analysis.
Jones, A. L.↗
Umbilical Connect Techniques Improvement-Technology Study
The objective of this study was to develop concepts, specifications, designs, techniques, and procedures capable of significantly reducing the time required to connect and verify umbilicals for ground services to the space shuttle. The desired goal was to reduce the current time requirement of several shifts for the Saturn 5/Apollo to an elapsed time of less than one hour to connect and verify all of the space shuttle ground service umbilicals. The study was conducted in four phases: (1) literature and hardware examination, (2) concept development, (3) concept evaluation and tradeoff analysis, and (4) selected concept design. The final product of this study was a detail design of a rise-off disconnect panel prototype test specimen for a LO2/LH2 booster (or an external oxygen/hydrogen tank for an orbiter), a detail design of a swing-arm mounted preflight umbilical carrier prototype test specimen, and a part 1 specification for the umbilical connect and verification design for the vehicles as defined in the space shuttle program.
Valkema, Donald C.↗
Hardware simulation of Ku-band spacecraft receiver and bit synchronizer, volume 1
A hardware simulation which emulates an automatically acquiring transmit receive spread spectrum communication and tracking system and developed for use in future NASA programs involving digital communications is considered. The system architecture and tradeoff analysis that led to the selection of the system to be simulated is presented.
Lindsey, W. C.↗
A tradeoff study of determine the optimum approach to a wash/rinse capability to support future space flight
Specific requirements for a wash/rinse capability to support Spacelab biological experimentation and to identify various concepts for achieving this capability were determined. This included the examination of current state-of-the-art and emerging technology designs that would meet the wash/rinse requirements. Once several concepts were identified, including the disposable utensils, tools and gloves or other possible alternatives, a tradeoff analysis involving system cost, weight, volume utilization, functional performance, maintainability, reliability, power utilization, safety, complexity, etc., was performed so as to determine an optimum approach for achieving a wash/rinse capability to support future space flights. Missions of varying crew size and durations were considered.
Wilson, D. A.↗
Flight representative positive isolation disconnect
Resolutions were developed for each problem encountered and a tradeoff analysis was performed to select a final configuration for a flight representative PID (Positive Isolation Disconnect) that is reduced in size and comparable in weight and pressure drop to the developmental PID. A 6.35 mm (1/4-inch) line size PID was fabricated and tested. The flight representative PID consists of two coupled disconnect halves, each capable of fluid isolation with essentially zero clearance between them for zero leakage upon disconnect half disengagement. An interlocking foolproofing technique prevents uncoupling of disconnect halves prior to fluid isolation. Future development efforts for the Space Shuttle subsystems that would benefit from the use of the positive isolation disconnect are also recommended. Customary units were utilized for principal measurements and calculations with conversion factors being inserted in equations to convert the results to the international system of units.
Rosener, A. A.↗
Ku-band antenna acquisition and tracking performance study, volume 4
The results pertaining to the tradeoff analysis and performance of the Ku-band shuttle antenna pointing and signal acquisition system are presented. The square, hexagonal and spiral antenna trajectories were investigated assuming the TDRS postulated uncertainty region and a flexible statistical model for the location of the TDRS within the uncertainty volume. The scanning trajectories, shuttle/TDRS signal parameters and dynamics, and three signal acquisition algorithms were integrated into a hardware simulation. The hardware simulation is quite flexible in that it allows for the evaluation of signal acquisition performance for an arbitrary (programmable) antenna pattern, a large range of C/N sub O's, various TDRS/shuttle a priori uncertainty distributions, and three distinct signal search algorithms.
Huang, T. C.↗
Orbit Transfer Vehicle (OTV) engine, phase A study. Volume 1: Executive Summary
Design and parametric data for the hydrogen oxygen engine used in the orbiter transfer vehicle are presented. The engine design is analyzed and minimum engine performance and man rating requirements are discussed. Candidate cycle performance, weight and tradeoff analysis, and cost estimates are reported.
Mellish, J. A.↗
A study and experiment plan for digital mobile communication via satellite
The viability of mobile communications is examined within the context of a frequency division multiple access, single channel per carrier satellite system emphasizing digital techniques to serve a large population of users. The intent is to provide the mobile users with a grade of service consistant with the requirements for remote, rural (perhaps emergency) voice communications, but which approaches toll quality speech. A traffic model is derived on which to base the determination of the required maximum number of satellite channels to provide the anticipated level of service. Various voice digitalization and digital modulation schemes are reviewed along with a general link analysis of the mobile system. Demand assignment multiple access considerations and analysis tradeoffs are presented. Finally, a completed configuration is described.
Jones, J. J.↗
Simulation of spaceborne stereo radar imagery - Experimental results
Computer simulation of radar imagery was used to investigate spaceborne stereo radar. The major conclusions reached are that stereo pairs representing different angles of incidence with the same look-direction appear best and that the angles of incidence and stereo intersection angle be matched to the slope and relief of terrain. A parametric tradeoff analysis was performed for eleven different angles of incidence over three different model areas. The eleven angles spanned the range from small- to large-incidence angles. The three model areas were selected as typical of relatively flat, moderately rough, and mountainous terrain. The stereo pair judged best for each model area are included.
Kaupp, V. H.↗
Frequency synthesized and continuously tunable IR laser sources in 9-11 microns
A review of high-resolution microwave-tuned IR laser source with frequency-synthesized outputs exceeding 100 mW is presented. Details are given on system configuration, design parameters, tradeoff analysis, system optimization, and fabrication procedure, along with measured performance characteristics.
Cheo, P. K.↗
Some design characteristics of the AMPTE turn and orbit change maneuvers
The maneuvers carried out by the Active Magnetospheric Particle Tracer Explorers (AMPTE) including the Charge Composition Explorer (CCE) and the Ion Release Module (IRM) spacecraft are analyzed. Analytic and graphical methods are developed in order to carry out sensitivity analyses that helped design the nominal maneuvers, by taking into account errors in burn initiating time, motor performance, and spin axis pointing. A tradeoff analysis between errors in timing and Delta V magnitude is shown for the IRM orbit transfer, and a technique that allows for the determination of the attitude of spinner spacecraft by way of the observed Doppler shift resulting from an unbalanced turn is investigated.
Kechichian, J. A.↗
The conversion of lignocellulosics to fermentable sugars: A survey of current research and application to CELSS
An overview of the options for converting lignocellulosics into fermentable sugars as applied to the Closed Ecological Life Support System (CELSS) is given. A requirement for pretreatment is shown as well as the many available options. At present, physical/chemical methods are the simplest and best characterized options, but enzymatic processes will likely be the method of choice in the future. The use of pentose sugars by microorganisms to produce edibles at levels comparable to conventional plants is shown. The possible use of mycelial food production on pretreated but not hydrolyzed lignocelluloscis is also presented. Simple tradeoff analysis among some of the many possible biological pathways to regeneration of waste lignocellulosics was undertaken. Comparisons with complete oxidation processes were made. It is suggested that the NASA Life Sciences CELSS program maintain relationships with other government agencies involved in lignocellulosic conversions and use their expertise when the actual need for such conversion technology arises rather than develop this expertise within NASA.
Petersen, Gene R.↗
Development of far infrared detection techniques
This grant supports the development of a variety of advanced far infrared detection techniques that will be used in future NASA missions such as the Space Infrared Telescope Facility (SIRTF). These studies span the wavelength region of 30-200 microns and include development of focal planes and electronics that would utilize them. Efforts reported here represent collaborations among the University of Arizona's Steward Observatory; Lawrence Berkeley Laboratories (LBL); and the University of California at Berkeley. The overall goal of this program is to demonstrate extremely high performance detectors for low background applications between 30-200 microns. For the 40-120 micron region, the program is developing a 32x32 filled detector array. Previous work has demonstrated the required performance with a Z-Plane array architecture; we are now upgrading construction facilities and techniques to increase yields and reliability. We have completed the initial tradeoff analysis for the interconnects between the detectors and and readouts. We found satisfactory performance for both Flex-Cable and Tape Automated Bonding (TAB) devices, but analysis showed that an all-sapphire device would not meet our requirements. In addition, the effort continued to develop readouts that can operate close to the detector element temperature; success would substantially improve the manufacturability of the arrays. For the 100-200 micron range, previous work has demonstrated good performance with individual detector elements of stressed Ge:Ga; current efforts are to increase the quantum efficiency of these devices. Work continues to discover how to construct an alternate type of long wave detector, Ge:B Blocked Impurity Band devices. Following descoping of SIRTF, we are closing out the bolometer and refrigerator development. We documented the optical designs and approaches developed previously to meet the specific requirements of these detector types in terms of modulation of the signals for good photometric behavior within the constraints of a compact and self-contained cryogenic instrument. Further study was initiated for the Band 3 optical train, where we have concerns about complexity and the manufacturability of one component.
Rieke, George↗
Model for Simulating a Spiral Software-Development Process
A discrete-event simulation model, and a computer program that implements the model, have been developed as means of analyzing a spiral software-development process. This model can be tailored to specific development environments for use by software project managers in making quantitative cases for deciding among different software-development processes, courses of action, and cost estimates. A spiral process can be contrasted with a waterfall process, which is a traditional process that consists of a sequence of activities that include analysis of requirements, design, coding, testing, and support. A spiral process is an iterative process that can be regarded as a repeating modified waterfall process. Each iteration includes assessment of risk, analysis of requirements, design, coding, testing, delivery, and evaluation. A key difference between a spiral and a waterfall process is that a spiral process can accommodate changes in requirements at each iteration, whereas in a waterfall process, requirements are considered to be fixed from the beginning and, therefore, a waterfall process is not flexible enough for some projects, especially those in which requirements are not known at the beginning or may change during development. For a given project, a spiral process may cost more and take more time than does a waterfall process, but may better satisfy a customer's expectations and needs. Models for simulating various waterfall processes have been developed previously, but until now, there have been no models for simulating spiral processes. The present spiral-process-simulating model and the software that implements it were developed by extending a discrete-event simulation process model of the IEEE 12207 Software Development Process, which was built using commercially available software known as the Process Analysis Tradeoff Tool (PATT). Typical inputs to PATT models include industry-average values of product size (expressed as number of lines of code), productivity (number of lines of code per hour), and number of defects per source line of code. The user provides the number of resources, the overall percent of effort that should be allocated to each process step, and the number of desired staff members for each step. The output of PATT includes the size of the product, a measure of effort, a measure of rework effort, the duration of the entire process, and the numbers of injected, detected, and corrected defects as well as a number of other interesting features. In the development of the present model, steps were added to the IEEE 12207 waterfall process, and this model and its implementing software were made to run repeatedly through the sequence of steps, each repetition representing an iteration in a spiral process. Because the IEEE 12207 model is founded on a waterfall paradigm, it enables direct comparison of spiral and waterfall processes. The model can be used throughout a software-development project to analyze the project as more information becomes available. For instance, data from early iterations can be used as inputs to the model, and the model can be used to estimate the time and cost of carrying the project to completion.
Mizell, Carolyn↗
Shuttle GPS R/PA evaluation analysis and performance tradeoff study
Primary responsibility was understanding and analyzing the various GPS receiver functions as they relate to the shuttle environment. These receiver functions included acquisition properties of the sequential detector, acquisition and tracking properties of the various receiver phase locked loops, and the techniques of sequential receiver operation. In addition to these areas, support was provided in the areas of oscillator stability requirements, antenna management, and navigation filter requirements, including preposition aiding.
Booth, R. W. D.↗