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Viewing 1 to 30 of 1750
2004-07-19
Technical Paper
2004-01-2359
F. Michard, C. Combes, E. Fournier, E. Werling
In the short term, traditional thermal control techniques, currently reaching their potential limit, will no longer meet the challenge imposed by the natural evolution in electronic packaging, characterized by an ever-increasing level of integration and power. In this context, new architectures must be developed, with thermal control based on high performance heat transfer devices. The Integration of Miniature Heat Pipe (MHP) seems to be one of the most effective and promising solutions for the future. This paper summarizes the work, performed within the frame of a partnership with the CNES, aiming at contributing to develop and evaluate this technology. Beyond theoretical and technological studies, we have manufactured or supplied several miniature heat pipe devices (MHPD) to constitute the elementary thermal control blocks, corresponding to the main packaging hierarchical levels (components, boards, equipment) of future generation of space vocation electronic units.
2004-07-19
Technical Paper
2004-01-2262
Christopher A. Looper
There has been an assembly complete maintenance concept of operations associated with International Space Station (ISS) since the earliest design stages. However, ISS has been and will be at an intermediate stage of completion for several more years, requiring an interim solution to conduct maintenance. The ISS Program's logistics and maintenance plan dictates which spare components are on-orbit already and the order in which new ones will launch. This information dictates what Extravehicular Activity (EVA) maintenance capabilities are expected, which then has to be reconciled with the support equipment available that enables EVA to perform those tasks safely and effectively. The interim solution described is characterized by use of those ISS EVA components and methods that have proven efficient and useful during the ISS assembly EVA's performed to date.
2011-04-12
Journal Article
2011-01-0728
Amandeep Singh, Zissimos Mourelatos, Efstratios Nikolaidis
Reliability is an important engineering requirement for consistently delivering acceptable product performance through time. As time progresses, the product may fail due to time-dependent operating conditions and material properties, component degradation, etc. The reliability degradation with time may increase the lifecycle cost due to potential warranty costs, repairs and loss of market share. Reliability is the probability that the system will perform its intended function successfully for a specified time interval. In this work, we consider the first-passage reliability which accounts for the first time failure of non-repairable systems. Methods are available in the literature, which provide an upper bound to the true reliability which may overestimate the true value considerably. Monte-Carlo simulations are accurate but computationally expensive.
2011-04-12
Journal Article
2011-01-0725
Zissimos Mourelatos, Jing Li, Vijitashwa Pandey, Amandeep Singh, Matthew Castanier, David A. Lamb
Understanding reliability is critical in design, maintenance and durability analysis of engineering systems. A reliability simulation methodology is presented in this paper for vehicle fleets using limited data. The method can be used to estimate the reliability of non-repairable as well as repairable systems. It can optimally allocate, based on a target system reliability, individual component reliabilities using a multi-objective optimization algorithm. The algorithm establishes a Pareto front that can be used for optimal tradeoff between reliability and the associated cost. The method uses Monte Carlo simulation to estimate the system failure rate and reliability as a function of time. The probability density functions (PDF) of the time between failures for all components of the system are estimated using either limited data or a user-supplied MTBF (mean time between failures) and its coefficient of variation.
2011-04-12
Journal Article
2011-01-0726
Dan Ghiocel, Dan Negrut, David A. Lamb, David Gorsich
This research paper addresses the ground vehicle reliability prediction process based on a new integrated reliability prediction framework. The integrated stochastic framework combines the computational physics-based predictions with experimental testing information for assessing vehicle reliability. The integrated reliability prediction approach incorporates the following computational steps: i) simulation of stochastic operational environment, ii) vehicle multi-body dynamics analysis, iii) stress prediction in subsystems and components, iv) stochastic progressive damage analysis, and v) component life prediction, including the effects of maintenance and, finally, iv) reliability prediction at component and system level. To solve efficiently and accurately the challenges coming from large-size computational mechanics models and high-dimensional stochastic spaces, a HPC simulation-based approach to the reliability problem was implemented.
1999-10-19
Technical Paper
1999-01-5633
Dimitri N. Mavris, Danielle S. Soban, Matthew C. Largent
In today’s atmosphere of lower U.S. defense spending and reduced research budgets, determining how to allocate resources for research and design has become a critical and challenging task. In the area of aircraft design there are many promising technologies to be explored, yet limited funds with which to explore them. In addition, issues concerning uncertainty in technology readiness as well as the quantification of the impact of a technology (or combinations of technologies), are of key importance during the design process. The methodology presented in this paper details a comprehensive and structured process in which to explore the effects of technology for a given baseline aircraft. This process, called Technology Impact Forecasting (TIF), involves the creation of a forecasting environment for use in conjunction with defined technology scenarios. The advantages and limitations of the method will be discussed, as well its place in an overall methodology used for technology infusion.
1999-08-10
Technical Paper
1999-01-2982
John K. Schmidt, USN, Donald W. Lawson, USN, Brent W. Goodrum, USMC
In order to address a Naval Fleet Logistics Support (VR) Wing Commander’s request to proactively uncover safety factors in VR maintenance operations, a prototype climate survey was taken by VR Wing maintainers in 13 squadrons. Nearly 800 surveys were tabulated, and the results were analyzed using a model for high reliability organizations. Overall, the preliminary analysis of the survey data pointed out some potential areas in the VR Wing and each of its aircraft communities for intervention.
1999-08-10
Technical Paper
1999-01-2980
J.C. Taylor
These results show that FAA certified aircraft mechanics in Asian countries (Japan, Korea, SE Asia, and India) display greater power distance from superiors than do their U.S. counterparts working for the same international air carrier. This finding tends to confirm the findings and theory of Hofestede (1984), as well as recent replications of Hofestede’s work among airline pilots by Helmreich & Merritt (1998). However, divergence from Hofstede’s strong correlation between high power distance and collectivist values is also found in this sample of airline mechanics. The present findings show that mechanics (regardless of national origin) tend to be more uniformly individualistic than Helmreich & Merritt’s international sample of airline pilots, who are in turn considerably more individualistic than Hofstede’s international sample of IBM employees. It is speculated that this divergence is explained by a combination of occupational and organizational factors.
1999-08-10
Technical Paper
1999-01-2979
Manoj S. Patankar
This study, based on Helmreich and Merritt’s (1998) definitions of professional and organizational cultures, identifies the challenges faced by airlines in the United States and India in the implementation of MHF/MRM programs. Data was gathered through ethnographic observations and field interviews (n=350) at two major airlines in the United States and one regional airline in India. The results of this study indicate the following barriers at the professional and organizational levels. At the professional level, an appropriately qualified AMT or AME holds individual airworthiness authority; whereas, the human factors training promotes team performance. Unless specific mechanisms are developed so that the individual AMTs and the AMEs are not coerced into releasing an aircraft in a hurry, the implementation of MHF/MRM programs will not be successful.
1999-10-19
Technical Paper
1999-01-5571
J. Garth Thompson, null, Head, H. Paul Stough, AWIN Project Manager Walter S. Green, Flight Systems Workpackage Leader
A study of the cockpit information system architecture of current single-engine single-pilot aircraft was performed to establish a baseline for the evaluation of the reliability of new cockpit systems being developed through the Advanced General Aviation Transport Experiments (AGATE) program. That study defines a “typical” General Aviation (GA) cockpit information system architecture consisting of 38 components making up 32 subsystems. It also developed a reliability (fault tree) model for the system and utilized a proprietary analysis tool to compute system reliability. Fault tree reliability models have gained wide acceptance since their introduction in the 1960’s to analyze the probability of success of military defense systems. Fault trees use logic gates to express the relationships between failures of the components and resulting failures of subsystems and of the system.
1999-10-19
Technical Paper
1999-01-5508
V. Sundareswaran, R. Behringer, S. Chen, K. Wang
Human Computer Interface (HCI) in applications for the maintenance of complex machinery such as an aircraft can be enhanced by exploiting new developments in HCI. We have developed a multimodal HCI demonstration system for maintenance applications, incorporating Augmented Reality (AR), Speech Recognition, and 3- dimensional audio technologies. The Augmented Reality interface is based on an original dynamic tracking approach to provide rapid update of the scene with graphical overlays. We enhance the use of this interface with speech recognition to control the system and to add annotations using dictation-based text information. A combination of 3-D audio, graphic animations, and text displays is used to communicate information to the user.
1999-10-19
Technical Paper
1999-01-5509
M.S. Vassiliou, V. Sundareswaran, S. Chen, K. Wang
A multipurpose test-bed for integrating user interface and sensor technologies has been developed, based on a client- server architecture. Various interaction modalities (Speech recognition, 3-D Audio, Pointing, wireless Handheld- PC-based control and interaction, sensor interaction, etc.) are implemented as servers, encapsulating and exposing commercial and research software packages. The system allows for integrated user interaction with large and small displays using speech commands combined with pointing, spatialized audio, and other modalities. Simultaneous and independent speech recognition for two users is supported; users may be equipped with conventional acoustic or new body-coupled microphones.
2011-10-18
Technical Paper
2011-01-2804
Philippe Goupil, Andres Marcos
The state-of-practice for aircraft manufacturers to diagnose guidance & control faults and obtain full flight envelope protection at all times is to provide high levels of dissimilar hardware redundancy. This ensures sufficient available control action and allows performing coherency tests, cross and consistency checks, voting mechanisms and built-in test techniques of varying sophistication. This hardware-redundancy based fault detection and diagnosis (FDD) approach is nowadays the standard industrial practice and fits also into current aircraft certification processes while ensuring the highest level of safety standards. In the context of future “sustainable” aircraft (More Affordable, Smarter, Cleaner and Quieter), the Electrical Flight Control System (EFCS) design objectives, originating from structural loads design constraints, are becoming more and more stringent.
1930-01-01
Technical Paper
300032
E. P. Lott, W. L. Smith
CAUSES of troubles and expense to air-transport companies in their airplanes are dealt with comprehensively by the operations manager and a division superintendent of the National Air Transport. Commercial operation is asserted to be the proving ground for the products of both airplane and airplane-engine manufacturers, and four reasons given for this are (a) lack of understanding between the manufacturer and the purchaser as to precisely what is required of the airplane purchased, (b) inability of the manufacturer to deliver a product equal to his anticipation, (c) inability of the operator properly to use and care for the equipment furnished, and (d) the varied and opposed uses to which different operators must put their equipment. Detailed and valuable information is given regarding the parts that give trouble and what should be done to avoid it.
1932-01-01
Technical Paper
320066
John G. Lee
LOW-COST maintenance is secured by attacking the problem before the design is started. The author tells how this important feature can be designed into the airplane. Maintenance requirements should be written into the contract specifications which should indicate the time within which each part should be inspected and serviced. A suggested set of such specifications is submitted. By this procedure maintenance time can be cut in half. The work of designing must not be rushed. To provide for quick maintenance, some broad changes from customary design are needed and will add to first cost but save money in the long run. Numerous recommendations are made as to design or type of important elements which will facilitate maintenance, avoid exasperation and add to passenger safety and comfort.
1958-01-01
Technical Paper
580141
T. R. PIERPOINT, R. S. LESLIE
1958-01-01
Technical Paper
580295
J. F. HILL
1959-01-01
Technical Paper
590081
H. G. SPILLINGER
1959-01-01
Technical Paper
590157
ROBERT E. KIBELE
1957-01-01
Technical Paper
570148
ROMIE A. TAYLOR
1957-01-01
Technical Paper
570153
GEORGE S. SCHAIRER, HERBERT S. CLAYMAN
1955-01-01
Technical Paper
550329
R. J. GARON
1955-01-01
Technical Paper
550327
CHARLES T. MORROW
Separate and combined, or joint effects of environmental conditions are discussed. The importance of the contribution of environmental testing to product reliability is investigated.
1955-01-01
Technical Paper
550324
RAY M. DANIEL
The development of higher performance and reliability in aircraft weapon systems depends to a large extent upon the environmental limits within which this performance and reliability must be obtained. It is the intent of this presentation to show the need for and importance of accurate and realistic environmental design and test criteria, for each weapon system. Further, that existing Military environmental procedures and Specifications are incompatible with requirements for non-piloted weapon systems; not by intent, but by content, and the manner in which they are used by Contractor and Customer alike. A concrete approach to solution of this problem is proposed. One that would define environmental criteria for an individual weapon system by comparing its mission and performance requirements with known global climatic environment, and with the environment created within the system. The Military are asked to provide the means by which that proposed can be accomplished.
1958-01-01
Technical Paper
580073
R.W. MENLEY
1951-01-01
Technical Paper
510134
KEITH BARR McCUTCHEON
The opinions or assertions contained herein are the private ones of the writer and are mot to be construed as official or reflecting the views of the Navy Department or the naval service at large.
1952-01-01
Technical Paper
520235
Donald L. Putt
IN this paper Maj. -Gen. Putt presents the four major limitations today facing the United States Air Force. As mechanical limitations decrease, nature imposes ever new challenges; these natural barriers are paralleled by increased enemy interference, need for the development of new material, more efficient utilization of all resources, and the demand for automatic reliability which will compensate for the inadequacies of the human mind and body in combat flight operations. This factor of human frailty is cited as being responsible for explorations in the new and vast field of space medicine; also for the miniaturization of electronic equipment, leading to weight reduction and the resultant acceleration of development of pilotless aircraft. The writer stresses the dangers inherent in traditionalism, or the turning to the past at the expense of the dynamic future.
Viewing 1 to 30 of 1750

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