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Viewing 1 to 30 of 722
2011-04-12
Technical Paper
2011-01-0161
Tsuneaki Ishima, Yasushi Takahashi, Haruki Okado, Yasukazu Baba, Tomio Obokata
In CFD (Computational Fluid Dynamics) verification of vehicle aerodynamics, detailed velocity measurements are required. The conventional 2D-PIV (Two Dimensional Particle Image Velocimetry) needs at least twice the number of operations to measure the three components of velocity ( u,v,w ), thus it is difficult to set up precise measurement positions. Furthermore, there are some areas where measurements are rendered impossible due to the relative position of the object and the optical system. That is why the acquisition of detailed velocity data around a vehicle has not yet been attained. In this study, a detailed velocity measurement was conducted using a 3D-PIV measurement system. The measurement target was a quarter scale SAE standard vehicle model. The wind tunnel system which was also designed for a quarter scale car model was utilized. It consisted of a moving belt and a boundary suction system.
2013-04-08
Journal Article
2013-01-1230
Steffen Ostendorff, Joerg Sachsse, Heinz-Dietrich Wuttke, Jorge Meza Escobar
This paper presents an adaptive test approach to improve the structural testing of printed circuit boards (PCB) found in electronic automotive components. The approach makes use of FPGAs available on the PCBs, and its applicability is supported by the global trend taking place in the automotive industry of replacing ASICs with programmable devices such as FPGAs. For structural testing of PCBs, Boundary Scan (BScan) is mostly used. However, BScan has the disadvantage of being a static test method due to the slow execution speed reducing the fault coverage concerning dynamic faults. FPGAs support BScan as well, but they also offer a vast number of programmable resources. These resources can be configured for testing purposes. Our approach is to speed-up the testing process during the PCB manufacturing by moving data intensive processing from the external software side (Test-PC) to the programmable hardware side on-board (FPGA), reducing the data transfer over the slow JTAG interface.
2013-04-08
Journal Article
2013-01-1228
Graciela Becci, Gunwant Dhadyalla, Alexandros Mouzakitis, James Marco, Andrew David Moore
Testing real-time vehicular systems challenges the tester to design test cases for concurrent and sequential input events, emulating unexpected user and usage profiles. The vehicle response should be robust to unexpected user actions. Sequence Covering Arrays (SCA) offer an approach which can emulate such unexpected user actions by generating an optimized set of test vectors which cover all possible t-way sequences of events. The objective of this research was to find an efficient nonfunctional sequence testing (NFST) strategy for testing the robustness of real-time automotive embedded systems measured by their ability to recover (prove-out test) after applying sequences of user and usage patterns generated by combinatorial test algorithms, considered as “noisy” inputs. The method was validated with a case study of an automotive embedded system tested at Hardware-In-the-Loop (HIL) level. The random sequences were able to alter the system functionality observed at the prove-out test.
2004-07-19
Technical Paper
2004-01-2293
Edward Hodgson, Allison Bender, Joel Goldfarb, Gregory Quinn, Catherine Thibaud-Erkey, Fred Sribnik
An important, though often unstated, requirement to achieve NASA’s strategic goals will be an Extravehicular Activity (EVA) system that will let future astronauts work safely and effectively at the chosen destinations without imposing unacceptable burdens on the astronauts or the mission systems that support them. Past studies have shown that this may present an insurmountable challenge if pursued with current technologies and system design concepts. With funding from the NASA Institute for Advanced Concepts (NIAC), Hamilton Sundstrand has been studying a conceptual architecture for future EVA systems to meet this challenge. The Chameleon Suit concept shifts the EVA design paradigm from one in which the pressure garment and life support system are separate, largely independent subsystems to one in which the EVA system integrates distributed life support functions with the pressure suit.
2010-10-17
Technical Paper
2010-36-0520
Delia Dimitriu, Dragos Munteanu, Octavian Pleter
This paper is assessing two methods that can be used in assessing the airport noise capacity when new operational practices are implemented at a certain airport. The example given is CDA-continuous descent approach implemented at Bucharest Henri Coanda International airport in Romania. A review of the main operational practices related to CDO (Continuous Descent Operations) with relevance for noise and emissions reduction, shows the importance of working in a team when implementing new operational practices, as well as the need to access data either through FDR (flight data recorder) or from measurements. - The example selected explains the difficulties one can have to extract FDR data. Although the authors of this paper benefitted from FDR from TAROM, the Romanian national airline, it was difficult to be extracted, so the assessment of the airport noise capacity focused on monitoring and measurements undertaken under the flight path.
1999-10-19
Technical Paper
1999-01-5629
Martin Kraus, Rudolf Heinzinger, Hans-Christoph Oelker
Integration of ground-based testing into the airborne testing process is presented in terms of an advanced test and analysis concept. Based on the discussion, that running a simulator is less expensive than performing a test flight, means of combining both methodologies are being presented and discussed. The idea is to perform selected tests on ground-based facilities under test flight conditions. This is called Virtual Flight Testing. For explanation of this idea an example is given and a representative result is presented. Another main pillar of this advanced test and analysis concept is on-line analysis. A recent tool for this purpose is on-line simulation, which is introduced with a brief overview together with an illustrative example. The paper gives an introduction into DASA’s efforts to increase efficiency of the testing process. The main goal is an early feedback of test information into the design process in order to improve this process.
1999-10-19
Technical Paper
1999-01-5551
Michael Vujcich, Terry Scharton
Combining the quasi-static loads, workmanship verification, and model validation tests of aerospace hardware into a single vibration test sequence can considerably reduce schedule and cost. The enabling factor in the implementation of the combined dynamic testing approach is the measurement of the dynamic forces exerted on the test item by the shaker. The dynamic testing of the QuikSCAT spacecraft is discussed as an example of a successful combined loads, workmanship, and model validation test program.
1999-10-19
Technical Paper
1999-01-5550
Daniel Anthony, Terry Scharton, Albert Leccese
A novel direct acoustic test was performed on the Quik- SCAT spacecraft at Ball Aerospace Technology Corporation (BATC) in Boulder, Colorado, in October 1998. The QuikSCAT spacecraft was designed and built by BATC in an accelerated, one-year, program managed by the NASA Goddard Space Flight Center. The spacecraft carries the SeaWinds scatterometer developed by the Jet Propulsion Laboratory to measure the near-surface wind speed over Earth’s oceans. Instead of conducting the acoustic test with the spacecraft in a reverberant room, as is the usual practice, the test was conducted with the spacecraft mounted on a shaker slip-table in a nearly anechoic, vibration test cell. The spacecraft was surrounded with a three-meter high ring of large, electro-dynamic speakers, spaced approximately 1.3 meters away from the two-meter diameter, 900 kg. spacecraft. The thirty-one speaker cabinets were driven with 40,000 rms watts of audio amplifier power.
2011-06-13
Technical Paper
2011-38-0064
Jafar Alzaili, David Hammond
The objective of this work is to investigate the thin water film characteristics by performing a range of experiments for different icing conditions. Our focus is on the SLD conditions where the droplets are larger and other effects like splashing and re-impingement could occur. Three features for the thin water film have been studied experimentally: the water film velocity, wave celerity and its wavelength. The experiments are performed in the icing facilities at Cranfiled University. The stability of the water film for the different conditions has been studied to find a threshold for transient from continues water film to non-continues form. A new semi-empirical method is introduced to estimate the water film thickness based on the experimental data of water film velocity in combination of theoretical analysis of water film dynamics. The outcome of this work could be implemented in SLD icing simulation but more analysis is needed.
2011-06-13
Technical Paper
2011-38-0055
Richard Moser, Roger Gent
The European Union (EU) ‘Clean Sky’ [1] Joint Technology Initiative (JTI) is a research programme aimed at developing breakthrough technologies which will minimise the impact of aviation on the environment. Within this, the System for Green Operations (SGO) Integrated Technology Demonstrator (ITD) looks to improve aircraft operation through management of energy and mission trajectory. As part of the SGO ITD, a series of environmental icing tests have been conducted on an ice protected, acoustically protected, electrically powered, scoop intake and channel. The range of conditions tested included in-flight icing (CS-25 Appendix C, same as 14 CFR 25), super-cooled large droplets (proposed 14 CFR 25 Appendix O, [2]), snow and ice crystal conditions as well as ground icing in freezing fog conditions.
2010-10-06
Technical Paper
2010-36-0282
Andre Nogueira Sousa, Antonio Rafael da Silva Filho, Igor Machado Malaquias, Julio Cesar Santana Fernandes, Leandro Souza de Moura Lima
In this article, a methodology for flight tests to determine the stall speed is adapted for UAVs (unmanned aerial vehicles). The UAV is equipped with a system of data acquisition to store the variables related to the stall speed during the flight of the aircraft. Next the data is processed to determine the stall characteristics of the aircraft and consequently its stall speed. The results are compared with analytical calculations to validate the proposed methodology.
2004-11-16
Technical Paper
2004-01-3237
Nivaldo Cristofani, Sandro Aparecido Baldacim, Carlos do Nascimento Santos, José Rui Lautenschlager
In the past, civil aircraft were assessed for electromagnetic compatibility in terms of the ability of onboard systems to coexist without incompatibility problems. However with the advent of electronic into safety critical systems on a new generation of civil aircraft, the aviation authorities became concerned about the potential interference effects of High Interference Radiated Fields (HIRF). The HIRF is generated by emission groups located in aircrafts, airports, ship/boat, such as antennas, radar, navigation/communications instruments, transmitters, among others. The results of interaction of the external electromagnetic fields with aircraft structure and electric-electronic systems herein installed can be generate a high intensity of voltage and current transients, occasioning hazard to electronic equipments and operational reliability.
2004-11-16
Technical Paper
2004-01-3236
Sandro Aparecido Baldacim, Nivaldo Cristofani, Carlos do Nascimento Santos, José Rui Lautenschlager
Lightning is a high voltage and high current phenomenon and it originates by build up of electrical charge in the air or, more commonly, in clouds. It is constituted of an electric current peak of short duration (0,5 ms) and high intensity (200 kA), followed by a low intensity (400 A) but high duration (1s) periods. The lightning effects in aircraft can be divided in two groups: direct effects (physical effects such as melting, rupture, damage of surfaces and structures due to conduction of lightning current or high power magnetic force) and indirect effects (electromagnetic fields generating levels of transient voltage and current on interconnecting wiring and cable leads within the equipment circuits eventually damaging internal components).
2004-07-19
Technical Paper
2004-01-2573
Randy Ashford
The F/A-22 Raptor Environmental Control System/Thermal Management System (ECS/TMS) software is a real-time digital control system application. The system is comprised of 4 separate computer software configuration items (CSCI). Verification & Validation (V& V) activities of such a system is complex and performed in stages. The process begins with structured design and analysis techniqes and culminates with actual flight test. This paper provides an overview of the V& V effort to perform the formal software qualification testing to flight certify this software. First, an overview of the system and software architecture is provided. Then each level of testing is described. Development and problem report metrics are shown. Finally, lessons learned are presented.
2004-07-19
Technical Paper
2004-01-2542
Josef B. Simeonsson, Muhsin Ezer
Studies are being performed to investigate the feasibility of surface enhanced Raman scattering (SERS) spectrometry for monitoring volatile organic compounds (VOCs) in air. The focus of these studies has been on the development and characterization of substrate materials that can be used for SERS measurements. The studies have shown that substrates can be fabricated that provide high SERS sensitivity and selectivity. Substrates include Au or Ag nanoparticles immobilized on silica or deposited on paper supports. Measurements of a model compound have shown that enhancements as high as 1010 to 1012 can be achieved. Several VOC analytes have been investigated by SERS detection approaches, including indole, dimethyl sulfide, quinoline and benzoic acid. Studies have shown that substrates based on immobilized Au or Ag nanoparticles can be modified with surface coatings to enhance their SERS response.
2004-07-19
Technical Paper
2004-01-2541
James D. Tatara, Jay L. Perry
Since the beginning of the crewed space exploration program, the National Aeronautics and Space Administration (NASA) recognized the need to monitor the composition of a spacecraft cabin atmosphere. Typically, major constituent monitoring has been limited to nitrogen, oxygen, carbon dioxide, and water vapor. For the International Space Station, mass spectroscopy was selected as the baseline technology for this task. Recently, new techniques for monitoring major atmospheric constituents have matured commercially making them viable for crewed spacecraft applications. These techniques have advantages over the mass spectroscopy and electrochemically-based instruments used on board the ISS and Shuttle. Fast laser diode oxygen analysis, solid-state infrared carbon dioxide detection, and thin-film capacitive humidity detection are among the emerging techniques.
2011-06-13
Technical Paper
2011-38-0101
Regina Kuznetsova
This paper presents the test method and results from ice impact testing conducted on representative S-76D™ Helicopter Tail Rotor (TR) blade and TR control system assemblies. Full scale ice impact tests on the leading edge of the tail rotor blade paddle, pitch links, and a pitch beam were conducted to demonstrate sufficient residual strength for continued safe operation following a potential ice strike. During testing the tail rotor system remained stationary with centrifugal force (CF) simulated by stiffening the tail rotor blade with spring loading at the bolted joint. The ice pieces were shot at the blade/control specimen at an equivalent forward velocity of ice shedding from an aircraft traveling at 155 knots (1.0 VNE; 261.61 ft/s) plus an equivalent forward velocity of the blade given the rotational velocity at the tip (670 ft/s @ 99.4% TR Nr). Additional shots were conducted to define the relationship between impact energy and projectile fracture mode.
1959-01-01
Technical Paper
590051
J. M. Clark, G. C. Lawrason
RADIATION can produce almost instantaneous failure of modern aircraft lubricants, tests at Southwest Research Institute show. Two types of failures demonstrated are rapid viscosity rise and loss of heat conductivity. Furthermore, it was found that lubricants can become excessively corrosive under high-level radiation. Generally speaking, the better lubricants appeared to improve in performance while marginal ones deteriorated to a greater extent under radiation. When the better lubricants were subjected to static irradiation prior to the deposition test, there was a minor increase in deposition number as the total dose was increased.
2007-07-09
Technical Paper
2007-01-3142
Michael S. Roberts, Mary E. Hummerick, Sharon L. Edney, Patricia A. Bisbee, Michael R. Callahan, Sandy Loucks,, Karen D. Pickering, John C. Sager
This work describes the microbiological assessment and materials compatibility of a silver-based biocide as an alternative to iodine for the Crew Exploration Vehicle (CEV) and future spacecraft potable water systems. In addition to physical and operational anti-microbial counter-measures, the prevention of microbial growth, biofilm formation, and microbiologically induced corrosion in water distribution and storage systems requires maintenance of a biologically-effective, residual biocide concentration in solution and on the wetted surfaces of the system. Because of the potential for biocide depletion in water distribution systems and the development of acquired biocide resistance within microbial populations, even sterile water with residual biocide may, over time, support the growth and/or proliferation of bacteria that pose a risk to crew health and environmental systems.
2007-09-17
Technical Paper
2007-01-3788
K. Rokhsaz, L. K. Kliment
Some of the methods used for experimental detection and examination of wake vortices are presented. The aim of the article is to provide the reader a brief overview of the available methods. The material is divided into two major sections, one dealing with methods used primarily in the laboratory, and the second part devoted to those used in field operations. Over one hundred articles are cited and briefly discussed.
2009-07-12
Technical Paper
2009-01-2410
B. M. Shaughnessy, P. Eccleston
The Mid-Infrared Instrument (MIRI) is one of four scientific instruments on the James Webb Space Telescope (JWST) observatory, scheduled for launch in 2014. It will provide unique capabilities to probe the deeply dust-enshrouded regions of the Universe, investigating the history of star formation both near and far. The MIRI is the coldest instrument on the observatory. Its thermal design is driven by requirements to cool an Optics Module (OM) to below 15.5 K and detectors within this to below 6.7 K with a stability of <10 mK over 1000 seconds. The OM is accommodated within the JWST Integrated Science instrument Module (ISIM) which is cooled passively to between 32 and 40 K. The instrument temperatures are achieved by a combination of thermal isolation of the OM and the ISIM supplemented with active cooling of the OM by a dedicated cryo-cooler.
2009-07-12
Technical Paper
2009-01-2470
David Zuniga, Steven D. Hornung, Jon P. Haas, John C. Graf
Fire detection, post fire atmospheric monitoring, fire extinguishing, and post fire atmospheric cleaning are vital components of a spacecraft fire response system, Preliminary efforts focused on the technology evaluation of fire detection, post fire atmospheric monitoring and post fire cleanup systems under realistic conditions are described in this paper. While the primary objective of testing is to determine the performance of a smoke mitigation filter, supplemental evaluations measuring the smoke-filled chamber handheld Commercial Off The Shelf (COTS) atmospheric monitoring devices (combustion product monitors) are conducted. The test chamber consists of a 1.4 cubic meter (50 cu. ft.) volume containing a smoke generator.
2009-07-12
Technical Paper
2009-01-2430
E. Sacchi, A. Ferrero, M. Munì, E. Massa
The market pressure towards compression of costs and schedule time affects all the programs activities. For the campaigns of thermal verification in particular, this trend results in the recurring request for shorter and inexpensive test verification campaigns. This paper presents the Thales Alenia Space-Italia experience in the field of the thermal balance tests, by comparing the test philosophies and approaches followed on various Navigation and Earth Observation satellites, for which TAS-I was fully responsible of the thermal control and of the relevant verification. The objectives of the comparison are to highlight the critical choices and the relevant lessons learnt in the test definition process, and to promote the standardization and optimization of the thermal verification campaigns, with particular regard to: Evaluation of the uncertainty confidence level and of its evolution along the program cycle.
2009-07-12
Technical Paper
2009-01-2490
David B. Hirsch, James H. Williams, Jon P. Haas, Harold D. Beeson, Gary A. Ruff, Michael D. Pedley
The Orion Crew Exploration Vehicle Module (CM) is being designed to operate in an atmosphere of up to 30% oxygen at a pressure of 10.2 psia for lunar missions. Spacecraft materials selection is based on a normal gravity upward flammability test conducted in a closed chamber under the worst expected conditions of pressure and oxygen concentration. Material flammability depends on both oxygen concentration and pressure, but since oxygen concentration is the primary driver, all materials are certified in the 30% oxygen, 10.2 psia environment. Extensive data exist from the Shuttle Program at this condition, which used essentially the same test methodology as the Constellation Program is currently using. Raising the partial pressure of oxygen in the Orion CM immediately before reentry, while maintaining the total cabin pressure at 14.7 psia, has been proposed to maximize the time the crew is able to breathe cabin air after splashdown.
2009-07-12
Technical Paper
2009-01-2492
Sheng-Yen Hsu, Ya-Ting Tseng, James S. T'ien
Two detailed numerical models for flame growth and spread over solid surfaces are solved. For the three-dimensional model of steady spread over thin solids, the computations have included the variations of pressure, oxygen percentage and gravity in buoyant flows and pressure, oxygen percentage and flow velocity in purely forced flow in zero gravity. The overall comparisons of spread rates with experiments are reasonable but there is not enough data to perform a thorough comparison on the extinction limits. The computed results provide detailed flame structures in these different conditions that also reveal the difference between flames in a buoyant flow and in a forced flow. The ignition and flame growth processes along a thick solid surface are studied by a two-dimensional transient model which has a quasi-steady gas phase and an unsteady solid phase.
2008-06-29
Technical Paper
2008-01-2088
Sara McAllister, Carlos Fernandez-Pello, Gary Ruff, David Urban
Material flammability is an important factor in determining the pressure and composition (fraction of oxygen and nitrogen) of the atmosphere in the habitable volume of exploration vehicles and habitats. The method chosen in this work to quantify material flammability is by its ease of ignition and the minimum (critical) radiant heat flux for ignition. Piloted ignition delay tests were conducted in the Forced Ignition and Spread Test (FIST) apparatus subject to various atmospheric pressures and oxygen concentrations. The ignition delay time was measured as the time it takes a combustible material to ignite after it has been exposed to an external heat flux. In these tests, polymethylmethacylate (PMMA) was exposed to an oxidizer flow velocity of 1 m/s and a range of externally applied heat flux levels from 8 to 14 kW/m2.
2008-06-29
Technical Paper
2008-01-2124
David Champagne, Salvatore R. DiNardi, Richard Hagar
The atmosphere aboard submarines can pose many risks to the health and safety of the crew. Significant effort is applied throughout a submarine's life cycle to manage these risks. The enclosed atmosphere of a submarine represents a unique environment where crewmembers can be exposed to low levels of trace contaminants for long periods. For the purpose of monitoring, atmospheric constituents are divided into three categories: onboard monitoring required (Type 1), retrospective monitoring required (Type 2), and no monitoring required (Type 3). Categorization is determined by the Submarine Atmosphere Advisory Board (SAAB) based upon the Submarine Atmosphere Health Assessment Program (SAHAP) ranking system, an algorithm that takes into account risk of exposure and outcome of exposure. The SAAB comprises representatives from undersea medical, toxicological and occupational health activities with technical consultation from the submarine engineering community.
2008-06-29
Technical Paper
2008-01-2122
H. Pasquier, L. Perrin, J. Pauwels
The French-Indian MEGHA-TROPIQUES satellite is devoted to the atmospheric research. Data collected by the satellite will improve our knowledge on the water cycle contribution to the climate dynamic in the tropical atmosphere and our understanding of the processes linked to the tropical convection. The payload is made of MADRAS (developed by CNES and ISRO) and of two instruments provided by CNES: SAPHIR and SCARAB. The paper presents: the thermal control design of the two CNES instruments SAPHIR and SCARAB, taking into account the mechanical and scientific constraints. This design is based on a passive thermal control, on uses of heating power for cold cases or safe mode. This thermal design is today analyzed and the main results will be shown; the validation logic is now defined and instrument thermal tests are in preparation. These instrument thermal tests will be done in the second part of 2008.
2008-06-29
Technical Paper
2008-01-2153
Marco Molina, Alberto Franzoso, Alessandro Bursi, Francisco Romera Fernandez, Guido Barbagallo
The future Mars rover thermal design presents a unique challenge to the thermal engineers: the need arises for a thermal control system able to keep rover elements within their operational and non-operational temperature ranges in the face of extreme environmental conditions, characterized by broad day/night temperature excursions, cold biased conditions and long periods in standby modes induced by dust storms. A thermal device is needed, which allows the removal of excess heat from dissipating units during the Martian day and to keep them above their minimum operational/survival temperature during night. Moreover the scientific goals introduce strict requirements in terms of allowable internal components temperature ranges and thermal stability, which the candidate device has to fulfill against wide-ranging power dissipation modes. Such a device has been called Variable Thermal Conductance Device, or ‘Heat Switch’.
2005-07-11
Technical Paper
2005-01-2859
Johannes Dagner, Marc Hainke, Jochen Friedrich
The development of the MSL Furnace Inserts (FIs) and Sample-Cartridge Assemblies (SCAs) Thermal Modeling Tool (TMT) is presented. The TMT is based on the software package CrysVUn. In this paper, we report details of the validation procedure of the Thermal Mathematical Models (TMM) of the FIs Low Gradient Furnace (LGF) and Solidification and Quenching Furnace (SQF). The TMMs are verified for several stationary and time-dependent processes using different SCAs. The agreement with experimental measurements at 12 thermocouples inside the SCA is in each case better than 2%.
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