Science.gov

Sample records for aerobot thermo-mechanical subsystem

  1. Experimental Results for Titan Aerobot Thermo-Mechanical Subsystem Development

    NASA Technical Reports Server (NTRS)

    Hall, Jeffrey L.; Jones, J. A.; Kerzhanovich, V. V.; Lachenmeier, T.; Mahr, P.; Pauken, M.; Plett, G. A.; Smith, L.; VanLuvender, M. L.; Yavrouian, A. H.

    2006-01-01

    This paper describes experimental results from a development program focused in maturing Titan aerobot technology in the areas of mechanical and thermal subsystems. Results from four key activities are described: first, a cryogenic balloon materials development program involving coupon and cylinder tests and culminating in the fabrication and testing of an inflated 4.6 m long prototype blimp at 93 K; second, a combined lab experiment and numerical simulation effort to assess potential problems resulting from radioisotope thermal generator waste heat generation near an inflated blimp; third, an aerial deployment and inflation development program consisting of laboratory and helicopter drop tests on a near full scale (11 m long) prototype blimp; and fourth, a proof of concept experiment demonstrating the viability of using a mechanically steerable high gain antenna on a floating blimp to perform direct to Earth telecommunications from Titan. The paper provides details on all of these successful activities and discusses their impact on the overall effort to produce mature systems technology for future Titan aerobot missions.

  2. Venus Aerobot Multisonde Mission

    NASA Technical Reports Server (NTRS)

    Cutts, James A.; Kerzhanovich, Viktor; Balaram, J. Bob; Campbell, Bruce; Gershaman, Robert; Greeley, Ronald; Hall, Jeffery L.; Cameron, Jonathan; Klaasen, Kenneth; Hansen, David M.

    1999-01-01

    Robotic exploration of Venus presents many challenges because of the thick atmosphere and the high surface temperatures. The Venus Aerobot Multisonde mission concept addresses these challenges by using a robotic balloon or aerobot to deploy a number of short lifetime probes or sondes to acquire images of the surface. A Venus aerobot is not only a good platform for precision deployment of sondes but is very effective at recovering high rate data. This paper describes the Venus Aerobot Multisonde concept and discusses a proposal to NASA's Discovery program using the concept for a Venus Exploration of Volcanoes and Atmosphere (VEVA). The status of the balloon deployment and inflation, balloon envelope, communications, thermal control and sonde deployment technologies are also reviewed.

  3. Aerobot Autonomy Architecture

    NASA Technical Reports Server (NTRS)

    Elfes, Alberto; Hall, Jeffery L.; Kulczycki, Eric A.; Cameron, Jonathan M.; Morfopoulos, Arin C.; Clouse, Daniel S.; Montgomery, James F.; Ansar, Adnan I.; Machuzak, Richard J.

    2009-01-01

    An architecture for autonomous operation of an aerobot (i.e., a robotic blimp) to be used in scientific exploration of planets and moons in the Solar system with an atmosphere (such as Titan and Venus) is undergoing development. This architecture is also applicable to autonomous airships that could be flown in the terrestrial atmosphere for scientific exploration, military reconnaissance and surveillance, and as radio-communication relay stations in disaster areas. The architecture was conceived to satisfy requirements to perform the following functions: a) Vehicle safing, that is, ensuring the integrity of the aerobot during its entire mission, including during extended communication blackouts. b) Accurate and robust autonomous flight control during operation in diverse modes, including launch, deployment of scientific instruments, long traverses, hovering or station-keeping, and maneuvers for touch-and-go surface sampling. c) Mapping and self-localization in the absence of a global positioning system. d) Advanced recognition of hazards and targets in conjunction with tracking of, and visual servoing toward, targets, all to enable the aerobot to detect and avoid atmospheric and topographic hazards and to identify, home in on, and hover over predefined terrain features or other targets of scientific interest. The architecture is an integrated combination of systems for accurate and robust vehicle and flight trajectory control; estimation of the state of the aerobot; perception-based detection and avoidance of hazards; monitoring of the integrity and functionality ("health") of the aerobot; reflexive safing actions; multi-modal localization and mapping; autonomous planning and execution of scientific observations; and long-range planning and monitoring of the mission of the aerobot. The prototype JPL aerobot (see figure) has been tested extensively in various areas in the California Mojave desert.

  4. Advanced Aerobots for Scientific Exploration

    NASA Technical Reports Server (NTRS)

    Behar, Alberto; Raymond, Carol A.; Matthews, Janet B.; Nicaise, Fabien; Jones, Jack A.

    2010-01-01

    The Picosat and Uninhabited Aerial Vehicle Systems Engineering (PAUSE) project is developing balloon-borne instrumentation systems as aerobots for scientific exploration of remote planets and for diverse terrestrial purposes that can include scientific exploration, mapping, and military surveillance. The underlying concept of balloon-borne gondolas housing outer-space-qualified scientific instruments and associated data-processing and radio-communication equipment is not new. Instead, the novelty lies in numerous design details that, taken together, make a PAUSE aerobot smaller, less expensive, and less massive, relative to prior aerobots developed for similar purposes: Whereas the gondola (including the instrumentation system housed in it) of a typical prior aerobot has a mass of hundreds of kilograms, the mass of the gondola (with instrumentation system) of a PAUSE aerobot is a few kilograms.

  5. Optimizing Aerobot Exploration of Venus

    NASA Technical Reports Server (NTRS)

    Ford, Kevin S.

    1997-01-01

    Venus Flyer Robot (VFR) is an aerobot; an autonomous balloon probe designed for remote exploration of Earth's sister planet in 2003. VFR's simple navigation and control system permits travel to virtually any location on Venus, but it can survive for only a limited duration in the harsh Venusian environment. To help address this limitation, we develop: (1) a global circulation model that captures the most important characteristics of the Venusian atmosphere; (2) a simple aerobot model that captures thermal restrictions faced by VFR at Venus; and (3) one exact and two heuristic algorithms that, using abstractions (1) and (2), construct routes making the best use of VFR's limited lifetime. We demonstrate this modeling by planning several small example missions and a prototypical mission that explores numerous interesting sites recently documented in the plane tary geology literature.

  6. Planning Flight Paths of Autonomous Aerobots

    NASA Technical Reports Server (NTRS)

    Kulczycki, Eric; Elfes, Alberto; Sharma, Shivanjli

    2009-01-01

    Algorithms for planning flight paths of autonomous aerobots (robotic blimps) to be deployed in scientific exploration of remote planets are undergoing development. These algorithms are also adaptable to terrestrial applications involving robotic submarines as well as aerobots and other autonomous aircraft used to acquire scientific data or to perform surveying or monitoring functions.

  7. On-Board Perception System For Planetary Aerobot Balloon Navigation

    NASA Technical Reports Server (NTRS)

    Balaram, J.; Scheid, Robert E.; T. Salomon, Phil

    1996-01-01

    NASA's Jet Propulsion Laboratory is implementing the Planetary Aerobot Testbed to develop the technology needed to operate a robotic balloon aero-vehicle (Aerobot). This earth-based system would be the precursor for aerobots designed to explore Venus, Mars, Titan and other gaseous planetary bodies. The on-board perception system allows the aerobot to localize itself and navigate on a planet using information derived from a variety of celestial, inertial, ground-imaging, ranging, and radiometric sensors.

  8. Thermo-Mechanical Pumps for Superfluid Helium

    SciTech Connect

    Kaiser, G.; Schumann, B.; Stangl, R.; Binneberg, A.; Wobst, E.

    2004-06-23

    In Alpha Magnetic Spectrometer-02 (AMS-02) experiment a large scale superconducting magnet separates charged particles coming from cosmic radiation. Two thermo-mechanical pumps (TMP), operating by use of the Fountain-effect, will be used to supply the current leads and the magnet coil after quench with superfluid helium. These TMP are currently under development at ILK Dresden. Due to the applications the TMP are required to pump a mass flow of 0.2 g/s. After introduction into the basic principles essential for TMP function, we report on the development and tests of the TMP for AMS-02.

  9. Integrated Turbopump Thermo-Mechanical Design and Analysis Tools

    NASA Astrophysics Data System (ADS)

    Platt, Mike

    2002-07-01

    This viewgraph presentation provides information on the thermo-mechanical design and analysis tools used to control the steady and transient thermo-mechanical effects which drive life, reliability, and cost. The thermo-mechanical analysis tools provide upfront design capability by effectively leveraging existing component design tools to analyze and control: fits, clearance, preload; cooling requirements; stress levels, LCF (low cycle fatigue) limits, and HCF (high cycle fatigue) margin.

  10. Aerobots and Hydrobots for Planetary Exploration

    NASA Technical Reports Server (NTRS)

    Barrett, Chris

    2000-01-01

    In this new Millennium, NASA will expand its presence in space. Many new planetary bodies have been discovered, and some previously known bodies are now believed to have oceans. We now know of 66 moons in our own Solar System, one with an atmosphere, 16 with water ice or oceans, and 5 with both. In addition, we now know of 20 extra-solar planets. In order to expand our presence in space and explore in a cost effective manner, we need a repertoire of new types of planetary exploration vehicles to explore both atmospheres and oceans. To address this need a spectrum of new classes of vehicles are being developed. These include aerobots and hydrobots, and incorporate Department of Defense miniaturization developments and smart materials. This paper outlines: the remarkable miniaturization developments applicable to robotic vehicles for the exploration of planetary atmospheres and oceans; Aerobots, the vehicles designed for planetary atmospheric exploration; Hydrobots, those designed for planetary ocean exploration; planetary atmospheric data; and Europa ocean exploration missions.

  11. Robust and Opportunistic Autonomous Science for a Potential Titan Aerobot

    NASA Technical Reports Server (NTRS)

    Gaines, Daniel M.; Estlin, Tara; Schaffer, Steve; Castano, Rebecca; Elfes, Alberto

    2010-01-01

    We are developing onboard planning and execution technologies to provide robust and opportunistic mission operations for a potential Titan aerobot. Aerobot have the potential for collecting a vast amount of high priority science data. However, to be effective, an aerobot must address several challenges including communication constraints, extended periods without contact with Earth, uncertain and changing environmental conditions, maneuverability constraints and potentially short-lived science opportunities. We are developing the AerOASIS system to develop and test technology to support autonomous science operations for a potential Titan Aerobot. The planning and execution component of AerOASIS is able to generate mission operations plans that achieve science and engineering objectives while respecting mission and resource constraints as well as adapting the plan to respond to new science opportunities. Our technology leverages prior work on the OASIS system for autonomous rover exploration. In this paper we describe how the OASIS planning component was adapted to address the unique challenges of a Titan Aerobot and we describe a field demonstration of the system with the JPL prototype aerobot.

  12. Venus Aerobot Surface Science Imaging System (VASSIS)

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    1999-01-01

    The VASSIS task was to design and develop an imaging system and container for operation above the surface of Venus in preparation for a Discovery-class mission involving a Venus aerobot balloon. The technical goals of the effort were to: a) evaluate the possible nadir-viewed surface image quality as a function of wavelength and altitude in the Venus lower atmosphere, b) design a pressure vessel to contain the imager and supporting electronics that will meet the environmental requirements of the VASSIS mission, c) design and build a prototype imaging system including an Active-Pixel Sensor camera head and VASSIS-like optics that will meet the science requirements. The VASSIS science team developed a set of science requirements for the imaging system upon which the development work of this task was based.

  13. Thermo-mechanical characterization of silicone foams

    SciTech Connect

    Rangaswamy, Partha; Smith, Nickolaus A.; Cady, Carl M.; Lewis, Matthew W.

    2015-10-01

    Cellular solids such as elastomeric foams are used in many structural applications to absorb and dissipate energy, due to their light weight (low density) and high energy absorption capability. In this paper we will discuss foams derived from S5370, a silicone foam formulation developed by Dow Corning. In the application presented, the foam is consolidated into a cushion component of constant thickness but variable density. A mechanical material model developed by Lewis (2013), predicts material response, in part, as a function of relative density. To determine the required parameters for this model we have obtained the mechanical response in compression for ambient, cold and hot temperatures. The variable density cushion provided samples sufficient samples so that the effect of sample initial density on the mechanical response could be studied. The mechanical response data showed extreme sensitivity to relative density. We also observed at strains corresponding to 1 MPa a linear relationship between strain and initial density for all temperatures. Samples taken from parts with a history of thermal cycling demonstrated a stiffening response that was a function of temperature, with the trend of more stiffness as temperature increased above ambient. This observation is in agreement with the entropic effects on the thermo-mechanical behavior of silicone polymers. In this study, we present the experimental methods necessary for the development of a material model, the testing protocol, analysis of test data, and a discussion of load (stress) and gap (strain) as a function of sample initial densities and temperatures

  14. Near-field NanoThermoMechanical memory

    SciTech Connect

    Elzouka, Mahmoud; Ndao, Sidy

    2014-12-15

    In this letter, we introduce the concept of NanoThermoMechanical Memory. Unlike electronic memory, a NanoThermoMechanical memory device uses heat instead of electricity to record, store, and recover data. Memory function is achieved through the coupling of near-field thermal radiation and thermal expansion resulting in negative differential thermal resistance and thermal latching. Here, we demonstrate theoretically via numerical modeling the concept of near-field thermal radiation enabled negative differential thermal resistance that achieves bistable states. Design and implementation of a practical silicon based NanoThermoMechanical memory device are proposed along with a study of its dynamic response under write/read cycles. With more than 50% of the world's energy losses being in the form of heat along with the ever increasing need to develop computer technologies which can operate in harsh environments (e.g., very high temperatures), NanoThermoMechanical memory and logic devices may hold the answer.

  15. An aerobot for global in situ exploration of Titan

    NASA Technical Reports Server (NTRS)

    Hall, Jeffery L.; Kerzhanovich, V. V.; Yavrouian, A. H.; Jones, J. A.; White, C. V.; Dudik, B. A.; Plett, G. A.; Menella, J.; Elfes, A.

    2004-01-01

    This paper describes the design and component testing of an aerobot that would be capable of global in situ exploration of Saturn's moon, Titan, over a 6 to 12 month mission lifetime. The proposed aerobot is a propeller-driven, buoyant vehicle that resembles terrestrial airships. However, the extremely cold Titan environment requires the use of cryogenic materials of construction and careful thermal design for protection of temperature-sensitive payload elements. Multiple candidate balloon materials have been identified based on extensive laboratory testing at 77 K. The most promising materials to date are laminates comprised of polyester fabrics and/or films with areal densities in the range of 40-100 g/m2. The aerobot hull is a streamlined ellipsoid 14 meters in length with a maximum diameter of 3 meters. The enclosed volume of 60 m3 is sufficient to float a mass of 234 kg at a maximum altitude of 8 km at Titan. Forward and aft ballonets are located inside the hull to enable the aerobot to descend to the surface while preserving a fully inflated streamlined shape. Altitude changes are effected primarily through thrust vectoring of the twin main propellers, with pressure modulated buoyancy change via the ballonets available as a slower backup option. A total of 100 W of electrical power is provided to the vehicle by a radioisotope power supply. Up to half of this power is available to the propulsion system to generate a top flight speed in the range of 1-2 m/s. This speed is expected to be greater than the near surface winds at Titan, enabling the aerobot to fly to and hover over targets of interest. A preliminary science payload has been devised for the aerobot to give it the capability for aerial imaging of the surface, atmospheric observations and sampling, and surface sample acquisition and analysis. Targeting, hovering, surface sample acquisition and vehicle health monitoring and automatic safing actions will all require significant on-board autonomy due to

  16. Meshfree simulations of thermo-mechanical ductile fracture

    NASA Astrophysics Data System (ADS)

    Simkins, D. C.; Li, S.

    2006-08-01

    In this work, a meshfree method is used to simulate thermo-mechanical ductile fracture under finite deformation. A Galerkin meshfree formulation incorporating the Johnson-Cook damage model is implemented in numerical computations. We are interested in the simulation of thermo-mechanical effects on ductile fracture under large scale yielding. A rate form adiabatic split is proposed in the constitutive update. Meshfree techniques, such as the visibility criterion, are used to modify the particle connectivity based on evolving crack surface morphology. The numerical results have shown that the proposed meshfree algorithm works well, the meshfree crack adaptivity and re-interpolation procedure is versatile in numerical simulations, and it enables us to predict thermo-mechanical effects on ductile fracture.

  17. Strengthening of Aluminum Alloy 2219 by Thermo-mechanical Treatment

    NASA Astrophysics Data System (ADS)

    Li, Xifeng; Lei, Kun; Song, Peng; Liu, Xinqin; Zhang, Fei; Li, Jianfei; Chen, Jun

    2015-10-01

    Strengthening of aluminum alloy 2219 by thermo-mechanical treatment has been compared with artificial aging. Three simple deformation modes including pre-stretching, compression, and rolling have been used in thermo-mechanical treatment. The tensile strength, elongation, fracture feature, and precipitated phase have been investigated. The results show that the strengthening effect of thermo-mechanical treatment is better than the one of artificial aging. Especially, the yield strength significantly increases with a small decrease of elongation. When the specimen is pre-stretched to 8.0%, the yield strength reaches 385.0 MPa and increases by 22.2% in comparison to the one obtained in aging condition. The maximum tensile strength of 472.4 MPa is achieved with 4.0% thickness reduction by compression. The fracture morphology reveals locally ductile and brittle failure mechanism, while the coarse second-phase particles distribute on the fracture surface. The intermediate phases θ″ or θ' orthogonally precipitate in the matrix after thermo-mechanical treatment. As compared to artificial aging, the cold plastic deformation increases distribution homogeneity and the volume fraction of θ'' or θ' precipitates. These result in a better strengthening effect.

  18. Trajectory Generation and Path Planning for Autonomous Aerobots

    NASA Technical Reports Server (NTRS)

    Sharma, Shivanjli; Kulczycki, Eric A.; Elfes, Alberto

    2007-01-01

    This paper presents global path planning algorithms for the Titan aerobot based on user defined waypoints in 2D and 3D space. The algorithms were implemented using information obtained through a planner user interface. The trajectory planning algorithms were designed to accurately represent the aerobot's characteristics, such as minimum turning radius. Additionally, trajectory planning techniques were implemented to allow for surveying of a planar area based solely on camera fields of view, airship altitude, and the location of the planar area's perimeter. The developed paths allow for planar navigation and three-dimensional path planning. These calculated trajectories are optimized to produce the shortest possible path while still remaining within realistic bounds of airship dynamics.

  19. Universal mechanism of thermo-mechanical deformation in metallic glasses

    SciTech Connect

    Dmowski, W.; Tong, Y.; Iwashita, T.; Egami, Takeshi; Yokoyama, Y.

    2015-02-11

    Here we investigated the atomistic structure of metallic glasses subjected to thermo-mechanical creep deformation using high energy x-ray diffraction and molecular dynamics simulation. The experiments were performed in-situ, at high temperatures as a time dependent deformation in the elastic regime, and ex-situ on samples quenched under stress. We show that all the anisotropic structure functions of the samples undergone thermo-mechanical creep can be scaled into a single curve, regardless of the magnitude of anelastic strain, stress level and the sign of the stress, demonstrating universal behavior and pointing to unique atomistic unit of anelastic deformation. The structural changes due to creep are strongly localized within the second nearest neighbors, involving only a small group of atoms.

  20. Universal mechanism of thermo-mechanical deformation in metallic glasses

    DOE PAGESBeta

    Dmowski, W.; Tong, Y.; Iwashita, T.; Egami, Takeshi; Yokoyama, Y.

    2015-02-11

    Here we investigated the atomistic structure of metallic glasses subjected to thermo-mechanical creep deformation using high energy x-ray diffraction and molecular dynamics simulation. The experiments were performed in-situ, at high temperatures as a time dependent deformation in the elastic regime, and ex-situ on samples quenched under stress. We show that all the anisotropic structure functions of the samples undergone thermo-mechanical creep can be scaled into a single curve, regardless of the magnitude of anelastic strain, stress level and the sign of the stress, demonstrating universal behavior and pointing to unique atomistic unit of anelastic deformation. The structural changes due tomore » creep are strongly localized within the second nearest neighbors, involving only a small group of atoms.« less

  1. Thermo-Mechanical Processing Parameters for the INCONEL ALLOY 740

    SciTech Connect

    Ludtka, G.M.; Smith, G.

    2007-11-19

    In 2000, a Cooperative Research and Development Agreement (CRADA) was undertaken between the Oak Ridge National Laboratory (ORNL) and the Special Metals Corporation (SMC) to determine the mechanical property response of the IN740 alloy to help establish thermo-mechanical processing parameters for the use of this alloy in supercritical and ultra-critical boiler tubes with the potential for other end uses. SMC had developed an alloy, commercially known as INCONEL alloy 740, which exhibited various beneficial physical, mechanical, and chemical properties. As part of SMC's on-going efforts to optimize this alloy for targeted boiler applications there was a need to develop an understanding of the thermo-mechanical response of the material, characterize the resulting microstructure from this processing, and possibly, utilize models to develop the appropriate processing scheme for this product.

  2. Thermal and thermo-mechanical simulation of laser assisted machining

    SciTech Connect

    Germain, G.; Dal Santo, P.; Lebrun, J. L.; Bellett, D.; Robert, P.

    2007-04-07

    Laser Assisted Machining (LAM) improves the machinability of materials by locally heating the workpiece just prior to cutting. The heat input is provided by a high power laser focused several millimeters in front of the cutting tool. Experimental investigations have confirmed that the cutting force can be decreased, by as much as 40%, for various materials (tool steel, titanium alloys and nickel alloys). The laser heat input is essentially superficial and results in non-uniform temperature profiles within the depth of the workpiece. The temperature field in the cutting zone is therefore influenced by many parameters. In order to understand the effect of the laser on chip formation and on the temperature fields in the different deformation zones, thermo-mechanical simulation were undertaken. A thermo-mechanical model for chip formation with and without the laser was also undertaken for different cutting parameters. Experimental tests for the orthogonal cutting of 42CrMo4 steel were used to validate the simulation via the prediction of the cutting force with and without the laser. The thermo-mechanical model then allowed us to highlight the differences in the temperature fields in the cutting zone with and without the laser. In particular, it was shown that for LAM the auto-heating of the material in the primary shear zone is less important and that the friction between the tool and chip also generates less heat. The temperature fields allow us to explain the reduction in the cutting force and the resulting residual stress fields in the workpiece.

  3. Thermo-mechanical behavior of epoxy shape memory polymer foams

    NASA Astrophysics Data System (ADS)

    Di Prima, M. A.; Lesniewski, M.; Gall, K.; McDowell, D. L.; Sanderson, T.; Campbell, D.

    2007-12-01

    Shape memory polymer foams have significant potential in biomedical and aerospace applications, but their thermo-mechanical behavior under relevant deformation conditions is not well understood. In this paper we examine the thermo-mechanical behavior of epoxy shape memory polymer foams with an average relative density of nearly 20%. These foams are deformed under conditions of varying stress, strain, and temperature. The glass transition temperature of the foam was measured to be approximately 90 °C and compression and tensile tests were performed at temperatures ranging from 25 to 125 °C. Various shape recovery tests were used to measure recovery properties under different thermo-mechanical conditions. Tensile strain to failure was measured as a function of temperature to probe the maximum recovery limits of the foam in both temperature and strain space. Compression tests were performed to examine compressibility of the material as a function of temperature; these foams can be compacted as much as 80% and still experience full strain recovery over multiple cycles. Furthermore, both tensile strain to failure tests and cyclic compression recovery tests revealed that deforming at a temperature of 80 °C maximizes macroscopic strain recovery. Deformation temperatures above or below this optimal value lead to lower failure strains in tension and the accumulation of non-recoverable strains in cyclic compression. Micro-computed tomography (micro-CT) scans of the foam at various compressed states were used to understand foam deformation mechanisms. The micro-CT studies revealed the bending, buckling, and collapse of cells with increasing compression, consistent with results from published numerical simulations.

  4. Electro-thermo-mechanical model for bulk acoustic wave resonators.

    PubMed

    Rocas, Eduard; Collado, Carlos; Mateu, Jordi; Orloff, Nathan D; Aigner, Robert; Booth, James C

    2013-11-01

    We present the electro-thermo-mechanical constitutive relations, expanded up to the third order, for a BAW resonator. The relations obtained are implemented into a circuit model, which is validated with extensive linear and nonlinear measurements. The mathematical analysis, along with the modeling, allows us to identify the dominant terms, which are the material temperature derivatives and two intrinsic nonlinear terms, and explain, for the first time, all observable effects in a BAW resonator by use of a unified physical description. Moreover, the terms that are responsible for the second-harmonic generation and the frequency shift with dc voltage are shown to be the same. PMID:24158294

  5. Coupled Thermo-Mechanical Analyses of Dynamically Loaded Rubber Cylinders

    NASA Technical Reports Server (NTRS)

    Johnson, Arthur R.; Chen, Tzi-Kang

    2000-01-01

    A procedure that models coupled thermo-mechanical deformations of viscoelastic rubber cylinders by employing the ABAQUS finite element code is described. Computational simulations of hysteretic heating are presented for several tall and short rubber cylinders both with and without a steel disk at their centers. The cylinders are compressed axially and are then cyclically loaded about the compressed state. The non-uniform hysteretic heating of the rubber cylinders containing a steel disk is presented. The analyses performed suggest that the coupling procedure should be considered for further development as a design tool for rubber degradation studies.

  6. Continuous damage parameter calculation under thermo-mechanical random loading

    PubMed Central

    Nagode, Marko

    2014-01-01

    The paper presents a method on how the mean stress effect on fatigue damage can be taken into account under an arbitrary low cycle thermo-mechanical loading. From known stress, elastoplastic strain and temperature histories the cycle amplitudes and cycle mean values are extracted and the damage parameter is computed. In contrast to the existing methods the proposed method enables continuous damage parameter computation without the need of waiting for the cycles to close. The limitations of the standardized damage parameters are thus surpassed. The damage parameters derived initially for closed and isothermal cycles assuming that the elastoplastic stress–strain response follows the Masing and memory rules can now be used to take the mean stress effect into account under an arbitrary low cycle thermo-mechanical loading. The method includes:•stress and elastoplastic strain history transformation into the corresponding amplitude and mean values;•stress and elastoplastic strain amplitude and mean value transformation into the damage parameter amplitude history;•damage parameter amplitude history transformation into the damage parameter history. PMID:26150939

  7. Thermo-mechanical properties of polyester mortar using recycled PET

    SciTech Connect

    Rebeiz, K.S.; Craft, A.P.

    1997-07-01

    The thermo-mechanical properties of polyester mortar (PM) using unsaturated polyester resins based on recycled PET are investigated in this paper (the recycled PET waste is mainly obtained from used plastic beverage bottles). The use of recycled PET in PM formulation is important because it helps produce good quality PM at a relatively low cost, save energy and alleviate an environmental problem posed by plastic wastes. PM construction applications include the repair of dams, piers, runways, bridges and other structures. Test results show that the effective use of PM overlays on portland cement concrete slabs is best achieved by utilizing flexible resins with low modulus and high elongation capacity at failure. The use of flexible resins in PM production is especially important in situations involving large thermal movements.

  8. Thermo-mechanical process for treatment of welds

    SciTech Connect

    Malik, R K

    1980-03-01

    Benefits from thermo-mechanical processing (TMP) of austenitic stainless steel weldments, analogous to hot isostatic pressing (HIP) of castings, most likely result from compressive plastic deformation, enhanced diffusion, and/or increased dislocation density. TMP improves ultrasonic inspectability of austenitic stainless steel welds owing to: conversion of cast dendrites into equiaxed austenitic grains, reduction in size and number of stringers and inclusions, and reduction of delta ferrite content. TMP induces structural homogenization and healing of void-type defects and thus contributes to an increase in elongation, impact strength, and fracture toughness as well as a significant reduction in data scatter for these properties. An optimum temperature for TMP or HIP of welds is one which causes negligible grain growth and an acceptable reduction in yield strength, and permits healing of porosity.

  9. Thermo-Mechanical Analyses of Dynamically Loaded Rubber Cylinders

    NASA Technical Reports Server (NTRS)

    Johnson, Arthur R.; Chen, Tzi-Kang

    2002-01-01

    Thick rubber components are employed by the Army to carry large loads. In tanks, rubber covers road wheels and track systems to protect roadways. It is difficult for design engineers to simulate the details of the hysteretic heating for large strain viscoelastic deformations. In this study, an approximation to the viscoelastic energy dissipated per unit time is investigated for use in estimating mechanically induced viscoelastic heating. Coupled thermo-mechanical simulations of large cyclic deformations of rubber cylinders are presented. The cylinders are first compressed axially and then cyclically loaded about the compressed state. Details of the algorithm and some computational issues are discussed. The coupled analyses are conducted for tall and short rubber cylinders both with and without imbedded metal disks.

  10. A Transversely Isotropic Thermo-mechanical Framework for Oil Shale

    NASA Astrophysics Data System (ADS)

    Semnani, S. J.; White, J. A.; Borja, R. I.

    2014-12-01

    The present study provides a thermo-mechanical framework for modeling the temperature dependent behavior of oil shale. As a result of heating, oil shale undergoes phase transformations, during which organic matter is converted to petroleum products, e.g. light oil, heavy oil, bitumen, and coke. The change in the constituents and microstructure of shale at high temperatures dramatically alters its mechanical behavior e.g. plastic deformations and strength, as demonstrated by triaxial tests conducted at multiple temperatures [1,2]. Accordingly, the present model formulates the effects of changes in the chemical constituents due to thermal loading. It is well known that due to the layered structure of shale its mechanical properties in the direction parallel to the bedding planes is significantly different from its properties in the perpendicular direction. Although isotropic models simplify the modeling process, they fail to accurately describe the mechanical behavior of these rocks. Therefore, many researchers have studied the anisotropic behavior of rocks, including shale [3]. The current study presents a framework to incorporate the effects of transverse isotropy within a thermo-mechanical formulation. The proposed constitutive model can be readily applied to existing finite element codes to predict the behavior of oil shale in applications such as in-situ retorting process and stability assessment in petroleum reservoirs. [1] Masri, M. et al."Experimental Study of the Thermomechanical Behavior of the Petroleum Reservoir." SPE Eastern Regional/AAPG Eastern Section Joint Meeting. Society of Petroleum Engineers, 2008. [2] Xu, B. et al. "Thermal impact on shale deformation/failure behaviors---laboratory studies." 45th US Rock Mechanics/Geomechanics Symposium. American Rock Mechanics Association, 2011. [3] Crook, AJL et al. "Development of an orthotropic 3D elastoplastic material model for shale." SPE/ISRM Rock Mechanics Conference. Society of Petroleum Engineers

  11. MABVAP: One Step Closer to an Aerobot Mission to Mars

    NASA Technical Reports Server (NTRS)

    Kerzhanovich, V. V.; Cutts, J. A.; Bachelder, A. D.; Cameron, J. M.; Hall, J. L.; Patzold, J. D.; Quadrelli, M. B.; Yavrouian, A. H.; Cantrell, J. A.; Lachenmeier, T. T.; Smith, M. G.

    1999-01-01

    Lighter-than-air planetary missions continued attract growing interest in Mars exploration due to unique combination of proximity to the surface and mobility that far surpasses capability of surface vehicles. Following the experience with the Sojourner rover and subsequent development of powerful rovers for Mars 2003 and 2005 missions it became clear that on Mars surface rover mobility is quite restricted. Realistic travel distances may be limited to tens of kilometers per year on relatively obstacle-free plains and a few kilometers or less on the more rugged terrains. Many areas on Mars will be inaccessible to rovers. Several concepts for a Mars aerobot (robotic balloon) mission have been pursued in the last decade. Additional information is contained in the original extended abstract.

  12. Opto-thermo-mechanical analysis for the FAME Observatory

    NASA Astrophysics Data System (ADS)

    Sokolsky, Larry; Ambrose, Jay

    2004-01-01

    The Full-Sky Astrometric Mapping Explorer (FAME) instrument was designed to be an extremely accurate star mapper. To map the entire sky, the earth-orbiting FAME satellite rotates about its spin axis every 40 minutes, and uses solar pressure to precess about the spin axis every 40 days. The instrument had two apertures, separated by 84.3 degrees, allowing a star to be imaged twice in one rotation with about a 10 minute delay. This delay enables the elimination of most measurement errors. The light enters an aperture, bounces off of a compound fold flat mirror, (2 ULE fold flats bonded together at an 84.3 degree angle), passes through a Cassegrain telescope, and is imaged by the focal plane. The requirement for the fold flat"s dimensional stability is severe - the variation in the angle between the flats (basic angle) must be held to be held to 10 μarcsec during the 10 minute period between the first and second time a star is imaged. This paper presents a transient opto-thermo-mechanical analysis of the optical system.

  13. Thermo-Mechanical Processing and Properties of a Ductile Iron

    SciTech Connect

    Syn, C.K.; Lesuer, R.R.; Sherby, O.D.

    1997-07-14

    Thermo-mechanical processing of ductile irons is a potential method for enhancing their mechanical properties. A ductile cast iron containing 3.6% C, 2.6% Si and 0.045% Mg was continuously hot-and-warm rolled or one-step press-forged from a temperature in the austenite range (900{degrees}C-1100{degrees}C) to a temperature below the A, temperature. Various amounts of reduction were used (from 60% to more than 90%) followed by a short heat ent at 600`C. The heat ent lead to a structure of fine graphite in a matrix of ferrite and carbides. The hot-and- warm worked materials developed a pearlitic microstructure while the press-forged material developed a spheroidite-like carbide microstructure in the matrix. Cementite-denuded ferrite zones were developed around graphite stringers in the hot-and-warm worked materials, but such zones were absent in the press-forged material. Tensile properties including tensile strength and total elongation were measured along the direction parallel and transverse to the rolling direction and along the direction transverse to the press-forging direction. The tensile ductility and strength both increased with a decrease in the amount of hot-and-warm working. The press- forged materials showed higher strength (645 MPa) than the hot-and-warrn worked materials (575 MPa) when compared at the same ductility level (22% elongation).

  14. Thermo-mechanical coupling of faults and mantle shear zones

    NASA Astrophysics Data System (ADS)

    Lambert, Valere; Barbot, Sylvain

    2016-04-01

    Paleo-seismological records suggest non-steady and potentially periodic trends in slip rates over time scales of the order of millennia. It is unclear whether the variability of recurrence times is due to fault processes alone or if they are modulated by off-fault deformation. Theoretical and numerical modeling of fault kinematics from geodetic data have enabled an explosion of new findings about the mechanics of the earthquake cycle. However, these models have been mostly confined to processes along the interface of a fault. Therefore many sources of off-fault deformation, such as thermoelasticity and viscoelasticity, cannot yet be accounted for in the earthquake cycle. Here, we couple fault kinematics and viscoelastic deformation within shear zones using the integral method to simulate unified earthquake cycles that combine fault and off-fault processes. We consider the modulation of slip rates along a fault within the brittle layer due to strain in a viscoelastic substrate beneath the brittle-ductile transition. By implementing a thermally-activated rheology accounting for thermal diffusion, we investigate the thermo-mechanical coupling of faults and mantle shear zones and its implications for earthquake recurrence.

  15. Unravelling columnar joints temperatures: a thermo-mechanical experimental approach

    NASA Astrophysics Data System (ADS)

    Lavallée, Yan; Lamur, Anthony; Iddon, Fiona E.; Kendrick, Jackie E.; Hornby, Adrian J.; Eggertson, Gudjon H.; Von Aulock, Felix W.; Wadsworth, Fabian B.

    2016-04-01

    Columnar joints are a widespread, spectacular volcanic phenomenon representing a complex cracking pattern induced by contraction of the lava upon cooling. The hexagonal geometry results from the complex interaction between heat dissipation, contraction and tensile fracturing of the material. While the formation mechanism is nowadays fairly well constrained, very little is known on the temperature at which these features form. Here, we present the results of a novel type of thermo-mechanical experiment, in which the ends of 16 mm rods of basalt were locked into position during cooling at different rates. We monitored the stress build-up and temperature within the samples in order to constrain the temperature of columnar jointing. Our experiments were applied to basaltic rocks sampled on a lava flow at the base of Eyjafjallajoküll volcano in Iceland. Results demonstrate that thermal contraction upon cooling triggers microscopic fracturing (at ~820 °C) that quickly evolves into localised macroscopic fracturing at 750-780 °C. Striaes observed along fracture planes can hence be interpreted as the reflection of this two-stage fracture propagation dynamics. We emphasize that columnar jointing occurs well within the solid state of volcanic rocks, not in a molten regime. These results are supported by complementary analysis of the expansion coefficient of these lavas as well as strain-to-failure acquired during Brazilian tensile tests. The nonlinearity of the coefficient of expansion has important implications for the development of a permeable network. At higher temperatures, micro-fracturing is caused by a quasi-linear coefficient of expansion, leading to a small increase in permeability. As cooling occurs, the coefficient of expansion drops increasingly rapidly, leading to an increasingly faster developing permeable network, which is controlled in-part by the scale of the columns that influences crack aperture opening. Our findings hence have implications in volcanic

  16. A unified creep-plasticity model suitable for thermo-mechanical loading

    NASA Technical Reports Server (NTRS)

    Slavik, D.; Sehitoglu, H.

    1988-01-01

    An experimentally based unified creep-plasticity constitutive model was implemented for 1070 steel. Accurate rate and temperature effects were obtained for isothermal and thermo-mechanical loading by incorporating deformation mechanisms into the constitutive equations in a simple way.

  17. GaN-on-diamond electronic device reliability: Mechanical and thermo-mechanical integrity

    NASA Astrophysics Data System (ADS)

    Liu, Dong; Sun, Huarui; Pomeroy, James W.; Francis, Daniel; Faili, Firooz; Twitchen, Daniel J.; Kuball, Martin

    2015-12-01

    The mechanical and thermo-mechanical integrity of GaN-on-diamond wafers used for ultra-high power microwave electronic devices was studied using a micro-pillar based in situ mechanical testing approach combined with an optical investigation of the stress and heat transfer across interfaces. We find the GaN/diamond interface to be thermo-mechanically stable, illustrating the potential for this material for reliable GaN electronic devices.

  18. GaN-on-diamond electronic device reliability: Mechanical and thermo-mechanical integrity

    SciTech Connect

    Liu, Dong; Sun, Huarui; Pomeroy, James W.; Kuball, Martin; Francis, Daniel; Faili, Firooz; Twitchen, Daniel J.

    2015-12-21

    The mechanical and thermo-mechanical integrity of GaN-on-diamond wafers used for ultra-high power microwave electronic devices was studied using a micro-pillar based in situ mechanical testing approach combined with an optical investigation of the stress and heat transfer across interfaces. We find the GaN/diamond interface to be thermo-mechanically stable, illustrating the potential for this material for reliable GaN electronic devices.

  19. Thermo-mechanical phenomena in high speed continuous casting processes

    NASA Astrophysics Data System (ADS)

    Park, Joong Kil

    Thermo-mechanical phenomena during continuous thin slab casting have been studied with the objectives of understanding the mechanism of mold crack formation, and the effect of mold design upon the mechanical behavior of the stand. To achieve these goals, several finite element models have been developed in conjunction with a series of industrial plant trials. First, an investigation of mold crack formation in thin slab casting was undertaken to elucidate the mechanism by which cracks develop and to evaluate possible solutions to the problem. Three-dimensional finite-element thermal-stress models were developed to predict temperature, distortion, and residual stress in thin-slab casting molds, comparing funnel-shaped to parallel molds. Mold wall temperatures were obtained from POSCO in Korea and analyzed to determine the corresponding heat-flux profiles in thin-slab molds. This data was utilized in an elastic-visco-plastic analysis to investigate the deformation of the molds in service for the two different mold shapes. The results of a metallurgical investigation of mold samples containing cracks were used together with the results of the mathematical models, to determine mechanisms and to suggest solutions for the formation of mold cracks. Large cyclic inelastic strains were found in the funnel transition region just below the meniscus, due to the slightly higher temperature at that location. The cracks appear to have propagated by thermal fatigue caused by major level fluctuations. Next, two-dimensional thermo-elastic-visco-plastic analysis was performed for a horizontal slice of the solidifying strand, which moves vertically down the mold during casting. The model calculates the temperature distributions, the stresses and the strains in the solidifying shell, and the air gap between the casting mold and the solidifying strand. Model predictions were verified with an analytical solution and plant trials that were carried out during billet casting at POSCO. The

  20. Seismo-thermo-mechanical modeling of subduction zone seismicity

    NASA Astrophysics Data System (ADS)

    van Dinther, Ylona; Gerya, Taras; Dalguer, Luis; Mai, Martin

    2014-05-01

    Recent megathrust earthquakes, e.g., the 2011 M9.0 Tohoku and the 2004 M9.2 Sumatra events, illustrated both their disastrous human and economic impact and our limited physical understanding of their spatial occurrence. To improve long-term seismic hazard assessment by overcoming the restricted direct observations in time and space, we developed a new numerical seismo-thermo-mechanical (STM) modeling approach. This approach may help to shed light onto the interaction between long-term subduction dynamics and deformation and associated short-term seismicity. Additional advantages of this STM approach include the physically consistent emergence of rupture paths, both on- and off-megathrust, and the inclusion of three key ingredients for seismic cycling --rate-dependent friction, slow tectonic loading, and visco-elastic relaxation--. The validation of this approach was accomplished through a comparison with a laboratory seismic cycle model (van Dinther et al., JGR, 2013a). A more realistic geometry and physical setup of the Southern Chilean margin showed that results also agree with a range of seismological, geodetic, and geological observations, albeit at lower coseismic speeds (van Dinther et al., JGR, 2013b). This setup also suggests that a) ~5% of cyclic deformation is being stored on the long-term, b) a self-consistent downdip transition zone between 350°C and 450°C arises from temperature-dependent viscosity, and c) megathrusts are weak (i.e., pore fluid pressures of ˜75% to 99% of that of solid pressures). After introducing the main features of this innovative approach, this study focuses on analyzing the spontaneous unstable rupturing of off-megathrust events. Shallow off-megathrust subduction events are important in terms of hazard assessment and coseismic energy budget. The characteristics of simulated normal events within the outer-rise and splay and normal antithetic events within the wedge resemble seismic and seismological observations in terms of

  1. Thermo-mechanical Model of the Dead Sea Transform

    NASA Astrophysics Data System (ADS)

    Sobolev, S. V.; Babeyko, A. Y.; Garfunkel, Z.

    2002-12-01

    The Dead Sea transform system (DST) is the boundary between the Arabian and African plates, where left-lateral transform motion has largely accommodated the opening of the Red Sea basin during the last 15-20 My. One of the key questions related to this plate boundary is whether the DST crosses the crust and mantle lithosphere, and how the rheologically different units composing the lithosphere interact during strong deformation? Another major question is how important is the rifting (transform-perpendicular extension) deformation component at the DST? We address these questions using the internally consistent finite element thermo-mechanical modelling of the lithospheric deformation constrained by high-resolution geophysical observations and especially by the recent geophysical data of the DESERT Project. From our modelling, we conclude that the DST lithospheric structure is controlled by the plate-scale transform displacement within a relatively cold and strong lithosphere. In such a lithosphere, shear strain is localized in a narrow (20-40 km wide) vertical decoupling zone (VDZ), which crosses the entire lithosphere and even continues into the asthenosphere. In the upper crust the deformation localizes at one or two major faults located at the top of this zone. The location of the VDZ is controlled by the temperature of the uppermost mantle prior to the transform motion. Most of the lithospheric structures imaged along the DESERT seismic line is explained by the 105 km transform motion combined with less than 4 km transform-perpendicular extension. Uplift of the Arabian Shield adjacent to the DST can be explained by young (<20 Ma) thinning of the lithosphere at and east of the plate boundary. Such lithospheric thinning is consistent with seismological observations, with the low present-day surface heat flow and with the high temperatures derived from mantle xenoliths brought up by Neogene-Quaternary basalts. Taking into account the timing of the onset of the

  2. Shape memory behavior of epoxy-based model materials: Tailoring approaches and thermo-mechanical modeling

    NASA Astrophysics Data System (ADS)

    Pandini, Stefano; Avanzini, Andrea; Battini, Davide; Berardi, Mario; Baldi, Francesco; Bignotti, Fabio

    2016-05-01

    A series of structurally related epoxy resins were prepared as model systems for the investigation of the shape memory response, with the aim to assess the possibility of tailoring their thermo-mechanical response and conveniently describing their strain evolution under triggering stimuli with a simple thermoviscoelastic model. The resins formulation was varied in order to obtain systems with controlled glass transition temperature and crosslink density. The shape memory response was investigated by means of properly designed thermo-mechanical cycles, which allowed to measure both the ability to fully recover the applied strain and to exert a stress on a confining medium. The results were also compared with the predictions obtained by finite element simulations of the thermo-mechanical cycle by the employ of a model whose parameters were implemented from classical DMA analysis.

  3. Application of Thermo-Mechanical Measurements of Plastic Packages for Reliability Evaluation of PEMS

    NASA Technical Reports Server (NTRS)

    Sharma, Ashok K.; Teverovsky, Alexander

    2004-01-01

    Thermo-mechanical analysis (TMA) is typically employed for measurements of the glass transition temperature (Tg) and coefficients of thermal expansion (CTE) in molding compounds used in plastic encapsulated microcircuits (PEMs). Application of TMA measurements directly to PEMs allows anomalies to be revealed in deformation of packages with temperature, and thus indicates possible reliability concerns related to thermo-mechanical integrity and stability of the devices. In this work, temperature dependencies of package deformation were measured in several types of PEMs that failed environmental stress testing including temperature cycling, highly accelerated stress testing (HAST) in humid environments, and bum-in (BI) testing. Comparison of thermo-mechanical characteristics of packages and molding compounds in the failed parts allowed for explanation of the observed failures. The results indicate that TMA of plastic packages might be used for quality evaluation of PEMs intended for high-reliability applications.

  4. Effects of Microstructural Variability on Thermo-Mechanical Properties of a Woven Ceramic Matrix Composite

    NASA Technical Reports Server (NTRS)

    Goldsmith, Marlana B.; Sankar, Bhavani V.; Haftka, Raphael T.; Goldberg, Robert K.

    2013-01-01

    The objectives of this paper include identifying important architectural parameters that describe the SiC/SiC five-harness satin weave composite and characterizing the statistical distributions and correlations of those parameters from photomicrographs of various cross sections. In addition, realistic artificial cross sections of a 2D representative volume element (RVE) are generated reflecting the variability found in the photomicrographs, which are used to determine the effects of architectural variability on the thermo-mechanical properties. Lastly, preliminary information is obtained on the sensitivity of thermo-mechanical properties to architectural variations. Finite element analysis is used in combination with a response surface and it is shown that the present method is effective in determining the effects of architectural variability on thermo-mechanical properties.

  5. Detailed exploration of Titan with a Montgolfiere aerobot

    NASA Astrophysics Data System (ADS)

    Spilker, T.; Tipex Team

    The International Cassini/Huygens (CH) mission has verified the expectation that Saturn's moon Titan offers many opportunities for studying high-priority planetary and astrobiology science objectives. CH results to date show that this world, though entirely alien in its frigid environment, presents an Earth-like and diverse appearance due to the relative balance of competing forces such as geology/tectonics, meteorology, aeronomy, and cosmic impacts. But with the limitations of a single Huygens probe, and a finite number of Cassini flybys limited in proximity and remote sensing resolution by Titan's thick atmosphere and hazes, there is much science to be done there after the CH mission has ended. Detailed exploration of Titan's surface and lower atmosphere, especially for astrobiological objectives, is best addressed by in situ investigations. The atmosphere and its hazes severely restrict orbital remote sensing: Titan cannot be mapped from orbit in the same manner as Mars, at (essentially) arbitrarily high resolution, and limited infrared (IR) windows allow only gross compositional interpretations. After CH indeed there will be further orbital investigations to be carried out, notably completion of the global mapping by Synthetic Aperture Radar and IR mapping spectrometry begun by CH, at the best resolutions practical from orbit. But to fully understand Titan as an evolving, planetary-scale body and an abode of preserved protobiological chemistry will require a platform that has access to, and mobility at, the surface and the lowest few kilometers of the atmosphere. The TiPEx study team weighed the options for Titan in situ exploration, and finds that a mission based on a Montgolfiere (a type of hot-air balloon) aerobot is the best candidate for post-CH exploration. Ground-based platforms of the type used to date on Mars are far too limited in range to sample the diversity of Titan, and do not adequately investigate the lower atmosphere. Titan's cold, dense

  6. Coupled infrared laser-thermo-mechanical response of RDX-PCTFE energetic aggregates

    NASA Astrophysics Data System (ADS)

    Brown, Judith A.; Zikry, M. A.

    2016-04-01

    A computational approach is developed to investigate the coupled phenomena of high frequency electromagnetic (EM) wave propagation, laser heat absorption, thermal conduction, and inelastic dynamic thermo-mechanical deformation in heterogeneous energetic materials. The method is used to study hot spot formation in RDX-PCTFE aggregates subjected to high strain rate loads and infrared laser irradiation. The approach couples Maxwell's equations with a dislocation density-based crystal plasticity formulation within a nonlinear finite-element approach to predict and understand thermo-mechanical response due to the interrelated effects of dielectric heating, adiabatic heating, thermal decomposition, and heat conduction. RDX crystalline interfaces and orientations, polymer binder, inelastic strains, dislocation-density evolution, and voids significantly affected the coupled EM-thermo-mechanical response. EM and thermo-mechanical mismatches at interfaces between RDX crystals, binder, and voids resulted in localized regions with high electric field and laser heat generation rates, which subsequently led to hot spot formation. It is predicted that incident laser intensity and plastic shear strain localization are the dominant mechanisms that lead to hot spot formation.

  7. Power Subsystem

    NASA Technical Reports Server (NTRS)

    Kluksdahl, Betsy

    1991-01-01

    Topics concerning the Common Lunar Lander are presented in view graph form and include: energy storage and power generation; electrical power distribution and control; pyrotechniques; input from other subsystems; and design refinement following vehicle integration.

  8. Thermo-mechanical pressurization of experimental faults in cohesive rocks during seismic slip

    NASA Astrophysics Data System (ADS)

    Violay, M.; Di Toro, G.; Nielsen, S.; Spagnuolo, E.; Burg, J. P.

    2015-11-01

    Earthquakes occur because fault friction weakens with increasing slip and slip rates. Since the slipping zones of faults are often fluid-saturated, thermo-mechanical pressurization of pore fluids has been invoked as a mechanism responsible for frictional dynamic weakening, but experimental evidence is lacking. We performed friction experiments (normal stress 25 MPa, maximal slip-rate ∼3 ms-1) on cohesive basalt and marble under (1) room-humidity and (2) immersed in liquid water (drained and undrained) conditions. In both rock types and independently of the presence of fluids, up to 80% of frictional weakening was measured in the first 5 cm of slip. Modest pressurization-related weakening appears only at later stages of slip. Thermo-mechanical pressurization weakening of cohesive rocks can be negligible during earthquakes due to the triggering of more efficient fault lubrication mechanisms (flash heating, frictional melting, etc.).

  9. Warm Forming of Aluminum Alloys using a Coupled Thermo-Mechanical Anisotropic Material Model

    SciTech Connect

    Abedrabbo, Nader; Pourboghrat, Farhang; Carsley, John E.

    2005-08-05

    Temperature-dependant anisotropic material models for two types of automotive aluminum alloys (5754-O and 5182-O) were developed and implemented in LS-Dyna as a user material subroutine (UMAT) for coupled thermo-mechanical finite element analysis (FEA) of warm forming of aluminum alloys. The anisotropy coefficients of the Barlat YLD2000 plane stress yield function for both materials were calculated for the range of temperatures 25 deg. C-260 deg. C. Curve fitting was used to calculate the anisotropy coefficients of YLD2000 and the flow stress as a function of temperature. This temperature-dependent material model was successfully applied to the coupled thermo-mechanical analysis of stretching of aluminum sheets and results were compared with experiments.

  10. Warm Forming of Aluminum Alloys using a Coupled Thermo-Mechanical Anisotropic Material Model

    NASA Astrophysics Data System (ADS)

    Abedrabbo, Nader; Pourboghrat, Farhang; Carsley, John E.

    2005-08-01

    Temperature-dependant anisotropic material models for two types of automotive aluminum alloys (5754-O and 5182-O) were developed and implemented in LS-Dyna as a user material subroutine (UMAT) for coupled thermo-mechanical finite element analysis (FEA) of warm forming of aluminum alloys. The anisotropy coefficients of the Barlat YLD2000 plane stress yield function for both materials were calculated for the range of temperatures 25°C-260°C. Curve fitting was used to calculate the anisotropy coefficients of YLD2000 and the flow stress as a function of temperature. This temperature-dependent material model was successfully applied to the coupled thermo-mechanical analysis of stretching of aluminum sheets and results were compared with experiments.

  11. Heat generation and thermo-mechanical effect modeling in longitudinally diode-pumped solid state lasers

    NASA Astrophysics Data System (ADS)

    Lakhdari, Fouad; Osmani, Ismahen; Tabet, Saida

    2015-09-01

    Thermal management in solid state laser is a challenge to the high power laser industry's ability to provide continued improvements in device and system performance. In this work an investigation of heat generation and thermo-mechanical effect in a high-power Nd:YAG and Yb:YAG cylindrical-type solid state laser pumped longitudinally with different power by fibre coupled laser diode is carried out by numerical simulation based on the finite element method (FEM). Impact of the dopant concentration on the power conversion efficiency is included in the simulation. The distribution of the temperature inside the lasing material is resolute according to the thermal conductivity. The thermo-mechanical effect is explored as a function of pump power in order to determine the maximum pumping power allowed to prevent the crystal's fracture. The presented simulations are in broad agreement with analytical solutions; provided that the boundary condition of the pump induced heat generation is accurately modelled.

  12. The development and production of thermo-mechanically forged tool steel spur gears

    NASA Technical Reports Server (NTRS)

    Bamberger, E. N.

    1973-01-01

    A development program to establish the feasibility and applicability of high energy rate forging procedures to tool steel spur gears was performed. Included in the study were relatively standard forging procedures as well as a thermo-mechanical process termed ausforming. The subject gear configuration utilized was essentially a standard spur gear having 28 teeth, a pitch diameter of 3.5 inches and a diametral pitch of 8. Initially it had been planned to use a high contact ratio gear design, however, a comprehensive evaluation indicated that severe forging problems would be encountered as a result of the extremely small teeth required by this type of design. The forging studies were successful in achieving gear blanks having integrally formed teeth using both standard and thermo-mechanical forging procedures.

  13. Thermo-mechanical simulation of guided waves in pipes excited by laser pulses

    NASA Astrophysics Data System (ADS)

    Lim, Hyeong Uk; Hong, Jung-Wuk

    2013-04-01

    Ultrasonic guided waves have been widely utilized for the structural health monitoring (SHM) of structural components such as plates and pipes. In particular, the noncontact excitation of the pipe surfaces using laser pulses has shown several advantages in experiments by eliminating the bonding process of the dielectric patches on the curved surfaces and the complicated interpretation of the temperature effect on the bonding layers. However, the numerical simulation of the methodology requires thermo-mechanical coupling and large-scale computation. Therefore, the numerical efficiency of the spatial partitioning by deploying thermo-mechanical elements and mechanical elements is investigated. Then, the laser excitation on the surface is modeled in the form of heat flux, and the generated wave forms are observed. The formation and propagation of the guided waves are also represented numerically.

  14. Description of the performances of a thermo-mechanical energy harvester using bimetallic beams

    NASA Astrophysics Data System (ADS)

    Arnaud, A.; Boughaleb, J.; Monfray, S.; Boeuf, F.; Cugat, O.; Skotnicki, T.

    2016-06-01

    Many recent researches have been focused on the development of thermal energy harvesters using thermo-mechanical or thermo-electrical coupling phenomena associated to a first-order thermodynamic transition. In the case of the bimetallic strip heat engine, the exploitation of the thermo-mechanical instability of bimetallic membranes placed in a thermal gradient enables to convert heat into kinetic energy. This paper is a contribution to the modeling and the comprehension of these heat engines. By restraining the study to the simply-supported bimetallic beams and using a Ritz approximation of the beam shape, this paper aims to give an analytical solution to the first mode of the composite beams and then to evaluate the efficiency of the harvesters exploiting these kinds of instability.

  15. Multiscale Simulation of Thermo-mechanical Processes in Irradiated Fission-reactor Materials

    SciTech Connect

    El-Azab, Anter

    2012-05-28

    This report contains a summary of progress made on the subtask area on phase field model development for microstructure evolution in irradiated materials, which was a part of the Computational Materials Science Network (CMSN) project entitled: Multiscale Simulation of Thermo-mechanical Processes in Irradiated Fission-reactor Materials. The model problem chosen has been that of void nucleation and growth under irradiation conditions in single component systems.

  16. Thermo-mechanical Response and Damping Behavior of Shape Memory Alloy-MAX Phase Composites

    NASA Astrophysics Data System (ADS)

    Kothalkar, Ankush Dilip; Benitez, Rogelio; Hu, Liangfa; Radovic, Miladin; Karaman, Ibrahim

    2014-05-01

    NiTi/Ti3SiC2 interpenetrating composites that combine two unique material systems—a shape memory alloy (SMA) and a MAX phase—demonstrating two different pseudoelastic mechanisms, were processed using spark plasma sintering. The goal of mixing these two material systems was to enhance the damping behavior and thermo-mechanical response of the composite by combining two pseudoelastic mechanisms, i.e., reversible stress-induced martensitic transformation in SMA and reversible incipient kink band formation in MAX phase. Equal volume fractions of equiatomic NiTi and Ti3SiC2 were used. Microstructural characterization was conducted using scanning electron microscopy to study the distribution of NiTi, Ti3SiC2, and remnant porosity in the composite. Thermo-mechanical testing in the form of thermal cycles under constant stress levels was performed in order to characterize shape memory behavior and thereby introducing residual stresses in the composites. Evolution of two-way shape memory effect was studied and related to the presence of residual stresses in the composites. Damping behavior, implying the energy dissipation per loading-unloading cycle under increasing compressive stresses, of pure NiTi, pure Ti3SiC2, as-sintered, and thermo-mechanically cycled (TC) NiTi/Ti3SiC2 composites, was investigated and compared to the literature data. In this study, the highest energy dissipation was observed for the TC composite followed by the as-sintered (AS) composite, pure NiTi, and pure Ti3SiC2 when compared at the same applied stress levels. Both the AS and TC composites showed higher damping up to 200 MPa stress than any of the metal—MAX phase composites reported in the literature to date. The ability to enhance the performance of the composite by controlling the thermo-mechanical loading paths was further discussed.

  17. Multiscale Thermo-Mechanical Design and Analysis of High Frequency and High Power Vacuum Electron Devices

    NASA Astrophysics Data System (ADS)

    Gamzina, Diana

    Diana Gamzina March 2016 Mechanical and Aerospace Engineering Multiscale Thermo-Mechanical Design and Analysis of High Frequency and High Power Vacuum Electron Devices Abstract A methodology for performing thermo-mechanical design and analysis of high frequency and high average power vacuum electron devices is presented. This methodology results in a "first-pass" engineering design directly ready for manufacturing. The methodology includes establishment of thermal and mechanical boundary conditions, evaluation of convective film heat transfer coefficients, identification of material options, evaluation of temperature and stress field distributions, assessment of microscale effects on the stress state of the material, and fatigue analysis. The feature size of vacuum electron devices operating in the high frequency regime of 100 GHz to 1 THz is comparable to the microstructure of the materials employed for their fabrication. As a result, the thermo-mechanical performance of a device is affected by the local material microstructure. Such multiscale effects on the stress state are considered in the range of scales from about 10 microns up to a few millimeters. The design and analysis methodology is demonstrated on three separate microwave devices: a 95 GHz 10 kW cw sheet beam klystron, a 263 GHz 50 W long pulse wide-bandwidth sheet beam travelling wave tube, and a 346 GHz 1 W cw backward wave oscillator.

  18. A thermo-mechanical stress prediction model for contemporary planar sodium sulfur (NaS) cells

    NASA Astrophysics Data System (ADS)

    Jung, Keeyoung; Colker, Jeffrey P.; Cao, Yuzhe; Kim, Goun; Park, Yoon-Cheol; Kim, Chang-Soo

    2016-08-01

    We introduce a comprehensive finite-element analysis (FEA) computational model to accurately predict the thermo-mechanical stresses at heterogeneous joints and components of large-size sodium sulfur (NaS) cells during thermal cycling. Quantification of the thermo-mechanical stress is important because the accumulation of stress during cell assembly and/or operation is one of the critical issues in developing practical planar NaS cells. The computational model is developed based on relevant experimental assembly and operation conditions to predict the detailed stress field of a state-of-the-art planar NaS cell. Prior to the freeze-and-thaw thermal cycle simulation, residual stresses generated from the actual high temperature cell assembly procedures are calculated and implemented into the subsequent model. The calculation results show that large stresses are developed on the outer surface of the insulating header and the solid electrolyte, where component fracture is frequently observed in the experimental cell fabrication process. The impacts of the coefficients of thermal expansion (CTE) of glass materials and the thicknesses of cell container on the stress accumulation are also evaluated to improve the cell manufacturing procedure and to guide the material choices for enhanced thermo-mechanical stability of large-size NaS cells.

  19. Assessing thermo-mechanical properties of the lithospheric mantle in Asia

    NASA Astrophysics Data System (ADS)

    Stolk, W.; Kaban, M. K.; Beekman, F.; Tesauro, M.; Cloetingh, S.

    2012-12-01

    Asia is a key natural laboratory for the study of active intra-continental deformation in response to the ongoing far-field collision of India and Eurasia. The resulting tectonic processes strongly depend on the thermo-mechanical structure of the lithosphere. However, the problem of the thermo-mechanical properties of the lithospheric mantle is complex and still not well resolved. While seismic studies give an indication of the heterogeneity of the mantle lithosphere it alone is insufficient to attribute these anomalies to thermal differences, since compositional difference may have a significant effect on observed wave velocities. Using solely gravity field analysis one cannot distinguish between e.g. stacked density anomalies or lateral density anomalies. Combining both datasets allows for a better insight into the mantle lithosphere, though the solution to the problem at hand remains non-unique. This study, of which the preliminary results will be presented here, attempts to gain insight into both compositional and thermal aspects of the mantle lithosphere in Asia. By combining a recent high resolution tomographic inversion with gravity field data, but without the assumption of a steady state mantle, a trade off between compositional and thermal effects can be made. Furthermore, susceptibility of the resulting model to small changes in parameter space can be obtained thus creating a 'playing field' for possible solutions to the thermo-mechanical problem. This 'playing field' can be further constrained by additional data from other sources, such as xenolith studies.

  20. Effect of Water on the Thermo-Mechanical Behavior of Carbon Cloth Phenolic

    NASA Technical Reports Server (NTRS)

    Sullivan, Roy M.; Stokes, Eric; Baker, Eric H.

    2011-01-01

    The results of thermo-mechanical experiments, which were conducted previously by one of the authors, are reviewed. The strain in the direction normal to the fabric plane was measured as a function of temperature for a variety of initial moisture contents and heating rates. In this paper, the general features of the thermo-mechanical response are discussed and the effect of heating rate and initial moisture content are highlighted. The mechanical interaction between the phenolic polymer and water trapped within its free volumes as the polymer is heated to high temperatures is discussed. An equation for the internal stresses which are generated within the polymer due to trapped water is obtained from the total stress expression for a binary mixture of polymer and water. Numerical solutions for moisture diffusion in the thermo-mechanical experiments were performed and the results of these solutions are presented. The results of the moisture diffusion solutions help to explain the effects of heating rate and moisture content on the strain behavior normal to the fabric plane.

  1. Interactive evolution concept for analyzing a rock salt cavern under cyclic thermo-mechanical loading

    NASA Astrophysics Data System (ADS)

    König, Diethard; Mahmoudi, Elham; Khaledi, Kavan; von Blumenthal, Achim; Schanz, Tom

    2016-04-01

    The excess electricity produced by renewable energy sources available during off-peak periods of consumption can be used e.g. to produce and compress hydrogen or to compress air. Afterwards the pressurized gas is stored in the rock salt cavities. During this process, thermo-mechanical cyclic loading is applied to the rock salt surrounding the cavern. Compared to the operation of conventional storage caverns in rock salt the frequencies of filling and discharging cycles and therefore the thermo-mechanical loading cycles are much higher, e.g. daily or weekly compared to seasonally or yearly. The stress strain behavior of rock salt as well as the deformation behavior and the stability of caverns in rock salt under such loading conditions are unknown. To overcome this, existing experimental studies have to be supplemented by exploring the behavior of rock salt under combined thermo-mechanical cyclic loading. Existing constitutive relations have to be extended to cover degradation of rock salt under thermo-mechanical cyclic loading. At least the complex system of a cavern in rock salt under these loading conditions has to be analyzed by numerical modeling taking into account the uncertainties due to limited access in large depth to investigate material composition and properties. An interactive evolution concept is presented to link the different components of such a study - experimental modeling, constitutive modeling and numerical modeling. A triaxial experimental setup is designed to characterize the cyclic thermo-mechanical behavior of rock salt. The imposed boundary conditions in the experimental setup are assumed to be similar to the stress state obtained from a full-scale numerical simulation. The computational model relies primarily on the governing constitutive model for predicting the behavior of rock salt cavity. Hence, a sophisticated elasto-viscoplastic creep constitutive model is developed to take into account the dilatancy and damage progress, as well as

  2. An Autonomy Architecture for Aerobot Exploration of the Saturnian Moon Titan

    NASA Technical Reports Server (NTRS)

    Elfes, Alberto; Hall, Jeffery L.; Kulczycki, Eric A.; Clouse, Daniel S.; Morfopoulos, Arin C.; Montgomery, James F.; Cameron, Jonathan M.; Ansar, Adnan; Machuzak, Richard J.

    2008-01-01

    The Huygens probe arrived at Saturn's moon Titan on January 14, 2005, unveiling a world that is radically different from any other in the Solar system. The data obtained, complemented by continuing observations from the Cassini spacecraft, show methane lakes, river channels and drainage basins, sand dunes, cryovolcanos and sierras. This has lead to an enormous scientific interest in a follow-up mission to Titan, using a robotic lighter-than-air vehicle (or aerobot). Aerobots have modest power requirements, can fly missions with extended durations, and have very long distance traverse capabilities. They can execute regional surveys, transport and deploy scientific instruments and in-situ laboratory facilities over vast distances, and also provide surface sampling at strategic science sites. This paper describes our progress in the development of the autonomy technologies that will be required for exploration of Titan. We provide an overview of the autonomy architecture and some of its key components. We also show results obtained from autonomous flight tests conducted in the Mojave desert.

  3. Airborne particle generation for optical tweezers by thermo-mechanical membrane actuators

    NASA Astrophysics Data System (ADS)

    Polster, T.; Leopold, S.; Hoffmann, M.

    2011-06-01

    This article presents a new approach for airborne particle generation for optical tweezers. The used element is a 500 nm thin aluminum nitride membrane with an integrated heating element. Thus the membrane works as thermo-mechanical actor. The membrane device is characterized concerning their mechanical and thermal behavior. Successful airborne particle generation is demonstrated with 10 μm silicon dioxide spheres. They are lifted up some 10th of μm from the membrane surface. The development and test of this device serves as starting point for experiments with optical tweezers in air.

  4. A thermo-mechanical analysis of a particle impact during thermal spraying

    NASA Astrophysics Data System (ADS)

    Danouni, Samir; Abdellah El-hadj, Abdellah; Zirari, Mounir; Belharizi, Mohamed

    2016-05-01

    The present study discusses the development of a simulation model of transient impact between a particle and a substrate. The equations for structural behavior are coupled with those of heat transfer, wherein material properties are taken as temperature dependent. The set of equations is solved with Ansys program using a direct coupling method. At first, structural model is solved without heat transfer. Then, coupled thermo-mechanical model is solved with and without thermoelastic effects. Computational results indicate that thermal consideration has significant effects on contact problem. In addition, it is shown that, themoelasticity consideration is crucial for simulating these problems to determine the structural and thermal parameters.

  5. Study of Carbide Evolution During Thermo-Mechanical Processing of AISI D2 Tool Steel

    NASA Astrophysics Data System (ADS)

    Bombac, D.; Fazarinc, M.; Podder, A. Saha; Kugler, G.

    2013-03-01

    The microstructure of a cold-worked tool steel (AISI D2) with various thermo-mechanical treatments was examined in the current study to identify the effects of these treatments on phases. X-ray diffraction was used to identify phases. Microstructural changes such as spheroidization and coarsening of carbides were studied. Thermodynamic calculations were used to verify the results of the differential thermal analysis. It was found that soaking temperature and time have a large influence on dissolution, precipitation, spheroidization, and coalescence of carbides present in the steel. This consequently influences the hot workability and final properties.

  6. User-defined Material Model for Thermo-mechanical Progressive Failure Analysis

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.

    2008-01-01

    Previously a user-defined material model for orthotropic bimodulus materials was developed for linear and nonlinear stress analysis of composite structures using either shell or solid finite elements within a nonlinear finite element analysis tool. Extensions of this user-defined material model to thermo-mechanical progressive failure analysis are described, and the required input data are documented. The extensions include providing for temperature-dependent material properties, archival of the elastic strains, and a thermal strain calculation for materials exhibiting a stress-free temperature.

  7. Correlation of microstructure and thermo-mechanical properties of a novel hydrogen transport membrane

    NASA Astrophysics Data System (ADS)

    Zhang, Yongjun

    A key part of the FutureGen concept is to support the production of hydrogen to fuel a "hydrogen economy," with the use of clean burning hydrogen in power-producing fuel cells, as well as for use as a transportation fuel. One of the key technical barriers to FutureGen deployment is reliable and efficient hydrogen separation technology. Most Hydrogen Transport Membrane (HTM) research currently focuses on separation technology and hydrogen flux characterization. No significant work has been performed on thermo-mechanical properties of HTMs. The objective of the thesis is to understand the structure-property correlation of HTM and to characterize (1) thermo mechanical properties under different reducing environments and thermal cycles (thermal shock), and (2) evaluate the stability of the novel HTM material. A novel HTM cermet bulk sample was characterized for its physical and mechanical properties at both room temperature and at elevated temperature up to 1000°C. Micro-structural properties and residual stresses were evaluated in order to understand the changing mechanism of the microstructure and its effects on the mechanical properties of materials. A correlation of the microstructural and thermo mechanical properties of the HTM system was established for both HTM and the substrate material. Mechanical properties of both selected structural ceramics and the novel HTM cermet bulk sample are affected mainly by porosity and microstructural features, such as grain size and pore size-distribution. The Young's Modulus (E-value) is positively correlated to the flexural strength for materials with similar crystallographic structure. However, for different crystallographic materials, physical properties are independent of mechanical properties. Microstructural properties, particularly, grain size and crystallographic structure, and thermodynamic properties are the main factors affecting the mechanical properties at both room and high temperatures. The HTM cermet behaves

  8. Thermo-mechanical characterization of nano filled and fiber reinforced brake friction materials

    NASA Astrophysics Data System (ADS)

    Singh, Tej; Patnaik, Amar; Satapathy, Bhabani K.

    2013-06-01

    Brake friction materials filled with multiwalled carbon nanotubes (MWCNT) and nanoclay have been fabricated and characterize for thermo-mechanical properties. Thermo gravimetric analysis (TGA) show that the stability of the friction composites increased with increase in MWCNT and nanoclay contents. Dynamic mechanical analysis (DMA) of the composite have been carried out to characterize the storage modulus (E'), loss modulus (E″) and damping factor (Tan δ) as a function of temperature. The storage and loss modulus show a maxima at lower content of MWCNT and nanoclay.

  9. Nanomechanical characterization of thermo-mechanical properties of irradiated zirconium with consideration of temperature and microstructure

    NASA Astrophysics Data System (ADS)

    Marsh, Jonathan T.

    Zirconium (Zr) and zirconium-alloys have been utilized in the nuclear industry for decades, most commonly in nuclear fuel cladding. The characteristics which make Zr ideal for these applications include: low density, high hardness, high ductility, and high corrosion resistance. Efforts have been made to further enhance these properties through the use of Zr-alloys, such as Zircaloy-2 and Zircaloy-4, which are made up 95-99% Zr by weight, with the remaining weight percentage being made of other metals (tin, niobium, nickel, iron, chromium). The performance of these materials directly influences the efficiency of the nuclear reactor and are thus of primary concern. While the properties of these materials alone have been studied extensively, the nuclear reactor environment itself serves to degrade or enhance these properties, depending on the situation. The coupled effect of irradiation, high temperature, and microstructure is not understood. Each of these aspects uniquely influence the thermo-mechanical properties of these Zr-based materials and a better understanding of these coupled phenomena is necessary to effectively and efficiently design these nuclear reactor components. The aim of the following work is to experimentally investigate the effect of these coupled phenomena on the thermo-mechanical properties and viscoplastic response of Zr.

  10. Damage mechanisms in PBT-GF30 under thermo-mechanical cyclic loading

    SciTech Connect

    Schaaf, A. De Monte, M. Hoffmann, C.; Vormwald, M.; Quaresimin, M.

    2014-05-15

    The scope of this paper is the investigation of damage mechanisms at microscopic scale on a short glass fiber reinforced polybutylene terephthalate (PBT-GF30) under thermo-mechanical cyclic loading. In addition the principal mechanisms are verified through micro mechanical FE models. In order to investigate the fatigue behavior of the material both isothermal strain controlled fatigue (ISCF) tests at three different temperatures and thermo-mechanical fatigue (TMF) tests were conducted on plain and notched specimens, manufactured by injection molding. The goal of the work is to determine the damage mechanisms occurring under TMF conditions and to compare them with the mechanisms occurring under ISCF. For this reason fracture surfaces of TMF and ISCF samples loaded at different temperature levels were analyzed using scanning electron microscopy. Furthermore, specimens that failed under TMF were examined on microsections revealing insight into both crack initiation and crack propagation. The findings of this investigation give valuable information about the main damage mechanisms of PBT-GF30 under TMF loading and serve as basis for the development of a TMF life estimation methodology.

  11. Thermo-mechanical simulations of CO2 laser-fused silica interactions

    NASA Astrophysics Data System (ADS)

    Doualle, T.; Gallais, L.; Cormont, P.; Hébert, D.; Combis, P.; Rullier, J.-L.

    2016-03-01

    CO2 laser heating of silica glass is used in many scientific and industrial applications. Particularly, localized CO2 laser heating of silica glass has demonstrated its ability to mitigate surface damage on optics used for high power laser applications. To develop such applications, the control of temperature, heat affected area, and resulting mechanical stresses are critical. Therefore, it is necessary to understand the silica transformation, the material ejection, and the thermo-mechanical stresses induced by the laser heating and subsequent cooling. In this paper, we detail the development of comprehensive thermo-mechanical numerical simulations of these physical processes, based on finite-element method. The approach is developed for 2D or 3D cases to tackle the case of a moving beam at the surface of the sample, and we particularly discuss the choice of the different parameters based on bibliographic inputs. The thermal and mechanical numerical results have been compared to different dedicated experimental studies: infrared thermography measurements at the surface of the irradiated area, optical profilometry measurements of the laser-processed sites, and photo-elastic measurements. Very consistent results are obtained between numerical and experimental results for the description of the temperature gradients, the material ejection, and the residual stresses.

  12. Thermo-Mechanical Modeling of Laser-Mig Hybrid Welding (lmhw)

    NASA Astrophysics Data System (ADS)

    Kounde, Ludovic; Engel, Thierry; Bergheau, Jean-Michel; Boisselier, Didier

    2011-01-01

    Hybrid welding is a combination of two different technologies such as laser (Nd: YAG, CO2…) and electric arc welding (MIG, MAG / TIG …) developed to assemble thick metal sheets (over 3 mm) in order to reduce the required laser power. As a matter of fact, hybrid welding is a lso used in the welding of thin materials to benefit from process, deep penetration and gap limit. But the thermo-mechanical behaviour of thin parts assembled by LMHW technology for railway cars production is far from being controlled the modeling and simulation contribute to the assessment of the causes and effects of the thermo mechanical behaviour in the assembled parts. In order to reproduce the morphology of melted and heat-affected zones, two analytic functions were combined to model the heat source of LMHW. On one hand, we applied a so-called "diaboloïd" (DB) which is a modified hyperboloid, based on experimental parameters and the analysis of the macrographs of the welds. On the other hand, we used a so-called "double ellipsoïd" (DE) which takes the MIG only contribution including the bead into account. The comparison between experimental result and numerical result shows a good agreement.

  13. Modelling the Thermo-Mechanical Behavior of Magnesium Alloys during Indirect Extrusion

    SciTech Connect

    Steglich, D.; Ertuerk, S.; Bohlen, J.; Letzig, D.; Brocks, W.

    2010-06-15

    One of the basic metal forming process for semi-finished products is extrusion. Since extrusion involves complex thermo-mechanical and multiaxial loading conditions resulting in large strains, high strain rates and an increase in temperature due to deformation, a proper yield criterion and hardening law should be used in the numerical modelling of the process. A phenomenological model based on a plastic potential has been proposed that takes strain, strain rate and temperature dependency on flow behaviour into consideration. A hybrid methodology of experiment and finite element simulation has been adopted in order to obtain necessary model parameters. The anisotropy/asymmetry in yielding was quantified by tensile and compression tests of specimens prepared from different directions. The identification of the corresponding model parameters was performed by a genetic algorithm. A fully coupled thermo-mechanical analysis has been used in extrusion simulations for calculation of the temperature field by considering heat fluxes and heat generated due to plastic deformation. The results of the approach adopted in this study appeared to be successful showing promising predictions of the experiments and thus may be extended to be applicable to other magnesium alloys or even other hcp metals.

  14. Development of Be/DSCu HIP bonding and thermo-mechanical evaluation

    NASA Astrophysics Data System (ADS)

    Hatano, T.; Kuroda, T.; Barabash, V.; Enoeda, M.

    2002-12-01

    The hot isostatic pressing (HIP) joining condition and interlayer materials for Be and DSCu joining have been examined. Based on the screening test results, two HIP conditions and interlayer materials were selected for mock-up fabrication. The first technology uses an Al-Si-Mg foil inserted between the beryllium tile coated by an Al layer and the DSCu heat sink coated by an Al/Ti/Cu layer at the HIP temperature of 555 °C. Another technology uses a DSCu heat sink coated by a pure Cu layer at the HIP temperature of 620 °C. The latter technology provided the highest strength of the Be/DSCu joints. Heating tests at heat flux of 5 MW/m 2 up to 1000 were performed to compare with thermo-mechanical performance. Though the HIP technology with the Al-Si-Mg foil had lower strength, the thermo-mechanical performance of the mock-up was better, than the performance of the mock-up with the pure Cu interlayer. The presence of the Al and Al-Si-Mg interlayers act as effective compliant layers between beryllium and DSCu.

  15. Finite Element Analysis of Thermo-Mechanical Properties of 3D Braided Composites

    NASA Astrophysics Data System (ADS)

    Jiang, Li-li; Xu, Guo-dong; Cheng, Su; Lu, Xia-mei; Zeng, Tao

    2014-04-01

    This paper presents a modified finite element model (FEM) to investigate the thermo-mechanical properties of three-dimensional (3D) braided composite. The effective coefficients of thermal expansion (CTE) and the meso-scale mechanical response of 3D braided composites are predicted. The effects of the braiding angle and fiber volume fraction on the effective CTE are evaluated. The results are compared to the experimental data available in the literature to demonstrate the accuracy and reliability of the present method. The tensile stress distributions of the representative volume element (RVE) are also outlined. It is found that the stress of the braiding yarn has a significant increase with temperature rise; on the other hand, the temperature change has an insignificant effect on the stress of the matrix. In addition, a rapid decrease in the tensile strength of 3D braided composites is observed with the increase in temperature. It is revealed that the thermal conditions have a significant effect on the strength of 3D braided composites. The present method provides an effective tool to predict the stresses of 3D braided composites under thermo-mechanical loading.

  16. Three-dimensional EBSD characterization of thermo-mechanical fatigue crack morphology in compacted graphite iron

    SciTech Connect

    Pirgazi, Hadi; Ghodrat, Sepideh; Kestens, Leo A.I.

    2014-04-01

    In cylinder heads made of compacted graphitic iron (CGI), heating and cooling cycles can lead to localized cracking due to thermo-mechanical fatigue (TMF). To meticulously characterize the complex crack path morphology of CGI under TMF condition, in relation to microstructural features and to find out how and by which mechanisms the cracks predominantly develop, three-dimensional electron back scattering diffraction (EBSD) was employed. Based on the precise quantitative microstructural analysis, it is found that graphite particles not only play a crucial role in the crack initiation, but also are of primary significance for crack propagation, i.e. crack growth is enhanced by the presence of graphite particles. Furthermore, the density of graphite particles on the fracture plane is more than double as high as in any other arbitrary plane of the structure. The obtained results did not indicate a particular crystallographic preference of fracture plane, i.e. the crystal plane parallel to the fracture plane was nearly of random orientation. - Highlights: • Crystallographic features of a thermo-mechanical fatigue (TMF) crack were studied. • Wide-field 3D EBSD is used to characterize the TMF crack morphology. • Data processing was applied on a large length scale of the order of millimeters. • Graphite density in the fracture plane is much higher than any other random plane. • It is revealed that crack growth is enhanced by the presence of graphite particles.

  17. Integrated Radiation Transport and Thermo-Mechanics Simulation of a PWR Assembly

    SciTech Connect

    Clarno, Kevin T; Hamilton, Steven P; Philip, Bobby; Sampath, Rahul S; Allu, Srikanth; Berrill, Mark A; Barai, Pallab; Banfield, James E

    2012-01-01

    The Advanced Multi-Physics (AMP) Nuclear Fuel Performance code (AMPFuel) is focused on predicting the temperature and strain within a nuclear fuel assembly to evaluate the performance and safety of existing and advanced nuclear fuel bundles within existing and advanced nuclear reactors. AMPFuel was extended to include an integrated nuclear fuel assembly capability for (one-way) coupled radiation transport and nuclear fuel assembly thermo-mechanics. This capability is the initial step towards incorporating an improved predictive nuclear fuel assembly modeling capability to accurately account for source terms, such as the neutron flux distribution, coolant conditions, and assembly mechanical stresses, of traditional (single-pin) nuclear fuel performance simulation. AMPFuel was used to model an entire 17 x 17 Pressurized Water Reactor (PWR) fuel assembly with many of the features resolved in three dimensions (for thermo-mechanics and/or neutronics), including the fuel, gap, and cladding of each of the 264 fuel pins, the 25 guide tubes, top and bottom structural regions, and the upper and lower (neutron) reflector regions. The final full-assembly calculation was executed on Jaguar (Cray XT5) at the Oak Ridge Leadership Computing Facility using 40,000 cores in under 10 hours to model over 162 billion degrees of freedom for 10 loading steps.

  18. Centrifuge Modeling of the Thermo-Mechanical Response of Energy Foundations

    NASA Astrophysics Data System (ADS)

    Goode, Joseph Collin, III

    This thesis presents the results from a series of centrifuge tests performed to understand the profiles of thermo-mechanical axial strain, axial displacement, and axial stress in semi-floating and end-bearing energy foundations installed in dry Nevada sand and Bonny silt layers during different combinations of mechanical loading and foundation heating. In addition to the construction details for the centrifuge scale-model reinforced concrete energy foundations, the results from 1 g thermo-mechanical characterization tests performed on the foundations to evaluate their mechanical and thermal material properties are presented in this thesis. In general, the centrifuge-scale tests involve application of an axial load to the head of the foundation followed by circulation of a heat exchange fluid through embedded tubing to bring the foundation to a constant temperature. After this point, mechanical loads were applied to the foundation to characterize their thermo-mechanical response. Specifically, loading tests to failure were performed on the semi-floating foundation installed in different soil layers to characterize the impact of temperature on the load-settlement curve, and elastic loading tests were performed on the end-bearing foundation to characterize the impact of temperature on the mobilized side shear distributions. During application of mechanical loads and changes in foundation temperature, the axial strains are measured using embedded strain gages. The soil and foundation temperatures, foundation head movement, and soil surface deformations are also monitored to characterize the thermo-mechanical response of the system. The tests performed in this study were used to investigate different phenomena relevant to the thermo-mechanical response of energy foundations. First, the role of end-restraint boundary conditions in both sand and silt were investigated by comparing the strain distributions for the end-bearing and semi-floating foundations in each soil type

  19. Simulation of the PBF-Candu test with coupled thermal-hydraulic and fuel thermo-mechanical responses

    SciTech Connect

    Baschuk, J. J.

    2012-07-01

    During a large loss-of-coolant accident (LLOCA), the fuel sheath temperature is influenced by thermal-hydraulic and thermo-mechanical phenomena. The thermal-hydraulic phenomena include the heat transfer from the sheath to the coolant and surroundings. Thermo-mechanical phenomena, such as creep and thermal expansion, influence the size of the fuel-to-sheath gap, and thus the heat transfer from the fuel to the sheath. Therefore, coupling the thermal-hydraulic and thermo-mechanical analysis of an LLOCA would result in more accurate predictions of sheath temperature. This is illustrated by comparing the sheath temperature predictions from coupled and decoupled simulations of the PBF-Candu Test with experimental measurements. The codes CATHENA and ELOCA were used for the thermal-hydraulic and thermo-mechanical analysis, respectively. The predicted sheath temperatures from both the coupled and decoupled simulations were higher than the measured values. However, after the initial power pulse, when the fuel-to-sheath gap was calculated as being opened, the sheath temperatures predicted by the coupled simulation were closer to the experimental measurements. Thus, under conditions of an open fuel-to-sheath gap, a coupled thermal-hydraulic and thermo-mechanical analysis can improve predictions of sheath temperatures. (authors)

  20. Thermo-mechanical analysis of an internal cooling system with various configurations of a combustion liner after shell

    NASA Astrophysics Data System (ADS)

    Moon, Hokyu; Kim, Kyung Min; Park, Jun Su; Kim, Beom Seok; Cho, Hyung Hee

    2015-12-01

    The after-shell section, which is part of the gas turbine combustion liner, is exposed to the hottest combustion gas. Various cooling schemes have been applied to protect against severe thermal load. However, there is a significant discrepancy in the thermal expansion with large temperature differences, resulting in thermo-mechanical crack formation. In this study, to reduce combustion liner damage, thermo-mechanical analysis was conducted on three after-shell section configurations: inline-discrete divider wall, staggered divider wall, and swirler wall arrays. These array components are well-known heat-transfer enhancement structures in the duct. In the numerical analyses, the heat transfer characteristics, temperature and thermo-mechanical stress distribution were evaluated using finite volume method and finite element method commercial codes. As a result, we demonstrated that the temperature and the thermo-mechanical stress distribution were readily dependent on the structural array for cooling effectiveness and structural support in each modified cooling system. Compared with the reference model, the swirler wall array was most effective in diminishing the thermo-mechanical stress concentration, especially on the inner ring that is vulnerable to crack formation.

  1. Determination of Constitutive Equation for Thermo-mechanical Processing of INCONEL 718 Through Double Multivariate Nonlinear Regression Analysis

    NASA Astrophysics Data System (ADS)

    Hussain, Mirza Zahid; Li, Fuguo; Wang, Jing; Yuan, Zhanwei; Li, Pan; Wu, Tao

    2015-07-01

    The present study comprises the determination of constitutive relationship for thermo-mechanical processing of INCONEL 718 through double multivariate nonlinear regression, a newly developed approach which not only considers the effect of strain, strain rate, and temperature on flow stress but also explains the interaction effect of these thermo-mechanical parameters on flow behavior of the alloy. Hot isothermal compression experiments were performed on Gleeble-3500 thermo-mechanical testing machine in the temperature range of 1153 to 1333 K within the strain rate range of 0.001 to 10 s-1. The deformation behavior of INCONEL 718 is analyzed and summarized by establishing the high temperature deformation constitutive equation. The calculated correlation coefficient ( R) and average absolute relative error ( AARE) underline the precision of proposed constitutive model.

  2. Influence of Carbon Nano Tubes on the Thermo-Mechanical Properties of Unsaturated Polyester Nanocomposite

    NASA Astrophysics Data System (ADS)

    Moshiul Alam, A. K. M.; Beg, M. D. H.; Mohd Yunus, Rosli

    2015-04-01

    To date nano fillers are renowned reinforcing agent for polymer materials. In this work, unsaturated polyester (UPR) nanocomposites were fabricated by 0.1, 0.3 and 0.5 wt% multi walled carbon nanotubes (MWCNTs) through solution dispersion and casting method. The influence of MWCNT content was investigated by thermo-mechanical properties. Dispersion of nanotubes was observed by fracture morphology. The strength of nanocomposites rose with raising the CNT content. Moreover, DSC thermograms of nanocomposites represent noticeable improvement of glass transition temperature (Tg), melting temperature (Tm) and enthalpy (ΔHm). Micro-crystallinity of nanocomposites increased with increasing the CNT content. Moreover, the stiffness increased with increasing the CNT content.

  3. Grain boundary character modification employing thermo-mechanical processing in type 304L stainless steel

    NASA Astrophysics Data System (ADS)

    Pradhan, S. K.; Mandal, S.

    2016-02-01

    Grain boundary engineering (GBE) approach has been employed to modify the boundaries character of a type 304L stainless steel through thermo-mechanical processing (TMP) route, which combined a low level of cold deformation (5, 10 and 15%) followed by annealing at 1173K and 1273K for 1hour. Employing Electron Back Scatter Diffraction based Orientation Imaging Microscopy, the fraction and distribution of low ∑ CSL boundaries (∑≤ 29) and its effect on random high-angle grain boundaries connectivity and triple junction distribution of as-received (AR) and GBE specimens were evaluated. It was possible to increase the fraction of low ∑ CSL boundaries up to 75% following GBE treatment (as compared to 50% in AR specimen). The GBE specimens also contained maximum number of percolation resistant triple junctions which could render better resistance against percolation related phenomena.

  4. Decomposition and Precipitation Process During Thermo-mechanical Fatigue of Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Weidner, Anja; Kolmorgen, Roman; Kubena, Ivo; Kulawinski, Dirk; Kruml, Tomas; Biermann, Horst

    2016-05-01

    The so-called 748 K (475 °C) embrittlement is one of the main drawbacks for the application of ferritic-austenitic duplex stainless steels (DSS) at higher temperatures caused by a spinodal decomposition of the ferritic phase. Thermo-mechanical fatigue tests performed on a DSS in the temperature range between 623 K and 873 K (350 °C and 600 °C) revealed no negative influence on the fatigue lifetime. However, an intensive subgrain formation occurred in the ferritic phase, which was accompanied by formation of fine precipitates. In order to study the decomposition process of the ferritic grains due to TMF testing, detailed investigations using scanning and transmission electron microscopy are presented. The nature of the precipitates was determined as the cubic face centered G-phase, which is characterized by an enrichment of Si, Mo, and Ni. Furthermore, the formation of secondary austenite within ferritic grains was observed.

  5. Evaluation of Thermal and Thermo-mechanical Behavior of Full-scale Energy Foundations

    NASA Astrophysics Data System (ADS)

    Murphy, Kyle D.

    This study focuses on the thermo-mechanical and thermal behavior of full-scale energy foundations installed as part of two buildings recently constructed in Colorado. The soil stratigraphy at each of the sites differed, but both foundations were expected to function as primarily end-bearing elements with a tip socketed into rock. The heat exchanger configurations were also different amongst the foundations at both sites, permitting evaluation of the role of heat exchange. A common thread for both energy foundation case histories was the monitoring of the temperature and axial strain within the foundations during heat exchange operations. The first case study involves an evaluation of the long-term thermo-mechanical response of two full-scale energy foundations installed at the new Denver Housing Authority (DHA) Senior Living Facility at 1099 Osage St. in Denver, Colorado. Due to the construction schedule for this project, the thermal properties of the foundations and surrounding subsurface could not be assessed using thermal response tests. However, instrumentation was incorporated into the foundations to assess their long-term heat exchange response as well as the thermo-mechanical strains, stresses, and displacements that occurred during construction and operation of the ground-source heat pump system. The temperature changes within the foundations during heating and cooling operations over a period of approximately 600 days ranged from 9 to 32 °C, respectively. The thermal axial stresses in the foundations were calculated from the measured strains, and ranged from 3.1 MPa during heating to --1.0 MPa during cooling. These values are within reasonable limits for reinforced concrete structures. The maximum thermal axial stress was observed near the toe of both foundations, which is consistent with trends expected for end-bearing toe boundary conditions. The greatest thermal axial strains were observed near the top of the foundations (upward expansion during

  6. Modeling of the thermo-mechanical efficiency of the bimetal strip heat engines

    NASA Astrophysics Data System (ADS)

    Arnaud, A.; Monfray, S.; Boughaleb, J.; Trioux, E.; Boeuf, F.; Cugat, O.; Skotnicki, T.

    2014-11-01

    This paper presents a theoretical demonstration of the bimetal strip heat engine working, based on the study of the thermo-mechanical instability of the pre-buckled bimetallic beams. Starting from the Euler buckling equation, this paper describes the bimetal strips like classical but non-linear thermodynamic systems, and gives the bistability criterion of such beams. Studying the thermodynamic potentials of these beams helps to evaluate the release of the kinetic energy happening during the beam snap-through, to give the Maxwell relations between each partial derivative of the thermodynamic potentials and to show that the thermal snap-through is a first-order transition according to the Ehrenfest theory. The model is then used to draw the temperature-entropy cycle of the bimetal heat engines and to evaluate the performances of these harvesters (available mechanical energy and thermodynamic cycle efficiency).

  7. Thermo-mechanical characterization of insulated and epoxy-impregnated Nb3Sn composites

    SciTech Connect

    Linda Imbasciati et al.

    2002-12-11

    Nb{sub 3}Sn is, at present, the best superconductor for high field accelerator magnets. Several models using Nb{sub 3}Sn are under development in many laboratories. Knowledge of the thermo-mechanical properties of the impregnated coils is of crucial importance for the design of these magnets. In fact, the performance of epoxy-impregnated coils is sensitive to the thermal conductivity value, especially in case of heating caused by hysteretic losses, which are usually relevant in Nb{sub 3}Sn magnets, and in the case of continuous heat deposition, such as in magnets near the interaction region of a collider. Thermal contraction measurements are necessary to estimate the stresses during the magnet thermal cycle. Different insulation materials have been studied at Fermilab utilizing various design approaches and fabrication methods. Thermal conductivity and thermal contraction measurements, at cryogenic temperatures, have been performed respectively at INFN-LASA and Fermilab. The results are reported and discussed in this paper.

  8. A thermo-mechanically coupled finite strain model considering inelastic heat generation

    NASA Astrophysics Data System (ADS)

    Dunić, Vladimir; Busarac, Nenad; Slavković, Vukašin; Rosić, Bojana; Niekamp, Rainer; Matthies, Hermann; Slavković, Radovan; Živković, Miroslav

    2016-07-01

    The procedure for reuse of finite element method (FEM) programs for heat transfer and structure analysis to solve advanced thermo-mechanical problems is presented as powerful algorithm applicable for coupling of other physical fields (magnetic, fluid flow, etc.). In this case, nonlinear Block-Gauss-Seidel partitioned algorithm strongly couples the heat transfer and structural FEM programs by a component-based software engineering. Component template library provides possibility to exchange the data between the components which solve the corresponding subproblems. The structural component evaluates the dissipative energy induced by inelastic strain. The heat transfer component computes the temperature change due to the dissipation. The convergence is guaranteed by posing the global convergence criterion on the previously locally converged coupled variables. This enables reuse of software and allows the numerical simulation of thermo-sensitive problems.

  9. Thermo-mechanical analyses of HELICA and HEXCALIBER mock-ups

    NASA Astrophysics Data System (ADS)

    Gan, Yixiang; Kamlah, Marc

    2009-04-01

    As benchmark exercises, HELICA and HEXCALIBER mock-ups have been launched in the HE-FUS 3 facility at ENEA Brasimone for investigating the thermo-mechanical behaviour of pebble beds. The present material model of pebble beds, based on the modified Drucker-Prager-Cap model, has been implemented in the commercial finite element package, ABAQUS. The overall behaviour of the lithium orthosilicate cassette (HELICA) and the interactions of ceramic breeder pebble beds and beryllium pebble beds (HEXCALIBER) are studied numerically. The finite element analyses show the temperature distribution of the mock-up experiments, as well as the stress-strain fields. The predictions of HELICA mock-up are compared with the experiments, including the temperature measured by thermo-couples located inside the pebble beds and the lateral deformation of the cell.

  10. An Approximate Dissipation Function for Large Strain Rubber Thermo-Mechanical Analyses

    NASA Technical Reports Server (NTRS)

    Johnson, Arthur R.; Chen, Tzi-Kang

    2003-01-01

    Mechanically induced viscoelastic dissipation is difficult to compute. When the constitutive model is defined by history integrals, the formula for dissipation is a double convolution integral. Since double convolution integrals are difficult to approximate, coupled thermo-mechanical analyses of highly viscous rubber-like materials cannot be made with most commercial finite element software. In this study, we present a method to approximate the dissipation for history integral constitutive models that represent Maxwell-like materials without approximating the double convolution integral. The method requires that the total stress can be separated into elastic and viscous components, and that the relaxation form of the constitutive law is defined with a Prony series. Numerical data is provided to demonstrate the limitations of this approximate method for determining dissipation. Rubber cylinders with imbedded steel disks and with an imbedded steel ball are dynamically loaded, and the nonuniform heating within the cylinders is computed.

  11. Development of Semantic Description for Multiscale Models of Thermo-Mechanical Treatment of Metal Alloys

    NASA Astrophysics Data System (ADS)

    Macioł, Piotr; Regulski, Krzysztof

    2016-06-01

    We present a process of semantic meta-model development for data management in an adaptable multiscale modeling framework. The main problems in ontology design are discussed, and a solution achieved as a result of the research is presented. The main concepts concerning the application and data management background for multiscale modeling were derived from the AM3 approach—object-oriented Agile multiscale modeling methodology. The ontological description of multiscale models enables validation of semantic correctness of data interchange between submodels. We also present a possibility of using the ontological model as a supervisor in conjunction with a multiscale model controller and a knowledge base system. Multiscale modeling formal ontology (MMFO), designed for describing multiscale models' data and structures, is presented. A need for applying meta-ontology in the MMFO development process is discussed. Examples of MMFO application in describing thermo-mechanical treatment of metal alloys are discussed. Present and future applications of MMFO are described.

  12. Third-order thermo-mechanical properties for packs of Platonic solids using statistical micromechanics

    PubMed Central

    Gillman, A.; Amadio, G.; Matouš, K.; Jackson, T. L.

    2015-01-01

    Obtaining an accurate higher order statistical description of heterogeneous materials and using this information to predict effective material behaviour with high fidelity has remained an outstanding problem for many years. In a recent letter, Gillman & Matouš (2014 Phys. Lett. A 378, 3070–3073. ()) accurately evaluated the three-point microstructural parameter that arises in third-order theories and predicted with high accuracy the effective thermal conductivity of highly packed material systems. Expanding this work here, we predict for the first time effective thermo-mechanical properties of granular Platonic solid packs using third-order statistical micromechanics. Systems of impenetrable and penetrable spheres are considered to verify adaptive methods for computing n-point probability functions directly from three-dimensional microstructures, and excellent agreement is shown with simulation. Moreover, a significant shape effect is discovered for the effective thermal conductivity of highly packed composites, whereas a moderate shape effect is exhibited for the elastic constants. PMID:27547103

  13. Thermo-mechanical analysis of LWR SiC/SiC composite cladding

    NASA Astrophysics Data System (ADS)

    Ben-Belgacem, M.; Richet, V.; Terrani, K. A.; Katoh, Y.; Snead, L. L.

    2014-04-01

    A dedicated framework for thermo-mechanical analysis of the in-pile performance of SiC/SiC composite fuel cladding concepts in LWRs has been developed. This analysis framework focuses on cladding and omits any fuel-cladding interaction and fuel behavior. Since radial expansion of the cladding occurs early in life for these ceramic structures, fuel-cladding contact is expected to be delayed or eliminated and therefore it is not considered in this analysis. The analysis inputs recent out-of-pile and in-pile materials property data and phenomenological understanding of material evolution under neutron irradiation for nuclear-grade SiC/SiC composites to provide a best-estimate analysis. The analysis provides insight into the concept design and feasibility of SiC/SiC composite cladding concepts that exhibit significantly different behavior than metallic cladding structures. In particular, absence of any tangible creep (thermal or irradiation) coupled with a large and temperature-gradient-driven irradiation swelling strain gradient across the cladding, drive development of large stresses across the cladding thickness. The resulting analysis indicates that significant stresses develop after a modest neutron dose (∼1 dpa) and a pronounced variation across the cladding thickness exists and is opposite to that observed for metallic cladding structures where swelling or growth strains are either negligible (with small temperature dependence) or absent. Following this thermo-mechanical analysis, a best-estimate and parametric examination of SiC/SiC fuel rod cladding structures has been performed using appropriate Weibull statistics to prescribe basic design guidelines and to begin to define a probable design space.

  14. Thermo-mechanical modeling of the electrically-assisted manufacturing (EAM) technique during open die forging

    NASA Astrophysics Data System (ADS)

    Salandro, Wesley A.

    This thesis contains all of the steps which allow the Electrically-Assisted Manufacturing (EAM) technique to be experimentally explored and analytically modeled for an electrically-assisted forging operation. Chapter 1 includes the problem statement, proposed solution, and literature reviews on EAM. Chapter 2 describes a thorough background on the EAM technique, highlights prior EAM research, and explains the research approach taken for this thesis. The coupled thermo-mechanical modeling strategy, along with the introduction of the Electroplastic Effect Coefficient (EEC) is provided in Chapter 3. Chapter 4 explains the two different approaches to determine the EEC profiles when modeling a particular metal. The simplified EAF mechanical model for electrically-assisted forging is presented in Chapter 5. Also in this chapter, the same modeling methodology (i.e. thermo-mechanical, EEC, etc.) is used to predict loads for an electrically-assisted bending (EAB) process. The following chapters explore how different material- and process-based parameters affect the EAF technique. Chapter 6 examines how different workpiece contact areas affect EAF effectiveness, along with an exploration of how well different metal forming lubricants perform with EAF. Chapter 7 explores if there is a difference in the thermal or mechanical profiles of specimens undergoing EAF forging tests with different average grain sizes. Chapter 8 examines the same effects as the previous chapter on specimens with varying levels of prior cold work. The materials- and process-based simplifications and sensitivities of the proposed modeling strategy are outlined in Chapter 9. Chapters 10-14 include the science behind the electroplastic effect, conclusions, future work, broader impacts, and intellectual merit, respectively. The overall intention of this thesis is to show the candidate's ability to take an idea for a new manufacturing process, prove that it works, and then understand and model the process

  15. Thermo-mechanical modelling of salt caverns due to fluctuating loading conditions.

    NASA Astrophysics Data System (ADS)

    Böttcher, N.

    2015-12-01

    This work summarizes the development and application of a numerical model for the thermo-mechanical behaviour of salt caverns during cyclic gas storage. Artificial salt caverns are used for short term energy storage, such as power-to-gas or compressed air energy storage. Those applications are characterized by highly fluctuating operation pressures due to the unsteady power levels of power plants based on renewable energy. Compression and expansion of the storage gases during loading and unloading stages lead to rapidly changing temperatures in the host rock of the caverns. This affects the material behaviour of the host rock within a zone that extends several meters into the rock mass adjacent to the cavern wall, and induces thermo-mechanical stresses and alters the creep response.The proposed model features the thermodynamic behaviour of the storage medium, conductive heat transport in the host rock, as well as temperature dependent material properties of rock salt using different thermo-viscoplastic material models. The utilized constitutive models are well known and state-of-the-art in various salt mechanics applications. The model has been implemented into the open-source software platform OpenGeoSys. Thermal and mechanical processes are solved using a finite element approach, coupled via a staggered coupling scheme. The simulation results allow the conclusion, that the cavern convergence rate (and thus the efficiency of the cavern) is highly influenced by the loading cycle frequency and the resulting gas temperatures. The model therefore allows to analyse the influence of operation modes on the cavern host rock or on neighbouring facilities.

  16. Thermo-mechanical processing of austenitic steel to mitigate surface related degradation

    NASA Astrophysics Data System (ADS)

    Idell, Yaakov Jonathan

    Thermo-mechanical processing plays an important role in materials property optimization through microstructure modification, required by demanding modern materials applications. Due to the critical role of austenitic stainless steels, such as 316L, as structural components in harsh environments, e.g. in nuclear power plants, improved degradation resistance is desirable. A novel two-dimensional plane strain machining process has shown promise achieving significant grain size refinement through severe plastic deformation (SPD) and imparting large strains in the surface and subsurface regions of the substrate in various metals and alloys. The deformation process creates a heavily deformed 20 -- 30 micron thick nanocrystalline surface layer with increased hardness and minimal martensite formation. Post-deformation processing annealing treatments have been applied to assess stability of the refined scale microstructures and the potential for obtaining grain boundary engineered microstructures with increased fraction of low-energy grain boundaries and altered grain boundary network structure. Varying the deformation and heat treatment process parameters, allows for development of a full understanding of the nanocrystalline layer and cross-section of the surface substrate created. Micro-characterization was performed using hardness measurements, magnetometry, x-ray diffraction, scanning and transmission electron microscopy to assess property and microstructural changes. This study provides a fundamental understanding of two-dimensional plane strain machining as a thermo-mechanical processing technique, which may in the future deliver capabilities for creating grain boundary engineered surface modified components, typified by a combination of grain refinement with improved grain boundary network interconnectivity attributes suitable for use in harsh environments, such as those in commercial nuclear power plants where improved resistance to irradiation stress corrosion

  17. Enhancement of the electrochemical behaviour and biological performance of Ti-25Ta-5Zr alloy by thermo-mechanical processing.

    PubMed

    Cimpean, Anisoara; Vasilescu, Ecaterina; Drob, Paula; Cinca, Ion; Vasilescu, Cora; Anastasescu, Mihai; Mitran, Valentina; Drob, Silviu Iulian

    2014-05-01

    A new Ti-25Ta-5Zr alloy based only on non-toxic and non-allergic elements was elaborated in as-cast and thermo-mechanical processed, recrystallized states (XRD and SEM) in order to be used as candidate material for implant applications. Its long-term interactions with Ringer-Brown and Ringer solutions of different pH values and its cytocompatibility were determined. The thermo-mechanically processed alloy has nobler electrochemical behaviour than as-cast alloy due to finer microstructure obtained after the applied treatment. Corrosion and ion release rates presented the lowest values for the treated alloy. Nyquist and Bode plots displayed higher impedance values and phase angles for the processed alloy, denoting a more protective passive film. SEM micrographs revealed depositions from solutions that contain calcium, phosphorous and oxygen ions (EDX analysis), namely calcium phosphate. An electric equivalent circuit with two time constants was modelled. Cell culture experiments with MC3T3-E1 pre-osteoblasts demonstrated that thermo-mechanically processed Ti-25Ta-5Zr alloy supports a better cell adhesion and spreading, and enhanced cell proliferation. Altogether, these data indicate that thermo-mechanical treatment endows the alloy with improved anticorrosion and biological performances. PMID:24656361

  18. Second-order two-scale finite element algorithm for dynamic thermo-mechanical coupling problem in symmetric structure

    NASA Astrophysics Data System (ADS)

    Li, Zhi-Hui; Ma, Qiang; Cui, Junzhi

    2016-06-01

    The new second-order two-scale (SOTS) finite element algorithm is developed for the dynamic thermo-mechanical coupling problems in axisymmetric and spherical symmetric structures made of composite materials. The axisymmetric structure considered is periodic in both radial and axial directions and homogeneous in circumferential direction. The spherical symmetric structure is only periodic in radial direction. The dynamic thermo-mechanical coupling model is presented and the equivalent compact form is derived. Then, the cell problems, effective material coefficients and the homogenized thermo-mechanical coupling problem are obtained successively by the second-order asymptotic expansion of the temperature increment and displacement. The homogenized material obtained is manifested with the anisotropic property in the circumferential direction. The explicit expressions of the homogenized coefficients in the plane axisymmetric and spherical symmetric cases are given and both the derivation of the analytical solutions of the cell functions and the quasi-static thermoelasticity problems are discussed. Based on the SOTS method, the corresponding finite-element procedure is presented and the unconditionally stable implicit algorithm is established. Some numerical examples are solved and the mutual interaction between the temperature and displacement field is studied under the condition of structural vibration. The computational results demonstrate that the second-order asymptotic analysis finite-element algorithm is feasible and effective in simulating and predicting the dynamic thermo-mechanical behaviors of the composite materials with small periodic configurations in axisymmetric and spherical symmetric structures. This may provide a vital computational tool for analyzing composite material internal temperature distribution and structural deformation induced by the dynamic thermo-mechanical coupling response under strong aerothermodynamic environment.

  19. Experiments on melt ascent by thermo-mechanical erosion in a magma chamber

    NASA Astrophysics Data System (ADS)

    Shibano, Y.; Sumita, I.; Namiki, A.

    2011-12-01

    A intruding hot magma can melt the colder host rock and ascend. Huppert and Sparks (1988) experimentally modeled this process of thermal erosion by using a hot aqueous solution for the magma and wax as the overlying host rock. When the host rock becomes partially molten, crystals with high melting temperature (e.g., olivine) should settle downwards and affect the thermal convection within the magma. However, this mechanical process was not considered in the previous works. Here we model this process of thermo-mechanical erosion and resulting melt ascent, and conduct a series of experiments in which a convecting molten wax(PEG1000) melts the overlying solid wax which contains glass bead particles (i.e., crystals). We use a quasi-two-dimensional cell (8±8±1cm) and set a vertical temperature difference of Δ T = 33oC. When the solid wax melts, the glass beads settle downwards and affect the convection. Here, the primary control parameter is the glass beads size (d). For d > 180 μ m, the particle settling occurs continuously and are not suspended within the liquid layer. However, for d < 180 μ m, we find that the particle settling occurs in a cyclic manner. Here the particles are being suspended within the liquid layer which suppresses the convection and hence the upward heat transfer. As a consequence, melting of the solid layer ceases after a certain time elapses. When the temperature within the liquid layer becomes sufficiently high, cold plumes develop from the roof and melting and particle settling resumes. We classify the results using three velocities; Vs = Stokes velocity, Vm = roof melting velocity and Vc = convection velocity. We find that when Vm ˜ Vs < Vc, the particles are being suspended in the liquid layer and melting occurs in a cyclic manner. On the other hand, when Vm < Vs < Vc, particle settling occurs continuously. For Vm < Vc ˜ Vs, we find that the thermal convection has a negligible effect on particle settling. We may apply the criterion for

  20. Magmatism vs mushmatism: 2D thermo-mechanical modelling of crustal mush processes

    NASA Astrophysics Data System (ADS)

    Roele, K.; Morgan, J. V.; Jackson, M.

    2015-12-01

    The concept of 'mushmatism'- that a magma chamber resides in a crystalline state for the majority of its life, has been suggested as a plausible mechanism for observed crustal melt evolution. It is proposed that as melt is generated, its composition evolves as it rises buoyantly, reacting chemically with the surrounding crystal mush at progressively lower temperatures. It is therefore possible to explain formation of granitic melts and observed mafic-felsic layering in the crust using mush processes. It has previously been assumed that a high influx rate of molten material is required for large volumes of crustal melt to be produced. This has been modelled in the past with repetitive sill intrusion at unrealistically high rates (>3x107 m3a-1) to cause a large enough thermal perturbation of the geotherm to sustain eruptible melt in the shallow crust. However, these models are purely thermal and neglect the effects of melt segregation and mush processes on longevity of melt volumes in the crust. We have developed an axisymmetric thermo-mechanical model that includes mass transport described by coupled matrix compaction and buoyant melt segregation during repeated sill intrusion. Results are consistent with thermal models in that they demonstrate dominance of crystalline mush processes in the transient magma chamber at low-to-moderate intrusion rates. However, addition of buoyant segregation leads to formation of discrete high melt fraction layers as melt ascends through the emplacement zone. This causes a decoupling in location of maximum temperature and melt fraction not observed by purely thermal models. Our results therefore have significant implications for current methods of interpretation of geophysical data, in particular, calculating melt volumes and determining the depth of the magma chamber. In addition, transient reservoirs are produced at lower emplacement rates by the thermo-mechanical model because accumulated magma is evolved and able to remain liquid

  1. Dynamic Thermo-Mechanical Phase-Field Models for Martensitic Transformations in Shape Memory Alloys

    NASA Astrophysics Data System (ADS)

    Dhote, Rakesh

    Shape memory alloys (SMAs) exhibit complex microstructures and non-linear hysteretic behaviors that arise from a strong interaction between mechanical and thermal phenomena. It is imperative to couple the thermal physics and the mechanical dynamics to study the influence of such coupling on the mechanical properties of SMA systems, including nanostructures. However, the majority of phase-field models in the literature related to SMAs account for structural physics only. With the aim to incorporate thermal physics, in this thesis, first the 2D and 3D dynamic fully coupled thermo-mechanical phase-field models are developed based on the strain-based order parameters. The developed models are highly nonlinear, strongly hysteretic with fourth-order spatial differential terms, which impose several computational challenges. Secondly, to overcome these computational challenges, a numerical formulation based on the isogeometric analysis is developed for a straightforward solution to the fourth-order differential equations using continuously differentiable non-uniform rational B-splines (NURBS). Several numerical examples of microstructure evolution in SMA systems, in particular nanostructures of different geometries, under temperature and stress induced loadings illustrated the flexibility, accuracy and robustness of the developed numerical formulation. The numerical simulations revealed a significant impact of the temperature dynamics on mechanical properties of SMAs. The developed models successfully captured experimentally observed mechanical and thermal hysteresis phenomena, local non-uniform phase transformations and corresponding non-uniform temperature and deformations distributions. The predicted microstructure evolution is in qualitative agreement with the results reported in the literature. The material properties of austenite and martensite phases are different, as observed experimentally during phase transformations. However, the majority of macroscale non

  2. Environmental and Thermo-Mechanical Stability of Thin Films for Optical Applications

    NASA Astrophysics Data System (ADS)

    Mao, Yalan

    1990-01-01

    We have selected two materials to study the stability of thin-films: (1) TbFe, a candidate material for optical data storage, for environmental stability study; (2) ZrO _2, a dielectric material for optical coatings, for thermo-mechanical stability study. In the research on TbFe sputtered films, we applied surface plasma resonance as a vehicle to study the optical constants of a single layer TbFe film and to study the instability of a multilayer system of TbFe, with protective layer Al_2O_3 and coupling layer MgF_2 (structure: glass/MgF_2/TbFe/Al_2 O_3/air), as a function of time. The results show that with our multilayer system there was only slight environmental instability during the first day and the system stabilized there after. However the TbFe film did exhibit some oxidation on exposure to 200^circC for two hours. Water, which may penetrate into the MgF_2 layer from the side may accelerate the oxidation. It is therefore necessary to have side protection and to avoid long period exposure to high temperature. In the research on ZrO_2 evaporated films, with and without ion-assisted deposition (IAD), we performed interferometry in a vacuum oven to study total stress of films as a function of temperature. On thermal cycling, all the plots of stress versus temperature for IAD and non-IAD films exhibit hysteresis. In order to understand the hysteresis, we studied microstructure and water effects. The results show that the likely mechanisms are water desorption, recrystallization and phase transformation and we believe that a combination of all three occurred. Our results also show that ion assisted deposition (increasing deposition temperature tends to give more tensile stress) and high deposition temperature (increasing deposition temperature tends to give less tensile stress) gave more stable films both thermo-mechanically and optically. It is well known that the thermal stress is due to thermal expansion coefficient mismatch between substrate and film. But if

  3. Grain boundary engineering in a thermo-mechanically processed Nb-stabilized austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Yunquera, A.; Jorge-Badiola, D.; Gutiérrez, I.; Iza-Mendia, A.

    2015-04-01

    Three different thermo-mechanical strategies—annealing, strain recrystallization and strain annealing—were applied to a Nb-stabilized 304H austenitic stainless steel in order to study their effects on grain boundary character distribution (GBCD). An Electron Backscatter Diffraction (EBSD) analysis revealed specific combinations of cold reduction-temperature-time that favor annealing twinning. A uniform increase in microstructural size and special boundaries (particularly for Σ3, Σ9 and Σ27 boundaries) was achieved under strain annealing conditions (low cold reductions) and long times at high temperatures (≥ 990°C). These conditions provide a high fraction of special boundaries (about 80%), which replace the random grain boundary network and thus optimize the GBCD. The profuse presence of Σ3n boundaries is attributed to the geometric interaction of twin-related variants during grain boundary migration. In addition to all this, precipitation takes place at the temperature range where optimum GBCD is achieved. The significance of precipitation in the different strategies was also tackled.

  4. Space Shuttle Orbiter Wing-Leading-Edge Panel Thermo-Mechanical Analysis for Entry Conditions

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Song, Kyongchan; Raju, Ivatury S.

    2010-01-01

    Linear elastic, thermo-mechanical stress analyses of the Space Shuttle Orbiter wing-leading-edge panels is presented for entry heating conditions. The wing-leading-edge panels are made from reinforced carbon-carbon and serve as a part of the overall thermal protection system. Three-dimensional finite element models are described for three configurations: integrated configuration, an independent single-panel configuration, and a local lower-apex joggle segment. Entry temperature conditions are imposed and the through-the-thickness response is examined. From the integrated model, it was concluded that individual panels can be analyzed independently since minimal interaction between adjacent components occurred. From the independent single-panel model, it was concluded that increased through-the-thickness stress levels developed all along the chord of a panel s slip-side joggle region, and hence isolated local joggle sections will exhibit the same trend. From the local joggle models, it was concluded that two-dimensional plane-strain models can be used to study the influence of subsurface defects along the slip-side joggle region of these panels.

  5. Probabilistic Simulation of Combined Thermo-Mechanical Cyclic Fatigue in Composites

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    2011-01-01

    A methodology to compute probabilistically-combined thermo-mechanical fatigue life of polymer matrix laminated composites has been developed and is demonstrated. Matrix degradation effects caused by long-term environmental exposure and mechanical/thermal cyclic loads are accounted for in the simulation process. A unified time-temperature-stress-dependent multifactor-interaction relationship developed at NASA Glenn Research Center has been used to model the degradation/aging of material properties due to cyclic loads. The fast probability-integration method is used to compute probabilistic distribution of response. Sensitivities of fatigue life reliability to uncertainties in the primitive random variables (e.g., constituent properties, fiber volume ratio, void volume ratio, ply thickness, etc.) computed and their significance in the reliability-based design for maximum life is discussed. The effect of variation in the thermal cyclic loads on the fatigue reliability for a (0/+/-45/90)s graphite/epoxy laminate with a ply thickness of 0.127 mm, with respect to impending failure modes has been studied. The results show that, at low mechanical-cyclic loads and low thermal-cyclic amplitudes, fatigue life for 0.999 reliability is most sensitive to matrix compressive strength, matrix modulus, thermal expansion coefficient, and ply thickness. Whereas at high mechanical-cyclic loads and high thermal-cyclic amplitudes, fatigue life at 0.999 reliability is more sensitive to the shear strength of matrix, longitudinal fiber modulus, matrix modulus, and ply thickness.

  6. Probabilistic Simulation of Combined Thermo-Mechanical Cyclic Fatigue in Composites

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    2010-01-01

    A methodology to compute probabilistically-combined thermo-mechanical fatigue life of polymer matrix laminated composites has been developed and is demonstrated. Matrix degradation effects caused by long-term environmental exposure and mechanical/thermal cyclic loads are accounted for in the simulation process. A unified time-temperature-stress-dependent multifactor-interaction relationship developed at NASA Glenn Research Center has been used to model the degradation/aging of material properties due to cyclic loads. The fast probability-integration method is used to compute probabilistic distribution of response. Sensitivities of fatigue life reliability to uncertainties in the primitive random variables (e.g., constituent properties, fiber volume ratio, void volume ratio, ply thickness, etc.) computed and their significance in the reliability-based design for maximum life is discussed. The effect of variation in the thermal cyclic loads on the fatigue reliability for a (0/+/-45/90)s graphite/epoxy laminate with a ply thickness of 0.127 mm, with respect to impending failure modes has been studied. The results show that, at low mechanical-cyclic loads and low thermal-cyclic amplitudes, fatigue life for 0.999 reliability is most sensitive to matrix compressive strength, matrix modulus, thermal expansion coefficient, and ply thickness. Whereas at high mechanical-cyclic loads and high thermal-cyclic amplitudes, fatigue life at 0.999 reliability is more sensitive to the shear strength of matrix, longitudinal fiber modulus, matrix modulus, and ply thickness.

  7. A numerical model of hydro-thermo-mechanical coupling in a fractured rock mass

    SciTech Connect

    Bower, K.M.

    1996-06-01

    Coupled hydro-thermo-mechanical codes with the ability to model fractured materials are used for predicting groundwater flow behavior in fractured aquifers containing thermal sources. The potential applications of such a code include the analysis of groundwater behavior within a geothermal reservoir. The capability of modeling hydro-thermo systems with a dual porosity, fracture flow model has been previously developed in the finite element code, FEHM. FEHM has been modified to include stress coupling with the dual porosity feature. FEHM has been further developed to implicitly couple the dependence of fracture hydraulic conductivity on effective stress within two dimensional, saturated aquifers containing fracture systems. The cubic law for flow between parallel plates was used to model fracture permeability. The Bartin-Bandis relationship was used to determine the fracture aperture within the cubic law. The code used a Newton Raphson iteration to implicitly solve for six unknowns at each node. Results from a model of heat flow from a reservoir to the moving fluid in a single fracture compared well with analytic results. Results of a model showing the increase in fracture flow due to a single fracture opening under fluid pressure compared well with analytic results. A hot dry rock, geothermal reservoir was modeled with realistic time steps indicating that the modified FEHM code does successfully model coupled flow problems with no convergence problems.

  8. Time Evolution of Thermo-Mechanically and Chemically Coupled Magma Chambers

    NASA Astrophysics Data System (ADS)

    Ozimek, C.; Karlstrom, L.; Erickson, B. A.

    2015-12-01

    Complexity in the volcanic eruption cycle reflects time variation both of magma inputs to the crustal plumbing system and of crustal melt storage zones (magma chambers). These data include timing and volumes of eruptions, as well as erupted compositions. Thus models must take into account the coupled nature of physical attributes. Here we combine a thermo-mechanical model for magma chamber growth and pressurization with a chemical model for evolving chamber compositions, in the limit of rapid mixing, to study controls on eruption cycles and compositions through time. We solve for the mechanical evolution of a 1D magma chamber containing melt, crystals and bubbles, in a thermally evolving and viscoelastic crust. This pressure and temperature evolution constrains the input values of a chemical box model (Lee et al., 2013) that accounts for recharge, eruption, assimilation and fractional crystallization (REAFC) within the chamber. We plan to study the influence of melt supply, input composition, and chamber depth eruptive fluxes and compositions. Ultimately we will explore multiple chambers coupled by elastic-walled dikes. We expect that this framework will facilitate self-consistent inversion of long-term eruptive histories in terms of magma transport physics. Lee, C.-T. A., Lee, T.-C., Wu, C.-T., 2013. Modeling the compositional evolution of recharging, evacuating, and fractionating (REFC) magma chambers: Implications for differentiationof arc magmas. Geochemica Cosmochimica Acta, http://dx.doi.org/10.1016/j.gca.2013.08.009.

  9. Closed-form analysis of fiber-matrix interface stresses under thermo-mechanical loadings

    NASA Technical Reports Server (NTRS)

    Naik, Rajiv A.; Crews, John H., Jr.

    1992-01-01

    Closed form techniques for calculating fiber matrix (FM) interface stresses, using repeating square and diamond regular arrays, were presented for a unidirectional composite under thermo-mechanical loadings. An Airy's stress function micromechanics approach from the literature, developed for calculating overall composite moduli, was extended in the present study to compute FM interface stresses for a unidirectional graphite/epoxy (AS4/3501-6) composite under thermal, longitudinal, transverse, transverse shear, and longitudinal shear loadings. Comparison with finite element results indicate excellent agreement of the FM interface stresses for the square array. Under thermal and longitudinal loading, the square array has the same FM peak stresses as the diamond array. The square array predicted higher stress concentrations under transverse normal and longitudinal shear loadings than the diamond array. Under transverse shear loading, the square array had a higher stress concentration while the diamond array had a higher radial stress concentration. Stress concentration factors under transverse shear and longitudinal shear loadings were very sensitive to fiber volume fraction. The present analysis provides a simple way to calculate accurate FM interface stresses for both the square and diamond array configurations.

  10. Effect of electro-thermo-mechanical coupling on the short-circuit in RF microswitch operation

    NASA Astrophysics Data System (ADS)

    Brusa, E.; Munteanu, M. G.

    2011-06-01

    A phenomenological approach is herein followed to describe several superimposed effects occurring within the structure of microswitch for radio frequency application (RF-MEMS). This device is operated via a nonlinear electromechanical action imposed by applied voltage. Unfortunately, it is usually affected by residual stress, after microfabrication, therefore axial and flexural behaviors are coupled. This coupling increases actuation voltage to achieve the so-called "pull-in" condition. Moreover, temperature may strongly affect strain and stress distributions, respectively. Environmental temperature, internal dissipation of material, thermo-elastic and Joule effects play different roles on the microswitch flexural displacement. Sometimes buckling phenomenon evenly occurs. Finally, if stress concentration on microbeam cross section is sufficiently large, plastic behavior may arise. All those aspects make difficult an effective computation of pull-in voltage, understanding actual behavior of microsystem, particularly when several loading cycles are applied, and predicting its life. Analysis, experiments and numerical methods are herein applied to test case suggested by industry to investigate step by step the microswitch operation. Effects on pull-in and switch contact are investigated. Multiple electro-thermo-mechanical coupling is finally modeled to have a preliminary and comprehensive description of microswitch behavior and of its structural reliability.

  11. A novel thermo-mechanical system enhanced transdermal delivery of hydrophilic active agents by fractional ablation.

    PubMed

    Sintov, Amnon C; Hofmann, Maja A

    2016-09-25

    The Tixel is a novel device based on a thermo-mechanical ablation technology that combines a sophisticated motion and a temperature control. The fractional technology is used to transfer a very precise thermal energy to the skin thereby creating an array of microchannels, accompanying by no signs of pain or inconvenience. This study aimed to evaluate the effect of the Tixel on the skin permeability of three hydrophilic molecular models: verapamil hydrochloride, diclofenac sodium, and magnesium ascorbyl phosphate. Tixel's gold-platted stainless steel tip heated to a temperature of 400°C was applied on skin for 8ms or 9ms at a protrusion of 400μm (the distance in which the tip protrudes beyond the distance gauge). The experiments were carried out partly in vivo in humans using a fluorescent dye and a confocal microscopy and partly in vitro using porcine skin and a Franz diffusion cell system. The results obtained in this study have shown that (a) no significant collateral damage to the skin tissue and no necrosis or dermal coagulation have been noted, (b) the microchannels remained open and endured for at least 6h, and (c) the skin permeability of hydrophilic molecules, which poorly penetrate the lipophilic stratum corneum barrier, was significantly enhanced by using Tixel's pretreatment. PMID:27480396

  12. Multiscale Approach to the Physics of Ion-Beam Therapy:. Thermo-Mechanical Damage

    NASA Astrophysics Data System (ADS)

    Solov'yov, A. V.; Yakubovich, A. V.; Surdutovich, E.

    2012-01-01

    We present a brief overview of the multiscale approach towards the understanding of processes responsible for the radiation damage caused by energetic ions. This knowledge is important because it can be utilized in the ion-beam cancer therapy, which is one of the most advanced modern techniques to cure certain types of cancer. The central element of the multiscale approach is the theoretical evaluation and quantification of DNA damage within cell environment. We consider different pathways of DNA damage and focus on the the illustration of the thermo-mechanical effects caused by the propagation of ions through the biological environment and in particular on the possibility of the creation of the shock waves in the vicinity of the ion tracks. We demonstrate that at the initial stages after ion's passage the shock wave is so strong that it can contribute to the DNA damage due to large pressure gradients developed at the distances of a few nanometers from the ionic tracks. This novel mechanism of the DNA damage provides an important contribution to the cumulative bio-damage caused by low-energy secondary electrons, holes and free radicals.

  13. Rheological, thermo-mechanical, and baking properties of wheat-millet flour blends.

    PubMed

    Aprodu, Iuliana; Banu, Iuliana

    2015-07-01

    Millet has long been known as a good source of fiber and antioxidants, but only lately started to be exploited by food scientists and food industry as a consequence of increased consumer awareness. In this study, doughs and breads were produced using millet flour in different ratios (10, 20, 30, 40, and 50%) to white, dark, and whole wheat flour. The flour blends were evaluated in terms of rheological and thermo-mechanical properties. Fundamental rheological measurements revealed that the viscosity of the flour formulations increases with wheat flour-extraction rate and decreases with the addition of millet flour. Doughs behavior during mixing, overmixing, pasting, and gelling was established using the Mixolab device. The results of this bread-making process simulation indicate that dough properties become critical for the flour blends with millet levels higher than 30%. The breads were evaluated for volume, texture, and crumb-grain characteristics. The baking test and sensory evaluation results indicated that substitution levels of up to 30% millet flour could be used in composite bread flour. High levels of millet flour (40 and 50%) negatively influenced the loaf volume, crumb texture, and taste. PMID:24837596

  14. Quantifying the thermo-mechanical impact of plume arrival on continental break-up

    NASA Astrophysics Data System (ADS)

    Brune, Sascha; Popov, Anton A.; Sobolev, Stephan V.

    2013-09-01

    The arrival of a plume head at Earth's continental lithosphere is often considered to be an important factor for continental break-up. However, the impact of plume impingement on strength and duration of a rift remains unclear. In this study, we quantify the mechanical and thermal influence of a plume (i.e. lithosphere erosion) on continental break-up. To do that we apply the three-dimensional numerical code SLIM3D that features realistic elasto-visco-plastic rheology. We model the thermo-mechanical response of a segment of Earth's lithosphere that is affected both by extension as well as plume-related lithosphere erosion in order to evaluate the influence on the overall force budget. We find that lithosphere erosion leads to a moderate lithospheric strength reduction of several TN/m. In a force-limited environment, however, this strength reduction may have strong influence on the timing of continental break-up, or it may even control whether continental break-up takes place at all. Additional reduction of the lithospheric strength is likely due to the massive emplacement of dikes that follows intensive melting within the plume head.

  15. Thermal stability and thermo-mechanical properties of magnetron sputtered Cr-Al-Y-N coatings

    SciTech Connect

    Rovere, Florian; Mayrhofer, Paul H.

    2008-01-15

    Cr{sub 1-x}Al{sub x}N coatings are promising candidates for advanced machining and high temperature applications due to their good mechanical and thermal properties. Recently the authors have shown that reactive magnetron sputtering using Cr-Al targets with Al/Cr ratios of 1.5 and Y contents of 0, 2, 4, and 8 at % results in the formation of stoichiometric (Cr{sub 1-x}Al{sub x}){sub 1-y}Y{sub y}N films with Al/Cr ratios of {approx}1.2 and YN mole fractions of 0%, 2%, 4%, and 8%, respectively. Here, the impact of Y on thermal stability, structural evolution, and thermo-mechanical properties is investigated in detail. Based on in situ stress measurements, thermal analyzing, x-ray diffraction, and transmission electron microscopy studies the authors conclude that Y effectively retards diffusional processes such as recovery, precipitation of hcp-AlN and fcc-YN, grain growth, and decomposition induced N{sub 2} release. Hence, the onset temperature of the latter shifts from {approx}1010 to 1125 deg. C and the hardness after annealing at T{sub a}=1100 deg. C increases from {approx}32 to 39 GPa with increasing YN mole fraction from 0% to 8%, respectively.

  16. Thermo-mechanical modelling of cyclic gas storage applications in salt caverns

    NASA Astrophysics Data System (ADS)

    Böttcher, Norbert; Watanabe, Norihiro; Görke, Uwe-Jens; Kolditz, Olaf; Nagel, Thomas

    2016-04-01

    Due to the growing importance of renewable energy sources it becomes more and more necessary to investigate energy storage potentials. One major way to store energy is the power-to-gas concept. Excessive electrical energy can be used either to produce hydrogen or methane by electrolysis or methanation or to compress air, respectively. Those produced gases can then be stored in artificial salt caverns, which are constructed in large salt formations by solution mining. In combination with renewable energy sources, the power-to-gas concept is subjected to fluctuations. Compression and expansion of the storage gases lead to temperature differences within the salt rock. The variations can advance several metres into the host rock, influencing its material behaviour, inducing thermal stresses and altering the creep response. To investigate the temperature influence on the cavern capacity, we have developed a numerical model to simulate the thermo-mechanical behaviour of salt caverns during cyclic gas storage. The model considers the thermodynamic behaviour of the stored gases as well as the heat transport and the temperature dependent material properties of the host rock. Therefore, we utilized well-known constitutive thermo-visco-plastic material models, implemented into the open source-scientific software OpenGeoSys. Both thermal and mechanical processes are solved using a finite element approach, connected via a staggered coupling scheme. The model allows the assessment of the structural safety as well as the convergence of the salt caverns.

  17. The thermo-mechanical architecture and TPS configuration of the pre-X vehicle

    NASA Astrophysics Data System (ADS)

    Leleu, F.; Watillon, Ph.; Moulin, J.; Lacombe, A.; Soyris, Ph.

    2005-02-01

    This paper reviews both the thermo-mechanical architecture and the configuration of the thermal protection system (TPS) of the Pre-X vehicle, as presented at the System Concept Review that concluded the evaluation phase in June 2002. Pre-X is a first generation experimental re-entry vehicle. It aims mainly at gathering aerothermodynamics (ATD) data in the hypersonic regime and at testing reusable thermal protections and hot structures, currently available in Europe, which could be used for a RLV. The mechanical architecture, based on an aircraft like metallic structure, is presented, as well as the general configuration of the TPS. The experimentation plan on thermal protections is detailed; it includes ceramic matrix composite (CMC) hot structures, ceramic shingles and panels, metallic components, flexible blankets. The outcomes of the analyses already performed on critical issues are summarized (oxidation regime of C/SiC, radiation box analysis on the nose cap, windward and body-flaps pre-design and pre-sizing). Finally, guidelines are proposed for the development plan of the TPS and an outline is given on tasks which are under investigation.

  18. Thermo-mechanical actuator-based miniature tagging module for localization in capsule endoscopy

    NASA Astrophysics Data System (ADS)

    Chandrappan, Jayakrishnan; Ruiqi, Lim; Su, Nandar; Yen Yi, Germaine Hoe; Vaidyanathan, Kripesh

    2011-04-01

    Capsule endoscopy is a frontline medical diagnostic tool for the gastro intestinal tract disorders. During diagnosis, efficient localization techniques are essential to specify a pathological area that may require further diagnosis or treatment. This paper presents the development of a miniature tagging module that relies on a novel concept to label the region of interest and has the potential to integrate with a capsule endoscope. The tagging module is a compact thermo-mechanical actuator loaded with a biocompatible micro tag. A low power microheater attached to the module serves as the thermal igniter for the mechanical actuator. At optimum temperature, the actuator releases the micro tag instantly and penetrates the mucosa layer of a GI tract, region of interest. Ex vivo animal trials are conducted to verify the feasibility of the tagging module concept. X-ray imaging is used to detect the location of the micro tag embedded in the GI tract wall. The method is successful, and radiopaque micro tags can provide valuable pre-operative position information on the infected area to facilitate further clinical procedures.

  19. High-field magneto-thermo-mechanical testing system for characterizing multiferroic bulk alloys.

    PubMed

    Bruno, Nickolaus M; Karaman, Ibrahim; Ross, Joseph H; Chumlyakov, Yuriy I

    2015-11-01

    Multiferroic meta-magnetic shape memory alloys are well known for exhibiting large magnetic field induced actuation strains, giant magnetocaloric effects, magneto-resistance, and structural and magnetic glassy behaviors. Thus, they are candidates for improving modern day sensing, actuation, magneto-resistance, and solid-state refrigeration processes. Until now, however, experimental apparatuses have typically been able to probe a limited ferroic parameter space in these materials, i.e., only concurrent thermal and mechanical responses, or magnetic and thermal responses. To overcome this barrier and better understand the coupling of multiple fields on materials behavior, a magneto-thermo-mechanical characterization device has been designed and implemented. This device is capable of compressing a specimen at load levels up to 5300 N collinearly with applied fields up to 9 T between temperatures of -100 °C and 120 °C. Uniaxial stress, strain, temperature, magnetic field, and the volumetric average magnetization have been simultaneously measured under mixed loading conditions on a NiCoMnIn meta-magnetic shape memory alloy and a few selected results are presented here. PMID:26628146

  20. Thermo-mechanical Fatigue Failure of Thermal Barrier Coated Superalloy Specimen

    NASA Astrophysics Data System (ADS)

    Subramanian, Rajivgandhi; Mori, Yuzuru; Yamagishi, Satoshi; Okazaki, Masakazu

    2015-09-01

    Failure behavior of thermal barrier coated (TBC) Ni-based superalloy specimens were studied from the aspect of the effect of bond coat material behavior on low cycle fatigue (LCF) and thermo-mechanical fatigue (TMF) at various temperatures and under various loading conditions. Initially, monotonic tensile tests were carried out on a MCrAlY alloy bond coat material in the temperature range of 298 K to 1273 K (25 °C to 1000 °C). Special attention was paid to understand the ductile to brittle transition temperature (DBTT). Next, LCF and TMF tests were carried out on the thermal barrier coated Ni-based alloy IN738 specimen. After these tests, the specimens were sectioned to understand their failure mechanisms on the basis of DBTT of the bond coat material. Experimental results demonstrated that the LCF and TMF lives of the TBC specimen were closely related to the DBTT of the bond coat material, and also the TMF lives were different from those of LCF tests. It has also been observed that the crack density in the bond coat in the TBC specimen was significantly dependent on the test conditions. More importantly, not only the number of cracks but also the crack penetration probability into substrate were shown to be sensitive to the DBTT.

  1. High-field magneto-thermo-mechanical testing system for characterizing multiferroic bulk alloys

    NASA Astrophysics Data System (ADS)

    Bruno, Nickolaus M.; Karaman, Ibrahim; Ross, Joseph H.; Chumlyakov, Yuriy I.

    2015-11-01

    Multiferroic meta-magnetic shape memory alloys are well known for exhibiting large magnetic field induced actuation strains, giant magnetocaloric effects, magneto-resistance, and structural and magnetic glassy behaviors. Thus, they are candidates for improving modern day sensing, actuation, magneto-resistance, and solid-state refrigeration processes. Until now, however, experimental apparatuses have typically been able to probe a limited ferroic parameter space in these materials, i.e., only concurrent thermal and mechanical responses, or magnetic and thermal responses. To overcome this barrier and better understand the coupling of multiple fields on materials behavior, a magneto-thermo-mechanical characterization device has been designed and implemented. This device is capable of compressing a specimen at load levels up to 5300 N collinearly with applied fields up to 9 T between temperatures of -100 °C and 120 °C. Uniaxial stress, strain, temperature, magnetic field, and the volumetric average magnetization have been simultaneously measured under mixed loading conditions on a NiCoMnIn meta-magnetic shape memory alloy and a few selected results are presented here.

  2. Thermo-mechanical toner transfer for high-quality digital image correlation speckle patterns

    NASA Astrophysics Data System (ADS)

    Mazzoleni, Paolo; Zappa, Emanuele; Matta, Fabio; Sutton, Michael A.

    2015-12-01

    The accuracy and spatial resolution of full-field deformation measurements performed through digital image correlation are greatly affected by the frequency content of the speckle pattern, which can be effectively controlled using particles with well-defined and consistent shape, size and spacing. This paper introduces a novel toner-transfer technique to impress a well-defined and repeatable speckle pattern on plane and curved surfaces of metallic and cement composite specimens. The speckle pattern is numerically designed, printed on paper using a standard laser printer, and transferred onto the measurement surface via a thermo-mechanical process. The tuning procedure to compensate for the difference between designed and toner-transferred actual speckle size is presented. Based on this evidence, the applicability of the technique is discussed with respect to surface material, dimensions and geometry. Proof of concept of the proposed toner-transfer technique is then demonstrated for the case of a quenched and partitioned welded steel plate subjected to uniaxial tensile loading, and for an aluminum plate exposed to temperatures up to 70% of the melting point of aluminum and past the melting point of typical printer toner powder.

  3. Thermo-mechanical properties of W/Mo markers coatings deposited on bulk W

    NASA Astrophysics Data System (ADS)

    Grigore, E.; Ruset, C.; Gherendi, M.; Chioibasu, D.; Hakola, A.; contributors, JET

    2016-02-01

    In the present paper marker structures consisting of W/Mo layers were deposited on bulk W samples by using a modified CMSII method. This technology, compared to standard CMSII, prevents the formation of nano-pore structures at interfaces. The thicknesses of the markers were in the range 20-35 μm to balance the requirements associated with the wall erosion in ITER and thermo-mechanical performances. The coatings structure and composition were evaluated by glow discharge optical emission spectrometry (GDOES), and energy dispersive x-ray spectroscopy measurements (EDX). The adhesion of the coatings to the substrate has been assessed by scratch test method. In order to evaluate their effectiveness as potential markers for fusion applications, the marker coatings have been tested in an electron beam facility at a temperature of 1000 °C and a power density of about 3 MW m-2. A number of 300 pulses with duration of 420 s (35 testing hours) were applied on the marker coated samples.

  4. Nano-precipitation Strengthened G91 by Thermo-mechanical Treatment Optimization

    NASA Astrophysics Data System (ADS)

    Vivas, J.; Celada-Casero, C.; San Martín, D.; Serrano, M.; Urones-Garrote, E.; Adeva, P.; Aranda, M. M.; Capdevila, C.

    2016-06-01

    The increase of thermal efficiency in power plants has been the main driving force to develop Ferritic/Martensitic steels for structural applications capable of operating at 923 K (650 °C) and higher. It has been clarified in previous works that nano-sized precipitates and its distribution are the key factors controlling the stability of the microstructure at high operating temperatures. Based on the science of precipitate strengthening, the aim of this work is to optimize the thermo-mechanical treatment in a commercial creep-resistant steel (G91) to achieve a microstructure where MX precipitates present a suitable size and distribution. The alternative processing route proposed here allows gaining an increase up to 40 pct in yield strength at 973 K (700 °C) compared to the commercial steel. The results of small punch test carried out at room temperature showed that the improvement in strength was obtained without loss of ductility. This fact was attributed to a finer and more homogeneous dispersion of MX precipitates in comparison to the commercial steel.

  5. Reliable high-power diode lasers: thermo-mechanical fatigue aspects

    NASA Astrophysics Data System (ADS)

    Klumel, Genady; Gridish, Yaakov; Szafranek, Igor; Karni, Yoram

    2006-02-01

    High power water-cooled diode lasers are finding increasing demand in biomedical, cosmetic and industrial applications, where repetitive cw (continuous wave) and pulsed cw operation modes are required. When operating in such modes, the lasers experience numerous complete thermal cycles between "cold" heat sink temperature and the "hot" temperature typical of thermally equilibrated cw operation. It is clearly demonstrated that the main failure mechanism directly linked to repetitive cw operation is thermo-mechanical fatigue of the solder joints adjacent to the laser bars, especially when "soft" solders are used. Analyses of the bonding interfaces were carried out using scanning electron microscopy. It was observed that intermetallic compounds, formed already during the bonding process, lead to the solders fatigue both on the p- and n-side of the laser bar. Fatigue failure of solder joints in repetitive cw operation reduces useful lifetime of the stacks to hundreds hours, in comparison with more than 10,000 hours lifetime typically demonstrated in commonly adopted non-stop cw reliability testing programs. It is shown, that proper selection of package materials and solders, careful design of fatigue sensitive parts and burn-in screening in the hard pulse operation mode allow considerable increase of lifetime and reliability, without compromising the device efficiency, optical power density and compactness.

  6. FEA Based Tool Life Quantity Estimation of Hot Forging Dies Under Cyclic Thermo-Mechanical Loads

    NASA Astrophysics Data System (ADS)

    Behrens, B.-A.; Bouguecha, A.; Schäfer, F.; Hadifi, T.

    2011-01-01

    Hot forging dies are exposed during service to a combination of cyclic thermo-mechanical, tribological and chemical loads. Besides abrasive and adhesive wear on the die surface, fatigue crack initiation with subsequent fracture is one of the most frequent causes of failure. In order to extend the tool life, the finite element analysis (FEA) may serve as a means for process design and process optimisation. So far the FEA based estimation of the production cycles until initial cracking is limited as tool material behaviour due to repeated loading is not captured with the required accuracy. Material models which are able to account for cyclic effects are not verified for the fatigue life predictions of forging dies. Furthermore fatigue properties from strain controlled fatigue tests of relevant hot work steels are to date not available to allow for a close-to-reality fatigue life prediction. Two industrial forging processes, where clear fatigue crack initiation has been observed are considered for a fatigue analysis. For this purpose the relevant tool components are modelled with elasto-plastic material behaviour. The predicted sites, where crack initiation occurs, agree with the ones observed on the real die component.

  7. Thermo-mechanical efficiency of the bimetallic strip heat engine at the macro-scale and micro-scale

    NASA Astrophysics Data System (ADS)

    Arnaud, A.; Boughaleb, J.; Monfray, S.; Boeuf, F.; Cugat, O.; Skotnicki, T.

    2015-10-01

    Bimetallic strip heat engines are energy harvesters that exploit the thermo-mechanical properties of bistable bimetallic membranes to convert heat into mechanical energy. They thus represent a solution to transform low-grade heat into electrical energy if the bimetallic membrane is coupled with an electro-mechanical transducer. The simplicity of these devices allows us to consider their miniaturization using MEMS fabrication techniques. In order to design and optimize these devices at the macro-scale and micro-scale, this article proposes an explanation of the origin of the thermal snap-through by giving the expressions of the constitutive equations of composite beams. This allows us to evaluate the capability of bimetallic strips to convert heat into mechanical energy whatever their size is, and to give the theoretical thermo-mechanical efficiencies which can be obtained with these harvesters.

  8. Thermo-mechanical testing of Li?ceramic for the helium cooled pebble bed (HCPB) breeding blanket

    NASA Astrophysics Data System (ADS)

    Dell'Orco, G.; Ancona, A.; DiMaio, A.; Simoncini, M.; Vella, G.

    2004-08-01

    The helium cooled pebble bed (HCPB) Test blanket module (TBM) for the DEMO Reactor foresees the utilization of lithiate ceramics as breeder in form of pebble beds. The pebbles are organized in several layers alternatively stacked among couples of cooling plates (CP). ENEA has launched an experimental programme for the out-of-pile thermo-mechanical testing of mock-ups simulating a portion of the HCPB-TBM. The programme foresees the fabrication and testing of different mock-ups, to be tested in the HE-FUS3 facility at ENEA Brasimone. The paper describes the HELICHETTA III campaign carried-out in 2003. In particular, the test section layout, the pebble filling procedure, the experimental set-up and the results of the relevant thermo-mechanical test are herewith presented.

  9. A geometrical multi-scale numerical method for coupled hygro-thermo-mechanical problems in photovoltaic laminates

    NASA Astrophysics Data System (ADS)

    Lenarda, P.; Paggi, M.

    2016-06-01

    A comprehensive computational framework based on the finite element method for the simulation of coupled hygro-thermo-mechanical problems in photovoltaic laminates is herein proposed. While the thermo-mechanical problem takes place in the three-dimensional space of the laminate, moisture diffusion occurs in a two-dimensional domain represented by the polymeric layers and by the vertical channel cracks in the solar cells. Therefore, a geometrical multi-scale solution strategy is pursued by solving the partial differential equations governing heat transfer and thermo-elasticity in the three-dimensional space, and the partial differential equation for moisture diffusion in the two dimensional domains. By exploiting a staggered scheme, the thermo-mechanical problem is solved first via a fully implicit solution scheme in space and time, with a specific treatment of the polymeric layers as zero-thickness interfaces whose constitutive response is governed by a novel thermo-visco-elastic cohesive zone model based on fractional calculus. Temperature and relative displacements along the domains where moisture diffusion takes place are then projected to the finite element model of diffusion, coupled with the thermo-mechanical problem by the temperature and crack opening dependent diffusion coefficient. The application of the proposed method to photovoltaic modules pinpoints two important physical aspects: (i) moisture diffusion in humidity freeze tests with a temperature dependent diffusivity is a much slower process than in the case of a constant diffusion coefficient; (ii) channel cracks through Silicon solar cells significantly enhance moisture diffusion and electric degradation, as confirmed by experimental tests.

  10. A geometrical multi-scale numerical method for coupled hygro-thermo-mechanical problems in photovoltaic laminates

    NASA Astrophysics Data System (ADS)

    Lenarda, P.; Paggi, M.

    2016-02-01

    A comprehensive computational framework based on the finite element method for the simulation of coupled hygro-thermo-mechanical problems in photovoltaic laminates is herein proposed. While the thermo-mechanical problem takes place in the three-dimensional space of the laminate, moisture diffusion occurs in a two-dimensional domain represented by the polymeric layers and by the vertical channel cracks in the solar cells. Therefore, a geometrical multi-scale solution strategy is pursued by solving the partial differential equations governing heat transfer and thermo-elasticity in the three-dimensional space, and the partial differential equation for moisture diffusion in the two dimensional domains. By exploiting a staggered scheme, the thermo-mechanical problem is solved first via a fully implicit solution scheme in space and time, with a specific treatment of the polymeric layers as zero-thickness interfaces whose constitutive response is governed by a novel thermo-visco-elastic cohesive zone model based on fractional calculus. Temperature and relative displacements along the domains where moisture diffusion takes place are then projected to the finite element model of diffusion, coupled with the thermo-mechanical problem by the temperature and crack opening dependent diffusion coefficient. The application of the proposed method to photovoltaic modules pinpoints two important physical aspects: (i) moisture diffusion in humidity freeze tests with a temperature dependent diffusivity is a much slower process than in the case of a constant diffusion coefficient; (ii) channel cracks through Silicon solar cells significantly enhance moisture diffusion and electric degradation, as confirmed by experimental tests.

  11. Thermo-mechanical Modelling of Pebble Beds in Fusion Blankets and its Implementation by a Return-Mapping Algorithm

    SciTech Connect

    Gan, Yixiang; Kamlah, Marc

    2008-07-01

    In this investigation, a thermo-mechanical model of pebble beds is adopted and developed based on experiments by Dr. Reimann at Forschungszentrum Karlsruhe (FZK). The framework of the present material model is composed of a non-linear elastic law, the Drucker-Prager-Cap theory, and a modified creep law. Furthermore, the volumetric inelastic strain dependent thermal conductivity of beryllium pebble beds is taken into account and full thermo-mechanical coupling is considered. Investigation showed that the Drucker-Prager-Cap model implemented in ABAQUS can not fulfill the requirements of both the prediction of large creep strains and the hardening behaviour caused by creep, which are of importance with respect to the application of pebble beds in fusion blankets. Therefore, UMAT (user defined material's mechanical behaviour) and UMATHT (user defined material's thermal behaviour) routines are used to re-implement the present thermo-mechanical model in ABAQUS. An elastic predictor radial return mapping algorithm is used to solve the non-associated plasticity iteratively, and a proper tangent stiffness matrix is obtained for cost-efficiency in the calculation. An explicit creep mechanism is adopted for the prediction of time-dependent behaviour in order to represent large creep strains in high temperature. Finally, the thermo-mechanical interactions are implemented in a UMATHT routine for the coupled analysis. The oedometric compression tests and creep tests of pebble beds at different temperatures are simulated with the help of the present UMAT and UMATHT routines, and the comparison between the simulation and the experiments is made. (authors)

  12. Fundamental study of failure mechanisms of pressure vessels under thermo-mechanical cycling in multiphase environments

    NASA Astrophysics Data System (ADS)

    Penso Mula, Jorge Antonio

    -subroutine process simulation was able to capture the important aspects of the thermo-mechanical cycle that influence the thermal and stress gradients in the shell.

  13. A Study of Thermo-mechanically Processed High Stiffness NiTiCo Shape Memory Alloy

    NASA Astrophysics Data System (ADS)

    Manjeri, R. M.; Norwich, D.; Sczerzenie, F.; Huang, X.; Long, M.; Ehrlinspiel, M.

    2016-03-01

    This work investigates a vacuum induction melted-vacuum arc re-melted (VIM-VAR) and thermo-mechanically processed ternary NiTiCo shape memory alloy. The NiTiCo ingot was hot processed to 6.35-mm-diameter coiled wire. The coiled wire was subsequently cold drawn to a final wire diameter of 0.53 mm, with interpass anneals. The wires were shape set at 450 °C for 3.5 min. After electropolishing, the wires were subjected to microstructural, thermal, and mechanical characterization studies. Microstructural analysis was performed by transmission electron microscope (TEM), thermal analyses by differential scanning calorimeter (DSC), and bend-free recovery and mechanical testing by uniaxial tensile testing. TEM did not reveal Ni-rich precipitates—either at the grain boundary or in the grain interior. Energy dispersive x-ray spectroscopy showed a uniform distribution of Ni, Ti, and Co in the sample. The DSC results on the shape set wire showed a single-step transformation between the austenite and the R-phase, in the forward and reverse directions. Cyclic tensile tests of the shape set wire, processed under optimum conditions, showed minimum residual strain and a stable upper plateau stress. Further, the fatigue behavior of NiTi and NiTiCo alloys was studied by rotating beam testing. The results showed that the fatigue properties of NiTiCo, under zero mean strain, are equivalent to that of binary NiTi in the high-cycle and medium-cycle regimes, taking into account the higher stiffness of NiTiCo. The above analyses helped in establishing the processing-structure-property correlation in a VIM-VAR-melted NiTiCo shape memory alloy.

  14. Modeling of thermo-mechanical and irradiation behavior of mixed oxide fuel for sodium fast reactors

    NASA Astrophysics Data System (ADS)

    Karahan, Aydın; Buongiorno, Jacopo

    2010-01-01

    An engineering code to model the irradiation behavior of UO2-PuO2 mixed oxide fuel pins in sodium-cooled fast reactors was developed. The code was named fuel engineering and structural analysis tool (FEAST-OXIDE). FEAST-OXIDE has several modules working in coupled form with an explicit numerical algorithm. These modules describe: (1) fission gas release and swelling, (2) fuel chemistry and restructuring, (3) temperature distribution, (4) fuel-clad chemical interaction and (5) fuel-clad mechanical analysis. Given the fuel pin geometry, composition and irradiation history, FEAST-OXIDE can analyze fuel and cladding thermo-mechanical behavior at both steady-state and design-basis transient scenarios. The code was written in FORTRAN-90 program language. The mechanical analysis module implements the LIFE algorithm. Fission gas release and swelling behavior is described by the OGRES and NEFIG models. However, the original OGRES model has been extended to include the effects of joint oxide gain (JOG) formation on fission gas release and swelling. A detailed fuel chemistry model has been included to describe the cesium radial migration and JOG formation, oxygen and plutonium radial distribution and the axial migration of cesium. The fuel restructuring model includes the effects of as-fabricated porosity migration, irradiation-induced fuel densification, grain growth, hot pressing and fuel cracking and relocation. Finally, a kinetics model is included to predict the clad wastage formation. FEAST-OXIDE predictions have been compared to the available FFTF, EBR-II and JOYO databases, as well as the LIFE-4 code predictions. The agreement was found to be satisfactory for steady-state and slow-ramp over-power accidents.

  15. Thermo-mechanically coupled subduction with a free surface using ASPECT

    NASA Astrophysics Data System (ADS)

    Fraters, Menno; Glerum, Anne; Thieulot, Cedric; Spakman, Wim

    2014-05-01

    ASPECT (Kronbichler et al., 2012), short for Advanced Solver for Problems in Earth's ConvecTion, is a new Finite Element code which was originally designed for thermally driven (mantle) convection and is built on state of the art numerical methods (adaptive mesh refinement, linear and nonlinear solver, stabilization of transport dominated processes and a high scalability on multiple processors). Here we present an application of ASPECT to modeling of fully thermo-mechanically coupled subduction. Our subduction model contains three different compositions: a crustal composition on top of both the subducting slab and the overriding plate, a mantle composition and a sticky air composition, which allows for simulating a free surface for modeling topography build-up. We implemented a visco-plastic rheology using frictional plasticity and a composite viscosity defined by diffusion and dislocation creep. The lithospheric mantle has the same composition as the mantle but has a higher viscosity because of a lower temperature. The temperature field is implemented in ASPECT as follows: a linear temperature gradient for the lithosphere and an adiabatic geotherm for the sublithospheric mantle. Initial slab temperature is defined using the analytical solution of McKenzie (1970). The plates can be pushed from the sides of the model, and it is possible to define an additional independent mantle in/out flow through the boundaries. We will show a preliminary set of models, highlighting the codes capabilities, such as the Adaptive Mesh Refinement, topography development and the influence of mantle flow on the subduction evolution. Kronbichler, M., Heister, T., and Bangerth, W. (2012), High accuracy mantle convection simulation through modern numerical methods, Geophysical Journal International,191, 12-29, doi:10.1111/j.1365-246X.2012.05609. McKenzie, D.P. (1970), Temperature and potential temperature beneath island arcs, Teconophysics, 10, 357-366, doi:10.1016/0040-1951(70)90115-0.

  16. Inherited basin inversion: thermo-mechanical modeling and comparison with the western External Alps.

    NASA Astrophysics Data System (ADS)

    Lafosse, Manfred; Boutoux, Alexandre; Bellahsen, Nicolas; Le Pourhiet, Laetitia

    2015-04-01

    Basement involved shortening in the external zones of orogen is a common structural style and most of the time deformation patterns are controlled by reactivation/inversion of inherited structures, as continental collision commonly involves stretched and thinned continental margins. If inversion of inherited basins and reactivation of normal faults were documented in several fold-and-thrust-belts, it is not the case in more internal domains. We are here interested in the case where the crust experiences significant tectonic burial (down to greenschist facies) before its shortening. Here, we present thermo-mechanical models in order to investigate the relative influence of fault friction and tectonic burial depth on reactivation patterns in inherited syn-rift basins during shortening. The results of the parametric modeling study show that, for only 2 km of tectonic burial, the presence of weak basins on its own is sufficient to localize the strain by increasing the rate of growth of the crustal scale folds. Even for relatively small friction angle within the inherited faults, i.e. 10°, those are only partially reactivated in presence of weak basin when burial is small (2 km). From moderate (4 km) to large tectonic burial (8 km), fault reactivation is inhibited. Normal faults become strongly deformed and nearly vertical and lock after only few percent shortening. From low burial to high burial, the normal faults tend to be less reactivated, the basement tend to be more folded and the cover dysharmonically folded. We compare these results to the external Western Alps from the Valence basin to the Penninic frontal thrust (at the latitude of Bourg d'Oisans). We show that External Crystalline Massifs basement and cover geometries can indeed be explained by shortening under a 10 km tectonic burial. In such conditions, the normal faults are not reactivated, the basement presents distributed shear zones, and no cover décollement. Further West, where no tectonic burial

  17. The long-term seismic cycle in collisional margins: insights from Seismo-Thermo-Mechanical models

    NASA Astrophysics Data System (ADS)

    Dal Zilio, L.; van Dinther, Y.; Gerya, T.

    2015-12-01

    The April 25, 2015, Mw 7.8 Gorkha earthquake is the largest one in the Nepal Himalaya since 1934. Since the foreland part of it is densely populated, these events represent a considerable seismic hazard. The restricted direct observations in time and space in combination with tectonic and rheological complexities, however, pose a difficult problem for both seismic hazard assessment and modeling efforts. In this study we for the first time simulate cycles of spontaneous earthquake-like ruptures on non a-priori defined faults within a generic continental collision zone. We use the Seismo-Thermo-Mechanical (STM) numerical modeling approach, which is based on a continuum, viscoelastoplastic code I2ELVIS and is validated for seismic cycle applications against a laboratory model and natural observations (van Dinther et al., 2013a, b). The 2-D model setup consists of two continental plates separated by an oceanic plate, in which the incipient subduction phase is followed by continent-continent collision. In different collisional stages, we evaluate a non-associative Drucker-Prager plasticity yield criterion with pressure dependent yield strength and a strongly rate-dependent friction formulation. Our results show physically consistent emergence of complex rupture paths, both on- and off-main frontal thrust. Assuming different physical properties of tectonic nappes, we find that ruptures propagate following rheological or tectonic discontinuities. Our findings suggest that the interseismic coupling of the main-thrust affects the seismic cycle of the entire orogenic belt. While thrust-faulting events mainly occur on the main frontal thrust, normal-faulting events spread throughout the orogenic belt as a consequence of gravitational extension. Results from an event detection algorithm shows events in the deeper portions of the orogenic belt, both within the oceanic slab and near the bottom of the wedge where material is squeezed between stiff lithospheric mantle portions.

  18. Seismo-thermo-mechanical modeling of mature and immature transform faults

    NASA Astrophysics Data System (ADS)

    Preuss, Simon; Gerya, Taras; van Dinther, Ylona

    2016-04-01

    Transform faults (TF) are subdivided into continental and oceanic ones due to their markedly different tectonic position, structure, surface expression, dynamics and seismicity. Both continental and oceanic TFs are zones of rheological weakness, which is a pre-requisite for their existence and long-term stability. Compared to subduction zones, TFs are typically characterized by smaller earthquake magnitudes as both their potential seismogenic width and length are reduced. However, a few very large magnitude (Mw>8) strike-slip events were documented, which are presumably related to the generation of new transform boundaries and/or sudden reactivation of pre-existing fossil structures. In particular, the 11 April 2012 Sumatra Mw 8.6 earthquake is challenging the general concept that such high magnitude events only occur at megathrusts. Hence, the processes of TF nucleation, propagation and their direct relation to the seismic cycle and long-term deformation at both oceanic and continental transforms needs to be investigated jointly to overcome the restricted direct observations in time and space. To gain fundamental understanding of involved physical processes the numerical seismo-thermo-mechanical (STM) modeling approach, validated in a subduction zone setting (Van Dinther et al. 2013), will be adapted for TFs. A simple 2D plane view model geometry using visco-elasto-plastic material behavior will be adopted. We will study and compare seismicity patterns and evolution in two end member TF setups, each with strain-dependent and rate-dependent brittle-plastic weakening processes: (1) A single weak and mature transform fault separating two strong plates (e.g., in between oceanic ridges) and (2) A nucleating or evolving (continental) TF system with disconnected predefined faults within a plate subjected to simple shear deformation (e.g., San Andreas Fault system). The modeling of TFs provides a first tool to establish the STM model approach for transform faults in a

  19. Thermo-mechanical controls on the mode of continental collision in the SE Carpathians (Romania)

    NASA Astrophysics Data System (ADS)

    Cloetingh, S. A. P. L.; Burov, E.; Matenco, L.; Toussaint, G.; Bertotti, G.; Andriessen, P. A. M.; Wortel, M. J. R.; Spakman, W.

    2004-01-01

    The Carpathians orogenic system, with its along-arc variations in topography developed in the aftermath of continental collision, is associated with unusual foredeep basins, large-scale strain and seismicity concentration and high-velocity mantle bodies. The East Carpathians continental collision was non-cylindrical, leading to large-scale variations in thrust nappe kinematics, orogenic uplift patterns and foredeep subsidence, controlled by the mechanics and geometry of the lower plate. Thermo-mechanical modelling demonstrates that in this low-rate convergence regime, the subducted lithosphere had enough time to interact with the mantle to advance towards a thermal resettlement. This is favored by the low degree of metamorphism, mechanical weakness of the lower plate and the lack of active surface processes at the contact with and in the upper plate. In contrast, low-buoyant, thick lower crust and active surface processes keep the continuity of the slab intact and promote the development of typical foredeep basins. The model explains in a self-consistent manner the unusual geometry of the Vrancea seismogenic slab in the bend zone of the Romanian Carpathians. The model is also consistent with the presence of two high-velocity bodies inferred from seismic tomography studies and explains the depth zonation of seismicity in the Vrancea area. Differences between the northern part of East Carpathians and the southeastern bend of the Carpathians arc are largely controlled by lateral variations in crustal structure, topography emplacement and surface processes along the arc. Mechanical heterogeneity of the Carpathians subduction leads to the development of two end member modes of collision, allowing a study of these states and their transition. Lithospheric configuration and tectonic topography appear to be prime factors controlling variations in slab behavior. In the SE Carpathians, at the terminal phase of continental convergence, slab delamination, roll-back and

  20. The Moho in extensional tectonic settings: insights from thermo-mechanical models

    NASA Astrophysics Data System (ADS)

    Cloetingh, Sierd; Burov, Evgenii; Liviu, Matenco

    2013-04-01

    We review consequences for the crustal and lithospheric configuration of different models for the thermo-mechanical evolution of continental lithosphere in extensional tectonic settings. The lithospheric memory is key for the interplay of lithospheric stresses and rheological structure of the extending lithosphere and for its later tectonic reactivation. Other important factors are the temporal and spatial migration of extension and the interplay of rifting and surface processes. The mode of extension and the duration of the rifting phase required to lead to continental break-up is to a large extent controlled by the interaction of the extending plate with slab dynamics. We compare predictions from numerical models with observational constraints from a number of rifted back-arc basin settings and intraplate domains at large distance from convergent plate boundaries. We discuss the record of vertical motions during and after rifting in the context of stretching models developed to quantify rifted basin formation. The finite strength of the lithosphere has an important effect on the formation of extensional basins. This applies both to the geometry of the basin shape as well as to the record of vertical motions during and after rifting. We demonstrate a strong connection between the bulk rheological properties of Europe's lithosphere and the evolution of some of Europe's main rifts and back-arc system. The thermomechanical structure of the lithosphere has a major impact on continental breakup and associated basin migration processes, with direct relationships between rift duration and extension velocities, thermal evolution, and the role of mantle plumes. Compressional reactivation has important consequences for post-rift inversion, borderland uplift, and denudation, as illustrated by polyphase deformation of extensional back-arc basins in the Black Sea and the Pannonian Basin.

  1. Thermo-mechanical buckling analysis of FGM plate using generalized plate theory

    NASA Astrophysics Data System (ADS)

    Sharma, Kanishk; Kumar, Dinesh; Gite, Anil

    2016-05-01

    This paper investigates the thermo-mechanical buckling behavior of simply-supported FGM plate under the framework of generalized plate theory (GPT), which includes classical plate theory (CPT), first order shear deformation theory (FSDT) and higher order shear deformation theory (HSDT) as special cases. The governing equations for FGM plate under thermal and mechanical loading conditions are derived from the principle of virtual displacements and Navier-type solution is assumed for simply supported boundary condition. The efficiency and applicability of presented methodology is illustrated by considering various examples of thermal and mechanical buckling of FGM plates. The closed form solutions in the form of critical thermal and mechanical buckling loads, predicted by CPT, FSDT and HSDT are compared for different side-to-thickness of FGM plate. Subsequently, the effect of material gradation profile on critical buckling parameters is examined by evaluating the buckling response for a range of power law indexes. The effect of geometrical parameters on mechanical buckling of FGM plate under uni-axial and bi-axial loading conditions are also illustrated by calculating the critical load for various values of slenderness ratios. Furthermore a comparative analysis of critical thermal buckling loads of FGM plate for different temperature profiles is also presented. It is identified that all plate theories predicted approximately same critical buckling loads and critical buckling temperatures for thin FGM plate, however for thick FGM plates, CPT overestimates the critical buckling parameters. Moreover the critical buckling loads and critical buckling temperatures of FGM plate are found to be significantly lower than the corresponding homogenous isotropic ceramic plate (n=0).

  2. Analysis of the thermo-mechanical deformations in a hot forging tool by numerical simulation

    NASA Astrophysics Data System (ADS)

    L-Cancelos, R.; Varas, F.; Martín, E.; Viéitez, I.

    2016-03-01

    Although programs have been developed for the design of tools for hot forging, its design is still largely based on the experience of the tool maker. This obliges to build some test matrices and correct their errors to minimize distortions in the forged piece. This phase prior to mass production consumes time and material resources, which makes the final product more expensive. The forging tools are usually constituted by various parts made of different grades of steel, which in turn have different mechanical properties and therefore suffer different degrees of strain. Furthermore, the tools used in the hot forging are exposed to a thermal field that also induces strain or stress based on the degree of confinement of the piece. Therefore, the mechanical behaviour of the assembly is determined by the contact between the different pieces. The numerical simulation allows to analyse different configurations and anticipate possible defects before tool making, thus, reducing the costs of this preliminary phase. In order to improve the dimensional quality of the manufactured parts, the work presented here focuses on the application of a numerical model to a hot forging manufacturing process in order to predict the areas of the forging die subjected to large deformations. The thermo-mechanical model developed and implemented with free software (Code-Aster) includes the strains of thermal origin, strains during forge impact and contact effects. The numerical results are validated with experimental measurements in a tooling set that produces forged crankshafts for the automotive industry. The numerical results show good agreement with the experimental tests. Thereby, a very useful tool for the design of tooling sets for hot forging is achieved.

  3. Predicting the Operating Behavior of Ceramic Filters from Thermo-Mechanical Ash Properties

    SciTech Connect

    Hemmer, G.; Kasper, G.

    2002-09-19

    Stable operation, in other words the achievement of a succession of uniform filtration cycles of reasonable length is a key issue in high-temperature gas filtration with ceramic media. Its importance has rather grown in recent years, as these media gain in acceptance due to their excellent particle retention capabilities. Ash properties have been known for some time to affect the maximum operating temperature of filters. However, softening and consequently ''stickiness'' of the ash particles generally depend on composition in a complex way. Simple and accurate prediction of critical temperature ranges from ash analysis--and even more so from coal analysis--is still difficult without practical and costly trials. In general, our understanding of what exactly happens during break-down of filtration stability is still rather crude and general. Early work was based on the concept that ash particles begin to soften and sinter near the melting temperatures of low-melting, often alkaline components. This softening coincides with a fairly abrupt increase of stickiness, that can be detected with powder mechanical methods in a Jenicke shear cell as first shown by Pilz (1996) and recently confirmed by others (Kamiya et al. 2001 and 2002, Kanaoka et al. 2001). However, recording {sigma}-{tau}-diagrams is very time consuming and not the only off-line method of analyzing or predicting changes in thermo-mechanical ash behavior. Pilz found that the increase in ash stickiness near melting was accompanied by shrinkage attributed to sintering. Recent work at the University of Karlsruhe has expanded the use of such thermo-analytical methods for predicting filtration behavior (Hemmer 2001). Demonstrating their effectiveness is one objective of this paper. Finally, our intent is to show that ash softening at near melting temperatures is apparently not the only phenomenon causing problems with filtration, although its impact is certainly the ''final catastrophe''. There are other

  4. Thermo-mechanical analysis of a user filter assembly for undulator/wiggler operations at the Advanced Photon Source

    SciTech Connect

    Nian, H.L.T.; Kuzay, T.M.; Collins, J.; Shu, D.; Benson, C.; Dejus, R.

    1996-12-31

    This paper reports a thermo-mechanical study of a beamline filter (user filter) for undulator/wiggler operations. It is deployed in conjunction with the current commissioning window assembly on the APS insertion device (ID) front ends. The beamline filter at the Advanced Photon Source (APS) will eventually be used in windowless operations also. Hence survival and reasonable life expectancy of the filters under intense insertion device (ID) heat flu are crucial to the beamline operations. To accommodate various user requirements, the filter is configured to be a multi-choice type and smart to allow only those filter combinations that will be safe to operate with a given ring current and beamline insertion device gap. However, this paper addresses only the thermo-mechanical analysis of individual filter integrity and safety in all combinations possible. The current filter design is configured to have four filter frames in a cascade with each frame holding five filters. This allows a potential 625 total filter combinations. Thermal analysis for all of these combinations becomes a mammoth task considering the desired choices for filter materials (pyrolitic graphite and metallic filters), filter thicknesses, undulator gaps, and the beam currents. The paper addresses how this difficult task has been reduced to a reasonable effort and computational level. Results from thermo-mechanical analyses of the filter combinations are presented both in tabular and graphical format.

  5. Influence of Bond Coat Roughness on Life Time of APS Thermal Barrier Coating Systems under Thermo-Mechanical Load

    NASA Astrophysics Data System (ADS)

    Schmidt, Andreas; Aleksanoglu, Herman; Mao, Tongsheng; Scholz, Alfred; Berger, Christina

    The influence of the bond coat roughness on the life time of air plasma-sprayed (APS) thermal barrier coating systems (TBCs) was investigated under thermo-mechanical (TMF) load. The TBC system was applied on hollow cylindrical specimens made of the single crystal super alloy CMSX-4 in the orientation <001> with a MCrAlY-bond coat. Two different values of the bond coat roughness were investigated. In order to study the influence of the thicknesses of the thermally grown oxide layer (TGO), the specimens were isothermally oxidized at 1000 °C for a long term prior to the TMF experiments. The thermo-mechanical experiments show a higher number of cycles-to-failure for TBCs corresponding to an increase of the bond coat roughness. Furthermore, it could be demonstrated that a certain TGO thickness is needed to produce a total delamination of the top coat in the TMF experiments. This minimum thickness varies with the surface roughness of the bond coat and the TMF cycle's phase shift and strain range. Crack initiation and crack propagation were investigated by microscopical analyses, for example, SEM and EDX. Therefore most of the experiments were completed before a total delamination of the top coat occurred. On the basis of these investigations, crack initiation and crack propagation under thermo-mechanical load were described systematically.

  6. Experimental evidence of thermo-mechanical pressurization of faults during earthquakes

    NASA Astrophysics Data System (ADS)

    Violay, Marie; Di Toro, Giulio; Nielsen, Stefan; Spagnuolo, Elena; Burg, Jean-Pierre

    2015-04-01

    Earthquakes occur while fault strength decreases with increasing slip and slip rate. Thermo-mechanical pressurization of pore fluids induced by frictional heating during seismic slip is one of the possible mechanisms responsible for fault dynamic weakening. However, has not yet been observed in the laboratory. To investigate seismic slip in the presence of pore fluids, 26 friction experiments were conducted at room temperature on hollow cylinders (50/30 mm external/internal diameter) of Etna basalt (1) under room-dry conditions or immersed in water under either (2) drained conditions (constant pore pressure, preventing fluid pressurization), and (3) undrained conditions (constant pore volume). Experiments were performed by spinning two basalt cylinders with the rotary shear machine (SHIVA, INGV Rome) at target slip rates (V) of 3 m/s, displacements (δ) from 4 m to 6 m, normal stress (σn) ranging from 15 to 35 MPa and initial pore fluid pressure (Pf) of 5 MPa.The experimental data are compared with those obtained from carbonate-bearing rocks (Carrara marble). In all the experiments, the coefficient of friction μ decayed exponentially from a peak value (μp = 0.55 ∓ 0.07) at about the initiation of slip towards a steady-state value μss of 0.1 under room-dry conditions, 0.1 under drained conditions and 0.08 under undrained conditions. The shear stress decay was about 75 percent over the first 5 cm of slip, independently of the ambient conditions. However, at a given σneff, δ and V, steady state shear stress was 20 percent lower under undrained than under drained and room dry conditions. Moreover, Pf under undrained conditions increased with displacement following a power law. Conversely, Pf and σn did not vary under drained conditions. After all experiments, a continuous, 100-200 µm thick, layer of glass (Scanning Electron Microscope investigation) separated the rock cylinders, irrespective of the ambient and hydraulic conditions. In summary, the mechanical

  7. Updating the thermo-mechanical structure of the European lithosphere with subsurface temperature data

    NASA Astrophysics Data System (ADS)

    Limberger, Jon; van Wees, Jan-Diederik; Tesauro, Magdala; Bonté, Damien; Lipsey, Lindsay; Smit, Jeroen; Beekman, Fred; Cloetingh, Sierd

    2016-04-01

    As part of the EU FP7-funded Integrated Methods for Advanced Geothermal Exploration (IMAGE) project we developed a methodology to obtain an improved, physics-based thermal model of the European lithosphere. On the basis of geophysical data, the model is divided into a four layer geometry consisting of sediments, upper crust, lower crust and lithospheric mantle. The horizontal resolution is 10 by 10 km, while the vertical one is 250 m. The prior steady-state temperature distribution is calculated using vertical heat flow only. imposing as boundary conditions fixed temperatures at the surface and at the base of the lithosphere, respectively. Thermal properties, including radiogenic heat production and temperature- and pressure-dependent bulk thermal conductivity, are assigned on the base of the broad-scale lithological variation within the European crust. Further improvements of the thermal model, aiming at consistency between temperatures and heat flow observations and tectonic model predictions, are obtained by applying data assimilation. An Ensemble Kalman Filter (EnKF) is used to assimilate temperature data and improve the prior estimates of the thermal properties and the thermal field. One of the advantages of EnKF is that multiple model realisations yield uncertainties for both the thermal properties and the thermal field. Borehole temperature data are directly used for this procedure, when publically available. Regional thermal models - originally based on borehole data - are used for areas lacking any (public) borehole temperature data. A larger error is assigned to the temperature values derived from these models, in order to account for the higher uncertainty compared to direct-measured temperatures. The thermal model is also used together with compositional data to estimate the integrated strength of the lithosphere. The result is an updated thermo-mechanical model of the European lithosphere with estimated uncertainties for the thermal properties and the

  8. A Modified Wilson Cycle Scenario Based on Thermo-Mechanical Model

    NASA Astrophysics Data System (ADS)

    Baes, M.; Sobolev, S. V.

    2014-12-01

    The major problem of classical Wilson Cycle concept is the suggested conversion of the passive continental margin to the active subduction zone. Previous modeling studies assumed either unusually thick felsic continental crust at the margin (over 40 km) or unusually low lithospheric thickness (less than 70 km) to simulate this process. Here we propose a new triggering factor in subduction initiation process that is mantle suction force. Based on this proposal we suggest a modification of Wilson Cycle concept. Sometime after opening and extension of oceanic basin, continental passive margin moves over the slab remnants of the former active subduction zones in deep mantle. Such slab remnants or deep slabs of neighboring active subduction zones produce a suction mantle flow introducing additional compression at the passive margin. It results in the initiation of a new subduction zone, hence starting the closing phase of Wilson Cycle. In this scenario the weakness of continental crust near the passive margin which is inherited from the rifting phase and horizontal push force induced from far-field topographic gradient within the continent facilitate and speed up subduction initiation process. Our thermo-mechanical modeling shows that after a few tens of million years a shear zone may indeed develop along the passive margin that has typical two-layered 35 km thick continental crust and thermal lithosphere thicker than 100 km if there is a broad mantle down-welling flow below the margin. Soon after formation of this shear zone oceanic plate descends into mantle and subduction initiates. Subduction initiation occurs following over-thrusting of continental crust and retreating of future trench. In models without far-field topographic gradient within the continent subduction initiation requires weaker passive margin. Our results also indicate that subduction initiation depends on several parameters such as magnitude, domain size and location of suction mantle flow

  9. Modelling late-orogenic collapse: A combined thermo-mechanical and chemical approach

    NASA Astrophysics Data System (ADS)

    Kaislaniemi, Lars; van Hunen, Jeroen; Bouilhol, Pierre; Allen, Mark B.

    2015-04-01

    We have explored the geodynamics of late-orogenic collapse via numerical models to study the effects of lithospheric thinning on mantle and lower crustal melting. Our goal is to better understand the formation of migmatitic terrains and the role of mantle melt in generating the geochemical spectrum of granitoids observed during the lithospheric re-equilibration. These numerical models combine finite elements thermo-mechanical modelling coupled with a Gibbs free energy minimization strategy that allow tracking melt composition. Our models assume a "jelly sandwich" strength profile of the lithosphere and the existence of sub-lithospheric small-scale convection caused by the increased post-subductional mantle water contents. The models take into account the viscosity lowering effects of water and partial melts, and dynamically adjust the composition of the mantle and crustal residue after extraction of partial melts. Effects of mantle magmas underplating the crust have been studied. Using Gibbs energy minimization allows for precise tracking of the crustal melt composition (major oxides) as a function of time and location. Our results show that minor lithosphere thinning causing low degree lower crustal melting can grow into large scale lithospheric mantle delamination via a positive feedback mechanism between the thinning of the lithosphere and the strength weakening by the partial melts in the lower crust. The melt percolation threshold (percentage of melt at which melts are extracted) affects this feedback mechanism: Extracting melts disable the weakening effect by the partial melts, but also removes most of the water in the source, leaving behind a depleted high viscosity residue layer. For this reason we also found that underplating of mantle melts below the crust initially enhances the positive feedback in lithosphere thinning, but overall has no major - or has even negative - impact on the lithosphere thinning and crustal melting. If asthenospheric melts are

  10. Investigation on thermo-mechanical instability of porous low dielectric constant materials

    NASA Astrophysics Data System (ADS)

    Zin, Emil Hyunbae

    This study investigates the structural stability of porous low dielectric constant materials (PLK) under thermal and mechanical load and the influence of contributing factors including porosity as intrinsic factor and plasma damage and moisture absorption as extrinsic factors on thermo-mechanical instability of PLK in advanced Cu/PLK interconnects. For this purpose, a ball indentation creep test technique was developed to examine the thermal and mechanical instability of PLK at relevant load and temperature conditions in the interconnect structure. Our exploration with the ball indentation creep test found that PLK films plastically deforms with time, indicating that viscoplastic deformation does occur under relevant conditions of PLK processing. On the basis of the results that the increase of the indentation depth with time shows more noticeable difference in PLK films with higher porosity, plasma exposure, and moisture absorption, it is our belief that PLK stability is greatly affected by porosity, plasma damage and moisture. Viscous flow was found to be mechanism for the viscoplastic deformation at the temperature and load of real PLK integration processing. This finding was obtained from the facts that the kinetics of the indentation creep fit very well with the viscous flow model and the extracted stress exponent is close to unity. Based on the results of temperature dependence in all PLK films, the activation energy(~1.5eV) of the viscosity back calculated from the experimental value of the kinetics was found to be much small than that of a pure glass (> 4eV). This suggests that the viscous flow of PLK is controlled by chemical reaction happening in PLK matrix. The FT-IR measurement for the examination of chemical bond reconfiguration shows that the intensity of Si-OH bonds increases with the flow while that of Si-O-Si, -CHX and Si-CH 3 bonds decreases, indicating that chemical reactions are involved in the deformation process. From these findings, it is

  11. MPP disk subsystem

    NASA Technical Reports Server (NTRS)

    Hudgins, W. A.

    1984-01-01

    A disk subsystem for the Massively Parallel processor (MPP) is designed to the block diagram level. The subsystem is capable of storing 4,992 megabytes of data, expandable to 39,936 megabytes. The subsystem is capable of transferring data to the MPP Staging Memory at a rate of 25 megabytes/second, expandable to 100 megabytes/second. A lower cost disk subsystem is also presented. This alternate subsystem is capable of storing 3,744 megabytes with a transfer rate of 10.6 megabyte/second.

  12. Insights from Thermo-Mechanically Coupled Modeling of High-Elevation Regions of the Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Sommers, A. N.; Rajaram, H.; Colgan, W. T.

    2014-12-01

    As observations become more plentiful through remote sensing and numerical models become increasingly sophisticated, a clear priority of the ice sheet modeling community is to compare model simulations with observations. Temperature and velocity conditions within the Greenland ice sheet and at the bed remain largely unknown with the exception of sparse borehole measurements, but much can be inferred from rigorous thermo-mechanically coupled modeling. Surface velocities on the Greenland ice sheet are well constrained, both from satellite imagery and field observations. We take advantage of the observed surface velocities at the PARCA stakes around the 2,000m elevation contour of the ice sheet as modeling targets that represent a broad range of flow characteristics in different regions. Prescribing ice geometry, we use a two-dimensional thermo-mechanically coupled model to calculate 'steady-state' velocity and temperature profiles throughout the depth of the ice along flowlines from the main divide to the 2,000m elevation contour. Vertical velocity calculations are based on first principles of mass conservation, accounting for convergence and divergence of the streamtube width, and the enthalpy-based temperature calculations also incorporate the effects of liquid water content in temperate ice through the flow law parameter. Numerous insights from our simulations are presented for different regions, such as the influence of variable geothermal heat flux, the treatment of basal boundary conditions, and appropriate enhancement factors based on the age of ice. Results indicate that areas of temperate bed do exist in the high-elevation interior in certain sections of Greenland. Also highlighted is the importance of including temperature calculations in ice sheet modeling, particularly in regions with a temperate bed. For example, on the west coast, computations assuming a constant temperature of -5°C result in a 41% underestimation of the surface velocity at the 2,000m

  13. Thermo-mechanical History of a Friction Stir Welded Plate; Influence of the Mechanical Loading on the Residual Stress Distribution

    NASA Astrophysics Data System (ADS)

    Paun, Florin; Azouzi, Alexandre

    2004-06-01

    The Friction Stir Welding is considered to be one of the most promising processing for aeronautics. The obtained welded joints (for the best welding parameters) seem to have better resistance than conventional joining techniques including riveting. To predict the best welding process conditions, current work aims to completely describe the thermo-mechanical history using computer simulation. In this paper, we will present the latest numerical results, thermal and stress-strain fields, obtained for a "virtual" welded plate. This numerical simulation introduces both thermal and mechanical loadings using a step by step advancing coupled method with SAMCEF code. Further works are proposed for the development of a FSW predictive numerical tool.

  14. The Thermo-Mechanical Problem of Internal and Edge Cracks in Multi-Layered Woven GFRP Laminates at Cryogenic Temperatures

    NASA Astrophysics Data System (ADS)

    Takeda, T.; Shindo, Y.; Narita, F.

    2004-06-01

    This paper presents the thermo-mechanical response of multi-layered G-11 woven glass/epoxy laminates with internal and/or edge cracks under tensile loading at cryogenic temperatures obtained from a two-dimensional finite element analysis. A condition of generalized plane strain is assumed to exist in the composite. Cracks are considered to occur in the transverse fiber bundles and extend through the entire thickness of the fiber bundles. The finite element model accounts for the temperature-dependent constituent properties. A detailed examination of the Young's modulus and stress distributions near the crack tip is carried out which provides insight into material behavior at cryogenic temperatures.

  15. Nanocomposites of polymers with layered inorganic nanofillers: Antimicrobial activity, thermo-mechanical properties, morphology, and dispersion

    NASA Astrophysics Data System (ADS)

    Songtipya, Ponusa

    's characteristics to the thermo-mechanical properties of their nanocomposites was systematically explored. The appropriate compatibilizer, based on HDPE-g-MA, was identified from achieving the best mechanical performance, i.e., maximizing the tensile modulus improvement without sacrificing the polymer ductility, which was found to be achieved where the smallest crystallinity change occured. It was revealed that lower-than-the matrix molecular weight HDPE-g-MA better enhanced the tensile properties across three HDPEs, compared to that of high viscosity HDPE-g-MA, while the flexural properties were not markedly affected by this parameter, but rather were mostly determined by the amount of clay nanofiller. Finally, polymer/layered double hydroxide (LDH, positively-charged layered clays, also termed as 'anionic' clays referring to their anion exchange capacity) were characterized as potential fillers for a variety of polymer matrices. The main focus in this part of the research was on the morphology and dispersion of the LDH as it related to their composition and their organic modification in relation to the nature of various polymers. Exemplary polymer matrices that span the range from non-polar to polar interactions---including Polypropylene (PP), polyethylenes (PE, and PE-copolymers), polymethyl-methacrylate (PMMA), polystyrene (PS)---were explored. It was observed that the LDH composition, organic modification, and polymer types were the parameters which controlled the LDH structure and dispersion, albeit in a rather involved fashion.

  16. Influence of thermo-mechanical treatment on the tensile properties of a modified 14Cr-15Ni stainless steel

    NASA Astrophysics Data System (ADS)

    Vijayanand, V. D.; Laha, K.; Parameswaran, P.; Nandagopal, M.; Panneer Selvi, S.; Mathew, M. D.

    2014-10-01

    The titanium modified 14Cr-15Ni austenitic stainless steel is used as clad and wrapper material for fast breeder nuclear reactor. Thermo-mechanical treatments consisting of solution annealing at two different temperatures of 1273 and 1373 K followed by cold-work and thermal ageing have been imparted to the steel to tailor its microstructure for enhancing strength. Tensile tests have been carried out on the thermo-mechanically treated steel at nominal strain rate of 1.6 × 10-4 s-1 over a temperature range of 298-1073 K. The yield stress and the ultimate tensile strength of the steel increased with increase in solution treatment temperature and this has been attributed to the fine and higher density of Ti(C,N) precipitate. Tensile flow behaviour of the steel has been analysed using Ludwigson and Voce constitutive equations. The steel heat treated at higher solution temperature exhibited earlier onset of cross slip during tensile deformation. The rate of recovery at higher test temperatures was also influenced by variations in solution heat treatment temperature. In addition, dynamic recrystallization during tensile deformation at higher temperatures was profound for steel solution heat-treated at lower temperature. The differences in flow behaviour and softening mechanisms during tensile testing of the steel after different heat treated conditions have been attributed to the nature of Ti(C,N) precipitation.

  17. Effect of thermo-mechanical treatments on the microstructure and mechanical properties of an ODS ferritic steel

    NASA Astrophysics Data System (ADS)

    Oksiuta, Z.; Mueller, P.; Spätig, P.; Baluc, N.

    2011-05-01

    The Fe-14Cr-2W-0.3Ti-0.3Y 2O 3 oxide dispersion strengthened (ODS) reduced activation ferritic (RAF) steel was fabricated by mechanical alloying of a pre-alloyed, gas atomised powder with yttria nano-particles, followed by hot isostatic pressing and thermo-mechanical treatments (TMTs). Two kinds of TMT were applied: (i) hot pressing, or (ii) hot rolling, both followed by annealing in vacuum at 850 °C. The use of a thermo-mechanical treatment was found to yield strong improvement in the microstructure and mechanical properties of the ODS RAF steel. In particular, hot pressing leads to microstructure refinement, equiaxed grains without texture, and an improvement in Charpy impact properties, especially in terms of the upper shelf energy (about 4.5 J). Hot rolling leads to elongated grains in the rolling direction, with a grain size ratio of 6:1, higher tensile strength and reasonable ductility up to 750 °C, and better Charpy impact properties, especially in terms of the ductile-to-brittle transition temperature (about 55 °C).

  18. Proof-of-concept switchable hydrophobic/hydrophilic patterned surfaces from thermo-mechanically tailored acrylate systems

    NASA Astrophysics Data System (ADS)

    Laursen, Christopher M.

    A novel, proof-of-concept, switchable hydrophobic/hydrophilic structured surface targeted to assist in antifouling of materials in aqueous environments was created through the development of a multi-tiered platform. The understructure consists of a thermo-mechanically tailored acrylate based polymer patterned in a pillared array, which was then overlaid with spatially tailored hydrophobic/hydrophilic surface chemistry treatments. Development focused on the synthesis of a ternary acrylate system displaying proper thermo-mechanical behavior in submerged conditions for the understructure, creation of a sufficient soft molding technique, and methods to chemically alter water-surface wetting interactions. The final acrylate based polymer constituents were chosen based on expected low-toxicity and the ability to be photopolymerized, while the final system displayed appropriate mechanical toughness, water absorption, and material stiffness over a select temperature window. This was important as alteration in wettability characteristics relied upon a stark transition in the polymeric materials stiffness within a narrow temperature range. The material qualitatively displayed a more hydrophobic state with the pillared surface structures erect, and a more hydrophilic state with the pillars bent over.

  19. Toward Improving the Type IV Cracking Resistance in Cr-Mo Steel Weld Through Thermo-Mechanical Processing

    DOE PAGESBeta

    Shassere, Benjamin A.; Yamamoto, Yukinori; Babu, Sudarsanam Suresh

    2016-02-23

    Detailed microstructure characterization of Grade 91 (Modified 9Cr-1Mo, ASTM A387) steel subjected to a thermo-mechanical treatment (TMT) process was performed to rationalize the cross-weld creep properties. A series of thermo-mechanical processing in the austenite phase region, followed by isothermal aging at temperatures at 973 to 1173 K (700 to 900ºC) was applied to the Grade 91 steel to promote precipitation kinetics of MX (M: Nb and V, X: C and N) in the austenite matrix. Detailed characterization of the base metals after standard tempering confirmed the presence of fine MX dispersion within the tempered martensitic microstructure in steels processed at/andmore » above 1073 K (800 ºC). Relatively low volume fraction of M23C6 precipitates was observed after processing at 1073 K (800 ºC). The cross-weld creep strength after processing was increased with respect to the increase of MX dispersion, indicating that these MX precipitates maintained during weld thermal cycles in the fine grained heat affected zone (FGHAZ) region and thereby contribute to improved creep resistant of welds in comparison to the welds made with the standard “normalization and tempering” processes. Lastly, the steels processed in this specific processing condition showed improved cross-weld creep resistance and sufficient room-temperature toughness. The above data is also analysed based on existing theories of creep deformation based on dislocation climb mechanism.« less

  20. Thermo-mechanical fatigue behavior of the intermetallic gamma-TiAl alloy TNB-V5 with different microstructures

    NASA Astrophysics Data System (ADS)

    Roth, M.; Biermann, H.

    2010-07-01

    The cyclic deformation and fatigue behavior of the γ-TiAl alloy TNB-V5 is studied under thermo-mechanical load for the three technically important microstructures Fully-Lamellar (FL), Near-Gamma (NG) and Duplex (DP), respectively. Thus, thermo-mechanical fatigue (TMF) tests were carried out with different temperature-strain cycles, different temperature ranges from 400°C to 800°C and with two different strain ranges. Cyclic deformation curves, stress-strain hysteresis loops and fatigue lives are presented. The type of microstructure shows a surprisingly small influence on the cyclic deformation and fatigue behavior under TMF conditions. For a general life prediction the damage parameter of Smith, Watson and Topper PSWT is well suitable, if the testing and the application temperature ranges, respectively, include temperatures above the ductile-brittle transition temperature (approx. 750°C). If the maximum temperature is below that temperature, the brittle materials' behavior yields a high scatter of fatigue lives and a low slope of the fatigue life curve and therefore the damage parameter PSWT cannot be applied for the live prediction.

  1. Microstructure Evolution of a Platinum-Modified Nickel-Aluminide Coating During Thermal and Thermo-mechanical Fatigue

    NASA Astrophysics Data System (ADS)

    Sallot, Pierre; Maurel, Vincent; Rémy, Luc; N'Guyen, Franck; Longuet, Arnaud

    2015-10-01

    The microstructure evolution of a platinum-modified nickel-aluminide coating on single-crystal nickel-based superalloy was investigated for various thermal cycling and thermo-mechanical fatigue (TMF) conditions in air for a long-term exposure. An increase in roughness and in β→γ' transformation rate depends similarly on maximum temperature, holding time at maximum temperature and applied stress. Moreover, the evolution of the interdiffusion zone (IDZ) is analyzed by making the distinction between two layers, according to the major phases observed within these layers, namely β-(Ni,Pt)Al and γ'-Ni3Al. This distinction highlighted that the respective thickness evolution of these two layers are sensitive to each parameter of TMF tests with similar increase in evolution rate when increasing time, temperature, as well as applied stress. The distinctive features of phase transformation are finally discussed together with localization of phase transformation and measured evolution of phase transformation within the external coating and β- and γ'-IDZ layer thicknesses under thermal and thermo-mechanical fatigue. This analysis leads to a conclusion that grain boundaries within the external coating as well as interfaces, between thermally grown oxide, external coating, and IDZ, respectively, play a major role in diffusion, phase transformation, and microstructure evolution of typical platinum-modified nickel-aluminide coating.

  2. Influence of Different Thermo-mechanical Cycling Routes on Recovery Stresses of Annealed NiTi Wires

    NASA Astrophysics Data System (ADS)

    Yan, X. J.; Ge, Y. L.; Van Humbeeck, J.

    2016-01-01

    In this study, the influence of different thermo-mechanical cycling routes on recovery stresses of annealed NiTi wires has been investigated by using a dynamic mechanical analyzer. The as-received wire was annealed in Argon atmosphere in the temperature range of 350 to 900 °C. Differential scanning calorimeter was used to study the martensite transformation. In route I, the sample is deformed to 2% pre-strain and recovery stress is measured after unloading. In route II, the sample undergoes 3% deformation followed by a free shape recovery and then is reloaded to 2% pre-strain and recovery stress is measured after unloading. In route III, the sample undergoes a constrained thermal cycling at 3% pre-strain followed by a free shape recovery and then recovery stress is measured at 2% pre-strain. The results show that both route II and III can improve the recovery stresses. Route III has higher recovery stresses than route II for samples annealed at 550-700 °C. The improvements of recovery stresses under route II and III are partly attributed to the decrease of A s temperatures after thermo-mechanical cycling. Such information is essential for the proper use of NiTi alloys in smart structures, intelligent controllers, and memory devices.

  3. On the Effects of Thermal History on the Development and Relaxation of Thermo-Mechanical Stress in Cryopreservation

    PubMed Central

    Eisenberg, David P.; Steif, Paul S.; Rabin, Yoed

    2014-01-01

    This study investigates the effects of the thermal protocol on the development and relaxation of thermo-mechanical stress in cryopreservation by means of glass formation, also known as vitrification. The cryopreserved medium is modeled as a homogeneous viscoelastic domain, constrained within either a stiff cylindrical container or a highly compliant bag. Annealing effects during the cooling phase of the cryopreservation protocol are analyzed. Results demonstrate that an intermediate temperature-hold period can significantly reduce the maximum tensile stress, thereby decreasing the potential for structural damage. It is also demonstrated that annealing at temperatures close to glass transition significantly weakens the dependency of thermo-mechanical stress on the cooling rate. Furthermore, a slower initial rewarming rate after cryogenic storage may drastically reduce the maximum tensile stress in the material, which supports previous experimental observations on the likelihood of fracture at this stage. This study discusses the dependency of the various stress components on the storage temperature. Finally, it is demonstrated that the stiffness of the container wall can affect the location of maximum stress, with implications on the development of cryopreservation protocols. PMID:25792762

  4. Predicting thermo-mechanical behaviour of high minor actinide content composite oxide fuel in a dedicated transmutation facility

    NASA Astrophysics Data System (ADS)

    Lemehov, S. E.; Sobolev, V. P.; Verwerft, M.

    2011-09-01

    The European Facility for Industrial Transmutation (EFIT) of the minor actinides (MA), from LWR spent fuel is being developed in the integrated project EUROTRANS within the 6th Framework Program of EURATOM. Two composite uranium-free fuel systems, containing a large fraction of MA, are proposed as the main candidates: a CERCER with magnesia matrix hosting (Pu,MA)O 2-x particles, and a CERMET with metallic molybdenum matrix. The long-term thermal and mechanical behaviour of the fuel under the expected EFIT operating conditions is one of the critical issues in the core design. To make a reliable prediction of long-term thermo-mechanical behaviour of the hottest fuel rods in the lead-cooled version of EFIT with thermal power of 400 MW, different fuel performance codes have been used. This study describes the main results of modelling the thermo-mechanical behaviour of the hottest CERCER fuel rods with the fuel performance code MACROS which indicate that the CERCER fuel residence time can safely reach at least 4-5 effective full power years.

  5. Toward Improving the Type IV Cracking Resistance in Cr-Mo Steel Weld Through Thermo-Mechanical Processing

    NASA Astrophysics Data System (ADS)

    Shassere, Benjamin A.; Yamamoto, Yukinori; Babu, Sudarsanam Suresh

    2016-05-01

    Detailed microstructure characterization of Grade 91 (Modified 9Cr-1Mo, ASTM A387) steel subjected to a thermo-mechanical treatment process was performed to rationalize the cross-weld creep properties. A series of thermo-mechanical processing in the austenite phase region, followed by isothermal aging at temperatures at 973 K to 1173 K (700 °C to 900 °C), was applied to the Grade 91 steel to promote precipitation kinetics of MX (M: Nb and V, X: C and N) in the austenite matrix. Detailed characterization of the base metals after standard tempering confirmed the presence of fine MX dispersion within the tempered martensitic microstructure in steels processed at/and above 1073 K (800 °C). Relatively low volume fraction of M23C6 precipitates was observed after processing at 1073 K (800 °C). The cross-weld creep strength after processing was increased with respect to the increase of MX dispersion, indicating that these MX precipitates maintained during weld thermal cycles in the fine-grained heat-affected zone region and thereby contribute to improved creep resistant of welds in comparison to the welds made with the standard "normalization and tempering" processes. The steels processed in this specific processing condition showed improved cross-weld creep resistance and sufficient room temperature toughness. The above data are also analyzed based on existing theories of creep deformation based on dislocation climb mechanism.

  6. On the effects of thermal history on the development and relaxation of thermo-mechanical stress in cryopreservation

    NASA Astrophysics Data System (ADS)

    Eisenberg, David P.; Steif, Paul S.; Rabin, Yoed

    2014-11-01

    This study investigates the effects of the thermal protocol on the development and relaxation of thermo-mechanical stress in cryopreservation by means of glass formation, also known as vitrification. The cryopreserved medium is modeled as a homogeneous viscoelastic domain, constrained within either a stiff cylindrical container or a highly compliant bag. Annealing effects during the cooling phase of the cryopreservation protocol are analyzed. Results demonstrate that an intermediate temperature-hold period can significantly reduce the maximum tensile stress, thereby decreasing the potential for structural damage. It is also demonstrated that annealing at temperatures close to glass transition significantly weakens the dependency of thermo-mechanical stress on the cooling rate. Furthermore, a slower initial rewarming rate after cryogenic storage may drastically reduce the maximum tensile stress in the material, which supports previous experimental observations on the likelihood of fracture at this stage. This study discusses the dependency of the various stress components on the storage temperature. Finally, it is demonstrated that the stiffness of the container wall can affect the location of maximum stress, with implications on the development of cryopreservation protocols.

  7. Power subsystem automation study

    NASA Technical Reports Server (NTRS)

    Tietz, J. C.; Sewy, D.; Pickering, C.; Sauers, R.

    1984-01-01

    The purpose of the phase 2 of the power subsystem automation study was to demonstrate the feasibility of using computer software to manage an aspect of the electrical power subsystem on a space station. The state of the art in expert systems software was investigated in this study. This effort resulted in the demonstration of prototype expert system software for managing one aspect of a simulated space station power subsystem.

  8. Minimal noise subsystems

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoting; Byrd, Mark; Jacobs, Kurt

    2016-03-01

    A system subjected to noise contains a decoherence-free subspace or subsystem (DFS) only if the noise possesses an exact symmetry. Here we consider noise models in which a perturbation breaks a symmetry of the noise, so that if S is a DFS under a given noise process it is no longer so under the new perturbed noise process. We ask whether there is a subspace or subsystem that is more robust to the perturbed noise than S . To answer this question we develop a numerical method that allows us to search for subspaces or subsystems that are maximally robust to arbitrary noise processes. We apply this method to a number of examples, and find that a subsystem that is a DFS is often not the subsystem that experiences minimal noise when the symmetry of the noise is broken by a perturbation. We discuss which classes of noise have this property.

  9. Regional-scale geomechanical impact assessment of underground coal gasification by coupled 3D thermo-mechanical modeling

    NASA Astrophysics Data System (ADS)

    Otto, Christopher; Kempka, Thomas; Kapusta, Krzysztof; Stańczyk, Krzysztof

    2016-04-01

    Underground coal gasification (UCG) has the potential to increase the world-wide coal reserves by utilization of coal deposits not mineable by conventional methods. The UCG process involves combusting coal in situ to produce a high-calorific synthesis gas, which can be applied for electricity generation or chemical feedstock production. Apart from its high economic potentials, UCG may induce site-specific environmental impacts such as fault reactivation, induced seismicity and ground subsidence, potentially inducing groundwater pollution. Changes overburden hydraulic conductivity resulting from thermo-mechanical effects may introduce migration pathways for UCG contaminants. Due to the financial efforts associated with UCG field trials, numerical modeling has been an important methodology to study coupled processes considering UCG performance. Almost all previous UCG studies applied 1D or 2D models for that purpose, that do not allow to predict the performance of a commercial-scale UCG operation. Considering our previous findings, demonstrating that far-field models can be run at a higher computational efficiency by using temperature-independent thermo-mechanical parameters, representative coupled simulations based on complex 3D regional-scale models were employed in the present study. For that purpose, a coupled thermo-mechanical 3D model has been developed to investigate the environmental impacts of UCG based on a regional-scale of the Polish Wieczorek mine located in the Upper Silesian Coal Basin. The model size is 10 km × 10 km × 5 km with ten dipping lithological layers, a double fault and 25 UCG reactors. Six different numerical simulation scenarios were investigated, considering the transpressive stress regime present in that part of the Upper Silesian Coal Basin. Our simulation results demonstrate that the minimum distance between the UCG reactors is about the six-fold of the coal seam thickness to avoid hydraulic communication between the single UCG

  10. Influence of the selenium content on thermo-mechanical and optical properties of Ge-Ga-Sb-S chalcogenide glasses

    NASA Astrophysics Data System (ADS)

    Ye, Bin; Dai, Shixun; Wang, Rongping; Tao, Guangming; Zhang, Peiqing; Wang, Xunsi; Shen, Xiang

    2016-07-01

    A number of Ge17Ga4Sb10S69-xSex (x = 0, 15, 30, 45, 60, and 69) chalcogenide glasses have been synthesized by a melt-quenching method to investigate the effect of the Se content on thermo-mechanical and optical properties of these glasses. While it was found that the glass transition temperature (Tg) decreases from 261 to 174 °C with increasing Se contents, crystallization temperature (Tc) peak only be observed in glasses with Se content of x = 45. It was evident from the measurements of structural and physical properties that changes of the glass network bring an apparent impact on the glass properties. Also, the substitution of Se for S in Ge-Ga-Sb glasses can significantly improve the thermal stability against crystallization and broaden the infrared transmission region.

  11. New thermo-mechanical fluid flow modeling of multiscale deformations in the Levant basin: formulation, verification, and preliminary analysis

    NASA Astrophysics Data System (ADS)

    Belferman, Mariana; Katsman, Regina; Agnon, Amotz

    2015-04-01

    The Levant has been repeatedly devastated by numerous earthquakes since prehistorical time, as recorded in historical documents, archaeological ruins, and sedimentary archives. In order to understand the role of the dynamics of the water bodies in triggering the deformations in the Levant basin, a new theoretical thermo-mechanical model is constructed and extended by including a fluid flow component. The latter is modeled on a basis of two-way poroelastic coupling with momentum equation. This coupling is essential to capture the fluid flow evolution induced by dynamic water loading and to resolve porosity changes. All the components of the model, namely elasticity, creep, plasticity, fluid flow, etc., have been extensively verified and presented. Results of the initial sensitivity analysis addressing the relative importance of each process in earthquakes triggering are discussed. The rich archives of pre-instrumental destructive earthquakes will set constraints for future modeling under the present formulation.

  12. Experimental study of thermo-mechanical behavior of SiC composite tubing under high temperature gradient using solid surrogate

    NASA Astrophysics Data System (ADS)

    Alva, Luis; Shapovalov, Kirill; Jacobsen, George M.; Back, Christina A.; Huang, Xinyu

    2015-11-01

    Nuclear grade silicon carbide fiber (SiCf) reinforced silicon carbide matrix (SiCm) composite is a promising candidate material for accident tolerance fuel (ATF) cladding. A major challenge is ensuring the mechanical robustness of the ceramic cladding under accident conditions. In this work the high temperature mechanical response of a SiCf-SiCm composite tubing is studied using a novel thermo-mechanical test method. A solid surrogate tube is placed within and bonded to the SiCf-SiCm sample tube using a ceramic adhesive. The bonded tube pair is heated from the center using a ceramic glower. During testing, the outer surface temperature of the SiC sample tube rises up to 1274 K, and a steep temperature gradient develops through the thickness of the tube pair. Due to CTE mismatch and the temperature gradient, the solid surrogate tube induces high tensile stress in the SiC sample. During testing, 3D digital image correlation (DIC) method is used to map the strains on the outer surface of the SiC-composite, and acoustic emissions (AE) are monitored to detect the onset and progress of material damage. The thermo-mechanical behavior of SiC-composite sample is compared with that of monolithic SiC samples. Finite element models are developed to estimate stress-strain distribution within the tube assembly. Model predicted surface strain matches the measured surface strain using the DIC method. AE activities indicated a progressive damage process for SiCf-SiCm composite samples. For the composites tested in this study, the threshold mechanical hoop strain for matrix micro-cracking to initiate in SiCf-SiCm sample is found to be ∼300 microstrain.

  13. Experimental study of thermo-mechanical behavior of SiC composite tubing under high temperature gradient using solid surrogate

    NASA Astrophysics Data System (ADS)

    Alva, Luis; Shapovalov, Kirill; Jacobsen, George M.; Back, Christina A.; Huang, Xinyu

    2015-11-01

    Nuclear grade silicon carbide fiber (SiCf) reinforced silicon carbide matrix (SiCm) composite is a promising candidate material for accident tolerance fuel (ATF) cladding. A major challenge is ensuring the mechanical robustness of the ceramic cladding under accident conditions. In this work the high temperature mechanical response of a SiCf-SiCm composite tubing is studied using a novel thermo-mechanical test method. A solid surrogate tube is placed within and bonded to the SiCf-SiCm sample tube using a ceramic adhesive. The bonded tube pair is heated from the center using a ceramic glower. During testing, the outer surface temperature of the SiC sample tube rises up to 1274 K, and a steep temperature gradient develops through the thickness of the tube pair. Due to CTE mismatch and the temperature gradient, the solid surrogate tube induces high tensile stress in the SiC sample. During testing, 3D digital image correlation (DIC) method is used to map the strains on the outer surface of the SiC-composite, and acoustic emissions (AE) are monitored to detect the onset and progress of material damage. The thermo-mechanical behavior of SiC-composite sample is compared with that of monolithic SiC samples. Finite element models are developed to estimate stress-strain distribution within the tube assembly. Model predicted surface strain matches the measured surface strain using the DIC method. AE activities indicated a progressive damage process for SiCf-SiCm composite samples. For the composites tested in this study, the threshold mechanical hoop strain for matrix micro-cracking to initiate in SiCf-SiCm sample is found to be ˜300 microstrain.

  14. The effects of short-lived radionuclides and porosity on the early thermo-mechanical evolution of planetesimals

    NASA Astrophysics Data System (ADS)

    Lichtenberg, Tim; Golabek, Gregor J.; Gerya, Taras V.; Meyer, Michael R.

    2016-08-01

    The thermal history and internal structure of chondritic planetesimals, assembled before the giant impact phase of chaotic growth, potentially yield important implications for the final composition and evolution of terrestrial planets. These parameters critically depend on the internal balance of heating versus cooling, which is mostly determined by the presence of short-lived radionuclides (SLRs), such as 26Al and 60Fe, as well as the heat conductivity of the material. The heating by SLRs depends on their initial abundances, the formation time of the planetesimal and its size. It has been argued that the cooling history is determined by the porosity of the granular material, which undergoes dramatic changes via compaction processes and tends to decrease with time. In this study we assess the influence of these parameters on the thermo-mechanical evolution of young planetesimals with both 2D and 3D simulations. Using the code family I2ELVIS/I3ELVIS we have run numerous 2D and 3D numerical finite-difference fluid dynamic models with varying planetesimal radius, formation time and initial porosity. Our results indicate that powdery materials lowered the threshold for melting and convection in planetesimals, depending on the amount of SLRs present. A subset of planetesimals retained a powdery surface layer which lowered the thermal conductivity and hindered cooling. The effect of initial porosity was small, however, compared to those of planetesimal size and formation time, which dominated the thermo-mechanical evolution and were the primary factors for the onset of melting and differentiation. We comment on the implications of this work concerning the structure and evolution of these planetesimals, as well as their behavior as possible building blocks of terrestrial planets.

  15. IO SUBSYSTEM 1 BETA

    SciTech Connect

    Sjaardema, Greg

    2002-08-21

    "IO Subsystem Ver. 1.0 Beta" uses standard object-oriented principles to minimize dependencies between the underlying input or output database format and the client code (i.e., Sierra) using the io subsystem. The interface and priciples are simolar to the Facade pattern described in the "Design Patterns" book by Gamma, et.al. The software uses data authentication algorithms to ensure data input/output is consistent with model being defined. "IO Subsystem Ver. 1.0 Beta" is a database independent input/output library for finite element analysis, preprocessing, post processing, and translation programs.

  16. IO SUBSYSTEM 1 BETA

    2002-08-21

    "IO Subsystem Ver. 1.0 Beta" uses standard object-oriented principles to minimize dependencies between the underlying input or output database format and the client code (i.e., Sierra) using the io subsystem. The interface and priciples are simolar to the Facade pattern described in the "Design Patterns" book by Gamma, et.al. The software uses data authentication algorithms to ensure data input/output is consistent with model being defined. "IO Subsystem Ver. 1.0 Beta" is a database independent input/outputmore » library for finite element analysis, preprocessing, post processing, and translation programs.« less

  17. Facile preparation of a novel high performance benzoxazine-CNT based nano-hybrid network exhibiting outstanding thermo-mechanical properties.

    PubMed

    Dumas, Ludovic; Bonnaud, Leïla; Olivier, Marjorie; Poorteman, Marc; Dubois, Philippe

    2013-10-25

    Untreated multi-walled carbon nanotubes (MWCNTs) have been dispersed in two benzoxazine precursors following an easy procedure. The strong intrinsic interactions of CNTs with a selected precursor give rise to the formation of a reinforced network with outstanding thermo-mechanical properties. PMID:23963525

  18. Validating predictions made by a thermo-mechanical model of melt segregation in sub-volcanic systems

    NASA Astrophysics Data System (ADS)

    Roele, Katarina; Jackson, Matthew; Morgan, Joanna

    2014-05-01

    A quantitative understanding of the spatial and temporal evolution of melt distribution in the crust is crucial in providing insights into the development of sub-volcanic crustal stratigraphy and composition. This work aims to relate numerical models that describe the base of volcanic systems with geophysical observations. Recent modelling has shown that the repetitive emplacement of mantle-derived basaltic sills, at the base of the lower crust, acts as a heat source for anatectic melt generation, buoyancy-driven melt segregation and mobilisation. These processes form the lowermost architecture of complex sub-volcanic networks as upward migrating melt produces high melt fraction layers. These 'porosity waves' are separated by zones with high compaction rates and have distinctive polybaric chemical signatures that suggest mixed crust and mantle origins. A thermo-mechanical model produced by Solano et al in 2012 has been used to predict the temperatures and melt fractions of successive high porosity layers within the crust. This model was used as it accounts for the dynamic evolution of melt during segregation and migration through the crust; a significant process that has been neglected in previous models. The results were used to input starting compositions for each of the layers into the rhyolite-MELTS thermodynamic simulation. MELTS then determined the approximate bulk composition of the layers once they had cooled and solidified. The mean seismic wave velocities of the polymineralic layers were then calculated using the relevant Voight-Reuss-Hill mixture rules, whilst accounting for the pressure and temperature dependence of seismic wave velocity. The predicted results were then compared with real examples of reflectivity for areas including the UK, where lower crustal layering is observed. A comparison between the impedance contrasts at compositional boundaries is presented as it confirms the extent to which modelling is able to make predictions that are

  19. Power subsystem automation study

    NASA Technical Reports Server (NTRS)

    Imamura, M. S.; Moser, R. L.; Veatch, M.

    1983-01-01

    Generic power-system elements and their potential faults are identified. Automation functions and their resulting benefits are defined and automation functions between power subsystem, central spacecraft computer, and ground flight-support personnel are partitioned. All automation activities were categorized as data handling, monitoring, routine control, fault handling, planning and operations, or anomaly handling. Incorporation of all these classes of tasks, except for anomaly handling, in power subsystem hardware and software was concluded to be mandatory to meet the design and operational requirements of the space station. The key drivers are long mission lifetime, modular growth, high-performance flexibility, a need to accommodate different electrical user-load equipment, onorbit assembly/maintenance/servicing, and potentially large number of power subsystem components. A significant effort in algorithm development and validation is essential in meeting the 1987 technology readiness date for the space station.

  20. Development and implementation of CAE system HEARTS for heat treatment simulation based on metallo-thermo-mechanics

    SciTech Connect

    Inoue, T.; Arimoto, K.

    1997-02-01

    Based on the framework of metallo-thermo-mechanics proposed by the authors, a CAE system, HEARTS (HEAt tReaTment Simulation system), has been developed to simulate metallic structure, temperature, and stress/strain in the heat treatment processes associated with phase transformation, such as quenching and tempering by means of the finite element method. In the first part of the paper, the governing theory is introduced; fundamental equations of metallurgical change due to phase transformation, heat conduction, and stress analysis are presented; and the effect of coupling among these three fields is discussed. the development strategy, methodology, structure, and directions for use of the HEARTS system are stated in the following sections. Simulated results on temperature, structural change, and stress/strain, as well as carbon content during the heat treatment process, are illustrated for engineering components in two- and three-dimensional shape and a Japanese sword by use of the system combined with a pre-/post-processor. The validity of the system is evaluated by comparison with the experimental data.

  1. Thermo-mechanical and optical analysis and modeling for a diamond-cooled solid-state Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Chou, Hsian P.; Sadovnik, Isaac; Tammaro, Eric J.; Wang, Yu-Lin; Bass, Michael; Chen, Ying

    2006-05-01

    In 2000, Textron Systems Corporation (TSC) initiated the development of an advanced diamond cooled solid-state laser concept suitable for ultra compact medium and high-power lasers. The resulting laser configuration is applicable to laser diode pumping and a wide variety of lasing materials. In order to further improve the performance and determine the limitation of this laser concept, the detailed physical understanding of the interface between diamond and YAG disks was identified as a critical issue. Numerical analyses had been conducted for investigating the thermal-mechanical interaction in the interface between the gain medium and the diamond disks when the lasing process is in progress. Following this analyses, a computer model has been developed to simulate the phenomena of light interaction with the active medium. Subsequently, this computer model has been applied to optimize the laser design, in which the performance in terms of efficiency and compactness for a diamond-cooled laser has shown significant improvements. The understanding of the thermo-mechanical/optical issues at the interface, in general, will be beneficial to a variety of solid-state laser design activities.

  2. Fracture Mechanics Analyses of Subsurface Defects in Reinforced Carbon-Carbon Joggles Subjected to Thermo-Mechanical Loads

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Raju, Ivatury S.; Song, Kyongchan

    2011-01-01

    Coating spallation events have been observed along the slip-side joggle region of the Space Shuttle Orbiter wing-leading-edge panels. One potential contributor to the spallation event is a pressure build up within subsurface voids or defects due to volatiles or water vapor entrapped during fabrication, refurbishment, or normal operational use. The influence of entrapped pressure on the thermo-mechanical fracture-mechanics response of reinforced carbon-carbon with subsurface defects is studied. Plane-strain simulations with embedded subsurface defects are performed to characterize the fracture mechanics response for a given defect length when subjected to combined elevated-temperature and subsurface-defect pressure loadings to simulate the unvented defect condition. Various subsurface defect locations of a fixed-length substrate defect are examined for elevated temperature conditions. Fracture mechanics results suggest that entrapped pressure combined with local elevated temperatures have the potential to cause subsurface defect growth and possibly contribute to further material separation or even spallation. For this anomaly to occur, several unusual circumstances would be required making such an outcome unlikely but plausible.

  3. Thermo-Mechanical Properties of SiC/SiC Composites with Hybrid CVI-PIP Matrices

    NASA Technical Reports Server (NTRS)

    Bhatt, R. T.; DiCarlo, J. A.

    2004-01-01

    For long term structural service, the upper temperature capability for slurry-cast melt infiltrated (MI) SiC/SiC composites is limited to approx. 1315 C because of silicon reaction with the SiC fibers. For applications requiring material temperatures in excess of 1315 C, alternate methods of manufacturing the SiC matrices without silicon are being investigated, such as a hybrid combination of CVI and PIP. In this study, stacked fabric plies of Sylramic i-BN SiC fibers were coated with a CVI BN interface layer followed by a partial CVI SiC matrix. The remaining porosity in the SiC/SiC preforms was then infiltrated with silicon carbide matrix by PIP. Thermo-mechanical property measurements indicate that these composites are stable to 1700 C in inert environments under no load conditions for 100 h and under load conditions to 1450 C in air for 300 h. The advantages, disadvantages, and potential of this composite system for high temperature applications will be discussed.

  4. Surface and thermal enhancement of the cellulosic component of thermo mechanical pulp using a rapid method: Iodomethane modification.

    PubMed

    George, Michael; Mussone, Paolo G; Bressler, David C

    2016-05-20

    The feasibility of employing chemical methods for enhancement of cellulose-based materials is dependent on the availability, price, and green index of the modifying agent. This study details the use of iodomethane, an inexpensive organo halide, to increase the hydrophobicity of thermo mechanical (TMP) samples, which renders them better structural elements for composite materials. For this system, we studied the influence of various concentration of iodomethane, concentration of caustic, and reaction time. Infrared spectroscopy suggested reaction of the organo halide with the hydroxyl groups of cellulose and lignin components of TMP. Pulp samples treated for 4 h or at low caustic concentration showed the least improvements plausibly due to pulp degradation or poor pulp swelling, respectively. On the other hand, pulp treated at 3 h using high concentrations of caustic were characterized with surfaces that were more hydrophobic. Thus, this study outlines a fast and organic solvent-free (clean up) method that can be used to enhance pulp samples for composite applications. PMID:26917403

  5. Numerical calculation of thermo-mechanical problems at large strains based on complex step derivative approximation of tangent stiffness matrices

    NASA Astrophysics Data System (ADS)

    Balzani, Daniel; Gandhi, Ashutosh; Tanaka, Masato; Schröder, Jörg

    2015-05-01

    In this paper a robust approximation scheme for the numerical calculation of tangent stiffness matrices is presented in the context of nonlinear thermo-mechanical finite element problems and its performance is analyzed. The scheme extends the approach proposed in Kim et al. (Comput Methods Appl Mech Eng 200:403-413, 2011) and Tanaka et al. (Comput Methods Appl Mech Eng 269:454-470, 2014 and bases on applying the complex-step-derivative approximation to the linearizations of the weak forms of the balance of linear momentum and the balance of energy. By incorporating consistent perturbations along the imaginary axis to the displacement as well as thermal degrees of freedom, we demonstrate that numerical tangent stiffness matrices can be obtained with accuracy up to computer precision leading to quadratically converging schemes. The main advantage of this approach is that contrary to the classical forward difference scheme no round-off errors due to floating-point arithmetics exist within the calculation of the tangent stiffness. This enables arbitrarily small perturbation values and therefore leads to robust schemes even when choosing small values. An efficient algorithmic treatment is presented which enables a straightforward implementation of the method in any standard finite-element program. By means of thermo-elastic and thermo-elastoplastic boundary value problems at finite strains the performance of the proposed approach is analyzed.

  6. A thermo-mechanical model for Nb3Sn filaments and wires: strain field for different strand layouts

    NASA Astrophysics Data System (ADS)

    Boso, Daniela P.; Lefik, Marek

    2009-12-01

    In Nb3Sn CIC conductors, the superconducting compound is distributed into fine filaments and embedded in a resistive matrix for electrical and thermal stability. Nb3Sn formation requires a solid state diffusion reaction at high temperature, which causes an Sn gradient inside the filaments. It is well known that the critical parameters vary with composition (Sn content) and strain state. In this work the complete 3D strain field is computed for different wire layouts. First, the relation between the grade of filament reaction and strain is investigated: superconducting wires are studied, taking into consideration non-homogeneous Nb3Sn filaments, i.e. considering an unreacted core of pure Nb. Furthermore, the case when the filaments agglomerate together to give a 'macrofilament' is also taken into consideration (internal tin wires). A finite element discretization fine enough to take into consideration non-homogeneous filaments would result in a very high number of unknowns, which could be beyond the capacity of today's computers. Therefore a thermo-mechanical model is formulated, based on the generalized self-consistent method, suitably developed to deal with the material nonlinearity and the coupling between the thermal and mechanical fields. In this way, equivalent homogeneous properties are obtained and the analysis of the wires becomes feasible. An appropriate unsmearing technique finally gives the strain state in the real, not homogenized, materials.

  7. TRISO-fuel element thermo-mechanical performance modeling for the hybrid LIFE engine with Pu fuel blanket

    NASA Astrophysics Data System (ADS)

    DeMange, P.; Marian, J.; Caro, M.; Caro, A.

    2010-10-01

    A TRISO-coated fuel thermo-mechanical performance study is performed for the fusion-fission hybrid Laser Inertial Fusion Engine (LIFE) to test the viability of TRISO particles to achieve ultra-high burn-up of Pu or transuranic spent nuclear fuel blankets. Our methodology includes full elastic anisotropy, time and temperature varying material properties, and multilayer capabilities. In order to achieve fast fluences up to 30 × 10 25 n m -2 ( E > 0.18 MeV), judicious extrapolations across several orders of magnitude of existing material databases have been carried out. The results of our study indicate that failure of the pyrolytic carbon (PyC) layers occurs within the first 2 years of operation. The particles then behave as a single-SiC-layer particle and the SiC layer maintains reasonably-low tensile stresses until the end-of-life. It is also found that the PyC creep constant, K, has a striking influence on the fuel performance of TRISO-coated particles, whose stresses scale almost inversely proportional to K. Conversely, varying the geometry of the TRISO-coated fuel particles results in little differences in terms of fuel performance.

  8. The Effect of Thermo-mechanical Processing on the Mechanical Properties of Molybdenum-2 Volume%Lanthana

    SciTech Connect

    A.J. Mueller; R.W. Buckman,Jr.; A.J. Shields,Jr

    2001-03-14

    Variations in oxide species and consolidation method have been shown to have a significant effect on the mechanical properties of oxide dispersion strengthened (ODS) molybdenum material. The mechanical behavior of molybdenum - 2 Volume % La[sub]2O[sub]3 mill product forms, produced by a wet doping process, were characterized over the temperature range of -150 degrees C to 1800 degrees C. The various mill product forms evaluated ranged from thin sheet stock to bar stock. Tensile properties of the material in the various product forms were not significantly affected by the vast difference in total cold work. Creep properties, however, were sensitive to the total amount of cold work as well as the starting microstructure. Stress-relieved material had superior creep rupture properties to recrystallized material at 1200 degrees C, while at 1500 degrees C and above the opposite was observed. Thus it is necessary to match the appropriate thermo-mechanical processing and microstructure of molybdenum - 2 volume % LA[sub]2O[sub]3 to the demands of the application being considered.

  9. Numerical modeling of inelastic structures at loading of steady state rolling. Thermo-mechanical asphalt pavement computation

    NASA Astrophysics Data System (ADS)

    Wollny, Ines; Hartung, Felix; Kaliske, Michael

    2016-05-01

    In order to gain a deeper knowledge of the interactions in the coupled tire-pavement-system, e.g. for the future design of durable pavement structures, the paper presents recent results of research in the field of theoretical-numerical asphalt pavement modeling at material and structural level, whereby the focus is on a realistic and numerically efficient computation of pavements under rolling tire load by using the finite element method based on an Arbitrary Lagrangian Eulerian (ALE) formulation. Inelastic material descriptions are included into the ALE frame efficiently by a recently developed unsplit history update procedure. New is also the implementation of a viscoelastic cohesive zone model into the ALE pavement formulation to describe the interaction of the single pavement layers. The viscoelastic cohesive zone model is further extended to account for the normal pressure dependent shear behavior of the bonding layer. Another novelty is that thermo-mechanical effects are taken into account by a coupling of the mechanical ALE pavement computation to a transient thermal computation of the pavement cross-section to obtain the varying temperature distributions of the pavement due to climatic impact. Then, each ALE pavement simulation considers the temperature dependent asphalt material model that includes elastic, viscous and plastic behavior at finite strains and the temperature dependent viscoelastic cohesive zone formulation. The temperature dependent material parameters of the asphalt layers and the interfacial layers are fitted to experimental data. Results of coupled tire-pavement computations are presented to demonstrate potential fields of application.

  10. The deformation and acoustic emission of aluminum-magnesium alloy under non-isothermal thermo-mechanical loading

    SciTech Connect

    Makarov, S. V.; Plotnikov, V. A. Lysikov, M. V.; Kolubaev, E. A.

    2015-10-27

    The following study investigates the deformation behavior and acoustic emission in aluminum-magnesium alloy under conditions of non-isothermal thermo-mechanical loading. The accumulation of deformation in the alloy, in conditions of change from room temperature to 500°C, occurs in two temperature intervals (I, II), characterized by different rates of deformation. The rate of deformation accumulation is correlated with acoustic emission. With load increasing in cycles from 40 to 200 MPa, the value of the boundary temperature (T{sub b}) between intervals I and II changes non-monotonically. In cycles with load up to 90 MPa, the T{sub b} value increases, while an increase up to 200 MPa makes T{sub b} shift toward lower temperatures. This suggests that the shift of boundaries in the region of low temperatures and the appearance of high-amplitude pulses of acoustic emission characterize the decrease of the magnitude of thermal fluctuations with increasing mechanical load, leading to the rupture of interatomic bonds in an elementary deformation act.

  11. Atomic force microscopy applied to the quantification of nano-precipitates in thermo-mechanically treated microalloyed steels

    SciTech Connect

    Renteria-Borja, Luciano; Hurtado-Delgado, Eduardo; Garnica-Gonzalez, Pedro; Dominguez-Lopez, Ivan; Garcia-Garcia, Adrian Luis

    2012-07-15

    Quantification of nanometer-size precipitates in microalloyed steels has been traditionally performed using transmission electron microscopy (TEM), in spite of its complicated sample preparation procedures, prone to preparation errors and sample perturbation. In contrast to TEM procedures, atomic force microscopy (AFM) is performed on the as-prepared specimen, with sample preparation requirements similar to those for optical microscopy (OM), rendering three-dimensional representations of the sample surface with vertical resolution of a fraction of a nanometer. In AFM, contrast mechanisms are directly related to surface properties such as topography, adhesion, and stiffness, among others. Chemical etching was performed using 0.5% nital, at time intervals between 4 and 20 s, in 4 s steps, until reaching the desired surface finish. For the present application, an average surface-roughness peak-height below 200 nm was sought. Quantification results of nanometric precipitates were obtained from the statistical analysis of AFM images of the microstructure developed by microalloyed Nb and V-Mo steels. Topography and phase contrast AFM images were used for quantification. The results obtained using AFM are consistent with similar TEM reports. - Highlights: Black-Right-Pointing-Pointer We quantified nanometric precipitates in Nb and V-Mo microalloyed steels using AFM. Black-Right-Pointing-Pointer Microstructures of the thermo-mechanically treated microalloyed steels were used. Black-Right-Pointing-Pointer Topography and phase contrast AFM images were used for quantification. Black-Right-Pointing-Pointer AFM results are comparable with traditionally obtained TEM measurements.

  12. Microstructure Evolution and Hardness of an Ultra-High Strength Cu-Ni-Si Alloy During Thermo-mechanical Processing

    NASA Astrophysics Data System (ADS)

    Lei, Q.; Li, Z.; Hu, W. P.; Liu, Y.; Meng, C. L.; Derby, B.; Zhang, W.

    2016-07-01

    Microstructure evolution and hardness changes of an ultra-high strength Cu-Ni-Si alloy during thermo-mechanical processing have been investigated. For hot-compressive deformation specimens, dynamic recrystallization preferentially appeared on deformation bands. As deformation temperature increased from 750 to 900 °C, elongated grains with the Cubic texture {001} <100> were substituted by recrystallized grains with Copper texture {112} <111>. For the samples having undergone cold rolling followed by annealing, static recrystallization preferentially occurred in the deformation bands, and then complete recrystallization occurred. Goss, Cubic, and Brass textures remained after annealing at 600 and 700 °C for 1 h; R texture {111} <211> and recrystallization texture {001} <100> were formed in samples annealed at 800 and 900 °C for 1 h, respectively. For samples processed under multi-directional forging at cryogenic temperature, the hardness was increased as a result of work hardening and grain refinement strengthening. These were attributed to the formation of equiaxed sub-grain structures and a high dislocation density.

  13. The role of lateral lithospheric strength heterogeneities in orogenic plateau growth: Insights from 3-D thermo-mechanical modeling

    NASA Astrophysics Data System (ADS)

    Chen, Lin; Gerya, Taras V.

    2016-04-01

    Preexisting lateral variations in crustal thickness and lithospheric thermal state are documented for the formation of some orogenic plateaux. Here we use high-resolution 3-D thermo-mechanical simulations to investigate the influence of preexisting lateral lithospheric strength heterogeneity on the growth of orogenic plateau. The modeling results illustrate an episodic scenario for plateau growth: (1) an early rapid growth stage, characterized by rapid surface uplift and intensive crustal buckling and thickening; (2) an outward spreading stage, characterized by significant lateral expansion of the plateau edges; and (3) a mature stage, characterized by the development of the intracrustal partial melting and subduction of the surrounding lithosphere under the plateau. Sensitivity analyses indicate that lateral variation in crustal thickness favors outward spreading of orogenic plateau, while lateral variation in geothermal gradient favors crustal buckling. The model in absence of lateral strength heterogeneity leads to progressive migration of orogenic belt. Our models show that the plateau's lower crust is largely coupled with underlying lithospheric mantle and does not flow into the surrounding lithospheres, casting doubt on the lower crust flow model. We suggest that the Himalayan-Tibetan orogenic system can be best understood within the framework that the proto-southern Asian margin was fairly weak prior to the India-Asia collision to steer the formation of a large hot orogenic plateau there.

  14. Microstructure Evolution and Hardness of an Ultra-High Strength Cu-Ni-Si Alloy During Thermo-mechanical Processing

    NASA Astrophysics Data System (ADS)

    Lei, Q.; Li, Z.; Hu, W. P.; Liu, Y.; Meng, C. L.; Derby, B.; Zhang, W.

    2016-05-01

    Microstructure evolution and hardness changes of an ultra-high strength Cu-Ni-Si alloy during thermo-mechanical processing have been investigated. For hot-compressive deformation specimens, dynamic recrystallization preferentially appeared on deformation bands. As deformation temperature increased from 750 to 900 °C, elongated grains with the Cubic texture {001} <100> were substituted by recrystallized grains with Copper texture {112} <111>. For the samples having undergone cold rolling followed by annealing, static recrystallization preferentially occurred in the deformation bands, and then complete recrystallization occurred. Goss, Cubic, and Brass textures remained after annealing at 600 and 700 °C for 1 h; R texture {111} <211> and recrystallization texture {001} <100> were formed in samples annealed at 800 and 900 °C for 1 h, respectively. For samples processed under multi-directional forging at cryogenic temperature, the hardness was increased as a result of work hardening and grain refinement strengthening. These were attributed to the formation of equiaxed sub-grain structures and a high dislocation density.

  15. Metamorphic record and Thermo-mechanical modelling of lower crust exhumation during the Palaeoproterozoic Eburnean orogeny, West African Craton

    NASA Astrophysics Data System (ADS)

    Gerbault, Muriel; Ganne, Jerome; Block, Sylvain

    2014-05-01

    A thermo-mechanical interpretation of the metamorphic evolution of moderate- to high-pressure volcano-sedimentary rocks (6-8 to >10 Kb) in the Birimian Province (2.2-2.0 Ga) of the West African Craton is explored in terms of burial and exhumation processes. Metamorphic data collected in Burkina Faso, southwest Ghana and eastern Senegal suggest that during the Eburnean orogeny (~2.1 Ga),this Palaeoproterozoic Birimian crust was dominated by moderate apparent geothermal gradients of 20-30°C/km (M2a), that produced greenschist- to amphibolite-facies metamorphic assemblages associated with regional shortening and granitoid intrusions. The M2a gradient is superimposed on a colder thermal regime (M1 : <10-15 °C/km) that produced high-P greenschist- to blueschist-facies metamorphic assemblages, and which most likely recorded the earlier formation of the protolith. The geodynamical origin of M1 is not directly addressed here. Thermo-mechanical two-dimensional numerical models were built in order to test whether late-stage compressional tectonics could generate the exhumation of meta-sediments, collected in Ca0-poor granitoids and which record elevated metamorphic pressures (P> 6-8 Kb). The poor data quality provide limited constraints on the appropriate initial setup conditions, and a number of tests have led us to conceptualize the spatial distribution of a hypothezised succession of volcanic island arcs emplaced on top of CaO rich TTG (Tonalite- Trondjhemite-Granodiorite suites) basement, tectonically paired with sedimentary basins. We postulated therefore the preexistence of wide (about 250 km) and thick flexural sedimentary basins (depth 15 km) in an orogenic mafic crust (about 20 km thick), underplated by a more felsic and lighter layer representing a TTG melange. The numerical results show that a mechanism of burial, heating and exhumation of meta-sediments can occur by simultaneous folding and gravitational instabilities within the broad extent of the basin

  16. Effect of thermo-mechanical cycling on zirconium hydride reorientation studied in situ with synchrotron X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Colas, Kimberly B.; Motta, Arthur T.; Daymond, Mark R.; Almer, Jonathan D.

    2013-09-01

    The circumferential hydrides normally present in nuclear reactor fuel cladding after reactor exposure may dissolve during drying for dry storage and re-precipitate when cooled under load into a more radial orientation, which could embrittle the fuel cladding. It is necessary to study the rates and conditions under which hydride reorientation may happen in order to assess fuel integrity in dry storage. The objective of this work is to study the effect of applied stress and thermal cycling on the hydride morphology in cold-worked stress-relieved Zircaloy-4 by combining conventional metallography and in situ X-ray diffraction techniques. Metallography is used to study the evolution of hydride morphology after several thermo-mechanical cycles. In situ X-ray diffraction performed at the Advanced Photon Source synchrotron provides real-time information on the process of hydride dissolution and precipitation under stress during several thermal cycles. The detailed study of diffracted intensity, peak position and full-width at half-maximum provides information on precipitation kinetics, elastic strains and other characteristics of the hydride precipitation process. The results show that thermo-mechanical cycling significantly increases the radial hydride fraction as well as the hydride length and connectivity. The radial hydrides are observed to precipitate at a lower temperature than circumferential hydrides. Variations in the magnitude and range of hydride strains due to reorientation and cycling have also been observed. These results are discussed in light of existing models and experiments on hydride reorientation. The study of hydride elastic strains during precipitation shows marked differences between circumferential and radial hydrides, which can be used to investigate the reorientation process. Cycling under stress above the threshold stress for reorientation drastically increases both the reoriented hydride fraction and the hydride size. The reoriented hydride

  17. Reconstructions of the Weichselian ice sheet, a comparative study of a thermo-mechanical approach to GIA driven models.

    NASA Astrophysics Data System (ADS)

    Schmidt, Peter; Lund, Björn; Näslund, Jens-Ove; Fastook, James

    2014-05-01

    Observations of glacial isostatic adjustment (GIA) have been used both to study the mechanical properties of the Earth and to invert for Northern Hemisphere palaeo-ice-sheets. This is typically done by solving the sea-level equation using simplified scaling laws to control ice-sheet thickness. However, past ice-sheets can also be reconstructed based on thermo-mechanical modelling driven by palaeo-climate data, invoking simple analytical models to account for the Earth's response. Commonly, both approaches use dated geological markers to constrain the ice-sheet margin location. Irrespective of the approach, the resulting ice-sheet reconstruction depends on the earth response, although the interdependence between the ice model and the earth model differs and therefore the two types of reconstructions could provide complementary information on Earth properties. We compare a thermo-mechanical reconstruction of the Weichselian ice-sheet using the UMISM model (Näslund, 2010) to two GIA driven reconstructions, ANU (Lambeck et al., 2010) and ICE-5G (Peltier & Fairbanks, 2006), commonly used in GIA modelling. We evaluate the three reconstructions both in terms of ice-sheet configurations and predicted Fennoscandian surface deformation ICE-5G comprise the largest reconstructed ice-sheet whereas ANU and UMISM are more similar in volume and areal extent. Significant differences still exists between ANU and UMISM, especially during the final deglaciation phase. Prior to the final retreat of the ice-sheet, ICE-5G is displays a massive and more or less constant ice-sheet configuration, while both ANU and UMISM fluctuates with at times almost ice-free conditions, such as during MIS3. This results in ICE-5G being close to isostatic equilibrium at LGM, whereas ANU and UMISM are not. Hence, the pre-LGM evolution of the Weichselian ice-sheet needs to be considered in GIA studies. For example, perturbing the ANU or UMISM reconstructions we find that changes more recent than 36 kyr BP

  18. Development and demonstration of the use of modular thermo-mechanical pulpmill simulation models to develop energy reduction strategies

    SciTech Connect

    Rushton, J.D.; Jones, G.L. ); Leaver, E.L.; Morton, W. )

    1991-08-15

    The Institute of Paper Science and Technology (IPST) has received a project grant from the US DOE to develop and demonstrate the use of realtime process simulation modeling as a means of process analysis and optimization. The Project, to be conducted under the auspices of the International Energy Agency (IEA), will target a Thermo-Mechanical Pulping (TMP) operation as the site for the commercial implementation of the technology. IPST and a sub-contractor, SACDA Inc. (SACDA), will cooperate in a two-to-three year effort to produce an on-line simulation program having both steady-state and dynamic modeling capabilities. The Project will take advantage of a current IPST and SACDA joint development effort to merge the IPST's MAPPS (Modular Analysis of Pulp and Paper Systems) program with SACD's MASSBAL program. Using the combined proprietary programs, realtime'' steady-state and dynamic TMP models will be developed and installed as part of a millwide'' information/analysis system. By utilizing the Performance Attribute (PAT) Modeling concept developed at IPST, the models will have the capability of optimizing energy usage and other process operating variables as a function of pulp quality. The primary goal of the Project is to demonstrate that on-line simulation models can provide assistance to operators and managers in day-to-day operations. By embedding simulation analysis techniques such as data reconciliation and what if,'' optimization, and look ahead'' scenarios within the program executive, timely process data and information, not otherwise available, will be provided to the operator. Such data and information can be used by the operator for process analysis, optimization and planning and/or to provide setpoints for open or closed loop advanced control strategies.

  19. Lead transport in intra-oceanic subduction zones: 2D geochemical-thermo-mechanical modeling of isotopic signatures

    NASA Astrophysics Data System (ADS)

    Baitsch-Ghirardello, Bettina; Stracke, Andreas; Connolly, James A. D.; Nikolaeva, Ksenia M.; Gerya, Taras V.

    2014-11-01

    Understanding the physical-chemical mechanisms and pathways of geochemical transport in subduction zones remains a long-standing goal of subduction-related research. In this study, we perform fully coupled geochemical-thermo-mechanical (GcTM) numerical simulations to investigate Pb isotopic signatures of the two key "outputs" of subduction zones: (A) serpentinite mélanges and (B) arc basalts. With this approach we analyze three different geodynamic regimes of intra-oceanic subduction systems: (1) retreating subduction with backarc spreading, (2) stable subduction with high fluid-related weakening, and (3) stable subduction with low fluid-related weakening. Numerical results suggest a three-stage Pb geochemical transport in subduction zones: (I) from subducting sediments and oceanic crust to serpentinite mélanges, (II) from subducting serpentinite mélanges to subarc asthenospheric wedge and (III) from the mantle wedge to arc volcanics. Mechanical mixing and fluid-assisted geochemical transport above slabs result in spatially and temporarily variable Pb concentrations in the serpentinized forearc mantle as well as in arc basalts. The Pb isotopic ratios are strongly heterogeneous and show five types of geochemical mixing trends: (i) binary mantle-MORB, (i) binary MORB-sediments, (iii) double binary MORB-mantle and MORB-sediments, (iv) double binary MORB-mantle and mantle-sediments and (v) triple MORB-sediment-mantle. Double binary and triple mixing trends are transient and characterize relatively early stages of subduction. In contrast, steady-state binary mantle-MORB and MORB-sediments trends are typical for mature subduction zones with respectively low and high intensity of sedimentary melange subduction. Predictions from our GcTM models are in agreement with Pb isotopic data from some natural subduction zones.

  20. Thermo-mechanically coupled subduction using AMR together with a true free surface and sticky air in ASPECT

    NASA Astrophysics Data System (ADS)

    Fraters, Menno; Glerum, Anne; Thieulot, Cedric; Spakman, Wim

    2015-04-01

    ASPECT (Kronbichler et al., 2012), short for Advanced Solver for Problems in Earth's ConvecTion, is a new Finite Element code which was originally designed for thermally driven (mantle) convection and is built on state of the art numerical methods (adaptive mesh refinement, linear and non-linear solver, stabilization of transport dominated processes and a high scalability on multiple processors). Here we present an application of ASPECT to the modelling of fully thermo-mechanically coupled subduction. Our model contains in the case of a true free surface three different compositions: two different crustal compositions, one on top of the subducting plate and one on top of the overriding plate, and a mantle composition. In the case of a free surface through a sticky air layer, a fourth composition representing this sticky air is added. We implemented a viscoplastic rheology using frictional plasticity and a composite viscosity defined by diffusion and dislocation creep. The lithospheric part of the mantle has the same composition as the rest of the mantle but has a higher viscosity because of a lower temperature. The temperature field is implemented in ASPECT as follows: a linear temperature gradient for the lithosphere and an adiabatic geotherm for the sublithospheric mantle. The Initial slab temperature is defined using the analytical solution of McKenzie (1970). The plates can be pushed from the sides of the model, and correspondingly it is possible to define an additional independent mantle in/out flow through the boundaries. We will show a preliminary set of models, highlighting the current codes capabilities, such as the fine tuned use of Adaptive Mesh Refinement in combination with topography development both through a true free surface and sticky air and solving for strongly non-linear rheologies.

  1. NEP power subsystem modeling

    NASA Technical Reports Server (NTRS)

    Harty, Richard B.

    1993-01-01

    The Nuclear Electric Propulsion (NEP) system optimization code consists of a master module and various submodules. Each of the submodules represents a subsystem within the total NEP power system. The master module sends commands and input data to each of the submodules and receives output data back. Rocketdyne was responsible for preparing submodules for the power conversion (both K-Rankine and Brayton), heat rejection, and power management and distribution.

  2. Pressure Garment Subsystem Roadmap

    NASA Technical Reports Server (NTRS)

    Ross, Amy J.

    2010-01-01

    The Constellation program pressure garment subsystem (PGS) team has created a technical roadmap that communicates major technical questions and how and when the questions are being answered in support of major project milestones. The roadmap is a living document that guides the team priorities. The roadmap also communicates technical reactions to changes in project priorities and funding. This paper presents the roadmap and discusses specific roadmap elements in detail as representative examples to provide insight into the meaning and use of the roadmap.

  3. The MAP Propulsion Subsystem

    NASA Technical Reports Server (NTRS)

    Davis, Gary T.; Bauer, Frank H. (Technical Monitor)

    2002-01-01

    This paper describes the requirements, design, integration, test, performance, and lessons learned of NASA's Microwave Anisotropy Probe (MAP) propulsion subsystem. MAP was launched on a Delta-II launch vehicle from NASA's Kennedy Space Center on June 30, 2001. Due to instrument thermal stability requirements, the Earth-Sun L2 Lagrange point was selected for the mission orbit. The L2 trajectory incorporated phasing loops and a lunar gravity assist. The propulsion subsystem's requirements are to manage momentum, perform maneuvers during the phasing loops to set up the lunar swingby, and perform stationkeeping at L2 for 2 years. MAP's propulsion subsystem uses 8 thrusters which are located and oriented to provide attitude control and momentum management about all axes, and delta-V in any direction without exposing the instrument to the sun. The propellant tank holds 72 kg of hydrazine, which is expelled by unregulated blowdown pressurization. Thermal management is complex because no heater cycling is allowed at L2. Several technical challenges presented themselves during I and T, such as in-situ weld repairs and in-situ bending of thruster tubes to accommodate late changes in the observatory CG. On-orbit performance has been nominal, and all phasing loop, mid-course correction, and stationkeeping maneuvers have been successfully performed to date.

  4. Pressure relief subsystem design description

    SciTech Connect

    1986-07-01

    The primary function of the Pressure Relief Subsystem, a subsystem of the Vessel System, is to provide overpressure protection to the Vessel System. When the overpressure setpoint is reached, pressure is reduced by permitting the flow of primary coolant out of the Vessel System. This subsystem also provides the flow path by which purified helium is returned to the vessel system, either as circulating purge/flow from the Helium Purification Subsystem or make-up helium from the Helium Storage and Transfer Subsystem.

  5. 3D thermo-mechanical models of continental breakup and transition from rifting to continental break-up and spreading

    NASA Astrophysics Data System (ADS)

    Koptev, Alexander; Burov, Evgueni; Gerya, Taras

    2014-05-01

    We conducted high-resolution 3D thermo-mechanical numerical modeling experiments to explore evolution and styles of plume-activated rifting in presence of preexisting far-field tectonic stress/strain field and tectonic heritage (in form of cratonic blocks embedded in «normal lithosphere»). The experiments demonstrate strong dependence of rifting style on preexisting far-field tectonic stress/strain field and initial thermo-rheological profile, as well as on the tectonic heritage. The models with homogeneous lithosphere demonstrate strongly non-linear impact of far-field extension rates on timing of break-up processes. Experiments with relatively fast far-field extension (6 mm/y) show intensive normal fault localization in crust and uppermost mantle above the zones of plume-head emplacement some 15-20 Myrs after the onset of the experiment. When plume head material reaches the bottom of the continental crust (at ~25 Myrs), the latter is rapidly ruptured (<1 Myrs) and several steady oceanic floor spreading centers develop. Slower (3 mm/y) far-field velocities result in disproportionally longer break-up time (from 60 to 70 Myrs depending on initial isoterm at the crust bottom). Although in all experiments with homogeneous lithosphere spreading centers have similar orientation perpendicular to the direction of far-field extension, their number and spatial location are different for different extension rates and thermo-rheological structures of the lithosphere. On the contrary, in case of normal lithosphere containing embedded cratonic block, spreading zones develop symmetrically, embracing cratonic micro-plate along its long sides. Presence of cratonic blocks leads to splitting of the plume head onto initially nearly symmetrical parts, each of which flows towards beneath the craton borders. This craton-controlled distribution of plume material causes the crustal strain localization and uprise of plume material along the craton boundaries. Though there is a net

  6. A new code for predicting the thermo-mechanical and irradiation behavior of metallic fuels in sodium fast reactors

    NASA Astrophysics Data System (ADS)

    Karahan, Aydın; Buongiorno, Jacopo

    2010-01-01

    An engineering code to predict the irradiation behavior of U-Zr and U-Pu-Zr metallic alloy fuel pins and UO2-PuO2 mixed oxide fuel pins in sodium-cooled fast reactors was developed. The code was named Fuel Engineering and Structural analysis Tool (FEAST). FEAST has several modules working in coupled form with an explicit numerical algorithm. These modules describe fission gas release and fuel swelling, fuel chemistry and restructuring, temperature distribution, fuel-clad chemical interaction, and fuel and clad mechanical analysis including transient creep-fracture for the clad. Given the fuel pin geometry, composition and irradiation history, FEAST can analyze fuel and clad thermo-mechanical behavior at both steady-state and design-basis (non-disruptive) transient scenarios. FEAST was written in FORTRAN-90 and has a simple input file similar to that of the LWR fuel code FRAPCON. The metal-fuel version is called FEAST-METAL, and is described in this paper. The oxide-fuel version, FEAST-OXIDE is described in a companion paper. With respect to the old Argonne National Laboratory code LIFE-METAL and other same-generation codes, FEAST-METAL emphasizes more mechanistic, less empirical models, whenever available. Specifically, fission gas release and swelling are modeled with the GRSIS algorithm, which is based on detailed tracking of fission gas bubbles within the metal fuel. Migration of the fuel constituents is modeled by means of thermo-transport theory. Fuel-clad chemical interaction models based on precipitation kinetics were developed for steady-state operation and transients. Finally, a transient intergranular creep-fracture model for the clad, which tracks the nucleation and growth of the cavities at the grain boundaries, was developed for and implemented in the code. Reducing the empiricism in the constitutive models should make it more acceptable to extrapolate FEAST-METAL to new fuel compositions and higher burnup, as envisioned in advanced sodium reactors

  7. Thermo-Mechanical Optimization of a Gold Thick-film based SiC Die-attach Assembly using Finite Element Analysis

    NASA Technical Reports Server (NTRS)

    Lin, Shun-Tien; Chen, Liang-Yu

    2002-01-01

    A parametric study of the thermomechanical reliability of a Au thick-film based Sic-die- attach assembly using nonlinear finite element analysis (FEA) was conducted to optimize the die-attach thermo-mechanical performance for operation at temperatures from room temperature to 500 "C. This parametric study centered on material selection, structure design and process control. The die-attach assembly is composed of a 1 mm x 1 mm S i c die attached to a ceramic substrate (either 96% aluminum oxide (A1203) or aluminum nitride (AlN)) with a gold (Au) thick-film attach layer. The effects of die-size, Au attach layer thickness, substrate material, and stress relaxing temperature on the stress/strain distribution and relative fatigue lifetime of the die-attach assembly were numerically analyzed. By comparing the calculated permanent strain in the thick-film attach layer, FEA results indicate that AlN is superior to Al2O3. Thicker Au attach layers and smaller die sizes are recommended to reduce the permanent strain in thick-film die attach layer. Thicker S i c die also reduces the stress near the (top) surface region of the die. A stress relaxing temperature close to the midpoint of the operating temperature range further reduces the maximum stress/strain, thereby improving die-attach thermo-mechanical reliability. These recommendations present guidelines to optimize the thermo-mechanical performance of the die-attach assembly and are valid for a wide range of thermal environments.

  8. Counterflowing Jet Subsystem Design

    NASA Technical Reports Server (NTRS)

    Farr, Rebecca; Daso, Endwell; Pritchett, Victor; Wang, Ten-See

    2010-01-01

    A counterflowing jet design (a spacecraft and trans-atmospheric subsystem) employs centrally located, supersonic cold gas jets on the face of the vehicle, ejecting into the oncoming free stream. Depending on the supersonic free-stream conditions and the ejected mass flow rate of the counterflowing jets, the bow shock of the vehicle is moved upstream, further away from the vehicle. This results in an increasing shock standoff distance of the bow shock with a progressively weaker shock. At a critical jet mass flow rate, the bow shock becomes so weak that it is transformed into a series of compression waves spread out in a much wider region, thus significantly modifying the flow that wets the outer surfaces, with an attendant reduction in wave and skin friction drag and aerothermal loads.

  9. In-situ neutron diffraction study of martensitic variant redistribution in polycrystalline Ni-Mn-Ga alloy under cyclic thermo-mechanical treatment

    SciTech Connect

    Li, Zongbin; Zou, Naifu; Zhao, Xiang; Zuo, Liang E-mail: yudong.zhang@univ-lorraine.fr; Zhang, Yudong E-mail: yudong.zhang@univ-lorraine.fr; Esling, Claude; Gan, Weimin

    2014-07-14

    The influences of uniaxial compressive stress on martensitic transformation were studied on a polycrystalline Ni-Mn-Ga bulk alloy prepared by directional solidification. Based upon the integrated in-situ neutron diffraction measurements, direct experimental evidence was obtained on the variant redistribution of seven-layered modulated (7M) martensite, triggered by external uniaxial compression during martensitic transformation. Large anisotropic lattice strain, induced by the cyclic thermo-mechanical treatment, has led to the microstructure modification by forming martensitic variants with a strong 〈0 1 0〉{sub 7M} preferential orientation along the loading axis. As a result, the saturation of magnetization became easier to be reached.

  10. Deformation of plate boundaries associated with subduction of continental margins: insights from 3D thermo-mechanical laboratory experiments (Invited)

    NASA Astrophysics Data System (ADS)

    Boutelier, D. A.; Cruden, A. R.

    2013-12-01

    The general sequence of tectonic events leading to the formation of collisional mountain belts includes closure of an ocean basin through oceanic subduction, subduction of a continental margin and deformation of the lithosphere. Laboratory experiments reproducing this fundamental chain of events investigate the three-dimensional and thermo-mechanical mechanics of the associated processes. Experiments reveal that this basic scenario can be considerably modified at the beginning of continental subduction. The buoyancy of the subducted passive margin causes a strong horizontal compression in the plates, which can lead to the formation of new thrusts in the magmatic arc or back-arc spreading center if the collision was preceded by oceanic subduction in the tensile regime. Several complex scenarios can develop, depending on the polarity of the new thrusts. If the new thrust in the arc or back-arc has the same polarity as the main subduction zone, the entire area located between the trench and the new thrust can be subducted, leaving little evidence of its former existence in the geological record. This process also modifies the thermal and mechanical regime of the subducted lithosphere, resulting in lower temperatures in the subducted crust thereby allowing deeper subduction. If the polarity of the new thrust is opposite to that of the existing subduction zone, the two slabs collide at depth, with the new slab generally cutting through the pre-existing slab. The distribution of convergence across several thrusts necessarily leads to a reduction of the convergence rate on the pre-existing subduction thrust. This leads to a reduction of the viscous coupling supporting the subducted lithosphere, causing an increase in downdip tension in the slab, and a rapid decrease of the slab strength due to temperature increase, eventually leading to slab break-off. Finally, the deformation caused by the subduction of the buoyant continental crust is fundamentally three

  11. Thermo-mechanical modeling of continental rift evolution over mantle upwelling in presence of far-field stresses

    NASA Astrophysics Data System (ADS)

    Koptev, Alexander; Burov, Evgueni; Calais, Eric; Leroy, Sylvie; Gerya, Taras

    2016-04-01

    We conducted fully-coupled high resolution rheologically consistent 3D thermo-mechanical numerical models to investigate the processes of mantle-lithosphere interaction (MLI) in presence of preexisting far-field tectonic stresses. MLI-induced topography exhibits strongly asymmetric small-scale 3D features, such as rifts, flexural flank uplifts and complex faults structures. This suggests a dominant role of continental rheological structure and intra-plate stresses in controlling continental rifting and break-up processes above mantle upwelling while reconciling the passive (far-field tectonic stresses) versus active (plume-activated) rift concepts as our experiments show both processes in action. We tested different experiments by varying two principal controlling parameters: 1) horizontal extension velocity and 2) Moho temperature used as simplified indicator of the thermal and rheological lithosphere layering. An increase in the applied extension expectedly gives less localized deformation at lithospheric scale: the growth of external velocity from 1.5 mm/years to 6 mm/years leads to enlargement of the rift zones from 75-175 km to 150-425 km width. On the contrary, increasing of the lithospheric geotherm has an opposite effect leading to narrowing of the rift zone: the change of the Moho isotherm from 600°C to 800°C causes diminution of the rift width from 175-425 km to 75-150 km. Some of these finding are contra-intuitive in terms of usual assumptions. The models refer to strongly non-linear impact of far-field extension rates on timing of break-up processes. Experiments with relatively fast far-field extension (6 mm/years) show intensive normal fault localization in crust and uppermost mantle above the plume head at 15-20 Myrs after the onset of the experiment. When plume head material reaches the bottom of the continental crust (at 25 Myrs), the latter is rapidly ruptured (<1 Myrs) and several steady oceanic floor spreading centers develop. Slower (3 mm

  12. Normal-Mode Excitation by Sumatran Earthquake and Short-Timescale THERMO-MECHANICS AND RHEOLOGY OF THE EARTH'S LITHOSPHERE

    NASA Astrophysics Data System (ADS)

    Regenauer-Lieb, K.; Yuen, D. A.

    2005-05-01

    Solutions of the free-oscillation amplitudes,excited by the recent Sumatran wallop, by Okal and Stein ( 2005 ) have revealed a linearly growing trend in the semi-log plot between amplitude and period from 300 seconds to around an hour. This tantalizing plot (http://www.earth.northwestern.edu/people/seth/research/sumatra.html ) is very much reminiscent of the Rayleigh-Jeans portion of the Planck function in radiation physics, which was called the ultra-violet catastrophe. This distinct signature at long periods shows that some other physics must intervene to neutralize this singular tendency at a longer timescale. Thus in earthquake thermo-mechanics the size of an earthquake or moment is analogous to temperature in statistical physics. In this vein we have studied the thermal-mechanical shear interaction within the framework of a two-dimensional time-dependent model wherein a realistic visco-elastic-plastic rheology is implemented, and the governing equations include the momentum equation without inertia, the rheological and energy equations. We have retained all mechanical heating terms and heating terms involving volumetric expansion in the energy eq uation. In our simulations wherein we have modeled a bending situation, we encou nter two basically different bifurcation phenomena at the brittle-ductile transition-zone in the lithosphere, which can be attributed to two different families of eigenmodes of the system. One in which the shear zone nucleates on thermal perturbations in the ductile field, and the second which is fully associated with elasto-plastic (brittle, pressure-dependent) displacements. A quartz slab has all two modes operating simultaneously at three different depth levels. The bottom of the crust is controlled by the elasto-visco-plastic mode while the top is controlled by the elasto-plastic mode. The exchange of the two modes appears to communicate on a sub-horizontal layer in a flip-flop fashion, which may yield a fractal-like signature in time

  13. Simulation of the irradiation-induced micro-thermo-mechanical behaviors evolution in ADS nuclear fuel pellets

    NASA Astrophysics Data System (ADS)

    Ding, Shurong; Zhao, Yunmei; Wan, Jibo; Gong, Xin; Wang, Canglong; Yang, Lei; Huo, Yongzhong

    2013-11-01

    An Accelerator Driven System (ADS) is dedicated to Minor Actinides (MA) transmutation. The fuels for ADS are highly innovative, which are composite fuel pellets with the fuel particles containing MA phases dispersed in a MgO or Mo matrix. Assuming that the fuel particles are distributed periodically in the MgO matrix, a three-dimensional finite element model is developed. The three-dimensional incremental large-deformation constitutive relations for the fuel particles and matrix are separately built, and a method is accordingly constructed to implement simulation of the micro-thermo-mechanical behaviors evolution. Evolutions of the temperature and mechanical fields are given and discussed. With irradiation creep included in the MgO matrix constitutive relation, the conclusions can be drawn as that (1) irradiation creep has a remarkable effect on the mechanical behaviors evolution in the matrix; (2) irradiation creep plays an important role in the damage mechanism interpretation of ceramic matrix fuel pellets. Thermal conductivity The thermal conductivity model is adopted as KUO2 = K0·FD·FP·FM·FR, which was proposed by Lucuta et al. [10] to adapt to the high burnup conditions with consideration of the effects of temperature, burnup, porosity and fission products. K0 is the thermal conductivity of fully dense un-irradiated UO2, as Eq. (1) in W/m K; FD, FP are the adjust factors reflecting the effects of dissolved and precipitated fission products; FM and FR are factors due to porosity and irradiation effects. The adopted thermal conductivity varies with temperature and burnup, which expresses its degradation with burnup, with the terms as k0={1}/{0.0375+2.165×10-4T}+{4.715×109}/{T2}exp-{16361}/{T} FD={1.09}/{B3.265}+{0.0643}/{√{B}}√{T}artan{1}/{1.09/B3.265}+{0.0643}/{√{B}}√{T} FP=1+0.019B/3-0.019B{1}/{1+exp(1200-T100)} FM={1-P}/{1+(s-1)P} FR=1-{0.2}/{1+expT-90080} Thermal expansion The engineering strain of thermal expansion [11] is given as {ΔL}/{L0

  14. Effect of Multipass TIG and Activated TIG Welding Process on the Thermo-Mechanical Behavior of 316LN Stainless Steel Weld Joints

    NASA Astrophysics Data System (ADS)

    Ganesh, K. C.; Balasubramanian, K. R.; Vasudevan, M.; Vasantharaja, P.; Chandrasekhar, N.

    2016-04-01

    The primary objective of this work was to develop a finite element model to predict the thermo-mechanical behavior of an activated tungsten inert gas (ATIG)-welded joint. The ATIG-welded joint was fabricated using 10 mm thickness of 316LN stainless steel plates in a single pass. To distinguish the merits of ATIG welding process, it was compared with manual multipass tungsten inert gas (MPTIG)-welded joint. The ATIG-welded joint was fabricated with square butt edge configuration using an activating flux developed in-house. The MPTIG-welded joint was fabricated in thirteen passes with V-groove edge configuration. The finite element model was developed to predict the transient temperature, residual stress, and distortion of the welded joints. Also, microhardness, impact toughness, tensile strength, ferrite measurement, and microstructure were characterized. Since most of the recent publications of ATIG-welded joint was focused on the molten weld pool dynamics, this research work gives an insight on the thermo-mechanical behavior of ATIG-welded joint over MPTIG-welded joint.

  15. Influence of the interface structure on the thermo-mechanical properties of Cu-X (X = Cr or B)/carbon fiber composites

    SciTech Connect

    Veillere, A.; Heintz, J.-M.; Chandra, N.; Douin, J.; Lahaye, M.; Lalet, G.; Vincent, C.; Silvain, J.-F.

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Two copper alloys/carbon fibers composites have been produced. Black-Right-Pointing-Pointer Correlation of the thermo-mechanical properties with the microstructure and the chemistry. Black-Right-Pointing-Pointer A composite with CTE 25% lower than a classic Cu/CF composite has been obtained. -- Abstract: This study focuses on the fabrication, for power electronics applications, of adaptive heat sink material using copper alloys/carbon fibers (CF) composites. In order to obtain composite material with good thermal conductivity and a coefficient of thermal expansion close to the ceramic substrate, it is necessary to have a strong matrix/reinforcement bond. Since there is no reaction between copper and carbon, a carbide element (chromium or boron) is added to the copper matrix to create a strong chemical bond. Composite materials (Cu-B/CF and Cu-Cr/CF) have been produced by a powder metallurgy process followed by an annealing treatment in order to create the carbide at the interphase. Chemical (Electron Probe Micro-Analysis, Auger Electron Spectroscopy) and microstructural (Scanning and Transmission Electron Microscopies) techniques were used to study the location of the alloying element and the carbide formation before and after diffusion. Finally, the thermo-mechanical properties have been measured and a promising composite material with a coefficient of thermal expansion 25% lower than a classic copper/carbon heat sink has been obtained.

  16. Influences of Strain Rate and Load Direction on the Thermo-mechanical Behavior of a Nano-Alumina-Containing Copper Alloy Bar

    NASA Astrophysics Data System (ADS)

    Guo, Mingxing; Wang, Fei; Huang, Guojie; Bi, Wenlu; Zhang, Yan; Wang, Mingpu

    2015-10-01

    The effects of strain rate and load direction on the thermo-mechanical behavior of Cu-2.7vol.%Al2O3 alloy bar with high strength and electrical conductivity were investigated. The results show that the thermo-mechanical behavior of the alloy changes greatly with changing load direction or strain rate. For the same compression strain rate, the peak yield stress in the longitudinal compression is much higher than that of transverse compression. The homogeneous distribution of dynamic recrystallization grains or subgrains after longitudinal compression is much higher than that of transverse compression. For the longitudinal or transverse compression, the size of dynamical recrystallization grains decreases with increasing strain rate, the initial elongated bands can only be observed in the transverse compressions due to the effect of load direction. The flow stress oscillation phenomenon appears in both transverse and longitudinal compressions with a strain rate of 20 s-1. Accordingly, the relationship between flow stress and microstructure, and a model of dynamic recrystallization in the transverse and longitudinal compressions, were established and analyzed in this paper.

  17. Thermo-Mechanical Response of a TRISO Fuel Particle in a Fusion/Fission Engine for Incineration of Weapons Grade Plutonium

    SciTech Connect

    Caro, M; DeMange, P; Marian, J; Caro, A

    2009-12-08

    The Laser Inertial Fusion-based (LIFE) engine is an advanced energy concept under development at Lawrence Livermore National Laboratory (LLNL). LIFE engine could be used to drive a subcritical fission blanket with fertile or fissile fuel. Current LIFE engine designs envisages fuel in pebble bed form with TRISO (tristructural isotropic) particles embedded in a graphite matrix, and pebbles flowing in molten salt Flibe (2LiF+BeF{sub 2}) coolant at T {approx} 700C. Weapons-grade plutonium (WGPu) fuel is an attractive option for LIFE engine involving the achievement of high fractional burnups in a short lifetime frame. However, WGPu LIFE engine operating conditions of high neutron fast fluence, high radiation damage, and high Helium and Hydrogen production pose severe challenges for typical TRISO particles. The thermo-mechanical fuel performance code HUPPCO (High burn-Up fuel Pebble Performance COde) currently under development accounts for spatial and time dependence of the material elastic properties, temperature, and irradiation swelling and creep mechanisms. In this work, some aspects of the thermo-mechanical response of TRISO particles used for incineration of weapons grade fuel in LIFE engine are analyzed. Preliminary results show the importance of developing reliable high-fidelity models of the performance of these new fuel designs and the need of new experimental data relevant to WGPu LIFE conditions.

  18. Waste collection subsystem study

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Practical ways were explored of improving waste compaction and of providing rapid turnaround between flights at essentially no cost for the space shuttle waste collection subsystem commode. Because of the possible application of a fully developed shuttle commode to the space station, means of providing waste treatment without overboard venting were also considered. Three basic schemes for compaction and rapid turnaround, each fully capable of meeting the objectives, were explored in sufficient depth to bring out the characteristic advantages and disadvantages of each. Tradeoff comparisons were very close between leading contenders and efforts were made to refine the design concepts sufficiently to justify a selection. The concept selected makes use of a sealed canister containing wastes that have been forcibly compacted, which is removable in flight. No selection was made between three superior non-venting treatment methods owing to the need for experimental evaluations of the processes involved. A system requirements definition document has been prepared to define the task for a test embodiment of the selected concept.

  19. Mars Exploration Rover telecommunications subsystem

    NASA Astrophysics Data System (ADS)

    Hilland, Jeffrey; Bhanji, Alaudin M.; Estabrook, Polly

    2004-04-01

    The Mars Exploration Rover (MER) mission is designed to investigate Martian geology, investigate the role of water, and seek information on the climate history of the red planet at two sites. The Telecommunications Subsystem consists of the Radio Frequency Subsystem (RFS) operating at 7.1/8.4GHz (X-band), the Ultra High Frequency (UHF) Subsystem operating at 401/437MHz, the RFS and UHF Antenna Subsystem and the Radar Altimeter Subsystem (RAS) operating at 4.3 GHz (C-band). Science data return is enhanced through UHF relay communications with the Mars Odyssey (ODY) orbiter up to 128 kbps. Relay communications will also be demonstrated with the ESA Mars Express orbiter.

  20. Subsystems component definitions summary program

    NASA Technical Reports Server (NTRS)

    Scott, A. Don; Thomas, Carolyn C.; Simonsen, Lisa C.; Hall, John B., Jr.

    1991-01-01

    A computer program, the Subsystems Component Definitions Summary (SUBCOMDEF), was developed to provide a quick and efficient means of summarizing large quantities of subsystems component data in terms of weight, volume, resupply, and power. The program was validated using Space Station Freedom Program Definition Requirements Document data for the internal and external thermal control subsystem. Once all component descriptions, unit weights and volumes, resupply, and power data are input, the user may obtain a summary report of user-specified portions of the subsystem or of the entire subsystem as a whole. Any combination or all of the parameters of wet and dry weight, wet and dry volume, resupply weight and volume, and power may be displayed. The user may vary the resupply period according to individual mission requirements, as well as the number of hours per day power consuming components operate. Uses of this program are not limited only to subsystem component summaries. Any applications that require quick, efficient, and accurate weight, volume, resupply, or power summaries would be well suited to take advantage of SUBCOMDEF's capabilities.

  1. The influence of low-strain thermo-mechanical processing on grain boundary network characteristics in type 304 austenitic stainless steel.

    PubMed

    Engelberg, D L; Humphreys, F J; Marrow, T J

    2008-06-01

    Grain boundary engineering of austenitic stainless steel, through the introduction of plastic strain and thermal annealing, can be used to develop microstructures with improved resistance to inter-granular degradation. The influence of low-strain thermo-mechanical processing on grain boundary network development, with systematic variations of annealing treatments, has been investigated. Three stages of the microstructure development during grain boundary engineering in low-strain processing conditions are identified, and correlated with changes in grain boundary character and deviation distributions. Low-energy connected length segments at triple junctions, which have been proposed to be responsible for crack bridging during inter-granular stress corrosion cracking, can be influenced by the choice of the annealing treatment parameters. The development of individual grain boundary length segments of different character showed consistent trends with increasing grain size. Crack length predictions are consistent with the beneficial effect of designing microstructures with high fractions of twin grain boundaries and smaller grain size. PMID:18503670

  2. Specification of CuCrZr Alloy Properties after Various Thermo-Mechanical Treatments and Design Allowables including Neutron Irradiation Effects

    SciTech Connect

    Barabash, Vladimir; Kalinin, G. M.; Fabritsiev, Sergei A.; Zinkle, Steven J

    2012-01-01

    Precipitation hardened CuCrZr alloy is a promising heat sink and functional material for various applica- tions in ITER, for example the first wall, blanket electrical attachment, divertor, and heating systems. Three types of thermo-mechanical treatment were identified as most promising for the various applica- tions in ITER: solution annealing, cold working and ageing; solution annealing and ageing; solution annealing and ageing at non-optimal condition due to specific manufacturing processes for engineer- ing-scale components. The available data for these three types of treatments were assessed and mini- mum tensile properties were determined based on recommendation of Structural Design Criteria for the ITER In-vessel Components. The available data for these heat treatments were analyzed for assess- ment of neutron irradiation effect. Using the definitions of the ITER Structural Design Criteria the design allowable stress intensity values are proposed for CuCrZr alloy after various heat treatments.

  3. Effect of microstructure on the coupled electromagnetic-thermo-mechanical response of cyclotrimethylenetrinitramine-estane energetic aggregates to infrared laser radiation

    SciTech Connect

    Brown, Judith A.; Zikry, M. A.

    2015-09-28

    The coupled electromagnetic (EM)-thermo-mechanical response of cyclotrimethylenetrinitramine-estane energetic aggregates under laser irradiation and high strain rate loads has been investigated for various aggregate sizes and binder volume fractions. The cyclotrimethylenetrinitramine (RDX) crystals are modeled with a dislocation density-based crystalline plasticity formulation and the estane binder is modeled with finite viscoelasticity through a nonlinear finite element approach that couples EM wave propagation with laser heat absorption, thermal conduction, and inelastic deformation. Material property and local behavior mismatch at the crystal-binder interfaces resulted in geometric scattering of the EM wave, electric field and laser heating localization, high stress gradients, dislocation density, and crystalline shear slip accumulation. Viscous sliding in the binder was another energy dissipation mechanism that reduced stresses in aggregates with thicker binder ligaments and larger binder volume fractions. This investigation indicates the complex interactions between EM waves and mechanical behavior, for accurate predictions of laser irradiation of heterogeneous materials.

  4. Transformation behavior and shape memory characteristics of thermo-mechanically treated Ti–(45−x)Ni–5Cu–xV (at%) alloys

    SciTech Connect

    Jang, Jae-young; Chun, Su-jin; Choi, Eunsoo; Liu, Yinong; Yang, Hong; Nam, Tae-hyun

    2012-10-15

    Transformation behavior, shape memory characteristics and superelasticity of thermo-mechanically treated Ti–(45−x)Ni–5Cu–xV (at%) (x = 0.5–2.0) alloys were investigated by means of differential scanning calorimetry, transmission electron microscopy, X-ray diffractions, thermal cycling tests under constant load and tensile tests. The B2–B19′ transformation occurred when V content was 0.5 at%, above which the B2–B19–B19′ transformation occurred. The B2–B19 transformation was not separated clearly from the B19–B19′ transformation. Thermo-mechanically treated Ti–(45−x)Ni–5Cu–xV alloys showed perfect shape memory effect and transformation hysteresis(ΔT) of Ti–43.5Ni–5.0Cu–1.5V and Ti–43.0Ni–5.0Cu–2.0V alloys was about 9 K which was much smaller than that of a Ti–44.5Ni–5.0Cu–0.5V alloy(23.3 K). More than 90% of superelastic recovery ratio was observed in all specimens and transformation hysteresis (Δσ) of a Ti–44.5Ni–5.0Cu–0.5V alloy was about 70 MPa, which was much larger than that of a Ti–43.0Ni–5.0Cu–2.0V alloy (35 MPa).

  5. Space power subsystem automation technology

    NASA Technical Reports Server (NTRS)

    Graves, J. R. (Compiler)

    1982-01-01

    The technology issues involved in power subsystem automation and the reasonable objectives to be sought in such a program were discussed. The complexities, uncertainties, and alternatives of power subsystem automation, along with the advantages from both an economic and a technological perspective were considered. Whereas most spacecraft power subsystems now use certain automated functions, the idea of complete autonomy for long periods of time is almost inconceivable. Thus, it seems prudent that the technology program for power subsystem automation be based upon a growth scenario which should provide a structured framework of deliberate steps to enable the evolution of space power subsystems from the current practice of limited autonomy to a greater use of automation with each step being justified on a cost/benefit basis. Each accomplishment should move toward the objectives of decreased requirement for ground control, increased system reliability through onboard management, and ultimately lower energy cost through longer life systems that require fewer resources to operate and maintain. This approach seems well-suited to the evolution of more sophisticated algorithms and eventually perhaps even the use of some sort of artificial intelligence. Multi-hundred kilowatt systems of the future will probably require an advanced level of autonomy if they are to be affordable and manageable.

  6. Solar-electric propulsion breadboard thrust subsystem

    NASA Technical Reports Server (NTRS)

    Masek, T. D.

    1972-01-01

    A solar-electric propulsion breadboard thrust subsystem has been designed, built, and tested. A 1500-h test was performed to demonstrate the functional capabilities of the subsystem. Described are the subsystem functions and testing process. The results show that the ground work has been established for development of an engineering model of the thrust subsystem.

  7. Marginal and internal fit of heat pressed versus CAD/CAM fabricated all-ceramic onlays after exposure to thermo-mechanical fatigue

    PubMed Central

    Guess, Petra C.; Vagopoulou, Thaleia; Zhang, Yu; Wolkewitz, Martin; Strub, Joerg R.

    2015-01-01

    Objectives The aim of the study was to evaluate the marginal and internal fit of heat-pressed and CAD/CAM fabricated all-ceramic onlays before and after luting as well as after thermo-mechanical fatigue. Materials and Methods Seventy-two caries-free, extracted human mandibular molars were randomly divided into three groups (n=24/group). All teeth received an onlay preparation with a mesio-occlusal-distal inlay cavity and an occlusal reduction of all cusps. Teeth were restored with heat-pressed IPS-e.max-Press* (IP, *Ivoclar-Vivadent) and Vita-PM9 (VP, Vita-Zahnfabrik) as well as CAD/CAM fabricated IPS-e.max-CAD* (IC, Cerec 3D/InLab/Sirona) all-ceramic materials. After cementation with a dual-polymerizing resin cement (VariolinkII*), all restorations were subjected to mouth-motion fatigue (98N, 1.2 million cycles; 5°C/55°C). Marginal fit discrepancies were examined on epoxy replicas before and after luting as well as after fatigue at 200x magnification. Internal fit was evaluated by multiple sectioning technique. For the statistical analysis, a linear model was fitted with accounting for repeated measurements. Results Adhesive cementation of onlays resulted in significantly increased marginal gap values in all groups, whereas thermo-mechanical fatigue had no effect. Marginal gap values of all test groups were equal after fatigue exposure. Internal discrepancies of CAD/CAM fabricated restorations were significantly higher than both press manufactured onlays. Conclusions Mean marginal gap values of the investigated onlays before and after luting as well as after fatigue were within the clinically acceptable range. Marginal fit was not affected by the investigated heat-press versus CAD/CAM fabrication technique. Press fabrication resulted in a superior internal fit of onlays as compared to the CAD/CAM technique. Clinical Relevance Clinical requirements of 100 μm for marginal fit were fulfilled by the heat-press as well as by the CAD/CAM fabricated all-ceramic onlays

  8. Spacelab data management subsystem phase B study

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The Spacelab data management system is described. The data management subsystem (DMS) integrates the avionics equipment into an operational system by providing the computations, logic, signal flow, and interfaces needed to effectively command, control, monitor, and check out the experiment and subsystem hardware. Also, the DMS collects/retrieves experiment data and other information by recording and by command of the data relay link to ground. The major elements of the DMS are the computer subsystem, data acquisition and distribution subsystem, controls and display subsystem, onboard checkout subsystem, and software. The results of the DMS portion of the Spacelab Phase B Concept Definition Study are analyzed.

  9. High energy flux thermo-mechanical test of 1D-carbon-carbon fibre composite prototypes for the SPIDER diagnostic calorimeter.

    PubMed

    De Muri, M; Cavallin, T; Pasqualotto, R; Dalla Palma, M; Cervaro, V; Fasolo, D; Franchin, L; Tollin, M; Greuner, H; Böswirth, B; Serianni, G

    2014-02-01

    Operation of the thermonuclear fusion experiment ITER requires additional heating via injection of neutral beams from accelerated negative ions. In the SPIDER test facility, under construction in Padova, the production of negative ions will be studied and optimised. STRIKE (Short-Time Retractable Instrumented Kalorimeter Experiment) is a diagnostic used to characterise the SPIDER beam during short pulse operation (several seconds) to verify if the beam meets the ITER requirements about the maximum allowed beam non-uniformity (below ±10%). The major components of STRIKE are 16 1D-CFC (Carbon-Carbon Fibre Composite) tiles, observed at the rear side by a thermal camera. This contribution gives an overview of some tests under high energy particle flux, aimed at verifying the thermo-mechanical behaviour of several CFC prototype tiles. The tests were performed in the GLADIS facility at IPP (Max-Plank-Institut für Plasmaphysik), Garching. Dedicated linear and nonlinear simulations were carried out to interpret the experiments and a comparison of the experimental data with the simulation results is presented. The results of some morphological and structural studies on the material after exposure to the GLADIS beam are also given. PMID:24593452

  10. A thermo-mechanical correlation with driving forces for hcp martensite and twin formations in the Fe–Mn–C system exhibiting multicomposition sets

    SciTech Connect

    Nakano, Jinichiro

    2013-03-15

    Thermodynamic properties of the Fe-Mn-C system were investigated by using an analytical model constructed by a CALPHAD approach. Stacking fault energy (SFE) of the fcc structure with respect to the hcp phase was always constant at T0, independent of composition and temperature when the other related parameters were assumed to be constant. Experimental limits for the thermal hcp formation and the mechanical (deformation-induced) hcp formation were separated by the SFE at T0. The driving force for the fcc to hcp transition, defined as a dimensionless value –dGm/(RT), was determined in the presence of Fe-rich and Mn-rich composition sets in each phase. Carbon tended to partition to the Mn-rich phase rather than to the Fe-rich phase for the studied compositions. The obtained results revealed a thermo-mechanical correlation with empirical yield strength, maximum true stress and maximum true strain. The proportionality between thermodynamics and mechanical properties is discussed.

  11. Bi-directional homogenization equivalent modeling for the prediction of thermo-mechanical properties of a multi-layered printed circuit board (PCB)

    NASA Astrophysics Data System (ADS)

    Joo, Sung-Jun; Park, Buhm; Kim, Do-Hyoung; Kwak, Dong-Ok; Park, Junhong; Kim, Hak-Sung

    2016-04-01

    Warpage of multi-layered printed circuit boards (PCB) during the reflow process is a serious problem which affects the reliability of solder ball connections between the PCB and the mounted semi-conductor packages in electronic devices. It is essential to predict the warpage of the PCB accurately; however, the complicated copper patterns in multi-layered PCBs render a full modeling analysis impossible due to the excessive computing time required. To overcome this problem, we have developed analytical equations of three Cu patterns (line, square, and grid) for the application of thermo-mechanical properties simply by equivalent modeling of Cu patterns. In the proposed equations, the effect of thermo-viscoelastic properties as well as the influence of surrounding layers such as woven glass fabric/BT (bismaleimide triazine), composite laminate (BT core), and photoimageable solder resist (PSR) were considered. To verify the developed equations, vibration tests based on the wave propagation approach were performed at various temperatures. Good agreement was observed between the equivalent model and the experimental results.

  12. Laccase-Catalyzed Surface Modification of Thermo-Mechanical Pulp (TMP) for the Production of Wood Fiber Insulation Boards Using Industrial Process Water

    PubMed Central

    Schubert, Mark; Ruedin, Pascal; Civardi, Chiara; Richter, Michael; Hach, André; Christen, Herbert

    2015-01-01

    Low-density wood fiber insulation boards are traditionally manufactured in a wet process using a closed water circuit (process water). The water of these industrial processes contains natural phenolic extractives, aside from small amounts of admixtures (e.g., binders and paraffin). The suitability of two fungal laccases and one bacterial laccase was determined by biochemical characterization considering stability and substrate spectra. In a series of laboratory scale experiments, the selected commercial laccase from Myceliophtora thermophila was used to catalyze the surface modification of thermo-mechanical pulp (TMP) using process water. The laccase catalyzed the covalent binding of the phenolic compounds of the process water onto the wood fiber surface and led to change of the surface chemistry directly via crosslinking of lignin moieties. Although a complete substitution of the binder was not accomplished by laccase, the combined use of laccase and latex significantly improved the mechanical strength properties of wood fiber boards. The enzymatically-treated TMP showed better interactions with the synthetic binder, as shown by FTIR-analysis. Moreover, the enzyme is extensively stable in the process water and the approach requires no fresh water as well as no cost-intensive mediator. By applying a second-order polynomial model in combination with the genetic algorithm (GA), the required amount of laccase and synthetic latex could be optimized enabling the reduction of the binder by 40%. PMID:26046652

  13. Investigation of the thermo-mechanical behavior of neutron-irradiated Fe-Cr alloys by self-consistent plasticity theory

    NASA Astrophysics Data System (ADS)

    Xiao, Xiazi; Terentyev, Dmitry; Yu, Long; Bakaev, A.; Jin, Zhaohui; Duan, Huiling

    2016-08-01

    The thermo-mechanical behavior of non-irradiated (at 223 K, 302 K and 573 K) and neutron irradiated (at 573 K) Fe-2.5Cr, Fe-5Cr and Fe-9Cr alloys is studied by a self-consistent plasticity theory, which consists of constitutive equations describing the contribution of radiation defects at grain level, and the elastic-viscoplastic self-consistent method to obtain polycrystalline behaviors. Attention is paid to two types of radiation-induced defects: interstitial dislocation loops and solute rich clusters, which are believed to be the main sources of hardening in Fe-Cr alloys at medium irradiation doses. Both the hardening mechanism and microstructural evolution are investigated by using available experimental data on microstructures, and implementing hardening rules derived from atomistic data. Good agreement with experimental data is achieved for both the yield stress and strain hardening of non-irradiated and irradiated Fe-Cr alloys by treating dislocation loops as strong thermally activated obstacles and solute rich clusters as weak shearable ones.

  14. A semi analytical method for electro-thermo-mechanical nonlinear vibration analysis of nanobeam resting on the Winkler-Pasternak foundations with general elastic boundary conditions

    NASA Astrophysics Data System (ADS)

    Zarepour, Misagh; Amirhosein Hosseini, Seyed

    2016-08-01

    This study presents an examination of nonlinear free vibration of a nanobeam under electro-thermo-mechanical loading with elastic medium and various boundary conditions, especially the elastic boundary condition. The nanobeam is modeled as an Euler–Bernoulli beam. The von Kármán strain-displacement relationship together with Hamilton’s principle and Eringen’s theory are employed to derive equations of motion. The nonlinear free vibration frequency is obtained for simply supported (S-S) and elastic supported (E-E) boundary conditions. E-E boundary condition is a general and actual form of boundary conditions and it is chosen because of more realistic behavior. By applying the differential transform method (DTM), the nanobeam’s natural frequencies can be easily obtained for the two different boundary conditions mentioned above. Performing a precise study led to investigation of the influences of nonlocal parameter, temperature change, spring constants (either for elastic medium or boundary condition) and imposed electric potential on the nonlinear free vibration characteristics of nanobeam. The results for S-S and E-E nanobeams are compared with each other. In order to validate the results, some comparisons are presented between DTM results and open literature to show the accuracy of this new approach. It has been discovered that DTM solves the equations with minimum calculation cost.

  15. A thermo-mechanical correlation with driving forces for hcp martensite and twin formations in the Fe–Mn–C system exhibiting multicomposition sets

    DOE PAGESBeta

    Nakano, Jinichiro

    2013-03-15

    Thermodynamic properties of the Fe-Mn-C system were investigated by using an analytical model constructed by a CALPHAD approach. Stacking fault energy (SFE) of the fcc structure with respect to the hcp phase was always constant at T0, independent of composition and temperature when the other related parameters were assumed to be constant. Experimental limits for the thermal hcp formation and the mechanical (deformation-induced) hcp formation were separated by the SFE at T0. The driving force for the fcc to hcp transition, defined as a dimensionless value –dGm/(RT), was determined in the presence of Fe-rich and Mn-rich composition sets in eachmore » phase. Carbon tended to partition to the Mn-rich phase rather than to the Fe-rich phase for the studied compositions. The obtained results revealed a thermo-mechanical correlation with empirical yield strength, maximum true stress and maximum true strain. The proportionality between thermodynamics and mechanical properties is discussed.« less

  16. A Semi Analytical Method For Electro-Thermo-Mechanical Nonlinear Vibration Analysis of Nanobeam Resting On the Winkler-Pasternak Foundations With General Elastic Boundary Conditions

    NASA Astrophysics Data System (ADS)

    Zarepour, Misagh; Amirhosein Hosseini, Seyed

    2016-08-01

    This study presents an examination of nonlinear free vibration of a nanobeam under electro-thermo-mechanical loading with elastic medium and various boundary conditions, especially the elastic boundary condition. The nanobeam is modeled as an Euler–Bernoulli beam. The von Kármán strain-displacement relationship together with Hamilton’s principle and Eringen’s theory are employed to derive equations of motion. The nonlinear free vibration frequency is obtained for simply supported (S-S) and elastic supported (E-E) boundary conditions. E-E boundary condition is a general and actual form of boundary conditions and it is chosen because of more realistic behavior. By applying the differential transform method (DTM), the nanobeam’s natural frequencies can be easily obtained for the two different boundary conditions mentioned above. Performing a precise study led to investigation of the influences of nonlocal parameter, temperature change, spring constants (either for elastic medium or boundary condition) and imposed electric potential on the nonlinear free vibration characteristics of nanobeam. The results for S-S and E-E nanobeams are compared with each other. In order to validate the results, some comparisons are presented between DTM results and open literature to show the accuracy of this new approach. It has been discovered that DTM solves the equations with minimum calculation cost.

  17. Laccase-Catalyzed Surface Modification of Thermo-Mechanical Pulp (TMP) for the Production of Wood Fiber Insulation Boards Using Industrial Process Water.

    PubMed

    Schubert, Mark; Ruedin, Pascal; Civardi, Chiara; Richter, Michael; Hach, André; Christen, Herbert

    2015-01-01

    Low-density wood fiber insulation boards are traditionally manufactured in a wet process using a closed water circuit (process water). The water of these industrial processes contains natural phenolic extractives, aside from small amounts of admixtures (e.g., binders and paraffin). The suitability of two fungal laccases and one bacterial laccase was determined by biochemical characterization considering stability and substrate spectra. In a series of laboratory scale experiments, the selected commercial laccase from Myceliophtora thermophila was used to catalyze the surface modification of thermo-mechanical pulp (TMP) using process water. The laccase catalyzed the covalent binding of the phenolic compounds of the process water onto the wood fiber surface and led to change of the surface chemistry directly via crosslinking of lignin moieties. Although a complete substitution of the binder was not accomplished by laccase, the combined use of laccase and latex significantly improved the mechanical strength properties of wood fiber boards. The enzymatically-treated TMP showed better interactions with the synthetic binder, as shown by FTIR-analysis. Moreover, the enzyme is extensively stable in the process water and the approach requires no fresh water as well as no cost-intensive mediator. By applying a second-order polynomial model in combination with the genetic algorithm (GA), the required amount of laccase and synthetic latex could be optimized enabling the reduction of the binder by 40%. PMID:26046652

  18. High energy flux thermo-mechanical test of 1D-carbon-carbon fibre composite prototypes for the SPIDER diagnostic calorimeter

    SciTech Connect

    De Muri, M. Pasqualotto, R.; Dalla Palma, M.; Cervaro, V.; Fasolo, D.; Franchin, L.; Tollin, M.; Serianni, G.; Cavallin, T.; Greuner, H.; Böswirth, B.

    2014-02-15

    Operation of the thermonuclear fusion experiment ITER requires additional heating via injection of neutral beams from accelerated negative ions. In the SPIDER test facility, under construction in Padova, the production of negative ions will be studied and optimised. STRIKE (Short-Time Retractable Instrumented Kalorimeter Experiment) is a diagnostic used to characterise the SPIDER beam during short pulse operation (several seconds) to verify if the beam meets the ITER requirements about the maximum allowed beam non-uniformity (below ±10%). The major components of STRIKE are 16 1D-CFC (Carbon-Carbon Fibre Composite) tiles, observed at the rear side by a thermal camera. This contribution gives an overview of some tests under high energy particle flux, aimed at verifying the thermo-mechanical behaviour of several CFC prototype tiles. The tests were performed in the GLADIS facility at IPP (Max-Plank-Institut für Plasmaphysik), Garching. Dedicated linear and nonlinear simulations were carried out to interpret the experiments and a comparison of the experimental data with the simulation results is presented. The results of some morphological and structural studies on the material after exposure to the GLADIS beam are also given.

  19. Life support subsystem monitoring instrumentation

    NASA Technical Reports Server (NTRS)

    Powell, J. D.; Kostell, G. D.

    1974-01-01

    The recognition of the need for instrumentation in manned spacecraft life-support subsystems has increased significantly over the past several years. Of the required control and monitoring instrumentation, this paper will focus on the monitoring instrumentation as applied to life-support subsystems. The initial approach used independent sensors, independent sensor signal conditioning circuitry, and independent logic circuitry to provide shutdown protection only. This monitoring system was replaced with a coordinated series of printed circuit cards, each of which contains all the electronics to service one sensor and provide performance trend information, fault detection and isolation information, and shutdown protection. Finally, a review of sensor and instrumentation problems is presented, and the requirement for sensors with built-in signal conditioning and provisions for in situ calibration is discussed.

  20. Catalytic distillation water recovery subsystem

    NASA Technical Reports Server (NTRS)

    Budininkas, P.; Rasouli, F.

    1985-01-01

    An integrated engineering breadboard subsystem for the recovery of potable water from untreated urine based on the vapor phase catalytic ammonia removal was designed, fabricated and tested. Unlike other evaporative methods, this process catalytically oxidizes ammonia and volatile hydrocarbons vaporizing with water to innocuous products; therefore, no pretreatment of urine is required. Since the subsystem is fabricated from commercially available components, its volume, weight and power requirements are not optimized; however, it is suitable for zero-g operation. The testing program consists of parametric tests, one month of daily tests and a continuous test of 168 hours duration. The recovered water is clear, odorless, low in ammonia and organic carbon, and requires only an adjustment of its pH to meet potable water standards. The obtained data indicate that the vapor phase catalytic ammonia removal process, if further developed, would also be competitive with other water recovery systems in weight, volume and power requirements.

  1. Tracking subsystem test requirements survey

    NASA Technical Reports Server (NTRS)

    Orr, D. H.; Tatosian, C. G.; Bynum, M. C.; Zook, A. W.

    1975-01-01

    A survey of the test and checkout requirements of the tracking portion of the communications and tracking subsystem was performed to evaluate adequacy of planned tests and test requirement documents. Emphasis is placed on identifying test completeness, duplications, and omissions. Items that may save time, aid in testing, and present a more complete integrated test program are also noted. The results of this survey are summarized.

  2. SP-100 Reactor Subsystem Development

    NASA Astrophysics Data System (ADS)

    Demuth, Scott F.

    1994-07-01

    The SP-100 reactor subsystem consists of the pressure vessel, vessel internals, and fuel elements. Type A (standard) Nb-1Zr and rhenium materials development efforts related to fabrication of the vessel, vessel internals, and fuel cladding/liner have been completed. Type A and Type C (PWC-11) Nb-1Zr loop fabrication has been successfully demonstrated by prototypic testing with flowing lithium at 1350 K for 1500 hr. Development of UN fuel has been completed, and the performance validated by irradiation testing to the full life (7 yr. full power) burnup of 6 atom %. Neutronic and hydraulic core performance have been validated by engineering mockup critical experiments in the Zero Power Physics Reactor at Argonne National Laboratory, and detailed core hydraulic flow testing with water. Essentially all feasibility issues have been settled for the full life SP-100 reactor subsystem. Remaining SP-100 reactor subsystem development efforts are focused on further reducing mass by the use of Type C (PWC-11) Nb-1Zr rather than Type A, and demonstrating fuel life for beyond full life to perhaps 9 atom % burnup.

  3. The Human Subsystem - Definition and Integration

    NASA Technical Reports Server (NTRS)

    vonBengston, Kristian; Twyford, Evan

    2007-01-01

    This paper will discuss the use of the human subsystem in development phases of human space flight. Any space mission has clearly defined subsystems, managed by experts attached to these. Clearly defined subsystems and correct use provide easier and more efficient development for each independent subsystem and for the relation between these subsystems. Furthermore, this paper will argue that a defined subsystem related to humans in space has not always been clearly present, and that correct implementation is perhaps missing, based on experience and survey data. Finally, the authors will discuss why the human subsystem has not been fully integrated, why it must be a mandatory part of the programming, a re-definition of the human subsystem, and suggestions of methods to improve the integration of human factors in the development.

  4. Matrix structure evolution and thermo-mechanical properties of carbon fiber-reinforced Al{sub 2}O{sub 3}-SiC-C castable composites

    SciTech Connect

    Li, Xiangcheng Li, Yaxiong; Chen, Liufang; Zhu, Boquan

    2015-01-15

    Highlights: • Carbon fibers are formed in Al{sub 2}O{sub 3}-SiC-C castable composites under the action of nano Ni. • Starting growth temperature is 900 °C and growth mechanism agrees with V–S model. • The high temperature strength of composites can be increased by above 40%. • The thermal shock resistance can be enhanced by above 20%. - Abstract: The spalling and corrosion during the thermal cycles are the main causes of the damages observed in Al{sub 2}O{sub 3}-SiC-C castable composites that are used in molten-iron system. Using the catalyst of nano Ni and ball pitch in the matrix, Al{sub 2}O{sub 3}-SiC-C castable composites were prepared with the anti-oxidant addition of silicon. The results indicate that the high temperature of the Al{sub 2}O{sub 3}-SiC-C castable composites can be increased by above 42%, and the thermal shock resistance can be enhanced by above 20% because the ball pitch is carbonized and releases C{sub x}H{sub y} vapor, which can be pyrolized to carbon atoms and subsequently deposited into carbon fibers under the catalyst action. The starting temperature of carbon fiber growth is approximately 900 °C, and their diameter and aspect ratio can increase with the rising temperature. The in-situ generation of carbon fibers in Al{sub 2}O{sub 3}-SiC-C castable composites can significantly improve the fibers’ thermo-mechanical properties.

  5. Thermal, Mechanical and Thermo-Mechanical Assessment of the Rock Mass Surrounding SKB's Prototype Repository at Äspö HRL

    NASA Astrophysics Data System (ADS)

    Lönnqvist, Margareta; Hökmark, Harald

    2016-04-01

    The Prototype Repository (PR) was a field test of six, electrically heated, full-scale waste containers resembling the key component of a KBS-3 nuclear waste repository. The design and heat load was similar to the proposed repository at Forsmark, Sweden. In this paper, the thermal, mechanical and thermo-mechanical response of the PR host rock to excavation and to the subsequent heating is assessed. The assessment is carried out using three-dimensional models (numerical and analytical) in combination with monitoring data and visual observations from the excavations. Certain measurements and observations agree well with results from the models. These include temperature measurements during the heating phase. Additional measurements include patterns of low-magnitude acoustic emission events around the deposition holes tracked during the excavation. The spatial distribution of these events coincide with regions of modelled high compressive stresses. Models with a simple fracture network, consisting of planar disks with laboratory-scale properties, appear to give upper bound estimates of the stress disturbances caused by a real fracture network. The magnitude of the modelled stresses around the deposition hole is typically below the spalling strength. The lack of any significant or systematic occurrence of spalling in the deposition hole walls supports the modelling results. Several instruments installed at different positions to monitor stress change, strain and deformation malfunctioned during the nearly 8-year-long monitoring period. Despite this, there is ample evidence to support the overall conclusion that the modelling results and observations are in sufficient agreement to strengthen the confidence in the modelling approach.

  6. Technology advancement of an oxygen generation subsystem

    NASA Technical Reports Server (NTRS)

    Lee, M. K.; Burke, K. A.; Schubert, F. H.; Wynveen, R. A.

    1979-01-01

    An oxygen generation subsystem based on water electrolysis was developed and tested to further advance the concept and technology of the spacecraft air revitalization system. Emphasis was placed on demonstrating the subsystem integration concept and hardware maturity at a subsystem level. The integration concept of the air revitalization system was found to be feasible. Hardware and technology of the oxygen generation subsystem was demonstrated to be close to the preprototype level. Continued development of the oxygen generation technology is recommended to further reduce the total weight penalties of the oxygen generation subsystem through optimization.

  7. Controlled Thermo-Mechanical Processing

    SciTech Connect

    2005-09-01

    The CTMP technology has the potential for widespread application in all major sectors of the domestic tube and pipe industry; two of the largest sectors are seamless mechanical tubing and seamless oil country tubular goods. It has been proven for the spheroidized annealing heat cycle for through-hardened steels and has led to the development of a recipe for automotive gear steels. Potential applications also exist in the smaller sectors of seamless line pipe, pressure tubing, and stainless tubing. The technology could also apply to non-ferrous metal industries, such as titanium.

  8. TOPS attitude propulsion subsystem technology

    NASA Technical Reports Server (NTRS)

    Moynihan, P. I.

    1971-01-01

    The thermoelectric outer-planet spacecraft (TOPS) attitude propulsion subsystem effort is summarized. It includes the tradeoff rationale that went into the selection of anhydrous hydrazine as the propellant, and a brief description of three types of 0.445-N (100-mlbf) thrusters that were purchased for in-house evaluation. A discussion is also included of the 0.2224-N (50-mlbf)-developed thrusters and their integration with a portable, completely enclosed, propulsion module that was designed and developed to support the TOPS single-axis attitude control tests in the celestarium.

  9. FLPP NGL Structural Subsystems Activity

    NASA Astrophysics Data System (ADS)

    Jaredson, D.; Ramusat, G.; Appel, S.; Cardone, T.; Persson, J.; Baiocco, P.; Lavelle, F.; Bouilly, Th.

    2012-07-01

    The ESA Future Launchers Preparatory Programme (FLPP) is the basis for new paradigms, investigating the key elements, logic and roadmaps to prepare the development of the safe, reliable and low cost next European Launch Vehicle (LV) for access to space (dubbed NGL - Next Generation LV), with an initial operational capability mid-next decade. In addition to carry cargo to conventional GTO or SSO, the European NGL has to be flexible enough to cope with new pioneering institutional missions as well as the evolving commercial payloads market. This achievement is broached studying three main areas relevant to ELVs: System concepts, Propulsion and Core Technology During the preliminary design activity, a number of design alternatives concerning NGL main structural subsystems have been investigated. Technology is one of the ways to meet the NGL challenges to either improve the performances or to reduce the cost or both. The relevant requirements allow to steer a ‘top-down’ approach for their conception and to propose the most effective technologies. Furthermore, all these technology developments represent a significant ‘bottom-up’ approach investment and concern a large range of activities. The structural subsystems portfolio of the FLPP ‘Core Technology’ activity encompasses major cutting-edge challenges for maturation of the various subsystems leading to reduce overall structural mass, increasing structural margins for robustness, metallic and composite containment of cryogenic propellants, significantly reducing fabrication and operations cost, etc. to derive performing upper and booster stages. Application of concurrent engineering methods will allow developments of performing technology demonstrators in terms of need, demonstration objective, size and cost yielding to safe, low-risk technical approaches for a future development. Potential ability of these advanced structural LV technologies to satisfy the system requirements of the NGL and their current

  10. Preprototype nitrogen supply subsystem development

    NASA Technical Reports Server (NTRS)

    Heppner, D. B.; Fort, J. H.; Schubert, F. H.

    1982-01-01

    The design and development of a test stand for the Nitrogen Generation Module (NGM) and a series of tests which verified its operation and performance capability are described. Over 900 hours of parametric testing were achieved. The results from this testing were then used to design an advanced NGM and a self contained, preprototype Nitrogen Supply Subsystem. The NGM consists of three major components: nitrogen generation module, pressure controller and hydrazine storage tank and ancillary components. The most important improvement is the elimination of all sealing surfaces, achieved with a total welded or brazed construction. Additionally, performance was improved by increasing hydrogen separating capability by 20% with no increase in overall packaging size.

  11. Vessel support subsystem design description. Revision 1

    SciTech Connect

    Perry, R.A.; Mehta, D.D.

    1987-07-01

    The Vessel Support Subsystem is one of three subsystems comprising the Vessel System of the Modular High Temperature Gas-Cooled Reactor 4 x 350 MW(t) Plant. The design of this subsystem has been developed by means of the Integrated Approach. This document establishes the functions and system design requirements of the Vessel Support Subsystem from the Functional Analysis, and includes institutional requirements from the Overall Plant Design Specification and the Vessel System Design Description. A description of the subsystem design which satisfies these requirements is presented. Lower-tier requirements at the subsystem level are next defined for the component design. This document also includes information on aspects of subsystem construction, operation, maintenance, and decommissioning.

  12. Preprototype independent air revitalization subsystem

    NASA Technical Reports Server (NTRS)

    Schubert, F. H.; Hallick, T. M.; Woods, R. R.

    1982-01-01

    The performance and maturity of a preprototype, three-person capacity, automatically controlled and monitored, self-contained independent air revitalization subsystem were evaluated. The subsystem maintains the cabin partial pressure of oxygen at 22 kPa (3.2 psia) and that of carbon dioxide at 400 Pa (3 mm Hg) over a wide range of cabin air relative humidity conditions. Consumption of water vapor by the water vapor electrolysis module also provides partial humidity control of the cabin environment. During operation, the average carbon dioxide removal efficiency at baseline conditions remained constant throughout the test at 84%. The average electrochemical depolarized concentrator cell voltage at the end of the parametric/endurance test was 0.41 V, representing a very slowly decreasing average cell voltage. The average water vapor electrolysis cell voltage increased only at a rate of 20 mu/h from the initial level of 1.67 V to the final level of 1.69 V at conclusion of the testing.

  13. Evolution of crustal stress, pressure and temperature around shear zones during orogenic wedge formation: a 2D thermo-mechanical numerical study

    NASA Astrophysics Data System (ADS)

    Markus Schmalholz, Stefan; Jaquet, Yoann

    2016-04-01

    We study the formation of an orogenic wedge during lithospheric shortening with 2D numerical simulations. We consider a viscoelastoplastic rheology, thermo-mechanical coupling by shear heating and temperature-dependent viscosities, gravity and erosion. In the initial model configuration there is either a lateral temperature variation at the model base or a lateral variation in crustal thickness to generate slight stress variations during lithospheric shortening. These stress variations can trigger the formation of shear zones which are caused by thermal softening associated with shear heating. We do not apply any kind of strain softening, such as reduction of friction angle with progressive plastic strain. The first major shear zone that appears during shortening crosscuts the entire crust and initiates the asymmetric subduction/underthrusting of mainly the mechanically strong lower crust. After some deformation, the first shear zone in the upper crust is abandoned, the deformation propagates towards the foreland and a new shear zone forms only in the upper crust. The shear zone propagation occurs several times where new shear zones form in the upper crust and the mechanically strong top of the lower crust acts as detachment horizon. We calculate the magnitudes of the maximal and minimal principal stresses and of the mean stress (or dynamic pressure), and we record also the temperature for several marker points in the upper and lower crust. We analyse the evolution of stresses and temperature with burial depth and time. Deviatoric stresses (half the differential stress) in the upper crust are up to 200 MPa and associated shear heating in shear zones ranges between 40 - 80 °C. Lower crustal rocks remain either at the base of the orogenic wedge at depths of around 50 km or are subducted to depths of up to 120 km, depending on their position when the first shear zone formed. Largest deviatotric stresses in the strong part of the lower crust are about 1000 MPa and

  14. A thermo-mechanical numerical scenario aiming at reproducing the metamorphic record of high-P rocks in the Palaeoproterozoic Eburnean orogeny.

    NASA Astrophysics Data System (ADS)

    Gerbault, Muriel; Ganne, Jerome; Baratoux, Lenka; Dioh, Edmond; de Andrade, Vincent; Block, Sylvain; Perrouty, Stephane; Jessell, Marc

    2013-04-01

    We test a scenario of the evolution of the Palaeoproterozoic Eburnean event characterising the Birimian Province (2.2-2.0 Ga, Western African Craton). A compilation of field data and petrological modeling indicates that an early thermal regime (M1, <10-15°/km) would have produced high-P greenschist to blueschist metamorphism assemblages, that most likely originated in thick sedimentary basins (depth>=20 km), and which would have formed above an original Birimian oceanic crust (possibly preaccreted forearc-backarcs systems). These assemblages record elevated pressures (P> 6-8 Kb) and are found in the thermal aureoles of CaO-poor granitoids. A second warmer, dominant geothermal gradient M2a (20-30°C/km) is found superimposed on M1, associated to greenschist-amphibolite metamorphic assemblages of moderate- to high-pressure rocks. We suggest that these rocks underwent exhumation processes in close association with continued regional shortening and granitoid intrusions. A thermo-mechanical model is proposed here for the Birimian crust, in which we choose an initial setting of oceanic arc resistant layer underlain by a layer of buoyant granitoids (CaO-rich TTGs). At the center of the model, this layer is itself overlain by a tectonically paired, mechanically weak basin several hundreds of kilometers wide (forearc-backarc system ?). Under applied compression, the model reproduces a mechanism of burial and distributed large-scale folding of this juvenile crust. As the oceanic arc and TTGs layers fold below the overlying hydrated sediments, their hinges deepen and they reach appropriate PT conditions to start melting and transform into a dominantly buoyant (CaO-poor) melt product, of lower viscosity and density (by ~5%). This newly formed material ascends and migrate laterally towards the upper parts of the buckle folds, and then pursues its ascension through the weak overlying sediments, within about 50 Myrs. This spatially periodical and "diapiric" mode of exhumation is

  15. Comparing a thermo-mechanical Weichselian Ice Sheet reconstruction to reconstructions based on the sea level equation: aspects of ice configurations and glacial isostatic adjustment

    NASA Astrophysics Data System (ADS)

    Schmidt, P.; Lund, B.; Näslund, J.-O.; Fastook, J.

    2014-05-01

    In this study we compare a recent reconstruction of the Weichselian Ice Sheet as simulated by the University of Maine ice sheet model (UMISM) to two reconstructions commonly used in glacial isostatic adjustment (GIA) modelling: ICE-5G and ANU (Australian National University, also known as RSES). The UMISM reconstruction is carried out on a regional scale based on thermo-mechanical modelling, whereas ANU and ICE-5G are global models based on the sea level equation. The three models of the Weichselian Ice Sheet are compared directly in terms of ice volume, extent and thickness, as well as in terms of predicted glacial isostatic adjustment in Fennoscandia. The three reconstructions display significant differences. Whereas UMISM and ANU includes phases of pronounced advance and retreat prior to the last glacial maximum (LGM), the thickness and areal extent of the ICE-5G ice sheet is more or less constant up until the LGM. During the post-LGM deglaciation phase ANU and ICE-5G melt relatively uniformly over the entire ice sheet in contrast to UMISM, which melts preferentially from the edges, thus reflecting the fundamental difference in the reconstruction scheme. We find that all three reconstructions fit the present-day uplift rates over Fennoscandia equally well, albeit with different optimal earth model parameters. Given identical earth models, ICE-5G predicts the fastest present-day uplift rates, and ANU the slowest. Moreover, only for ANU can a unique best-fit model be determined. For UMISM and ICE-5G there is a range of earth models that can reproduce the present-day uplift rates equally well. This is understood from the higher present-day uplift rates predicted by ICE-5G and UMISM, which result in bifurcations in the best-fit upper- and lower-mantle viscosities. We study the areal distributions of present-day residual surface velocities in Fennoscandia and show that all three reconstructions generally over-predict velocities in southwestern Fennoscandia and that

  16. Cassini Mission Sequence Subsystem (MSS)

    NASA Technical Reports Server (NTRS)

    Alland, Robert

    2011-01-01

    This paper describes my work with the Cassini Mission Sequence Subsystem (MSS) team during the summer of 2011. It gives some background on the motivation for this project and describes the expected benefit to the Cassini program. It then introduces the two tasks that I worked on - an automatic system auditing tool and a series of corrections to the Cassini Sequence Generator (SEQ_GEN) - and the specific objectives these tasks were to accomplish. Next, it details the approach I took to meet these objectives and the results of this approach, followed by a discussion of how the outcome of the project compares with my initial expectations. The paper concludes with a summary of my experience working on this project, lists what the next steps are, and acknowledges the help of my Cassini colleagues.

  17. Keck adaptive optics: control subsystem

    SciTech Connect

    Brase, J.M.; An, J.; Avicola, K.

    1996-03-08

    Adaptive optics on the Keck 10 meter telescope will provide an unprecedented level of capability in high resolution ground based astronomical imaging. The system is designed to provide near diffraction limited imaging performance with Strehl {gt} 0.3 n median Keck seeing of r0 = 25 cm, T =10 msec at 500 nm wavelength. The system will be equipped with a 20 watt sodium laser guide star to provide nearly full sky coverage. The wavefront control subsystem is responsible for wavefront sensing and the control of the tip-tilt and deformable mirrors which actively correct atmospheric turbulence. The spatial sampling interval for the wavefront sensor and deformable mirror is de=0.56 m which gives us 349 actuators and 244 subapertures. This paper summarizes the wavefront control system and discusses particular issues in designing a wavefront controller for the Keck telescope.

  18. FUSE satellite electrical power subsystem

    SciTech Connect

    Roufberg, L.; Noah, K.

    1998-07-01

    The Far Ultraviolet Spectroscopic Explorer (FUSE) satellite will be placed into a low earth orbit to investigate astrophysical processes related to the formation and development of the early universe. The FUSE satellite is considered a pathfinder for NASA's Mid-Class Explorers (MIDEX). To reduce mission cost and development time while delivering quality science, NASA has enforced strict cost caps with a clear definition of high-level science objectives. As a result, a significant design driver for the electrical power subsystem (EPS) was to minimize cost. The FUSE EPS is a direct energy transfer, unregulated bus architecture, with batteries directly on the bus and solar array power limted by pulse-width-modulated shunt regulators. The power subsystem electronics (PSE) contains circuitry to control battery charging, provide power to the loads, and provide fault protection. The electronics is based on the PSE which Orbital (formerly, Fairchild Space) designed and built for NASA/GSFC's XTE spacecraft. However, the FUSE PSE design incorporates a number of unique features to meet the mission requirements. To minimize size of the solar panels due to stowed attachment constraints, GaAs/Ge solar cells were selected. This is the first time this type of large area, thinned solar cell with integral bypass diodes are being used for a NASA LEO mission. The solar panels support a satellite load power of 520W. Nickel Cadmium (NiCd) batteries are used which are identical to the RADARSAT-I design, except for different temperature sensors. This is the first mission for which Orbital is using SAFT NiCd batteries. The spacecraft bus, including the EPS, has successfully completed environmental testing and has been delivered for instrument integration. Tradeoffs involved in designing the EPS and selecting components based on the requirements are discussed. Analyses including solar array and battery sizing and energy balance are presented in addition to results from testing the flight

  19. Electrochemical carbon dioxide concentrator subsystem development

    NASA Technical Reports Server (NTRS)

    Heppner, D. B.; Dahlausen, M. J.; Schubert, F. H.

    1983-01-01

    The fabrication of a one-person Electrochemical Depolarized Carbon Dioxide Concentrator subsystem incorporating advanced electrochemical, mechanical, and control and monitor instrumentation concepts is discussed. This subsystem included an advanced liquid cooled unitized core composite cell module and integrated electromechanical components. Over 1800 hours with the subsystem with removal efficiencies between 90%. and 100%; endurance tests with a Fluid Control Assembly which integrates 11 gas handling components of the subsystem; and endurance testing of a coolant control assembly which integrates a coolant pump, diverter valve and a liquid accumulator were completed.

  20. Electronic Components Subsystems and Equipment: a Compilation

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Developments in electronic components, subsystems, and equipment are summarized. Topics discussed include integrated circuit components and techniques, circuit components and techniques, and cables and connectors.

  1. Private quantum subsystems and quasiorthogonal operator algebras

    NASA Astrophysics Data System (ADS)

    Levick, Jeremy; Jochym-O'Connor, Tomas; Kribs, David W.; Laflamme, Raymond; Pereira, Rajesh

    2016-03-01

    We generalize a recently discovered example of a private quantum subsystem to find private subsystems for Abelian subgroups of the n-qubit Pauli group, which exist in the absence of private subspaces. In doing so, we also connect these quantum privacy investigations with the theory of quasiorthogonal operator algebras through the use of tools from group theory and operator theory.

  2. Installation package for the Solaron solar subsystem

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Information that is intended to be a guide for installation, operation, and maintenance of the various solar subsystems is presented. The subsystems consist of the following: collectors, storage, transport (air handler) and controller for heat pump and peak storage. Two prototype residential systems were installed at Akron, Ohio, and Duffield, Virginia.

  3. Mission payloads subsystem description, revision 2

    NASA Technical Reports Server (NTRS)

    Williams, J. M.

    1976-01-01

    The Mission Payloads Subsystem (MPLS) which utilizes a simplified trajectory model to generate a list of missions for the Scheduling Algorithm for Mission Planning and Logistics Evaluation (SAMPLE) program is described. The MPLS is the mechanism that forms the basis of input for the other subsystems of SAMPLE and various post processors.

  4. Apollo experience report: Lunar module instrumentation subsystem

    NASA Technical Reports Server (NTRS)

    Obrien, D. E., III; Woodfill, J. R., IV

    1972-01-01

    The design concepts and philosophies of the lunar module instrumentation subsystem are discussed along with manufacturing and systems integration. The experience gained from the program is discussed, and recommendations are made for making the subsystem more compatible and flexible in system usage. Characteristics of lunar module caution and warning circuits are presented.

  5. The Calipso Thermal Control Subsystem

    NASA Technical Reports Server (NTRS)

    Gasbarre, Joseph F.; Ousley, Wes; Valentini, Marc; Thomas, Jason; Dejoie, Joel

    2007-01-01

    The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) is a joint NASA-CNES mission to study the Earth s cloud and aerosol layers. The satellite is composed of a primary payload (built by Ball Aerospace) and a spacecraft platform bus (PROTEUS, built by Alcatel Alenia Space). The thermal control subsystem (TCS) for the CALIPSO satellite is a passive design utilizing radiators, multi-layer insulation (MLI) blankets, and both operational and survival surface heaters. The most temperature sensitive component within the satellite is the laser system. During thermal vacuum testing of the integrated satellite, the laser system s operational heaters were found to be inadequate in maintaining the lasers required set point. In response, a solution utilizing the laser system s survival heaters to augment the operational heaters was developed with collaboration between NASA, CNES, Ball Aerospace, and Alcatel-Alenia. The CALIPSO satellite launched from Vandenberg Air Force Base in California on April 26th, 2006. Evaluation of both the platform and payload thermal control systems show they are performing as expected and maintaining the critical elements of the satellite within acceptable limits.

  6. ACCESS Sub-system Performance

    NASA Astrophysics Data System (ADS)

    Kaiser, Mary Elizabeth; Morris, Matthew J.; Aldoroty, Lauren Nicole; Godon, David; Pelton, Russell; McCandliss, Stephan R.; Kurucz, Robert L.; Kruk, Jeffrey W.; Rauscher, Bernard J.; Kimble, Randy A.; Wright, Edward L.; Benford, Dominic J.; Gardner, Jonathan P.; Feldman, Paul D.; Moos, H. Warren; Riess, Adam G.; Bohlin, Ralph; Deustua, Susana E.; Dixon, William Van Dyke; Sahnow, David J.; Lampton, Michael; Perlmutter, Saul

    2016-01-01

    ACCESS: Absolute Color Calibration Experiment for Standard Stars is a series of rocket-borne sub-orbital missions and ground-based experiments designed to leverage significant technological advances in detectors, instruments, and the precision of the fundamental laboratory standards used to calibrate these instruments to enable improvements in the precision of the astrophysical flux scale through the transfer of laboratory absolute detector standards from the National Institute of Standards and Technology (NIST) to a network of stellar standards with a calibration accuracy of 1% and a spectral resolving power of 500 across the 0.35 to 1.7 micron bandpass.A cross wavelength calibration of the astrophysical flux scale to this level of precision over this broad a bandpass is relevant for the data used to probe fundamental astrophysical problems such as the SNeIa photometry based measurements used to constrain dark energy theories.We will describe the strategy for achieving this level of precision, the payload and calibration configuration, present sub-system test data, and the status and preliminary performance of the integration and test of the spectrograph and telescope. NASA APRA sounding rocket grant NNX14AH48G supports this work.

  7. Assessing quality across healthcare subsystems in Mexico.

    PubMed

    Puig, Andrea; Pagán, José A; Wong, Rebeca

    2009-01-01

    Recent healthcare reform efforts in Mexico have focused on the need to improve the efficiency and equity of a fragmented healthcare system. In light of these reform initiatives, there is a need to assess whether healthcare subsystems are effective at providing high-quality healthcare to all Mexicans. Nationally representative household survey data from the 2006 Encuesta Nacional de Salud y Nutrición (National Health and Nutrition Survey) were used to assess perceived healthcare quality across different subsystems. Using a sample of 7234 survey respondents, we found evidence of substantial heterogeneity in healthcare quality assessments across healthcare subsystems favoring private providers over social security institutions. These differences across subsystems remained even after adjusting for socioeconomic, demographic, and health factors. Our analysis suggests that improvements in efficiency and equity can be achieved by assessing the factors that contribute to heterogeneity in quality across subsystems. PMID:19305224

  8. Glacial landscape evolution on Hall Peninsula, Baffin Island, since the Last Glacial Maximum: insights into switching glacial dynamics and thermo-mechanical conditions

    NASA Astrophysics Data System (ADS)

    Johnson, C. L.; Ross, M.

    2012-12-01

    channelized zones (GTZ 2) suggests a switch from warm to cold-based conditions over large areas while warm-based conditions prevailed within the channelized flow zone. This record may reflect the transition from LGM (thick warm-based ice) to thinner topographically-controlled ice, with cold-based patches, during early deglaciation. The catchment zones of the channelized system locally extended into the central area of Hall Peninsula (GTZ 3) which is reflected in till dispersal patterns and the striation record. The retreat of the LIS was later marked by southeastward readvances and/or surges (GTZ 4) and short-lived glacial lakes whose location requires ice to be maintained over GTZ 1. Thin cold-based ice remaining over GTZ 1 may explain the preservation of the inferred LGM landscape in that zone during deglacial events. The glacial landscape of Hall Peninsula reflects the effect of a switch from uniform warm-based ice and laterally extensive erosive basal sliding during LGM to a channelized flow during deglaciation and intervening cold-based zones. The change in basal thermo-mechanical conditions and the geometry of the channelized flow system may be precursor controlling factors to the development and shape of post LIS ice caps in this part of the Canadian Arctic.

  9. Ongoing compression triggered exhumation of the orogenic crust in the Variscan Maures-Tanneron Massif, France - Geological arguments and thermo-mechanical tests

    NASA Astrophysics Data System (ADS)

    Gerbault, Muriel; Schneider, Julie; Reverso-Peila, Alexandre; Corsini, Michel

    2016-04-01

    The Maures-Tanneron Massif (MTM), together with Corsica and Sardinia, hosted the South-Eastern Variscan belt and record a continuous evolution from continental collision to exhumation. We present a synthesis of the available geological and geochronogical data that explores the transition from convergence to perpendicular Permean extension in the MTM (at ~ 325 Ma ± 25 My). The migmatitic Internal Zone that composes the Western MTM displays structural clues such as backthrusting and magmatic foliations, and metamorphic data indicating exhumation of deep seated partially molten rocks at an apparent heating rate of 1-2 °C/km/My from ca. 345 Ma to 320 Ma. This suggests vertical advective heat transport during continued N140° convergence (D2 phase). In contrast at the same time, the low grade External zone composing the Eastern part of the MTM recorded exhumation of more conductive patterns at an apparent rate of 0.3-0.6 °C/km/My. It is only from ca. 320 Ma that transcurrent motion dominates in the Internal zone and progressively leaves way to N-S strecthing (D3 phase), indicative of orogenic collapse and extension and in asociation with emplacement of larger volumes of magmatism in the crust. Thermo-mechanical modeling complements this synthesis in order to highlight the conditions under which deep seated HP units could melt and massively start to exhume during maintained convergence (phase D2). Accounting for temperature dependent elasto-visco-plastic rheologies, our models explore the dynamics of an orogenic prism starting from a dis-equilibrated state just after slab break-off or delamination, at ca. 350 Ma. We simulate the development of gravitational instabilities in partially melting crust, a process that is already well known to depend on strain-rate, heat sources and strength layering. In order to reproduce the exhumation patterns of rocks from ~50 km depth over the appropriate time-scale (>20 My) and spatial extent (>100 km), a best fit was obtained with a

  10. Magnitude of long-term non-lithostatic pressure variations in lithospheric processes: insight from thermo-mechanical subduction/collision models

    NASA Astrophysics Data System (ADS)

    Gerya, Taras

    2014-05-01

    On the one hand, the principle of lithostatic pressure is habitually used in metamorphic geology to calculate paleo-depths of metamorphism from mineralogical pressure estimates given by geobarometry. On the other hand, it is obvious that this lithostatic (hydrostatic) pressure principle should only be valid for an ideal case of negligible deviatoric stresses during the long-term development of the entire tectono-metamorphic system - the situation, which newer comes to existence in natural lithospheric processes. The question is therefore not "Do non-lithostatic pressure variations exist?" but " What is the magnitude of long-term non-lithostatic pressure variations in various lithospheric processes, which can be recorded by mineral equilibria of respective metamorphic rocks?". The later question is, in particular, relevant for various types of high-pressure (HP) and ultrahigh-pressure (UHP) rocks, which are often produced in convergent plate boundary settings (e.g., Hacker and Gerya, 2013). This question, can, in particular, be answered with the use of thermo-mechanical models of subduction/collision processes employing realistic P-T-stress-dependent visco-elasto-brittle/plastic rheology of rocks. These models suggest that magnitudes of pressure deviations from lithostatic values can range >50% underpressure to >100% overpressure, mainly in the regions of bending of rheologically strong mantle lithosphere (Burg and Gerya, 2005; Li et al., 2010). In particular, strong undepresures along normal faults forming within outer rise regions of subducting plates can be responsible for downward water suction and deep hydration of oceanic slabs (Faccenda et al., 2009). Weaker HP and UHP rocks of subduction/collision channels are typically subjected to lesser non-lithostatic pressure variations with characteristic magnitudes ranging within 10-20% from the lithostatic values (Burg and Gerya, 2005; Li et al., 2010). The strength of subducted crustal rocks and the degree of

  11. Igneous Cooling Rate constraints on the Accretion of the lower Oceanic Crust in Mid-ocean Ridges: Insights from a new Thermo-mechanical Model

    NASA Astrophysics Data System (ADS)

    Garrido, C. J.; Machetel, P.

    2005-12-01

    We report the results of a new thermo-mechanical model of crustal flow beneath fast spreading mid-ocean ridges to investigate both the effect of deep, near off-axis hydrothermal convection on the thermal structure of the magma chamber and the role of variable number of melt intrusions on the accretion of the oceanic crust. In our model the melt is injected at the center of the axial magma chamber with a 'needle' with adjustable porosity at different depths allowing the simulation of different arrangements of melt injection and supply within the magma chamber. Conversely to previous models, the shape of the magma chamber -defined as the isotherm where 95% solidification of the melt occurs- is not imposed but computed from the steady state reached by the thermal field considering the heat diffusion and advection and the latent heat of crystallization. The motion equation is solved for a temperature and phase dependent viscosity. The thermal diffusivity is also dependent on temperature and depth, with a higher diffusivity in the upper plutonic crust to account for more efficient hydrothermal cooling at these crustal levels. In agreement with previous non-dynamic thermal models, our results show that near, deep off-axis hydrothermal circulation strongly affects the shape of the axial magma by tightening isotherms in the upper half of the plutonic oceanic crust where hydrothermal cooling is more efficient. Different accretion modes have however little effect on the shape of the magma chamber, but result in variable arrangements of flow lines ranging from tent-shape in a single-lens accretion scenario to sub-horizontal in "sheeted-sill" intrusion models. For different intrusion models, we computed the average Igneous Cooling Rates (ICR) of gabbros by dividing the crystallization temperature interval of gabbros by the integrated time, from the initial intrusion to the point where it crossed the 950 °C isotherm where total solidification of gabbro occurs, along individual

  12. Introducing tectonically and thermo-mechanically realistic lithosphere in the models of plume head -lithosphere interactions (PLI) including intra-continental plate boundaries.

    NASA Astrophysics Data System (ADS)

    Guillou-Frottier, L.; Burov, E.; Cloetingh, S.

    2007-12-01

    Plume-Lithosphere Interactions (PLI) in continets have complex topographic and magmatic signatures and are often identified near boundaries between younger plates (e.g., orogenic) and older stable plates (e.g., cratons), which represent important geometrical, thermal and rheological barriers that interact with the emplacement of the plume head (e.g., Archean West Africa, East Africa, Pannonian - Carpathian system). The observable PLI signatures are conditioned by plume dynamics but also by complex rheology and structure of continental lithosphere. We address this problem by considering a new free-surface thermo-mechanical numerical model of PLI with two stratified elasto-viscous-plastic (EVP) continental plates of contrasting age, thickness and structure. The results show that: (1) surface deformation is poly-harmonic and contains smaller wavelengths (50-500 km) than that associated with the plume head (>1000 km). (2) below intra-plate boundaries, plume head flattening is asymmetric, it is blocked from one side by the cold vertical boundary of the older plate, which leads to mechanical decoupling of crust from mantle lithosphere, and to localized faulting at the cratonic margin; (2) the return flow from the plume head results in sub-vertical down-thrusting (delamination) of the lithosphere at the margin, producing sharp vertical cold boundary down to the 400 km depth; (3) plume head flattening and migration towards the younger plate results in concurrent surface extension above the centre of the plume and in compression (pushing), down-thrusting and magmatic events at the cratonic margin (down-thrusting is also produced at the opposite border of the younger plate); these processes may result in continental growth at the "craton side"; (4) topographic signatures of PLI show basin-scale uplifts and subsidences preferentially located at cratonic margins. Negative Rayleigh-Taylor instabilities in the lithosphere above the plume head provide a mechanism for crustal

  13. 2nd & 3rd Generation Vehicle Subsystems

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This paper contains viewgraph presentation on the "2nd & 3rd Generation Vehicle Subsystems" project. The objective behind this project is to design, develop and test advanced avionics, power systems, power control and distribution components and subsystems for insertion into a highly reliable and low-cost system for a Reusable Launch Vehicles (RLV). The project is divided into two sections: 3rd Generation Vehicle Subsystems and 2nd Generation Vehicle Subsystems. The following topics are discussed under the first section, 3rd Generation Vehicle Subsystems: supporting the NASA RLV program; high-performance guidance & control adaptation for future RLVs; Evolvable Hardware (EHW) for 3rd generation avionics description; Scaleable, Fault-tolerant Intelligent Network or X(trans)ducers (SFINIX); advance electric actuation devices and subsystem technology; hybrid power sources and regeneration technology for electric actuators; and intelligent internal thermal control. Topics discussed in the 2nd Generation Vehicle Subsystems program include: design, development and test of a robust, low-maintenance avionics with no active cooling requirements and autonomous rendezvous and docking systems; design and development of a low maintenance, high reliability, intelligent power systems (fuel cells and battery); and design of a low cost, low maintenance high horsepower actuation systems (actuators).

  14. Propulsion subsystem design for KOREASAT spacecraft

    NASA Astrophysics Data System (ADS)

    Chang, Young K.; Kim, Hee D.; Young, M.

    1993-10-01

    This paper describes the functional design and structure of the propulsion subsystem for the KOREASAT spacecraft. The KOREASAT program consists of two geostationary communication satellites for Korea presently scheduled to be launched in April and October 1995. The spacecraft propulsion subsystem consists of a hydrazine monopropellant blowdown reaction control subsystem, a STAR 30E solid apogee kick motor (AKM) and associated electronics and electrical hardware. The propulsion subsystem for KOREASAT provides the propulsive force and torque required for attitude and orbit attainment and maintenance. The thrusters used on the propulsion subsystem are 12 conventional catalytic decomposition rocket engine assemblies (REAs) with 0.9 N (0.2 lbf) thrust, and four electrothermal hydrazine thrusters (EHTs) with 0.4 N (0.1 Ibf) thrust. REAs are operated in steady-state mode or pulsed mode. EHTs are utilized only for north/south stationkeeping in steady-state mode operation, with limitation of its use during eclipse and eclipse season to conserve power. The basic functions and design requirements for propulsion mechanical and electrical components are also described. The analyses required to evaluate the propulsion subsystem performance are briefly mentioned. Propulsion component and subsystem testing are described.

  15. Intelligent subsystem interface for modular hardware system

    NASA Technical Reports Server (NTRS)

    Krening, Douglas N. (Inventor); Lannan, Gregory B. (Inventor); Schneiderwind, Michael J. (Inventor); Schneiderwind, Robert A. (Inventor); Caffrey, Robert T. (Inventor)

    2000-01-01

    A single chip application specific integrated circuit (ASIC) which provides a flexible, modular interface between a subsystem and a standard system bus. The ASIC includes a microcontroller/microprocessor, a serial interface for connection to the bus, and a variety of communications interface devices available for coupling to the subsystem. A three-bus architecture, utilizing arbitration, provides connectivity within the ASIC and between the ASIC and the subsystem. The communication interface devices include UART (serial), parallel, analog, and external device interface utilizing bus connections paired with device select signals. A low power (sleep) mode is provided as is a processor disable option.

  16. Subsystem design package for Solar II collector

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The requirements for the design and performance of the Solar 2 Collector Subsystem developed for use in solar heating of single family residences and mobile homes are presented. Installation drawings are included.

  17. Goddard trajectory determination subsystem: Mathematical specifications

    NASA Technical Reports Server (NTRS)

    Wagner, W. E. (Editor); Velez, C. E. (Editor)

    1972-01-01

    The mathematical specifications of the Goddard trajectory determination subsystem of the flight dynamics system are presented. These specifications include the mathematical description of the coordinate systems, dynamic and measurement model, numerical integration techniques, and statistical estimation concepts.

  18. Solar electric propulsion thrust subsystem development

    NASA Technical Reports Server (NTRS)

    Masek, T. D.

    1973-01-01

    The Solar Electric Propulsion System developed under this program was designed to demonstrate all the thrust subsystem functions needed on an unmanned planetary vehicle. The demonstration included operation of the basic elements, power matching input and output voltage regulation, three-axis thrust vector control, subsystem automatic control including failure detection and correction capability (using a PDP-11 computer), operation of critical elements in thermal-vacuum-, zero-gravity-type propellant storage, and data outputs from all subsystem elements. The subsystem elements, functions, unique features, and test setup are described. General features and capabilities of the test-support data system are also presented. The test program culminated in a 1500-h computer-controlled, system-functional demonstration. This included simultaneous operation of two thruster/power conditioner sets. The results of this testing phase satisfied all the program goals.

  19. More About Beam-Steering Subsystem For Laser Communication

    NASA Technical Reports Server (NTRS)

    Page, Norman A.; Chen, Chien-Chu; Hemmati, Hamid; Lesh, James R.

    1995-01-01

    Two reports present additional information about developmental beam-steering subsystem of laser-communication system. Aspects of this subsystem described previously in "Beam-Steering Subsystem for Laser Communication" (NPO-19069) and "Digital Controller for Laser-Beam-Steering Subsystem" (NPO-19193). Reports reiterate basic principles of operation of beam-steering subsystem and of laser-communication system as whole. Also presents some of details of optical and mechanical design of prototype of subsystem, called Optical Communication Demonstrator.

  20. Periodic subsystem density-functional theory

    SciTech Connect

    Genova, Alessandro; Pavanello, Michele; Ceresoli, Davide

    2014-11-07

    By partitioning the electron density into subsystem contributions, the Frozen Density Embedding (FDE) formulation of subsystem Density Functional Theory (DFT) has recently emerged as a powerful tool for reducing the computational scaling of Kohn–Sham DFT. To date, however, FDE has been employed to molecular systems only. Periodic systems, such as metals, semiconductors, and other crystalline solids have been outside the applicability of FDE, mostly because of the lack of a periodic FDE implementation. To fill this gap, in this work we aim at extending FDE to treat subsystems of molecular and periodic character. This goal is achieved by a dual approach. On one side, the development of a theoretical framework for periodic subsystem DFT. On the other, the realization of the method into a parallel computer code. We find that periodic FDE is capable of reproducing total electron densities and (to a lesser extent) also interaction energies of molecular systems weakly interacting with metallic surfaces. In the pilot calculations considered, we find that FDE fails in those cases where there is appreciable density overlap between the subsystems. Conversely, we find FDE to be in semiquantitative agreement with Kohn–Sham DFT when the inter-subsystem density overlap is low. We also conclude that to make FDE a suitable method for describing molecular adsorption at surfaces, kinetic energy density functionals that go beyond the GGA level must be employed.

  1. Lightning testing at the subsystem level

    NASA Technical Reports Server (NTRS)

    Luteran, Frank

    1991-01-01

    Testing at the subsystem or black box level for lightning hardness is required if system hardness is to be assured at the system level. The often applied philosophy of lighting testing only at the system level leads to extensive end of the line design changes which result in excessive costs and time delays. In order to perform testing at the subsystem level two important factors must be defined to make the testing simulation meaningful. The first factor is the definition of the test stimulus appropriate to the subsystem level. Application of system level stimulations to the subsystem level usually leads to significant overdesign of the subsystem which is not necessary and may impair normal subsystem performance. The second factor is the availability of test equipment needed to provide the subsystem level lightning stimulation. Equipment for testing at this level should be portable or at least movable to enable efficient testing in a design laboratory environment. Large fixed test installations for system level tests are not readily available for use by the design engineers at the subsystem level and usually require special operating skills. The two factors, stimulation level and test equipment availability, must be evaluated together in order to produce a practical, workable test standard. The neglect or subordination of either factor will guarantee failure in generating the standard. It is not unusual to hear that test standards or specifications are waived because a specified stimulation level cannot be accomplished by in-house or independent test facilities. Determination of subsystem lightning simulation level requires a knowledge and evaluation of field coupling modes, peak and median levels of voltages and currents, bandwidths, and repetition rates. Practical limitations on test systems may require tradeoffs in lightning stimulation parameters in order to build practical test equipment. Peak power levels that can be generated at specified bandwidths with

  2. Engineering model 8-cm thruster subsystem

    NASA Technical Reports Server (NTRS)

    Herron, B. G.; Hyman, J.; Hopper, D. J.; Williamson, W. S.; Dulgeroff, C. R.; Collett, C. R.

    1978-01-01

    An Engineering Model (EM) 8 cm Ion Thruster Propulsion Subsystem was developed for operation at a thrust level 5 mN (1.1 mlb) at a specific impulse 1 sub sp = 2667 sec with a total system input power P sub in = 165 W. The system dry mass is 15 kg with a mercury-propellant-reservoir capacity of 8.75 kg permitting uninterrupted operation for about 12,500 hr. The subsystem can be started from a dormant condition in a time less than or equal to 15 min. The thruster has a design lifetime of 20,000 hr with 10,000 startup cycles. A gimbal unit is included to provide a thrust vector deflection capability of + or - 10 degrees in any direction from the zero position. The EM subsystem development program included thruster optimization, power-supply circuit optimization and flight packaging, subsystem integration, and subsystem acceptance testing including a cyclic test of the total propulsion package.

  3. Thermal analyses of power subsystem components

    NASA Technical Reports Server (NTRS)

    Morehouse, Jeffrey H.

    1990-01-01

    The hiatus in the Space Shuttle (Orbiter) program provided time for an in-depth examination of all the subsystems and their past performance. Specifically, problems with reliability and/or operating limits were and continue to be of major engineering concern. The Orbiter Auxiliary Power Unit (APU) currently operates with electric resistance line heaters which are controlled with thermostats. A design option simplification of this heater subsystem is being considered which would use self-regulating heaters. A determination of the properties and thermal operating characteristics of these self-regulating heaters was needed. The Orbiter fuel cells are cooled with a freon loop. During a loss of external heat exchanger coolant flow, the single pump circulating the freon is to be left running. It was unknown what temperature and flow rate transient conditions of the freon would provide the required fuel cell cooling and for how long. The overall objective was the development of the thermal characterization and subsequent analysis of both the proposed self-regulating APU heater and the fuel cell coolant loop subsystem. The specific objective of the APU subsystem effort was to determine the feasibility of replacing the current heater and thermostat arrangement with a self-regulating heater. The specific objective of the fuel cell coolant subsystem work was to determine the tranient coolant temperature and associated flow rates during a loss-of-external heat exchanger flow.

  4. Embedded Thermal Control for Spacecraft Subsystems Miniaturization

    NASA Technical Reports Server (NTRS)

    Didion, Jeffrey R.

    2014-01-01

    Optimization of spacecraft size, weight and power (SWaP) resources is an explicit technical priority at Goddard Space Flight Center. Embedded Thermal Control Subsystems are a promising technology with many cross cutting NSAA, DoD and commercial applications: 1.) CubeSatSmallSat spacecraft architecture, 2.) high performance computing, 3.) On-board spacecraft electronics, 4.) Power electronics and RF arrays. The Embedded Thermal Control Subsystem technology development efforts focus on component, board and enclosure level devices that will ultimately include intelligent capabilities. The presentation will discuss electric, capillary and hybrid based hardware research and development efforts at Goddard Space Flight Center. The Embedded Thermal Control Subsystem development program consists of interrelated sub-initiatives, e.g., chip component level thermal control devices, self-sensing thermal management, advanced manufactured structures. This presentation includes technical status and progress on each of these investigations. Future sub-initiatives, technical milestones and program goals will be presented.

  5. Thermoelectric Integrated Membrane Evaporation Subsystem operational improvements

    NASA Technical Reports Server (NTRS)

    Dehner, G. F.; Winkler, H. E.; Reysa, R. P.

    1984-01-01

    A three-man preprototype Thermoelectric Integrated Membrane Evaporation Subsystem (TIMES) has been developed to provide high quality water recovery from waste fluids on extended duration space flights. In the most recent effort, a number of improvements have been made to simplify subsystem operation and increase performance. These modifications include changes to the hollow fiber membrane evaporator, the condensing section of the thermoelectric heat pump, and the electronic controller logic and display. This paper describes the results of the test program that was conducted to evaluate the implemented improvements. In addition, an advanced design concept is discussed that will provide lower electrical power consumption, greater water production capacity, lower weight, and a smaller package than the present subsystem configuration.

  6. Robust Decentralized Controller Design: Subsystem Approach

    NASA Astrophysics Data System (ADS)

    Rosinová, Danica; Thuan, Nguyen Quang; Veselý, Vojtech; Marko, L'ubomír

    2012-01-01

    The paper addresses the problem of the robust output feedback PI controller design for complex large-scale stable systems with a state decentralized control structure. A decentralized control design procedure is proposed for static output feedback control which is based on solving robust control design problems of subsystems' size. The presented approach is based on the Generalized Gershgorin Theorem and uses the so-called equivalent subsystems approach to consider the interactions in the local robust controller design. The resulting decentralized control scheme has been successfully tested on two examples: a linearized model of three interconnected boiler-turbine subsystems and a linear model of four cooperating DC motors where the problem is to design four local PI controllers for a large scale system which will guarantee robust stability and performance of the closed-loop uncertain system.

  7. Mark 3 VLBI system: Tropospheric calibration subsystems

    NASA Technical Reports Server (NTRS)

    Resch, G. M.

    1980-01-01

    Tropospheric delay calibrations are implemented in the Mark 3 system with two subsystems. Estimates of the dry component of tropospheric delay are provided by accurate barometric data from a subsystem of surface meteorological sensors (SMS). An estimate of the wet component of tropospheric delay is provided by a water vapor radiometer (WVR). Both subsystems interface directly to the ASCII Transceiver bus of the Mark 3 system and are operated by the control computer. Seven WVR's under construction are designed to operate in proximity to a radio telescope and can be commanded to point along the line-of-sight to a radio source. They should provide a delay estimate that is accurate to the + or - 2 cm level.

  8. Air and water quality monitor assessment of life support subsystems

    NASA Technical Reports Server (NTRS)

    Whitley, Ken; Carrasquillo, Robyn L.; Holder, D.; Humphries, R.

    1988-01-01

    Preprotype air revitalization and water reclamation subsystems (Mole Sieve, Sabatier, Static Feed Electrolyzer, Trace Contaminant Control, and Thermoelectric Integrated Membrane Evaporative Subsystem) were operated and tested independently and in an integrated arrangement. During each test, water and/or gas samples were taken from each subsystem so that overall subsystem performance could be determined. The overall test design and objectives for both subsystem and integrated subsystem tests were limited, and no effort was made to meet water or gas specifications. The results of chemical analyses for each of the participating subsystems are presented along with other selected samples which were analyzed for physical properties and microbiologicals.

  9. MIUS integration and subsystems test program

    NASA Technical Reports Server (NTRS)

    Beckham, W. S., Jr.; Shows, G. C.; Redding, T. E.; Wadle, R. C.; Keough, M. B.; Poradek, J. C.

    1976-01-01

    The MIUS Integration and Subsystems Test (MIST) facility at the Lyndon B. Johnson Space Center was completed and ready in May 1974 for conducting specific tests in direct support of the Modular Integrated Utility System (MIUS). A series of subsystems and integrated tests was conducted since that time, culminating in a series of 24-hour dynamic tests to further demonstrate the capabilities of the MIUS Program concepts to meet typical utility load profiles for a residential area. Results of the MIST Program are presented which achieved demonstrated plant thermal efficiencies ranging from 57 to 65 percent.

  10. Electrochemical energy storage subsystems study, volume 1

    NASA Technical Reports Server (NTRS)

    Miller, F. Q.; Richardson, P. W.; Graff, C. L.; Jordan, M. V.; Patterson, V. L.

    1981-01-01

    The effects on life cycle costs (LCC) of major design and performance technology parameters for multi kW LEO and GEO energy storage subsystems using NiCd and NiH2 batteries and fuel cell/electrolysis cell devices were examined. Design, performance and LCC dynamic models are developed based on mission and system/subsystem requirements and existing or derived physical and cost data relationships. The models define baseline designs and costs. The major design and performance parameters are each varied to determine their influence on LCC around the baseline values.

  11. Small spacecraft power and thermal subsystems

    NASA Technical Reports Server (NTRS)

    Eakman, D.; Lambeck, R.; Mackowski, M.; Slifer, L., Jr.

    1994-01-01

    This white paper provides a general guide to the conceptual design of satellite power and thermal control subsystems with special emphasis on the unique design aspects associated with small satellites. The operating principles of these technologies are explained and performance characteristics of current and projected components are provided. A tutorial is presented on the design process for both power and thermal subsystems, with emphasis on unique issues relevant to small satellites. The ability of existing technology to meet future performance requirements is discussed. Conclusions and observations are presented that stress cost-effective, high-performance design solutions.

  12. Apollo experience report: Thermal protection subsystem

    NASA Technical Reports Server (NTRS)

    Pavlosky, J. E.; St.leger, L. G.

    1974-01-01

    The Apollo command module was the first manned spacecraft to be designed to enter the atmosphere of the earth at lunar-return velocity, and the design of the thermal protection subsystem for the resulting entry environment presented a major technological challenge. Brief descriptions of the Apollo command module thermal design requirements and thermal protection configuration, and some highlights of the ground and flight testing used for design verification of the system are presented. Some of the significant events that occurred and decisions that were made during the program concerning the thermal protection subsystem are discussed.

  13. Electrochemical Energy Storage Subsystems Study, Volume 2

    NASA Technical Reports Server (NTRS)

    Miller, F. Q.; Richardson, P. W.; Graff, C. L.; Jordan, M. V.; Patterson, V. L.

    1981-01-01

    The effects on life cycle costs (LCC) of major design and performance technology parameters for multi kW LEO and GEO energy storage subsystems using NiCd and NiH2 batteries and fuel cell/electrolysis cell devices were examined. Design, performance and LCC dynamic models are developed based on mission and system/subsystem requirements and existing or derived physical and cost data relationships. The models are exercised to define baseline designs and costs. Then the major design and performance parameters are each varied to determine their influence on LCC around the baseline values.

  14. JOB BUILDER remote batch processing subsystem

    NASA Technical Reports Server (NTRS)

    Orlov, I. G.; Orlova, T. L.

    1980-01-01

    The functions of the JOB BUILDER remote batch processing subsystem are described. Instructions are given for using it as a component of a display system developed by personnel of the System Programming Laboratory, Institute of Space Research, USSR Academy of Sciences.

  15. Spectroscopic Subsystems in Nearby Wide Binaries

    NASA Astrophysics Data System (ADS)

    Tokovinin, Andrei

    2015-12-01

    Radial velocity (RV) monitoring of solar-type visual binaries has been conducted at the CTIO/SMARTS 1.5 m telescope to study short-period systems. The data reduction is described, and mean and individual RVs of 163 observed objects are given. New spectroscopic binaries are discovered or suspected in 17 objects, and for some of them the orbital periods could be determined. Subsystems are efficiently detected even in a single observation by double lines and/or by the RV difference between the components of visual binaries. The potential of this detection technique is quantified by simulation and used for statistical assessment of 96 wide binaries within 67 pc. It is found that 43 binaries contain at least one subsystem, and the occurrence of subsystems is equally probable in either primary or secondary components. The frequency of subsystems and their periods matches the simple prescription proposed by the author. The remaining 53 simple wide binaries with a median projected separation of 1300 AU have an RV difference distribution between their components that is not compatible with the thermal eccentricity distribution f (e) = 2e but rather matches the uniform eccentricity distribution.

  16. Electronic Subsystems For Laser Communication System

    NASA Technical Reports Server (NTRS)

    Long, Catherine; Maruschak, John; Patschke, Robert; Powers, Michael

    1992-01-01

    Electronic subsystems of free-space laser communication system carry digital signals at 650 Mb/s over long distances. Applicable to general optical communications involving transfer of great quantities of data, and transmission and reception of video images of high definition.

  17. Integrating the autonomous subsystems management process

    NASA Technical Reports Server (NTRS)

    Ashworth, Barry R.

    1992-01-01

    Ways in which the ranking of the Space Station Module Power Management and Distribution testbed may be achieved and an individual subsystem's internal priorities may be managed within the complete system are examined. The application of these results in the integration and performance leveling of the autonomously managed system is discussed.

  18. Apollo experience report: Service propulsion subsystem

    NASA Technical Reports Server (NTRS)

    Gibson, C. R.; Wood, J. A.

    1973-01-01

    The significant service propulsion subsystem development, qualification, and flight experience from the early portion of the Apollo Program through the first lunar-landing mission is presented. Particular emphasis is given to problems encountered and solutions used to eliminate the problems.

  19. On reduced density matrices for disjoint subsystems

    NASA Astrophysics Data System (ADS)

    Iglói, F.; Peschel, I.

    2010-02-01

    We show that spin and fermion representations for solvable quantum chains lead in general to different reduced density matrices if the subsystem is not singly connected. We study the effect for two sites in XX and XY chains as well as for sublattices in XX and transverse Ising chains.

  20. The modular power subsystem for the multimission modular spacecraft

    NASA Technical Reports Server (NTRS)

    Harris, D. W.

    1978-01-01

    The block diagram, subsystems, and components of the modular power subsystem for the multimission modular spacecraft (MMS) are described. The basic design studies were guided by considerations of cost, efficiency, simplicity, and flexibility to serve a variety of missions. Components discussed are the power regulator unit, the power control unit, the signal conditioning assembly, bus protection assembly, and the 20 Ah and 50 Ah batteries. The plan for the modular power subsystem protoflight module tests is shown. The testing has four phases: (1) component level tests, (2) subsystem integration and initial performance test, (3) subsystem protoflight environmental tests, and (4) subsystem final performance tests, qualification/acceptance review and delivery.

  1. Apollo experience report: Launch escape propulsion subsystem

    NASA Technical Reports Server (NTRS)

    Townsend, N. A.

    1973-01-01

    The Apollo launch escape propulsion subsystem contained three solid rocket motors. The general design, development, and qualification of the solid-propellant pitch-control, tower-jettison, and launch-escape motors of the Apollo launch escape propulsion subsystem were completed during years 1961 to 1966. The launch escape system components are described in general terms, and the sequence of events through the ground-based test programs and flight-test programs is discussed. The initial ground rules established for this system were that it should use existing technology and designs as much as possible. The practicality of this decision is proved by the minimum number of problems that were encountered during the development and qualification program.

  2. Controls Interfaces for Two ALICE Subsystems

    NASA Astrophysics Data System (ADS)

    Thomen, Robert

    2007-10-01

    Software for the control of a laser alignment system for the Inner Tacking System (ITS) and for the Electromagnetic Calorimeter (EMC) was developed for the ALICE (A Large Ion Collider Experiment) at CERN. The interfaces for both subsystems use the CERN-standard hardware controls system PVSS (Prozessvisualisierungs- und Steuerungs-System). Software for the ITS has been created to measure the relative alignment of the ITS with the Time Projection Chamber (TPC) so to ensure accurate particle tracking. The ITS alignment system locates laser images in four cameras. The EMC requires several subsystems to be running in order to operate properly. Software has been created and tested for the detector's high and low voltage systems, and temperature monitoring hardware. The ITS and EMC software specifications and design requirements are presented and their performance is analyzed.

  3. Shuttle Orbiter Atmospheric Revitalization Pressure Control Subsystem

    NASA Technical Reports Server (NTRS)

    Walleshauser, J. J.; Ord, G. R.; Prince, R. N.

    1982-01-01

    The Atmospheric Revitalization Pressure Control Subsystem (ARPCS) provides oxygen partial pressure and total pressure control for the habitable atmosphere of the Shuttle for either a one atmosphere environment or an emergency 8 PSIA mode. It consists of a Supply Panel, Control Panel, Cabin Pressure Relief Valves and Electronic Controllers. The panels control and monitor the oxygen and nitrogen supplies. The cabin pressure relief valves protect the habitable environment from overpressurization. Electronic controllers provide proper mixing of the two gases. This paper describes the ARPCS, addresses the changes in hardware that have occurred since the inception of the program; the performance of this subsystem during STS-1 and STS-2; and discusses future operation modes.

  4. Fiber Bragg gratings for microwave photonics subsystems.

    PubMed

    Wang, Chao; Yao, Jianping

    2013-09-23

    Microwave photonics (MWP) is an emerging filed in which photonic technologies are employed to enable and enhance functionalities in microwave systems which are usually very challenging to fulfill directly in the microwave domain. Various photonic devices have been used to achieve the functions. A fiber Bragg grating (FBG) is one of the key components in microwave photonics systems due to its unique features such as flexible spectral characteristics, low loss, light weight, compact footprint, and inherent compatibility with other fiber-optic devices. In this paper, we discuss the recent development in employing FBGs for various microwave photonics subsystems, with an emphasis on subsystems for microwave photonic signal processing and microwave arbitrary waveform generation. The limitations and potential solutions are also discussed. PMID:24104174

  5. Analysis of the human operator subsystems

    NASA Technical Reports Server (NTRS)

    Jones, Lynette A.; Hunter, Ian W.

    1991-01-01

    Except in low-bandwidth systems, knowledge of the human operator transfer function is essential for high-performance telerobotic systems. This information has usually been derived from detailed analyses of tracking performance, in which the human operator is considered as a complete system rather than as a summation of a number of subsystems, each of which influences the operator's output. Studies of one of these subsystems, the limb mechanics system, demonstrate that large parameter variations can occur that can have a profound effect on the stability of force-reflecting telerobot systems. An objective of this research was to decompose the performance of the human operator system in order to establish how the dynamics of each of the elements influence the operator's responses.

  6. Apollo experience report: Electrical wiring subsystem

    NASA Technical Reports Server (NTRS)

    White, L. D.

    1975-01-01

    The general requirements of the electrical wiring subsystems and the problem areas and solutions that occurred during the major part of the Apollo Program are detailed in this report. The concepts and definitions of specific requirements for electrical wiring; wire-connecting devices; and wire-harness fabrication, checkout, and installation techniques are discussed. The design and development of electrical wiring and wire-connecting devices are described. Mission performance is discussed, and conclusions and recommendations for future programs are presented.

  7. Power and pyro subsystems for Mars Pathfinder

    SciTech Connect

    Shirbacheh, M.

    1997-12-31

    The Power and Pyro Subsystem (PPS) for Mars Pathfinder was designed to support the spacecraft activities during Launch, Cruise, Entry and Landing and Mars operation phases of the mission. The key design constraints were cost, volume and mass. The PPS consists of solar arrays, batteries and power electronics. This paper describes the Mars Pathfinder mission, key requirements on PPS, and PPS system architecture and description of each element of the PPS system.

  8. Portable Oxygen Subsystem (POS). [for space shuttles

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Concept selection, design, fabrication, and testing of a Portable Subsystem (POS) for use in space shuttle operations are described. Tradeoff analyses were conducted to determine the POS concept for fabrication and testing. The fabricated POS was subjected to unmanned and manned tests to verify compliance with statement of work requirements. The POS used in the development program described herein met requirements for the three operational modes -- prebreathing, contaminated cabin, and personnel rescue system operations.

  9. Automated searching for quantum subsystem codes

    SciTech Connect

    Crosswhite, Gregory M.; Bacon, Dave

    2011-02-15

    Quantum error correction allows for faulty quantum systems to behave in an effectively error-free manner. One important class of techniques for quantum error correction is the class of quantum subsystem codes, which are relevant both to active quantum error-correcting schemes as well as to the design of self-correcting quantum memories. Previous approaches for investigating these codes have focused on applying theoretical analysis to look for interesting codes and to investigate their properties. In this paper we present an alternative approach that uses computational analysis to accomplish the same goals. Specifically, we present an algorithm that computes the optimal quantum subsystem code that can be implemented given an arbitrary set of measurement operators that are tensor products of Pauli operators. We then demonstrate the utility of this algorithm by performing a systematic investigation of the quantum subsystem codes that exist in the setting where the interactions are limited to two-body interactions between neighbors on lattices derived from the convex uniform tilings of the plane.

  10. Mariner Mars 1971 attitude control subsystem

    NASA Technical Reports Server (NTRS)

    Edmunds, R. S.

    1974-01-01

    The Mariner Mars 1971 attitude control subsystem (ACS) is discussed. It is comprised of a sun sensor set, a Canopus tracker, an inertial reference unit, two cold gas reaction control assemblies, two rocket engine gimbal actuators, and an attitude control electronics unit. The subsystem has the following eight operating modes: (1) launch, (2) sun acquisition, (3) roll search, (4) celestial cruise, (5) all-axes inertial, (6) roll inertial, (7) commanded turn, and (8) thrust vector control. In the celestial cruise mode, the position control is held to plus or minus 0.25 deg. Commanded turn rates are plus or minus 0.18 deg/s. The attitude control logic in conjunction with command inputs from other spacecraft subsystems establishes the ACS operating mode. The logic utilizes Sun and Canopus acquisition signals generated within the ACS to perform automatic mode switching so that dependence of ground control is minimized when operating in the sun acquisition, roll search, and celestial cruise modes. The total ACS weight is 65.7 lb, and includes 5.4 lb of nitrogen gas. Total power requirements vary from 9 W for the celestial cruise mode to 54 W for the commanded turn mode.

  11. Systems integration of marketable subsystems: A collection of progress reports

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Monthly progress reports are given in the areas of marketable subsystems integration; development, design, and building of site data acquisition subsystems and data processing systems; operation of the solar test facility and a systems analysis.

  12. Stepping-Motion Motor-Control Subsystem For Testing Bearings

    NASA Technical Reports Server (NTRS)

    Powers, Charles E.

    1992-01-01

    Control subsystem closed-loop angular-position-control system causing motor and bearing under test to undergo any of variety of continuous or stepping motions. Also used to test bearing-and-motor assemblies, motors, angular-position sensors including rotating shafts, and like. Monitoring subsystem gathers data used to evaluate performance of bearing or other article under test. Monitoring subsystem described in article, "Monitoring Subsystem For Testing Bearings" (GSC-13432).

  13. Balancing reliability and cost to choose the best power subsystem

    NASA Technical Reports Server (NTRS)

    Suich, Ronald C.; Patterson, Richard L.

    1991-01-01

    A mathematical model is presented for computing total (spacecraft) subsystem cost including both the basic subsystem cost and the expected cost due to the failure of the subsystem. This model is then used to determine power subsystem cost as a function of reliability and redundancy. Minimum cost and maximum reliability and/or redundancy are not generally equivalent. Two example cases are presented. One is a small satellite, and the other is an interplanetary spacecraft.

  14. Advanced vehicle systems assessment. Volume 2: Subsystems assessment

    NASA Technical Reports Server (NTRS)

    Hardy, K.

    1985-01-01

    Volume 2 (Subsystems Assessment) is part of a five-volume report entitled Advanced Vehicle Systems Assessment. Volume 2 presents the projected performance capabilities and cost characteristics of applicable subsystems, considering an additional decade of development. Subsystems of interest include energy storage and conversion devices as well as the necessary powertrain components and vehicle subsystems. Volume 2 also includes updated battery information based on the assessment of an independent battery review board (with the aid of subcontractor reports on advanced battery characteristics).

  15. Automated biowaste sampling system urine subsystem operating model, part 1

    NASA Technical Reports Server (NTRS)

    Fogal, G. L.; Mangialardi, J. K.; Rosen, F.

    1973-01-01

    The urine subsystem automatically provides for the collection, volume sensing, and sampling of urine from six subjects during space flight. Verification of the subsystem design was a primary objective of the current effort which was accomplished thru the detail design, fabrication, and verification testing of an operating model of the subsystem.

  16. Digital Controller For Laser-Beam-Steering Subsystem: Part 2

    NASA Technical Reports Server (NTRS)

    Ansari, Homayoon; Voisinet, Leeann

    1995-01-01

    A report presents additional information about laser-beam-steering apparatus described in "Digital Controller for Laser-Beam-Steering Subsystem" (NPO-19193) and "More About Beam-Steering Subsystem for Laser Communication" (NPO-19381). Reiterates basic principles of operation of beam-steering subsystem, with emphasis on modes of operation, basic design concepts, and initial experiments on partial prototype of apparatus.

  17. Space reactor system and subsystem investigations: Assessment of technology issues for the reactor and shield subsystem, SP-100 Program

    NASA Astrophysics Data System (ADS)

    Atkins, D. F.; Lillie, A. F.

    1983-06-01

    Preliminary assessment was completed of nuclear technology as it relates to candidate reactor/shield subsystems for the SP-100 Program. The scope of the assessment was confined to the nuclear package (to the reactor and shield subsystems). Nine generic reactor subsystems were addressed for the assessment.

  18. Space-reactor electric systems: subsystem technology assessment

    SciTech Connect

    Anderson, R.V.; Bost, D.; Determan, W.R.

    1983-03-29

    This report documents the subsystem technology assessment. For the purpose of this report, five subsystems were defined for a space reactor electric system, and the report is organized around these subsystems: reactor; shielding; primary heat transport; power conversion and processing; and heat rejection. The purpose of the assessment was to determine the current technology status and the technology potentials for different types of the five subsystems. The cost and schedule needed to develop these potentials were estimated, and sets of development-compatible subsystems were identified.

  19. The Mariner Mars 1971 radio frequency subsystem

    NASA Technical Reports Server (NTRS)

    Hughes, R. S.

    1972-01-01

    The radio frequency subsystem (RFS) for the Mariner Mars 1971 (MM'71) spacecraft is described. The MM'69 RFS was used as the baseline design for the MM'71 RFS, and the report describes the design changes made to the 1969 RFS for use on MM'71. It also cites various problems encountered during the fabrication and testing of the RFS, as well as the types of tests to which the RFS was subjected. In areas where significant problems were encountered, a detailed description of the problem and its solution is presented. In addition, some recommendations are given for modifications to the RFS and test techniques for future programs.

  20. Waves in space plasma dipole antenna subsystem

    NASA Technical Reports Server (NTRS)

    Thomson, Mark

    1993-01-01

    The Waves In Space Plasma (WISP) flight experiment requires a 50-meter-long deployable dipole antenna subsystem (DASS) to radiate radio frequencies from the STS Orbiter cargo bay. The transmissions are to excite outer ionospheric plasma between the dipole and a free-flying receiver (Spartan) for scientific purposes. This report describes the singular DASS design requirements and how the resulting design satisfies them. A jettison latch is described in some detail. The latch releases the antenna in case of any problems which might prevent the bay doors from closing for re-entry and landing of the Orbiter.

  1. Vacuum control subsystem for the Fermilab Tevatron

    SciTech Connect

    Zagel, J.R.; Chapman, L.J.

    1981-06-01

    The CAMAC 170 module and CIA crate provide a convenient, cost effective method of interfacing any system requiring a large number of simple devices to be multiplexed into the Accelerator Control System. The system is ideal for relatively slowly changing systems where ten bit analog to digital conversions are sufficiently accurate. Together with vacuum interface CIA cards and prom-based software resident in the 170, this system is used to provide intelligent local monitoring and control for the Tevatron vacuum subsystems. Although not implemented in the vacuum interface, digital to analog converters could be included on the plug in modules as well, providing a total digital and analog multiplexing scheme. 2 refs.

  2. X-38 Bolt Retractor Subsystem Separation Demonstration

    NASA Astrophysics Data System (ADS)

    Rugless, Fedoria; Johnston, A. S.; Ahmed, R.; Garrison, J. C.; Gaines, J. L.; Waggoner, J. D.

    2002-09-01

    The Flight Robotics Laboratory FRL successfully demonstrated the X-38 bolt retractor subsystem (BRS). The BRS design was proven safe by testing in the Pyrotechnic Shock Facility (PSI) before being demonstrated in the FRL. This Technical Memorandum describes the BRS, FRL, PSF, and interface hardware. Bolt retraction time, spacecraft simulator acceleration, and a force analysis are also presented. The purpose of the demonstration was to show the FRL capability for spacecraft separation testing using pyrotechnics. Although a formal test was not performed due to schedule and budget constraints, the data will show that the BRS is a successful design concept and the FRL is suitable for future separation tests.

  3. Performances of MINISAT-01 Platform Subsystems

    NASA Astrophysics Data System (ADS)

    Cerezo MartÍnez, Fernando

    2001-03-01

    This paper describes the results of the MINISAT-01 mission after two year in orbit since the launch on April 21^st of 1997. It also describes the MINISAT-01 behavior during these years and describes, the evolution of the Satellite, by subsystems. Graphics of the most important parameters will be shown to display the difference between the beginning of life and two years after. The paper details the most important events during the Satellite's life such as the battery overcharge, temperature evolution, onboard computer reset, software updating, and communication failures.

  4. Equilibration of quantum systems and subsystems

    NASA Astrophysics Data System (ADS)

    Short, Anthony J.

    2011-05-01

    We unify two recent results concerning equilibration in quantum theory. We first generalize a proof of Reimann (2008 Phys. Rev. Lett. 101 190403), that the expectation value of 'realistic' quantum observables will equilibrate under very general conditions, and discuss its implications for the equilibration of quantum systems. We then use this to re-derive an independent result of Linden et al (2009 Phys. Rev. E 79 061103), showing that small subsystems generically evolve to an approximately static equilibrium state. Finally, we consider subspaces in which all initial states effectively equilibrate to the same state.

  5. SEP thrust subsystem performance sensitivity analysis

    NASA Technical Reports Server (NTRS)

    Atkins, K. L.; Sauer, C. G., Jr.; Kerrisk, D. J.

    1973-01-01

    This is a two-part report on solar electric propulsion (SEP) performance sensitivity analysis. The first part describes the preliminary analysis of the SEP thrust system performance for an Encke rendezvous mission. A detailed description of thrust subsystem hardware tolerances on mission performance is included together with nominal spacecraft parameters based on these tolerances. The second part describes the method of analysis and graphical techniques used in generating the data for Part 1. Included is a description of both the trajectory program used and the additional software developed for this analysis. Part 2 also includes a comprehensive description of the use of the graphical techniques employed in this performance analysis.

  6. LARES Mission: Separation and Retention Subsystem

    NASA Technical Reports Server (NTRS)

    Bursi, Alessandro; Camilli, Pierluigi; Piredda, Claudio; Babini, Gianni; Mangraviti, Elio

    2014-01-01

    As part of the Lares (LAser RElativity Satellite) mission, an all-Italian scientific mission launched with the Vega maiden flight in February 2012, a mechanical separation and retention subsystem (SSEP) has been developed to retain the LARES satellite during launch and release it in the final orbit. The design flow was based on the identification of the driving requirements and critical areas to guide the trade-off, design, analysis and test activities. In particular, the SSEP had to face very high environmental loads and to minimize the contact areas with the satellite that had a spherical shape. The test activity overview is provided.

  7. High temperature superconducting digital circuits and subsystems

    SciTech Connect

    Martens, J.S.; Pance, A.; Whiteley, S.R.; Char, K.; Johansson, M.F.; Lee, L.; Hietala, V.M.; Wendt, J.R.; Hou, S.Y.; Phillips, J.

    1993-10-01

    The advances in the fabrication of high temperature superconducting devices have enabled the demonstration of high performance and useful digital circuits and subsystems. The yield and uniformity of the devices is sufficient for circuit fabrication at the medium scale integration (MSI) level with performance not seen before at 77 K. The circuits demonstrated to date include simple gates, counters, analog to digital converters, and shift registers. All of these are mid-sized building blocks for potential applications in commercial and military systems. The processes used for these circuits and blocks will be discussed along with observed performance data.

  8. Preprototype Vapor Compression Distillation Subsystem development

    NASA Technical Reports Server (NTRS)

    Thompson, C. D.; Ellis, G. S.; Schubert, F. H.

    1981-01-01

    Vapor Compression Distillation (VCD) has evolved as the most promising approach to reclaim potable water from wastewater for future long-term manned space missions. Life Systems, Inc. (LSI), working with NASA, has developed a preprototype Vapor Compression Distillation Subsystem (VCDS) which processes wastewater at 1.4 kg/h. The preprototype unit weighs 143 kg, occupies a volume of 0.47 cu m, and will reclaim 96 percent of the available wastewater. This unit has been tested by LSI and is scheduled for further testing at NASA-JSC. This paper presents the preprototype VCDS design, configuration, performance data, test results and flight system projections.

  9. Development of shutter subsystems for infrared imagers

    NASA Astrophysics Data System (ADS)

    Dewitt, Frank; Durfee, David; Stephenson, Stanley; Wagner, Gary

    2010-04-01

    Requirements for shutters used in Infrared Thermal Weapon Sight (TWS) systems, Driver Vision Enhancement (DVE) and other thermal imaging systems are becoming increasingly more demanding. These performance requirements have been achieved using a unique, modular, reconfigurable rotary drive actuator with bi-stability and direct connection to the blade. A "Smart Shutter" acts as a complete sub-system that can be tested as an integral module. A multi-blade variant has been developed that retains the reliability of the rotary drive system and decreases the physical size of largeraperture shutters. Predictions of next-generation application-specific shutter designs will be offered in the paper.

  10. Loading operations for spacecraft propulsion subsystems

    NASA Astrophysics Data System (ADS)

    Purohit, G. P.; Nordeng, H. O.; Ellison, J. R.

    1992-07-01

    This paper provides a broad overview of loading operations for pressurized blowdown monopropellant and pressure regulated integral bipropellant propulsion subsystems used in geosynchronous communication satellites. Propellant chemical composition, cleanliness, processing, and handling requirements are addressed. Ground servicing equipment (GSE) and propellant transfer procedures for the various loading configurations are discussed. Effects of helium solubility and helium saturation levels in both GSE carts and propellant tanks are examined. Predicted equilibrium pressures for actual postload tank pressures are compared against extensive loading data on Hughes bipropellant spacecraft. Helium tank pressurization and manifold pressurization practices are described. Propellant loading facility requirements and safety requirements are discussed.

  11. Building the IOOS data management subsystem

    USGS Publications Warehouse

    de La Beaujardière, J.; Mendelssohn, R.; Ortiz, C.; Signell, R.

    2010-01-01

    We discuss progress to date and plans for the Integrated Ocean Observing System (IOOS??) Data Management and Communications (DMAC) subsystem. We begin by presenting a conceptual architecture of IOOS DMAC. We describe work done as part of a 3-year pilot project known as the Data Integration Framework and the subsequent assessment of lessons learned. We present work that has been accomplished as part of the initial version of the IOOS Data Catalog. Finally, we discuss near-term plans for augmenting IOOS DMAC capabilities.

  12. Operation of the yield estimation subsystem

    NASA Technical Reports Server (NTRS)

    Mccrary, D. G.; Rogers, J. L.; Hill, J. D. (Principal Investigator)

    1979-01-01

    The organization and products of the yield estimation subsystem (YES) are described with particular emphasis on meteorological data acquisition, yield estimation, crop calendars, weekly weather summaries, and project reports. During the three phases of LACIE, YES demonstrated that it is possible to use the flow of global meteorological data and provide valuable information regarding global wheat production. It was able to establish a capability to collect, in a timely manner, detailed weather data from all regions of the world, and to evaluate and convert that data into information appropriate to the project's needs.

  13. STC-DBS Electrical Power Subsystem

    SciTech Connect

    Peck, S.R.; Callen, P.; Pierce, P.; Wylie, T.

    1984-08-01

    The design of the STC-DBS (Satellite Television Corporation - Direct Broadcast Satellite) Electrical Power Subsystem presently under development at RCA Astro-Electronics is highlighted. To efficiently satisfy the payload power requirements, which are dominated by three 220W TWTAs, while at the same time permitting maximum use of already qualified designs, a dual bus system was selected. The payload bus, which operates during non-eclipse periods, is a shunt-regulated solar array bus at 100 volts. The housekeeping bus is regulated at 35.5 volts when sunlit and varies with the battery voltage during eclipse.

  14. X-38 Bolt Retractor Subsystem Separation Demonstration

    NASA Technical Reports Server (NTRS)

    Rugless, Fedoria (Editor); Johnston, A. S.; Ahmed, R.; Garrison, J. C.; Gaines, J. L.; Waggoner, J. D.

    2002-01-01

    The Flight Robotics Laboratory FRL successfully demonstrated the X-38 bolt retractor subsystem (BRS). The BRS design was proven safe by testing in the Pyrotechnic Shock Facility (PSI) before being demonstrated in the FRL. This Technical Memorandum describes the BRS, FRL, PSF, and interface hardware. Bolt retraction time, spacecraft simulator acceleration, and a force analysis are also presented. The purpose of the demonstration was to show the FRL capability for spacecraft separation testing using pyrotechnics. Although a formal test was not performed due to schedule and budget constraints, the data will show that the BRS is a successful design concept and the FRL is suitable for future separation tests.

  15. Fault-tolerant multichannel demultiplexer subsystems

    NASA Technical Reports Server (NTRS)

    Redinbo, Robert

    1991-01-01

    Fault tolerance in future processing and switching communication satellites is addressed by showing new methods for detecting hardware failures in the first major subsystem, the multichannel demultiplexer. An efficient method for demultiplexing frequency slotted channels uses multirate filter banks which contain fast Fourier transform processing. All numerical processing is performed at a lower rate commensurate with the small bandwidth of each bandbase channel. The integrity of the demultiplexing operations is protected by using real number convolutional codes to compute comparable parity values which detect errors at the data sample level. High rate, systematic convolutional codes produce parity values at a much reduced rate, and protection is achieved by generating parity values in two ways and comparing them. Parity values corresponding to each output channel are generated in parallel by a subsystem, operating even slower and in parallel with the demultiplexer that is virtually identical to the original structure. These parity calculations may be time shared with the same processing resources because they are so similar.

  16. Automating engineering verification in ALMA subsystems

    NASA Astrophysics Data System (ADS)

    Ortiz, José; Castillo, Jorge

    2014-08-01

    The Atacama Large Millimeter/submillimeter Array is an interferometer comprising 66 individual high precision antennas located over 5000 meters altitude in the north of Chile. Several complex electronic subsystems need to be meticulously tested at different stages of an antenna commissioning, both independently and when integrated together. First subsystem integration takes place at the Operations Support Facilities (OSF), at an altitude of 3000 meters. Second integration occurs at the high altitude Array Operations Site (AOS), where also combined performance with Central Local Oscillator (CLO) and Correlator is assessed. In addition, there are several other events requiring complete or partial verification of instrument specifications compliance, such as parts replacements, calibration, relocation within AOS, preventive maintenance and troubleshooting due to poor performance in scientific observations. Restricted engineering time allocation and the constant pressure of minimizing downtime in a 24/7 astronomical observatory, impose the need to complete (and report) the aforementioned verifications in the least possible time. Array-wide disturbances, such as global power interruptions and following recovery, generate the added challenge of executing this checkout on multiple antenna elements at once. This paper presents the outcome of the automation of engineering verification setup, execution, notification and reporting in ALMA and how these efforts have resulted in a dramatic reduction of both time and operator training required. Signal Path Connectivity (SPC) checkout is introduced as a notable case of such automation.

  17. Electrochemical carbon dioxide concentrator subsystem development

    NASA Technical Reports Server (NTRS)

    Koszenski, E. P.; Heppner, D. B.; Bunnell, C. T.

    1986-01-01

    The most promising concept for a regenerative CO2 removal system for long duration manned space flight is the Electrochemical CO2 Concentrator (EDC), which allows for the continuous, efficient removal of CO2 from the spacecraft cabin. This study addresses the advancement of the EDC system by generating subsystem and ancillary component reliability data through extensive endurance testing and developing related hardware components such as electrochemical module lightweight end plates, electrochemical module improved isolation valves, an improved air/liquid heat exchanger and a triple redundant relative humidity sensor. Efforts included fabrication and testing the EDC with a Sabatier CO2 Reduction Reactor and generation of data necessary for integration of the EDC into a space station air revitalization system. The results verified the high level of performance, reliability and durability of the EDC subsystem and ancillary hardware, verified the high efficiency of the Sabatier CO2 Reduction Reactor, and increased the overall EDC technology engineering data base. The study concluded that the EDC system is approaching the hardware maturity levels required for space station deployment.

  18. UGV: security analysis of subsystem control network

    NASA Astrophysics Data System (ADS)

    Abbott-McCune, Sam; Kobezak, Philip; Tront, Joseph; Marchany, Randy; Wicks, Al

    2013-05-01

    Unmanned Ground vehicles (UGVs) are becoming prolific in the heterogeneous superset of robotic platforms. The sensors which provide odometry, localization, perception, and vehicle diagnostics are fused to give the robotic platform a sense of the environment it is traversing. The automotive industry CAN bus has dominated the industry due to the fault tolerance and the message structure allowing high priority messages to reach the desired node in a real time environment. UGVs are being researched and produced at an accelerated rate to preform arduous, repetitive, and dangerous missions that are associated with a military action in a protracted conflict. The technology and applications of the research will inevitably be turned into dual-use platforms to aid civil agencies in the performance of their various operations. Our motivation is security of the holistic system; however as subsystems are outsourced in the design, the overall security of the system may be diminished. We will focus on the CAN bus topology and the vulnerabilities introduced in UGVs and recognizable security vulnerabilities that are inherent in the communications architecture. We will show how data can be extracted from an add-on CAN bus that can be customized to monitor subsystems. The information can be altered or spoofed to force the vehicle to exhibit unwanted actions or render the UGV unusable for the designed mission. The military relies heavily on technology to maintain information dominance, and the security of the information introduced onto the network by UGVs must be safeguarded from vulnerabilities that can be exploited.

  19. PCM Passive Cooling System Containing Active Subsystems

    NASA Technical Reports Server (NTRS)

    Blanding, David E.; Bass, David I.

    2005-01-01

    A multistage system has been proposed for cooling a circulating fluid that is subject to intermittent intense heating. The system would be both flexible and redundant in that it could operate in a basic passive mode, either sequentially or simultaneously with operation of a first, active cooling subsystem, and either sequentially or simultaneously with a second cooling subsystem that could be active, passive, or a combination of both. This flexibility and redundancy, in combination with the passive nature of at least one of the modes of operation, would make the system more reliable, relative to a conventional cooling system. The system would include a tube-in-shell heat exchanger, within which the space between the tubes would be filled with a phase-change material (PCM). The circulating hot fluid would flow along the tubes in the heat exchanger. In the basic passive mode of operation, heat would be conducted from the hot fluid into the PCM, wherein the heat would be stored temporarily by virtue of the phase change.

  20. Force protection demining system (FPDS) detection subsystem

    NASA Astrophysics Data System (ADS)

    Zachery, Karen N.; Schultz, Gregory M.; Collins, Leslie M.

    2005-06-01

    This study describes the U.S. Army Force Protection Demining System (FPDS); a remotely-operated, multisensor platform developed for reliable detection and neutralization of both anti-tank and anti-personnel landmines. The ongoing development of the prototype multisensor detection subsystem is presented, which integrates an advanced electromagnetic pulsed-induction array and ground penetrating synthetic aperture radar array on a single standoff platform. The FPDS detection subsystem is mounted on a robotic rubber-tracked vehicle and incorporates an accurate and precise navigation/positioning module making it well suited for operation in varied and irregular terrains. Detection sensors are optimally configured to minimize interference without loss in sensitivity or performance. Mine lane test data acquired from the prototype sensors are processed to extract signal- and image-based features for automatic target recognition. Preliminary results using optimal feature and classifier selection indicate the potential of the system to achieve high probabilities of detection while minimizing false alarms. The FPDS detection software system also exploits modern multi-sensor data fusion algorithms to provide real-time detection and discrimination information to the user.

  1. Instrument Pointing Subsystem /IPS/ design and performance

    NASA Astrophysics Data System (ADS)

    Hammesfahr, A. E.

    1981-01-01

    The Instrument Pointing Subsystem (IPS), currently under development at Dornier System, is a most versatile Spacelab subsystem providing precision pointing capabilities to any single or clustered group of scientific instruments observing inertially fixed or moving targets. The IPS comprises a three-axis gimbal system mounted to the payload aft end and a payload clamping assembly for support of the IPS mounted experiments during Orbiter launch and landing phases. The IPS control system is based on the inertial reference of a three-axis gyro package being updated by the payload mounted IPS star/sun trackers and operated in a gimbal mounted minicomputer. It enables inertial stabilization as well as slewing and target tracking operations. The functional and operational control is performed via the Spacelab S/S computer and its display and keyboard, thereby establishing a flexible and responsive operator interface in the Spacelab Module and the Orbiter AFD enabling optimized display and keyboard entries for any operational mode. The AFD accommodates in addition a hardwired panel serving for IPS emergency operations. Incorporated Experiment supporting services consist of several independent power sources, three Experiment Computer Remote Acquisition Units and direct data links to IPS and Spacelab which provide maximum flexibility for operation of independent experiment clusters and for an operational interlock between IPS and its payload.

  2. Thermo-mechanical analysis of polyamide biocomposites

    NASA Astrophysics Data System (ADS)

    Lattimer, Jessica Lynne

    Biobased fillers in thermoplastics have seen increased usage over the last several years. The increased usage of biobased fillers follows the ever-increasing thrust to reduce petroleum and synthetic petrochemical product consumption. Biocomposites made from polyolefin matrices have shown improved elastic moduli with moderate impact on strength. For engineering thermoplastics, the increased processing temperatures lead to degradation of the biomass, often detrimental for the mechanical performance. The goal of this work was to evaluate the effectiveness of agricultural byproducts as fillers in polyamides, while minimizing the effects of increased processing temperatures. Torrefaction has been identified as an effective means of preparing biomass for introduction into polyamide. Polyamide biocomposites were produced and shown to have comparable mechanical properties to the neat matrix. Torrefied biomass was shown to produce tensile strengths within 70% of the neat matrix, increase elastic modulus by 150%, flexural strength by 170%, and flexural modulus by 154%.

  3. IOOS modeling subsystem: vision and implementation strategy

    USGS Publications Warehouse

    Rosenfeld, Leslie; Chao, Yi; Signell, Richard P.

    2012-01-01

    Numerical modeling is vital to achieving the U.S. IOOS® goals of predicting, understanding and adapting to change in the ocean and Great Lakes. In the next decade IOOS should cultivate a holistic approach to coastal ocean prediction, and encourage more balanced investment among the observing, modeling and information management subsystems. We believe the vision of a prediction framework driven by observations, and leveraging advanced technology and understanding of the ocean and Great Lakes, would lead to a new era for IOOS that would not only produce more powerful information, but would also capture broad community support, particularly from the general public, thus allowing IOOS to develop into the comprehensive information system that was envisioned at the outset.

  4. Tracking subsystem of the SOFIA telescope

    NASA Astrophysics Data System (ADS)

    Bittner, Hermann; Braeuninger, Christoph; Dierks, Andreas; Erdmann, Matthias; Erhard, Markus; Lattner, Klaus; Schmolke, Juergen

    2000-06-01

    The Tracking Subsystem of the SOFIA telescope consists of three high performance imagers and a dedicated tracking control unit. There are two boresighted imagers for target acquisition and tracking, one with a wide (6 degrees) and one with a fine (70 arcmin) field-of-view, and one main- telescope-optics sharing imager with a narrow field-of-view (8 arcmin) for high performance tracking. From the recorded stellar images, tracking error signals are generated by the tracker controller. The tracker controller has several features to support various tracking schemes such as tracking the telescope as an inertial platform, on- axis/offset tracking, and limb tracking. The tracker has three modes, i.e. positioning, tracking and `override'. Special features are the handling of so-called areas-of- interest in the inertial reference frame and the external imager synchronization. The paper presents the design and functional/operational performance of the imagers and the tracking control unit.

  5. NASA metrology information system: A NEMS subsystem

    NASA Technical Reports Server (NTRS)

    German, E. S., Jr.; Kern, F. A.; Yow, R. P.; Peterson, E.

    1984-01-01

    the NASA Metrology Information Systems (NMIS) is being developed as a standardized tool in managing the NASA field Center's instrument calibration programs. This system, as defined by the NASA Metrology and Calibration Workshop, will function as a subsystem of the newly developed NASA Equipment Management System (NEMS). The Metrology Information System is designed to utilize and update applicable NEMS data fields for controlled property and to function as a stand alone system for noncontrolled property. The NMIS provides automatic instrument calibration recall control, instrument historical performance data storage and analysis, calibration and repair labor and parts cost data, and instrument user and location data. Nineteen standardized reports were developed to analyze calibration system operations.

  6. Development of an alkaline fuel cell subsystem

    NASA Technical Reports Server (NTRS)

    1987-01-01

    A two task program was initiated to develop advanced fuel cell components which could be assembled into an alkaline power section for the Space Station Prototype (SSP) fuel cell subsystem. The first task was to establish a preliminary SSP power section design to be representative of the 200 cell Space Station power section. The second task was to conduct tooling and fabrication trials and fabrication of selected cell stack components. A lightweight, reliable cell stack design suitable for the SSP regenerative fuel cell power plant was completed. The design meets NASA's preliminary requirements for future multikilowatt Space Station missions. Cell stack component fabrication and tooling trials demonstrated cell components of the SSP stack design of the 1.0 sq ft area can be manufactured using techniques and methods previously evaluated and developed.

  7. Verifying Correct Functionality of Avionics Subsystems

    NASA Technical Reports Server (NTRS)

    Meuer, Ben t.

    2005-01-01

    This project focuses on the testing of the telecommunications interface subsystem of the Multi-Mission System Architecture Platform to ensure proper functionality. The Multi-Mission System Architecture Platform is a set of basic tools designed to be used in future spacecraft. The responsibilities of the telecommunications interface include communication between the spacecraft and ground teams as well as acting as the bus controller for the system. The tests completed include bit wise read\\write tests to each register, testing of status bits, and verifying various bus controller activities. Testing is accomplished through the use of software-based simulations run on an electronic design of the system. The tests are written in Verilog Hardware Definition Language and they simulate specific states and conditions in telecommunication interfaces. Upon successful completion, the output is examined to verify that the system responded appropriately.

  8. Apollo experience report: Lunar module electrical power subsystem

    NASA Technical Reports Server (NTRS)

    Campos, A. B.

    1972-01-01

    The design and development of the electrical power subsystem for the lunar module are discussed. The initial requirements, the concepts used to design the subsystem, and the testing program are explained. Specific problems and the modifications or compromises (or both) imposed for resolution are detailed. The flight performance of the subsystem is described, and recommendations pertaining to power specifications for future space applications are made.

  9. A Statistical Approach to Establishing Subsystem Environmental Test Specifications

    NASA Technical Reports Server (NTRS)

    Keegan, W. B.

    1974-01-01

    Results are presented of a research task to evaluate structural responses at various subsystem mounting locations during spacecraft level test exposures to the environments of mechanical shock, acoustic noise, and random vibration. This statistical evaluation is presented in the form of recommended subsystem test specifications for these three environments as normalized to a reference set of spacecraft test levels and are thus suitable for extrapolation to a set of different spacecraft test levels. The recommendations are dependent upon a subsystem's mounting location in a spacecraft, and information is presented on how to determine this mounting zone for a given subsystem.

  10. Plant development, auxin, and the subsystem incompleteness theorem.

    PubMed

    Niklas, Karl J; Kutschera, Ulrich

    2012-01-01

    Plant morphogenesis (the process whereby form develops) requires signal cross-talking among all levels of organization to coordinate the operation of metabolic and genomic subsystems operating in a larger network of subsystems. Each subsystem can be rendered as a logic circuit supervising the operation of one or more signal-activated system. This approach simplifies complex morphogenetic phenomena and allows for their aggregation into diagrams of progressively larger networks. This technique is illustrated here by rendering two logic circuits and signal-activated subsystems, one for auxin (IAA) polar/lateral intercellular transport and another for IAA-mediated cell wall loosening. For each of these phenomena, a circuit/subsystem diagram highlights missing components (either in the logic circuit or in the subsystem it supervises) that must be identified experimentally if each of these basic plant phenomena is to be fully understood. We also illustrate the "subsystem incompleteness theorem," which states that no subsystem is operationally self-sufficient. Indeed, a whole-organism perspective is required to understand even the most simple morphogenetic process, because, when isolated, every biological signal-activated subsystem is morphogenetically ineffective. PMID:22645582

  11. Plant Development, Auxin, and the Subsystem Incompleteness Theorem

    PubMed Central

    Niklas, Karl J.; Kutschera, Ulrich

    2012-01-01

    Plant morphogenesis (the process whereby form develops) requires signal cross-talking among all levels of organization to coordinate the operation of metabolic and genomic subsystems operating in a larger network of subsystems. Each subsystem can be rendered as a logic circuit supervising the operation of one or more signal-activated system. This approach simplifies complex morphogenetic phenomena and allows for their aggregation into diagrams of progressively larger networks. This technique is illustrated here by rendering two logic circuits and signal-activated subsystems, one for auxin (IAA) polar/lateral intercellular transport and another for IAA-mediated cell wall loosening. For each of these phenomena, a circuit/subsystem diagram highlights missing components (either in the logic circuit or in the subsystem it supervises) that must be identified experimentally if each of these basic plant phenomena is to be fully understood. We also illustrate the “subsystem incompleteness theorem,” which states that no subsystem is operationally self-sufficient. Indeed, a whole-organism perspective is required to understand even the most simple morphogenetic process, because, when isolated, every biological signal-activated subsystem is morphogenetically ineffective. PMID:22645582

  12. Giada improved calibration of measurement subsystems

    NASA Astrophysics Data System (ADS)

    Della Corte, V.; Rotundi, A.; Sordini, R.; Accolla, M.; Ferrari, M.; Ivanovski, S.; Lucarelli, F.; Mazzotta Epifani, E.; Palumbo, P.

    2014-12-01

    GIADA (Grain Impact Analyzer and Dust Accumulator) is an in-situ instrument devoted to measure the dynamical properties of the dust grains emitted by the comet. An Extended Calibration activity using the GIADA Flight Spare Model has been carried out taking into account the knowledge gained through the analyses of IDPs and cometary samples returned from comet 81P/Wild 2. GIADA consists of three measurement subsystems: Grain Detection System, an optical device measuring the optical cross-section for individual dust; Impact Sensor an aluminum plate connected to 5 piezo-sensors measuring the momentum of impacting single dust grains; Micro Balance System measuring the cumulative deposition in time of dust grains smaller than 10 μm. The results of the analyses on data acquired with the GIADA PFM and the comparison with calibration data acquired during the pre-launch campaign allowed us to improve GIADA performances and capabilities. We will report the results of the following main activities: a) definition of a correlation between the 2 GIADA Models (PFM housed in laboratory and In-Flight Model on-board ROSETTA); b) characterization of the sub-systems performances (signal elaboration, sensitivities, space environment effects); c) new calibration measurements and related curves by means of the PFM model using realistic cometary dust analogues. Acknowledgements: GIADA was built by a consortium led by the Univ. Napoli "Parthenope" & INAF-Oss. Astr. Capodimonte, IT, in collaboration with the Inst. de Astrofisica de Andalucia, ES, Selex-ES s.p.a. and SENER. GIADA is presently managed & operated by Ist. di Astrofisica e Planetologia Spaziali-INAF, IT. GIADA was funded and managed by the Agenzia Spaziale Italiana, IT, with a support of the Spanish Ministry of Education and Science MEC, ES. GIADA was developed from a University of Kent, UK, PI proposal; sci. & tech. contribution given by CISAS, IT, Lab. d'Astr. Spat., FR, and Institutions from UK, IT, FR, DE and USA. We thank

  13. Development of a preprototype times wastewater recovery subsystem: Appendices

    NASA Technical Reports Server (NTRS)

    Roebelen, G. J., Jr.; Dehner, G. F.

    1984-01-01

    This Master Test Plan outlines the test program to be performed by Hamilton Standard during the Urine Water Recovery Subsystem Program. Testing is divided into three phases: (1) design support testing; development component testing; and acceptance testing. The completion of this test program verifies the subsystem operation.

  14. The 30-centimeter ion thrust subsystem design manual

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The principal characteristics of the 30-centimeter ion propulsion thrust subsystem technology that was developed to satisfy the propulsion needs of future planetary and early orbital missions are described. Functional requirements and descriptions, interface and performance requirements, and physical characteristics of the hardware are described at the thrust subsystem, BIMOD engine system, and component level.

  15. Final-Approach-Spacing Subsystem For Air Traffic

    NASA Technical Reports Server (NTRS)

    Davis, Thomas J.; Erzberger, Heinz; Bergeron, Hugh

    1992-01-01

    Automation subsystem of computers, computer workstations, communication equipment, and radar helps air-traffic controllers in terminal radar approach-control (TRACON) facility manage sequence and spacing of arriving aircraft for both efficiency and safety. Called FAST (Final Approach Spacing Tool), subsystem enables controllers to choose among various levels of automation.

  16. Subsystem radiation susceptibility analysis for deep-space missions

    NASA Technical Reports Server (NTRS)

    West, W. S.; Poch, W.; Holmes-Siedle, A.; Bilsky, H. W.; Carroll, D.

    1971-01-01

    Scientific, unmanned spacecraft on mission to Jupiter and beyond will be subjected to nuclear radiation from the natural environment and onboard nuclear power sources which may be harmful to subsystems. This report postulates these environments and discusses practical considerations to ensure confidence that the spacecraft's materials and subsystems will withstand the effects of anticipated radiation. Degradation mechanisms are discussed.

  17. Thermal energy storage subsystems. A collection of quarterly reports

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The design, development, and progress toward the delivery of three subsystems is discussed. The subsystem used a salt hydrate mixture for thermal energy storage. The program schedules, technical data, and other program activities from October 1, 1976, through December 31, 1977 are presented.

  18. OVEN & LAVA Subsystems in the RESOLVE Payload for Resource Prospector

    NASA Technical Reports Server (NTRS)

    Captain, Janine E.

    2015-01-01

    A short briefing in Power Point of the status of the OVEN subsystem and the LAVA subsystems of the RESOLVE payload being developed under the Resource Prospector mission. The purpose of the mission is to sample and analyze volatile ices embedded in the lunar soil at the poles of the Moon and is expected to be conducted in the 2020 time frame.

  19. Does Normal Processing Provide Evidence of Specialised Semantic Subsystems?

    ERIC Educational Resources Information Center

    Shapiro, Laura R.; Olson, Andrew C.

    2005-01-01

    Category-specific disorders are frequently explained by suggesting that living and non-living things are processed in separate subsystems (e.g. Caramazza & Shelton, 1998). If subsystems exist, there should be benefits for normal processing, beyond the influence of structural similarity. However, no previous study has separated the relative…

  20. Triple redundant computer system/display and keyboard subsystem interface

    NASA Technical Reports Server (NTRS)

    Gulde, F. J.

    1973-01-01

    Interfacing of the redundant display and keyboard subsystem with the triple redundant computer system is defined according to space shuttle design. The study is performed in three phases: (1) TRCS configuration and characteristics identification; (2) display and keyboard subsystem configuration and characteristics identification, and (3) interface approach definition.

  1. Digital Controller For Laser-Beam-Steering Subsystem

    NASA Technical Reports Server (NTRS)

    Ansari, Homayoon

    1995-01-01

    Report presents additional information about proposed apparatus described in "Beam-Steering Subsystem for Laser Communication" (NPO-19069). Discusses design of digital beam-steering control subsystem and, in particular, that part of design pertaining to digital compensation for frequency response of steering mirror.

  2. Lessons Learned from the Node 1 Sample Delivery Subsystem Design

    NASA Technical Reports Server (NTRS)

    Williams, David E.

    2007-01-01

    This paper will provide an overview of the International Space Station (ISS) Environmental Control and Life Support (ECLS) design of the Node 1 Sample Delivery Subsystem (SDS) and it will document some of the lessons that have been learned to date for this part of the subsystem.

  3. Multi-Mission Automated Task Invocation Subsystem

    NASA Technical Reports Server (NTRS)

    Cheng, Cecilia S.; Patel, Rajesh R.; Sayfi, Elias M.; Lee, Hyun H.

    2009-01-01

    Multi-Mission Automated Task Invocation Subsystem (MATIS) is software that establishes a distributed data-processing framework for automated generation of instrument data products from a spacecraft mission. Each mission may set up a set of MATIS servers for processing its data products. MATIS embodies lessons learned in experience with prior instrument- data-product-generation software. MATIS is an event-driven workflow manager that interprets project-specific, user-defined rules for managing processes. It executes programs in response to specific events under specific conditions according to the rules. Because requirements of different missions are too diverse to be satisfied by one program, MATIS accommodates plug-in programs. MATIS is flexible in that users can control such processing parameters as how many pipelines to run and on which computing machines to run them. MATIS has a fail-safe capability. At each step, MATIS captures and retains pertinent information needed to complete the step and start the next step. In the event of a restart, this information is retrieved so that processing can be resumed appropriately. At this writing, it is planned to develop a graphical user interface (GUI) for monitoring and controlling a product generation engine in MATIS. The GUI would enable users to schedule multiple processes and manage the data products produced in the processes. Although MATIS was initially designed for instrument data product generation,

  4. Equilibrating temperaturelike variables in jammed granular subsystems.

    PubMed

    Puckett, James G; Daniels, Karen E

    2013-02-01

    Although jammed granular systems are athermal, several thermodynamiclike descriptions have been proposed which make quantitative predictions about the distribution of volume and stress within a system and provide a corresponding temperaturelike variable. We perform experiments with an apparatus designed to generate a large number of independent, jammed, two-dimensional configurations. Each configuration consists of a single layer of photoelastic disks supported by a gentle layer of air. New configurations are generated by cyclically dilating, mixing, and then recompacting the system through a series of boundary displacements. Within each configuration, a bath of particles surrounds a smaller subsystem of particles with a different interparticle friction coefficient than the bath. The use of photoelastic particles permits us to find all particle positions as well as the vector forces at each interparticle contact. By comparing the temperaturelike quantities in both systems, we find compactivity (conjugate to the volume) does not equilibrate between the systems, while the angoricity (conjugate to the stress) does. Both independent components of the angoricity are linearly dependent on the hydrostatic pressure, in agreement with predictions of the stress ensemble. PMID:23414047

  5. Synchronized target subsystem for automated docking systems

    NASA Technical Reports Server (NTRS)

    Howard, Richard T. (Inventor); Book, Michael L. (Inventor); Bryan, Thomas C. (Inventor)

    2000-01-01

    A synchronized target subsystem for use in an automated docking or station keeping system for docking a chase vehicle with a target vehicle wherein the chase vehicle is provided with a video camera which provides adjacent frames each having a predetermined time duration. A light source mounted on the target vehicle flashes at a frequency which has a time duration which is a multiple of the duration time of the frames, the light being on for at least one frame duration and being off for the remainder of the cycle. An image processing unit is connected to the camera for receiving signals from the camera and subtracting one of the adjacent frames from the other to detect whether the light appears in one frame, both frames or neither frame. If the target light appears in both frames or neither frame, the image processing unit feeds a signal to a timing circuit to advance the video camera one frame. This process is continued until the target light appears in one frame and not in the other, at which time the process of advancing the video camera is stopped.

  6. The CALIPSO Integrated Thermal Control Subsystem

    NASA Technical Reports Server (NTRS)

    Gasbarre, Joseph F.; Ousley, Wes; Valentini, Marc; Thomas, Jason; Dejoie, Joel

    2007-01-01

    The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) is a joint NASA-CNES mission to study the Earth's cloud and aerosol layers. The satellite is composed of a primary payload (built by Ball Aerospace) and a spacecraft platform bus (PROTEUS, built by Alcatel Alenia Space). The thermal control subsystem (TCS) for the CALIPSO satellite is a passive design utilizing radiators, multi-layer insulation (MLI) blankets, and both operational and survival surface heaters. The most temperature sensitive component within the satellite is the laser system. During thermal vacuum testing of the integrated satellite, the laser system's operational heaters were found to be inadequate in maintaining the lasers required set point. In response, a solution utilizing the laser system's survival heaters to augment the operational heaters was developed with collaboration between NASA, CNES, Ball Aerospace, and Alcatel-Alenia. The CALIPSO satellite launched from Vandenberg Air Force Base in California on April 26th, 2006. Evaluation of both the platform and payload thermal control systems show they are performing as expected and maintaining the critical elements of the satellite within acceptable limits.

  7. Apollo experience report: Lunar module environmental control subsystem

    NASA Technical Reports Server (NTRS)

    Gillen, R. J.; Brady, J. C.; Collier, F.

    1972-01-01

    A functional description of the environmental control subsystem is presented. Development, tests, checkout, and flight experiences of the subsystem are discussed; and the design fabrication, and operational difficulties associated with the various components and subassemblies are recorded. Detailed information is related concerning design changes made to, and problems encountered with, the various elements of the subsystem, such as the thermal control water sublimator, the carbon dioxide sensing and control units, and the water section. The problems associated with water sterilization, water/glycol formulation, and materials compatibility are discussed. The corrective actions taken are described with the expection that this information may be of value for future subsystems. Although the main experiences described are problem oriented, the subsystem has generally performed satisfactorily in flight.

  8. External orthogonality in subsystem time-dependent density functional theory.

    PubMed

    Chulhai, Dhabih V; Jensen, Lasse

    2016-08-01

    Subsystem density functional theory (subsystem DFT) is a DFT partitioning method that is exact in principle, but depends on approximations to the kinetic energy density functional (KEDF). One may avoid the use of approximate KEDFs by ensuring that the inter-subsystem molecular orbitals are orthogonal, termed external orthogonality (EO). We present a method that extends a subsystem DFT method, that includes EO, into the time-dependent DFT (TDDFT) regime. This method therefore removes the need for approximations to the kinetic energy potential and kernel, and we show that it can accurately reproduce the supermolecular TDDFT results for weakly and strongly coupled subsystems, and for systems with strongly overlapping densities (where KEDF approximations traditionally fail). PMID:26932176

  9. Preliminary systems design study assessment report. Volume 7, Subsystem concepts

    SciTech Connect

    Mayberry, J.L.; Feizollahi, F.; Del Signore, J.C.

    1992-01-01

    The System Design Study (SDS), part of the Waste Technology Development Department at the Idaho National Engineering Laboratory (INEL), examined techniques available for the remediation of hazardous and transuranic waste stored at the Radioactive Waste Management Complex`s Subsurface Disposal Area at the INEL. Using specific technologies, system concepts for treating the buried waste and the surrounding contaminated soil were evaluated. Evaluation included implementability, effectiveness, and cost. The SDS resulted in the development of technology requirements including demonstration, testing, and evaluation activities needed for implementing each. This volume contains the descriptions and other relevant information of the four subsystems required for most of the ex situ processing systems. This volume covers the metal decontamination and sizing subsystem, soils processing subsystem, low-level waste subsystem, and retrieval subsystem.

  10. Assessing Quality across Health Care Subsystems in Mexico

    PubMed Central

    Puig, Andrea; Pagán, José A.; Wong, Rebeca

    2012-01-01

    Recent healthcare reform efforts in Mexico have focused on the need to improve the efficiency and equity of a fragmented healthcare system. In light of these reform initiatives, there is a need to assess whether healthcare subsystems are effective at providing high-quality healthcare to all Mexicans. Nationally representative household survey data from the 2006 Encuesta Nacional de Salud y Nutrición (National Health and Nutrition Survey) were used to assess perceived healthcare quality across different subsystems. Using a sample of 7234 survey respondents, we found evidence of substantial heterogeneity in healthcare quality assessments across healthcare subsystems favoring private providers over social security institutions. These differences across subsystems remained even after adjusting for socioeconomic, demographic, and health factors. Our analysis suggests that improvements in efficiency and equity can be achieved by assessing the factors that contribute to heterogeneity in quality across subsystems. PMID:19305224

  11. MSG Power Subsystem Flight Return Experience

    NASA Astrophysics Data System (ADS)

    Giacometti, G.; Canard, JP.; Perron, O.

    2011-10-01

    The Meteosat programme has been running for more than twenty years under ESA leadership. Meteosat Second Generation (MSG) is a series of 4 geostationary satellites developed and procured by the European Space Agency (ESA) on behalf of the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). Eumetsat is still operating two of the first generation satellites models named MOP3 and MTP1 which are pointed towards the Indian ocean. The European meteorological service is now enhanced by two spacecrafts of the Second Generation (MSG-1 and MSG-2). They have been launched by Ariane 5 in August 2002 and December 2005 respectively. Thales Alenia Space, Prime Contractor of the program, has developed the MSG spacecraft based on a spin-axis stabilized technology. The Electrical Power Subsystem was subcontracted to Astrium GmbH. The Solar Array is composed of 8 body mounted panels, based on Carbon Fibre Reinforced Panel substrate. The Solar network utilizes 7854 Silicon High Eta cells delivering a beginning of life power of 740W. The 28 volts mainbus is regulated using a series shunt regulating concept (S3R type). Two identical SAFT batteries, built from NiCd cells and offering a 29Ah nameplate capacity are connected to the mainbus through battery discharge and charge regulators. Both Solar Array and batteries have been designed to provide power and energy for a nominal 7 years lifetime. These equipments are continuously monitored and are still operating in excellent condition after more than eight and five years in orbit. This paper will present the major electrical design aspects of the power chain and will describe the main parameters performances, which are analysed during the in-orbit operations. Batteries ageing is detailed thanks to reconditioning processed telemetry while the solar array performances over lifetime use dedicated solar array telemetry.

  12. Space shuttle atmospheric revitalization subsystem/active thermal control subsystem computer program (users manual)

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A shuttle (ARS) atmosphere revitalization subsystem active thermal control subsystem (ATCS) performance routine was developed. This computer program is adapted from the Shuttle EC/LSS Design Computer Program. The program was upgraded in three noteworthy areas: (1) The functional ARS/ATCS schematic has been revised to accurately synthesize the shuttle baseline system definition. (2) The program logic has been improved to provide a more accurate prediction of the integrated ARS/ATCS system performance. Additionally, the logic has been expanded to model all components and thermal loads in the ARS/ATCS system. (3) The program is designed to be used on the NASA JSC crew system division's programmable calculator system. As written the new computer routine has an average running time of five minutes. The use of desk top type calculation equipment, and the rapid response of the program provides the NASA with an analytical tool for trade studies to refine the system definition, and for test support of the RSECS or integrated Shuttle ARS/ATCS test programs.

  13. Simulation verification techniques study. Subsystem simulation validation techniques

    NASA Technical Reports Server (NTRS)

    Duncan, L. M.; Reddell, J. P.; Schoonmaker, P. B.

    1974-01-01

    Techniques for validation of software modules which simulate spacecraft onboard systems are discussed. An overview of the simulation software hierarchy for a shuttle mission simulator is provided. A set of guidelines for the identification of subsystem/module performance parameters and critical performance parameters are presented. Various sources of reference data to serve as standards of performance for simulation validation are identified. Environment, crew station, vehicle configuration, and vehicle dynamics simulation software are briefly discussed from the point of view of their interfaces with subsystem simulation modules. A detailed presentation of results in the area of vehicle subsystems simulation modules is included. A list of references, conclusions and recommendations are also given.

  14. Subsystem response review. Seismic Safety Margins Research Program

    SciTech Connect

    Kennedy, R. P.; Campbell, R. D.; Wesley, D. A.; Kamil, H.; Gantayat, A.; Vasudevan, R.

    1981-02-01

    A study was conducted to document the state of the art in seismic qualification of nuclear power plant components and subsystems by analysis and testing and to identify the sources and magnitude of the uncertainties associated with analysis and testing methods. The uncertainties are defined in probabilistic terms for use in probabilistic seismic risk studies. Recommendations are made for the most appropriate subsystem response analysis methods to minimize response uncertainties. Additional studies, to further quantify testing uncertainties, are identified. Although the general effect of non-linearities on subsystem response is discussed, recommendations and conclusions are based principally on linear elastic analysis and testing models.

  15. Development of a preprototype vapor compression distillation water recovery subsystem

    NASA Technical Reports Server (NTRS)

    Johnson, K. L.

    1978-01-01

    The activities involved in the design, development, and test of a preprototype vapor compression distillation water recovery subsystem are described. This subsystem, part of a larger regenerative life support evaluation system, is designed to recover usable water from urine, urinal rinse water, and concentrated shower and laundry brine collected from three space vehicle crewmen for a period of 180 days without resupply. Details of preliminary design and testing as well as component developments are included. Trade studies, considerations leading to concept selections, problems encountered, and test data are also presented. The rework of existing hardware, subsystem development including computer programs, assembly verification, and comprehensive baseline test results are discussed.

  16. A Comprehensive Software Subsystem for Anatomic Pathology and Cytology

    PubMed Central

    Pearson, John M.

    1982-01-01

    An anatomic pathology software subsystem was developed on a Medlab/Control Data Laboratory Computer System. Specifications for such a subsystem included: on-line accessioning, word processing capabilities, automatic retrieval of surgical and cytologic history, SNOMED coding, long-term retrieval by SNOMED code, CAP workload recording and billing. This subsystem has been installed and performing relatively error-free for a number of months. The advantages have just begun to be realized: replacment of log books with on-line access, decreased volume of typing with neater and more consistent reports, a daily surgical pathology log containing each active surgical and related history, and a mechanism for SNOMED searching.

  17. Development of a preprototype times wastewater recovery subsystem

    NASA Technical Reports Server (NTRS)

    Roebelen, G. J., Jr.; Dehner, G. F.

    1982-01-01

    A three-man wastewater recovery preprototype subsystem using a hollow fiber membrane evaporator with a thermoelectric heat pump to provide efficient potable water recovery from wastewater on extended duration space flights was designed, fabricated, and tested at one-gravity. Low power, compactness and gravity insensitive operation are featured in this vacuum distillation subsystem. The tubular hollow fiber elements provide positive liquid/gas phase control with no moving parts, and provide structural integrity, improving on previous flat sheet membrane designs. A thermoelectric heat pump provides latent energy recovery. Application and integration of these key elements solved problems inherent in all previous reclamation subsystem designs.

  18. Subsystem engineering and development of grid-connected photovoltaic systems

    SciTech Connect

    Burgess, E.L.; Post, H.N.; Key, T.S.

    1982-01-01

    The experience gained in fielding residential and intermediate sized photovoltaic application experiments is summarized. This experience is used to guide the engineering and development of array and power conditioning subsystems for grid-connected photovoltaic systems. A major consideration in this development effort is cost. Through innovative engineering, using a modular building block approach for the array subsystem, it is now possible to construct array fields, in moderate quantities, for about $52/m/sup 2/ excluding the photovoltaic modules. Similarly, results of power conditioning subsystem development indicate a projected cost of about $0.25/W/sub p/ for advanced units with conversion efficiencies in excess of 90%.

  19. Apollo experience report: Command and service module controls and displays subsystem

    NASA Technical Reports Server (NTRS)

    Olsen, A. B.; Swint, R. J.

    1976-01-01

    A review of the command and service module controls and displays subsystem is presented. The subsystem is described, and operational requirements, component history, problems and solutions, and conclusions and recommendations for the subsystem are included.

  20. Automated Subsystem Control for Life Support System (ASCLSS)

    NASA Technical Reports Server (NTRS)

    Block, Roger F.

    1987-01-01

    The Automated Subsystem Control for Life Support Systems (ASCLSS) program has successfully developed and demonstrated a generic approach to the automation and control of space station subsystems. The automation system features a hierarchical and distributed real-time control architecture which places maximum controls authority at the lowest or process control level which enhances system autonomy. The ASCLSS demonstration system pioneered many automation and control concepts currently being considered in the space station data management system (DMS). Heavy emphasis is placed on controls hardware and software commonality implemented in accepted standards. The approach demonstrates successfully the application of real-time process and accountability with the subsystem or process developer. The ASCLSS system completely automates a space station subsystem (air revitalization group of the ASCLSS) which moves the crew/operator into a role of supervisory control authority. The ASCLSS program developed over 50 lessons learned which will aide future space station developers in the area of automation and controls..

  1. Ice pack heat sink subsystem - phase 1, volume 2

    NASA Technical Reports Server (NTRS)

    Roebelen, G. J., Jr.

    1973-01-01

    The design, development, and test of a functional laboratory model ice pack heat sink subsystem are discussed. Operating instructions to include mechanical and electrical schematics, maintenance instructions, and equipment specifications are presented.

  2. Development status of a preprototype water electrolysis subsystem

    NASA Technical Reports Server (NTRS)

    Martin, R. B.; Erickson, A. C.

    1981-01-01

    A preprototype water electrolysis subsystem was designed and fabricated for NASA's advanced regenerative life support program. A solid polymer is used for the cell electrolyte. The electrolysis module has 12 cells that can generate 5.5 kg/day of oxygen for the metabolic requirements of three crewmembers, for cabin leakage, and for the oxygen and hydrogen required for carbon dioxide collection and reduction processes. The subsystem can be operated at a pressure between 276 and 2760 kN/sq m and in a continuous constant-current, cyclic, or standby mode. A microprocessor is used to aid in operating the subsystem. Sensors and controls provide fault detection and automatic shutdown. The results of development, demonstration, and parametric testing are presented. Modifications to enhance operation in an integrated and manned test are described. Prospective improvements for the electrolysis subsystem are discussed.

  3. MIUS Integration and Subsystem Test (MIST) data system

    NASA Technical Reports Server (NTRS)

    Pringle, L. M.

    1977-01-01

    A data system for use in testing integrated subsystems of a modular integrated utility system (MIUS) is presented. The MIUS integration and subsystem test (MIST) data system is reviewed from its conception through its checkout and operation as the controlling portion of the MIST facility. The MIST data system provides a real time monitoring and control function that allows for complete evaluation of the performance of the mechanical and electrical subsystems, as well as controls the operation of the various components of the system. In addition to the aforementioned capabilities, the MIST data system provides computerized control of test operations such that minimum manpower is necessary to set up, operate, and shut down subsystems during test periods.

  4. Double Shell Tank (DST) Process Waste Sampling Subsystem Specification

    SciTech Connect

    RASMUSSEN, J.H.

    2000-05-03

    This specification establishes the performance requirements and provides references to the requisite codes and standards to be applied to the Double-Shell Tank (DST) Process Waste Sampling Subsystem which supports the first phase of Waste Feed Delivery.

  5. Automated biowaste sampling system, solids subsystem operating model, part 2

    NASA Technical Reports Server (NTRS)

    Fogal, G. L.; Mangialardi, J. K.; Stauffer, R. E.

    1973-01-01

    The detail design and fabrication of the Solids Subsystem were implemented. The system's capacity for the collection, storage or sampling of feces and vomitus from six subjects was tested and verified.

  6. Development of Pattern Recognition Options for Combining Safeguards Subsystems

    SciTech Connect

    Burr, Thomas L.; Hamada, Michael S.

    2012-08-24

    This talk reviews project progress in combining process monitoring data and nuclear material accounting data to improve the over nuclear safeguards system. Focus on 2 subsystems: (1) nuclear materials accounting (NMA); and (2) process monitoring (PM).

  7. Subsystem fact sheets for NASA CO2 Project, revision 3

    NASA Technical Reports Server (NTRS)

    Lookabaugh, T.

    1985-01-01

    The twenty-seven subsystem fact sheets produced by Ball Aerospace Systems Division are presented. Each instrument is summarized with a description; physical characteristics; data; orbit requirements; sensor; implementation schedule; and experience, problems, modifications.

  8. Pilot climate data system: User's guide for charts subsystem

    NASA Technical Reports Server (NTRS)

    Noll, C. E.

    1984-01-01

    The use of the Pilot Climate Data System's (PCDS) CHARTS Subsystem is described. This facility is an interactive software system for the graphical production and enhancement of text and viewgraph displays.

  9. Double Shell Tank (DST) Monitor and Control Subsystem Specification

    SciTech Connect

    BAFUS, R.R.

    2000-11-03

    This specification revises the performance requirements and provides references to the requisite codes and standards to be applied during design of the Double-Shell Tank (DST) Monitor and Control Subsystem that supports the first phase of Waste Feed Delivery.

  10. Overview of the OSIRIS-REx Parachute Recovery Subsystem

    NASA Astrophysics Data System (ADS)

    Reza, S.; Rowan, J.; Witkowski, A.

    2014-06-01

    A general overview of the planned Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer (OSIRIS-REx) parachute recovery subsystem, to include modifications to the Stardust design and design and testing of a new PRS mortar.

  11. Power Subsystem for Extravehicular Activities for Exploration Missions

    NASA Technical Reports Server (NTRS)

    Manzo, Michelle

    2005-01-01

    The NASA Glenn Research Center has the responsibility to develop the next generation space suit power subsystem to support the Vision for Space Exploration. Various technology challenges exist in achieving extended duration missions as envisioned for future lunar and Mars mission scenarios. This paper presents an overview of ongoing development efforts undertaken at the Glenn Research Center in support of power subsystem development for future extravehicular activity systems.

  12. Prototype Bosch CO2 reduction subsystem for the RLSE experiment

    NASA Technical Reports Server (NTRS)

    Heppner, D. B.; Wynveen, R. A.; Schubert, F. H.

    1977-01-01

    Requirements for the Bosch carbon dioxide reduction subsystem were established in a study of regenerative life support evaluation experiments. A detailed design is presented including a schematic, components list and characteristics, requirements summaries, and complete definition of life systems' advanced control/monitor instrumentation applied to the Bosch subsystem. Design information needed to proceed with the final design and fabrication of a preprototype system is presented.

  13. Statistical Design Model (SDM) of satellite thermal control subsystem

    NASA Astrophysics Data System (ADS)

    Mirshams, Mehran; Zabihian, Ehsan; Aarabi Chamalishahi, Mahdi

    2016-07-01

    Satellites thermal control, is a satellite subsystem that its main task is keeping the satellite components at its own survival and activity temperatures. Ability of satellite thermal control plays a key role in satisfying satellite's operational requirements and designing this subsystem is a part of satellite design. In the other hand due to the lack of information provided by companies and designers still doesn't have a specific design process while it is one of the fundamental subsystems. The aim of this paper, is to identify and extract statistical design models of spacecraft thermal control subsystem by using SDM design method. This method analyses statistical data with a particular procedure. To implement SDM method, a complete database is required. Therefore, we first collect spacecraft data and create a database, and then we extract statistical graphs using Microsoft Excel, from which we further extract mathematical models. Inputs parameters of the method are mass, mission, and life time of the satellite. For this purpose at first thermal control subsystem has been introduced and hardware using in the this subsystem and its variants has been investigated. In the next part different statistical models has been mentioned and a brief compare will be between them. Finally, this paper particular statistical model is extracted from collected statistical data. Process of testing the accuracy and verifying the method use a case study. Which by the comparisons between the specifications of thermal control subsystem of a fabricated satellite and the analyses results, the methodology in this paper was proved to be effective. Key Words: Thermal control subsystem design, Statistical design model (SDM), Satellite conceptual design, Thermal hardware

  14. Technology for subsystems of space-based plant growth facilities

    NASA Technical Reports Server (NTRS)

    Bula, R. J.; Morrow, R. C.; Tibbitts, T. W.; Corey, R. B.

    1990-01-01

    Technologies for different subsystems of space-based plant growth facilities are being developed at the Wisconsin Center for Space Automation and Robotics, a NASA Center for the Commercial Development of Space. The technologies include concepts for water and nutrient delivery, for nutrient composition control, and for irradiation. Effort is being concentrated on these subsystems because available technologies cannot be effectively utilized for space applications.

  15. STS-2: SAIL non-avionics subsystems math model requirements

    NASA Technical Reports Server (NTRS)

    Bennett, W. P.; Herold, R. W.

    1980-01-01

    Simulation of the STS-2 Shuttle nonavionics subsystems in the shuttle avionics integration laboratory (SAIL) is necessary for verification of the integrated shuttle avionics system. The math model (simulation) requirements for each of the nonavionics subsystems that interfaces with the Shuttle avionics system is documented and a single source document for controlling approved changes (by the SAIL change control panel) to the math models is provided.

  16. Opto-mechanical subsystem with temperature compensation through isothemal design

    NASA Technical Reports Server (NTRS)

    Goodwin, F. E. (Inventor)

    1977-01-01

    An opto-mechanical subsystem for supporting a laser structure which minimizes changes in the alignment of the laser optics in response to temperature variations is described. Both optical and mechanical structural components of the system are formed of the same material, preferably beryllium, which is selected for high mechanical strength and good thermal conducting qualities. All mechanical and optical components are mounted and assembled to provide thorough thermal coupling throughout the subsystem to prevent the development of temperature gradients.

  17. An Algorithm for Integrated Subsystem Embodiment and System Synthesis

    NASA Technical Reports Server (NTRS)

    Lewis, Kemper

    1997-01-01

    Consider the statement,'A system has two coupled subsystems, one of which dominates the design process. Each subsystem consists of discrete and continuous variables, and is solved using sequential analysis and solution.' To address this type of statement in the design of complex systems, three steps are required, namely, the embodiment of the statement in terms of entities on a computer, the mathematical formulation of subsystem models, and the resulting solution and system synthesis. In complex system decomposition, the subsystems are not isolated, self-supporting entities. Information such as constraints, goals, and design variables may be shared between entities. But many times in engineering problems, full communication and cooperation does not exist, information is incomplete, or one subsystem may dominate the design. Additionally, these engineering problems give rise to mathematical models involving nonlinear functions of both discrete and continuous design variables. In this dissertation an algorithm is developed to handle these types of scenarios for the domain-independent integration of subsystem embodiment, coordination, and system synthesis using constructs from Decision-Based Design, Game Theory, and Multidisciplinary Design Optimization. Implementation of the concept in this dissertation involves testing of the hypotheses using example problems and a motivating case study involving the design of a subsonic passenger aircraft.

  18. The Advanced Composition Explorer power subsystem

    SciTech Connect

    Panneton, P.E.; Tarr, J.E.; Goliaszewski, L.T.

    1998-07-01

    The Johns Hopkins University Applied Physics Laboratory, under contract with NASA Goddard Space Flight Center, has designed and launched the Advanced Composition Explorer (ACE) spacecraft. ACE is a scientific observatory housing ten instruments, and is located in a halo orbit about the L1 Sun-Earth libration point. ACE is providing real-time solar wind monitoring and data on elemental and isotopic matter of solar and galactic origin. The ACE Electrical Power Subsystem (EPS) is a fault tolerant, solar powered, shunt regulated, direct energy transfer architecture based on the Midcourse Space Experiment (MSX) EPS. The differences are that MSX used oriented solar arrays with a nickel hydrogen-battery defined bus, while ACE uses fixed solar panels with a regulated bus decoupled from its nickel cadmium (NiCd) battery. Also, magnetometer booms are mounted on two of the four ACE solar panels. The required accuracy of the magnetometers impose severe requirements on the magnetic fields induced by the solar array. Other noteworthy features include a solar cell degradation experiment, in-flight battery reconditioning, a battery requalified to a high vibrational environment, and an adjustable bus voltage setpoint. The four solar panels consist of aluminum honeycomb substrates covered with 15.1% efficient silicon cells. The cells are strung using silver interconnects and are back-wired to reduce magnetic emissions below 0.1nT. Pyrotechnic actuated, spring loaded hinges deploy the panels after spacecraft separation from the Delta II launch vehicle. Solar cell experiments on two of the panels track cell performance degradation at L1, and also distinguish any hydrazine impingement degradation which may be caused by the thrusters. Each solar panel uses a digital shunt box, containing blocking diodes and MOSFETs, for short-circuit control of its 5 solar strings. A power box contains redundant analog MOSFET shunts, the 90% efficient boost regulator, and redundant battery chargers

  19. Planning and Execution for an Autonomous Aerobot

    NASA Technical Reports Server (NTRS)

    Gaines, Daniel M.; Estlin, Tara A.; Schaffer, Steven R.; Chouinard, Caroline M.

    2010-01-01

    The Aerial Onboard Autonomous Science Investigation System (AerOASIS) system provides autonomous planning and execution capabilities for aerial vehicles (see figure). The system is capable of generating high-quality operations plans that integrate observation requests from ground planning teams, as well as opportunistic science events detected onboard the vehicle while respecting mission and resource constraints. AerOASIS allows an airborne planetary exploration vehicle to summarize and prioritize the most scientifically relevant data; identify and select high-value science sites for additional investigation; and dynamically plan, schedule, and monitor the various science activities being performed, even during extended communications blackout periods with Earth.

  20. Double Shell Tank (DST) Monitor and Control Subsystem Specification

    SciTech Connect

    BAFUS, R.R.

    2000-04-27

    This specification establishes the performance requirements and provides references to the requisite codes and standards to be applied during design of the Double-Shell Tank (DST) Monitor and Control Subsystem that supports the first phase of Waste Feed Delivery. This subsystem specification establishes the interface and performance requirements and provides references to the requisite codes and standards to be applied during the design of the Double-Shell Tank (DST) Monitor and Control Subsystem. The DST Monitor and Control Subsystem consists of the new and existing equipment that will be used to provide tank farm operators with integrated local monitoring and control of the DST systems to support Waste Feed Delivery (WFD). New equipment will provide automatic control and safety interlocks where required and provide operators with visibility into the status of DST subsystem operations (e.g., DST mixer pump operation and DST waste transfers) and the ability to manually control specified DST functions as necessary. This specification is intended to be the basis for new project/installations (W-521, etc.). This specification is not intended to retroactively affect previously established project design criteria without specific direction by the program.

  1. Preprototype vapor compression distillation subsystem. [recovering potable water from wastewater

    NASA Technical Reports Server (NTRS)

    Ellis, G. S.; Wynveen, R. A.; Schubert, F. H.

    1979-01-01

    A three-person capacity preprototype vapor compression distillation subsystem for recovering potable water from wastewater aboard spacecraft was designed, assembled, and tested. The major components of the subsystem are: (1) a distillation unit which includes a compressor, centrifuge, central shaft, and outer shell; (2) a purge pump; (3) a liquids pump; (4) a post-treat cartridge; (5) a recycle/filter tank; (6) an evaporator high liquid level sensor; and (7) the product water conductivity monitor. A computer based control monitor instrumentation carries out operating mode change sequences, monitors and displays subsystem parameters, maintains intramode controls, and stores and displays fault detection information. The mechanical hardware occupies 0.467 m3, requires 171 W of electrical power, and has a dry weight of 143 kg. The subsystem recovers potable water at a rate of 1.59 kg/hr, which is equivalent to a duty cycle of approximately 30% for a crew of three. The product water has no foul taste or odor. Continued development of the subsystem is recommended for reclaiming water for human consumption as well as for flash evaporator heat rejection, urinal flushing, washing, and other on-board water requirements.

  2. The monopropellant hydrazine propulsion subsystem for the Pioneer Venus spacecraft

    NASA Technical Reports Server (NTRS)

    Barker, F. C.

    1979-01-01

    The Pioneer Venus Orbiter and the Multiprobe spacecraft propulsion subsystems and their performance are presented. Monopropellant hydrazine subsystems on each spacecraft provided the capability to spin up the spacecraft after separation and perform all spin rate, velocity, and attitude changes required by the control subsystem to satisfy mission objectives. The propulsion subsystem provides thrust on demand by supplying anhydrous hydrazine from the propellant tanks through manifolds, filters and valves to the thrust chamber assemblies where the hydrazine is catalytically decomposed and expanded in a conical nozzle. The subsystems consist of seven 1 lbf thrusters for the Orbiter and six 1 lbf thrusters for the multiprobe which are isolated by two latch valves from the two propellant tanks so that two redundant thruster clusters are provided to ensure mission completion in the event of a single point failure. The propellant feed system is of all-welded construction to minimize weight and leakage and titanium is used as the primary material of construction. The multiprobe burned up on entering the Venus atmosphere with enough propellant left for the mission and the Orbiter was inserted into Venus orbit with enough propellant remaining for more than 2 earth years of orbital operations.

  3. On the description of subsystems in relativistic hypersurface Bohmian mechanics

    PubMed Central

    Dürr, Detlef; Lienert, Matthias

    2014-01-01

    A candidate for a realistic relativistic quantum theory is the hypersurface Bohm–Dirac model. Its formulation uses a foliation of space–time into space-like hypersurfaces. In order to apply the theory and to make contact with the usual quantum formalism, one needs a framework for the description of subsystems. The presence of spin together with the foliation renders the subsystem description more complicated than in the non-relativistic case with spin. In this paper, we provide such a framework in terms of an appropriate conditional density matrix and an effective wave function as well as clarify their relation, thereby generalizing previous subsystem descriptions in the non-relativistic case. PMID:25197244

  4. Mathematical modeling of control subsystems for CELSS: Application to diet

    NASA Technical Reports Server (NTRS)

    Waleh, Ahmad; Nguyen, Thoi K.; Kanevsky, Valery

    1991-01-01

    The dynamic control of a Closed Ecological Life Support System (CELSS) in a closed space habitat is of critical importance. The development of a practical method of control is also a necessary step for the selection and design of realistic subsystems and processors for a CELSS. Diet is one of the dynamic factors that strongly influences, and is influenced, by the operational states of all major CELSS subsystems. The problems of design and maintenance of a stable diet must be obtained from well characterized expert subsystems. The general description of a mathematical model that forms the basis of an expert control program for a CELSS is described. The formulation is expressed in terms of a complete set of time dependent canonical variables. System representation is dynamic and includes time dependent storage buffers. The details of the algorithm are described. The steady state results of the application of the method for representative diets made from wheat, potato, and soybean are presented.

  5. Modular thrust subsystem approaches to solar electric propulsion module design

    NASA Technical Reports Server (NTRS)

    Cake, J. E.; Sharp, G. R.; Oglebay, J. C.; Shaker, F. J.; Zevesky, R. J.

    1976-01-01

    Three approaches are presented for packaging the elements of a 30 cm ion thrustor subsystem into a modular thrust subsystem. The individual modules, when integrated into a conceptual solar electric propulsion module are applicable to a multimission set of interplanetary flights with the Space Shuttle/Interim Upper Stage as the launch vehicle. The emphasis is on the structural and thermal integration of the components into the modular thrust subsystems. Thermal control for the power processing units is either by direct radiation through louvers in combination with heat pipes of an all heat pipe system. The propellant storage and feed system and thrustor gimbal system concepts are presented. The three approaches are compared on the basis of mass, cost, testing, interfaces, simplicity, reliability, and maintainability.

  6. Ice pack heat sink subsystem - Phase 1, Volume 1

    NASA Technical Reports Server (NTRS)

    Roebelen, G. J., Jr.

    1973-01-01

    The design, development, fabrication, and test at one-g of a functional laboratory model (non-flight) ice pack heat sink subsystem to be used eventually for astronaut cooling during manned space missions are discussed. In normal use, excess heat in the liquid cooling garment (LCG) coolant is transferred to a reusable/regenerable ice pack heat sink. For emergency operation, or for extension of extravehicular activity mission time after all the ice has melted, water from the ice pack is boiled to vacuum, thereby continuing to remove heat from the LCG coolant. This subsystem incorporates a quick connect/disconnect thermal interface between the ice pack heat sink and the subsystem heat exchanger.

  7. An automated environment for multiple spacecraft engineering subsystem mission operations

    NASA Technical Reports Server (NTRS)

    Bahrami, K. A.; Hioe, K.; Lai, J.; Imlay, E.; Schwuttke, U.; Hsu, E.; Mikes, S.

    1990-01-01

    Flight operations at the Jet Propulsion Laboratory (JPL) are now performed by teams of specialists, each team dedicated to a particular spacecraft. Certain members of each team are responsible for monitoring the performances of their respective spacecraft subsystems. Ground operations, which are very complex, are manual, labor-intensive, slow, and tedious, and therefore costly and inefficient. The challenge of the new decade is to operate a large number of spacecraft simultaneously while sharing limited human and computer resources, without compromising overall reliability. The Engineering Analysis Subsystem Environment (EASE) is an architecture that enables fewer controllers to monitor and control spacecraft engineering subsystems. A prototype of EASE has been installed in the JPL Space Flight Operations Facility for on-line testing. This article describes the underlying concept, development, testing, and benefits of the EASE prototype.

  8. Double Shell Tank (DST) Transfer Piping Subsystem Specification

    SciTech Connect

    GRAVES, C.E.

    2000-03-22

    This specification establishes the performance requirements and provides references to the requisite codes and standards to be applied during design of the Double-Shell Tank (DST) Transfer Piping Subsystem that supports the first phase of Waste Feed Delivery. This specification establishes the performance requirements and provides references to the requisite codes and standards to be applied during design of the Double-Shell Tank (DST) Transfer Piping Subsystem that supports the first phase of waste feed delivery. This subsystem transfers waste between transfer-associated structures (pits) and to the River Protection Project (RPP) Privatization Contractor Facility where it will be processed into an immobilized waste form. This specification is intended to be the basis for new projects/installations (W-521, etc.). This specification is not intended to retroactively affect previously established project design criteria without specific direction by the program.

  9. Subsystem real-time time dependent density functional theory

    NASA Astrophysics Data System (ADS)

    Krishtal, Alisa; Ceresoli, Davide; Pavanello, Michele

    2015-04-01

    We present the extension of Frozen Density Embedding (FDE) formulation of subsystem Density Functional Theory (DFT) to real-time Time Dependent Density Functional Theory (rt-TDDFT). FDE is a DFT-in-DFT embedding method that allows to partition a larger Kohn-Sham system into a set of smaller, coupled Kohn-Sham systems. Additional to the computational advantage, FDE provides physical insight into the properties of embedded systems and the coupling interactions between them. The extension to rt-TDDFT is done straightforwardly by evolving the Kohn-Sham subsystems in time simultaneously, while updating the embedding potential between the systems at every time step. Two main applications are presented: the explicit excitation energy transfer in real time between subsystems is demonstrated for the case of the Na4 cluster and the effect of the embedding on optical spectra of coupled chromophores. In particular, the importance of including the full dynamic response in the embedding potential is demonstrated.

  10. On the description of subsystems in relativistic hypersurface Bohmian mechanics.

    PubMed

    Dürr, Detlef; Lienert, Matthias

    2014-09-01

    A candidate for a realistic relativistic quantum theory is the hypersurface Bohm-Dirac model. Its formulation uses a foliation of space-time into space-like hypersurfaces. In order to apply the theory and to make contact with the usual quantum formalism, one needs a framework for the description of subsystems. The presence of spin together with the foliation renders the subsystem description more complicated than in the non-relativistic case with spin. In this paper, we provide such a framework in terms of an appropriate conditional density matrix and an effective wave function as well as clarify their relation, thereby generalizing previous subsystem descriptions in the non-relativistic case. PMID:25197244

  11. Modular thrust subsystem approaches to solar electric propulsion module design

    NASA Technical Reports Server (NTRS)

    Cake, J. E.; Sharp, G. R.; Oglebay, J. C.; Shaker, F. J.; Zavesky, R. J.

    1976-01-01

    Three approaches are presented for packaging the elements of a 30 cm ion thruster subsystem into a modular thrust subsystem. The individual modules, when integrated into a conceptual solar electric propulsion module are applicable to a multimission set of interplanetary flights with the space shuttle interim upper stage as the launch vehicle. The emphasis is on the structural and thermal integration of the components into the modular thrust subsystems. Thermal control for the power processing units is either by direct radiation through louvers in combination with heat pipes or an all heat pipe system. The propellant storage and feed system and thruster gimbal system concepts are presented. The three approaches are compared on the basis of mass, cost, testing, interfaces, simplicity, reliability, and maintainability.

  12. The complete Heyting algebra of subsystems and contextuality

    SciTech Connect

    Vourdas, A.

    2013-08-15

    The finite set of subsystems of a finite quantum system with variables in Z(n), is studied as a Heyting algebra. The physical meaning of the logical connectives is discussed. It is shown that disjunction of subsystems is more general concept than superposition. Consequently, the quantum probabilities related to commuting projectors in the subsystems, are incompatible with associativity of the join in the Heyting algebra, unless if the variables belong to the same chain. This leads to contextuality, which in the present formalism has as contexts, the chains in the Heyting algebra. Logical Bell inequalities, which contain “Heyting factors,” are discussed. The formalism is also applied to the infinite set of all finite quantum systems, which is appropriately enlarged in order to become a complete Heyting algebra.

  13. Embedded Thermal Control for Subsystems for Next Generation Spacecraft Applications

    NASA Technical Reports Server (NTRS)

    Didion, Jeffrey R.

    2015-01-01

    Thermal Fluids and Analysis Workshop, Silver Spring MD NCTS 21070-15. NASA, the Defense Department and commercial interests are actively engaged in developing miniaturized spacecraft systems and scientific instruments to leverage smaller cheaper spacecraft form factors such as CubeSats. This paper outlines research and development efforts among Goddard Space Flight Center personnel and its several partners to develop innovative embedded thermal control subsystems. Embedded thermal control subsystems is a cross cutting enabling technology integrating advanced manufacturing techniques to develop multifunctional intelligent structures to reduce Size, Weight and Power (SWaP) consumption of both the thermal control subsystem and overall spacecraft. Embedded thermal control subsystems permit heat acquisition and rejection at higher temperatures than state of the art systems by employing both advanced heat transfer equipment (integrated heat exchangers) and high heat transfer phenomena. The Goddard Space Flight Center Thermal Engineering Branch has active investigations seeking to characterize advanced thermal control systems for near term spacecraft missions. The embedded thermal control subsystem development effort consists of fundamental research as well as development of breadboard and prototype hardware and spaceflight validation efforts. This paper will outline relevant fundamental investigations of micro-scale heat transfer and electrically driven liquid film boiling. The hardware development efforts focus upon silicon based high heat flux applications (electronic chips, power electronics etc.) and multifunctional structures. Flight validation efforts include variable gravity campaigns and a proposed CubeSat based flight demonstration of a breadboard embedded thermal control system. The CubeSat investigation is technology demonstration will characterize in long-term low earth orbit a breadboard embedded thermal subsystem and its individual components to develop

  14. Interface Supports Lightweight Subsystem Routing for Flight Applications

    NASA Technical Reports Server (NTRS)

    Lux, James P.; Block, Gary L.; Ahmad, Mohammad; Whitaker, William D.; Dillon, James W.

    2010-01-01

    A wireless avionics interface exploits the constrained nature of data networks in flight systems to use a lightweight routing method. This simplified routing means that a processor is not required, and the logic can be implemented as an intellectual property (IP) core in a field-programmable gate array (FPGA). The FPGA can be shared with the flight subsystem application. In addition, the router is aware of redundant subsystems, and can be configured to provide hot standby support as part of the interface. This simplifies implementation of flight applications requiring hot stand - by support. When a valid inbound packet is received from the network, the destination node address is inspected to determine whether the packet is to be processed by this node. Each node has routing tables for the next neighbor node to guide the packet to the destination node. If it is to be processed, the final packet destination is inspected to determine whether the packet is to be forwarded to another node, or routed locally. If the packet is local, it is sent to an Applications Data Interface (ADI), which is attached to a local flight application. Under this scheme, an interface can support many applications in a subsystem supporting a high level of subsystem integration. If the packet is to be forwarded to another node, it is sent to the outbound packet router. The outbound packet router receives packets from an ADI or a packet to be forwarded. It then uses a lookup table to determine the next destination for the packet. Upon detecting a remote subsystem failure, the routing table can be updated to autonomously bypass the failed subsystem.

  15. Virtual Engineering and Science Team - Reusable Autonomy for Spacecraft Subsystems

    NASA Technical Reports Server (NTRS)

    Bailin, Sidney C.; Johnson, Michael A.; Rilee, Michael L.; Truszkowski, Walt; Thompson, Bryan; Day, John H. (Technical Monitor)

    2002-01-01

    In this paper we address the design, development, and evaluation of the Virtual Engineering and Science Team (VEST) tool - a revolutionary way to achieve onboard subsystem/instrument autonomy. VEST directly addresses the technology needed for advanced autonomy enablers for spacecraft subsystems. It will significantly support the efficient and cost effective realization of on-board autonomy and contribute directly to realizing the concept of an intelligent autonomous spacecraft. VEST will support the evolution of a subsystem/instrument model that is probably correct and from that model the automatic generation of the code needed to support the autonomous operation of what was modeled. VEST will directly support the integration of the efforts of engineers, scientists, and software technologists. This integration of efforts will be a significant advancement over the way things are currently accomplished. The model, developed through the use of VEST, will be the basis for the physical construction of the subsystem/instrument and the generated code will support its autonomous operation once in space. The close coupling between the model and the code, in the same tool environment, will help ensure that correct and reliable operational control of the subsystem/instrument is achieved.VEST will provide a thoroughly modern interface that will allow users to easily and intuitively input subsystem/instrument requirements and visually get back the system's reaction to the correctness and compatibility of the inputs as the model evolves. User interface/interaction, logic, theorem proving, rule-based and model-based reasoning, and automatic code generation are some of the basic technologies that will be brought into play in realizing VEST.

  16. Novel Design Aspects of the Space Technology 5 Mechanical Subsystem

    NASA Technical Reports Server (NTRS)

    Rossoni, Peter; McGill, William

    2003-01-01

    This paper describes several novel design elements of the Space Technology 5 (ST5) spacecraft mechanical subsystem. The spacecraft structure itself takes a significant step in integrating electronics into the primary structure. The deployment system restrains the spacecraft during launch and imparts a predetermined spin rate upon release from its secondary payload accommodations. The deployable instrument boom incorporates some traditional as well as new techniques for lightweight and stiffness. Analysis and test techniques used to validate these technologies are described. Numerous design choices were necessitated due to the compact spacecraft size and strict mechanical subsystem requirements.

  17. Challenges in the development of the orbiter atmosphere revitalization subsystem

    NASA Technical Reports Server (NTRS)

    Prince, R. N.; Swider, J.; Wojnarowski, J.; Decrisantis, A.; Ord, G. R.; Walleshauser, J. J.; Gibb, J. W.

    1985-01-01

    The space shuttle orbiter atmospheric revitalization subsystem provides thermal and contaminant control as well as total- and oxygen partial-pressure control of the environment within the orbiter crew cabin. Challenges that occurred during the development of this subsystem for the space shuttle orbiter are described. The design of the rotating hardware elements of the system (pumps, fans, etc.) required significant development to meet the requirements of long service life, maintainability, and high cycle-fatigue life. As a result, a stringent development program, particularly in the areas of bearing life and heat dissipation, was required. Another area requiring significant development was cabin humidity control and condensate collection.

  18. Solar electric propulsion/instrument/subsystems interaction study

    NASA Technical Reports Server (NTRS)

    Sellen, J. M., Jr.; Cole, R. K.; Kemp, R. F.; Hall, D. F.; Shelton, H.

    1973-01-01

    The interactive effects between a solar electric propulsion system and an electrically propelled scientific spacecraft were examined. The operation of the ion thrusters may impact upon the acquisition and interpretation of data by the science payload of the spacecraft. The effluents from the operation of the electric propulsion unit may also impact upon the operation of the various subsystems of the vehicle. Specific interactive effects were isolated where meaningful levels of interaction may occur. The level of impact upon elements of the science payload and other affected subsystems is examined, and avenues for the reduction or elimination of impact are defined.

  19. Statistical error model for a solar electric propulsion thrust subsystem

    NASA Technical Reports Server (NTRS)

    Bantell, M. H.

    1973-01-01

    The solar electric propulsion thrust subsystem statistical error model was developed as a tool for investigating the effects of thrust subsystem parameter uncertainties on navigation accuracy. The model is currently being used to evaluate the impact of electric engine parameter uncertainties on navigation system performance for a baseline mission to Encke's Comet in the 1980s. The data given represent the next generation in statistical error modeling for low-thrust applications. Principal improvements include the representation of thrust uncertainties and random process modeling in terms of random parametric variations in the thrust vector process for a multi-engine configuration.

  20. Apollo experience report: Lunar module landing gear subsystem

    NASA Technical Reports Server (NTRS)

    Rogers, W. F.

    1972-01-01

    The development of the lunar module landing gear subsystem through the Apollo 11 lunar landing mission is presented. The landing gear design evolved from the design requirement, which had to satisfy the structural, mechanical, and landing performance constraints of the vehicle. Extensive analyses and tests were undertaken to verify the design adequacy. Techniques of the landing performance analysis served as a primary tool in developing the subsystem hardware and in determining the adequacy of the landing gear for toppling stability and energy absorption. The successful Apollo 11 lunar landing mission provided the first opportunity for a complete flight test of the landing gear under both natural and induced environments.

  1. Apollo experience report: Crew provisions and equipment subsystem

    NASA Technical Reports Server (NTRS)

    Mcallister, F.

    1972-01-01

    A description of the construction and use of crew provisions and equipment subsystem items for the Apollo Program is presented. The subsystem is composed principally of survival equipment, bioinstrumentation devices, medical components and accessories, water- and waste-management equipment, personal-hygiene articles, docking aids, flight garments (excluding the pressure garment assembly), and various other crew-related accessories. Particular attention is given to items and assemblies that presented design, development, or performance problems: the crew optical alinement sight system, the metering water dispenser, and the waste-management system. Changes made in design and materials to improve the fire safety of the hardware are discussed.

  2. Software Testbed for Developing and Evaluating Integrated Autonomous Subsystems

    NASA Technical Reports Server (NTRS)

    Ong, James; Remolina, Emilio; Prompt, Axel; Robinson, Peter; Sweet, Adam; Nishikawa, David

    2015-01-01

    To implement fault tolerant autonomy in future space systems, it will be necessary to integrate planning, adaptive control, and state estimation subsystems. However, integrating these subsystems is difficult, time-consuming, and error-prone. This paper describes Intelliface/ADAPT, a software testbed that helps researchers develop and test alternative strategies for integrating planning, execution, and diagnosis subsystems more quickly and easily. The testbed's architecture, graphical data displays, and implementations of the integrated subsystems support easy plug and play of alternate components to support research and development in fault-tolerant control of autonomous vehicles and operations support systems. Intelliface/ADAPT controls NASA's Advanced Diagnostics and Prognostics Testbed (ADAPT), which comprises batteries, electrical loads (fans, pumps, and lights), relays, circuit breakers, invertors, and sensors. During plan execution, an experimentor can inject faults into the ADAPT testbed by tripping circuit breakers, changing fan speed settings, and closing valves to restrict fluid flow. The diagnostic subsystem, based on NASA's Hybrid Diagnosis Engine (HyDE), detects and isolates these faults to determine the new state of the plant, ADAPT. Intelliface/ADAPT then updates its model of the ADAPT system's resources and determines whether the current plan can be executed using the reduced resources. If not, the planning subsystem generates a new plan that reschedules tasks, reconfigures ADAPT, and reassigns the use of ADAPT resources as needed to work around the fault. The resource model, planning domain model, and planning goals are expressed using NASA's Action Notation Modeling Language (ANML). Parts of the ANML model are generated automatically, and other parts are constructed by hand using the Planning Model Integrated Development Environment, a visual Eclipse-based IDE that accelerates ANML model development. Because native ANML planners are currently

  3. The general rescue subsystem-adaptation and structure at sea

    SciTech Connect

    Skyttner, L.

    1992-12-31

    The existence of a general rescue subsystem in higher organisms, as part of the GLS theory and the GAS syndrome, is asserted. Working principle for the system and its existence throughout higher system levels are presented. Among important processes demonstrated are the adaptation of the system to special threats at sea and the storage of the system knowledge and organization in the sea-safety convention. Recursiveness of the rescue subsystem within all higher system levels was found to be a basic requisite for individual survival, especially at sea. Finally, the most serious threat to lives on board ships at sea, was found to be system morality failures. 12 refs.

  4. Development of a preprototype times wastewater recovery subsystem, addendum

    NASA Technical Reports Server (NTRS)

    Dehner, G. F.

    1984-01-01

    Six tasks are described reflecting subsystem hardware and software modifications and test evaluation of a TIMES wastewater recovery subsystem. The overall results are illustrated in a figure which shows the water production rate, the specific energy corrected to 26.5 VDC, and the product water conductivity at various points in the testing. Four tasks are described reflecting studies performed to develop a preliminary design concept for a next generation TIMES. The overall results of the study are the completion of major design analyses and preliminary configuration layout drawings.

  5. Galileo attitude and articulation control subsystem closed loop testing

    NASA Technical Reports Server (NTRS)

    Lembeck, M. F.; Pignatano, N. D.

    1983-01-01

    In order to ensure the reliable operation of the Attitude and Articulation Control Subsystem (AACS) which will guide the Galileo spacecraft on its two and one-half year journey to Jupiter, the AACS is being rigorously tested. The primary objectives of the test program are the verification of the AACS's form, fit, and function, especially with regard to subsystem external interfaces and the functional operation of the flight software. Attention is presently given to the Galileo Closed Loop Test System, which simulates the dynamic and 'visual' flight environment for AACS components in the laboratory.

  6. Design evolution of the orbiter reaction control subsystem

    NASA Technical Reports Server (NTRS)

    Taeber, R. J.; Karakulko, W.; Belvins, D.; Hohmann, C.; Henderson, J.

    1985-01-01

    The challenges of space shuttle orbiter reaction control subsystem development began with selection of the propellant for the subsystem. Various concepts were evaluated before the current Earth storable, bipropellant combination was selected. Once that task was accomplished, additional challenges of designing the system to satisfy the wide range of requirements dictated by operating environments, reusability, and long life were met. Verification of system adequacy was achieved by means of a combination of analysis and test. The studies, the design efforts, and the test and analysis techniques employed in meeting the challenges are described.

  7. A prototype to automate the video subsystem routing for the video distribution subsystem of Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Betz, Jessie M. Bethly

    1993-01-01

    The Video Distribution Subsystem (VDS) for Space Station Freedom provides onboard video communications. The VDS includes three major functions: external video switching; internal video switching; and sync and control generation. The Video Subsystem Routing (VSR) is a part of the VDS Manager Computer Software Configuration Item (VSM/CSCI). The VSM/CSCI is the software which controls and monitors the VDS equipment. VSR activates, terminates, and modifies video services in response to Tier-1 commands to connect video sources to video destinations. VSR selects connection paths based on availability of resources and updates the video routing lookup tables. This project involves investigating the current methodology to automate the Video Subsystem Routing and developing and testing a prototype as 'proof of concept' for designers.

  8. Emerging Network Storage Management Standards for Intelligent Data Storage Subsystems

    NASA Technical Reports Server (NTRS)

    Podio, Fernando; Vollrath, William; Williams, Joel; Kobler, Ben; Crouse, Don

    1998-01-01

    This paper discusses the need for intelligent storage devices and subsystems that can provide data integrity metadata, the content of the existing data integrity standard for optical disks and techniques and metadata to verify stored data on optical tapes developed by the Association for Information and Image Management (AIIM) Optical Tape Committee.

  9. Double Shell Tank (DST) Diluent and Flush Subsystem Specification

    SciTech Connect

    GRAVES, C.E.

    2000-04-27

    The Double-Shell Tank (DST) Diluent and Flush Subsystem is intended to support Waste Feed Delivery. The DST Diluent and Flush Subsystem specification describes the relationship of this system with the DST System, describes the functions that must be performed by the system, and establishes the performance requirements to be applied to the design of the system. It also provides references for the requisite codes and standards. The DST Diluent and Flush Subsystem will treat the waste for a more favorable waste transfer. This will be accomplished by diluting the waste, dissolving the soluble portion of the waste, and flushing waste residuals from the transfer line. The Diluent and Flush Subsystem will consist of the following: The Diluent and Flush Station(s) where chemicals will be off-loaded, temporarily stored, mixed as necessary, heated, and metered to the delivery system; and A piping delivery system to deliver the chemicals to the appropriate valve or pump pit Associated support structures. This specification is intended to be the basis for new projects/installations. This specification is not intended to retroactively affect previously established project design criteria without specific direction by the program.

  10. Cascade Distillation Subsystem Development: Progress Toward a Distillation Comparison Test

    NASA Technical Reports Server (NTRS)

    Callahan, M. R.; Lubman, A.; Pickering, Karen D.

    2009-01-01

    Recovery of potable water from wastewater is essential for the success of long-duration manned missions to the Moon and Mars. Honeywell International and a team from NASA Johnson Space Center (JSC) are developing a wastewater processing subsystem that is based on centrifugal vacuum distillation. The wastewater processor, referred to as the Cascade Distillation Subsystem (CDS), utilizes an innovative and efficient multistage thermodynamic process to produce purified water. The rotary centrifugal design of the system also provides gas/liquid phase separation and liquid transport under microgravity conditions. A five-stage subsystem unit has been designed, built, delivered and integrated into the NASA JSC Advanced Water Recovery Systems Development Facility for performance testing. A major test objective of the project is to demonstrate the advancement of the CDS technology from the breadboard level to a subsystem level unit. An initial round of CDS performance testing was completed in fiscal year (FY) 2008. Based on FY08 testing, the system is now in development to support an Exploration Life Support (ELS) Project distillation comparison test expected to begin in early 2009. As part of the project objectives planned for FY09, the system will be reconfigured to support the ELS comparison test. The CDS will then be challenged with a series of human-gene-rated waste streams representative of those anticipated for a lunar outpost. This paper provides a description of the CDS technology, a status of the current project activities, and data on the system s performance to date.

  11. Reception-Conversion Subsystem (RXCV) for microwave power transmission system

    NASA Technical Reports Server (NTRS)

    1975-01-01

    As part of a program to demonstrate the feasibility of power transmission from space, an approximately 25 sq m Reception-Conversion Subsystem was designed and tested. The device collects high power microwave energy, converts it into dc, and dissipates it in an instrumented demonstration load.

  12. ANALYTICAL TOOL DEVELOPMENT FOR AFTERTREATMENT SUB-SYSTEMS INTEGRATION

    SciTech Connect

    Bolton, B; Fan, A; Goney, K; Pavlova-MacKinnon, Z; Sisken, K; Zhang, H

    2003-08-24

    The stringent emissions standards of 2007 and beyond require complex engine, aftertreatment and vehicle systems with a high degree of sub-system interaction and flexible control solutions. This necessitates a system-based approach to technology development, in addition to individual sub-system optimization. Analytical tools can provide an effective means to evaluate and develop such complex technology interactions as well as understand phenomena that is either too expensive or impossible to study with conventional experimental means. The analytical effort can also guide experimental development and thus lead to efficient utilization of available experimental resources.A suite of analytical models has been developed to represent PM and NOx aftertreatment sub-systems. These models range from computationally inexpensive zero-dimensional models for real-time control applications to CFD-based, multi-dimensional models with detailed temporal and spatial resolution. Such models in conjunction with well established engine modeling tools such as engine cycle simulation, engine controls modeling, CFD models of non-combusting and combusting flow, and vehicle models provide a comprehensive analytical toolbox for complete engine, aftertreatment and vehicle sub-systems development and system integration applications. However, the fidelity of aftertreatment models and application going forward is limited by the lack of fundamental kinetic data.

  13. Mark 4A DSN receiver-exciter and transmitter subsystems

    NASA Astrophysics Data System (ADS)

    Wick, M. R.

    1986-05-01

    The present configuration of the Mark 4A DSN Receiver-Exciter and Transmitter Subsystems is described. Functional requirements and key characteristics are given to show the differences in the capabilities required by the Networks Consolidation task for combined High Earth Orbiter and Deep Space Network tracking support.

  14. Mark 4A DSN receiver-exciter and transmitter subsystems

    NASA Technical Reports Server (NTRS)

    Wick, M. R.

    1986-01-01

    The present configuration of the Mark 4A DSN Receiver-Exciter and Transmitter Subsystems is described. Functional requirements and key characteristics are given to show the differences in the capabilities required by the Networks Consolidation task for combined High Earth Orbiter and Deep Space Network tracking support.

  15. Command module/service module reaction control subsystem assessment

    NASA Technical Reports Server (NTRS)

    Weary, D. P.

    1971-01-01

    Detailed review of component failure histories, qualification adequacy, manufacturing flow, checkout requirements and flow, ground support equipment interfaces, subsystem interface verification, protective devices, and component design did not reveal major weaknesses in the command service module (CSM) reaction control system (RCS). No changes to the CSM RCS were recommended. The assessment reaffirmed the adequacy of the CSM RCS for future Apollo missions.

  16. Image Processing In Laser-Beam-Steering Subsystem

    NASA Technical Reports Server (NTRS)

    Lesh, James R.; Ansari, Homayoon; Chen, Chien-Chung; Russell, Donald W.

    1996-01-01

    Conceptual design of image-processing circuitry developed for proposed tracking apparatus described in "Beam-Steering Subsystem For Laser Communication" (NPO-19069). In proposed system, desired frame rate achieved by "windowed" readout scheme in which only pixels containing and surrounding two spots read out and others skipped without being read. Image data processed rapidly and efficiently to achieve high frequency response.

  17. Apollo experience report: Lunar module display and control subsystem

    NASA Technical Reports Server (NTRS)

    Farkas, A. J.

    1972-01-01

    The lunar module display and control subsystem equipment is described with emphasis on major problems and their solutions. Included in the discussion of each item is a description of what the item does and how the item is constructed. The development, hardware history, and testing for each item are also presented.

  18. Long Duration Space Missions: Human Subsystem Risks and Requirements

    NASA Technical Reports Server (NTRS)

    Kundrot, Criag E.

    2011-01-01

    This viewgraph presentation reviews the human health and performance risks associated with long duration space flight beyond low earth orbit. The contents include: 1) Human Research Program; 2) Human Subsystem Risks; 3) Human Exploration Framework Team (HEFT) Architecture Elements; 4) Potentially Unacceptable Risks -1; 5) Potentially Unacceptable Risks-2; and 6) Major Mission Drivers of Risk.

  19. Subsystems in Nearby Solar-type Wide Binaries

    NASA Astrophysics Data System (ADS)

    Tokovinin, Andrei; Hartung, Markus; Hayward, Thomas L.

    2010-08-01

    We conducted a deep survey of resolved subsystems among wide binaries with solar-type components within 67 pc of the Sun. Images of 61 stars in the K and H bands were obtained with the Near-Infrared Coronagraphic Imager adaptive-optics instrument on the 8 m Gemini-South telescope. Our maximum detectable magnitude difference is about 5 mag and 7.8 mag at 0farcs15 and 0farcs9 separations, respectively. This enables a complete census of subsystems with stellar companions in the projected separation range from 5 to 100 AU. Out of seven such companions found in our sample, only one was previously known. We determine that the fraction of subsystems with projected separations above 5 AU is 0.12 ± 0.04 and that the distribution of their mass ratio is flat, with a power-law index of 0.2 ± 0.5. Comparing this with the properties of closer spectroscopic subsystems (separations below 1 AU), it appears that the mass-ratio distribution does not depend on the separation. The frequency of subsystems in the separation ranges below 1 AU and between 5 and 100 AU is similar, about 0.15. Unbiased statistics of multiplicity higher than 2, advanced by this work, provide constraints on star formation theory. Based on observations obtained at the Gemini Observatory (Program ID GS-2009B-Q-49), which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

  20. Development of a preprototype sabatier CO2 reduction subsystem

    NASA Technical Reports Server (NTRS)

    Kleiner, G. N.; Birbara, P.

    1980-01-01

    A preoprototype Sabatier CO2 Reduction Subsystem was successfully designed, fabricated and tested. The lightweight, quick starting reactor utilizes a highly active and physically durable methanation catalyst composed of ruthenium on alumina. The use of this improved catalyst permits a single straight through plug flow design with an average lean component H2/CO2 conversion efficiency of over 99% over a range of H2/CO2 molar ratios of 1.8 to 5 while operating with flows equivalent to a crew size of one person steadystate to 3 persons cyclical (equivalent to 5 persons steady state). The reactor requires no heater operation after start-up even during simulated 55 minute lightside/39 minute darkside orbital operation over the above range of molar ratios and crew loadings. The subsystem's operation and performance is controlled by a microprocessor and displayed on a nineteen inch multi-colored cathode ray tube.

  1. Energy Efficient Engine Low Pressure Subsystem Aerodynamic Analysis

    NASA Technical Reports Server (NTRS)

    Hall, Edward J.; Delaney, Robert A.; Lynn, Sean R.; Veres, Joseph P.

    1998-01-01

    The objective of this study was to demonstrate the capability to analyze the aerodynamic performance of the complete low pressure subsystem (LPS) of the Energy Efficient Engine (EEE). Detailed analyses were performed using three- dimensional Navier-Stokes numerical models employing advanced clustered processor computing platforms. The analysis evaluates the impact of steady aerodynamic interaction effects between the components of the LPS at design and off- design operating conditions. Mechanical coupling is provided by adjusting the rotational speed of common shaft-mounted components until a power balance is achieved. The Navier-Stokes modeling of the complete low pressure subsystem provides critical knowledge of component acro/mechanical interactions that previously were unknown to the designer until after hardware testing.

  2. SOFIA tracking subsystem: results of assembly, operation, and calibration tests

    NASA Astrophysics Data System (ADS)

    Bittner, Hermann; Erdmann, Matthias; Schmolke, Juergen; Lattner, Klaus; Levin, Torsten; Erhard, Markus

    2003-02-01

    The SOFIA airborne telescope has a Tracking Subsystem for stellar acquisition, tracking, and pointing. The system has three high-performance imagers: the boresighted wide field (6 degrees FOV) and fine field imagers (70 arcminutes FOV), and the main-telescope-optics sharing focal plane imager (8 arcminutes FOV). The imagers are controlled by 3 CCD head controllers, an overall imager controller, and a tracker controller providing the tracking error signals from the objects observed by the imagers. There have been several test steps in the assembly, integration, and verification of the Tracking Subsystem. The paper presents the fully integrated system as actually built, the results of the thermal-vacuum and vibration tests of the fine field imager, the tested operational/functional S/W performance, as well as the results of the geometric and radiometric calibrations of the imagers.

  3. OAO-3 end of mission power subsystem evaluation

    NASA Technical Reports Server (NTRS)

    Tasevoli, M.

    1982-01-01

    End of mission tests were performed on the OAO-3 power subsystem in three component areas: solar array, nickel-cadmium batteries and the On-Board Processor (OBP) power boost operation. Solar array evaluation consisted of analyzing array performance characteristics and comparing them to earlier flight data. Measured solar array degradation of 14.1 to 17.7% after 8 1/3 years is in good agreement with theortical radiation damage losses. Battery discharge characteristics were compared to results of laboratory life cycle tests performed on similar cells. Comparison of cell voltage profils reveals close correlation and confirms the validity of real time life cycle simulation. The successful operation of the system in the OBP/power boost regulation mode demonstrates the excellent life, reliability and greater system utilization of power subsystems using maximum power trackers.

  4. Automated monitor and control for deep space network subsystems

    NASA Technical Reports Server (NTRS)

    Smyth, P.

    1989-01-01

    The problem of automating monitor and control loops for Deep Space Network (DSN) subsystems is considered and an overview of currently available automation techniques is given. The use of standard numerical models, knowledge-based systems, and neural networks is considered. It is argued that none of these techniques alone possess sufficient generality to deal with the demands imposed by the DSN environment. However, it is shown that schemes that integrate the better aspects of each approach and are referenced to a formal system model show considerable promise, although such an integrated technology is not yet available for implementation. Frequent reference is made to the receiver subsystem since this work was largely motivated by experience in developing an automated monitor and control loop for the advanced receiver.

  5. Development of an advanced Sabatier CO2 reduction subsystem

    NASA Technical Reports Server (NTRS)

    Kleiner, G. N.; Cusick, R. J.

    1981-01-01

    A preprototype Sabatier CO2 reduction subsystem was successfully designed, fabricated and tested. The lightweight, quick starting (less than 5 minutes) reactor utlizes a highly active and physically durable methanation catalyst composed of ruthenium on alumina. The use of this improved catalyst permits a simple, passively controlled reactor design with an average lean component H2/CO2 conversion efficiency of over 99% over a range of H2/CO2 molar ratios of 1.8 to 5 while operating with process flows equivalent to a crew size of up to five persons. The subsystem requires no heater operation after start-up even during simulated 55 minute lightside/39 minute darkside orbital operation.

  6. Development of a preprototype Sabatier CO2 reduction subsystem

    NASA Technical Reports Server (NTRS)

    Kleiner, G. N.; Birbara, P.

    1981-01-01

    A lightweight, quick starting reactor utilizes a highly active and physically durable methanation catalyst composed of ruthenium on alumina. The use of this improved catalyst permits a single straight through plug flow design with an average lean component H2/CO2 conversion efficiency of over 99% over a range of H2/CO2 molar ratios of 1.8 to 5 while operating with flows equivalent to a crew size of one person steadystate to 3 persons cyclical. The reactor requires no heater operation after start-up even during simulated 55 minute lightside/39 minute darkside orbital operation over the above range of molar ratios and crew loadings. Subsystem performance was proven by parametric testing and endurance testing over a wide range of crew sizes and metabolic loadings. The subsystem's operation and performance is controlled by a microprocessor and displayed on a nineteen inch multi-colored cathode ray tube.

  7. Energy Efficient Engine Low Pressure Subsystem Flow Analysis

    NASA Technical Reports Server (NTRS)

    Hall, Edward J.; Lynn, Sean R.; Heidegger, Nathan J.; Delaney, Robert A.

    1998-01-01

    The objective of this project is to provide the capability to analyze the aerodynamic performance of the complete low pressure subsystem (LPS) of the Energy Efficient Engine (EEE). The analyses were performed using three-dimensional Navier-Stokes numerical models employing advanced clustered processor computing platforms. The analysis evaluates the impact of steady aerodynamic interaction effects between the components of the LPS at design and off-design operating conditions. Mechanical coupling is provided by adjusting the rotational speed of common shaft-mounted components until a power balance is achieved. The Navier-Stokes modeling of the complete low pressure subsystem provides critical knowledge of component aero/mechanical interactions that previously were unknown to the designer until after hardware testing.

  8. Pyrotechnic Actuator for Retracting Tubes Between MSL Subsystems

    NASA Technical Reports Server (NTRS)

    Gallon, John C.; Webster, Richard G.; Patterson, Keith D.; Orzewalla, Matthew A.; Roberts, Eric T.; Tuszynski, Andrew J.

    2010-01-01

    An apparatus, denoted the "retractuator" (a contraction of "retracting actuator"), was designed to help ensure clean separation between the cruise stage and the entry-vehicle subsystem of the Mars Science Laboratory (MSL) mission. The retractuator or an equivalent mechanism is needed because of tubes that (1) transport a heat-transfer fluid between the stages during flight and (2) are cut immediately prior to separation of the stages retractuator. The role of the retractuator is to retract the tubes, after they are cut and before separation of the subsystem, so that cut ends of the tubes do not damage thermal-protection coats on the entry vehicle and do not contribute to uncertainty of drag and consequent uncertainty in separation velocity.

  9. Design and Analysis of a Hyperspectral Microwave Receiver Subsystem

    NASA Technical Reports Server (NTRS)

    Blackwell, W.; Galbraith, C.; Hancock, T.; Leslie, R.; Osaretin, I.; Shields, M.; Racette, P.; Hillard, L.

    2012-01-01

    Hyperspectral microwave (HM) sounding has been proposed to achieve unprecedented performance. HM operation is achieved using multiple banks of RF spectrometers with large aggregate bandwidth. A principal challenge is Size/Weight/Power scaling. Objectives of this work: 1) Demonstrate ultra-compact (100 cm3) 52-channel IF processor (enabler); 2) Demonstrate a hyperspectral microwave receiver subsystem; and 3) Deliver a flight-ready system to validate HM sounding.

  10. Space shuttle program solid rocket booster decelerator subsystem

    NASA Technical Reports Server (NTRS)

    Barnard, J. W.

    1985-01-01

    The recovery of the Solid Rocket Boosters presented a major challenge. The SRB represents the largest payload ever recovered and presents the added complication that it is continually emitting hot gases and burning particles of insulation and other debris. Some items, such as portions of the nozzle, are large enough to burn through the nylon parachute material. The SRB Decelerator Subsystem program was highly successful in that no SRB has been lost as a result of inadequate performance of the DSS.

  11. Radioisotope thermoelectric generator transportation system subsystem 143 software development plan

    NASA Astrophysics Data System (ADS)

    King, D. A.

    1994-11-01

    This plan describes the activities to be performed and the controls to be applied to the process of specifying, developing, and qualifying the data acquisition software for the Radioisotope Thermoelectric Generator (RTG) Transportation System Subsystem 143 Instrumentation and Data Acquisition System (IDAS). This plan will serve as a software quality assurance plan, a verification and validation (V and V) plan, and a configuration management plan.

  12. Radioisotope thermoelectric generator transportation system subsystem 143 software development plan

    SciTech Connect

    King, D.A.

    1994-11-10

    This plan describes the activities to be performed and the controls to be applied to the process of specifying, developing, and qualifying the data acquisition software for the Radioisotope Thermoelectric Generator (RTG) Transportation System Subsystem 143 Instrumentation and Data Acquisition System (IDAS). This plan will serve as a software quality assurance plan, a verification and validation (V and V) plan, and a configuration management plan.

  13. TRIGA: Telecommunications Protocol Processing Subsystem Using Reconfigurable Interoperable Gate Arrays

    NASA Technical Reports Server (NTRS)

    Pang, Jackson; Pingree, Paula J.; Torgerson, J. Leigh

    2006-01-01

    We present the Telecommunications protocol processing subsystem using Reconfigurable Interoperable Gate Arrays (TRIGA), a novel approach that unifies fault tolerance, error correction coding and interplanetary communication protocol off-loading to implement CCSDS File Delivery Protocol and Datalink layers. The new reconfigurable architecture offers more than one order of magnitude throughput increase while reducing footprint requirements in memory, command and data handling processor utilization, communication system interconnects and power consumption.

  14. Attitude Control Subsystem for the Advanced Communications Technology Satellite

    NASA Technical Reports Server (NTRS)

    Hewston, Alan W.; Mitchell, Kent A.; Sawicki, Jerzy T.

    1996-01-01

    This paper provides an overview of the on-orbit operation of the Attitude Control Subsystem (ACS) for the Advanced Communications Technology Satellite (ACTS). The three ACTS control axes are defined, including the means for sensing attitude and determining the pointing errors. The desired pointing requirements for various modes of control as well as the disturbance torques that oppose the control are identified. Finally, the hardware actuators and control loops utilized to reduce the attitude error are described.

  15. Photovoltaic subsystem optimization and design tradeoff study. Final report

    SciTech Connect

    Stolte, W.J.

    1982-03-01

    Tradeoffs and subsystem choices are examined in photovoltaic array subfield design, power-conditioning sizing and selection, roof- and ground-mounted structure installation, energy loss, operating voltage, power conditioning cost, and subfield size. Line- and self-commutated power conditioning options are analyzed to determine the most cost-effective technology in the megawatt power range. Methods for reducing field installation of flat panels and roof mounting of intermediate load centers are discussed, including the cost of retrofit installations.

  16. Development of Testing Station for Prototype Rover Thermal Subsystem

    NASA Technical Reports Server (NTRS)

    Burlingame, Kaitlin

    2010-01-01

    In order to successfully and efficiently explore the moon or other planets, a vehicle must be built to assist astronauts as they travel across the surface. One concept created to meet this need is NASA's Space Exploration Vehicle (SEV). The SEV, a small pressurized cabin integrated onto a 12-wheeled chassis, can support two astronauts up to 14 days. Engineers are currently developing the second generation of the SEV, with the goal of being faster, more robust, and able to carry a heavier payload. In order to function properly, the rover must dissipate heat produced during operation and maintain an appropriate temperature profile inside the rover. If these activities do not occur, components of the rover will start to break down, eventually leading to the failure of the rover. On the rover, these requirements are the responsibility of the thermal subsystem. My project for the summer was to design and build a testing station to facilitate the design and testing of the new thermal subsystem. As the rover develops, initial low fidelity parts can be interchanged for the high fidelity parts used on the rover. Based on a schematic of the proposed thermal system, I sized and selected parts for each of the components in the thermal subsystem. For the components in the system that produced heat but had not yet been finalized or fabricated, I used power resistors to model their load patterns. I also selected all of the fittings to put the system together and a mounting platform to support the testing station. Finally, I implemented sensors at various points in the system to measure the temperature, pressure, and flow rate, and a data acquisition system to collect this information. In the future, the information from these sensors will be used to study the behavior of the subsystem under different conditions and select the best part for the rover.

  17. Evolution of the 1-mlb mercury ion thruster subsystem

    NASA Technical Reports Server (NTRS)

    Kerslake, W. R.; Banks, B. A.

    1978-01-01

    The developmental history, performance, and major lifetests of each component of the present 1-mlb (4.5 mN) thruster system are traced over the past 10 years. The 1-mlb thruster subsystem consists of an 8 cm diameter ion thruster mounted on 2 axis gimbals, a mercury propellant tank, a power electronics unit, a controller/digital interface unit, and necessary electrical harnesses plus propellant tankage and feed lines.

  18. Earth-to-orbit propulsion turbomachinery subsystem: Overview

    NASA Technical Reports Server (NTRS)

    Schutzenhofer, L. A.; Garcia, R.

    1991-01-01

    The topics presented are covered in viewgraph form. The objectives are: (1) to develop the technology related to the turbomachinery systems of high performance rocket engines, which focuses on advanced design methodologies and concepts, develops high performance turbomachinery data bases, and validates turbomachinery design tools; and (2) specific turbomachinery subsystems and disciplines, which focus on turbine stages, pump stages, bearings, deals, structural dynamics, complex flow paths, materials, manufacturability, producibility, and inspectability, rotordynamics, and fatigue/fracture/life.

  19. Thermal performance evaluation of the infrared telescope dewar subsystem

    NASA Technical Reports Server (NTRS)

    Urban, E. W.

    1986-01-01

    Thermal performance evaluations (TPE) were conducted with the superfluid helium dewar of the Infrared Telescope (IRT) experiment from November 1981 to August 1982. Test included measuring key operating parameters, simulating operations with an attached instrument cryostat and validating servicing, operating and safety procedures. Test activities and results are summarized. All objectives are satisfied except for those involving transfer of low pressure liquid helium (LHe) from a supply dewar into the dewar subsystem.

  20. Subsystem real-time time dependent density functional theory.

    PubMed

    Krishtal, Alisa; Ceresoli, Davide; Pavanello, Michele

    2015-04-21

    We present the extension of Frozen Density Embedding (FDE) formulation of subsystem Density Functional Theory (DFT) to real-time Time Dependent Density Functional Theory (rt-TDDFT). FDE is a DFT-in-DFT embedding method that allows to partition a larger Kohn-Sham system into a set of smaller, coupled Kohn-Sham systems. Additional to the computational advantage, FDE provides physical insight into the properties of embedded systems and the coupling interactions between them. The extension to rt-TDDFT is done straightforwardly by evolving the Kohn-Sham subsystems in time simultaneously, while updating the embedding potential between the systems at every time step. Two main applications are presented: the explicit excitation energy transfer in real time between subsystems is demonstrated for the case of the Na4 cluster and the effect of the embedding on optical spectra of coupled chromophores. In particular, the importance of including the full dynamic response in the embedding potential is demonstrated. PMID:25903875

  1. Double Shell Tank (DST) Transfer Valving Subsystem Specification

    SciTech Connect

    GRAVES, C.E.

    2000-03-22

    This specification establishes the performance requirements and provides references to the requisite codes and standards to be applied during design of the Double-Shell Tank (DST) Transfer Valving Subsystem that supports the first phase of Waste Feed Delivery. This specification establishes the performance requirements and provides references to the requisite codes and standards to be applied during design of the Double-Shell Tank (DST) Transfer Valving Subsystem that supports the first phase of Waste Feed Delivery (WFD). The DST Transfer Valving Subsystem routes waste and other media (e.g., diluent, flush water, filtered raw water) among DSTs and from the low-activity waste (LAW) and high-level waste (HLW) feed staging tanks to the River Protection Project (RPP) Privatization Contractor facility, where it will be processed into an immobilized waste form. This specification is intended to be the basis for new projects/installations (W-521, etc.). This specification is not intended to retroactively affect previously established project design criteria without specific direction by the program.

  2. Static Feed Water Electrolysis Subsystem Testing and Component Development

    NASA Technical Reports Server (NTRS)

    Koszenski, E. P.; Schubert, F. H.; Burke, K. A.

    1983-01-01

    A program was carried out to develop and test advanced electrochemical cells/modules and critical electromechanical components for a static feed (alkaline electrolyte) water electrolysis oxygen generation subsystem. The accomplishments were refurbishment of a previously developed subsystem and successful demonstration for a total of 2980 hours of normal operation; achievement of sustained one-person level oxygen generation performance with state-of-the-art cell voltages averaging 1.61 V at 191 ASF for an operating temperature of 128F (equivalent to 1.51V when normalized to 180F); endurance testing and demonstration of reliable performance of the three-fluid pressure controller for 8650 hours; design and development of a fluid control assembly for this subsystem and demonstration of its performance; development and demonstration at the single cell and module levels of a unitized core composite cell that provides expanded differential pressure tolerance capability; fabrication and evaluation of a feed water electrolyte elimination five-cell module; and successful demonstration of an electrolysis module pressurization technique that can be used in place of nitrogen gas during the standby mode of operation to maintain system pressure and differential pressures.

  3. Laser and Optical Subsystem for NASA's Cold Atom Laboratory

    NASA Astrophysics Data System (ADS)

    Kohel, James; Kellogg, James; Elliott, Ethan; Krutzik, Markus; Aveline, David; Thompson, Robert

    2016-05-01

    We describe the design and validation of the laser and optics subsystem for NASA's Cold Atom Laboratory (CAL), a multi-user facility being developed at NASA's Jet Propulsion Laboratory for studies of ultra-cold quantum gases in the microgravity environment of the International Space Station. Ultra-cold atoms will be generated in CAL by employing a combination of laser cooling techniques and evaporative cooling in a microchip-based magnetic trap. Laser cooling and absorption imaging detection of bosonic mixtures of 87 Rb and 39 K or 41 K will be accomplished using a high-power (up to 500 mW ex-fiber), frequency-agile dual wavelength (767 nm and 780 nm) laser and optical subsystem. The CAL laser and optical subsystem also includes the capability to generate high-power multi-frequency optical pulses at 784.87 nm to realize a dual-species Bragg atom interferometer. Currently at Humboldt-Universität zu Berlin.

  4. Space Shuttle Orbiter audio subsystem. [to communication and tracking system

    NASA Technical Reports Server (NTRS)

    Stewart, C. H.

    1978-01-01

    The selection of the audio multiplex control configuration for the Space Shuttle Orbiter audio subsystem is discussed and special attention is given to the evaluation criteria of cost, weight and complexity. The specifications and design of the subsystem are described and detail is given to configurations of the audio terminal and audio central control unit (ATU, ACCU). The audio input from the ACCU, at a signal level of -12.2 to 14.8 dBV, nominal range, at 1 kHz, was found to have balanced source impedance and a balanced local impedance of 6000 + or - 600 ohms at 1 kHz, dc isolated. The Lyndon B. Johnson Space Center (JSC) electroacoustic test laboratory, an audio engineering facility consisting of a collection of acoustic test chambers, analyzed problems of speaker and headset performance, multiplexed control data coupled with audio channels, and the Orbiter cabin acoustic effects on the operational performance of voice communications. This system allows technical management and project engineering to address key constraining issues, such as identifying design deficiencies of the headset interface unit and the assessment of the Orbiter cabin performance of voice communications, which affect the subsystem development.

  5. System integration of marketable subsystems. [for residential solar heating and cooling

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Progress is reported in the following areas: systems integration of marketable subsystems; development, design, and building of site data acquisition subsystems; development and operation of the central data processing system; operation of the MSFC Solar Test Facility; and systems analysis.

  6. Recommendations of OSTA Flight Technology Improvement Workshop-Power Subsystems panel

    NASA Technical Reports Server (NTRS)

    Slifer, L. W., Jr.

    1980-01-01

    The recommendations of the power subsystems panel are discussed; The thrust is directed at radiometric problems. Areas that need development are defined for both spacecraft power subsystems and power supplies for experiments and instruments.

  7. National Ingition Facility subsystem design requirements optical mounts SSDR 1.4.4

    SciTech Connect

    Richardson, M.

    1996-10-06

    This SSDR establishes the performance, design, development and test requirements for NIF Beam Transport Optomechanical Subsystems. optomechanical Subsystems includes the mounts for the beam transport mirrors, LMl - LM8, the polarizer mount, and the spatial filter lens mounts.

  8. On DESTINY Science Instrument Electrical and Electronics Subsystem Framework

    NASA Technical Reports Server (NTRS)

    Kizhner, Semion; Benford, Dominic J.; Lauer, Tod R.

    2009-01-01

    Future space missions are going to require large focal planes with many sensing arrays and hundreds of millions of pixels all read out at high data rates'' . This will place unique demands on the electrical and electronics (EE) subsystem design and it will be critically important to have high technology readiness level (TRL) EE concepts ready to support such missions. One such omission is the Joint Dark Energy Mission (JDEM) charged with making precise measurements of the expansion rate of the universe to reveal vital clues about the nature of dark energy - a hypothetical form of energy that permeates all of space and tends to increase the rate of the expansion. One of three JDEM concept studies - the Dark Energy Space Telescope (DESTINY) was conducted in 2008 at the NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Maryland. This paper presents the EE subsystem framework, which evolved from the DESTINY science instrument study. It describes the main challenges and implementation concepts related to the design of an EE subsystem featuring multiple focal planes populated with dozens of large arrays and millions of pixels. The focal planes are passively cooled to cryogenic temperatures (below 140 K). The sensor mosaic is controlled by a large number of Readout Integrated Circuits and Application Specific Integrated Circuits - the ROICs/ASICs in near proximity to their sensor focal planes. The ASICs, in turn, are serviced by a set of "warm" EE subsystem boxes performing Field Programmable Gate Array (FPGA) based digital signal processing (DSP) computations of complex algorithms, such as sampling-up-the-ramp algorithm (SUTR), over large volumes of fast data streams. The SUTR boxes are supported by the Instrument Control/Command and Data Handling box (ICDH Primary and Backup boxes) for lossless data compression, command and low volume telemetry handling, power conversion and for communications with the spacecraft. The paper outlines how the JDEM DESTINY concept

  9. Predicting Speech Intelligibility with a Multiple Speech Subsystems Approach in Children with Cerebral Palsy

    ERIC Educational Resources Information Center

    Lee, Jimin; Hustad, Katherine C.; Weismer, Gary

    2014-01-01

    Purpose: Speech acoustic characteristics of children with cerebral palsy (CP) were examined with a multiple speech subsystems approach; speech intelligibility was evaluated using a prediction model in which acoustic measures were selected to represent three speech subsystems. Method: Nine acoustic variables reflecting different subsystems, and…

  10. Combining and connecting linear, multi-input, multi-output subsystem models

    NASA Technical Reports Server (NTRS)

    Duke, E. L.

    1986-01-01

    The mathematical background for combining and connecting linear, multi-input, multi-output subsystem models into an overall system model is provided. Several examples of subsystem configurations are examined in detail. A description of a MATRIX (sub x) command file to aid in the process of combining and connecting these subsystem models is contained.

  11. Systems and methods for an integrated electrical sub-system powered by wind energy

    DOEpatents

    Liu, Yan; Garces, Luis Jose

    2008-06-24

    Various embodiments relate to systems and methods related to an integrated electrically-powered sub-system and wind power system including a wind power source, an electrically-powered sub-system coupled to and at least partially powered by the wind power source, the electrically-powered sub-system being coupled to the wind power source through power converters, and a supervisory controller coupled to the wind power source and the electrically-powered sub-system to monitor and manage the integrated electrically-powered sub-system and wind power system.

  12. Autonomous navigation - The ARMMS concept. [Autonomous Redundancy and Maintenance Management Subsystem

    NASA Technical Reports Server (NTRS)

    Wood, L. J.; Jones, J. B.; Mease, K. D.; Kwok, J. H.; Goltz, G. L.; Kechichian, J. A.

    1984-01-01

    A conceptual design is outlined for the navigation subsystem of the Autonomous Redundancy and Maintenance Management Subsystem (ARMMS). The principal function of this navigation subsystem is to maintain the spacecraft over a specified equatorial longitude to within + or - 3 deg. In addition, the navigation subsystem must detect and correct internal faults. It comprises elements for a navigation executive and for orbit determination, trajectory, maneuver planning, and maneuver command. Each of these elements is described. The navigation subsystem is to be used in the DSCS III spacecraft.

  13. RF communications subsystem for the Radiation Belt Storm Probes mission

    NASA Astrophysics Data System (ADS)

    Srinivasan, Dipak K.; Artis, David; Baker, Ben; Stilwell, Robert; Wallis, Robert

    2009-12-01

    The NASA Radiation Belt Storm Probes (RBSP) mission, currently in Phase B, is a two-spacecraft, Earth-orbiting mission, which will launch in 2012. The spacecraft's S-band radio frequency (RF) telecommunications subsystem has three primary functions: provide spacecraft command capability, provide spacecraft telemetry and science data return, and provide accurate Doppler data for navigation. The primary communications link to the ground is via the Johns Hopkins University Applied Physics Laboratory's (JHU/APL) 18 m dish, with secondary links to the NASA 13 m Ground Network and the Tracking and Data Relay Spacecraft System (TDRSS) in single-access mode. The on-board RF subsystem features the APL-built coherent transceiver and in-house builds of a solid-state power amplifier and conical bifilar helix broad-beam antennas. The coherent transceiver provides coherency digitally, and controls the downlink data rate and encoding within its field-programmable gate array (FPGA). The transceiver also provides a critical command decoder (CCD) function, which is used to protect against box-level upsets in the C&DH subsystem. Because RBSP is a spin-stabilized mission, the antennas must be symmetric about the spin axis. Two broad-beam antennas point along both ends of the spin axis, providing communication coverage from boresight to 70°. An RF splitter excites both antennas; therefore, the mission is designed such that no communications are required close to 90° from the spin axis due to the interferometer effect from the two antennas. To maximize the total downlink volume from the spacecraft, the CCSDS File Delivery Protocol (CFDP) has been baselined for the RBSP mission. During real-time ground contacts with the APL ground station, downlinked files are checked for errors. Handshaking between flight and ground CFDP software results in requests to retransmit only the file fragments lost due to dropouts. This allows minimization of RF link margins, thereby maximizing data rate and

  14. Flow Analysis of a Gas Turbine Low- Pressure Subsystem

    NASA Technical Reports Server (NTRS)

    Veres, Joseph P.

    1997-01-01

    The NASA Lewis Research Center is coordinating a project to numerically simulate aerodynamic flow in the complete low-pressure subsystem (LPS) of a gas turbine engine. The numerical model solves the three-dimensional Navier-Stokes flow equations through all components within the low-pressure subsystem as well as the external flow around the engine nacelle. The Advanced Ducted Propfan Analysis Code (ADPAC), which is being developed jointly by Allison Engine Company and NASA, is the Navier-Stokes flow code being used for LPS simulation. The majority of the LPS project is being done under a NASA Lewis contract with Allison. Other contributors to the project are NYMA and the University of Toledo. For this project, the Energy Efficient Engine designed by GE Aircraft Engines is being modeled. This engine includes a low-pressure system and a high-pressure system. An inlet, a fan, a booster stage, a bypass duct, a lobed mixer, a low-pressure turbine, and a jet nozzle comprise the low-pressure subsystem within this engine. The tightly coupled flow analysis evaluates aerodynamic interactions between all components of the LPS. The high-pressure core engine of this engine is simulated with a one-dimensional thermodynamic cycle code in order to provide boundary conditions to the detailed LPS model. This core engine consists of a high-pressure compressor, a combustor, and a high-pressure turbine. The three-dimensional LPS flow model is coupled to the one-dimensional core engine model to provide a "hybrid" flow model of the complete gas turbine Energy Efficient Engine. The resulting hybrid engine model evaluates the detailed interaction between the LPS components at design and off-design engine operating conditions while considering the lumped-parameter performance of the core engine.

  15. Characterization of Subsystems for a WB-003 Single Stage Shuttle

    NASA Technical Reports Server (NTRS)

    MacConochie, Ian O.; Lepsch, Roger A., Jr. (Technical Monitor)

    2002-01-01

    Subsystems for an all oxygen-hydrogen-single-stage shuttle are characterized for a vehicle designated WB-003. Features of the vehicle include all-electric actuation, fiber optics for information circuitry, fuel cells for power generation, and extensive use of composites for structure. The vehicle is sized for the delivery of a 25,000 lb. payload to a space station orbit without crew. When crew are being delivered, they are carried in a module in the payload bay with escape and manual override capabilities. The underlying reason for undertaking this task is to provide a framework for the study of the operations costs of the newer shuttles.

  16. An inverter/controller subsystem optimized for photovoltaic applications

    NASA Technical Reports Server (NTRS)

    Pickrell, R. L.; Osullivan, G.; Merrill, W. C.

    1978-01-01

    Conversion of solar array dc power to ac power stimulated the specification, design, and simulation testing of an inverter/controller subsystem tailored to the photovoltaic power source characteristics. Optimization of the inverter/controller design is discussed as part of an overall photovoltaic power system designed for maximum energy extraction from the solar array. The special design requirements for the inverter/ controller include: a power system controller (PSC) to control continuously the solar array operating point at the maximum power level based on variable solar insolation and cell temperatures; and an inverter designed for high efficiency at rated load and low losses at light loadings to conserve energy.

  17. Reactor Subsystem Simulation for Nuclear Hybrid Energy Systems

    SciTech Connect

    Shannon Bragg-Sitton; J. Michael Doster; Alan Rominger

    2012-09-01

    Preliminary system models have been developed by Idaho National Laboratory researchers and are currently being enhanced to assess integrated system performance given multiple sources (e.g., nuclear + wind) and multiple applications (i.e., electricity + process heat). Initial efforts to integrate a Fortran-based simulation of a small modular reactor (SMR) with the balance of plant model have been completed in FY12. This initial effort takes advantage of an existing SMR model developed at North Carolina State University to provide initial integrated system simulation for a relatively low cost. The SMR subsystem simulation details are discussed in this report.

  18. Inflight performance of the Viking visual imaging subsystem

    NASA Technical Reports Server (NTRS)

    Klaasen, K. P.; Thorpe, T. E.; Morabito, L. A.

    1977-01-01

    Photography from the Viking Orbiter Visual Imaging Subsystem, taken while enroute to and in orbit about Mars, has been analyzed to determine the performance of the cameras. The cameras have remained in good focus. Random and coherent noise levels in flight were the same as measured prior to launch. A recalibration of each instrument allows photometric measurements to accuracies of less than 3% for relative measurements and 9% for absolute measurements. Geometric distortion remained close to the preflight levels of 4 pixels rms and 11 pixels maximum.

  19. Electric and hybrid vehicles environmental control subsystem study

    NASA Technical Reports Server (NTRS)

    1981-01-01

    An environmental control subsystem (ECS) in the passenger compartment of electric and hybrid vehicles is studied. Various methods of obtaining the desired temperature control for the battery pack is also studied. The functional requirements of ECS equipment is defined. Following categorization by methodology, technology availability and risk, all viable ECS concepts are evaluated. Each is assessed independently for benefits versus risk, as well as for its feasibility to short, intermediate and long term product development. Selection of the preferred concept is made against these requirements, as well as the study's major goal of providing safe, highly efficient and thermally confortable ECS equipment.

  20. Electric and hybrid vehicle environmental control subsystem study

    NASA Technical Reports Server (NTRS)

    Heitner, K. L.

    1980-01-01

    An environmental control subsystem (ECS) in electric and hybrid vehicles is studied. A combination of a combustion heater and gasoline engine (Otto cycle) driven vapor compression air conditioner is selected. The combustion heater, the small gasoline engine, and the vapor compression air conditioner are commercially available. These technologies have good cost and performance characteristics. The cost for this ECS is relatively close to the cost of current ECS's. Its effect on the vehicle's propulsion battery is minimal and the ECS size and weight do not have significant impact on the vehicle's range.

  1. Revalidation of the Huygens Descent Control Sub-System

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The Huygens probe, part of the Cassini mission to Saturn, is designed to investigate the atmosphere of Titan, Saturn's largest moon. The passage of the probe through the atmosphere is controlled by the Descent Control Sub-System (DCSS), which consists of three parachutes and associated mechanisms. The Cassini / Huygens mission was launched in October 1997 and was designed during the early 1990's. During the time since the design and launch, analysis capabilities have improved significantly, knowledge of the Titan environment has improved and the baseline mission has been modified. Consequently, a study was performed to revalidate the DCSS design against the current predictions.

  2. Addendum: Development of a preprototype times wastewater recovery subsystem

    NASA Technical Reports Server (NTRS)

    Dehner, G. F.

    1984-01-01

    The results of the second generation operational improvements and the TIMES (Thermoelectric Integrated Membrane Evaporation Subsystem) 2 study are covered. Areas covered in the second generation operational improvements are improved temperature control, water quality improvements, subsytem operational improvements, solid handling improvements, wastewater pretreatment optimization, and membrane rejuvenation concepts. The task for the TIMES 2 study are thermoelectric regenerator improvement, recycle loop pH operational criteria, recycle loop component optimization, and hollow fiber membrane evaporator improvement. Results are presented and conclusions are drawn from both studies.

  3. Use of STS subsystems and components for MMSE, volume 1

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Multiuse mission support equipment (MMSE) is flight/ground equipment for the shuttle era which is used in conjunction with more than one mission payload. Initial verification of STS subsystem's applicability to MMSE is provided along with the cost savings potential and programmatic data needed for further program planning decisions. Some 70 MMSE requirements were found to be potentially satisfied by STS equipment, and and 6 items of particular interest were chosen for special emphasis. All were found to be feasible and beneficial. Program cost savings through their use are estimated to be substantial. Further study is recommended to identify additional MMSE requirements and hardware.

  4. A shuttle radar microwave subsystem for earth resources applications

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Microwave subsystem considerations are discussed as a design example for a radar for earth resources applications to be used in conjunction with the shuttle spacelab. This system with a multiplicity of frequencies and polarizations - L-band (25-cm wavelength), S-band (10-cm wavelength), and X-band (3.2-cm wavelength) at two orthogonal linear polarizations - was tentatively selected. The space shuttle vehicle constrains the antenna to approximately 8 m in length and 3 m in width. The frequencies and antenna size comprise the major constraints on the system described, and determine the sensor altitude, coverage, and major hardware parameters.

  5. Automation study for space station subsystems and mission ground support

    NASA Technical Reports Server (NTRS)

    1985-01-01

    An automation concept for the autonomous operation of space station subsystems, i.e., electric power, thermal control, and communications and tracking are discussed. To assure that functions essential for autonomous operations are not neglected, an operations function (systems monitoring and control) is included in the discussion. It is recommended that automated speech recognition and synthesis be considered a basic mode of man/machine interaction for space station command and control, and that the data management system (DMS) and other systems on the space station be designed to accommodate fully automated fault detection, isolation, and recovery within the system monitoring function of the DMS.

  6. The sensing and perception subsystem of the NASA research telerobot

    NASA Technical Reports Server (NTRS)

    Wilcox, B.; Gennery, D. B.; Bon, B.; Litwin, T.

    1987-01-01

    A useful space telerobot for on-orbit assembly, maintenance, and repair tasks must have a sensing and perception subsystem which can provide the locations, orientations, and velocities of all relevant objects in the work environment. This function must be accomplished with sufficient speed and accuracy to permit effective grappling and manipulation. Appropriate symbolic names must be attached to each object for use by higher-level planning algorithms. Sensor data and inferences must be presented to the remote human operator in a way that is both comprehensible in ensuring safe autonomous operation and useful for direct teleoperation. Research at JPL toward these objectives is described.

  7. Space Shuttle reaction control subsystem propellant tank masked screen test

    NASA Technical Reports Server (NTRS)

    Henderson, J. B.

    1984-01-01

    During final development testing of the Space Shuttle Reaction Control Subsystem propellant tanks, a problem with pressure transients in the system was uncovered. Due to the nature of the tanks, performance tests to determine the impact of the transients on the expulsion efficiency of the tanks could not directly simulate the actual conditions which would be present in a low-gravity environment. However, by masking or covering various segments of the propellant acquisition device, a good simulation of a low-gravity environment was achieved in ground testing.

  8. A cost effective data management subsystem for the LST

    NASA Technical Reports Server (NTRS)

    Dougherty, J. A.; Patterson, T. D.; Cole, A. E.

    1975-01-01

    The paper outlines the approach used in developing DMS (Data Management Subsystem) alternatives for the LST (Large Space Telescope) and in selecting the concept considered to be the most cost effective means of implementing the LST DMS requirements. Two candidate DMS concepts are discussed: a functionally integrated and a functionally separated one. For the single vehicle LST program, separation of the DMS functions best provides high reliability, operations flexibility, minimal interface complexity, and the least complex software development and verification task. The use of available hardware and NASA standard components is stressed.

  9. Data Management Applications for the Service Preparation Subsystem

    NASA Technical Reports Server (NTRS)

    Luong, Ivy P.; Chang, George W.; Bui, Tung; Allen, Christopher; Malhotra, Shantanu; Chen, Fannie C.; Bui, Bach X.; Gutheinz, Sandy C.; Kim, Rachel Y.; Zendejas, Silvino C.; Yu, Dan; Kim, Richard M.; Sadaqathulla, Syed

    2009-01-01

    These software applications provide intuitive User Interfaces (UIs) with a consistent look and feel for interaction with, and control of, the Service Preparation Subsystem (SPS). The elements of the UIs described here are the File Manager, Mission Manager, and Log Monitor applications. All UIs provide access to add/delete/update data entities in a complex database schema without requiring technical expertise on the part of the end users. These applications allow for safe, validated, catalogued input of data. Also, the software has been designed in multiple, coherent layers to promote ease of code maintenance and reuse in addition to reducing testing and accelerating maturity.

  10. Revealing electronic open quantum systems with subsystem TDDFT.

    PubMed

    Krishtal, Alisa; Pavanello, Michele

    2016-03-28

    Open quantum systems (OQSs) are perhaps the most realistic systems one can approach through simulations. In recent years, describing OQSs with Density Functional Theory (DFT) has been a prominent avenue of research with most approaches based on a density matrix partitioning in conjunction with an ad-hoc description of system-bath interactions. We propose a different theoretical approach to OQSs based on partitioning of the electron density. Employing the machinery of subsystem DFT (and its time-dependent extension), we provide a novel way of isolating and analyzing the various terms contributing to the coupling between the system and the surrounding bath. To illustrate the theory, we provide numerical simulations on a toy system (a molecular dimer) and on a condensed phase system (solvated excimer). The simulations show that non-Markovian dynamics in the electronic system-bath interactions are important in chemical applications. For instance, we show that the superexchange mechanism of transport in donor-bridge-acceptor systems is a non-Markovian interaction between the donor-acceptor (OQS) with the bridge (bath) which is fully characterized by real-time subsystem time-dependent DFT. PMID:27036438

  11. Spectral characterization of the LANDSAT-D multispectral scanner subsystems

    NASA Technical Reports Server (NTRS)

    Markham, B. L. (Principal Investigator); Barker, J. L.

    1982-01-01

    Relative spectral response data for the multispectral scanner subsystems (MSS) to be flown on LANDSAT-D and LANDSAT-D backup, the protoflight and flight models, respectively, are presented and compared to similar data for the Landsat 1,2, and 3 subsystems. Channel-bychannel (six channels per band) outputs for soil and soybean targets were simulated and compared within each band and between scanners. The two LANDSAT-D scanners proved to be nearly identical in mean spectral response, but they exhibited some differences from the previous MSS's. Principal differences between the spectral responses of the D-scanners and previous scanners were: (1) a mean upper-band edge in the green band of 606 nm compared to previous means of 593 to 598 nm; (2) an average upper-band edge of 697 nm in the red band compared to previous averages of 701 to 710 nm; and (3) an average bandpass for the first near-IR band of 702-814 nm compared to a range of 693-793 to 697-802 nm for previous scanners. These differences caused the simulated D-scanner outputs to be 3 to 10 percent lower in the red band and 3 to 11 percent higher in the first near-IR band than previous scanners for the soybeans target. Otherwise, outputs from soil and soybean targets were only slightly affected. The D-scanners were generally more uniform from channel to channel within bands than previous scanners.

  12. Independent Orbiter Assessment (IOA): Analysis of the instrumentation subsystem

    NASA Technical Reports Server (NTRS)

    Howard, B. S.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Instrumentation Subsystem are documented. The Instrumentation Subsystem (SS) consists of transducers, signal conditioning equipment, pulse code modulation (PCM) encoding equipment, tape recorders, frequency division multiplexers, and timing equipment. For this analysis, the SS is broken into two major groupings: Operational Instrumentation (OI) equipment and Modular Auxiliary Data System (MADS) equipment. The OI equipment is required to acquire, condition, scale, digitize, interleave/multiplex, format, and distribute operational Orbiter and payload data and voice for display, recording, telemetry, and checkout. It also must provide accurate timing for time critical functions for crew and payload specialist use. The MADS provides additional instrumentation to measure and record selected pressure, temperature, strain, vibration, and event data for post-flight playback and analysis. MADS data is used to assess vehicle responses to the flight environment and to permit correlation of such data from flight to flight. The IOA analysis utilized available SS hardware drawings and schematics for identifying hardware assemblies and components and their interfaces. Criticality for each item was assigned on the basis of the worst-case effect of the failure modes identified.

  13. Orbits of Subsystems in Four Hierarchical Multiple Stars

    NASA Astrophysics Data System (ADS)

    Tokovinin, Andrei

    2016-07-01

    Seven spectroscopic orbits in nearby solar-type multiple stars are presented. The primary of the chromospherically active star HIP 9642 is a 4.8 day double-lined pair; the outer 420 year visual orbit is updated, but remains poorly constrained. HIP 12780 is a quadruple system consisting of the resolved 6.7 year pair FIN 379 Aa,Ab, for which the combined orbit, masses, and orbital parallax are determined here, and the single-lined binary Ba,Bb with a period of 27.8 days. HIP 28790 is a young quintuple system composed of two close binaries, Aa,Ab and Ba,Bb, with periods of 221 and 13 days, respectively, and a single distant component C. Its subsystem Ba,Bb is peculiar, having a spectroscopic mass ratio of 0.89 but a magnitude difference of ˜2.2 mag. HIP 64478 also contains five stars: the A-component is a 29 year visual pair with a previously known 4 day twin subsystem, while the B-component is a contact binary with a period of 5.8 hr, seen nearly pole-on.

  14. Optimisation study of a vehicle bumper subsystem with fuzzy parameters

    NASA Astrophysics Data System (ADS)

    Farkas, L.; Moens, D.; Donders, S.; Vandepitte, D.

    2012-10-01

    This paper deals with the design and optimisation for crashworthiness of a vehicle bumper subsystem, which is a key scenario for vehicle component design. The automotive manufacturers and suppliers have to find optimal design solutions for such subsystems that comply with the conflicting requirements of the regulatory bodies regarding functional performance (safety and repairability) and regarding the environmental impact (mass). For the bumper design challenge, an integrated methodology for multi-attribute design engineering of mechanical structures is set up. The integrated process captures the various tasks that are usually performed manually, this way facilitating the automated design iterations for optimisation. Subsequently, an optimisation process is applied that takes the effect of parametric uncertainties into account, such that the system level of failure possibility is acceptable. This optimisation process is referred to as possibility-based design optimisation and integrates the fuzzy FE analysis applied for the uncertainty treatment in crash simulations. This process is the counterpart of the reliability-based design optimisation used in a probabilistic context with statistically defined parameters (variabilities).

  15. Satellite Power System (SPS) microwave subsystem impacts and benefits

    NASA Technical Reports Server (NTRS)

    Dickinson, R. M.

    1977-01-01

    The impacts and benefits to society of the microwave subsystem resulting from the developing, construction and operating of a space solar power to earth, electric power delivery system are presented and discussed. The primary benefit (usable energy) is conveyed mainly in the fundamental frequency portion of the RF radiation beam that is intercepted and converted to electric power output. The small fraction of the microwave and other electromagnetic energy that does not end up in the electric utility grid, yields most of the subsystem impacts. The impacts range from harmonics and noise radiated by the transmitting antenna, through potential interference with ionospheric communications and navigation caused by the power beam heating the ionosphere, to the potential large land area requirements for the rectennas and low level microwave radiation around the rectennas. Additional benefits range from a very low level of waste heat liberated and lack of atmospheric emissions including noise while operating to having no residual ionizing radiation from the rectenna when it is deactivated.

  16. Extraction of climate subsystems on the basis of MSSA technique

    NASA Astrophysics Data System (ADS)

    Loskutov, Evgeny; Mukhin, Dmitry; Gavrilov, Andrey; Feigin, Alexander

    2015-04-01

    It is well known that empirical modeling of Earth's climate system is ambitious, but very difficult task by virtue of system's complexity and spatial distribution of data. One of the ways to reduce data complexity is distinguishing a set of principal spatio-temporal patterns that evolve with essentially different time scales. In the report we discuss the new method for construction such patterns which allows to extract leading climate subsystems underlying the observed variability. The first stage of method is based on MSSA (Multichannel Singular Spectral Analysis) which is used for expanding space-distributed time series into the basis of spatio-temporal empirical orthogonal functions (ST-EOF) taking into account time-lag correlations between spatially separated grid points. At the second stage we merge obtained principal components into the groups related to different climate subsystems. The method is applied to decomposition of the Earth's climate system on the basis of 156 years time series of SST anomalies distributed over the Globe. For statistically correct exclusion of slow processes (trends) from data, we use large-scale ST-EOFs reconstructed from long time series of GSM simulations.

  17. Visuospatial deficits in schizophrenia: central executive and memory subsystems impairments.

    PubMed

    Leiderman, Eduardo A; Strejilevich, Sergio A

    2004-06-01

    Object and spatial visual working memory are impaired in schizophrenic patients. It is not clear if the impairments reside in each memory subsystem alone or also in the central executive component that coordinates these processes. In order to elucidate which memory component is impaired, we developed a paradigm with single spatial and object working memory tasks and dual ones with two different delays (5 and 30 s). Fifteen schizophrenic patients and 14 control subjects performed these tests. Schizophrenic patients had a poorer performance compared to normal controls in all tasks and in all time delays. Both schizophrenics and controls performed significantly worse in the object task than in the spatial task. The performance was even worse in the dual task compared to the singles ones in schizophrenic patients but not in controls. These data suggest that visuospatial performance deficits in schizophrenia are due to both visuospatial memory subsystems impairments and central executive ones. The pattern of deficits observed points to a codification or evocation deficit and not to a maintenance one. PMID:15099604

  18. Evaluation of cryogenic power conditioning subsystems for electric propulsion spacecraft

    SciTech Connect

    Das, R.S.L.; Krauthamer, S.; Frisbee, R.H.

    1996-12-31

    The power requirement of vehicles designed to transport cargo supporting a piloted expedition to Mars is in the range of megawatts. Therefore, it is imperative that the megawatt-class power processing unit designed for high-power nuclear electric propulsion vehicles using turboalternators and advanced magnetoplasmadynamic (MPD) thrusters should be such that the overall system efficiency is as high as possible with minimum system specific mass. This paper examines the use of cryogenic power conditioning subsystems to achieve that goal since they have very high efficiency. However, in the past, cryogenic power conditioning subsystems have shown complexity of design and implementation and were costly and somewhat uncertain. With recent advances in materials, devices used in power conversion and cooling methods, further improvements in efficiency and specific mass are realizable. Cryogenically cooled MOSFETs and MCTs are considered for power conversion and two configurations have been examined. It is found that a system efficiency of 92.67% and specific mass of 9.99 kg/kW{sub e} can be realized using MOSFET-based cryogenic power conditioning systems for electric propulsion spacecraft using MPD thrusters. With cryogenically cooled MCTs, the specific mass decreases to 9.77 kg/kW{sub e}, but the efficiency also decreases to 90.94%.

  19. ARES I Upper Stage Subsystems Design and Development

    NASA Technical Reports Server (NTRS)

    Frate, David T.; Senick, Paul F.; Tolbert, Carol M.

    2011-01-01

    From 2005 through early 2011, NASA conducted concept definition, design, and development of the Ares I launch vehicle. The Ares I was conceived to serve as a crew launch vehicle for beyond-low-Earth-orbit human space exploration missions as part of the Constellation Program Architecture. The vehicle was configured with a single shuttle-derived solid rocket booster first stage and a new liquid oxygen/liquid hydrogen upper stage, propelled by a single, newly developed J-2X engine. The Orion Crew Exploration Vehicle was to be mated to the forward end of the Ares I upper stage through an interface with fairings and a payload adapter. The vehicle design passed a Preliminary Design Review in August 2008, and was nearing the Critical Design Review when efforts were concluded as a result of the Constellation Program s cancellation. At NASA Glenn Research Center, four subsystems were developed for the Ares I upper stage. These were thrust vector control (TVC) for the J-2X, electrical power system (EPS), purge and hazardous gas (P&HG), and development flight instrumentation (DFI). The teams working each of these subsystems achieved 80 percent or greater design completion and extensive development testing. These efforts were extremely successful representing state-of-the-art technology and hardware advances necessary to achieve Ares I reliability, safety, availability, and performance requirements. This paper documents the designs, development test activity, and results.

  20. Orbits of Subsystems in Four Hierarchical Multiple Stars

    NASA Astrophysics Data System (ADS)

    Tokovinin, Andrei

    2016-07-01

    Seven spectroscopic orbits in nearby solar-type multiple stars are presented. The primary of the chromospherically active star HIP 9642 is a 4.8 day double-lined pair; the outer 420 year visual orbit is updated, but remains poorly constrained. HIP 12780 is a quadruple system consisting of the resolved 6.7 year pair FIN 379 Aa,Ab, for which the combined orbit, masses, and orbital parallax are determined here, and the single-lined binary Ba,Bb with a period of 27.8 days. HIP 28790 is a young quintuple system composed of two close binaries, Aa,Ab and Ba,Bb, with periods of 221 and 13 days, respectively, and a single distant component C. Its subsystem Ba,Bb is peculiar, having a spectroscopic mass ratio of 0.89 but a magnitude difference of ∼2.2 mag. HIP 64478 also contains five stars: the A-component is a 29 year visual pair with a previously known 4 day twin subsystem, while the B-component is a contact binary with a period of 5.8 hr, seen nearly pole-on.