14 CFR 27.351 - Yawing conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Yawing conditions. 27.351 Section 27.351 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.351 Yawing conditions. (a...

Evaluation of a Composite Sandwich Fuselage Side Panel with Damage and Subjected to Internal Pressure

NASA Technical Reports Server (NTRS)

Rouse, Marshall; Ambur, Damodar R.; Bodine, Jerry; Dopker, Bernhard

1997-01-01

The results from an experimental and analytical study of a composite sandwich fuselage side panel for a transport aircraft are presented. The panel has two window cutouts and three frames, and has been evaluated with internal pressure loads that generate biaxial tension loading conditions. Design limit load and design ultimate load tests have been performed on the graphite-epoxy sandwich panel with the middle frame removed to demonstrate the suitability of this two-frame design for supporting the prescribed biaxial loading conditions with twice the initial frame spacing of 20 inches. The two-frame panel was damaged by cutting a notch that originates at the edge of a cutout and extends in the panel hoop direction through the window-belt area. This panel with a notch was tested in a combined-load condition to demonstrate the structural damage tolerance at the design limit load condition. The two panel configurations successfully satisfied all design load requirements in the experimental part of the study, and the three-frame and two-frame panel responses are fully explained by the analysis results. The results of this study suggest that there is potential for using sandwich structural concepts with greater than the usual 20-in.-wide frame spacing to further reduce aircraft fuselage structural weight.

14 CFR 23.415 - Ground gust conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ground gust conditions. 23.415 Section 23... and System Loads § 23.415 Ground gust conditions. (a) The control system must be investigated as follows for control surface loads due to ground gusts and taxiing downwind: (1) If an investigation of the...

Fatigue flaw growth behavior in stiffened and unstiffened panels loaded in biaxial tension

NASA Technical Reports Server (NTRS)

Beck, E. J.

1973-01-01

The effect was investigated of biaxial loading on the flaw growth rate of 2219-T87 aluminum alloy that would be typical of Space Shuttle cryogenic tankage design. The stress distribution and stress concentration factors for several integrally stiffened panels under various loading conditions were obtained. The flaw growth behavior of both stiffened and unstiffened panels under biaxial loading conditions was determined. The effect of a complex stress state was studied by introducing flaws in fillet areas of biaxially loaded stiffened panels.

14 CFR 23.499 - Supplementary conditions for nose wheels.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Supplementary conditions for nose wheels. 23.499 Section 23.499 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... their static positions, the following conditions must be met: (a) For aft loads, the limit force...

14 CFR 23.499 - Supplementary conditions for nose wheels.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Supplementary conditions for nose wheels. 23.499 Section 23.499 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... their static positions, the following conditions must be met: (a) For aft loads, the limit force...

14 CFR 23.481 - Tail down landing conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Tail down landing conditions. 23.481 Section 23.481 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Ground Loads § 23.481 Tail down landing conditions. (a) For a tail down landing, the airplane is assumed...

46 CFR 42.20-9 - Initial conditions of loading.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) Fifty percent of the total capacity of all tanks and spaces fitted to contain consumable liquids or stores must be assumed to be distributed to accomplish the following: (i) Each tank and space fitted to... only partially filled. In the case of liquid cargoes, fully loaded means 98 percent full. (3) If the...

46 CFR 42.20-9 - Initial conditions of loading.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) Fifty percent of the total capacity of all tanks and spaces fitted to contain consumable liquids or stores must be assumed to be distributed to accomplish the following: (i) Each tank and space fitted to... only partially filled. In the case of liquid cargoes, fully loaded means 98 percent full. (3) If the...

46 CFR 42.20-9 - Initial conditions of loading.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Fifty percent of the total capacity of all tanks and spaces fitted to contain consumable liquids or stores must be assumed to be distributed to accomplish the following: (i) Each tank and space fitted to... only partially filled. In the case of liquid cargoes, fully loaded means 98 percent full. (3) If the...

46 CFR 42.20-9 - Initial conditions of loading.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) Fifty percent of the total capacity of all tanks and spaces fitted to contain consumable liquids or stores must be assumed to be distributed to accomplish the following: (i) Each tank and space fitted to... only partially filled. In the case of liquid cargoes, fully loaded means 98 percent full. (3) If the...

46 CFR 42.20-9 - Initial conditions of loading.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) Fifty percent of the total capacity of all tanks and spaces fitted to contain consumable liquids or stores must be assumed to be distributed to accomplish the following: (i) Each tank and space fitted to... only partially filled. In the case of liquid cargoes, fully loaded means 98 percent full. (3) If the...

14 CFR 25.337 - Limit maneuvering load factors.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Limit maneuvering load factors. 25.337... Conditions § 25.337 Limit maneuvering load factors. (a) Except where limited by maximum (static) lift... maneuvering load factors prescribed in this section. Pitching velocities appropriate to the corresponding pull...

Effect of gamma-ray irradiation on the unloaded animal model

NASA Astrophysics Data System (ADS)

Choi, Jong-Il; Yoon, Min-Chul; Sung, Nak-Yoon; Kim, Jae-Hun; Jong Lee, Yun; Lee, Ki-Soo; Choi, In-Ho; Nam, Gung Uk; Lee, Ju-Woon

During the space flight, human beings encountered the extreme conditions such as the cosmic ray irradiation and microgravity. There have been developed the animal models to simulate the microgravity condition in laboratory, but no study was carried out to investigate the combined effect of microgravity and exposure to irradiation. In this study, it was examined the effect of gamma irradiation on the suspension model. Rats were divided into four groups, Group I was loaded and not exposed to gamma irradiation, Group 2 was unloaded and not exposed, Group 3 was loaded and exposed to gamma irradiation at the dose of 50 mSV, and Group 4 was unloaded and exposed to gamma irradiation at the same dose. It was measured body, muscles and tissues weights and the biological analysis and the hematological response in blood samples were conducted. Anti-gravity tissue weight was only changed between loading and un-loading condition. However, there was no difference between irradiation exposed and not exposed unloaded groups. To know the difference of protein expression in anti-gravity tissues, 2 dimensional electrophoresis was performed. It has been found that the expression levels of several proteins were different by unloading condition and by irradiation exposed condition, respectively. These results provided the information on the combined effect of irradiation and microgravity to simulate space flight, and could be useful to search the candidate material for the countermeasure against space environment.

14 CFR 27.505 - Ski landing conditions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ski landing conditions. 27.505 Section 27.505 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.505 Ski landing...

14 CFR 29.505 - Ski landing conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ski landing conditions. 29.505 Section 29.505 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.505 Ski landing...

14 CFR 27.505 - Ski landing conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ski landing conditions. 27.505 Section 27.505 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.505 Ski landing...

14 CFR 29.505 - Ski landing conditions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ski landing conditions. 29.505 Section 29.505 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.505 Ski landing...

14 CFR 23.531 - Hull and main float takeoff condition.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Hull and main float takeoff condition. 23.531 Section 23.531 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Water Loads § 23.531 Hull and main float takeoff condition. For the wing and its attachment to the hull...

Response of Composite Fuselage Sandwich Side Panels Subjected to Internal Pressure and Axial Tension

NASA Technical Reports Server (NTRS)

Rouse, Marshall; Ambur, Damodar R.; Dopker, Bernard; Shah, Bharat

1998-01-01

The results from an experimental and analytical study of two composite sandwich fuselage side panels for a transport aircraft are presented. Each panel has two window cutouts and three frames and utilizes a distinctly different structural concept. These panels have been evaluated with internal pressure loads that generate biaxial tension loading conditions. Design limit load and design ultimate load tests have been performed on both panels. One of the sandwich panels was tested with the middle frame removed to demonstrate the suitability of this two-frame design for supporting the prescribed biaxial loading conditions with twice the initial frame spacing of 20 inches. A damage tolerance study was conducted on the two-frame panel by cutting a notch in the panel that originates at the edge of a cutout and extends in the panel hoop direction through the window-belt area. This panel with a notch was tested in a combined-load condition to demonstrate the structural damage tolerance at the design limit load condition. Both the sandwich panel designs successfully satisfied all desired load requirements in the experimental part of the study, and experimental results from the two-frame panel with and without damage are fully explained by the analytical results. The results of this study suggest that there is potential for using sandwich structural concepts with greater than the usual 20-in. wide frame spacing to further reduce aircraft fuselage structural weight.

Voltage profile program for the Kennedy Space Center electric power distribution system

NASA Technical Reports Server (NTRS)

1976-01-01

The Kennedy Space Center voltage profile program computes voltages at all busses greater than 1 Kv in the network under various conditions of load. The computation is based upon power flow principles and utilizes a Newton-Raphson iterative load flow algorithm. Power flow conditions throughout the network are also provided. The computer program is designed for both steady state and transient operation. In the steady state mode, automatic tap changing of primary distribution transformers is incorporated. Under transient conditions, such as motor starts etc., it is assumed that tap changing is not accomplished so that transformer secondary voltage is allowed to sag.

Condition Assessment and End-of-Life Prediction System for Electric Machines and Their Loads

NASA Technical Reports Server (NTRS)

Parlos, Alexander G.; Toliyat, Hamid A.

2005-01-01

An end-of-life prediction system developed for electric machines and their loads could be used in integrated vehicle health monitoring at NASA and in other government agencies. This system will provide on-line, real-time condition assessment and end-of-life prediction of electric machines (e.g., motors, generators) and/or their loads of mechanically coupled machinery (e.g., pumps, fans, compressors, turbines, conveyor belts, magnetic levitation trains, and others). In long-duration space flight, the ability to predict the lifetime of machinery could spell the difference between mission success or failure. Therefore, the system described here may be of inestimable value to the U.S. space program. The system will provide continuous monitoring for on-line condition assessment and end-of-life prediction as opposed to the current off-line diagnoses.

14 CFR 29.351 - Yawing conditions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Yawing conditions. 29.351 Section 29.351 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... furnishing the reacting inertia forces; and (2) Maximum main rotor speed. (b) To produce the load required in...

14 CFR 27.351 - Yawing conditions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Yawing conditions. 27.351 Section 27.351 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... reacting inertia forces; and (2) Maximum main rotor speed. (b) To produce the load required in paragraph (a...

14 CFR 27.351 - Yawing conditions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Yawing conditions. 27.351 Section 27.351 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... reacting inertia forces; and (2) Maximum main rotor speed. (b) To produce the load required in paragraph (a...

14 CFR 25.351 - Yaw maneuver conditions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Yaw maneuver conditions. 25.351 Section 25.351 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... airplane inertia forces. In computing the tail loads the yawing velocity may be assumed to be zero. (a...

14 CFR 25.351 - Yaw maneuver conditions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Yaw maneuver conditions. 25.351 Section 25.351 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... airplane inertia forces. In computing the tail loads the yawing velocity may be assumed to be zero. (a...

14 CFR 29.351 - Yawing conditions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Yawing conditions. 29.351 Section 29.351 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... furnishing the reacting inertia forces; and (2) Maximum main rotor speed. (b) To produce the load required in...

10 CFR 434.201 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... includes any non-heating season pilot input loss. Area of the space (A): the horizontal lighted area of a... doors of a building. Integrated part-load value (IPLV): a single-number figure of merit based on part-load EER or COP expressing part-load efficiency for air-conditioning and heat pump equipment on the...

Composite load spectra for select space propulsion structural components

NASA Technical Reports Server (NTRS)

Newell, J. F.; Ho, H. W.; Kurth, R. E.

1991-01-01

The work performed to develop composite load spectra (CLS) for the Space Shuttle Main Engine (SSME) using probabilistic methods. The three methods were implemented to be the engine system influence model. RASCAL was chosen to be the principal method as most component load models were implemented with the method. Validation of RASCAL was performed. High accuracy comparable to the Monte Carlo method can be obtained if a large enough bin size is used. Generic probabilistic models were developed and implemented for load calculations using the probabilistic methods discussed above. Each engine mission, either a real fighter or a test, has three mission phases: the engine start transient phase, the steady state phase, and the engine cut off transient phase. Power level and engine operating inlet conditions change during a mission. The load calculation module provides the steady-state and quasi-steady state calculation procedures with duty-cycle-data option. The quasi-steady state procedure is for engine transient phase calculations. In addition, a few generic probabilistic load models were also developed for specific conditions. These include the fixed transient spike model, the poison arrival transient spike model, and the rare event model. These generic probabilistic load models provide sufficient latitude for simulating loads with specific conditions. For SSME components, turbine blades, transfer ducts, LOX post, and the high pressure oxidizer turbopump (HPOTP) discharge duct were selected for application of the CLS program. They include static pressure loads and dynamic pressure loads for all four components, centrifugal force for the turbine blade, temperatures of thermal loads for all four components, and structural vibration loads for the ducts and LOX posts.

Adaptation to high throughput batch chromatography enhances multivariate screening.

PubMed

Barker, Gregory A; Calzada, Joseph; Herzer, Sibylle; Rieble, Siegfried

2015-09-01

High throughput process development offers unique approaches to explore complex process design spaces with relatively low material consumption. Batch chromatography is one technique that can be used to screen chromatographic conditions in a 96-well plate. Typical batch chromatography workflows examine variations in buffer conditions or comparison of multiple resins in a given process, as opposed to the assessment of protein loading conditions in combination with other factors. A modification to the batch chromatography paradigm is described here where experimental planning, programming, and a staggered loading approach increase the multivariate space that can be explored with a liquid handling system. The iterative batch chromatography (IBC) approach is described, which treats every well in a 96-well plate as an individual experiment, wherein protein loading conditions can be varied alongside other factors such as wash and elution buffer conditions. As all of these factors are explored in the same experiment, the interactions between them are characterized and the number of follow-up confirmatory experiments is reduced. This in turn improves statistical power and throughput. Two examples of the IBC method are shown and the impact of the load conditions are assessed in combination with the other factors explored. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Estimated Muscle Loads During Squat Exercise in Microgravity Conditions

NASA Technical Reports Server (NTRS)

Fregly, Christopher D.; Kim, Brandon T.; Li, Zhao; DeWitt, John K.; Fregly, Benjamin J.

2012-01-01

Loss of muscle mass in microgravity is one of the primary factors limiting long-term space flight. NASA researchers have developed a number of exercise devices to address this problem. The most recent is the Advanced Resistive Exercise Device (ARED), which is currently used by astronauts on the International Space Station (ISS) to emulate typical free-weight exercises in microgravity. ARED exercise on the ISS is intended to reproduce Earth-level muscle loads, but the actual muscle loads produced remain unknown as they cannot currently be measured directly. In this study we estimated muscle loads experienced during squat exercise on ARED in microgravity conditions representative of Mars, the moon, and the ISS. The estimates were generated using a subject-specific musculoskeletal computer model and ARED exercise data collected on Earth. The results provide insight into the capabilities and limitations of the ARED machine.

Application of Avatars in Display Design to Support Spatial Awareness under Varying Workload Conditions

DTIC Science & Technology

2006-09-01

36 5. NASA - TLX over Increased Workload ................................... 37 viii C...AERONAUTICS AND SPACE ADMINISTRATION – TASK LOAD INDEX ( NASA - TLX )................................................................ 89 APPENDIX H...environments are the NASA Task Load Index ( NASA - TLX ) and the Subjective Workload Assessment Techniques (SWAT) which have subscales assessing loads for time

14 CFR 25.305 - Strength and deformation.

Code of Federal Regulations, 2013 CFR

2013-01-01

... strength is shown by dynamic tests simulating actual load conditions, the 3-second limit does not apply. Static tests conducted to ultimate load must include the ultimate deflections and ultimate deformation....305 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT...

14 CFR 25.305 - Strength and deformation.

Code of Federal Regulations, 2012 CFR

2012-01-01

... strength is shown by dynamic tests simulating actual load conditions, the 3-second limit does not apply. Static tests conducted to ultimate load must include the ultimate deflections and ultimate deformation....305 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT...

14 CFR 25.305 - Strength and deformation.

Code of Federal Regulations, 2014 CFR

2014-01-01

... strength is shown by dynamic tests simulating actual load conditions, the 3-second limit does not apply. Static tests conducted to ultimate load must include the ultimate deflections and ultimate deformation....305 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT...

14 CFR 25.305 - Strength and deformation.

Code of Federal Regulations, 2010 CFR

2010-01-01

... strength is shown by dynamic tests simulating actual load conditions, the 3-second limit does not apply. Static tests conducted to ultimate load must include the ultimate deflections and ultimate deformation....305 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT...

14 CFR 25.305 - Strength and deformation.

Code of Federal Regulations, 2011 CFR

2011-01-01

... strength is shown by dynamic tests simulating actual load conditions, the 3-second limit does not apply. Static tests conducted to ultimate load must include the ultimate deflections and ultimate deformation....305 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT...

Load cell verification of the uprated high pressure oxygen turbopump for the Space Shuttle Main Engine

NASA Technical Reports Server (NTRS)

Beatty, R. F.; Hine, M. J.

1986-01-01

The high pressure turbomachinery of the Space Shuttle Main Engine has the highest power-to-weight ratio of any operational machine known. Subsynchronous rotor whirl of the high pressure oxygen turbopump occurred in development testing at full-power level (109 percent thrust). The means by which the turbopump was successfully uprated is presented herein. The subsynchronous motion was determined to be driven by impeller destabilizing forces in combination with low net damping and bearing degradation. The degradation resulted from ball wear due primarily to an excessive loading condition of operating too near the lightly damped rotor second critical speed while under a large static load and, secondarily, from reverse bearing loading or loss of internal clearance and coolant during simulated flight conditions. The rotor response was reduced by stiffening the shaft and supports, optimizing the stiffness and damping of annular seals, and increasing the bearing deadband. The uprated oxygen turbopump configuration was verified by converting the pump and bearing support into a load cell for the purpose of systematically quantifying the load reduction benefits relative to baseline turbopumps. The damped second critical speed margin and the load sharing have been substantially improved which has resulted in reduced bearing loads for improved service life of the machine at full-power level.

Cornering characteristics of the main-gear tire of the space shuttle orbiter

NASA Technical Reports Server (NTRS)

Daugherty, Robert H.; Stubbs, Sandy M.; Robinson, Martha P.

1988-01-01

An experimental investigation was conducted at the NASA Langley Research Center to study the effects of various vertical load and yaw angle conditions on the cornering behavior of the Space Shuttle Orbiter main gear tire. Measured parameters included side and drag force, side and drag force coefficients, aligning torque, and overturning torque. Side force coefficient was found to increase as yaw angle was increased, but decreased as the vertical load was increased. Drag force was found to increase as vertical load was increased at constant yaw angles. Aligning torque measurements indicated that the tire is stable in yaw.

Design and fabrication of brazed Rene 41 honeycomb sandwich structural panels for advanced space transportation systems

NASA Technical Reports Server (NTRS)

Hepler, A. K.; Swegle, A. R.

1981-01-01

The design and fabrication of two large brazed Rene 41 honeycomb panels, the establishment of a test plan, the design and fabrication of a test fixture to subject the panels to cyclic thermal gradients and mechanical loads equivalent to those imposed on an advanced space transportation vehicle during its boost and entry trajectories are discussed. The panels will be supported at four points, creating three spans. The outer spans are 45.7 cm (18 in.) and the center span 76.2 cm (30 in). Specimen width is 30.5 cm (12 in.). The panels were primarily designed by boost conditions simulated by subjecting the panels to liquid nitrogen, 77K (-320 F) on one side and 455K (360 F) on the other side and by mechanically imposing loads representing vehicle fuel pressure loads. Entry conditions were simulated by radiant heating to 1034K (1400 F). The test program subjected the panels to 500 boost thermal conditions. Results are presented.

Cornering and wear behavior of the Space Shuttle Orbiter main gear tire

NASA Technical Reports Server (NTRS)

Daugherty, Robert H.; Stubbs, Sandy M.

1987-01-01

One of the factors needed to describe the handling characteristics of the Space Shuttle Orbiter during the landing rollout is the response of the vehicle's tires to variations in load and yaw angle. An experimental investigation of the cornering characteristics of the Orbiter main gear tires was conducted at the NASA Langley Research Center Aircraft Landing Dynamics Facility. This investigation compliments earlier work done to define the Orbiter nose tire cornering characteristics. In the investigation, the effects of load and yaw angle were evaluated by measuring parameters such as side load and drag load, and obtaining measurements of aligning torque. Because the tire must operate on an extremely rough runway at the Shuttle Landing Facility at Kennedy Space Center (KSC), tests were also conducted to describe the wear behavior of the tire under various conditions on a simulated KSC runway surface. Mathematical models for both the cornering and the wear behavior are discussed.

Transient Pressure Measurements in the Vaneless Space of a Francis Turbine during Load Acceptances from Minimum Load

NASA Astrophysics Data System (ADS)

Goyal, R.; Gandhi, B. K.; Cervantes, M. J.

2018-06-01

Increased penetration of solar and the wind impels the designers of the hydroelectric power generation unit to provide more flexibility in operation for the stability of the grid. The power generating unit includes turbine which needs to sustain sudden change in its operating conditions. Thus, the hydraulic turbine experiences more transients per day which result in chronic problems such as fatigue to the runner, instrument malfunctioning, vibrations, wear and tear etc. This paper describes experiments performed on a high model (1.5:1) Francis turbine for load acceptances from the minimum load. The experiments presented in the paper are the part of Francis-99 workshop which aims to determine the performance of numerical models in simulations of model Francis turbine under steady and transient operating conditions. The aim of the paper is to present the transient pressure variation in the vaneless space of a Francis turbine where high-frequency pulsations are normally expected. For this, two pressure sensors, VL1 and VL2, are mounted at the vaneless space, one near the beginning of the spiral casing and the other before the end of the spiral casing. Both are used to capture the unsteady pressure field developed in the space between guide vanes and runner inlet. The time-resolved pressure signals are analyzed and presented during the transient to observe the pressure variation and dominant frequencies of pulsations.

Full-Scale System for Quantifying Loads and Leak Rates of Seals for Space Applications

NASA Technical Reports Server (NTRS)

Dunlap, Patrick H., Jr.; Steinetz, Bruce M.; Daniels, Christopher C.; Wasowski, Janice L.; Robbie, Malcolm G.; Erker, Arthur H.; Drlik, Gary J.; Mayer, John J.

2010-01-01

NASA is developing advanced space-rated vacuum seals in support of future space exploration missions to low-Earth orbit and other destinations. These seals may be 50 to 60 in. (127 to 152 cm) in diameter and must exhibit extremely low leak rates to ensure that astronauts have sufficient breathable air for extended missions to the International Space Station or the Moon. Seal compression loads must be below prescribed limits so as not to overload the mechanisms that compress them during docking or mating, and seal adhesion forces must be low to allow two mated systems to separate when required. NASA Glenn Research Center has developed a new test apparatus to measure leak rates and compression and adhesion loads of candidate full-scale seals under simulated thermal, vacuum, and engagement conditions. Tests can be performed in seal-on-seal or seal-on-flange configurations at temperatures from -76 to 140 F (-60 to 60 C) under operational pressure gradients. Nominal and off-nominal mating conditions (e.g., incomplete seal compression) can also be simulated. This paper describes the main design features of the test apparatus as well as techniques used to overcome some of the design challenges.

14 CFR 25.489 - Ground handling conditions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ground handling conditions. 25.489 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.489 Ground handling conditions... ground handling conditions). No wing lift may be considered. The shock absorbers and tires may be assumed...

14 CFR 25.489 - Ground handling conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ground handling conditions. 25.489 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.489 Ground handling conditions... ground handling conditions). No wing lift may be considered. The shock absorbers and tires may be assumed...

14 CFR 23.471 - General.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false General. 23.471 Section 23.471 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... forces that act upon an airplane structure. In each specified ground load condition, the external...

14 CFR 23.471 - General.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false General. 23.471 Section 23.471 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... forces that act upon an airplane structure. In each specified ground load condition, the external...

14 CFR 23.471 - General.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false General. 23.471 Section 23.471 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... forces that act upon an airplane structure. In each specified ground load condition, the external...

14 CFR 23.471 - General.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false General. 23.471 Section 23.471 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... forces that act upon an airplane structure. In each specified ground load condition, the external...

14 CFR 23.471 - General.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false General. 23.471 Section 23.471 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... forces that act upon an airplane structure. In each specified ground load condition, the external...

The contribution of working memory to divided attention.

PubMed

Santangelo, Valerio; Macaluso, Emiliano

2013-01-01

Previous studies have indicated that increasing working memory (WM) load can affect the attentional selection of signals originating from one object/location. Here we assessed whether WM load affects also the selection of multiple objects/locations (divided attention). Participants monitored either two object-categories (vs. one category; object-based divided attention) or two locations (vs. one location; space-based divided attention) while maintaining in WM either a variable number of objects (object-based WM load) or locations (space-based WM load). Behavioural results showed that WM load affected attentional performance irrespective of divided or focused attention. However, fMRI results showed that the activity associated with object-based divided attention increased linearly with increasing object-based WM load in the left and right intraparietal sulcus (IPS); while, in the same areas, activity associated with space-based divided attention was not affected by any type of WM load. These findings support the hypothesis that WM contributes to the maintenance of resource-demanding attentional sets in a domain-specific manner. Moreover, the dissociable impact of WM load on performance and brain activity suggests that increased IPS activation reflects a recruitment of additional, domain-specific processing resources that enable dual-task performance under conditions of high WM load and high attentional demand. Copyright © 2011 Wiley Periodicals, Inc.

Water impact analysis of space shuttle solid rocket motor by the finite element method

NASA Technical Reports Server (NTRS)

Buyukozturk, O.; Hibbitt, H. D.; Sorensen, E. P.

1974-01-01

Preliminary analysis showed that the doubly curved triangular shell elements were too stiff for these shell structures. The doubly curved quadrilateral shell elements were found to give much improved results. A total of six load cases were analyzed in this study. The load cases were either those resulting from a static test using reaction straps to simulate the drop conditions or under assumed hydrodynamic conditions resulting from a drop test. The latter hydrodynamic conditions were obtained through an emperical fit of available data. Results obtained from a linear analysis were found to be consistent with results obtained elsewhere with NASTRAN and BOSOR. The nonlinear analysis showed that the originally assumed loads would result in failure of the shell structures. The nonlinear analysis also showed that it was useful to apply internal pressure as a stabilizing influence on collapse. A final analysis with an updated estimate of load conditions resulted in linear behavior up to full load.

Strategy Guideline. Compact Air Distribution Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burdick, Arlan

2013-06-01

This guideline discusses the benefits and challenges of using a compact air distribution system to handle the reduced loads and reduced air volume needed to condition the space within an energy efficient home. The decision criteria for a compact air distribution system must be determined early in the whole-house design process, considering both supply and return air design. However, careful installation of a compact air distribution system can result in lower material costs from smaller equipment, shorter duct runs, and fewer outlets; increased installation efficiencies, including ease of fitting the system into conditioned space; lower loads on a better balancedmore » HVAC system, and overall improved energy efficiency of the home.« less

46 CFR 45.157 - Scuppers and gravity drains.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Scuppers and gravity drains. 45.157 Section 45.157 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Conditions of Assignment § 45.157 Scuppers and gravity drains. Scuppers and gravity deck drains from spaces...

46 CFR 45.157 - Scuppers and gravity drains.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Scuppers and gravity drains. 45.157 Section 45.157 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Conditions of Assignment § 45.157 Scuppers and gravity drains. Scuppers and gravity deck drains from spaces...

46 CFR 45.157 - Scuppers and gravity drains.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Scuppers and gravity drains. 45.157 Section 45.157 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Conditions of Assignment § 45.157 Scuppers and gravity drains. Scuppers and gravity deck drains from spaces...

46 CFR 45.157 - Scuppers and gravity drains.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Scuppers and gravity drains. 45.157 Section 45.157 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Conditions of Assignment § 45.157 Scuppers and gravity drains. Scuppers and gravity deck drains from spaces...

46 CFR 45.157 - Scuppers and gravity drains.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Scuppers and gravity drains. 45.157 Section 45.157 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Conditions of Assignment § 45.157 Scuppers and gravity drains. Scuppers and gravity deck drains from spaces...

Selecting boundary conditions in physiological strain analysis of the femur: Balanced loads, inertia relief method and follower load.

PubMed

Heyland, Mark; Trepczynski, Adam; Duda, Georg N; Zehn, Manfred; Schaser, Klaus-Dieter; Märdian, Sven

2015-12-01

Selection of boundary constraints may influence amount and distribution of loads. The purpose of this study is to analyze the potential of inertia relief and follower load to maintain the effects of musculoskeletal loads even under large deflections in patient specific finite element models of intact or fractured bone compared to empiric boundary constraints which have been shown to lead to physiological displacements and surface strains. The goal is to elucidate the use of boundary conditions in strain analyses of bones. Finite element models of the intact femur and a model of clinically relevant fracture stabilization by locking plate fixation were analyzed with normal walking loading conditions for different boundary conditions, specifically re-balanced loading, inertia relief and follower load. Peak principal cortex surface strains for different boundary conditions are consistent (maximum deviation 13.7%) except for inertia relief without force balancing (maximum deviation 108.4%). Influence of follower load on displacements increases with higher deflection in fracture model (from 3% to 7% for force balanced model). For load balanced models, follower load had only minor influence, though the effect increases strongly with higher deflection. Conventional constraints of fixed nodes in space should be carefully reconsidered because their type and position are challenging to justify and for their potential to introduce relevant non-physiological reaction forces. Inertia relief provides an alternative method which yields physiological strain results. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

Modeling of rolling element bearing mechanics

NASA Technical Reports Server (NTRS)

Greenhill, L. M.

1991-01-01

Roller element bearings provide the primary mechanical interface between rotating and nonrotating components in the high performance turbomachinery of the Space Shuttle Main Engine (SSME). Knowledge of bearing behavior under various loading and environmental conditions is essential to predicting and understanding the overall behavior of turbopumps, including rotordynamic stability, critical speeds and bearing life. The objective is to develop mathematical models and computer programs to describe the mechanical behavior of ball and cylinder roller bearings under the loading and environmental conditions encountered in the SSME and future high performance rocket engines. This includes characteristics such as nonlinear load/motion relationships, stiffness and damping, rolling element loads for life prediction, and roller and cage stability.

Space Shuttle Transportation (Roll-Out) Loads Diagnostics

NASA Technical Reports Server (NTRS)

Elliott, Kenny B.; Buehrle, Ralph D.; James, George H.; Richart, Jene A.

2005-01-01

The Space Transportation System (STS) consists of three primary components; an Orbiter Vehicle, an External Fuel Tank, and two Solid Rocket Boosters. The Orbiter Vehicle and Solid Rocket Boosters are reusable components, and as such, they are susceptible to durability issues. Recently, the fatigue load spectra for these components have been updated to include load histories acquired during the rollout phase of the STS processing for flight. Using traditional program life assessment techniques, the incorporation of these "rollout" loads produced unacceptable life estimates for certain Orbiter structural members. As a result, the Space Shuttle System Engineering and Integration Office has initiated a program to re-assess the method used for developing the "rollout" loads and performing the life assessments. In the fall of 2003 a set of tests were preformed to provide information to either validate existing load spectra estimation techniques or generate new load spectra estimation methods. Acceleration and strain data were collected from two rollouts of a partial-stack configuration of the Space Shuttle. The partial stack configuration consists of two Solid Rocket Boosters tied together at the upper External Tank attachment locations mounted on the Mobile Launch Platform carried by a Crawler Transporter (CT). In the current analysis, the data collected from this test is examined for consistency in speed, surface condition effects, and the characterization of the forcing function. It is observed that the speed of the CT is relatively stable. The dynamic response acceleration of the partial-stack is slightly sensitive to the surface condition of the road used for transport, and the dynamic response acceleration of the partial-stack generally increases as the transport speed increases. However, the speed sensitivity is dependent on the measurement location. Finally, the character of the forcing function is narrow-banded with the primary drivers being harmonics of two CT speed dependent excitations. One source is an excitation due to the CT treads striking the road surface, and the second is unknown.

14 CFR 25.483 - One-gear landing conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false One-gear landing conditions. 25.483 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.483 One-gear landing conditions. For the one-gear landing conditions, the airplane is assumed to be in the level attitude and to...

Structural tests on a tile/strain isolation pad thermal protection system. [space shuttles

NASA Technical Reports Server (NTRS)

Williams, J. G.

1980-01-01

The aluminum skin of the space shuttle is covered by a thermal protection system (TPS) consisting of a low density ceramic tile bonded to a matted-felt material called strain insulation pad (SIP). The structural characteristics of the TPS were studied experimentally under selected extreme load conditions. Three basic types of loads were imposed: tension, eccentrically applied tension, and combined in-plane force and transverse pressure. For some tests, transverse pressure was applied rapidly to simulate a transient shock wave passing over the tile. The failure mode for all specimens involved separation of the tile from the SIP at the silicone rubber bond interface. An eccentrically applied tension load caused the tile to separate from the SIP at loads lower than experienced at failure for pure tension loading. Moderate in-plane as well as shock loading did not cause a measurable reduction in the TPS ultimate failure strength. A strong coupling, however, was exhibited between in-plane and transverse loads and displacements.

46 CFR 171.068 - Special considerations for Type I subdivision for vessels on short international voyages.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Location Uniform average permeability 10 (a−c) Machinery Space 85+____ v 35(b) Volume Forward of Machinery Space 95−__ v 35(b) Volume Aft of Machinery Space 95−___ v For each location specified in this table— a=volume below the margin line of all spaces that, in the full load condition, normally contain no cargo...

46 CFR 171.068 - Special considerations for Type I subdivision for vessels on short international voyages.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Location Uniform average permeability 10 (a−c) Machinery Space 85+____ v 35(b) Volume Forward of Machinery Space 95−__ v 35(b) Volume Aft of Machinery Space 95−___ v For each location specified in this table— a=volume below the margin line of all spaces that, in the full load condition, normally contain no cargo...

46 CFR 171.068 - Special considerations for Type I subdivision for vessels on short international voyages.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Location Uniform average permeability 10 (a−c) Machinery Space 85+____ v 35(b) Volume Forward of Machinery Space 95−__ v 35(b) Volume Aft of Machinery Space 95−___ v For each location specified in this table— a=volume below the margin line of all spaces that, in the full load condition, normally contain no cargo...

46 CFR 171.068 - Special considerations for Type I subdivision for vessels on short international voyages.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Location Uniform average permeability 10 (a−c) Machinery Space 85+____ v 35(b) Volume Forward of Machinery Space 95−__ v 35(b) Volume Aft of Machinery Space 95−___ v For each location specified in this table— a=volume below the margin line of all spaces that, in the full load condition, normally contain no cargo...

Failure Criterion For Isotropic Time Dependent Materials Which Accounts for Multi-Axial Loading

NASA Technical Reports Server (NTRS)

Richardson, D. E.; Anderson, G. L.; Macon, D. J.

2003-01-01

The Space Shuttle's Reusable Solid Rocket Motor (RSRM) nozzle program has recently conducted testing to characterize the effects of multi-axial loading, temperature and time on the failure characteristics of TIGA321, EA913NA, EA946 (three filled epoxy adhesives). From the test data a "Multi-Axial, Temperature, and Time Dependent" or MATT failure criterion was developed. It is shown that this criterion simplifies, for constant load and constant load rate conditions, into a form that can be easily used for stress analysis. Failure for TIGA321 and EA913NA are characterized below their glass transition temperature. Failure for EA946 is characterized for conditions that pass through its glass transition. The MATT failure criterion is shown to be accurate for a wide range of conditions for these adhesives.

Field Study of Performance, Comfort, and Sizing of Two Variable-Speed Heat Pumps Installed in a Single 2-Story Residence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munk, Jeffrey D; Odukomaiya, Adewale O; Gehl, Anthony C

2014-01-01

With the recent advancements in the application of variable-speed (VS) compressors to residential HVAC systems, opportunities are now available to size heat pumps (HPs) to more effectively meet heating and cooling loads in many of the climate zones in the US with limited use of inefficient resistance heat. This is in contrast to sizing guidance for traditional single-speed HPs that limits the ability to oversize with regard to cooling loads, because of risks of poor dehumidification during the cooling season and increased cycling losses. VS-drive HPs can often run at 30-40% of their rated cooling capacity to reduce cycling losses,more » and can adjust fan speed to provide better indoor humidity control. Detailed air-side performance data was collected on two VS-drive heat pumps installed in a single unoccupied research house in Knoxville, TN, a mixed-humid climate. One system provided space conditioning for the upstairs, while the other unit provided space conditioning for the downstairs. Occupancy was simulated by operating the lights, shower, appliances, other plug loads, etc. to simulate the sensible and latent loads imposed on the building space by internal electric loads and human occupants according to the Building America Research Benchmark (2008). The seasonal efficiency and energy use of the units are calculated. Annual energy use is compared to that of the single speed minimum efficiency HPs tested in the same house previously. Sizing of the units relative to the measured building load and manual J design load calculations is examined. The impact of the unit sizing with regards to indoor comfort is also evaluated.« less

Optimum design of structures subject to general periodic loads

NASA Technical Reports Server (NTRS)

Reiss, Robert; Qian, B.

1989-01-01

A simplified version of Icerman's problem regarding the design of structures subject to a single harmonic load is discussed. The nature of the restrictive conditions that must be placed on the design space in order to ensure an analytic optimum are discussed in detail. Icerman's problem is then extended to include multiple forcing functions with different driving frequencies. And the conditions that now must be placed upon the design space to ensure an analytic optimum are again discussed. An important finding is that all solutions to the optimality condition (analytic stationary design) are local optima, but the global optimum may well be non-analytic. The more general problem of distributing the fixed mass of a linear elastic structure subject to general periodic loads in order to minimize some measure of the steady state deflection is also considered. This response is explicitly expressed in terms of Green's functional and the abstract operators defining the structure. The optimality criterion is derived by differentiating the response with respect to the design parameters. The theory is applicable to finite element as well as distributed parameter models.

Extending Cognitive Load Theory to Incorporate Working Memory Resource Depletion: Evidence from the Spacing Effect

ERIC Educational Resources Information Center

Chen, Ouhao; Castro-Alonso, Juan C.; Paas, Fred; Sweller, John

2018-01-01

Depletion of limited working memory resources may occur following extensive mental effort resulting in decreased performance compared to conditions requiring less extensive mental effort. This "depletion effect" can be incorporated into cognitive load theory that is concerned with using the properties of human cognitive architecture,…

Dry etch challenges for CD shrinkage in memory process

NASA Astrophysics Data System (ADS)

Matsushita, Takaya; Matsumoto, Takanori; Mukai, Hidefumi; Kyoh, Suigen; Hashimoto, Kohji

2015-03-01

Line pattern collapse attracts attention as a new problem of the L&S formation in sub-20nm H.P feature. Line pattern collapse that occurs in a slight non-uniformity of adjacent CD (Critical dimension) space using double patterning process has been studied with focus on micro-loading effect in Si etching. Bias RF pulsing plasma etching process using low duty cycle helped increase of selectivity Si to SiO2. In addition to the effect of Bias RF pulsing process, the thin mask obtained from improvement of selectivity has greatly suppressed micro-loading in Si etching. However it was found that micro-loading effect worsen again in sub-20nm space width. It has been confirmed that by using cycle etch process to remove deposition with CFx based etching micro-loading effect could be suppressed. Finally, Si etching process condition using combination of results above could provide finer line and space without "line pattern collapse" in sub-20nm.

Debris/ice/TPS assessment and photographic analysis for Shuttle Mission STS-28R

NASA Technical Reports Server (NTRS)

Stevenson, Charles G.; Katnik, Gregory N.; Higginbotham, Scott A.

1989-01-01

A Debris/Ice/TPS assessment and photographic analysis was conducted for Space Shuttle Mission STS-28R. Debris inspections of the flight elements and launch pad are performed before and after launch. Ice/Frost conditions on the External Tank are assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography is analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. The debris/ice/TPS conditions and photographic analysis of Mission STS-28R is documented along with their overall effect on the Space Shuttle Program.

14 CFR 23.483 - One-wheel landing conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false One-wheel landing conditions. 23.483... Ground Loads § 23.483 One-wheel landing conditions. For the one-wheel landing condition, the airplane is assumed to be in the level attitude and to contact the ground on one side of the main landing gear. In...

Space Power Facility Reverberation Chamber Calibration Report

NASA Technical Reports Server (NTRS)

Lewis, Catherine C.; Dolesh, Robert J.; Garrett, Michael J.

2014-01-01

This document describes the process and results of calibrating the Space Environmental Test EMI Test facility at NASA Plum Brook Space Power Facility according to the specifications of IEC61000-4-21 for susceptibility testing from 100 MHz to 40 GHz. The chamber passed the field uniformity test, in both the empty and loaded conditions, making it the world's largest Reverberation Chamber.

Feedback linearization based control of a variable air volume air conditioning system for cooling applications.

PubMed

Thosar, Archana; Patra, Amit; Bhattacharyya, Souvik

2008-07-01

Design of a nonlinear control system for a Variable Air Volume Air Conditioning (VAVAC) plant through feedback linearization is presented in this article. VAVAC systems attempt to reduce building energy consumption while maintaining the primary role of air conditioning. The temperature of the space is maintained at a constant level by establishing a balance between the cooling load generated in the space and the air supply delivered to meet the load. The dynamic model of a VAVAC plant is derived and formulated as a MIMO bilinear system. Feedback linearization is applied for decoupling and linearization of the nonlinear model. Simulation results for a laboratory scale plant are presented to demonstrate the potential of keeping comfort and maintaining energy optimal performance by this methodology. Results obtained with a conventional PI controller and a feedback linearizing controller are compared and the superiority of the proposed approach is clearly established.

14 CFR 23.529 - Hull and main float landing conditions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Hull and main float landing conditions. 23... Water Loads § 23.529 Hull and main float landing conditions. (a) Symmetrical step, bow, and stern... directed perpendicularly to the keel line. (b) Unsymmetrical landing for hull and single float seaplanes...

14 CFR 25.531 - Hull and main float takeoff condition.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Hull and main float takeoff condition. 25... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Water Loads § 25.531 Hull and main float takeoff condition. For the wing and its attachment to the hull or main float— (a) The aerodynamic...

Advanced resistive exercise device

NASA Technical Reports Server (NTRS)

Raboin, Jasen L. (Inventor); Niebuhr, Jason (Inventor); Cruz, Santana F. (Inventor); Lamoreaux, Christopher D. (Inventor)

2008-01-01

The present invention relates to an exercise device, which includes a vacuum cylinder and a flywheel. The flywheel provides an inertial component to the load, which is particularly well suited for use in space as it simulates exercising under normal gravity conditions. Also, the present invention relates to an exercise device, which has a vacuum cylinder and a load adjusting armbase assembly.

Characterization of Solid Polymers, Ceramic Gap Filler, and Closed-Cell Polymer Foam Using Low-Load Test Methods

NASA Technical Reports Server (NTRS)

Herring, Helen M.

2008-01-01

Various solid polymers, polymer-based composites, and closed-cell polymer foam are being characterized to determine their mechanical properties, using low-load test methods. The residual mechanical properties of these materials after environmental exposure or extreme usage conditions determines their value in aerospace structural applications. In this experimental study, four separate polymers were evaluated to measure their individual mechanical responses after thermal aging and moisture exposure by dynamic mechanical analysis. A ceramic gap filler, used in the gaps between the tiles on the Space Shuttle, was also tested, using dynamic mechanical analysis to determine material property limits during flight. Closed-cell polymer foam, used for the Space Shuttle External Tank insulation, was tested under low load levels to evaluate how the foam's mechanical properties are affected by various loading and unloading scenarios.

Dynamic Load Predictions for Launchers Using Extra-Large Eddy Simulations X-Les

NASA Astrophysics Data System (ADS)

Maseland, J. E. J.; Soemarwoto, B. I.; Kok, J. C.

2005-02-01

Flow-induced unsteady loads can have a strong impact on performance and flight characteristics of aerospace vehicles and therefore play a crucial role in their design and operation. Complementary to costly flight tests and delicate wind-tunnel experiments, unsteady loads can be calculated using time-accurate Computational Fluid Dynamics. A capability to accurately predict the dynamic loads on aerospace structures at flight Reynolds numbers can be of great value for the design and analysis of aerospace vehicles. Advanced space launchers are subject to dynamic loads in the base region during the ascent to space. In particular the engine and nozzle experience aerodynamic pressure fluctuations resulting from massive flow separations. Understanding these phenomena is essential for performance enhancements for future launchers which operate a larger nozzle. A new hybrid RANS-LES turbulence modelling approach termed eXtra-Large Eddy Simulations (X-LES) holds the promise to capture the flow structures associated with massive separations and enables the prediction of the broad-band spectrum of dynamic loads. This type of method has become a focal point, reducing the cost of full LES, driven by the demand for their applicability in an industrial environment. The industrial feasibility of X-LES simulations is demonstrated by computing the unsteady aerodynamic loads on the main-engine nozzle of a generic space launcher configuration. The potential to calculate the dynamic loads is qualitatively assessed for transonic flow conditions in a comparison to wind-tunnel experiments. In terms of turn-around-times, X-LES computations are already feasible within the time-frames of the development process to support the structural design. Key words: massive separated flows; buffet loads; nozzle vibrations; space launchers; time-accurate CFD; composite RANS-LES formulation.

Impact of Spatial and Verbal Short-Term Memory Load on Auditory Spatial Attention Gradients.

PubMed

Golob, Edward J; Winston, Jenna; Mock, Jeffrey R

2017-01-01

Short-term memory load can impair attentional control, but prior work shows that the extent of the effect ranges from being very general to very specific. One factor for the mixed results may be reliance on point estimates of memory load effects on attention. Here we used auditory attention gradients as an analog measure to map-out the impact of short-term memory load over space. Verbal or spatial information was maintained during an auditory spatial attention task and compared to no-load. Stimuli were presented from five virtual locations in the frontal azimuth plane, and subjects focused on the midline. Reaction times progressively increased for lateral stimuli, indicating an attention gradient. Spatial load further slowed responses at lateral locations, particularly in the left hemispace, but had little effect at midline. Verbal memory load had no (Experiment 1), or a minimal (Experiment 2) influence on reaction times. Spatial and verbal load increased switch costs between memory encoding and attention tasks relative to the no load condition. The findings show that short-term memory influences the distribution of auditory attention over space; and that the specific pattern depends on the type of information in short-term memory.

Impact of Spatial and Verbal Short-Term Memory Load on Auditory Spatial Attention Gradients

PubMed Central

Golob, Edward J.; Winston, Jenna; Mock, Jeffrey R.

2017-01-01

Short-term memory load can impair attentional control, but prior work shows that the extent of the effect ranges from being very general to very specific. One factor for the mixed results may be reliance on point estimates of memory load effects on attention. Here we used auditory attention gradients as an analog measure to map-out the impact of short-term memory load over space. Verbal or spatial information was maintained during an auditory spatial attention task and compared to no-load. Stimuli were presented from five virtual locations in the frontal azimuth plane, and subjects focused on the midline. Reaction times progressively increased for lateral stimuli, indicating an attention gradient. Spatial load further slowed responses at lateral locations, particularly in the left hemispace, but had little effect at midline. Verbal memory load had no (Experiment 1), or a minimal (Experiment 2) influence on reaction times. Spatial and verbal load increased switch costs between memory encoding and attention tasks relative to the no load condition. The findings show that short-term memory influences the distribution of auditory attention over space; and that the specific pattern depends on the type of information in short-term memory. PMID:29218024

Space Cooling in North America: Market Overview and Future Impacts

DOE PAGES

Baxter, Van D; Khowailed, Gannate; Sikes, Karen; ...

2015-01-01

The North American space cooling market, particularly in the United States, is experiencing shifts in regulatory regimes, population patterns, economic conditions, and consumer preferences-all catalyzed further by rapid technological innovation. Taken together these factors may result in a slight reduction in air conditioning shipments in the short term, however the longer term trends indicate a continuing increase in the number of air conditioning systems in the U.S. markets. These increases will be greatest in the warmer and more humid (e.g. higher load demand) regions. This will result in increasing pressure on the U.S. electricity supply system to meet the energymore » peak and consumption demands for building space cooling.« less

KSC ice/frost/debris assessment for space shuttle mission STS-29R

NASA Technical Reports Server (NTRS)

Stevenson, Charles G.; Katnik, Gregory N.; Higginbotham, Scott A.

1989-01-01

An ice/frost/debris assessment was conducted for Space Shuttle Mission STS-29R. Debris inspections of the flight elements and launch pad are performed before and after launch. Ice/frost conditions on the external tank are assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by an on-pad visual inspection. High speed photography is analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage. The ice/frost/debris conditions of Mission STS-29R and their effect on the Space Shuttle Program are documented.

Ice/frost/debris assessment for space shuttle mission STS-26R

NASA Technical Reports Server (NTRS)

Stevenson, Charles G.; Katnik, Gregory N.; Higginbotham, Scott A.

1988-01-01

An Ice/Frost/Debris Assessment was conducted for Space Shuttle Mission STS-26R. Debris inspections of the flight elements and launch pad are performed before and after launch. Ice/Frost conditions are assessed by use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by an on-pad visual inspection. High speed photography is viewed after launch to identify ice/debris sources and evaluate potential vehicle damage. The Ice/Frost/Debris conditions of Mission 26R and their effect on the Space Shuttle Program is documented.

Ice/frost/debris assessment for space shuttle mission STS-27R, December 2, 1988

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.; Higginbotham, Scott A.

1989-01-01

An Ice/Frost/Debris assessment was conducted for Space Shuttle Mission STS-27R. Debris inspections of the flight elements and launch pad are performed before and after launch. Ice/frost conditions are assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by an on-pad visual inspection. High speed photography is viewed after launch to identify ice/debris sources and evaluate potential vehicle damage. The Ice/Frost/Debris conditions of Mission STS-27R and their effect on the Space Shuttle Program are documented.

Structural Analysis Using Computer Based Methods

NASA Technical Reports Server (NTRS)

Dietz, Matthew R.

2013-01-01

The stiffness of a flex hose that will be used in the umbilical arms of the Space Launch Systems mobile launcher needed to be determined in order to properly qualify ground umbilical plate behavior during vehicle separation post T-0. This data is also necessary to properly size and design the motors used to retract the umbilical arms. Therefore an experiment was created to determine the stiffness of the hose. Before the test apparatus for the experiment could be built, the structure had to be analyzed to ensure it would not fail under given loading conditions. The design model was imported into the analysis software and optimized to decrease runtime while still providing accurate restlts and allow for seamless meshing. Areas exceeding the allowable stresses in the structure were located and modified before submitting the design for fabrication. In addition, a mock up of a deep space habitat and the support frame was designed and needed to be analyzed for structural integrity under different loading conditions. The load cases were provided by the customer and were applied to the structure after optimizing the geometry. Once again, weak points in the structure were located and recommended design changes were made to the customer and the process was repeated until the load conditions were met without exceeding the allowable stresses. After the stresses met the required factors of safety the designs were released for fabrication.

Impact of Infiltration and Ventilation on Measured Space Conditioning Energy and Moisture Levels in the Hot-Humid Climate, Cocoa, Florida (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

Air infiltration and ventilation in residential buildings is a very large part of the heating loads, but empirical data regarding the impact on space cooling has been lacking. Moreover, there has been little data on how building tightness might relate to building interior moisture levels in homes in a hot and humid climate. To address this need, BA-PIRC has conducted research to assess the moisture and cooling load impacts of airtightness and mechanical ventilation in two identical laboratory homes in the hot-humid climate over the cooling season.

Technology Solutions Case Study: Impact of Infiltration and Ventilation on Measured Space Conditioning Energy and Moisture Levels in the Hot-Humid Climate

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Air infiltration and ventilation in residential buildings is a very large part of the heating loads, but empirical data regarding the impact on space cooling has been lacking. Moreover, there has been little data on how building tightness might relate to building interior moisture levels in homes in a hot and humid climate. To address this need, BA-PIRC conducted research to assess the moisture and cooling load impacts of airtightness and mechanical ventilation in two identical laboratory homes in the hot-humid climate over the cooling season.

MLP-1 on Crawler Transporter 2 (CT-2)

NASA Image and Video Library

2017-03-22

NASA's upgraded crawler-transporter 2 (CT-2), carrying mobile launcher platform 1, moves slowly along the crawlerway at the agency's Kennedy Space Center in Florida. The crawler's upgrades and modifications will be monitored and tested under loaded conditions during its travel to the crawlerway Pad A/B split and back to the crawler yard to confirm it is ready to support the load of the mobile launcher carrying the Space Launch System with Orion atop for the first test flight, Exploration Mission 1. The Ground Systems Development and Operations Program at Kennedy is managing upgrades to the crawler.

14 CFR 27.479 - Level landing conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Level landing conditions. 27.479 Section 27... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.479 Level landing..., the rotorcraft is assumed to be in each of the following level landing attitudes: (1) An attitude in...

14 CFR 25.529 - Hull and main float landing conditions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Hull and main float landing conditions. 25... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Water Loads § 25.529 Hull and main.... (b) Unsymmetrical landing for hull and single float seaplanes. Unsymmetrical step, bow, and stern...

14 CFR 25.415 - Ground gust conditions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ground gust conditions. 25.415 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Control Surface and System Loads § 25.415 Ground... ground gusts and taxiing downwind: (1) The control system between the stops nearest the surfaces and the...

14 CFR 25.415 - Ground gust conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ground gust conditions. 25.415 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Control Surface and System Loads § 25.415 Ground... ground gusts and taxiing downwind: (1) The control system between the stops nearest the surfaces and the...

Preliminary 2-D shell analysis of the space shuttle solid rocket boosters

NASA Technical Reports Server (NTRS)

Knight, Norman F., Jr.; Gillian, Ronnie E.; Nemeth, Michael P.

1987-01-01

A two-dimensional shell model of an entire solid rocket booster (SRB) has been developed using the STAGSC-1 computer code and executed on the Ames CRAY computer. The purpose of these analyses is to calculate the overall deflection and stress distributions for the SRB when subjected to mechanical loads corresponding to critical times during the launch sequence. The mechanical loading conditions for the full SRB arise from the external tank (ET) attachment points, the solid rocket motor (SRM) pressure load, and the SRB hold down posts. The ET strut loads vary with time after the Space Shuttle main engine (SSME) ignition. The SRM internal pressure varies axially by approximately 100 psi. Static analyses of the full SRB are performed using a snapshot picture of the loads. The field and factory joints are modeled by using equivalent stiffness joints instead of detailed models of the joint. As such, local joint behavior cannot be obtained from this global model.

Verification of the Multi-Axial, Temperature and Time Dependent (MATT) Failure Criterion

NASA Technical Reports Server (NTRS)

Richardson, David E.; Macon, David J.

2005-01-01

An extensive test and analytical effort has been completed by the Space Shuttle's Reusable Solid Rocket Motor (KSKM) nozzle program to characterize the failure behavior of two epoxy adhesives (TIGA 321 and EA946). As part of this effort, a general failure model, the "Multi-Axial, Temperature, and Time Dependent" or MATT failure criterion was developed. In the initial development of this failure criterion, tests were conducted to provide validation of the theory under a wide range of test conditions. The purpose of this paper is to present additional verification of the MATT failure criterion, under new loading conditions for the adhesives TIGA 321 and EA946. In many cases, the loading conditions involve an extrapolation from the conditions under which the material models were originally developed. Testing was conducted using three loading conditions: multi-axial tension, torsional shear, and non-uniform tension in a bondline condition. Tests were conducted at constant and cyclic loading rates ranging over four orders of magnitude. Tests were conducted under environmental conditions of primary interest to the RSRM program. The temperature range was not extreme, but the loading ranges were extreme (varying by four orders of magnitude). It should be noted that the testing was conducted at temperatures below the glass transition temperature of the TIGA 321 adhesive. However for the EA946, the testing was conducted at temperatures that bracketed the glass transition temperature.

The Surface Layer Mechanical Condition and Residual Stress Forming Model in Surface Plastic Deformation Process with the Hardened Body Effect Consideration

NASA Astrophysics Data System (ADS)

Mahalov, M. S.; Blumenstein, V. Yu

2017-10-01

The mechanical condition and residual stresses (RS) research and computational algorithms creation in complex types of loading on the product lifecycle stages relevance is shown. The mechanical state and RS forming finite element model at surface plastic deformation strengthening machining, including technological inheritance effect, is presented. A model feature is the production previous stages obtained transformation properties consideration, as well as these properties evolution during metal particles displacement through the deformation space in the present loading step.

Francis-99: Transient CFD simulation of load changes and turbine shutdown in a model sized high-head Francis turbine

NASA Astrophysics Data System (ADS)

Mössinger, Peter; Jester-Zürker, Roland; Jung, Alexander

2017-01-01

With increasing requirements for hydropower plant operation due to intermittent renewable energy sources like wind and solar, numerical simulations of transient operations in hydraulic turbo machines become more important. As a continuation of the work performed for the first workshop which covered three steady operating conditions, in the present paper load changes and a shutdown procedure are investigated. The findings of previous studies are used to create a 360° model and compare measurements with simulation results for the operating points part load, high load and best efficiency. A mesh motion procedure is introduced, allowing to represent moving guide vanes for load changes from best efficiency to part load and high load. Additionally an automated re-mesh procedure is added for turbine shutdown to ensure reliable mesh quality during guide vane closing. All three transient operations are compared to PIV velocity measurements in the draft tube and pressure signals in the vaneless space. Simulation results of axial velocity distributions for all three steady operation points, during both load changes and for the shutdown correlated well with the measurement. An offset at vaneless space pressure is found to be a result of guide vane corrections for the simulation to ensure similar velocity fields. Short-time Fourier transformation indicating increasing amplitudes and frequencies at speed-no load conditions. Further studies will discuss the already measured start-up procedure and investigate the necessity to consider the hydraulic system dynamics upstream of the turbine by means of a 1D3D coupling between the 3D flow field and a 1D system model.

The propagation and backscattering of soliton-like pulses in a chain of quartz beads and related problems. (I). Propagation

NASA Astrophysics Data System (ADS)

Manciu, Marian; Sen, Surajit; Hurd, Alan J.

1999-12-01

We confirm that for vanishingly small loading and large impact condition, it may be possible to generate solitons in a chain of grains that are characterized by Hertzian contacts. For uniform or progressive loading conditions throughout the chain, one generates soft-solitons which are weakly dispersive in space and time. Under conditions of weak impact, one generates acoustic pulses through the chain. We describe the displacements, velocities and accelerations suffered by the individual grains when subjected to solitons, soft-solitons and acoustic pulses and describe the effects of restitution on the propagating pulse.

Sediment load from major rivers into Puget Sound and its adjacent waters

USGS Publications Warehouse

Czuba, Jonathan A.; Magirl, Christopher S.; Czuba, Christiana R.; Grossman, Eric E.; Curran, Christopher A.; Gendaszek, Andrew S.; Dinicola, Richard S.

2011-01-01

Each year, an estimated load of 6.5 million tons of sediment is transported by rivers to Puget Sound and its adjacent waters—enough to cover a football field to the height of six Space Needles. This estimated load is highly uncertain because sediment studies and available sediment-load data are sparse and historically limited to specific rivers, short time frames, and a narrow range of hydrologic conditions. The largest sediment loads are carried by rivers with glaciated volcanoes in their headwaters. Research suggests 70 percent of the sediment load delivered to Puget Sound is from rivers and 30 percent is from shoreline erosion, but the magnitude of specific contributions is highly uncertain. Most of a river's sediment load occurs during floods.

Cryogenic Evaluation of an Advanced DC/DC Converter Module for Deep Space Applications

NASA Technical Reports Server (NTRS)

Elbuluk, Malik E.; Hammoud, Ahmad; Gerber, Scott S.; Patterson, Richard

2003-01-01

DC/DC converters are widely used in power management, conditioning, and control of space power systems. Deep space applications require electronics that withstand cryogenic temperature and meet a stringent radiation tolerance. In this work, the performance of an advanced, radiation-hardened (rad-hard) commercial DC/DC converter module was investigated at cryogenic temperatures. The converter was investigated in terms of its steady state and dynamic operations. The output voltage regulation, efficiency, terminal current ripple characteristics, and output voltage response to load changes were determined in the temperature range of 20 to -140 C. These parameters were obtained at various load levels and at different input voltages. The experimental procedures along with the results obtained on the investigated converter are presented and discussed.

Cyclic load magnitude is a risk factor for a cumulative lower back disorder.

PubMed

Le, Peter; Solomonow, Moshe; Zhou, Bing-He; Lu, Yun; Patel, Vikas

2007-04-01

Epidemiological data suggest that high loads lifted by workers engaged in static and cyclic daily activities may be a risk factor for low back disorder. Our previous research provided physiological and biomechanical validation of the epidemiological data for static load conditions. The objective of this report was to provide physiological and biomechanical experimental validation to the epidemiological data in cyclic (repetitive) load conditions. Three groups of in vivo feline models were subjected to 3 cyclic load levels in a series of 6 periods of 10 minutes of work spaced by 10 minutes of rest followed by 7 hours of rest. Multifidus electromyography (EMG) and lumbar displacement were statistically analyzed after processing. Delayed muscular hyperexcitability was observed only in moderate (40 N) and high (60 N) loads (P<0.0001) but was absent in low (20 N) loads. The magnitude of the delayed hyperexcitability was found to be higher (P<0.0001) in the high (60 N) loads compared with the moderate (40 N) loads. Exposure to moderate and high loads in cyclic (repetitive) work results in an acute neuromuscular disorder indicative of soft tissue inflammation that may become chronic with further exposure.

Strategy Guideline: Compact Air Distribution Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burdick, A.

2013-06-01

This Strategy Guideline discusses the benefits and challenges of using a compact air distribution system to handle the reduced loads and reduced air volume needed to condition the space within an energy efficient home. Traditional systems sized by 'rule of thumb' (i.e., 1 ton of cooling per 400 ft2 of floor space) that 'wash' the exterior walls with conditioned air from floor registers cannot provide appropriate air mixing and moisture removal in low-load homes. A compact air distribution system locates the HVAC equipment centrally with shorter ducts run to interior walls, and ceiling supply outlets throw the air toward themore » exterior walls along the ceiling plane; alternatively, high sidewall supply outlets throw the air toward the exterior walls. Potential drawbacks include resistance from installing contractors or code officials who are unfamiliar with compact air distribution systems, as well as a lack of availability of low-cost high sidewall or ceiling supply outlets to meet the low air volumes with good throw characteristics. The decision criteria for a compact air distribution system must be determined early in the whole-house design process, considering both supply and return air design. However, careful installation of a compact air distribution system can result in lower material costs from smaller equipment, shorter duct runs, and fewer outlets; increased installation efficiencies, including ease of fitting the system into conditioned space; lower loads on a better balanced HVAC system, and overall improved energy efficiency of the home.« less

Solar-energy-system performance-evaluation update: El Toro Library, El Toro, California, December 1981-August 1982

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kendall, P.W.

The El Toro Library is a one-story facility that contains 10,000 square feet of floor area. The solar energy system was designed to provide 97% of the space heating load and 60% of the space cooling load. The solar energy system incorporates 82 panels with a gross area of 1427 square feet of evacuated tubular glass collectors (TC-100) manufactured by General Electric. The storage tank is a 1500-gallon insulated steel tank which is located outside, above ground level. The space heating subsystem uses solar energy from storage and/or thermal energy from the natural-gas-fired boiler. The space cooling subsystem uses anmore » absorption chiller to provide chilled water to the air-handling unit. As compared to the previous year, performance over the nine-month monitoring period was improved, based on overall solar contribution to the load. When compared to design values, the overall performance was poor. Overall solar fraction was an estimated 22% of the 220 million Btu system load. A total of 122 million Btu of solar energy was used by the space conditioning system. Auxiliary fossil fuel consumption was 608 million Btu, or 595,800 cubic feet of natural gas. Auxiliary thermal energy was a measured 68% of the auxiliary fossil fuel consumed. The solar savings ratio, a measure of the solar contribution to the load discounted by solar operating energy, averaged 19% during the analysis period. The previous year, the solar savings ratio was 16%.« less

Evaluation of load tracks and wear of two sets of bearings from space shuttle main engine high pressure oxygen turbopumps

NASA Technical Reports Server (NTRS)

Kannel, J. W.; Dufrane, K. F.

1985-01-01

Bearings supporting the rotor in the High Pressure Oxygen Turbopump (HPOTP) were examined. The No. 1 bearings from both units were in good condition and had successfully completed 5000 seconds of operation. The No. 2 bearings, which were in service the same length of time, were significantly degraded in the form of ball wear, race pitting, and damage from high axial loads. The No. 3 and 4 bearings were in generally acceptable condition. The general conclusion from the examinations was that improved cooling on the No. 2 bearings and further improvements in controlling axial and radial load would likely result in the HPOTP meeting the qualification test results.

Geometrically Nonlinear Finite Element Analysis of a Composite Space Reflector

NASA Technical Reports Server (NTRS)

Lee, Kee-Joo; Leet, Sung W.; Clark, Greg; Broduer, Steve (Technical Monitor)

2001-01-01

Lightweight aerospace structures, such as low areal density composite space reflectors, are highly flexible and may undergo large deflection under applied loading, especially during the launch phase. Accordingly, geometrically nonlinear analysis that takes into account the effect of finite rotation may be needed to determine the deformed shape for a clearance check and the stress and strain state to ensure structural integrity. In this study, deformation of the space reflector is determined under static conditions using a geometrically nonlinear solid shell finite element model. For the solid shell element formulation, the kinematics of deformation is described by six variables that are purely vector components. Because rotational angles are not used, this approach is free of the limitations of small angle increments. This also allows easy connections between substructures and large load increments with respect to the conventional shell formulation using rotational parameters. Geometrically nonlinear analyses were carried out for three cases of static point loads applied at selected points. A chart shows results for a case when the load is applied at the center point of the reflector dish. The computed results capture the nonlinear behavior of the composite reflector as the applied load increases. Also, they are in good agreement with the data obtained by experiments.

KSC ice/frost/debris assessment for Space Shuttle Mission STS-30R

NASA Technical Reports Server (NTRS)

Stevenson, Charles G.; Katnik, Gregory N.; Higginbotham, Scott A.

1989-01-01

An ice/frost/debris assessment was conducted for Space Shuttle Mission STS-30R. Debris inspections of the flight elements and launch pad are performed before and after launch. Ice/frost conditions on the external tank are assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by an on-pad visual inspection. High speed photography is analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage. The ice/frost/debris conditions of Mission STS-30R and their overall effect on the Space Shuttle Program is documented.

Stability of large DC power systems using switching converters, with application to the international space station

NASA Technical Reports Server (NTRS)

Manners, B.; Gholdston, E. W.; Karimi, K.; Lee, F. C.; Rajagopalan, J.; Panov, Y.

1996-01-01

As space direct current (dc) power systems continue to grow in size, switching power converters are playing an ever larger role in power conditioning and control. When designing a large dc system using power converters of this type, special attention must be placed on the electrical stability of the system and of the individual loads on the system. In the design of the electric power system (EPS) of the International Space Station (ISS), the National Aeronautics and Space Administration (NASA) and its contractor team led by Boeing Defense & Space Group has placed a great deal of emphasis on designing for system and load stability. To achieve this goal, the team has expended considerable effort deriving a dear concept on defining system stability in both a general sense and specifically with respect to the space station. The ISS power system presents numerous challenges with respect to system stability, such as high power, complex sources and undefined loads. To complicate these issues, source and load components have been designed in parallel by three major subcontractors (Boeing, Rocketdyne, and McDonnell Douglas) with interfaces to both sources and loads being designed in different countries (Russia, Japan, Canada, Europe, etc.). These issues, coupled with the program goal of limiting costs, have proven a significant challenge to the program. As a result, the program has derived an impedance specification approach for system stability. This approach is based on the significant relationship between source and load impedances and the effect of this relationship on system stability. This approach is limited in its applicability by the theoretical and practical limits on component designs as presented by each system segment. As a result, the overall approach to system stability implemented by the ISS program consists of specific hardware requirements coupled with extensive system analysis and hardware testing. Following this approach, the ISS program plans to begin construction of the world's largest orbiting power system in 1997.

Non-Static error tracking control for near space airship loading platform

NASA Astrophysics Data System (ADS)

Ni, Ming; Tao, Fei; Yang, Jiandong

2018-01-01

A control scheme based on internal model with non-static error is presented against the uncertainty of the near space airship loading platform system. The uncertainty in the tracking table is represented as interval variations in stability and control derivatives. By formulating the tracking problem of the uncertainty system as a robust state feedback stabilization problem of an augmented system, sufficient condition for the existence of robust tracking controller is derived in the form of linear matrix inequality (LMI). Finally, simulation results show that the new method not only has better anti-jamming performance, but also improves the dynamic performance of the high-order systems.

MLP-1 on Crawler Transporter 2 (CT-2)

NASA Image and Video Library

2017-03-22

Ground support technicians walk alongside NASA's upgraded crawler-transporter 2 (CT-2), carrying mobile launcher platform 1, as it slowly travels on the crawlerway at the agency's Kennedy Space Center in Florida. The crawler's upgrades and modifications will be monitored and tested under loaded conditions during its travel to the crawlerway Pad A/B split and back to the crawler yard to confirm it is ready to support the load of the mobile launcher carrying the Space Launch System with Orion atop for the first test flight, Exploration Mission 1. The Ground Systems Development and Operations Program at Kennedy is managing upgrades to the crawler.

In situ experimental study of carbon monoxide generation by gasoline-powered electric generator in an enclosed space.

PubMed

Wang, Liangzhu; Emmerich, Steven J; Persily, Andrew K

2010-12-01

On the basis of currently available data, approximately 97% of generator-related carbon monoxide (CO) fatalities are caused by operating currently marketed, carbureted spark-ignited gasoline-powered generators (not equipped with emission controls) in enclosed spaces. To better understand and to reduce the occurrence of these fatalities, research is needed to quantify CO generation rates, develop and test CO emission control devices, and evaluate CO transport and exposure when operating a generator in an enclosed space. As a first step in these efforts, this paper presents measured CO generation rates from a generator without any emission control devices operating in an enclosed space under real weather conditions. This study expands on previously published information from the U.S. Consumer Product Safety Commission. Thirteen separate tests were conducted under different weather conditions at half and full generator load settings. It was found that the CO level in the shed reached a maximum value of 29,300 +/- 580 mg/m3, whereas the oxygen (O2) was depleted to a minimum level of 16.2 +/- 0.02% by volume. For the test conditions of real weather and generator operation, the CO generation and the O2 consumption could be expressed as time-averaged generation/consumption rates. It was also found that the CO generation and O2 consumption rates can be correlated to the O2 levels in the space and the actual load output from the generator. These correlations are shown to agree well with the measurements.

Further Investigations of Control Surface Seals for the X-38 Re-Entry Vehicle

NASA Technical Reports Server (NTRS)

Dunlap, Patrick H., Jr.; Steinetz, Bruce M.; Curry, Donald M.; Newquist, Charles W.; Verzemnieks, Juris

2001-01-01

NASA is currently developing the X-38 vehicle that will be used to demonstrate the technologies required for a potential crew return vehicle (CRV) for the International Space Station. This vehicle would serve both as an ambulance for medical emergencies and as an evacuation vehicle for the Space Station. Control surfaces on the X-38 (body flaps and rudder/fin assemblies) require high temperature seals to limit hot gas ingestion and transfer of heat to underlying low-temperature structures to prevent over-temperature of these structures and possible loss of the vehicle. NASAs Johnson Space Center (JSC) and Glenn Research Center (GRC) are working together to develop and evaluate seals for these control surfaces. This paper presents results for compression. flow, scrub, and arc jet tests conducted on the baseline X-38 rudder/fin seal design. Room temperature seal compression tests were performed at low compression levels to determine load versus linear compression, preload. contact area, stiffness. and resiliency characteristics under low load conditions. For all compression levels that were tested, unit loads and contact pressures for the seals were below the 5 lb/in. and 10 psi limits required to limit the loads on the adjoining Shuttle thermal tiles that the seals will contact. Flow rates through an unloaded (i.e. 0% compression) double arrangement were twice those of a double seal compressed to the 20% design compression level. The seals survived an ambient temperature 1000 cycle scrub test over relatively rough Shuttle tile surfaces. The seals were able to disengage and re-engage the edges of the rub surface tiles while being scrubbed over them. Arc jet tests were performed to experimentally determine anticipated seal temperatures for representative flow boundary conditions (pressures and temperatures) under simulated vehicle re-entry conditions. Installation of a single seat in the gap of the test fixture caused a large temperature drop (1710 F) across the seal location as compared to an open gap condition (140 F) confirming the need for seals in the rudder/fin gap location. The seal acted as an effective thermal barrier limiting heat convection through the seal gap and minimizing temperature increases downstream of the seal during maximum heating conditions.

Meso and micro-scale response of post carbon removal nitrifying MBBR biofilm across carrier type and loading.

PubMed

Young, Bradley; Banihashemi, Bahman; Forrest, Daina; Kennedy, Kevin; Stintzi, Alain; Delatolla, Robert

2016-03-15

This study investigates the effects of three specific moving bed biofilm reactor (MBBR) carrier types and two surface area loading rates on biofilm thickness, morphology and bacterial community structure of post carbon removal nitrifying MBBR systems along with the effects of carrier type and loading on ammonia removal rates and effluent solids settleability. The meso and micro analyses show that the AOB kinetics vary based on loading condition, but irrespective of carrier type. The meso-scale response to increases in loading was shown to be an increase in biofilm thickness with higher surface area carriers being more inclined to develop and maintain thicker biofilms. The pore spaces of these higher surface area to volume carriers also demonstrated the potential to become clogged at higher loading conditions. Although the biofilm thickness increased during higher loading conditions, the relative percentages of both the embedded viable and non-viable cells at high and conventional loading conditions remained stable; indicating that the reduced ammonia removal kinetics observed during carrier clogging events is likely due to the observed reduction in the surface area of the attached biofilm. Microbial community analyses demonstrated that the dominant ammonia oxidizing bacteria for all carriers is Nitrosomonas while the dominant nitrite oxidizing bacteria is Nitrospira. The research showed that filamentous species were abundant under high loading conditions, which likely resulted in the observed reduction in effluent solids settleability at high loading conditions as opposed to conventional loading conditions. Although the settleability of the effluent solids was correlated to increases in abundances of filamentous organisms in the biofilm, analyzed using next generation sequencing, the ammonia removal rate was not shown to be directly correlated to specific meso or micro-scale characteristics. Instead post carbon removal MBBR ammonia removal kinetics were shown to be related to the viable AOB cell coverage of the carriers; which was calculated by normalizing the surface area removal rate by the biofilm thickness, the bacterial percent abundance of ammonia oxidizing bacteria and the percentage of viable cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

Probabilistic Risk Assessment for Astronaut Post Flight Bone Fracture

NASA Technical Reports Server (NTRS)

Lewandowski, Beth; Myers, Jerry; Licata, Angelo

2015-01-01

Introduction: Space flight potentially reduces the loading that bone can resist before fracture. This reduction in bone integrity may result from a combination of factors, the most common reported as reduction in astronaut BMD. Although evaluating the condition of bones continues to be a critical aspect of understanding space flight fracture risk, defining the loading regime, whether on earth, in microgravity, or in reduced gravity on a planetary surface, remains a significant component of estimating the fracture risks to astronauts. This presentation summarizes the concepts, development, and application of NASA's Bone Fracture Risk Module (BFxRM) to understanding pre-, post, and in mission astronaut bone fracture risk. The overview includes an assessment of contributing factors utilized in the BFxRM and illustrates how new information, such as biomechanics of space suit design or better understanding of post flight activities may influence astronaut fracture risk. Opportunities for the bone mineral research community to contribute to future model development are also discussed. Methods: To investigate the conditions in which spaceflight induced changes to bone plays a critical role in post-flight fracture probability, we implement a modified version of the NASA Bone Fracture Risk Model (BFxRM). Modifications included incorporation of variations in physiological characteristics, post-flight recovery rate, and variations in lateral fall conditions within the probabilistic simulation parameter space. The modeled fracture probability estimates for different loading scenarios at preflight and at 0 and 365 days post-flight time periods are compared. Results: For simple lateral side falls, mean post-flight fracture probability is elevated over mean preflight fracture probability due to spaceflight induced BMD loss and is not fully recovered at 365 days post-flight. In the case of more energetic falls, such as from elevated heights or with the addition of lateral movement, the contribution of space flight quality changes is much less clear, indicating more granular assessments, such as Finite Element modeling, may be needed to further assess the risks in these scenarios.

Evaluating Moisture Control of Variable-Capacity Heat Pumps in Mechanically Ventilated, Low-Load Homes in Climate Zone 2A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Eric; Withers, Chuck; McIlvaine, Janet

Low-load homes can present a challenge when selecting appropriate space-conditioning equipment. Conventional, fixed-capacity heating and cooling equipment is often oversized for small homes, causing increased first costs and operating costs. This report evaluates the performance of variable-capacity comfort systems, with a focus on inverter-driven, variable-capacity systems, as well as proposed system enhancements.

Sphere launcher

NASA Technical Reports Server (NTRS)

Reed, W. B.

1972-01-01

The sphere launcher was designed to eject a 200 lb, 15 in. diameter sphere from a space vehicle or missile, at a velocity of 58 ft/sec without imparting excessive lateral loads to the vehicle. This launching is accomplished with the vehicle operating in vacuum conditions and under a 9 g acceleration. Two principal elements are used: a high thrust, short burn time rocket motor and two snubbers for reducing the lateral loads to acceptable limits.

Space Heating Load Estimation Procedure for CHP Systems sizing

NASA Astrophysics Data System (ADS)

Vocale, P.; Pagliarini, G.; Rainieri, S.

2015-11-01

Due to its environmental and energy benefits, the Combined Heat and Power (CHP) represents certainly an important measure to improve energy efficiency of buildings. Since the energy performance of the CHP systems strongly depends on the fraction of the useful cogenerated heat (i.e. the cogenerated heat that is actually used to meet building thermal demand), in building applications of CHP, it is necessary to know the space heating and cooling loads profile to optimise the system efficiency. When the heating load profile is unknown or difficult to calculate with a sufficient accuracy, as may occur for existing buildings, it can be estimated from the cumulated energy uses by adopting the loads estimation procedure (h-LEP). With the aim to evaluate the useful fraction of the cogenerated heat for different operating conditions in terms of buildings characteristics, weather data and system capacity, the h-LEP is here implemented with a single climate variable: the hourly average dry- bulb temperature. The proposed procedure have been validated resorting to the TRNSYS simulation tool. The results, obtained by considering a building for hospital use, reveal that the useful fraction of the cogenerated heat can be estimated with an average accuracy of ± 3%, within the range of operative conditions considered in the present study.

Methods of body orientation in space in the absence of support under weightless conditions

NASA Technical Reports Server (NTRS)

Yeremin, A. V.; Stepantsov, V. I.; Chekidra, I. F.; Borisenko, I. P.; Kolosov, I. A.

1975-01-01

The experience accumulated in training subjects in methods of body orientation in space indicates the necessity of clear planning of the training process. After theoretical familiarization with the principles of body orientation in space and reviewing training films, practical mastery of the body orientation methods begins with working out of the individual elements on the Zhukovskiy stool. Then, the correctness and sequence of movements are carefully mastered in water, and the motor skills are then reinforced under time deficit conditions, on the vaulting bars, trampolines, and, in the concluding stage of training, the methods of orienting the body in space in weightlessness are worked out in laboratory-aircraft, with and without the spacesuit and with and without a load.

Structural Evaluation of a Space Shuttle Main Engine (SSME) High Pressure Fuel Turbopump Turbine Blade

NASA Technical Reports Server (NTRS)

Abdul-Aziz, Ali

1996-01-01

Thermal and structural finite-element analyses were performed on the first high pressure fuel turbopump turbine blade of the space shuttle main engine (SSME). A two-dimensional (2-D) finite-element model of the blade and firtree disk attachment was analyzed using the general purpose MARC (finite-element) code. The loading history applied is a typical test stand engine cycle mission, which consists of a startup condition with two thermal spikes, a steady state and a shutdown transient. The blade material is a directionally solidified (DS) Mar-M 246 alloy, the blade rotor is forged with waspalloy material. Thermal responses under steady-state and transient conditions were calculated. The stresses and strains under the influence of mechanical and thermal loadings were also determined. The critical regions that exhibited high stresses and severe localized plastic deformation were the blade-rotor gaps.

Benchmark solution for vibrations from a moving point source in a tunnel embedded in a half-space

NASA Astrophysics Data System (ADS)

Yuan, Zonghao; Boström, Anders; Cai, Yuanqiang

2017-01-01

A closed-form semi-analytical solution for the vibrations due to a moving point load in a tunnel embedded in a half-space is given in this paper. The tunnel is modelled as an elastic hollow cylinder and the ground surrounding the tunnel as a linear viscoelastic material. The total wave field in the half-space with a cylindrical hole is represented by outgoing cylindrical waves and down-going plane waves. To apply the boundary conditions on the ground surface and at the tunnel-soil interface, the transformation properties between the plane and cylindrical wave functions are employed. The proposed solution can predict the ground vibration from an underground railway tunnel of circular cross-section with a reasonable computational effort and can serve as a benchmark solution for other computational methods. Numerical results for the ground vibrations on the free surface due to a moving constant load and a moving harmonic load applied at the tunnel invert are presented for different load velocities and excitation frequencies. It is found that Rayleigh waves play an important role in the ground vibrations from a shallow tunnel.

An IBEM solution to the scattering of plane SH-waves by a lined tunnel in elastic wedge space

NASA Astrophysics Data System (ADS)

Liu, Zhongxian; Liu, Lei

2015-02-01

The indirect boundary element method (IBEM) is developed to solve the scattering of plane SH-waves by a lined tunnel in elastic wedge space. According to the theory of single-layer potential, the scattered-wave field can be constructed by applying virtual uniform loads on the surface of lined tunnel and the nearby wedge surface. The densities of virtual loads can be solved by establishing equations through the continuity conditions on the interface and zero-traction conditions on free surfaces. The total wave field is obtained by the superposition of free field and scattered-wave field in elastic wedge space. Numerical results indicate that the IBEM can solve the diffraction of elastic wave in elastic wedge space accurately and efficiently. The wave motion feature strongly depends on the wedge angle, the angle of incidence, incident frequency, the location of lined tunnel, and material parameters. The waves interference and amplification effect around the tunnel in wedge space is more significant, causing the dynamic stress concentration factor on rigid tunnel and the displacement amplitude of flexible tunnel up to 50.0 and 17.0, respectively, more than double that of the case of half-space. Hence, considerable attention should be paid to seismic resistant or anti-explosion design of the tunnel built on a slope or hillside.

Low-Load Space Conditioning Needs Assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puttagunta, Srikanth

Heating, ventilating, and air-conditioning (HVAC) equipment must be right-sized to ensure energy performance and comfort. With limited low-load options in the HVAC market, many new-construction housing units are being fitted with oversized equipment that creates system efficiency, comfort, and cost penalties. To bridge the gap between currently available HVAC equipment that is oversized or inefficient and the rising demand for low-load HVAC equipment in the marketplace, HVAC equipment manufacturers need to be fully aware of the needs of the multifamily building and attached single-family (duplex and townhouse) home market. Over the past decade, Steven Winter Associates, Inc. (SWA) has providedmore » certification and consulting services for hundreds of housing projects and has accrued a large pool of data that describe multifamily and attached single-family home characteristics. The U.S. Department of Energy’s Building America research team Consortium for Advanced Residential Buildings (CARB) compiled and analyzed these data to outline the characteristics of low-load dwellings such as the heating and cooling design loads.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poerschke, Andrew; Rudd, Armin

This report investigates the feasibility of using a home-run manifold small-diameter duct system to provide space-conditioning air to individual thermal zones in a low-load home. This compact layout allows duct systems to easily be brought within conditioned space via interior partition walls. Centrally locating the air handling unit in the house significantly reduces duct lengths. The plenum box is designed so that each connected duct receives a similar amount of airflow—regardless of its position on the box. Furthermore, within a reasonable set of length restrictions each duct continues to receive similar airflow.

Parallel processing methods for space based power systems

NASA Technical Reports Server (NTRS)

Berry, F. C.

1993-01-01

This report presents a method for doing load-flow analysis of a power system by using a decomposition approach. The power system for the Space Shuttle is used as a basis to build a model for the load-flow analysis. To test the decomposition method for doing load-flow analysis, simulations were performed on power systems of 16, 25, 34, 43, 52, 61, 70, and 79 nodes. Each of the power systems was divided into subsystems and simulated under steady-state conditions. The results from these tests have been found to be as accurate as tests performed using a standard serial simulator. The division of the power systems into different subsystems was done by assigning a processor to each area. There were 13 transputers available, therefore, up to 13 different subsystems could be simulated at the same time. This report has preliminary results for a load-flow analysis using a decomposition principal. The report shows that the decomposition algorithm for load-flow analysis is well suited for parallel processing and provides increases in the speed of execution.

14 CFR 23.407 - Trim tab effects.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Trim tab effects. 23.407 Section 23.407... Loads § 23.407 Trim tab effects. The effects of trim tabs on the control surface design conditions must... deflections must correspond to the maximum degree of “out of trim” expected at the speed for the condition...

14 CFR 23.407 - Trim tab effects.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Trim tab effects. 23.407 Section 23.407... Loads § 23.407 Trim tab effects. The effects of trim tabs on the control surface design conditions must... deflections must correspond to the maximum degree of “out of trim” expected at the speed for the condition...

Portable Load Measurement Device for Use During ARED Exercise on ISS

NASA Technical Reports Server (NTRS)

Hanson, A.; Peters, B.; Caldwell, E.; Sinka, J.; Kreutzburg, G.; Ploutz-Snyder, L.

2014-01-01

The Advanced Resistive Exercise Device (ARED) (Fig.1) is unique countermeasure hardware available to crewmembers aboard the International Space Station (ISS) used for resistance exercise training to protect against bone and muscle loss during long duration space missions. ARED instrumentation system was designed to measure and record exercise load data, but: - Reliably accurate data has not been available due to a defective force platform. - No ARED data has been recorded since mid-2011 due to failures in the instrumentation power system. ARED load data supports on-going HRP funded research, and is available to extramural researchers through LSDA-Repository. Astronaut Strength, Conditioning, and Rehabilitation specialists (ASCRs) use ARED data to track training progress and advance exercise prescriptions. ARED load data is necessary to fulfill medical requirements. HRP directed task intends to reduce to program risk (HRP IRMA Risk 1735), and evaluate the XSENS ForceShoeTM as a means of obtaining ARED load data during exercise sessions. The XSENS ForceShoes"TM" will fly as a hardware demonstration to ISS in May 2014 (39S). Additional portable load monitoring devices (PLMDs) are under evaluation in the ExPC Lab. PLMDs are favored over platform redesign as they support future exploration needs.

Mapping HIV community viral load: space, power and the government of bodies

PubMed Central

Gagnon, Marilou; Guta, Adrian

2012-01-01

HIV plasma viral load testing has become more than just a clinical tool to monitor treatment response at the individual level. Increasingly, individual HIV plasma viral load testing is being reported to public health agencies and is used to inform epidemiological surveillance and monitor the presence of the virus collectively using techniques to measure ‘community viral load’. This article seeks to formulate a critique and propose a novel way of theorizing community viral load. Based on the salient work of Michel Foucault, especially the governmentality literature, this article critically examines the use of community viral load as a new strategy of government. Drawing also on the work of Miller and Rose, this article explores the deployment of ‘community’ through the re-configuration of space, the problematization of viral concentrations in specific microlocales, and the government (in the Foucauldian sense) of specific bodies which are seen as ‘risky’, dangerous and therefore, in need of attention. It also examines community viral load as a necessary precondition — forming the ‘conditions of possibility’ — for the recent shift to high impact prevention tactics that are being scaled up across North America. PMID:23060688

Foot Forces during Treadmill Exercise on the International Space Station

NASA Technical Reports Server (NTRS)

Cavanagh, Peter R.; Rice, Andrea J.; Maender, Christian C.; Gopalakrishnan, Raghavan; Genc, Kerim O.; Kuklis, Matthew

2006-01-01

Exercise has been the primary countermeasure to combat musculoskeletal changes during the approximately 6 month missions to the International Space Station (ISS). However, these countermeasures have not been successful in preventing loss of bone mineral density in the spine and hip of astronauts. We examined lower extremity loading during typical bouts of on-orbit exercise performed by 4 ISS crew members on the ISS treadmill (TVIS) and during locomotor activities on earth (1g). In-shoe forces were monitored at 128Hz using force-measuring insoles placed inside the shoes of the exercising crewmember, stored temporarily on Flash cards, and down-linked via satellite for analysis. Custom software extracted peak forces from up to 30 minutes of locomotor activity. All on-orbit loading conditions for walking and running resulted in peak forces and impact loading rates that were significantly less than those measured in 1g. Typical single leg loads on-orbit in walking and running were 0.860 plus or minus 0.04 body weights (BW) and 1.339 plus or minus 0.07 BW compared to 1.2 plus or minus 0.036 BW and 2.36 plus or minus 0.07 BW in 1g BW respectively. These results indicate that typical exercise on the ISS treadmill does not generate 1g-like loading conditions. This may be partly responsible for the loss of bone mineral density that has been observed in these and other crew members. Since on-orbit treadmill exercise requires a restraining load to return the crew member to the treadmill surface, more studies are required to enable comfortable full body weight loading to be applied.

Environmental Effects on Long Term Displacement Data of Woven Fabric Webbings Under Constant Load for Inflatable Structures

NASA Technical Reports Server (NTRS)

Kenner, WInfred S.; Jones, Thomas C.; Doggett, William R.; Duncan, Quinton; Plant, James

2015-01-01

An experimental study of the effects of environmental temperature and humidity conditions on long-term creep displacement data of high strength Kevlar and VectranTM woven fabric webbings under constant load for inflatable structures is presented. The restraint layer of an inflatable structure for long-duration space exploration missions is designed to bear load and consists of an assembly of high strength webbings. Long-term creep displacement data of webbings can be utilized by designers to validate service life parameters of restraint layers of inflatable structures. Five groups of high-strength webbings were researched over a two year period. Each group had a unique webbing length, load rating, applied load, and test period. The five groups consisted of 1.) 6K Vectran webbings loaded to 49% ultimate tensile strength (UTS), 2.) 6K Vectran webbings loaded to 55% UTS, 3.) 12.5K Vectran webbings loaded to 22% UTS, 4.) 6K Kevlar webbings loaded to 40% and 43% UTS, and 5.) 6K Kevlar webbings loaded to 48% UTS. Results show that all webbing groups exhibit the initial two stages of three of a typical creep curve of an elastic material. Results also show that webbings exhibit unique local wave patterns over the duration of the test period. Data indicate that the local pattern is primarily generated by daily variations in relative humidity values within the test facility. Data indicate that after a three to six month period, where webbings reach a steady-state creep condition, an annual sinusoidal displacement pattern is exhibited, primarily due to variations in annual mean temperature values. Data indicates that variations in daily temperature values and annual mean humidity values have limited secondary effects on creep displacement behavior. Results show that webbings in groups 2 and 5 do not exhibit well defined annual displacement patterns because the magnitude of the applied loads cause large deformations, and data indicate that material yielding within a webbing tends to neutralize the annual sinusoidal displacement pattern. Study indicates that applied load, environmental effects, mechanical strength, coefficient of thermal expansion, and hygroscopic properties of webbings are fundamental requirements for quantifying accurate creep displacements and behaviors over multiple year time periods. Results from a study of the environmental effects on long-term creep displacement data of Kevlar and Vectran woven webbings are presented to increase the knowledge base of webbing materials and to enhance designs of inflatable space structures for long-duration space missions.

14 CFR 29.307 - Proof of structure.

Code of Federal Regulations, 2011 CFR

2011-01-01

... system, including control surfaces; (3) Operation tests of the control system; (4) Flight stress... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loading condition accounting for the environment to which the structure will be exposed in operation...

14 CFR 27.307 - Proof of structure.

Code of Federal Regulations, 2012 CFR

2012-01-01

... system, including control surfaces; (3) Operation tests of the control system; (4) Flight stress... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loading condition accounting for the environment to which the structure will be exposed in operation...

14 CFR 27.307 - Proof of structure.

Code of Federal Regulations, 2013 CFR

2013-01-01

... system, including control surfaces; (3) Operation tests of the control system; (4) Flight stress... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loading condition accounting for the environment to which the structure will be exposed in operation...

14 CFR 29.307 - Proof of structure.

Code of Federal Regulations, 2014 CFR

2014-01-01

... system, including control surfaces; (3) Operation tests of the control system; (4) Flight stress... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loading condition accounting for the environment to which the structure will be exposed in operation...

14 CFR 29.307 - Proof of structure.

Code of Federal Regulations, 2013 CFR

2013-01-01

... system, including control surfaces; (3) Operation tests of the control system; (4) Flight stress... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loading condition accounting for the environment to which the structure will be exposed in operation...

14 CFR 27.307 - Proof of structure.

Code of Federal Regulations, 2014 CFR

2014-01-01

... system, including control surfaces; (3) Operation tests of the control system; (4) Flight stress... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loading condition accounting for the environment to which the structure will be exposed in operation...

14 CFR 27.307 - Proof of structure.

Code of Federal Regulations, 2011 CFR

2011-01-01

... system, including control surfaces; (3) Operation tests of the control system; (4) Flight stress... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loading condition accounting for the environment to which the structure will be exposed in operation...

14 CFR 29.307 - Proof of structure.

Code of Federal Regulations, 2012 CFR

2012-01-01

... system, including control surfaces; (3) Operation tests of the control system; (4) Flight stress... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loading condition accounting for the environment to which the structure will be exposed in operation...

Lubricant evaluation of the alpha and beta joints, phase 2

NASA Technical Reports Server (NTRS)

Kannel, J. W.; Stockwell, R. D.

1992-01-01

A research study was conducted to evaluate dry film lubrication of long life space components such as the alpha and beta joints of the Space Station. The problem addressed in the report pertains to the longevity of sputtered MoS2 or ion plated lead films in a rolling contact environment. A special technique was devised for the experiments, which incorporated a coated ball cyclically loaded against a flat plate. At fixed intervals the surface of the coating was photographed at 100X magnification. By computer scanning the photographs, the rate of coating loss was determined. Experimental variables include load and surface finish of the plate. A theory was developed to analyze the state of stress between ball and flat. The stress condition in the ball apparatus was related to the state of stress under rolling contact conditions. Based on the experiments life appeared to decrease with increasing load and increasing surface roughness. An ion plated lead film gave better life than a sputtered MoS2 film. However, by keeping the interfacial shear stress at a low level, adequate coating life was achieved for either coating. For the lead film, the critical stress was about 0.19 GPa (28 ksi). The study dealt only with mechanical wear. Before a coating is selected for a critical space application, other factors such as reaction with atomic oxygen must also be considered.

CFD simulations of transient load change on a high head Francis turbine

NASA Astrophysics Data System (ADS)

Jakobsen, Ken-Robert G.; Aasved Holst, Martin

2017-01-01

Motivated by the importance of better understanding the structural integrity of high-head hydraulic turbines operating at intermittent conditions, complete 360º steady-state and transient simulations of a Francis turbine are presented in this paper. The main target of the work has been to investigate different numerical approaches such as mesh deformation for different operating conditions. Steady-state simulations were performed at the best efficiency point (BEP) and used as initial conditions for the transient simulations considering load rejection from BEP to part load (BEP2PL) and during load acceptance from BEP to high load (BEP2HL). Simulation results were compared with experimental data available for the Francis-99 project where close agreement was found for the mesh independent solution. The transient load analyses showed general trends in accordance with the measurement reports, especially for the pressure in vaneless space that is of high importance regarding RSI effects. Some deviations were identified for the net head at load rejection for which further investigations will be conducted. All CFD simulations were performed at model scale with ANSYS CFX v. 17 at either 96 or 120 cores (2.60 GHz). The immersed boundary technique was tested during the initial stages of the project, but had to be abandoned due to severe memory requirements. Pressure amplitudes and other instantaneous results were not considered.

Liquid Methane Testing With a Large-Scale Spray Bar Thermodynamic Vent System

NASA Technical Reports Server (NTRS)

Hastings, L. J.; Bolshinskiy, L. G.; Hedayat, A.; Flachbart, R. H.; Sisco, J. D.; Schnell. A. R.

2014-01-01

NASA's Marshall Space Flight Center conducted liquid methane testing in November 2006 using the multipurpose hydrogen test bed outfitted with a spray bar thermodynamic vent system (TVS). The basic objective was to identify any unusual or unique thermodynamic characteristics associated with densified methane that should be considered in the design of space-based TVSs. Thirteen days of testing were performed with total tank heat loads ranging from 720 to 420 W at a fill level of approximately 90%. It was noted that as the fluid passed through the Joule-Thompson expansion, thermodynamic conditions consistent with the pervasive presence of metastability were indicated. This Technical Publication describes conditions that correspond with metastability and its detrimental effects on TVS performance. The observed conditions were primarily functions of methane densification and helium pressurization; therefore, assurance must be provided that metastable conditions have been circumvented in future applications of thermodynamic venting to in-space methane storage.

Study of cryogenic propellant systems for loading the space shuttle

NASA Technical Reports Server (NTRS)

Voth, R. O.; Steward, W. G.; Hall, W. J.

1974-01-01

Computer programs were written to model the liquid oxygen loading system for the space shuttle. The programs allow selection of input data through graphic displays which schematically depict the part of the system being modeled. The computed output is also displayed in the form of graphs and printed messages. Any one of six computation options may be selected. The first four of these pertain to thermal stresses, pressure surges, cooldown times, flow rates and pressures during cooldown. Options five and six deal with possible water hammer effects due to closing of valves, steady flow and transient response to changes in operating conditions after cooldown. Procedures are given for operation of the graphic display unit and minicomputer.

Biomechanical Modeling Analysis of Loads Configuration for Squat Exercise

NASA Technical Reports Server (NTRS)

Gallo, Christopher A.; Thompson, William K.; Lewandowski, Beth E.; Jagodnik, Kathleen; De Witt, John K.

2017-01-01

INTRODUCTION: Long duration space travel will expose astronauts to extended periods of reduced gravity. Since gravity is not present to assist loading, astronauts will use resistive and aerobic exercise regimes for the duration of the space flight to minimize loss of bone density, muscle mass and aerobic capacity that occurs during exposure to a reduced gravity environment. Unlike the International Space Station (ISS), the area available for an exercise device in the next generation of spacecraft for travel to the Moon or to Mars is limited and therefore compact resistance exercise device prototypes are being developed. The Advanced Resistive Exercise Device (ARED) currently on the ISS is being used as a benchmark for the functional performance of these new devices. Biomechanical data collection and computational modeling aid the device design process by quantifying the joint torques and the musculoskeletal forces that occur during exercises performed on the prototype devices. METHODS The computational models currently under development utilize the OpenSim [1] software platform, consisting of open source code for musculoskeletal modeling, using biomechanical input data from test subjects for estimation of muscle and joint loads. The OpenSim Full Body Model [2] is used for all analyses. The model incorporates simplified wrap surfaces, a new knee model and updated lower body muscle parameters derived from cadaver measurements and magnetic resonance imaging of young adults. The upper body uses torque actuators at the lumbar and extremity joints. The test subjects who volunteer for this study are instrumented with reflective markers for motion capture data collection while performing squat exercising on the Hybrid Ultimate Lifting Kit (HULK) prototype device (ZIN Technologies, Middleburg Heights, OH). Ground reaction force data is collected with force plates under the feet, and device loading is recorded through load cells internal to the HULK. Test variables include the applied device load and the dual cable long bar or single cable T-bar interface between the test subject and the device. Data is also obtained using free weights with the identical loading for a comparison to the resistively loaded exercise device trials. The data drives the OpenSim biomechanical model, which has been scaled to match the anthropometrics of the test subject, to calculate the body loads. RESULTS Lower body kinematics, joint moments, joint forces and muscle forces are obtained from the OpenSim biomechanical analysis of the squat exercises under different loading conditions. Preliminary results from the model for the loading conditions will be presented as will hypotheses developed for follow on work.

Effects of Tactile, Visual, and Auditory Cues About Threat Location on Target Acquisition and Attention to Visual and Auditory Communications

DTIC Science & Technology

2006-08-01

Space Administration ( NASA ) Task Load Index ( TLX ...SITREP Questionnaire Example 33 Appendix C. NASA - TLX 35 Appendix D. Demographic Questionnaire 39 Appendix E. Post-Test Questionnaire 41...Mean ratings of physical demand by cue condition using NASA - TLX . ..................... 19 Figure 9. Mean ratings of temporal demand by cue condition

Evaluation of shuttle turbopump bearings

NASA Technical Reports Server (NTRS)

Dufrane, K. F.; Kannel, J. W.

1978-01-01

Because the high pressure turbopumps used on the space shuttle main engine (SSME) are high speed machines and rotor dynamics analysis of these units is very complicated, it was considered necessary to verify calculated turbomachinery shaft bearing loads by analysis of ball bearing load tracks. This report presents the methods used and the results of load track analysis on one set of bearings removed from a high pressure liquid oxygen turbopump which had been subjected to SSME static firing tests. This type of analysis was found useful in determining bearing operating conditions and for verifying rotor dynamics computer models.

Temperature Oscillations in Loop Heat Pipe Operation

NASA Technical Reports Server (NTRS)

Ku, Jentung; Ottenstein, Laura; Kobel, Mark; Rogers, Paul; Kaya, Tarik; Paquin, Krista C. (Technical Monitor)

2000-01-01

Loop heat pipes (LHPs) are versatile two-phase heat transfer devices that have gained increasing acceptance for space and terrestrial applications. The operating temperature of an LHP is a function of its operating conditions. The LHP usually reaches a steady operating temperature for a given heat load and sink temperature. The operating temperature will change when the heat load and/or the sink temperature changes, but eventually reaches another steady state in most cases. Under certain conditions, however, the loop operating temperature never really reaches a true steady state, but instead becomes oscillatory. This paper discusses the temperature oscillation phenomenon using test data from a miniature LHP.

Analytical model of the structureborne interior noise induced by a propeller wake

NASA Technical Reports Server (NTRS)

Junger, M. C.; Garrelick, J. M.; Martinez, R.; Cole, J. E., III

1984-01-01

The structure-borne contribution to the interior noise that is induced by the propeller wake acting on the wing was studied. Analytical models were developed to describe each aspect of this path including the excitation loads, the wing and fuselage structures, and the interior acoustic space. The emphasis is on examining a variety of parameters, and as a result different models were developed to examine specific parameters. The excitation loading on the wing by the propeller wake is modeled by a distribution of rotating potential vortices whose strength is related to the thrust per blade. The response of the wing to this loading is examined using beam models. A model of a beam structurally connected to a cylindrical shell with an internal acoustic fluid was developed to examine the coupling of energy from the wing to the interior space. The model of the acoustic space allows for arbitrary end conditions (e.g., rigid or vibrating end caps). Calculations are presented using these models to compare with a laboratory test configuration as well as for parameters of a prop-fan aircraft.

Context-dependency in the effects of nutrient loading and consumers on the availability of space in marine rocky environments.

PubMed

Bulleri, Fabio; Russell, Bayden D; Connell, Sean D

2012-01-01

Enhanced nutrient loading and depletion of consumer populations interact to alter the structure of aquatic plant communities. Nonetheless, variation between adjacent habitats in the relative strength of bottom-up (i.e. nutrients) versus top-down (i.e. grazing) forces as determinants of community structure across broad spatial scales remains unexplored. We experimentally assessed the importance of grazing pressure and nutrient availability on the development of macroalgal assemblages and the maintenance of unoccupied space in habitats differing in physical conditions (i.e. intertidal versus subtidal), across regions of contrasting productivity (oligotrophic coasts of South Australia versus the more productive coasts of Eastern Australia). In Eastern Australia, grazers were effective in maintaining space free of macroalgae in both intertidal and subtidal habitats, irrespective of nutrient levels. Conversely, in South Australia, grazers could not prevent colonization of space by turf-forming macroalgae in subtidal habitats regardless of nutrients levels, yet in intertidal habitats removal of grazers reduced unoccupied space when nutrients were elevated. Assessing the effects of eutrophication in coastal waters requires balancing our understanding between local consumer pressure and background oceanographic conditions that affect productivity. This broader-based understanding may assist in reconciling disproportionately large local-scale variation, a characteristic of ecology, with regional scale processes that are often of greater relevance to policy making and tractability to management.

Effect of roof strength in injury mitigation during pole impact.

PubMed

Friedman, Keith; Hutchinson, John; Mihora, Dennis; Kumar, Sri; Frieder, Russell; Sances, Anthony

2007-01-01

Motor vehicle accidents involving pole impacts often result in serious head and neck injuries to occupants. Pole impacts are typically associated with rollover and side collisions. During such events, the roof structure is often deformed into the occupant survival space. The existence of a strengthened roof structure would reduce roof deformation and accordingly provide better protection to occupants. The present study examines the effect of reinforced (strengthened) roofs using experimental crash study and computer model simulation. The experimental study includes the production cab structure of a pickup truck. The cab structure was loaded using an actual telephone pole under controlled laboratory conditions. The cab structure was subjected to two separate load conditions at the A-pillar and door frame. The contact force and deformation were measured using a force gauge and potentiometer, respectively. A computer finite element model was created to simulate the experimental studies. The results of finite element model matched well with experimental data during two different load conditions. The validated finite element model was then used to simulate a reinforced roof structure. The reinforced roof significantly reduced the structural deformations compared to those observed in the production roof. The peak deformation was reduced by approximately 75% and peak velocity was reduced by approximately 50%. Such a reduction in the deformation of the roof structure helps to maintain a safe occupant survival space.

Wind Loads on Flat Plate Photovoltaic Array Fields

NASA Technical Reports Server (NTRS)

Miller, R.; Zimmerman, D.

1979-01-01

The aerodynamic forces resulting from winds acting on flat plate photovoltaic arrays were investigated. Local pressure distributions and total aerodynamic forces on the arrays are shown. Design loads are presented to cover the conditions of array angles relative to the ground from 20 deg to 60 deg, variable array spacings, a ground clearance gap up to 1.2 m (4 ft) and array slant heights of 2.4 m (8 ft) and 4.8 m (16 ft). Several means of alleviating the wind loads on the arrays are detailed. The expected reduction of the steady state wind velocity with the use of fences as a load alleviation device are indicated to be in excess of a factor of three for some conditions. This yields steady state wind load reductions as much as a factor of ten compared to the load incurred if no fence is used to protect the arrays. This steady state wind load reduction is offset by the increase in turbulence due to the fence but still an overall load reduction of 2.5 can be realized. Other load alleviation devices suggested are the installation of air gaps in the arrays, blocking the flow under the arrays and rounding the edges of the array. A wind tunnel test plan to supplement the theoretical study and to evaluate the load alleviation devices is outlined.

Postural muscle atrophy prevention and recovery and bone remodelling through high frequency proprioception for astronauts

NASA Astrophysics Data System (ADS)

Riva, Dario; Rossitto, Franco; Battocchio, Luciano

2009-09-01

The difficulty in applying active exercises during space flights increases the importance of passive countermeasures, but coupling load and instability remains indispensable for generating high frequency (HF) proprioceptive flows and preventing muscle atrophy and osteoporosis. The present study, in microgravity conditions during a parabolic flight, verified whether an electronic system, composed of a rocking board, a postural reader and a bungee-cord loading apparatus creates HF postural instability comparable to that reachable on the Earth. Tracking the subject, in single stance, to real-time visual signals is necessary to obtain HF instability situations. The bungee-cord loading apparatus allowed the subject to manage the 81.5% body weight load (100% could easily be exceeded). A preliminary training programme schedule on the Earth and in space is suggested. Comparison with a pathological muscle atrophy is presented. The possibility of generating HF proprioceptive flows could complement current countermeasures for the prevention and recovery of muscle atrophy and osteoporosis in terrestrial and space environments. These exercises combine massive activation of spindles and joint receptors, applying simultaneously HF variations of pressure to different areas of the sole of the foot. This class of exercises could improve the effectiveness of current countermeasures, reducing working time and fatigue.

Apollo 4 launch

NASA Image and Video Library

1967-09-11

S67-50903 (9 Nov. 1967) --- The Apollo 4 (Spacecraft 017/Saturn 501) space mission was launched from Pad A, Launch Complex 39, Kennedy Space Center, Florida. The liftoff of the huge 363-feet tall Apollo/Saturn V space vehicle was at 7:00:01 a.m. (EST), Nov. 9, 1967. The successful objectives of the Apollo 4 Earth-orbital unmanned space mission obtained included (1) flight information on launch vehicle and spacecraft structural integrity and compatibility, flight loads, stage separation, subsystem operation, emergency detection subsystem, and (2) evaluation of the Apollo Command Module heat shield under conditions encountered on return from a moon mission.

The space shuttle program from challenge to achievement: Space exploration rolling on tires

NASA Technical Reports Server (NTRS)

Felder, G. L.

1985-01-01

The Space Shuttle Transportation System is the first space program to employ the pneumatic tire as a part of space exploration. For aircraft tires, this program establishes new expectations as to what constitutes acceptable performance within a set of tough environmental and operational conditions. Tire design, stresses the usual low weight, high load, high speed, and excellent air retention features but at extremes well outside industry standards. Tires will continue to be an integral part of the Shuttle's landing phase in the immediate future since they afford a unique combination of directional control, braking traction, flotation and shock absorption not available by other systems.

Environmental control/life support system for Space Station

NASA Technical Reports Server (NTRS)

Miller, C. W.; Heppner, D. B.; Schubert, F. H.; Dahlhausen, M. J.

1986-01-01

The functional, operational, and design load requirements for the Environmental Control/Life Support System (ECLSS) are described. The ECLSS is divided into two groups: (1) an atmosphere management group and (2) a water and waste management group. The interaction between the ECLSS and the Space Station Habitability System is examined. The cruciform baseline station design, the delta and big T module configuration, and the reference Space Station configuration are evaluated in terms of ECLSS requirements. The distribution of ECLSS equipment in a reference Space Station configuration is studied as a function of initial operating conditions and growth orbit capabilities. The benefits of water electrolysis as a Space Station utility are considered.

The effect of front-to-rear propeller spacing on the interaction noise at cruise conditions of a model counterrotation propeller having a reduced diameter aft propeller

NASA Technical Reports Server (NTRS)

Dittmar, James H.; Gordon, Eliott B.; Jeracki, Robert J.

1988-01-01

The effect of forward-to-aft propeller spacing on the interaction noise of a counterrotation propeller with reduced aft diameter was measured at cruise conditions. In general, the tones at 100 percent speed decreased from close to nominal spacing as expected from a wake decay model. However, when the spacing was further increased to the far position, the noise did not decrease as expected and in some cases increased. The behavior at the far spacing was attributed to changing forward propeller performance, which produced larger wakes. The results of this experiment indicate that simple wake decay model is sufficient to describe the behavior of the interaction noise only if the aerodynamic coupling of the two propellers does not change with spacing. If significant coupling occurs such that the loading of the forward propeller is altered, the interaction noise does not necessarily decrease with larger forward-to-aft propeller spacing.

A Model for Space Shuttle Orbiter Tire Side Forces Based on NASA Landing Systems Research Aircraft Test Results

NASA Technical Reports Server (NTRS)

Carter, John F.; Nagy, Christopher J.; Barnicki, Joseph S.

1997-01-01

Forces generated by the Space Shuttle orbiter tire under varying vertical load, slip angle, speed, and surface conditions were measured using the Landing System Research Aircraft (LSRA). Resulting data were used to calculate a mathematical model for predicting tire forces in orbiter simulations. Tire side and drag forces experienced by an orbiter tire are cataloged as a function of vertical load and slip angle. The mathematical model is compared to existing tire force models for the Space Shuttle orbiter. This report describes the LSRA and a typical test sequence. Testing methods, data reduction, and error analysis are presented. The LSRA testing was conducted on concrete and lakebed runways at the Edwards Air Force Flight Test Center and on concrete runways at the Kennedy Space Center (KSC). Wet runway tire force tests were performed on test strips made at the KSC using different surfacing techniques. Data were corrected for ply steer forces and conicity.

Application of Hybrid Optimization-Expert System for Optimal Power Management on Board Space Power Station

NASA Technical Reports Server (NTRS)

Momoh, James; Chattopadhyay, Deb; Basheer, Omar Ali AL

1996-01-01

The space power system has two sources of energy: photo-voltaic blankets and batteries. The optimal power management problem on-board has two broad operations: off-line power scheduling to determine the load allocation schedule of the next several hours based on the forecast of load and solar power availability. The nature of this study puts less emphasis on speed requirement for computation and more importance on the optimality of the solution. The second category problem, on-line power rescheduling, is needed in the event of occurrence of a contingency to optimally reschedule the loads to minimize the 'unused' or 'wasted' energy while keeping the priority on certain type of load and minimum disturbance of the original optimal schedule determined in the first-stage off-line study. The computational performance of the on-line 'rescheduler' is an important criterion and plays a critical role in the selection of the appropriate tool. The Howard University Center for Energy Systems and Control has developed a hybrid optimization-expert systems based power management program. The pre-scheduler has been developed using a non-linear multi-objective optimization technique called the Outer Approximation method and implemented using the General Algebraic Modeling System (GAMS). The optimization model has the capability of dealing with multiple conflicting objectives viz. maximizing energy utilization, minimizing the variation of load over a day, etc. and incorporates several complex interaction between the loads in a space system. The rescheduling is performed using an expert system developed in PROLOG which utilizes a rule-base for reallocation of the loads in an emergency condition viz. shortage of power due to solar array failure, increase of base load, addition of new activity, repetition of old activity etc. Both the modules handle decision making on battery charging and discharging and allocation of loads over a time-horizon of a day divided into intervals of 10 minutes. The models have been extensively tested using a case study for the Space Station Freedom and the results for the case study will be presented. Several future enhancements of the pre-scheduler and the 'rescheduler' have been outlined which include graphic analyzer for the on-line module, incorporating probabilistic considerations, including spatial location of the loads and the connectivity using a direct current (DC) load flow model.

Countermeasures for Maintenance of Cardiovascular and Muscle Function in Space Flight

NASA Technical Reports Server (NTRS)

1997-01-01

In this session, Session FA2, the discussion focuses on the following topics: Effects of Repeated Long Duration +2Gz Load on Man's Cardiovascular Function; Certain Approaches to the Development of On-Board Automated Training System; Cardiac, Arterial, and Venous Adaptation to Og during 6 Month MIR-Spaceflights with and without "Thigh Cuffs" (93-95); Space Cycle(TM) Induced Physiologic Responses; Muscular Deconditioning During Long-term Spaceflight Exercise Recommendations to Optimize Crew Performance; Structure And Function of Knee Extensors After Long-Duration Spaceflight in Man, Effects of Countermeasure Exercise Training; Force and power characteristics of an exercise ergometer designed for use in space; and The simulating of overgravity conditions for astronauts' motor apparatus at the conditions of the training for orbital flights.

14 CFR 25.307 - Proof of structure.

Code of Federal Regulations, 2012 CFR

2012-01-01

... load tests may be inadequate. (b)-(c) [Reserved] (d) When static or dynamic tests are used to show... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... condition. Structural analysis may be used only if the structure conforms to that for which experience has...

14 CFR 25.307 - Proof of structure.

Code of Federal Regulations, 2010 CFR

2010-01-01

... load tests may be inadequate. (b)-(c) [Reserved] (d) When static or dynamic tests are used to show... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... condition. Structural analysis may be used only if the structure conforms to that for which experience has...

14 CFR 25.307 - Proof of structure.

Code of Federal Regulations, 2013 CFR

2013-01-01

... load tests may be inadequate. (b)-(c) [Reserved] (d) When static or dynamic tests are used to show... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... condition. Structural analysis may be used only if the structure conforms to that for which experience has...

14 CFR 25.307 - Proof of structure.

Code of Federal Regulations, 2014 CFR

2014-01-01

... load tests may be inadequate. (b)-(c) [Reserved] (d) When static or dynamic tests are used to show... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... condition. Structural analysis may be used only if the structure conforms to that for which experience has...

14 CFR 25.307 - Proof of structure.

Code of Federal Regulations, 2011 CFR

2011-01-01

... load tests may be inadequate. (b)-(c) [Reserved] (d) When static or dynamic tests are used to show... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... condition. Structural analysis may be used only if the structure conforms to that for which experience has...

Integrated dynamic analysis simulation of space stations with controllable solar array

NASA Technical Reports Server (NTRS)

Heinrichs, J. A.; Fee, J. J.

1972-01-01

A methodology is formulated and presented for the integrated structural dynamic analysis of space stations with controllable solar arrays and non-controllable appendages. The structural system flexibility characteristics are considered in the dynamic analysis by a synthesis technique whereby free-free space station modal coordinates and cantilever appendage coordinates are inertially coupled. A digital simulation of this analysis method is described and verified by comparison of interaction load solutions with other methods of solution. Motion equations are simulated for both the zero gravity and artificial gravity (spinning) orbital conditions. Closed loop controlling dynamics for both orientation control of the arrays and attitude control of the space station are provided in the simulation by various generic types of controlling systems. The capability of the simulation as a design tool is demonstrated by utilizing typical space station and solar array structural representations and a specific structural perturbing force. Response and interaction load solutions are presented for this structural configuration and indicate the importance of using an integrated type analysis for the predictions of structural interactions.

Digital data processing system dynamic loading analysis

NASA Technical Reports Server (NTRS)

Lagas, J. J.; Peterka, J. J.; Tucker, A. E.

1976-01-01

Simulation and analysis of the Space Shuttle Orbiter Digital Data Processing System (DDPS) are reported. The mated flight and postseparation flight phases of the space shuttle's approach and landing test configuration were modeled utilizing the Information Management System Interpretative Model (IMSIM) in a computerized simulation modeling of the ALT hardware, software, and workload. System requirements simulated for the ALT configuration were defined. Sensitivity analyses determined areas of potential data flow problems in DDPS operation. Based on the defined system requirements and the sensitivity analyses, a test design is described for adapting, parameterizing, and executing the IMSIM. Varying load and stress conditions for the model execution are given. The analyses of the computer simulation runs were documented as results, conclusions, and recommendations for DDPS improvements.

Space shuttle orbiter digital data processing system timing sensitivity analysis OFT ascent phase

NASA Technical Reports Server (NTRS)

Lagas, J. J.; Peterka, J. J.; Becker, D. A.

1977-01-01

Dynamic loads were investigated to provide simulation and analysis of the space shuttle orbiter digital data processing system (DDPS). Segments of the ascent test (OFT) configuration were modeled utilizing the information management system interpretive model (IMSIM) in a computerized simulation modeling of the OFT hardware and software workload. System requirements for simulation of the OFT configuration were defined, and sensitivity analyses determined areas of potential data flow problems in DDPS operation. Based on the defined system requirements and these sensitivity analyses, a test design was developed for adapting, parameterizing, and executing IMSIM, using varying load and stress conditions for model execution. Analyses of the computer simulation runs are documented, including results, conclusions, and recommendations for DDPS improvements.

Single-Event Transients in Voltage Regulators

NASA Technical Reports Server (NTRS)

Johnston, Allan H.; Miyahira, Tetsuo F.; Irom, F.; Laird, Jamie S.

2006-01-01

Single-event transients are investigated for two voltage regulator circuits that are widely used in space. A circuit-level model is developed that can be used to determine how transients are affected by different circuit application conditions. Internal protection circuits-which are affected by load as well as internal thermal effects-can also be triggered from heavy ions, causing dropouts or shutdown ranging from milliseconds to seconds. Although conventional output transients can be reduced by adding load capacitance, that approach is ineffective for dropouts from protection circuitry.

Validating Savings Claims of Cold Climate Zero Energy Ready Homes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williamson, J.; Puttagunta, S.

This report details the validation methods used to analyze consumption at each of these homes. It includes a detailed end-use examination of consumptions from the following categories: 1) Heating, 2) Cooling, 3) Lights, Appliances, and Miscellaneous Electric Loads (LAMELS) along with Domestic Hot Water Use, 4) Ventilation, and 5) PV generation. A utility bill disaggregation method, which allows a crude estimation of space conditioning loads based on outdoor air temperature, was also performed and the results compared to the actual measured data.

A vacuum four-ball tribometer to evaluate liquid lubricants for space applications

NASA Technical Reports Server (NTRS)

Masuko, Masabumi; Jones, William R., Jr.; Jansen, Ralph; Ebihara, Ben; Pepper, Stephen V.; Helmick, Larry S.

1993-01-01

The design and operation of a vacuum tribometer, based on the four-ball configuration, is described. This tribometer evaluates the tribological characteristics of liquid lubricants for space applications. Operating conditions include: room temperature, loads to approximately 1000N, speeds to approximately 500 rpm, and pressures of approximately 10(exp -6)Pa. Tests can also be run at atmospheric pressure with air or nitrogen. Some typical test results are included.

Improved dynamic analysis method using load-dependent Ritz vectors

NASA Technical Reports Server (NTRS)

Escobedo-Torres, J.; Ricles, J. M.

1993-01-01

The dynamic analysis of large space structures is important in order to predict their behavior under operating conditions. Computer models of large space structures are characterized by having a large number of degrees of freedom, and the computational effort required to carry out the analysis is very large. Conventional methods of solution utilize a subset of the eigenvectors of the system, but for systems with many degrees of freedom, the solution of the eigenproblem is in many cases the most costly phase of the analysis. For this reason, alternate solution methods need to be considered. It is important that the method chosen for the analysis be efficient and that accurate results be obtainable. It is important that the method chosen for the analysis be efficient and that accurate results be obtainable. The load dependent Ritz vector method is presented as an alternative to the classical normal mode methods for obtaining dynamic responses of large space structures. A simplified model of a space station is used to compare results. Results show that the load dependent Ritz vector method predicts the dynamic response better than the classical normal mode method. Even though this alternate method is very promising, further studies are necessary to fully understand its attributes and limitations.

The Effects of Elbow Bracing on Medial Elbow Joint Space Gapping Associated With Repetitive Throwing in High School Baseball Players

PubMed Central

Hattori, Hiroshi; Akasaka, Kiyokazu; Otsudo, Takahiro; Takei, Keiichi; Yamamoto, Mitsuru

2017-01-01

Background: Throwing athletes risk medial elbow injury from extreme valgus stress generated across the medial elbow during throwing. Braces have been developed to protect the elbow joint; however, no previous study has investigated the effects of elbow bracing on medial elbow joint space gapping associated with repetitive throwing. Hypothesis/Purpose: The purpose of this study was to investigate the effects of elbow bracing on medial elbow joint space gapping during repetitive throwing. Our hypothesis was that an elbow brace may reduce mechanical stress on the elbow by reducing medial elbow joint space gapping. Study Design: Controlled laboratory study. Methods: Twenty-five high school baseball players participated in this study. Each subject pitched 100 times under 2 conditions: control (without elbow brace) and elbow brace. The ulnohumeral joint space was measured ultrasonically before pitching and after every block of 20 pitches. Measurement of the ulnohumeral joint space was carried out using ultrasound with the forearm hanging by the side. Two-way repeated-measures analysis of variance and post hoc tests were used to compare ulnohumeral joint space with repeated pitching and between the elbow brace and control conditions. Results: In the control condition, ulnohumeral joint space after 60 pitches was significantly greater than that before pitching (P < .01). In contrast, in the elbow brace condition, ulnohumeral joint space was not significantly different after repeated pitching. When comparing these 2 conditions, ulnohumeral joint space in the control condition was significantly greater than that in the elbow brace condition after 60 pitches (P < .01). Conclusion: An elbow brace has the effect of preventing medial elbow joint space gapping with repeated throwing when determined ultrasonically by measuring the ulnohumeral joint space under gravity load. Clinical Relevance: An elbow brace worn during baseball pitching practice may help reduce mechanical stress on the elbow by reducing medial elbow joint space gapping. PMID:28451622

The Effects of Elbow Bracing on Medial Elbow Joint Space Gapping Associated With Repetitive Throwing in High School Baseball Players.

PubMed

Hattori, Hiroshi; Akasaka, Kiyokazu; Otsudo, Takahiro; Takei, Keiichi; Yamamoto, Mitsuru

2017-04-01

Throwing athletes risk medial elbow injury from extreme valgus stress generated across the medial elbow during throwing. Braces have been developed to protect the elbow joint; however, no previous study has investigated the effects of elbow bracing on medial elbow joint space gapping associated with repetitive throwing. The purpose of this study was to investigate the effects of elbow bracing on medial elbow joint space gapping during repetitive throwing. Our hypothesis was that an elbow brace may reduce mechanical stress on the elbow by reducing medial elbow joint space gapping. Controlled laboratory study. Twenty-five high school baseball players participated in this study. Each subject pitched 100 times under 2 conditions: control (without elbow brace) and elbow brace. The ulnohumeral joint space was measured ultrasonically before pitching and after every block of 20 pitches. Measurement of the ulnohumeral joint space was carried out using ultrasound with the forearm hanging by the side. Two-way repeated-measures analysis of variance and post hoc tests were used to compare ulnohumeral joint space with repeated pitching and between the elbow brace and control conditions. In the control condition, ulnohumeral joint space after 60 pitches was significantly greater than that before pitching ( P < .01). In contrast, in the elbow brace condition, ulnohumeral joint space was not significantly different after repeated pitching. When comparing these 2 conditions, ulnohumeral joint space in the control condition was significantly greater than that in the elbow brace condition after 60 pitches ( P < .01). An elbow brace has the effect of preventing medial elbow joint space gapping with repeated throwing when determined ultrasonically by measuring the ulnohumeral joint space under gravity load. An elbow brace worn during baseball pitching practice may help reduce mechanical stress on the elbow by reducing medial elbow joint space gapping.

Tests of a sputtered MoS2 lubricant film in various environments

NASA Technical Reports Server (NTRS)

Vest, C. E.

1976-01-01

This paper discusses conditions and results of several tests of a DC sputtered MoS2 dry lubricant film. The test components were miniature precision ball bearings and rings and blocks; the surrounding atmospheres were laboratory air, pure helium, vacuum to 10 to the -8th power torr, and a perfluoroalkylpolyether oil. The results showed that the lubricant would perform satisfactorily under lightly loaded (450 gm) ball bearings in vacuum and would not perform well under a 66-kg load in air, a 132-kg load in helium, or a 330-kg load under oil. These tests and others show that the sputtered MoS2 film has some desirable features for space applications as well as some definite limitations.

Is there resetting of central venous pressure in microgravity?

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Ludwig, D. A.; Elliott, J. J.; Wade, C. E.

2001-01-01

In the early phase of the Space Shuttle program, NASA flight surgeons implemented a fluid-loading countermeasure in which astronauts were instructed to ingest eight 1-g salt tablets with 960 ml of water approximately 2 hours prior to reentry from space. This fluid loading regimen was intended to enhance orthostatic tolerance by replacing circulating plasma volume reduced during the space mission. Unfortunately, fluid loading failed to replace plasma volume in groundbased experiments and has proven minimally effective as a countermeasure against post-spaceflight orthostatic intolerance. In addition to the reduction of plasma volume, central venous pressure (CVP) is reduced during exposure to actual and groundbased analogs of microgravity. In the present study, we hypothesized that the reduction in CVP due to exposure to microgravity represents a resetting of the CVP operating point to a lower threshold. A lower CVP 'setpoint' might explain the failure of fluid loading to restore plasma volume. In order to test this hypothesis, we conducted an investigation in which we administered an acute volume load (stimulus) and measured responses in CVP, plasma volume and renal functions. If our hypothesis is true, we would expect the elevation in CVP induced by saline infusion to return to its pre-infusion levels in both HDT and upright control conditions despite lower vascular volume during HDT. In contrast to previous experiments, our approach is novel in that it provides information on alterations in CVP and vascular volume during HDT that are necessary for interpretation of the proposed CVP operating point resetting hypothesis.

Structural response of SSME turbine blade airfoils

NASA Technical Reports Server (NTRS)

Arya, V. K.; Abdul-Aziz, A.; Thompson, R. L.

1988-01-01

Reusable space propulsion hot gas-path components are required to operate under severe thermal and mechanical loading conditions. These operating conditions produce elevated temperature and thermal transients which results in significant thermally induced inelastic strains, particularly, in the turbopump turbine blades. An inelastic analysis for this component may therefore be necessary. Anisotropic alloys such as MAR M-247 or PWA-1480 are being considered to meet the safety and durability requirements of this component. An anisotropic inelastic structural analysis for an SSME fuel turbopump turbine blade was performed. The thermal loads used resulted from a transient heat transfer analysis of a turbine blade. A comparison of preliminary results from the elastic and inelastic analyses is presented.

Using Whole-House Field Tests to Empirically Derive Moisture Buffering Model Inputs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woods, J.; Winkler, J.; Christensen, D.

2014-08-01

Building energy simulations can be used to predict a building's interior conditions, along with the energy use associated with keeping these conditions comfortable. These models simulate the loads on the building (e.g., internal gains, envelope heat transfer), determine the operation of the space conditioning equipment, and then calculate the building's temperature and humidity throughout the year. The indoor temperature and humidity are affected not only by the loads and the space conditioning equipment, but also by the capacitance of the building materials, which buffer changes in temperature and humidity. This research developed an empirical method to extract whole-house model inputsmore » for use with a more accurate moisture capacitance model (the effective moisture penetration depth model). The experimental approach was to subject the materials in the house to a square-wave relative humidity profile, measure all of the moisture transfer terms (e.g., infiltration, air conditioner condensate) and calculate the only unmeasured term: the moisture absorption into the materials. After validating the method with laboratory measurements, we performed the tests in a field house. A least-squares fit of an analytical solution to the measured moisture absorption curves was used to determine the three independent model parameters representing the moisture buffering potential of this house and its furnishings. Follow on tests with realistic latent and sensible loads showed good agreement with the derived parameters, especially compared to the commonly-used effective capacitance approach. These results show that the EMPD model, once the inputs are known, is an accurate moisture buffering model.« less

A multi-purpose method for analysis of spur gear tooth loading

NASA Technical Reports Server (NTRS)

Kasuba, R.; Evans, J. W.; August, R.; Frater, J. L.

1981-01-01

A large digitized approach was developed for the static and dynamic load analysis of spur gearing. An iterative procedure was used to calculate directly the "variable-variable" gear mesh stiffness as a function of transmitted load, gear tooth profile errors, gear tooth deflections and gear hub torsional deformation, and position of contacting profile points. The developed approach can be used to analyze the loads, Hertz stresses, and PV for the normal and high contrast ratio gearing, presently the modeling is limited to the condition that for a given gear all teeth have identical spacing and profiles (with or without surface imperfections). Certain types of simulated sinusoidal profile errors and pitting can cause interruptions of the gear mesh stiffness function and, thus, increase the dynamic loads in spur gearing. In addition, a finite element stress and mesh subprogram was developed for future introduction into the main program for calculating the gear tooth bending stresses under dynamic loads.

Changes of vessel-cells complex in zones of adaptive remodeling of the bone tissue under microgravity conditions

NASA Astrophysics Data System (ADS)

Rodionova, N.; Oganov, V.; Nosova, L.

The development and differentiation of osteogenic cells in organism happen in closely topographical and functional connection with blood capillaries. We formerly proofed, that small-differentiated cells, which are in the population of perivascular cells are osteogenic cells -precursors . At the present time it is actually to clear up, how these biostructures react on conditions of less of biomechanical load on skeleton bones. We researched peculiarities of blood-bed structure and perivascular cells in metaphises of thighbones and tibial bones in rats, which were onboard the American space station SLS-2 and in experiments of modeling hypokinesia. There were used methods of cytochemistry, histology and electron microscopy. We established, that under the support and functional load decreasing in zones of bones adaptive remodeling, comparatively to control, on histosections the own volume of sinusoid capillaries reduces. The small vessels prevail here. The spaces of sinusoid capillaries are limited by 1 2 cells of the endothelia. Endotheliocytes in- general have the typical ultrastructure. Basal membranes are expressed not-distinctly. Perivascular cells don't create the unbroken layer. The population of these cells is not-homogeneous. It includes enclosed to endothelia small-differentiated forms and separating cells with sings of fibroblastic differentiation (the own volume of rough endoplasmic reticulum in cytoplasm induces). The part of these cells reacts on the alkaline phosphatase (the marker of the osteogenic differentiation). Under the conditions of support load decreasing (especially under the microgravity) there is a tendency to reducing of separating osteogenic cells number. We noted the priority of differentiating fibroblasts. It leads to further development in zones of bone remodeling of hearths of fibrous tissue, that doesn't mineralize. The obtained data are seen as one of mechanisms of osteoporosis and osteopenia development under the deficite of support load.

Humidity data for 9975 shipping packages with cane fiberboard

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daugherty, W. L.

The 9975 surveillance program is developing a technical basis to support extending the storage period of 9975 packages in K-Area Complex beyond the currently approved 15 years. A key element of this effort is developing a better understanding of degradation of the fiberboard assembly under storage conditions. This degradation is influenced greatly by the moisture content of the fiberboard, which is not well characterized on an individual package basis. Direct measurements of humidity and fiberboard moisture content have been made on two test packages with cane fiberboard and varying internal heat levels from 0 up to 19W. With an internalmore » heat load, a temperature gradient in the fiberboard assembly leads to varying relative humidity in the air around the fiberboard. However, the absolute humidity tends to remain approximately constant throughout the package. The moisture content of fiberboard varies under the influence of several phenomena. Changes in local fiberboard temperature (from an internal heat load) can cause fiberboard moisture changes through absorption or evaporation. Fiberboard degradation at elevated temperature will produce water as a byproduct. And the moisture level within the package is constantly seeking equilibrium with that of the surrounding room air, which varies on a daily and seasonal basis. One indicator of the moisture condition within a 9975 package might be obtained by measuring the relative humidity in the upper air space, by inserting a humidity probe through a caplug hole. However, the data indicate that for the higher internal heat loads (15 and 19 watts), a large variation in internal moisture conditions produces little or no variation in the air space relative humidity. Therefore, this approach does not appear to be sensitive to fiberboard moisture variations at the higher heat loads which are of most interest to maintaining fiberboard integrity.« less

Skylab

NASA Image and Video Library

1971-06-01

The Apollo Telescope Mount (ATM) was one of four major components of Skylab that were designed and constructed under the management of the Marshall Space Flight Center (MSFC). In this photograph, an ATM is seen sitting inside the MSFC's Structural Load Test Arnex where the main structural elements were simulated under launch conditions.

Debris/ice/TPS assessment and photographic analysis for shuttle mission STS-35

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.; Higginbotham, Scott A.; Davis, James Bradley

1991-01-01

A debris/ice/Thermal Protection System (TPS) assessment and photographic analysis was conducted for Space Shuttle Mission STS-35. Debris inspections of the flight elements and launch pad were performed before and after the launch. Ice/frost conditions on the External Tank were assessed by the use of computer programs, monographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography was analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. Documented here are the debris/ice/TPS conditions and photographic analysis of Mission STS-35, and the overall effect of these conditions on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Photographic Analysis for Shuttle Mission STS-39

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.; Higginbotham, Scott A.; Davis, J. Bradley

1991-01-01

A Debris/Ice/TPS (thermal protection system) assessment and photographic analysis was conducted for Space Shuttle Mission STS-39. Debris inspections of the flight elements and launch pad were performed before and after launch. Ice/frost conditions on the external tank were assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography of launch was analyzed to identify ice/debris anomalies. The debris/ice/TPS conditions and photographic analysis of Mission STS-39, and their overall effect on the Space Shuttle Program are documented.

Mockup Small-Diameter Air Distribution System

DOE Office of Scientific and Technical Information (OSTI.GOV)

A. Poerschke and A. Rudd

2016-05-01

This report investigates the feasibility of using a home-run manifold small-diameter duct system to provide space conditioning air to individual thermal zones in a low-load home. This compact layout allows duct systems to be brought easily within conditioned space via interior partition walls. Centrally locating the air hander unit in the house significantly reduces duct lengths. The plenum box is designed so that each connected duct receives an equal amount of airflow, regardless of the duct position on the box. Furthermore, within a reasonable set of length restrictions, each duct continues to receive similar airflow. The design method uses anmore » additive approach to reach the total needed zonal airflow. Once the cubic feet per minute needed to satisfy the thermal load of a zone has been determined, the total number of duct runs to a zone can be calculated by dividing the required airflow by the standard airflow from each duct. The additive approach greatly simplifies the design effort and reduces the potential for duct design mistakes to be made. Measured results indicate that this plenum design can satisfy the heating load. However, the total airflow falls short of satisfying the cooling load in a hypothetical building. Static pressure inside the plenum box of 51.5 Pa limited the total airflow of the attached mini-split heat pump blower, thus limiting the total thermal capacity. Fan energy consumption is kept to 0.16 to 0.22 watt/CFM by using short duct runs and smooth duct material.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

This report investigates the feasibility of using a home-run manifold small-diameter duct system to provide space conditioning air to individual thermal zones in a low-load home. This compact layout allows duct systems to be brought easily within conditioned space via interior partition walls. Centrally locating the air hander unit in the house significantly reduces duct lengths. The plenum box is designed so that each connected duct receives an equal amount of airflow, regardless of the duct position on the box. Furthermore, within a reasonable set of length restrictions, each duct continues to receive similar airflow. The design method uses anmore » additive approach to reach the total needed zonal airflow. Once the cubic feet per minute needed to satisfy the thermal load of a zone has been determined, the total number of duct runs to a zone can be calculated by dividing the required airflow by the standard airflow from each duct. The additive approach greatly simplifies the design effort and reduces the potential for duct design mistakes to be made. Measured results indicate that this plenum design can satisfy the heating load. However, the total airflow falls short of satisfying the cooling load in a hypothetical building. Static pressure inside the plenum box of 51.5 Pa limited the total airflow of the attached mini-split heat pump blower, thus limiting the total thermal capacity. Fan energy consumption is kept to 0.16 to 0.22 watt/CFM by using short duct runs and smooth duct material.« less

Simulation of tree shade impacts on residential energy use for space conditioning in Sacramento

NASA Astrophysics Data System (ADS)

Simpson, J. R.; McPherson, E. G.

Tree shade reduces summer air conditioning demand and increases winter heating load by intercepting solar energy that would otherwise heat the shaded structure. We evaluate the magnitude of these effects here for 254 residential properties participating in a utility sponsored tree planting program in Sacramento, California. Tree and building characteristics and typical weather data are used to model hourly shading and energy used for space conditioning for each building for a period of one year. There were an average of 3.1 program trees per property which reduced annual and peak (8 h average from 1 to 9 p.m. Pacific Daylight Time) cooling energy use 153 kWh (7.1%) and 0.08 kW (2.3%) per tree, respectively. Annual heating load increased 0.85 GJ (0.80 MBtu, 1.9%) per tree. Changes in cooling load were smaller, but percentage changes larger, for newer buildings. Averaged over all homes, annual cooling savings of 15.25 per tree were reduced by a heating penalty of 5.25 per tree, for net savings of 10.00 per tree from shade. We estimate an annual cooling penalty of 2.80 per tree and heating savings of 6.80 per tree from reduced wind speed, for a net savings of 4.00 per tree, and total annual savings of 14.00 per tree (43.00 per property). Results are found to be consistent with previous simulations and the limited measurements available.

Evaluation of MPLM Design and Mission 6A Coupled Loads Analyses

NASA Technical Reports Server (NTRS)

Bookout, Paul S.; Ricks, Ed

1999-01-01

Through the development of a space shuttle payload, there are usually several coupled loads analyses (CLA) performed: preliminary design, critical design, final design and verification loads analysis (VLA). A final design CLA is the last analysis conducted prior to model delivery to the shuttle program for the VLA. The finite element models used in the final design CLA and the VLA are test verified dynamic math models. Mission 6A is the first of many flights of the Multi-Purpose Logistics Module (MPLM). The MPLM was developed by Alenia Spazio S.p.A. (an Italian aerospace company) and houses the International Standard Payload Racks (ISPR) for transportation to the space station in the shuttle. Marshall Space Flight Center (MSFC), the payload integrator of the MPLM for Mission 6A, performed the final design CLA using the M6.OZC shuttle data for liftoff and landing conditions using the proper shuttle cargo manifest. Alenia performed the preliminary and critical design CLAs for the development of the MPLM. However, these CLAs did not use the current Mission 6A cargo manifest. An evaluation of the preliminary and critical design performed by Alenia and the final design performed by MSFC is presented.

Space shuttle I-tube radiator testing at Johnson Space Center, May 1976, volume 1

NASA Technical Reports Server (NTRS)

Scheps, P. B.

1976-01-01

During the two weeks of thermal vacuum testing a representative forward panel was successfully operated in a variety of simulated environmental conditions. Performance limits for both high and low load operations were established. Confidence in the stable operation of the panel throughout its typical operating range was verified by the testing, and design studies were conducted to analyze the effects of the payload bay door, and the panel deployment angle, on performance.

9 CFR 3.90 - Care in transit.

Code of Federal Regulations, 2014 CFR

2014-01-01

... primates in commerce must ensure that the operator of the conveyance or a person accompanying the operator... nonhuman primates whenever they are loaded and unloaded and whenever the animal cargo space is otherwise..., it must not be transported in commerce, except to receive veterinary care for the condition. (d...

Adaptive servo control for umbilical mating

NASA Technical Reports Server (NTRS)

Zia, Omar

1988-01-01

Robotic applications at Kennedy Space Center are unique and in many cases require the fime positioning of heavy loads in dynamic environments. Performing such operations is beyond the capabilities of an off-the-shelf industrial robot. Therefore Robotics Applications Development Laboratory at Kennedy Space Center has put together an integrated system that coordinates state of the art robotic system providing an excellent easy to use testbed for NASA sensor integration experiments. This paper reviews the ways of improving the dynamic response of the robot operating under force feedback with varying dynamic internal perturbations in order to provide continuous stable operations under variable load conditions. The goal is to improve the stability of the system with force feedback using the adaptive control feature of existing system over a wide range of random motions. The effect of load variations on the dynamics and the transfer function (order or values of the parameters) of the system has been investigated, more accurate models of the system have been determined and analyzed.

Stability testing and analysis of a PMAD dc test bed for the Space Station Freedom

NASA Technical Reports Server (NTRS)

Button, Robert M.; Brush, Andrew S.

1992-01-01

The Power Management and Distribution (PMAD) dc Test Bed at the NASA Lewis Research Center is introduced. Its usefulness to the Space Station Freedom Electrical Power (EPS) development and design are discussed in context of verifying system stability. Stability criteria developed by Middlebrook and Cuk are discussed as they apply to constant power dc to dc converters exhibiting negative input impedance at low frequencies. The utility-type Secondary Subsystem is presented and each component is described. The instrumentation used to measure input and output impedance under load is defined. Test results obtained from input and output impedance measurements of test bed components are presented. It is shown that the PMAD dc Test Bed Secondary Subsystem meets the Middlebrook stability criterion for certain loading conditions.

Stability Testing and Analysis of a PMAD DC Test Bed for the Space Station Freedom

NASA Technical Reports Server (NTRS)

Button, Robert M.; Brush, Andrew S.

1992-01-01

The Power Management and Distribution (PMAD) DC Test Bed at the NASA Lewis Research Center is introduced. Its usefulness to the Space Station Freedom Electrical Power (EPS) development and design are discussed in context of verifying system stability. Stability criteria developed by Middlebrook and Cuk are discussed as they apply to constant power DC to DC converters exhibiting negative input impedance at low frequencies. The utility-type Secondary Subsystem is presented and each component is described. The instrumentation used to measure input and output impedance under load is defined. Test results obtained from input and output impedance measurements of test bed components are presented. It is shown that the PMAD DC Test Bed Secondary Subsystem meets the Middlebrook stability criterion for certain loading conditions.

Solar heating system at Quitman County Bank, Marks, Mississippi

NASA Technical Reports Server (NTRS)

1980-01-01

Information on the Solar Energy Heating System installed in a single story wood frame, cedar exterior, sloped roof building is presented. The system has on-site temperature and power measurements readouts. The 468 square feet of Solaron air flat plate collectors provide for 2,000 square feet of space heating, an estimated 60 percent of the heating load. Solar heated air is distributed to the 235 cubic foot rock storage box or to the load (space heating) by a 960 cubic feet per minute air handler unit. A 7.5 ton Carrier air-to-air heat pump with 15 kilowatts of electric booster strips serve as a back-up (auxiliary) to the solar system. Motorized dampers control the direction of airflow and back draft dampers prevent thermal siphoning of conditioned air.

Nonlinear Analysis of the Space Shuttle Superlightweight LO2 Tank. Part 2; Behavior Under 3g End-of-Flight Loads

NASA Technical Reports Server (NTRS)

Nemeth, Michael P.; Young, Richard D.; Collins, Timothy J.; Starnes, James H.,Jr.

1998-01-01

Results of linear bifurcation and nonlinear analyses of the Space Shuttle super lightweight (SLWT) external liquid-oxygen (LO2) tank are presented for an important end-of-flight loading condition. These results illustrate an important type of response mode for thin-walled shells, that are subjected to combined mechanical and thermal loads, that may be encountered in the design of other liquid-fuel launch vehicles. Linear bifurcation analyses are presented that predict several nearly equal eigenvalues that correspond to local buckling modes in the aft dome of the LO2 tank. In contrast, the nonlinear response phenomenon is shown to consist of a short-wavelength bending deformation in the aft elliptical dome of the LO2 tank that grows in amplitude in a stable manner with increasing load. Imperfection sensitivity analyses are presented that show that the presence of several nearly equal eigenvalues does not lead to a premature general instability mode for the aft dome. For the linear bifurcation and nonlinear analyses, the results show that accurate predictions of the response of the shell generally require a large-scale, high fidelity finite-element model. Results are also presented that show that the SLWT LO2 tank can support loads in excess of approximately 1.9 times the values of the operational loads considered.

Residential Variable-Capacity Heat Pumps Sized to Heating Loads

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munk, Jeffrey D.; Jackson, Roderick K.; Odukomaiya, Adewale

2014-01-01

Variable capacity heat pumps are an emerging technology offering significant energy savings potential and improved efficiency. With conventional single-speed systems, it is important to appropriately size heat pumps for the cooling load as over-sizing would result in cycling and insufficient latent capacity required for humidity control. These appropriately sized systems are often under-sized for the heating load and require inefficient supplemental electric resistance heat to meet the heating demand. Variable capacity heat pumps address these shortcomings by providing an opportunity to intentionally size systems for the dominant heating season load without adverse effects of cycling or insufficient dehumidification in themore » cooling season. This intentionally-sized system could result in significant energy savings in the heating season, as the need for inefficient supplemental electric resistance heat is drastically reduced. This is a continuation of a study evaluating the energy consumption of variable capacity heat pumps installed in two unoccupied research homes in Farragut, a suburb of Knoxville, Tennessee. In this particular study, space conditioning systems are intentionally sized for the heating season loads to provide an opportunity to understand and evaluate the impact this would have on electric resistance heat use and dehumidification. The results and conclusions drawn through this research are valid and specific for portions of the Southeastern and Midwestern United States falling in the mixed-humid climate zone. While other regions in the U.S. do not experience this type of climate, this work provides a basis for, and can help understand the implications of other climate zones on residential space conditioning energy consumption. The data presented here will provide a framework for fine tuning residential building EnergyPlus models that are being developed.« less

Characterizing the Collagen Fiber Orientation in Pericardial Leaflets Under Mechanical Loading Conditions

PubMed Central

Alavi, S. Hamed; Ruiz, Victor; Krasieva, Tatiana; Botvinick, Elliot L.; Kheradvar, Arash

2014-01-01

When implanted inside the body, bioprosthetic heart valve leaflets experience a variety of cyclic mechanical stresses such as shear stress due to blood flow when the valve is open, flexural stress due to cyclic opening and closure of the valve, and tensile stress when the valve is closed. These types of stress lead to a variety of failure modes. In either a natural valve leaflet or a processed pericardial tissue leaflet, collagen fibers reinforce the tissue and provide structural integrity such that the very thin leaflet can stand enormous loads related to cyclic pressure changes. The mechanical response of the leaflet tissue greatly depends on collagen fiber concentration, characteristics, and orientation. Thus, understating the microstructure of pericardial tissue and its response to dynamic loading is crucial for the development of more durable heart valve, and computational models to predict heart valves’ behavior. In this work, we have characterized the 3D collagen fiber arrangement of bovine pericardial tissue leaflets in response to a variety of different loading conditions under Second-Harmonic Generation Microscopy. This real-time visualization method assists in better understanding of the effect of cyclic load on collagen fiber orientation in time and space. PMID:23180029

An Experimental Investigation of Silicone-to-Metal Bond Strength in Composite Space Docking System Seals

NASA Technical Reports Server (NTRS)

Gaier, James R.; Siamidis, John; Larkin, Elizabeth M. G.

2010-01-01

The National Aeronautics and Space Administration (NASA) is currently developing a new universal docking mechanism for future space exploration missions called the Low Impact Docking System (LIDS). A candidate LIDS main interface seal design is a composite assembly of silicone elastomer seals vacuum molded into grooves in an electroless nickel plated aluminum retainer. The strength of the silicone-tometal bond is a critical consideration for the new system, especially due to the presence of small areas of disbond created during the molding process. In the work presented herein, seal-to-retainer bonds of subscale seal specimens with different sizes of intentional disbond were destructively tensile tested. Nominal specimens without intentional disbonds were also tested. Tension was applied either uniformly on the entire seal circumference or locally in one short circumferential length. Bond failure due to uniform tension produced a wide scatter of observable failure modes and measured load-displacement behaviors. Although the preferable failure mode for the seal-to-retainer bond is cohesive failure of the elastomer material, the dominant observed failure mode under the uniform loading condition was found to be the less desirable adhesive failure of the bond in question. The uniform tension case results did not show a correlation between disbond size and bond strength. Localized tension was found to produce failure either as immediate tearing of the elastomer material outside the bond region or as complete peel-out of the seal in one piece. The obtained results represent a valuable benchmark for comparison in the future between adhesion loads under various separation conditions and composite seal bond strength.

Cardiovascular function in space flight

NASA Technical Reports Server (NTRS)

Nicogossian, A. E.; Charles, J. B.; Bungo, M. W.; Leach-Huntoon, C. S.

1990-01-01

Postflight orthostatic intolerance and cardiac hemodynamics associated with manned space flight have been investigated on seven STS missions. Orthostatic heart rates appear to be influenced by the mission duration. The rates increase during the first 7-10 days of flight and recover partially after that. Fluid loading is used as a countermeasure to the postflight orthostatic intolerance. The carotid baroreceptor function shows only slight responsiveness to orthostatic stimulation. Plots of the baroreceptor function are presented. It is concluded that an early adaptation to the space flight conditions involves a fluid shift and that the subsequent alterations in the neutral controlling mechanisms contribute to the orthoststic intolerance.

Ice/frost/debris assessment for space shuttle Mission STS-32 (61-C)

NASA Technical Reports Server (NTRS)

Stevenson, Charles G.; Katnik, Gregory N.; Speece, Robert F.

1986-01-01

An Ice/Frost/Debris assessment was conducted for Space Shuttle Mission STS-32 (61-C). This assessment begins with debris inspections of the flight elements and launch facilities before and after launch. Ice/Frost formations are calculated during cryogenic loading of the external tank followed by an on-pad assessment of the Shuttle vehicle and pad at T-3 hours in the countdown. High speed films are reviewed after launch to identify Ice/Frost/Debris sources and investigate potential vehicle damage. The Ice/Frost/Debris conditions and their effects on the Space Shuttle are documented.

Thermal storage for electric utilities

NASA Technical Reports Server (NTRS)

Swet, C. J.; Masica, W. J.

1977-01-01

Applications of the thermal energy storage (TES) principle (storage of sensible heat or latent heat, or heat storage in reversible chemical reactions) in power systems are evaluated. Load leveling behind the meter, load following at conventional thermal power plants, solar thermal power generation, and waste heat utilization are the principal TES applications considered. Specific TES examples discussed include: storage heaters for electric-resistance space heating, air conditioning TES in the form of chilled water or eutectic salt baths, hot water TES, and trans-seasonal storage in heated water in confined aquifers.

Bivariate extreme value distributions

NASA Technical Reports Server (NTRS)

Elshamy, M.

1992-01-01

In certain engineering applications, such as those occurring in the analyses of ascent structural loads for the Space Transportation System (STS), some of the load variables have a lower bound of zero. Thus, the need for practical models of bivariate extreme value probability distribution functions with lower limits was identified. We discuss the Gumbel models and present practical forms of bivariate extreme probability distributions of Weibull and Frechet types with two parameters. Bivariate extreme value probability distribution functions can be expressed in terms of the marginal extremel distributions and a 'dependence' function subject to certain analytical conditions. Properties of such bivariate extreme distributions, sums and differences of paired extremals, as well as the corresponding forms of conditional distributions, are discussed. Practical estimation techniques are also given.

Instrumentation and Methods to Measure Dynamic Forces During Exercise Using the Horizontal Exercise Machine

NASA Technical Reports Server (NTRS)

Figueroa, Fernando

1999-01-01

It is hypothesized that bone loss experienced by astronauts in zero gravity conditions may be curtailed by appropriate exercise. According to Wolf's law, bone regenerates when muscles produce stresses by pulling on the bone during daily activity and/or exercise on Earth. To use this theory to prevent or decrease bone loss, one needs to quantify musculoskeletal loads and relate them to bone density changes. In the context of the space program, it is desirable to determine musculoskeletal loads during exercise so that one may make similar measurements on Earth and in space. In this manner, load measurements on Earth may be used as reference to generate similar loads during exercise in space. A research project to investigate the effects of high-resistive exercise to decrease bone density loss underzero-gravity conditions is being carried out in Life Sciences Research Laboratories at NASA JSC. The project consists of a bed-rest study whereby subjects remain in horizontal position for seventeen weeks. During the study, a subset of those subjects executes a regime of resistive exercises in the horizontal exercise machine (HEM). The HEM was designed so that subjects remain horizontal while exercising to minimize gravity loading even during exercise. Bone density of each subject is measured throughout the duration of their participation. The objective of the study is to determine if the resistive exercises are effective in diminishing or eliminating bone loss. My participation in this project relates to instrumentation, measurement, and processing of signals from displacement sensors (optical encoders) and load-cells. Measurement of displacements will be used to determine the motion of the body during exercise, and load measurements will be used (along with displacement data) to determine forces and torques exerted on each section of the body during exercise. Further, I have assisted in specifying new sensors to be added to the HEM and to a new prototype resistive exercise machine called the Interim Resistive Exercise Device (IRED). New load cells and encoders should be mounted in these devices to obtain more complete kineto-dynamic information. This report includes a description of the instrumentation that was built to perform measurements in the HEM and the IRED, along with the software that was developed to collect the measurements. It also includes examples of measurements taken in the HEM. Finally, a plan is laid out that describes how these measurements may be used to determine forces exerted by muscles for each exercise.

Transient Pressure Test Article Test Program

NASA Technical Reports Server (NTRS)

Vibbart, Charles M.

1989-01-01

The Transient Pressure Test Article (TPTA) test program is being conducted at a new test facility located in the East Test Area at the National Aeronautics and Space Administration's (NASA's) Marshall Space Flight Center (MSFC) in Huntsville, Alabama. This facility, along with the special test equipment (STE) required for facility support, was constructed specifically to test and verify the sealing capability of the Redesigned Solid Rocket Motor (RSRM) field, igniter, and nozzle joints. The test article consists of full scale RSRM hardware loaded with inert propellant and assembled in a short stack configuration. The TPTA is pressurized by igniting a propellant cartridge capable of inducing a pressure rise rate which stimulates the ignition transient that occurs during launch. Dynamic loads are applied during the pressure cycle to simulate external tank attach (ETA) strut loads present on the ETA ring. Sealing ability of the redesigned joints is evaluated under joint movement conditions produced by these combined loads since joint sealing ability depends on seal resilience velocity being greater than gap opening velocity. Also, maximum flight dynamic loads are applied to the test article which is either pressurized to 600 psia using gaseous nitrogen (GN2) or applied to the test article as the pressure decays inside the test article on the down cycle after the ignition transient cycle. This new test facility is examined with respect to its capabilities. In addition, both the topic of test effectiveness versus space vehicle flight performance and new aerospace test techniques, as well as a comparison between the old SRM design and the RSRM are presented.

Evaluating Moisture Control of Variable-Capacity Heat Pumps in Mechanically Ventilated, Low-Load Homes in Climate Zone 2A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Eric; Withers, Chuck; McIlvaine, Janet

The well-sealed, highly insulated building enclosures constructed by today's home building industry coupled with efficient lighting and appliances are achieving significantly reduced heating and cooling loads. These low-load homes can present a challenge when selecting appropriate space-conditioning equipment. Conventional, fixed-capacity heating and cooling equipment is often oversized for small homes, causing increased first costs and operating costs. Even if fixed-capacity equipment can be properly specified for peak loads, it remains oversized for use during much of the year. During these part-load cooling hours, oversized equipment meets the target dry-bulb temperatures very quickly, often without sufficient opportunity for moisture control. Themore » problem becomes more acute for high-performance houses in humid climates when meeting ASHRAE Standard 62.2 recommendations for wholehouse mechanical ventilation.« less

Pretest Plan for a Quarter Scale AFT Segment of the SRB Filament Wound Case in the NSWC Hydroballistics Facility. [space shuttle boosters

NASA Technical Reports Server (NTRS)

Adoue, J. A.

1984-01-01

In support of preflight design loads definition, preliminary water impact scale model are being conducted of space shuttle rocket boosters. The model to be used as well as the instrumentation, test facilities, and test procedures are described for water impact tests being conducted at test conditions to simulate full-scale initial impact at vertical velocities from 65 to 85 ft/sec. zero horizontal velocity, and angles of 0,5, and 10 degrees.

Turbine blade unsteady aerodynamic loading and heat transfer

NASA Astrophysics Data System (ADS)

Johnston, David Alan

Stator indexing to minimize the unsteady aerodynamic loading of closely spaced airfoil rows in turbomachinery is a new technique for the passive control of flow-induced vibrations. This technique, along with the effects of steady blade loading, were studied by means of experiments performed in a two-stage low-speed research turbine. With the second vane row fixed, the inlet vane row was indexed to six positions over one vane-pitch cycle for a range of stage loadings. The aerodynamic forcing function to the first-stage rotor was measured in the rotating reference frame, with the resulting rotor blade unsteady aerodynamic response quantified by rotor blades instrumented with dynamic pressure transducers. Reductions in the unsteady lift magnitude were achieved at all turbine operating conditions, with attenuation ranging from 37% to 74% of the maximum unsteady lift. Additionally, in complementary experiments, the effects of stator indexing and steady blade loading on the unsteady heat transfer of the first- and second-stage rotors was studied for the design and highest blade loading conditions using platinum-film heat gages. The attenuation of unsteady heat transfer coefficient was blade-loading dependent and location dependent along the chord and span, ranging 10% to 90% of maximum. Due to the high degree of location dependence of attenuation, stator indexing is therefore best suited to minimize unsteady heat transfer in local hot spots of the blade rather than the blade as a whole.

Probabilistic load simulation: Code development status

NASA Astrophysics Data System (ADS)

Newell, J. F.; Ho, H.

1991-05-01

The objective of the Composite Load Spectra (CLS) project is to develop generic load models to simulate the composite load spectra that are included in space propulsion system components. The probabilistic loads thus generated are part of the probabilistic design analysis (PDA) of a space propulsion system that also includes probabilistic structural analyses, reliability, and risk evaluations. Probabilistic load simulation for space propulsion systems demands sophisticated probabilistic methodology and requires large amounts of load information and engineering data. The CLS approach is to implement a knowledge based system coupled with a probabilistic load simulation module. The knowledge base manages and furnishes load information and expertise and sets up the simulation runs. The load simulation module performs the numerical computation to generate the probabilistic loads with load information supplied from the CLS knowledge base.

A 3-D Magnetic Analysis of a Stirling Convertor Linear Alternator Under Load

NASA Technical Reports Server (NTRS)

Geng, Steven M.; Schwarze, Gene E.; Niedra, Janis M.; Regan, Timothy F.

2001-01-01

The NASA Glenn Research Center (GRC), the Department of Energy (DOE), and the Stirling Technology Company (STC) are developing Stirling convertors for Stirling Radioisotope Power Systems (SRPS) to provide electrical power for future NASA deep space missions. STC is developing the 55-We Technology Demonstration Convertor (TDC) under contract to DOE. Of critical importance to the successful development of the Stirling convertor for space power applications is the development of a lightweight and highly efficient linear alternator. This paper presents a 3-dimensional finite element method (FEM) approach for evaluating Stirling convertor linear alternators. The model extends a magnetostatic analysis previously reported at the 35th Intersociety Energy Conversion Engineering Conference (IECEC) to include the effects of the load current. STC's 55-We linear alternator design was selected to validate the model. Spatial plots of magnetic field strength (H) are presented in the region of the exciting permanent magnets. The margin for permanent magnet demagnetization is calculated at the expected magnet operating temperature for the near earth environment and for various average magnet temperatures. These thermal conditions were selected to represent a worst-case condition for the planned deep space missions. This paper presents plots that identify regions of high H where the potential to alter the magnetic moment of the magnets exists.

Time-Accurate Unsteady Pressure Loads Simulated for the Space Launch System at Wind Tunnel Conditions

NASA Technical Reports Server (NTRS)

Alter, Stephen J.; Brauckmann, Gregory J.; Kleb, William L.; Glass, Christopher E.; Streett, Craig L.; Schuster, David M.

2015-01-01

A transonic flow field about a Space Launch System (SLS) configuration was simulated with the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics (CFD) code at wind tunnel conditions. Unsteady, time-accurate computations were performed using second-order Delayed Detached Eddy Simulation (DDES) for up to 1.5 physical seconds. The surface pressure time history was collected at 619 locations, 169 of which matched locations on a 2.5 percent wind tunnel model that was tested in the 11 ft. x 11 ft. test section of the NASA Ames Research Center's Unitary Plan Wind Tunnel. Comparisons between computation and experiment showed that the peak surface pressure RMS level occurs behind the forward attach hardware, and good agreement for frequency and power was obtained in this region. Computational domain, grid resolution, and time step sensitivity studies were performed. These included an investigation of pseudo-time sub-iteration convergence. Using these sensitivity studies and experimental data comparisons, a set of best practices to date have been established for FUN3D simulations for SLS launch vehicle analysis. To the author's knowledge, this is the first time DDES has been used in a systematic approach and establish simulation time needed, to analyze unsteady pressure loads on a space launch vehicle such as the NASA SLS.

The Liquid Nitrogen System for Chamber A: A Change from Original Forced Flow Design to a Natural Flow (Thermo Siphon) System

NASA Technical Reports Server (NTRS)

Homan, Jonathan; Montz, Michael; Sidi-Yekhlef, Ahmed; Ganni, Venkatarao (Rao); Knudsen, Peter; Garcia, Sam; Linza, Robert; Meagher, Daniel; Lauterbauch, John

2008-01-01

NASA Johnson Space Center (JSC) in Houston is currently supplementing its 20K helium refrigeration system to meet the new requirements for testing the James Web Space Telescope in the environmental control Chamber-A (65 dia x 120 high) in Building 32. The new system is required to meet the various operating modes which include a high 20K heat load, a required temperature stability at the load, rapid (but controlled) cool down and warm up and bake out of the chamber. This paper will present the proposed modifications to the existing helium system(s) to incorporate the new requirements and the integration of the new helium refrigerator with the existing two 3.5KW 20K helium refrigerators. In addition, the floating pressure process control philosophy to achieve high efficiency over the operating range (40% to 100% of the refrigeration system capacity), and the required temperature stability of +/- 0.25 K at the load will be discussed. The refrigeration systems ability to naturally seek the operating conditions under various loads and thus minimizing operator involvement and the over all improvements to the system operability and the reliability will be explained.

CFD Applications in Support of the Space Shuttle Risk Assessment

NASA Technical Reports Server (NTRS)

Baum, Joseph D.; Mestreau, Eric; Luo, Hong; Sharov, Dmitri; Fragola, Joseph; Loehner, Rainald; Cook, Steve (Technical Monitor)

2000-01-01

The paper describes a numerical study of a potential accident scenario of the space shuttle, operating at the same flight conditions as flight 51L, the Challenger accident. The interest in performing this simulation is derived by evidence that indicates that the event itself did not exert large enough blast loading on the shuttle to break it apart. Rather, the quasi-steady aerodynamic loading on the damaged, unbalance vehicle caused the break-up. Despite the enormous explosive potential of the shuttle total fuel load (both liquid and solid), the post accident explosives working group estimated the maximum energy involvement to be equivalent to about five hundreds of pounds of TNT. This understanding motivated the simulation described here. To err on the conservative side, we modeled the event as an explosion, and used the maximum energy estimate. We modeled the transient detonation of a 500 lbs spherical charge of TNT, placed at the main engine, and the resulting blast wave propagation about the complete stack. Tracking of peak pressures and impulses at hundreds of locations on the vehicle surface indicate that the blast load was insufficient to break the vehicle, hence demonstrating likely crew survivability through such an event.

Effects of Initial Geometric Imperfections On the Non-Linear Response of the Space Shuttle Superlightweight Liquid-Oxygen Tank

NASA Technical Reports Server (NTRS)

Nemeth, Michael P.; Young, Richard D.; Collins, Timothy J.; Starnes, James H., Jr.

2002-01-01

The results of an analytical study of the elastic buckling and nonlinear behavior of the liquid-oxygen tank for the new Space Shuttle superlightweight external fuel tank are presented. Selected results that illustrate three distinctly different types of non-linear response phenomena for thin-walled shells which are subjected to combined mechanical and thermal loads are presented. These response phenomena consist of a bifurcation-type buckling response, a short-wavelength non-linear bending response and a non-linear collapse or "snap-through" response associated with a limit point. The effects of initial geometric imperfections on the response characteristics are emphasized. The results illustrate that the buckling and non-linear response of a geometrically imperfect shell structure subjected to complex loading conditions may not be adequately characterized by an elastic linear bifurcation buckling analysis, and that the traditional industry practice of applying a buckling-load knock-down factor can result in an ultraconservative design. Results are also presented that show that a fluid-filled shell can be highly sensitive to initial geometric imperfections, and that the use a buckling-load knock-down factor is needed for this case.

14 CFR 25.407 - Trim tab effects.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Trim tab effects. 25.407 Section 25.407... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Control Surface and System Loads § 25.407 Trim tab effects. The effects of trim tabs on the control surface design conditions must be accounted for only where the...

14 CFR 25.407 - Trim tab effects.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Trim tab effects. 25.407 Section 25.407... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Control Surface and System Loads § 25.407 Trim tab effects. The effects of trim tabs on the control surface design conditions must be accounted for only where the...

Application of Video Image Correlation Techniques to the Space Shuttle External Tank Foam Materials

NASA Technical Reports Server (NTRS)

Hilburger, Mark W.; Nemeth, Michael P.

2005-01-01

Results that illustrate the use of a video-image-correlation-based displacement and strain measurement system to assess the effects of material nonuniformities on the behavior of the sprayed-on foam insulation (SOFI) used for the thermal protection system on the Space Shuttle External Tank are presented. Standard structural verification specimens for the SOFI material with and without cracks and subjected to mechanical or thermal loading conditions were tested. Measured full-field displacements and strains are presented for selected loading conditions to illustrate the behavior of the foam and the viability of the measurement technology. The results indicate that significant strain localization can occur in the foam because of material nonuniformities. In particular, elongated cells in the foam can interact with other geometric or material discontinuities in the foam and develop large-magnitude localized strain concentrations that likely initiate failures. Furthermore, some of the results suggest that continuum mechanics and linear elastic fracture mechanics might not adequately represent the physical behavior of the foam, and failure predictions based on homogeneous linear material models are likely to be inadequate.

Application of Video Image Correlation Techniques to the Space Shuttle External Tank Foam Materials

NASA Technical Reports Server (NTRS)

Hilburger, Mark W.; Nemeth, Michael P.

2006-01-01

Results that illustrate the use of a video-image-correlation-based displacement and strain measurement system to assess the effects of material nonuniformities on the behavior of the sprayed-on foam insulation (SOFI) used for the thermal protection system on the Space Shuttle External Tank are presented. Standard structural verification specimens for the SOFI material with and without cracks and subjected to mechanical or thermal loading conditions were tested. Measured full-field displacements and strains are presented for selected loading conditions to illustrate the behavior of the foam and the viability of the measurement technology. The results indicate that significant strain localization can occur in the foam because of material nonuniformities. In particular, elongated cells in the foam can interact with other geometric or material discontinuities in the foam and develop large-magnitude localized strain concentrations that likely initiate failures. Furthermore, some of the results suggest that continuum mechanics and linear elastic fracture mechanics might not adequately represent the physical behavior of the foam, and failure predictions based on homogeneous linear material models are likely to be inadequate.

Global Comparison of CFD and Wind-Tunnel-Derived Force and Moment Databases for the Space Launch System

NASA Technical Reports Server (NTRS)

Hemsch, Michael J.

2016-01-01

Recently a very large (739 runs) collection of high-fidelity RANS CFD solutions was obtained for Space Launch System ascent aerodynamics for the vehicle to be used for the first exploratory (unmanned) mission (EM-1). The extensive computations, at full-scale conditions, were originally developed to obtain detailed line and protuberance loads and surface pressures for venting analyses. The line loads were eventually integrated for comparison of the resulting forces and moments to the database that was derived from wind tunnel tests conducted at sub-scale conditions. The comparisons presented herein cover the ranges 0.5 < or = M(infinity) < or = 5, -6deg < or = alpha < or = 6deg, and -6deg < or = beta < or = 6deg. For detailed comparisons, slender-body-theory-based component build-up aero models from missile aerodynamics are used. The differences in the model fit coefficients are shown to be relatively small except for the low supersonic Mach number range, 1.1 < or = M(infinity) < or = 2.0. The analysis is intended to support process improvement and development of uncertainty models.

Debris/ice/TPS assessment and photographic analysis for Shuttle Mission STS-33R

NASA Technical Reports Server (NTRS)

Stevenson, Charles G.; Katnik, Gregory N.; Higginbotham, Scott A.

1989-01-01

A debris/ice/Thermal Protection System (TPS) assessment and photographic analysis was conducted for Space Shuttle Mission STS-33R. Debris inspections of the flight elements and launch pad are performed before and after launch. Ice/frost conditions on the external tank are assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography is analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the debris/ice/TPS conditions and photographic analysis of Mission STS-33R, and their overall effect on the Space Shuttle Program.

Debris/ice/TPS assessment and photographic analysis for shuttle mission STS-31R

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.; Higginbotham, Scott A.; Davis, J. Bradley

1990-01-01

A Debris/Ice/Thermal Protection System (TPS) assessment and photographic analysis was conducted for Space Shuttle Mission STS-31R. Debris inspections of the flight elements and launch pad are performed before and after launch. Ice/frost conditions on the External Tank are assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography is analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. The debris/ice/TPS conditions and photographic analysis of Mission STS-31R, is presented along with their overall effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-102

NASA Technical Reports Server (NTRS)

Rivera, Jorge E.; Kelly, J. David (Technical Monitor)

2001-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-102. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch were analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or inflight anomalies. This report documents the debris/ice /thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-102 and the resulting effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Photographic Analysis for Shuttle Mission STS-38

NASA Technical Reports Server (NTRS)

Higginbotham, Scott A.; Davis, J. Bradley

1991-01-01

A debris/ice/TPS assessment and photographic analysis was conducted for the Space Shuttle Mission STS-38. Debris inspection of the flight elements and launch pad were performed before and after launch. Ice/frost conditions on the external tank were assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography was analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. The debris/ice/TPS conditions and photographic analysis of Mission STS-38, and their overall effect on the Space Shuttle Program are documented.

Debris/ice/TPS assessment and photographic analysis of shuttle mission STS-48

NASA Technical Reports Server (NTRS)

Higginbotham, Scott A.; Davis, J. Bradley

1991-01-01

A Debris/Ice/TPS assessment and photographic analysis was conducted for Space Shuttle Mission STS-48. Debris inspection of the flight elements and launch pad were performed before and after launch. Ice/frost conditions on the External Tank were assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography was analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. The debris/ice/TPS conditions and photographic analysis of Mission STS-48 are documented, along with their overall effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Photographic Analysis for Shuttle Mission STS-37

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.; Higginbotham, Scott A.; Davis, J. Bradley

1991-01-01

A Debris/Ice/TPS assessment and photographic analysis was conducted for Space Shuttle Mission STS-37. Debris inspections of the flight elements and launch pad were performed before and after launch. Ice/frost conditions on the External Tank were assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography of launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or inflight anomalies. The debris/ice/TPS conditions and photographic analysis of Mission STS-37 are documented, along with their overall effect on the Space Shuttle Program.

Debris/ice/TPS assessment and photographic analysis for Shuttle Mission STS-36

NASA Technical Reports Server (NTRS)

Stevenson, Charles G.; Katnik, Gregory N.; Higginbotham, Scott A.

1990-01-01

A Debris/Ice/TPS (Thermal Protection System) assessment and photographic analysis was conducted for Space Shuttle Mission STS-36. Debris inspections of the flight elements and launch pad are performed before and after launch. Ice/frost conditions on the External Tank are assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography is analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. The debris/ice/TPS conditions and photographic analysis of Mission STS-36, and their overall effect on the Space Shuttle Program are documented.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-106

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.; Kelley, J. David (Technical Monitor)

2000-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-106. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and in-flight anomalies. This report documents the ice/debris/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-106 and the resulting effect on the Space Shuttle Program.

Debris/ice/TPS assessment and photographic analysis for Shuttle Mission STS-34

NASA Technical Reports Server (NTRS)

Stevenson, Charles G.; Katnik, Gregory N.; Higginbotham, Scott A.

1989-01-01

A Debris/Ice/Thermal Protection System (TPS) assessment and photographic analysis was conducted for Space Shuttle Mission STS-34. Debris inspections of the flight elements and launch pad are performed before and after launch. Ice/frost conditions on the External Tank are assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography is analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. The debris/ice/TPS conditions and photographic analysis of Mission STS-34, and their overall effect on the Space Shuttle Program are documented.

Debris/Ice/TPS Assessment and Photographic Analysis for Shuttle Mission STS-41

NASA Technical Reports Server (NTRS)

Higginbotham, Scott A.; Davis, J. Bradley

1990-01-01

A Debris/Ice/Thermal Protection System (TPS) assessment and photographic analysis was conducted for Space Shuttle Mission STS-41. Debris inspections of the flight elements and launch pad were performed before and after launch. Ice/frost conditions on the External Tank were assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography was analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. Documented here are the debris/ice/TPS conditions and photographic analysis of Mission STS-41, and their overall effect on the Space Shuttle Program.

Reflectivity of the AL-N coating: results of mechanical and environmental tests

NASA Astrophysics Data System (ADS)

Anisimov, Vladimir P.; Anisimova, Irina A.; Kashirin, Victor A.; Moldosanov, Kamil A.; Skrynnikov, Alexander M.

2002-09-01

This paper concerns a behavior of the total hemispherical reflectance (THR) of the Al-N coating in the course of mechanical and environmental tests. The Al-N coating has been designed to reduce the stray sunlight background in the satellite-borne optical instruments and charge-particles-analyzing apparatus operating in open space under intensive solar radiation. Usually, this problem arises when a density of instruments installed on the satellite is high and it is difficult to avoid getting to instrument the light reflected by neighboring devices. Resolution of this problem is also important in connection with development of the extra-atmosphere Far UV astronomy. The THR measurement results are presented for 10 wavelengths wihtin a range from 400 to 927 nm, and also at 121.6 nm, the most intensive line of the solar UV spectrum able to result in considerable contribution to the detector noise in space devices. The samples of the Al-N coating were exposed to standard mechanical loads including the vibratory loads, linear overloads, and impacts, to which the space equipment may be subjected when shipping to the space-vehicle launching site and also when lauching. The samples were also exposed to environmental tests simulating the vacuum, humidity, and cyclic temperature conditions, which may influence the space instruments while shipping, storing, launching, in flight, and under operating conditions. The THR measurements of the samples were made following exposure to each test. The THRs of tested samples at the wavelength of 121.6 nm were as low as 1.5-2%.

Simplified Space Conditioning in Low-Load Homes: Results from Pittsburgh, Pennsylvania, New Construction Unoccupied Test House

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poerschke, Andrew; Stecher, Dave

2014-06-01

Field testing was performed in a new construction unoccupied test house in Pittsburgh, PA. Four air-based heating, ventilation, and air conditioning distribution systems—a typical airflow ducted system to the bedrooms, a low airflow ducted system to the bedrooms, a system with transfer fans to the bedrooms, and a system with no ductwork to the bedrooms—were evaluated during heating, cooling, and midseason conditions. The relative ability of each system was assessed with respect to relevant Air Conditioning Contractors of America and ASHRAE standards for house temperature uniformity and stability, respectively.

Simplified Space Conditioning in Low-Load Homes: Results from Pittsburgh, Pennsylvania, New Construction Unoccupied Test House

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poerschke, A.; Stecher, D.

2014-06-01

Field testing was performed in a new construction unoccupied test house in Pittsburgh, Pennsylvania. Four air-based heating, ventilation, and air conditioning distribution systems--a typical airflow ducted system to the bedrooms, a low airflow ducted system to the bedrooms, a system with transfer fans to the bedrooms, and a system with no ductwork to the bedrooms--were evaluated during heating, cooling, and midseason conditions. The relative ability of each system was assessed with respect to relevant Air Conditioning Contractors of America and ASHRAE standards for house temperature uniformity and stability, respectively.

Controllability of Free-piston Stirling Engine/linear Alternator Driving a Dynamic Load

NASA Technical Reports Server (NTRS)

Kankam, M. David; Rauch, Jeffrey S.

1994-01-01

This paper presents the dynamic behavior of a Free-Piston Stirling Engine/linear alternator (FPSE/LA) driving a single-phase fractional horse-power induction motor. The controllability and dynamic stability of the system are discussed by means of sensitivity effects of variations in system parameters, engine controller, operating conditions, and mechanical loading on the induction motor. The approach used expands on a combined mechanical and thermodynamic formulation employed in a previous paper. The application of state-space technique and frequency domain analysis enhances understanding of the dynamic interactions. Engine-alternator parametric sensitivity studies, similar to those of the previous paper, are summarized. Detailed discussions are provided for parametric variations which relate to the engine controller and system operating conditions. The results suggest that the controllability of a FPSE-based power system is enhanced by proper operating conditions and built-in controls.

Sensitivity of Space Launch System Buffet Forcing Functions to Buffet Mitigation Options

NASA Technical Reports Server (NTRS)

Piatak, David J.; Sekula, Martin K.; Rausch, Russ D.

2016-01-01

Time-varying buffet forcing functions arise from unsteady aerodynamic pressures and are one of many load environments, which contribute to the overall loading condition of a launch vehicle during ascent through the atmosphere. The buffet environment is typically highest at transonic conditions and can excite the vehicle dynamic modes of vibration. The vehicle response to these buffet forcing functions may cause high structural bending moments and vibratory environments, which can exceed the capabilities of the structure, or of vehicle components such as payloads and avionics. Vehicle configurations, protuberances, payload fairings, and large changes in stage diameter can trigger undesirable buffet environments. The Space Launch System (SLS) multi-body configuration and its structural dynamic characteristics presented challenges to the load cycle design process with respect to buffet-induced loads and responses. An initial wind-tunnel test of a 3-percent scale SLS rigid buffet model was conducted in 2012 and revealed high buffet environments behind the booster forward attachment protuberance, which contributed to reduced vehicle structural margins. Six buffet mitigation options were explored to alleviate the high buffet environments including modified booster nose cones and fences/strakes on the booster and core. These studies led to a second buffet test program that was conducted in 2014 to assess the ability of the buffet mitigation options to reduce buffet environments on the vehicle. This paper will present comparisons of buffet forcing functions from each of the buffet mitigation options tested, with a focus on sectional forcing function rms levels within regions of the vehicle prone to high buffet environments.

Performance Analysis of a Modular Small-Diamter Air Distribution System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poerschke, Andrew; Rudd, Armin

2016-03-01

This report investigates the feasibility of using a home-run manifold small-diameter duct system to provide space conditioning air to individual thermal zones in a low-load home. This compact layout allows duct systems to be brought easily within conditioned space via interior partition walls. Centrally locating the air handler unit in the house significantly reduces duct lengths. The plenum box is designed so that each connected duct receives an equal amount of airflow, regardless of the duct position on the box. Furthermore, within a reasonable set of length restrictions, each duct continues to receive similar airflow. The design method uses anmore » additive approach to reach the total needed zonal airflow. Once the cubic feet per minute needed to satisfy the thermal load of a zone has been determined, the total number of duct runs to a zone can be calculated by dividing the required airflow by the standard airflow from each duct. The additive approach greatly simplifies the design effort and reduces the potential for duct design mistakes to be made. Measured results indicate that this plenum design can satisfy the heating load. However, the total airflow falls short of satisfying the cooling load in a hypothetical building. Static pressure inside the plenum box of 51.5 Pa limited the total airflow of the attached mini-split heat pump blower, thus limiting the total thermal capacity. Fan energy consumption is kept to 0.16 to 0.22 watt/CFM by using short duct runs and smooth duct material.« less

Comparison of Gait During Treadmill Exercise While Supine in Lower Body Negative Pressure (LBNP), Supine with Bungee Resistance and Upright in Normal Gravity

NASA Technical Reports Server (NTRS)

Boda, Wanda; Hargens, Alan R.; Aratow, Michael; Ballard, Richard E.; Hutchinson, Karen; Murthy, Gita; Campbell, James

1994-01-01

The purpose of this study is to compare footward forces, gait kinematics, and muscle activation patterns (EMG) generated during supine treadmill exercise against LBNP with the same parameters during supine bungee resistance exercise and upright treadmill exercise. We hypothesize that the three conditions will be similar. These results will help validate treadmill exercise during LBNP as a viable technique to simulate gravity during space flight. We are evaluating LBNP as a means to load the musculoskeletal and cardiovascular systems without gravity. Such loading should help prevent physiologic deconditioning during space flight. The best ground-based simulation of LBNP treadmill exercise in microgravity is supine LBNP treadmill exercise on Earth because the supine footward force vector is neither directed nor supplemented by Earth's gravity.

Thermo-mechanical Properties of Upper Jurassic (Malm) Carbonate Rock Under Drained Conditions

NASA Astrophysics Data System (ADS)

Pei, Liang; Blöcher, Guido; Milsch, Harald; Zimmermann, Günter; Sass, Ingo; Huenges, Ernst

2018-01-01

The present study aims to quantify the thermo-mechanical properties of Neuburger Bankkalk limestone, an outcrop analog of the Upper Jurassic carbonate formation (Germany), and to provide a reference for reservoir rock deformation within future enhanced geothermal systems located in the Southern German Molasse Basin. Experiments deriving the drained bulk compressibility C were performed by cycling confining pressure p c between 2 and 50 MPa at a constant pore pressure p p of 0.5 MPa after heating the samples to defined temperatures between 30 and 90 °C. Creep strain was then measured after each loading and unloading stage, and permeability k was obtained after each creep strain measurement. The drained bulk compressibility increased with increasing temperature and decreased with increasing differential pressure p d = p c - p p showing hysteresis between the loading and unloading stages above 30 °C. The apparent values of the indirectly calculated Biot coefficient α ind containing contributions from inelastic deformation displayed the same temperature and pressure dependencies. The permeability k increased immediately after heating and the creep rates were also temperature dependent. It is inferred that the alteration of the void space caused by temperature changes leads to the variation of rock properties measured under isothermal conditions while the load cycles applied under isothermal conditions yield additional changes in pore space microstructure. The experimental results were applied to a geothermal fluid production scenario to constrain drawdown and time-dependent effects on the reservoir, overall, to provide a reference for the hydromechanical behavior of geothermal systems in carbonate, and more specifically, in Upper Jurassic lithologies.

Space Shuttle Day-of-Launch Trajectory Design and Verification

NASA Technical Reports Server (NTRS)

Harrington, Brian E.

2010-01-01

A top priority of any launch vehicle is to insert as much mass into the desired orbit as possible. This requirement must be traded against vehicle capability in terms of dynamic control, thermal constraints, and structural margins. The vehicle is certified to a specific structural envelope which will yield certain performance characteristics of mass to orbit. Some envelopes cannot be certified generically and must be checked with each mission design. The most sensitive envelopes require an assessment on the day-of-launch. To further minimize vehicle loads while maximizing vehicle performance, a day-of-launch trajectory can be designed. This design is optimized according to that day s wind and atmospheric conditions, which will increase the probability of launch. The day-of-launch trajectory verification is critical to the vehicle's safety. The Day-Of-Launch I-Load Uplink (DOLILU) is the process by which the Space Shuttle Program redesigns the vehicle steering commands to fit that day's environmental conditions and then rigorously verifies the integrated vehicle trajectory's loads, controls, and performance. The Shuttle methodology is very similar to other United States unmanned launch vehicles. By extension, this method would be similar to the methods employed for any future NASA launch vehicles. This presentation will provide an overview of the Shuttle's day-of-launch trajectory optimization and verification as an example of a more generic application of dayof- launch design and validation.

A mathematical multiscale model of bone remodeling, accounting for pore space-specific mechanosensation.

PubMed

Pastrama, Maria-Ioana; Scheiner, Stefan; Pivonka, Peter; Hellmich, Christian

2018-02-01

While bone tissue is a hierarchically organized material, mathematical formulations of bone remodeling are often defined on the level of a millimeter-sized representative volume element (RVE), "smeared" over all types of bone microstructures seen at lower observation scales. Thus, there is no explicit consideration of the fact that the biological cells and biochemical factors driving bone remodeling are actually located in differently sized pore spaces: active osteoblasts and osteoclasts can be found in the vascular pores, whereas the lacunar pores host osteocytes - bone cells originating from former osteoblasts which were then "buried" in newly deposited extracellular bone matrix. We here propose a mathematical description which considers size and shape of the pore spaces where the biological and biochemical events take place. In particular, a previously published systems biology formulation, accounting for biochemical regulatory mechanisms such as the rank-rankl-opg pathway, is cast into a multiscale framework coupled to a poromicromechanical model. The latter gives access to the vascular and lacunar pore pressures arising from macroscopic loading. Extensive experimental data on the biological consequences of this loading strongly suggest that the aforementioned pore pressures, together with the loading frequency, are essential drivers of bone remodeling. The novel approach presented here allows for satisfactory simulation of the evolution of bone tissue under various loading conditions, and for different species; including scenarios such as mechanical dis- and overuse of murine and human bone, or in osteocyte-free bone. Copyright © 2017 Elsevier Inc. All rights reserved.

Progressive Damage and Failure Analysis of Composite Laminates

NASA Astrophysics Data System (ADS)

Joseph, Ashith P. K.

Composite materials are widely used in various industries for making structural parts due to higher strength to weight ratio, better fatigue life, corrosion resistance and material property tailorability. To fully exploit the capability of composites, it is required to know the load carrying capacity of the parts made of them. Unlike metals, composites are orthotropic in nature and fails in a complex manner under various loading conditions which makes it a hard problem to analyze. Lack of reliable and efficient failure analysis tools for composites have led industries to rely more on coupon and component level testing to estimate the design space. Due to the complex failure mechanisms, composite materials require a very large number of coupon level tests to fully characterize the behavior. This makes the entire testing process very time consuming and costly. The alternative is to use virtual testing tools which can predict the complex failure mechanisms accurately. This reduces the cost only to it's associated computational expenses making significant savings. Some of the most desired features in a virtual testing tool are - (1) Accurate representation of failure mechanism: Failure progression predicted by the virtual tool must be same as those observed in experiments. A tool has to be assessed based on the mechanisms it can capture. (2) Computational efficiency: The greatest advantages of a virtual tools are the savings in time and money and hence computational efficiency is one of the most needed features. (3) Applicability to a wide range of problems: Structural parts are subjected to a variety of loading conditions including static, dynamic and fatigue conditions. A good virtual testing tool should be able to make good predictions for all these different loading conditions. The aim of this PhD thesis is to develop a computational tool which can model the progressive failure of composite laminates under different quasi-static loading conditions. The analysis tool is validated by comparing the simulations against experiments for a selected number of quasi-static loading cases.

Failure tolerance strategy of space manipulator for large load carrying tasks

NASA Astrophysics Data System (ADS)

Chen, Gang; Yuan, Bonan; Jia, Qingxuan; Sun, Hanxu; Guo, Wen

2018-07-01

During the execution of large load carrying tasks in long term service, there is a notable risk of space manipulator suffering from locked-joint failure, thus space manipulator should be with enough failure tolerance performance. A research on evaluating failure tolerance performance and re-planning feasible task trajectory for space manipulator performing large load carrying tasks is conducted in this paper. The effects of locked-joint failure on critical performance(reachability and load carrying capacity) of space manipulator are analyzed at first. According to the requirements of load carrying tasks, we further propose a new concept of failure tolerance workspace with load carrying capacity(FTWLCC) to evaluate failure tolerance performance, and improve the classic A* algorithm to search the feasible task trajectory. Through the normalized FTWLCC and the improved A* algorithm, the reachability and load carrying capacity of the degraded space manipulator are evaluated, and the reachable and capable trajectory can be obtained. The establishment of FTWLCC provides a novel idea that combines mathematical statistics with failure tolerance performance to illustrate the distribution of load carrying capacity in three-dimensional space, so multiple performance indices can be analyzed simultaneously and visually. And the full consideration of all possible failure situations and motion states makes FTWLCC and improved A* algorithm be universal and effective enough to be appropriate for random joint failure and variety of requirement of large load carrying tasks, so they can be extended to other types of manipulators.

The Implications of Reduced Ground Reaction Forces During Space Flight for Bone Strains

NASA Technical Reports Server (NTRS)

Peterman, Marc M.; Hamel, Andrew J.; Sharkey, Neil A.; Piazza, Stephen J.; Cavanagh, Peter R.

1998-01-01

The specific mechanisms regulating bone mass are not known, but most investigators agree that bone maintenance is largely dependent upon mechanical demand and the resultant local bone strains. During space flight, bone loss such as that reported by LeBlanc et al. may result from failure to effectively load the skeleton and generate sufficient localized bone strains. In microgravity, a gravity replacement system can be used to tether an exercising subject to a treadmill. It follows that the ability to prevent bone loss is critically dependent upon the external ground reaction forces (GRFs) and skeletal loads imparted by the tethering system. To our knowledge, the loads during orbital flight have been measured only once (on STS 81). Based on these data and data from ground based experiments, it appears likely that interventions designed to prevent bone loss in micro-gravity generate GRFs substantially less than body weight. It is unknown to what degree reductions in external GRFs will affect internal bone strain and thus the bone maintenance response. To better predict the efficacy of treadmill exercise in micro-gravity we used a unique cadaver model to measure localized bone strains under conditions representative of those that might be produced by a gravity replacement system in space.

Acoustic performance of low pressure axial fan rotors with different blade chord length and radial load distribution

NASA Astrophysics Data System (ADS)

Carolus, Thomas

The paper examines the acoustic and aerodynamic performance of low-pressure axial fan rotors with a hub/tip ratio of 0.45. Six rotors were designed for the same working point by means of the well-known airfoil theory. The condition of an equilibrium between the static pressure gradient and the centrifugal forces is maintained. All rotors have unequally spaced blades to diminish tonal noise. The rotors are tested in a short cylindrical housing without guide vanes. All rotors show very similar flux-pressure difference characteristics. The peak efficiency and the noise performance is considerably influenced by the chosen blade design. The aerodynamically and acoustically optimal rotor is the one with the reduced load at the hub and increased load in the tip region under satisfied equilibrium conditions. It runs at the highest aerodynamic efficiency, and its noise spectrum is fairly smooth. The overall sound pressure level of this rotor is up to 8 dB (A) lower compared to the other rotors under consideration.

Physics based model for online fault detection in autonomous cryogenic loading system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kashani, Ali; Ponizhovskaya, Ekaterina; Luchinsky, Dmitry

2014-01-29

We report the progress in the development of the chilldown model for a rapid cryogenic loading system developed at NASA-Kennedy Space Center. The nontrivial characteristic feature of the analyzed chilldown regime is its active control by dump valves. The two-phase flow model of the chilldown is approximated as one-dimensional homogeneous fluid flow with no slip condition for the interphase velocity. The model is built using commercial SINDA/FLUINT software. The results of numerical predictions are in good agreement with the experimental time traces. The obtained results pave the way to the application of the SINDA/FLUINT model as a verification tool formore » the design and algorithm development required for autonomous loading operation.« less

Analysis and test for space shuttle propellant dynamics (1/10th scale model test results). Volume 2: 1/10th scale model test data

NASA Technical Reports Server (NTRS)

Berry, R. L.; Tegart, J. R.; Demchak, L. J.

1979-01-01

Thirty sets of test data selected from the 89 low-g aircraft tests flown by NASA KC-135 zero-g aircraft are listed in tables with their accompanying test conditions. The data for each test consists of the time history plots of digitalized data (in engineering units) and the time history plots of the load cell data transformed to the tank axis system. The transformed load cell data was developed for future analytical comparisons; therefore, these data were transformed and plotted from the time at which the aircraft Z axis acceleration passed through l-g. There are 14 time history plots per test condition. The contents of each plot is shown in a table.

Condition of cardiovascular systems of astronauts during flight of Soyuz orbital station

NASA Technical Reports Server (NTRS)

Degtyarev, V. A.; Popov, I. I.; Batenchuk-Tusko, T. V.; Kolmykova, N. D.; Lapshina, N. A.; Kirillova, Z. A.; Doroshev, V. G.; Kukushkin, Y. A.

1975-01-01

Extensive studies of blood circulation functions during manned space flight demonstrated a pronounced tendency toward an increase in minute volume of the blood and a decrease in pulse wave propagation rate. Individual blood circulation indices had large amplitude fluctuations. Physical work loads caused slow recovery of heart rate, arterial pressure and minute blood volume.

Comparative analysis on flexibility requirements of typical Cryogenic Transfer lines

NASA Astrophysics Data System (ADS)

Jadon, Mohit; Kumar, Uday; Choukekar, Ketan; Shah, Nitin; Sarkar, Biswanath

2017-04-01

The cryogenic systems and their applications; primarily in large Fusion devices, utilize multiple cryogen transfer lines of various sizes and complexities to transfer cryogenic fluids from plant to the various user/ applications. These transfer lines are composed of various critical sections i.e. tee section, elbows, flexible components etc. The mechanical sustainability (under failure circumstances) of these transfer lines are primary requirement for safe operation of the system and applications. The transfer lines need to be designed for multiple design constraints conditions like line layout, support locations and space restrictions. The transfer lines are subjected to single load and multiple load combinations, such as operational loads, seismic loads, leak in insulation vacuum loads etc. [1]. The analytical calculations and flexibility analysis using professional software are performed for the typical transfer lines without any flexible component, the results were analysed for functional and mechanical load conditions. The failure modes were identified along the critical sections. The same transfer line was then refurbished with the flexible components and analysed for failure modes. The flexible components provide additional flexibility to the transfer line system and make it safe. The results obtained from the analytical calculations were compared with those obtained from the flexibility analysis software calculations. The optimization of the flexible component’s size and selection was performed and components were selected to meet the design requirements as per code.

Techniques for determination of impact forces during walking and running in a zero-G environment

NASA Technical Reports Server (NTRS)

Greenisen, Michael; Walton, Marlei; Bishop, Phillip; Squires, William

1992-01-01

One of the deleterious adaptations to the microgravity conditions of space flight is the loss of bone mineral content. This loss appears to be at least partially attributable to the minimal skeletal axial loading concomitant with microgravity. The purpose of this study was to develop and fabricate the instruments and hardware necessary to quantify the vertical impact forces (Fz) imparted to users of the space shuttle passive treadmill during human locomotion in a three-dimensional zero-gravity environment. The shuttle treadmill was instrumented using a Kistler forceplate to measure vertical impact forces. To verify that the instruments and hardware were functional, they were tested both in the one-G environment and aboard the KC-135 reduced gravity aircraft. The magnitude of the impact loads generated in one-G on the shuttle treadmill for walking at 0.9 m/sec and running at 1.6 and 2.2 m/sec were 1.1, 1.7, and 1.7 G, respectively, compared with loads of 0.95, 1.2, and 1.5 G in the zero-G environment.

The effects of dynamic loading on the intervertebral disc.

PubMed

Chan, Samantha C W; Ferguson, Stephen J; Gantenbein-Ritter, Benjamin

2011-11-01

Loading is important to maintain the balance of matrix turnover in the intervertebral disc (IVD). Daily cyclic diurnal assists in the transport of large soluble factors across the IVD and its surrounding circulation and applies direct and indirect stimulus to disc cells. Acute mechanical injury and accumulated overloading, however, could induce disc degeneration. Recently, there is more information available on how cyclic loading, especially axial compression and hydrostatic pressure, affects IVD cell biology. This review summarises recent studies on the response of the IVD and stem cells to applied cyclic compression and hydrostatic pressure. These studies investigate the possible role of loading in the initiation and progression of disc degeneration as well as quantifying a physiological loading condition for the study of disc degeneration biological therapy. Subsequently, a possible physiological/beneficial loading range is proposed. This physiological/beneficial loading could provide insight into how to design loading regimes in specific system for the testing of various biological therapies such as cell therapy, chemical therapy or tissue engineering constructs to achieve a better final outcome. In addition, the parameter space of 'physiological' loading may also be an important factor for the differentiation of stem cells towards most ideally 'discogenic' cells for tissue engineering purpose.

Border Collision of Three-Phase Voltage-Source Inverter System with Interacting Loads

NASA Astrophysics Data System (ADS)

Li, Zhen; Liu, Bin; Li, Yining; Wong, Siu-Chung; Liu, Xiangdong; Huang, Yuehui

As a commercial interface, three-phase voltage-source inverters (VSI) are commonly equipped for energy conversion to export DC power from most distributed generation (DG) to the AC utility. Not only do voltage-source converters take charge of converting the power to the loads but support the grid voltage at the point of common connection (PCC) as well, which is dependent on the condition of the grid-connected loads. This paper explores the border collision and its interacting mechanism among the VSI, resistive interacting loads and grids, which manifests as the alternating emergence of the inverting and rectifying operations, where the normal operation is terminated and a new one is assumed. Their mutual effect on the power quality under investigation will cause the circuital stability issue and further deteriorate the voltage regulation capability of VSI by dramatically raising the grid voltage harmonics. It is found in a design-oriented view that the border collision operation will be induced within the unsuitable parameter space with respect to transmission lines of AC grid, resistive loads and internal resistance of VSI. The physical phenomenon is also identified by the theoretical analysis. With numerical simulations for various circuit conditions, the corresponding bifurcation boundaries are collected, where the stability of the system is lost via border collision.

14 CFR 27.341 - Gust loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Gust loads. 27.341 Section 27.341 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.341 Gust loads. The rotorcraft...

14 CFR 27.341 - Gust loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Gust loads. 27.341 Section 27.341 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.341 Gust loads. The rotorcraft...

14 CFR 27.1589 - Loading information.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Loading information. 27.1589 Section 27.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Manual and Approved Manual Material § 27.1589 Loading information. There must be loading instructions for...

14 CFR 27.1589 - Loading information.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Loading information. 27.1589 Section 27.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Manual and Approved Manual Material § 27.1589 Loading information. There must be loading instructions for...

14 CFR 27.1589 - Loading information.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Loading information. 27.1589 Section 27.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Manual and Approved Manual Material § 27.1589 Loading information. There must be loading instructions for...

14 CFR 27.1589 - Loading information.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Loading information. 27.1589 Section 27.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Manual and Approved Manual Material § 27.1589 Loading information. There must be loading instructions for...

14 CFR 27.1589 - Loading information.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Loading information. 27.1589 Section 27.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Manual and Approved Manual Material § 27.1589 Loading information. There must be loading instructions for...

Contact and crack problems for an elastic wedge. [stress concentration in elastic half spaces

NASA Technical Reports Server (NTRS)

Erdogan, F.; Gupta, G. D.

1974-01-01

The contact and the crack problems for an elastic wedge of arbitrary angle are considered. The problem is reduced to a singular integral equation which, in the general case, may have a generalized Cauchy kernel. The singularities under the stamp as well as at the wedge apex were studied, and the relevant stress intensity factors are defined. The problem was solved for various wedge geometries and loading conditions. The results may be applicable to certain foundation problems and to crack problems in symmetrically loaded wedges in which cracks initiate from the apex.

14 CFR 25.1531 - Maneuvering flight load factors.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Maneuvering flight load factors. 25.1531 Section 25.1531 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Operating Limitations § 25.1531 Maneuvering flight load factors. Load factor limitations, not exceeding the...

14 CFR 25.1531 - Maneuvering flight load factors.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Maneuvering flight load factors. 25.1531 Section 25.1531 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Operating Limitations § 25.1531 Maneuvering flight load factors. Load factor limitations, not exceeding the...

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-103

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.

2000-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-103. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the ice/debris/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-103 and the resulting effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-91

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.

1998-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-91. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the ice/debris/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-91 and the resulting effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-93

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.

1999-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-93. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the ice/debris/thermal protection system conditions and integrated photographic analysis findings of Space Shuttle mission STS-93 and the resulting effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-95

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.

1999-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-95. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the ice/debris/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-95 and the resulting effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-90

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.

1998-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-90. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the ice/debris/thermal protection system-conditions and integrated photographic analysis of Space Shuttle mission STS-90 and the resulting effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-80

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.; Lin, Jill D.

1997-01-01

A debris/ice/thermal protection system (TPS) assessment and integrated photographic analysis was conducted for Shuttle mission STS-80. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the ice/debris/thermal protection system conditions and integrated photographic analysis of Shuttle mission Space Transportation System (STS-80) and the resulting effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-89

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.

1998-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-89. Debris inspections of the flight element and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the ice/debris/thermal protection systems conditions and integrated photographic analysis of Space Shuttle mission STS-89 and the resulting effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-112

NASA Technical Reports Server (NTRS)

Oliu, Armando

2002-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-112. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. The report documents the debris/ice/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-112 and the resulting effect of the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-87

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.

1998-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-87. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the-use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the ice/debris/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-87 and the resulting effect on the Space Shuttle Program.

Debris/ice/tps Assessment and Integrated Photographic Analysis of Shuttle Mission STS-96

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.

1999-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-96. Debris inspections of the flight elements and launch pad were performed before and after launch. icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the ice/debris/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-96 and the resulting effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-101

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.

2000-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle Mission STS-101. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in flight anomalies. This report documents the ice/debris/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-101 and the resulting effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-88

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.

1999-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-88. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the ice/debris/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-88 and the resulting effect on the Space Shuttle Program.

Crawl space assisted heat pump. [using stored ground heat

NASA Technical Reports Server (NTRS)

Ternes, M. P.

1980-01-01

A variety of experiments and simulations, currently being designed or underway, to determine the feasibility of conditioning the source air of an air to air heat pump using stored ground heat or cool to produce higher seasonal COP's and net energy savings are discussed. The ground would condition ambient air as it is drawn through the crawl space of a house. Tests designed to evaluate the feasibility of the concept, to determine the amount of heat or cool available from the ground, to study the effect of the system on the heating and cooling loads of the house, to study possible mechanisms which could enhance heat flow through the ground, and to determine if diurnal temperature swings are necessary to achieve successful system performance are described.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-111

NASA Technical Reports Server (NTRS)

Oliu, Armando

2005-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-111. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. The report documents the debris/ice/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-111 and the resulting effect of the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-99

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.

2000-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-99. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the debris/ice/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-99 and the resulting effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-98

NASA Technical Reports Server (NTRS)

Speece, Robert F.

2004-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle Mission STS-98. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the debris/ice/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-98 and the resulting effect on the Space Shuttle Program.

Assessment of crack growth in a space shuttle main engine first-stage, high-pressure fuel turbopump blade

NASA Technical Reports Server (NTRS)

Abdul-Aziz, Ali

1993-01-01

A two-dimensional finite element fracture mechanics analysis of a space shuttle main engine (SSME) turbine blade firtree was performed using the MARC finite element code. The analysis was conducted under combined effects of thermal and mechanical loads at steady-state conditions. Data from a typical engine stand cycle of the SSME were used to run a heat transfer analysis and, subsequently, a thermal structural fracture mechanics analysis. Temperature and stress contours for the firtree under these operating conditions were generated. High stresses were found at the firtree lobes where crack initiation was triggered. A life assessment of the firtree was done by assuming an initial and a final crack size.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-97

NASA Technical Reports Server (NTRS)

Rivera, Jorge E.; Kelly, J. David (Technical Monitor)

2001-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-97. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch were analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the debris /ice/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-97 and the resulting effect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-86

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.; Lin, Jill D.

1997-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-86. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the ice/debris/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-86 and the resulting affect on the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-100

NASA Technical Reports Server (NTRS)

Oliu, Armando

2004-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-100. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. The report documents the debris/ice/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-100 and the resulting effect of the Space Shuttle Program.

Debris/Ice/TPS Assessment and Integrated Photographic Analysis of Shuttle Mission STS-92

NASA Technical Reports Server (NTRS)

Katnik, Gregory N.

2000-01-01

A debris/ice/thermal protection system assessment and integrated photographic analysis was conducted for Shuttle mission STS-92. Debris inspections of the flight elements and launch pad were performed before and after launch. Icing conditions on the External Tank were assessed by the use of computer programs and infrared scanned data during cryogenic loading of the vehicle, followed by on-pad visual inspection. High speed photography of the launch was analyzed to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the debris/ice/thermal protection system conditions and integrated photographic analysis of Space Shuttle mission STS-92 and the resulting effect, if any, on the Space Shuttle Program.

Cryogenic Moisture Analysis of Spray-On Foam Insulation (SOFI)

NASA Technical Reports Server (NTRS)

2008-01-01

The NASA Cryogenics Test Laboratory at Kennedy Space Center conducted long-term testing of SOFI materials under actual-use cryogenic conditions. The lab tested NCFI 24-124 (acreage foam), BX-265 (close-out foam, including intertank flange and bipod areas), and a potential alternate material, NCFI 27-68 (acreage foam with the flame retardant removed). Specimens of all three materials were placed at a site that simulated aging (the Vehicle Assembly Building [VAB]) and a site that simulated weathering (Atmospheric Exposure Test Site [beach site]). After aging/ weathering intervals of 3, 6, and 12 months, the samples were retrieved and tested for their ability to absorb moisture under conditions similar to those experienced by the Space Shuttle External Tank (ET) during the loading of cryogenic propellants.

Furnishing spaceship environment: evaluation of bacterial biofilms on different materials used inside International Space Station.

PubMed

Perrin, Elena; Bacci, Giovanni; Garrelly, Laurent; Canganella, Francesco; Bianconi, Giovanna; Fani, Renato; Mengoni, Alessio

2018-05-08

Performed inside International Space Station (ISS) from 2011 to 2016, VIABLE (eValuatIon And monitoring of microBiofiLms insidE International Space Station) ISS was a long-lasting experiment aimed at evaluating the bacterial contamination on different surface space materials subjected to different pre-treatment, to provide useful information for future space missions. In this work, surfaces samples of the VIABLE ISS experiment were analyzed to determine both the total bacterial load (ATP-metry, qPCR) and the composition of the microbial communities (16S rRNA genes amplicon sequencing). Data obtained showed a low bacterial contamination of all the surfaces, with values in agreement with those allowed inside ISS, and with a taxonomic composition similar to those found in previous studies (Enterobacteriales, Bacillales, Lactobacillales and Actinomycetales). No pre-treatment or material effect were observed on both the bacterial load and the composition of the communities, but for both a slight effect of the position (expose/not expose to air) was observed. In conclusion, under the conditions used for VIABLE ISS, no material or pre-treatment seems to be better than others in terms of quantity and type of bacterial contamination. Copyright © 2018 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

High-Frequency, High-Temperature Fretting Experiments

NASA Technical Reports Server (NTRS)

Matlik, J. F.; Farris, T. N.; Haake, F. K.; Swanson, G. R.; Duke, G. C.

2005-01-01

Fretting is a structural damage mechanism observed when two nominally clamped surfaces are subjected to an oscillatory loading. A critical location for fretting induced damage has been identified at the blade/disk and blade/damper interfaces of gas turbine engine turbomachinery and space propulsion components. The high-temperature, high-frequency loading environment seen by these components lead to severe stress gradients at the edge-of-contact. These contact stresses drive crack nucleation and propagation in fretting and are very sensitive to the geometry of the contacting bodies, the contact loads, materials, temperature, and contact surface tribology (friction). To diagnose the threat that small and relatively undetectable fretting cracks pose to damage tolerance and structural integrity of in-service components, the objective of this work is to develop a well-characterized experimental fretting rig capable of investigating fretting behavior of advanced aerospace alloys subjected to load and temperature conditions representative of such turbomachinery components.

A nonlinear control scheme based on dynamic evolution path theory for improved dynamic performance of boost PFC converter working on nonlinear features.

PubMed

Mohanty, Pratap Ranjan; Panda, Anup Kumar

2016-11-01

This paper is concerned to performance improvement of boost PFC converter under large random load fluctuation, ensuring unity power factor (UPF) at source end and regulated voltage at load side. To obtain such performance, a nonlinear controller based on dynamic evolution path theory is designed and its robustness is examined under both heavy and light loading condition. In this paper, %THD and zero-cross-over dead-zone of input current is significantly reduced. Also, very less response time of input current and output voltage to that of load and reference variation is remarked. A simulation model of proposed system is designed and it is realized using dSPACE 1104 signal processor for a 390V DC , 500W prototype. The relevant experimental and simulation waveforms are presented. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Characterizing the importance of free space in the numerical human body models.

PubMed

Chebil, Omar; Arnoux, Pierre-Jean; Behr, Michel

2015-03-01

The geometric fidelity of the inner organs on finite-element model (FEM) of the human body and the choice to use discontinuous mesh engender the appearance of empty spaces that do not reflect the real-life situation of human body cavities. The aim of this study is to assess the influence of these empty spaces on the behavior of a simplified FEM built with three different structures in interaction which properties are relevant with the abdominal cavity. This FEM is made up of a large sphere (peritoneum) containing two hemispheres (liver and spleen). The space between peritoneum and inner organs was defined with two different approaches and assessed under impact conditions. The first is a meshfree space (Mfs) approach, e.g., consider the space as a perfect gas. The second approach, meshed space (MS), entailed adding volumetric elements in the empty space. From each approach, one optimal configuration was identified regarding the recorded force versus compression, the mobility of inner organs, and the space incompressibility. This space has a considerable influence on the behavior of the FEM and mainly on the applied loadings of inner organs (difference reaching 70% according to the configuration). For the first approach, the incompressible gas is designated because it guarantees space incompressibility (vf/vi = 1) and inner organs loading with the lowest delay (for high impact velocity: Peak force = 89 N, compression 47%). For the second approach, the discontinuous volumetric mesh is preferred because it promotes space incompressibility (vf/vi = 0.94) and acceptable force reaction (for high impact velocity: Peak force = 97 N, compression 49%). The current study shows the importance of this space on the human FEMs cavities behavior and proposes two configurations able to be used in a future study including detailed FEM.

Load-Following Power Timeline Analyses for the International Space Station

NASA Technical Reports Server (NTRS)

Fincannon, James; Delleur, Ann; Green, Robert; Hojnicki, Jeffrey

1996-01-01

Spacecraft are typically complex assemblies of interconnected systems and components that have highly time-varying thermal communications, and power requirements. It is essential that systems designers be able to assess the capability of the spacecraft to meet these requirements which should represent a realistic projection of demand for these resources once the vehicle is on-orbit. To accomplish the assessment from the power standpoint, a computer code called ECAPS has been developed at NASA Lewis Research Center that performs a load-driven analysis of a spacecraft power system given time-varying distributed loading and other mission data. This program is uniquely capable of synthesizing all of the changing spacecraft conditions into a single, seamless analysis for a complete mission. This paper presents example power load timelines with which numerous data are integrated to provide a realistic assessment of the load-following capabilities of the power system. Results of analyses show how well the power system can meet the time-varying power resource demand.

Modal Survey of ETM-3, A 5-Segment Derivative of the Space Shuttle Solid Rocket Booster

NASA Technical Reports Server (NTRS)

Nielsen, D.; Townsend, J.; Kappus, K.; Driskill, T.; Torres, I.; Parks, R.

2005-01-01

The complex interactions between internal motor generated pressure oscillations and motor structural vibration modes associated with the static test configuration of a Reusable Solid Rocket Motor have potential to generate significant dynamic thrust loads in the 5-segment configuration (Engineering Test Motor 3). Finite element model load predictions for worst-case conditions were generated based on extrapolation of a previously correlated 4-segment motor model. A modal survey was performed on the largest rocket motor to date, Engineering Test Motor #3 (ETM-3), to provide data for finite element model correlation and validation of model generated design loads. The modal survey preparation included pretest analyses to determine an efficient analysis set selection using the Effective Independence Method and test simulations to assure critical test stand component loads did not exceed design limits. Historical Reusable Solid Rocket Motor modal testing, ETM-3 test analysis model development and pre-test loads analyses, as well as test execution, and a comparison of results to pre-test predictions are discussed.

Cable load sensing device

DOEpatents

Beus, Michael J.; McCoy, William G.

1998-01-01

Apparatus for sensing the magnitude of a load on a cable as the cable is employed to support the load includes a beam structure clamped to the cable so that a length of the cable lies along the beam structure. A spacer associated with the beam structure forces a slight curvature in a portion of the length of cable under a cable "no-load" condition so that the portion of the length of cable is spaced from the beam structure to define a cable curved portion. A strain gauge circuit including strain gauges is secured to the beam structure by welding. As the cable is employed to support a load the load causes the cable curved portion to exert a force normal to the cable through the spacer and on the beam structure to deform the beam structure as the cable curved portion attempts to straighten under the load. As this deformation takes place, the resistance of the strain gauges is set to a value proportional to the magnitude of the normal strain on the beam structure during such deformation. The magnitude of the normal strain is manipulated in a control device to generate a value equal to the magnitude or weight of the load supported by the cable.

Torsional Tribological Behavior and Torsional Friction Model of Polytetrafluoroethylene against 1045 Steel

PubMed Central

Wang, Shibo; Niu, Chengchao

2016-01-01

In this work, the plane-on-plane torsional fretting tribological behavior of polytetrafluoroethylene (PTFE) was studied. A model of a rigid, flat-ended punch acting on an elastic half-space was built according to the experimental conditions. The results indicate that the shape of T–θ curves was influenced by both the torsional angle and the normal load. The torsion friction torque and wear rate of PTFE exponentially decreased when the torsion angle rose. The torsional torque increased from 0.025 N·m under a normal load of 43 N to 0.082 N·m under a normal load of 123 N. With sequentially increasing normal load, the value of torque was maintained. With rising normal load, the wear mass loss of PTFE disks was increased and the wear rate was decreased. Good agreement was found with the calculated torque according to the model and the experimental torque except for that under a normal load of 163 N. The difference under a normal load of 163 N was caused by the coefficient of friction. Usually the coefficient of friction of a polymer decreases with increasing normal load, whereas a constant coefficient of friction was applied in the model. PMID:26799324

14 CFR 23.726 - Ground load dynamic tests.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ground load dynamic tests. 23.726 Section 23.726 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Landing Gear § 23.726 Ground load dynamic tests. (a) If compliance with the ground load requirements of...

14 CFR 23.726 - Ground load dynamic tests.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ground load dynamic tests. 23.726 Section 23.726 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Landing Gear § 23.726 Ground load dynamic tests. (a) If compliance with the ground load requirements of...

Model-based framework for multi-axial real-time hybrid simulation testing

NASA Astrophysics Data System (ADS)

Fermandois, Gaston A.; Spencer, Billie F.

2017-10-01

Real-time hybrid simulation is an efficient and cost-effective dynamic testing technique for performance evaluation of structural systems subjected to earthquake loading with rate-dependent behavior. A loading assembly with multiple actuators is required to impose realistic boundary conditions on physical specimens. However, such a testing system is expected to exhibit significant dynamic coupling of the actuators and suffer from time lags that are associated with the dynamics of the servo-hydraulic system, as well as control-structure interaction (CSI). One approach to reducing experimental errors considers a multi-input, multi-output (MIMO) controller design, yielding accurate reference tracking and noise rejection. In this paper, a framework for multi-axial real-time hybrid simulation (maRTHS) testing is presented. The methodology employs a real-time feedback-feedforward controller for multiple actuators commanded in Cartesian coordinates. Kinematic transformations between actuator space and Cartesian space are derived for all six-degrees-offreedom of the moving platform. Then, a frequency domain identification technique is used to develop an accurate MIMO transfer function of the system. Further, a Cartesian-domain model-based feedforward-feedback controller is implemented for time lag compensation and to increase the robustness of the reference tracking for given model uncertainty. The framework is implemented using the 1/5th-scale Load and Boundary Condition Box (LBCB) located at the University of Illinois at Urbana- Champaign. To demonstrate the efficacy of the proposed methodology, a single-story frame subjected to earthquake loading is tested. One of the columns in the frame is represented physically in the laboratory as a cantilevered steel column. For realtime execution, the numerical substructure, kinematic transformations, and controllers are implemented on a digital signal processor. Results show excellent performance of the maRTHS framework when six-degrees-of-freedom are controlled at the interface between substructures.

Air-to-Water Heat Pumps With Radiant Delivery in Low-Load Homes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Backman, C.; German, A.; Dakin, B.

2013-12-01

Space conditioning represents nearly 50% of average residential household energy consumption, highlighting the need to identify alternative cost-effective, energy-efficient cooling and heating strategies. As homes are better built, there is an increasing need for strategies that are particularly well suited for high performance, low load homes. ARBI researchers worked with two test homes in hot-dry climates to evaluate the in-situ performance of air-to-water heat pump (AWHP) systems, an energy efficient space conditioning solution designed to cost-effectively provide comfort in homes with efficient, safe, and durable operation. Two monitoring projects of test houses in hot-dry climates were initiated in 2010 tomore » test this system. Both systems were fully instrumented and have been monitored over one year to capture complete performance data over the cooling and heating seasons. Results are used to quantify energy savings, cost-effectiveness, and system performance using different operating modes and strategies. A calibrated TRNSYS model was developed and used to evaluate performance in various climate regions. This strategy is most effective in tight, insulated homes with high levels of thermal mass (i.e. exposed slab floors).« less

Lunar Portable Life Support System Heat Rejection Study

NASA Technical Reports Server (NTRS)

Conger, Bruce; Sompayrac,Robert G.; Trevino, Luis A.; Bue, Grant C.

2009-01-01

Performing extravehicular activity (EVA) at various locations of the lunar surface presents thermal challenges that exceed those experienced in space flight to date. The lunar Portable Life Support System (PLSS) cooling unit must maintain thermal conditions within the space suit and reject heat loads generated by the crewmember and the PLSS equipment. The amount of cooling required varies based on the lunar location and terrain due to the heat transferred between the suit and its surroundings. A study has been completed which investigated the resources required to provide cooling under various lunar conditions, assuming three different thermal technology categories: 1. Spacesuit Water Membrane Evaporator (SWME) 2. Subcooled Phase Change Material (SPCM) 3. Radiators with and without heat pumps Results from the study are presented that show mass and power impacts on the cooling system as a function of the location and terrain on the lunar surface. Resources (cooling equipment mass and consumables) are greater at the equator and inside sunlit craters due to the additional heat loads on the cooling system. While radiator and SPCM technologies require minimal consumables, they come with carry-weight penalties and have limitations. A wider investigation is recommended to determine if these penalties and limitations are offset by the savings in consumables.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roberts, D.; Winkler, J.

As energy-efficiency efforts focus increasingly on existing homes, we scratch our heads about construction decisions made 30, 40, 50-years ago and ask: 'What were they thinking?' A logical follow-on question is: 'What will folks think in 2050 about the homes we're building today?' This question can lead to a lively discussion, but the current practice that we find most alarming is placing ducts in the attic. In this paper, we explore through literature and analysis the impact duct location has on cooling load, peak demand, and energy cost in hot climates. For a typical new home in these climates, wemore » estimate that locating ducts in attics rather than inside conditioned space increases the cooling load 0.5 to 1 ton, increases cooling costs 15% and increases demand by 0.75 kW. The aggregate demand to service duct loss in homes built in Houston, Las Vegas, and Phoenix during the period 2000 through 2009 is estimated to be 700 MW. We present options for building homes with ducts in conditioned space and demonstrate that these options compare favorably with other common approaches to achieving electricity peak demand and consumption savings in homes.« less

Dynamic analysis of Free-Piston Stirling Engine/Linear Alternator-load system-experimentally validated

NASA Technical Reports Server (NTRS)

Kankam, M. David; Rauch, Jeffrey S.; Santiago, Walter

1992-01-01

This paper discusses the effects of variations in system parameters on the dynamic behavior of the Free-Piston Stirling Engine/Linear Alternator (FPSE/LA)-load system. The mathematical formulations incorporate both the mechanical and thermodynamic properties of the FPSE, as well as the electrical equations of the connected load. A state-space technique in the frequency domain is applied to the resulting system of equations to facilitate the evaluation of parametric impacts on the system dynamic stability. Also included is a discussion on the system transient stability as affected by sudden changes in some key operating conditions. Some representative results are correlated with experimental data to verify the model and analytic formulation accuracies. Guidelines are given for ranges of the system parameters which will ensure an overall stable operation.

Dynamic analysis of free-piston Stirling engine/linear alternator-load system - Experimentally validated

NASA Technical Reports Server (NTRS)

Kankam, M. D.; Rauch, Jeffrey S.; Santiago, Walter

1992-01-01

This paper discusses the effects of a variations in system parameters on the dynamic behavior of a Free-Piston Stirling Engine/Linear Alternator (FPSE/LA)-load system. The mathematical formulations incorporates both the mechanical and thermodynamic properties of the FPSE, as well as the electrical equations of the connected load. State-space technique in the frequency domain is applied to the resulting system of equations to facilitate the evaluation of parametric impacts on the system dynamic stability. Also included is a discussion on the system transient stability as affected by sudden changes in some key operating conditions. Some representative results are correlated with experimental data to verify the model and analytic formulation accuracies. Guidelines are given for ranges of the system parameters which will ensure an overall stable operation.

Determination of the effects of wind-induced vibration on cylindrical beams

NASA Technical Reports Server (NTRS)

Artusa, E. A.

1991-01-01

The objective of the analysis was to determine the critical length to diameter ratio (L/Do) of a hollow, cylindrical beam subjected to wind-induced vibration. The sizes of beams ranged from 4 to 24 inches and were composed of ASTM grade A and grade B and American Petroleum Institute grade X42 steels. Calculations used maximum steady-state wind speeds of 130 mph associated with hurricane conditions possible at the Kennedy Space Center. The study examined the effect that different end support and load conditions have on the natural frequencies of the beams. Finally, methods of changing the frequency of the wind-induced vibration were examined. The conclusions drawn were that the greatest possible L/Do is achieved using welded supports and limiting the maximum applied axial and bending loads to less than 50 percent.

Heat transfer optimization for air-mist cooling between a stack of parallel plates

NASA Astrophysics Data System (ADS)

Issa, Roy J.

2010-06-01

A theoretical model is developed to predict the upper limit heat transfer between a stack of parallel plates subject to multiphase cooling by air-mist flow. The model predicts the optimal separation distance between the plates based on the development of the boundary layers for small and large separation distances, and for dilute mist conditions. Simulation results show the optimal separation distance to be strongly dependent on the liquid-to-air mass flow rate loading ratio, and reach a limit for a critical loading. For these dilute spray conditions, complete evaporation of the droplets takes place. Simulation results also show the optimal separation distance decreases with the increase in the mist flow rate. The proposed theoretical model shall lead to a better understanding of the design of fins spacing in heat exchangers where multiphase spray cooling is used.

The Exact Solution for Linear Thermoelastic Axisymmetric Deformations of Generally Laminated Circular Cylindrical Shells

NASA Technical Reports Server (NTRS)

Nemeth, Michael P.; Schultz, Marc R.

2012-01-01

A detailed exact solution is presented for laminated-composite circular cylinders with general wall construction and that undergo axisymmetric deformations. The overall solution is formulated in a general, systematic way and is based on the solution of a single fourth-order, nonhomogeneous ordinary differential equation with constant coefficients in which the radial displacement is the dependent variable. Moreover, the effects of general anisotropy are included and positive-definiteness of the strain energy is used to define uniquely the form of the basis functions spanning the solution space of the ordinary differential equation. Loading conditions are considered that include axisymmetric edge loads, surface tractions, and temperature fields. Likewise, all possible axisymmetric boundary conditions are considered. Results are presented for five examples that demonstrate a wide range of behavior for specially orthotropic and fully anisotropic cylinders.

Time Accurate Unsteady Pressure Loads Simulated for the Space Launch System at a Wind Tunnel Condition

NASA Technical Reports Server (NTRS)

Alter, Stephen J.; Brauckmann, Gregory J.; Kleb, Bil; Streett, Craig L; Glass, Christopher E.; Schuster, David M.

2015-01-01

Using the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics code, an unsteady, time-accurate flow field about a Space Launch System configuration was simulated at a transonic wind tunnel condition (Mach = 0.9). Delayed detached eddy simulation combined with Reynolds Averaged Naiver-Stokes and a Spallart-Almaras turbulence model were employed for the simulation. Second order accurate time evolution scheme was used to simulate the flow field, with a minimum of 0.2 seconds of simulated time to as much as 1.4 seconds. Data was collected at 480 pressure taps at locations, 139 of which matched a 3% wind tunnel model, tested in the Transonic Dynamic Tunnel (TDT) facility at NASA Langley Research Center. Comparisons between computation and experiment showed agreement within 5% in terms of location for peak RMS levels, and 20% for frequency and magnitude of power spectral densities. Grid resolution and time step sensitivity studies were performed to identify methods for improved accuracy comparisons to wind tunnel data. With limited computational resources, accurate trends for reduced vibratory loads on the vehicle were observed. Exploratory methods such as determining minimized computed errors based on CFL number and sub-iterations, as well as evaluating frequency content of the unsteady pressures and evaluation of oscillatory shock structures were used in this study to enhance computational efficiency and solution accuracy. These techniques enabled development of a set of best practices, for the evaluation of future flight vehicle designs in terms of vibratory loads.

Estimation of the Unsteady Aerodynamic Load on Space Shuttle External Tank Protuberances from a Component Wind Tunnel Test

NASA Technical Reports Server (NTRS)

Panda, Jayatana; Martin, Fred W.; Sutliff, Daniel L.

2008-01-01

At the wake of the Columbia (STS-107) accident it was decided to remove the Protuberance Aerodynamic Load (PAL) Ramp that was originally intended to protect various protuberances outside of the Space Shuttle External Tank from high buffet load induced by cross-flows at transonic speed. In order to establish the buffet load without the PAL ramp, a wind tunnel test was conducted where segments of the protuberances were instrumented with dynamic pressure transducers; and power-spectra of sectional lift and drag forces at various span-wise locations between two adjacent support brackets were measured under different cross flow angles, Mach number and other conditions. Additionally, frequency-dependent spatial correlations between the sectional forces were also established. The sectional forces were then adjusted by the correlation length to establish span-averaged spectra of normal and lateral forces that can be suitably "added" to various other unsteady forces encountered by the protuberance. This paper describes the methodology used for calculating the correlation-adjusted power spectrum of the buffet load. A second part of the paper describes wind-tunnel results on the difference in the buffet load on the protuberances with and without the PAL ramp. In general when the ramp height is the same as that of the protuberance height, such as that found on the liquid Oxygen part of the tank, the ramp is found to cause significant reduction of the unsteady aerodynamic load. However, on the liquid Hydrogen part of the tank, where the Oxygen feed-line is far larger in diameter than the height of the PAL ramp, little protection is found to be available to all but the Cable Tray.

Fundamental concepts of structural loading and load relief techniques for the space shuttle

NASA Technical Reports Server (NTRS)

Ryan, R. S.; Mowery, D. K.; Winder, S. W.

1972-01-01

The prediction of flight loads and their potential reduction, using various control system logics for the space shuttle vehicles, is discussed. Some factors not found on previous launch vehicles that increase the complexity are large lifting surfaces, unsymmetrical structure, unsymmetrical aerodynamics, trajectory control system coupling, and large aeroelastic effects. These load-producing factors and load-reducing techniques are analyzed.

Fatigue Behavior and Deformation Mechanisms in Inconel 718 Superalloy Investigated

NASA Technical Reports Server (NTRS)

2005-01-01

The nickel-base superalloy Inconel 718 (IN 718) is used as a structural material for a variety of components in the space shuttle main engine (SSME) and accounts for more than half of the total weight of this engine. IN 718 is the bill-of-material for the pressure vessels of nickel-hydrogen batteries for the space station. In the case of the space shuttle main engine, structural components are typically subjected to startup and shutdown load transients and occasional overloads in addition to high-frequency vibratory loads from routine operation. The nickel-hydrogen battery cells are prooftested before service and are subjected to fluctuating pressure loads during operation. In both of these applications, the structural material is subjected to a monotonic load initially, which is subsequently followed by fatigue. To assess the life of these structural components, it is necessary to determine the influence of a prior monotonic load on the subsequent fatigue life of the superalloy. An insight into the underlying deformation and damage mechanisms is also required to properly account for the interaction between the prior monotonic load and the subsequent fatigue loading. An experimental investigation was conducted to establish the effect of prior monotonic straining on the subsequent fatigue behavior of wrought, double-aged, IN 718 at room temperature. First, monotonic strain tests and fully-reversed, strain-controlled fatigue tests were conducted on uniform-gage-section IN 718 specimens. Next, fully reversed fatigue tests were conducted under strain control on specimens that were monotonically strained in tension. Results from this investigation indicated that prior monotonic straining reduced the fatigue resistance of the superalloy particularly at the lowest strain range. Some of the tested specimens were sectioned and examined by transmission electron microscopy to reveal typical microstructures as well as the active deformation and damage mechanisms under each of the loading conditions. In monotonically strained specimens, deformation during the subsequent fatigue loading was mainly confined to the deformation bands initiated during the prior monotonic straining. This can cause dislocations to move more readily along the previously activated deformation bands and to pile up near grain boundaries, eventually making the grain boundaries susceptible to fatigue crack initiation. The mechanisms inferred from the microstructural investigation were extremely valuable in interpreting the influence of prior monotonic straining on the subsequent fatigue life of Inconel 718 superalloy.

Effects of injection parameters, boost, and swirl ratio on gasoline compression ignition operation at idle and low-load conditions

DOE PAGES

Kodavasal, Janardhan; Kolodziej, Christopher P.; Ciatti, Stephen A.; ...

2016-11-03

In this study, we study the effects of injector nozzle inclusion angle, injection pressure, boost, and swirl ratio on gasoline compression ignition combustion. Closed-cycle computational fluid dynamics simulations using a 1/7th sector mesh representing a single cylinder of a four-cylinder 1.9 L diesel engine, operated in gasoline compression ignition mode with 87 anti-knock index (AKI) gasoline, were performed. Two different operating conditions were studied—the first is representative of idle operation (4 mg fuel/cylinder/cycle, 850 r/min), and the second is representative of a low-load condition (10 mg fuel/cylinder/cycle, 1500 r/min). The mixture preparation and reaction space from the simulations were analyzedmore » to gain insights into the effects of injection pressure, nozzle inclusion angle, boost, and swirl ratio on achieving stable low-load to idle gasoline compression ignition operation. It was found that narrower nozzle inclusion angles allow for more reactivity or propensity to ignition (determined qualitatively by computing constant volume ignition delays) and are suitable over a wider range of injection timings. Under idle conditions, it was found that lower injection pressures helped to reduce overmixing of the fuel, resulting in greater reactivity and ignitability (ease with which ignition can be achieved) of the gasoline. However, under the low-load condition, lower injection pressures did not increase ignitability, and it is hypothesized that this is because of reduced chemical residence time resulting from longer injection durations. Reduced swirl was found to maintain higher in-cylinder temperatures through compression, resulting in better ignitability. It was found that boosting the charge also helped to increase reactivity and advanced ignition timing.« less

Effects of injection parameters, boost, and swirl ratio on gasoline compression ignition operation at idle and low-load conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kodavasal, Janardhan; Kolodziej, Christopher P.; Ciatti, Stephen A.

In this study, we study the effects of injector nozzle inclusion angle, injection pressure, boost, and swirl ratio on gasoline compression ignition combustion. Closed-cycle computational fluid dynamics simulations using a 1/7th sector mesh representing a single cylinder of a four-cylinder 1.9 L diesel engine, operated in gasoline compression ignition mode with 87 anti-knock index (AKI) gasoline, were performed. Two different operating conditions were studied—the first is representative of idle operation (4 mg fuel/cylinder/cycle, 850 r/min), and the second is representative of a low-load condition (10 mg fuel/cylinder/cycle, 1500 r/min). The mixture preparation and reaction space from the simulations were analyzedmore » to gain insights into the effects of injection pressure, nozzle inclusion angle, boost, and swirl ratio on achieving stable low-load to idle gasoline compression ignition operation. It was found that narrower nozzle inclusion angles allow for more reactivity or propensity to ignition (determined qualitatively by computing constant volume ignition delays) and are suitable over a wider range of injection timings. Under idle conditions, it was found that lower injection pressures helped to reduce overmixing of the fuel, resulting in greater reactivity and ignitability (ease with which ignition can be achieved) of the gasoline. However, under the low-load condition, lower injection pressures did not increase ignitability, and it is hypothesized that this is because of reduced chemical residence time resulting from longer injection durations. Reduced swirl was found to maintain higher in-cylinder temperatures through compression, resulting in better ignitability. It was found that boosting the charge also helped to increase reactivity and advanced ignition timing.« less

An Overview of Advanced Elastomeric Seal Development and Testing Capabilities at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Dunlap, Patrick H., Jr.

2014-01-01

NASA is developing advanced space-rated elastomeric seals to support future space exploration missions to low Earth orbit, the Moon, near Earth asteroids, and other destinations. This includes seals for a new docking system and vehicle hatches. These seals must exhibit extremely low leak rates to ensure that astronauts have sufficient breathable air for extended missions. Seal compression loads must be below prescribed limits so as not to overload the mechanisms that compress them, and seal adhesion forces must be low to allow the sealed interface to be separated when required (e.g., during undocking or hatch opening). NASA Glenn Research Center has developed a number of unique test fixtures to measure the leak rates and compression and adhesion loads of candidate seal designs under simulated thermal, vacuum, and engagement conditions. Tests can be performed on fullscale seals with diameters on the order of 50 in., subscale seals that are about 12 in. in diameter, and smaller specimens such as O-rings. Test conditions include temperatures ranging from -238 to 662degF (-150 to 350degC), operational pressure gradients, and seal-on-seal or seal-on-flange mating configurations. Nominal and off-nominal conditions (e.g., incomplete seal compression) can also be simulated. This paper describes the main design features and capabilities of each type of test apparatus and provides an overview of advanced seal development activities at NASA Glenn.

An Overview of Advanced Elastomeric Seal Development and Testing Capabilities at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Dunlap, Patrick H.

2014-01-01

NASA is developing advanced space-rated elastomeric seals to support future space exploration missions to low Earth orbit, the Moon, near Earth asteroids, and other destinations. This includes seals for a new docking system and vehicle hatches. These seals must exhibit extremely low leak rates to ensure that astronauts have sufficient breathable air for extended missions. Seal compression loads must be below prescribed limits so as not to overload the mechanisms that compress them, and seal adhesion forces must be low to allow the sealed interface to be separated when required (e.g., during undocking or hatch opening). NASA Glenn Research Center has developed a number of unique test fixtures to measure the leak rates and compression and adhesion loads of candidate seal designs under simulated thermal, vacuum, and engagement conditions. Tests can be performed on full-scale seals with diameters on the order of 50 in., subscale seals that are about 12 in. in diameter, and smaller specimens such as O-rings. Test conditions include temperatures ranging from -238 to 662 F (-150 to 350 C), operational pressure gradients, and seal-on-seal or seal-on-flange mating configurations. Nominal and off-nominal conditions (e.g., incomplete seal compression) can also be simulated. This paper describes the main design features and capabilities of each type of test apparatus and provides an overview of advanced seal development activities at NASA Glenn.

Jet Flap Stator Blade Test in the High Reaction Turbine Blade Cascade Tunnel

NASA Image and Video Library

1970-03-21

A researcher examines the setup of a jet flap blade in the High Reaction Turbine Blade Cascade Tunnel at the National Aeronautics and Space Administration (NASA) Lewis Research Center. Lewis researchers were seeking ways to increase turbine blade loading on aircraft engines in an effort to reduce the overall size and weight of engines. The ability of each blade to handle higher loads meant that fewer stages and fewer blades were required. This study analyzed the performance of a turbine blade using a jet flap and high loading. A jet of air was injected into the main stream from the pressure surface near the trailing edge. The jet formed an aerodynamic flap which deflected the flow and changed the circulation around the blade and thus increased the blade loading. The air jet also reduced boundary layer thickness. The jet-flap blade design was appealing because the cooling air may also be used for the jet. The performance was studied in a two-dimensional cascade including six blades. The researcher is checking the jet flat cascade with an exit survey probe. The probe measured the differential pressure that was proportional to the flow angle. The blades were tested over a range of velocity ratios and three jet flow conditions. Increased jet flow improved the turning and decreased both the weight flow and the blade loading. However, high blade loadings were obtained at all jet flow conditions.

A Numerical Study on Toppling Failure of a Jointed Rock Slope by Using the Distinct Lattice Spring Model

NASA Astrophysics Data System (ADS)

Lian, Ji-Jian; Li, Qin; Deng, Xi-Fei; Zhao, Gao-Feng; Chen, Zu-Yu

2018-02-01

In this work, toppling failure of a jointed rock slope is studied by using the distinct lattice spring model (DLSM). The gravity increase method (GIM) with a sub-step loading scheme is implemented in the DLSM to mimic the loading conditions of a centrifuge test. A classical centrifuge test for a jointed rock slope, previously simulated by the finite element method and the discrete element model, is simulated by using the GIM-DLSM. Reasonable boundary conditions are obtained through detailed comparisons among existing numerical solutions with experimental records. With calibrated boundary conditions, the influences of the tensional strength of the rock block, cohesion and friction angles of the joints, as well as the spacing and inclination angles of the joints, on the flexural toppling failure of the jointed rock slope are investigated by using the GIM-DLSM, leading to some insight into evaluating the state of flexural toppling failure for a jointed slope and effectively preventing the flexural toppling failure of jointed rock slopes.

Analysis of the 60-Hz power system at KSC: The Orsino substation

NASA Technical Reports Server (NTRS)

Kalu, Alex O.

1989-01-01

An analysis of the Orsino Substation, a component (50 percent) of the 60-Hertz electric power system at the Kennedy Space Center, is presented. Presented here are separate single-line diagrams of the sixteen feeder circuits to permit easy access to information on the individual feeders for future planning. The load condition of each feeder and load break switch are presented and a heuristic reliability analysis of the system is performed. Information is given about the system fashion useful for decision making purposes. The beauty of it is in the simplified manner by which information about the system can be obtained.

The load shedding advisor: An example of a crisis-response expert system

NASA Technical Reports Server (NTRS)

Bollinger, Terry B.; Lightner, Eric; Laverty, John; Ambrose, Edward

1987-01-01

A Prolog-based prototype expert system is described that was implemented by the Network Operations Branch of the NASA Goddard Space Flight Center. The purpose of the prototype was to test whether a small, inexpensive computer system could be used to host a load shedding advisor, a system which would monitor major physical environment parameters in a computer facility, then recommend appropriate operator reponses whenever a serious condition was detected. The resulting prototype performed significantly to efficiency gains achieved by replacing a purely rule-based design methodology with a hybrid approach that combined procedural, entity-relationship, and rule-based methods.

Managing the space-time-load continuum in TMDL planning: A case study for understanding groundwater loads through advanced mapping techniques

EPA Science Inventory

The lag time between groundwater recharge and discharge in a watershed and the potential groundwater load to streams is an important factor in forecasting responses to future land use practices. We call this concept managing the “space-time-load continuum”. It’s understood that i...

Ultra-high speed permanent magnet axial gap alternator with multiple stators

DOEpatents

Hawsey, Robert A.; Bailey, J. Milton

1991-01-01

An ultra-high speed, axial gap alternator that can provide an output to a plurality of loads, the alternator providing magnetic isolation such that operating conditions in one load will not affect operating conditions of another load. This improved alternator uses a rotor member disposed between a pair of stator members, with magnets disposed in each of the rotor member surfaces facing the stator members. The magnets in one surface of the rotor member, which alternate in polarity, are isolated from the magnets in the other surface of the rotor member by a disk of magnetic material disposed between the two sets of magents. In the preferred embodiment, this disk of magnetic material is laminated between two layers of non-magnetic material that support the magnets, and the magnetic material has a peripheral rim that extends to both surfaces of the rotor member to enhance the structural integrity. The stator members are substantially conventional in construction in that equally-spaced and radially-oriented slots are provided, and winding members are laid in these slots. A unit with multiple rotor members and stator members is also described.

Fracture Mechanics Analyses of Reinforced Carbon-Carbon Wing-Leading-Edge Panels

NASA Technical Reports Server (NTRS)

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

2010-01-01

Fracture mechanics analyses of subsurface defects within the joggle regions of the Space Shuttle wing-leading-edge RCC panels are performed. A 2D plane strain idealized joggle finite element model is developed to study the fracture behavior of the panels for three distinct loading conditions - lift-off and ascent, on-orbit, and entry. For lift-off and ascent, an estimated bounding aerodynamic pressure load is used for the analyses, while for on-orbit and entry, thermo-mechanical analyses are performed using the extreme cold and hot temperatures experienced by the panels. In addition, a best estimate for the material stress-free temperature is used in the thermo-mechanical analyses. In the finite element models, the substrate and coating are modeled separately as two distinct materials. Subsurface defects are introduced at the coating-substrate interface and within the substrate. The objective of the fracture mechanics analyses is to evaluate the defect driving forces, which are characterized by the strain energy release rates, and determine if defects can become unstable for each of the loading conditions.

Analysis, testing and verification of the behavior of composite pavements under Florida conditions using a heavy vehicle simulator

NASA Astrophysics Data System (ADS)

Tapia Gutierrez, Patricio Enrique

Whitetopping (WT) is a rehabilitation method to resurface deteriorated asphalt pavements. While some of these composite pavements have performed very well carrying heavy load, other have shown poor performance with early cracking. With the objective of analyzing the applicability of WT pavements under Florida conditions, a total of nine full-scale WT test sections were constructed and tested using a Heavy Vehicle Simulator (HVS) in the APT facility at the FDOT Material Research Park. The test sections were instrumented to monitor both strain and temperature. A 3-D finite element model was developed to analyze the WT test sections. The model was calibrated and verified using measured FWD deflections and HVS load-induced strains from the test sections. The model was then used to evaluate the potential performance of these test sections under critical temperature-load condition in Florida. Six of the WT pavement test sections had a bonded concrete-asphalt interface by milling, cleaning and spraying with water the asphalt surface. This method produced excellent bonding at the interface, with shear strength of 195 to 220 psi. Three of the test sections were intended to have an unbonded concrete-asphalt interface by applying a debonding agent in the asphalt surface. However, shear strengths between 119 and 135 psi and a careful analysis of the strain and the temperature data indicated a partial bond condition. The computer model was able to satisfactorily model the behavior of the composite pavement by mainly considering material properties from standard laboratory tests and calibrating the spring elements used to model the interface. Reasonable matches between the measured and the calculated strains were achieved when a temperature-dependent AC elastic modulus was included in the analytical model. The expected numbers of repetitions of the 24-kip single axle loads at critical thermal condition were computed for the nine test sections based on maximum tensile stresses and fatigue theory. The results showed that 4" slabs can be used for heavy loads only for low-volume traffic. To withstand the critical load without fear of fatigue failure, 6" slabs and 8" slabs would be needed for joint spacings of 4' and 6', respectively.

Minimum distraction gap: how much ankle joint space is enough in ankle distraction arthroplasty?

PubMed

Fragomen, Austin T; McCoy, Thomas H; Meyers, Kathleen N; Rozbruch, S Robert

2014-02-01

The success of ankle distraction arthroplasty relies on the separation of the tibiotalar articular surfaces. The purpose of this study was to find the minimum distraction gap needed to ensure that the tibiotalar joint surfaces would not contact each other with full weight-bearing while under distraction. Circular external fixators were mounted to nine cadaver ankle specimens. Each specimen was then placed into a custom-designed load chamber. Loads of 0, 350, and 700N were applied to the specimen. Radiographic joint space was measured and joint contact pressure was monitored under each load. The external fixator was then sequentially distracted, and the radiographic joint space was measured under the three different loads. The experiment was stopped when there was no joint contact under 700N of load. The radiographic joint space was measured and the initial (undistracted) radiographic joint space was subtracted from it yielding the distraction gap. The minimum distraction gap (mDG) that would provide total unloading was calculated. The average mDG was 2.4 mm (range, 1.6 to 4.0 mm) at 700N of load, 4.4 mm (range, 3.7 to 5.8 mm) at 350N of load, and 4.9 mm (range, 3.7 to 7.0 mm) at 0N of load. These results suggest that if the radiographic joint space of on a standing X-ray of an ankle undergoing distraction arthroplasty shows a minimum of 5.8 mm of DG, then there will be no contact between joint surfaces during full weight-bearing. Therefore, 5 mm of radiographic joint space, as recommended historically, may not be adequate to prevent contact of the articular surfaces during weight-bearing.

Preflight transient dynamic analyses of B-52 aircraft carrying Space Shuttle solid rocket booster drop-test vehicle

NASA Technical Reports Server (NTRS)

Ko, W. L.; Schuster, L. S.

1984-01-01

This paper concerns the transient dynamic analysis of the B-52 aircraft carrying the Space Shuttle solid rocket booster drop test vehicle (SRB/DTV). The NASA structural analysis (NASTRAN) finite element computer program was used in the analysis. The B-52 operating conditions considered for analysis were (1) landing and (2) braking on aborted takeoff runs. The transient loads for the B-52 pylon front and rear hooks were calculated. The results can be used to establish the safe maneuver envelopes for the B-52 carrying the SRB/DTV in landings and brakings.

Pre-flight transient dynamic analysis of B-52 carrying Space Shuttle solid rocket booster drop-test vehicle

NASA Technical Reports Server (NTRS)

Ko, W. L.; Schuster, L. S.

1983-01-01

This paper concerns the transient dynamic analysis of the B-52 aircraft carrying the Space Shuttle solid-rocket booster drop-test vehicle (SRB/DTV). The NASA structural analysis (NASTRAN) finite-element computer program was used in the analysis. The B-52 operating conditions considered for analysis were (1) landing and (2) braking on aborted takeoff runs. The transient loads for the B-52 pylon front and rear hooks were calculated. The results can be used to establish the safe maneuver envelopes for the B-52 carrying the SRB/DTV in landings and brakings.

Evaluation of a metal fuselage frame selectively reinforced with filamentary composites for space shuttle application

NASA Technical Reports Server (NTRS)

Oken, S.; Skoumal, D. E.; Straayer, J. W.

1974-01-01

The development of metal structures reinforced with filamentary composites as a weight saving feature of the space shuttle components is discussed. A frame was selected for study that was representative of the type of construction used in the bulk frames of the orbiter vehicle. Theoretical and experimental investigations were conducted. Component tests were performed to evaluate the critical details used in the designs and to provide credibility to the weight saving results. A model frame was constructed of the reinforced metal material to provide a final evaluation of the construction under realistic load conditions.

Effects of taper and space settings of telescopic Ce-TZP/A crowns on retentive force and settling.

PubMed

Nakagawa, Shusuke; Torii, Katsunori; Tanaka, Masahiro

2017-03-31

The aim of this study was to investigate the effect of the taper and space setting of using Ce-TZP/A on retentive force and secondary crown settling. The taper were 2°, 4°, and 6°, and the space settings were 0 and 10 μm. The applied loads were 50 and 100 N. The taper had a significant effect on retentive force and settling at both loads (p<0.05). The space settings did not have a significant effect on retentive force or settling at either load (p<0.05). The taper of the telescopic crowns and the load affected the retentive force and the settling.

14 CFR 27.301 - Loads.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Loads. 27.301 Section 27.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 25.301 - Loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Loads. 25.301 Section 25.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... equilibrium with inertia forces, considering each item of mass in the airplane. These loads must be...

14 CFR 29.301 - Loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Loads. 29.301 Section 29.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 29.301 - Loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Loads. 29.301 Section 29.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 27.301 - Loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Loads. 27.301 Section 27.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 27.301 - Loads.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Loads. 27.301 Section 27.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 27.301 - Loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Loads. 27.301 Section 27.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 29.301 - Loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Loads. 29.301 Section 29.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 29.301 - Loads.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Loads. 29.301 Section 29.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 29.301 - Loads.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Loads. 29.301 Section 29.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 27.301 - Loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Loads. 27.301 Section 27.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 27.337 - Limit maneuvering load factor.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Limit maneuvering load factor. 27.337 Section 27.337 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.337...

14 CFR 27.427 - Unsymmetrical loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Unsymmetrical loads. 27.427 Section 27.427 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Control Surface and System Loads § 27.427...

14 CFR 31.21 - Loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Loads. 31.21 Section 31.21 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Strength Requirements § 31.21 Loads. Strength requirements are specified in terms of...

14 CFR 31.21 - Loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Loads. 31.21 Section 31.21 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Strength Requirements § 31.21 Loads. Strength requirements are specified in terms of...

14 CFR 23.1589 - Loading information.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Loading information. 23.1589 Section 23.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Information Airplane Flight Manual and Approved Manual Material § 23.1589 Loading information. The following...

14 CFR 23.1589 - Loading information.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Loading information. 23.1589 Section 23.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Information Airplane Flight Manual and Approved Manual Material § 23.1589 Loading information. The following...

14 CFR 23.1589 - Loading information.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Loading information. 23.1589 Section 23.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Information Airplane Flight Manual and Approved Manual Material § 23.1589 Loading information. The following...

14 CFR 23.1589 - Loading information.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Loading information. 23.1589 Section 23.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Information Airplane Flight Manual and Approved Manual Material § 23.1589 Loading information. The following...

14 CFR 23.1589 - Loading information.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Loading information. 23.1589 Section 23.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Information Airplane Flight Manual and Approved Manual Material § 23.1589 Loading information. The following...

Architecture of high-rise buildings as a brand of the modern Kazakhstan

NASA Astrophysics Data System (ADS)

Abdrassilova, Gulnara; Kozbagarova, Nina; Tuyakayeva, Ainagul

2018-03-01

Using practical examples article reviews urban-planning and space-planning features of design and construction of high-rise buildings in Kazakhstan conditions; methods are identified that provide for structural stability against wind and seismic loads based on innovative technical and technological solutions. Article authors stress out the fashion function of high-rise buildings in the new capital of Kazakhstan, the Astana city.

Structural load control during construction

NASA Technical Reports Server (NTRS)

Mikulas, Martin M., Jr.

1991-01-01

In the absence of gravitational pull, the major design considerations for large space structures are stiffness for controllability, and transient dynamic loadings (as opposed to the traditional static load associated with earth-based structures). Because of the absence of gravitational loading, space structures can be designed to be significantly lighter than their counterparts on Earth. For example, the Space Shuttle manipulator arm is capable of moving and positioning a 60,000 lb payload, yet weighs less than 1,000 lbs. A recent design for the Space Station which had a total weight of about 500,000 lbs. used a primary loadcarrying keel beam which weighed less than 10,000 lbs. For many large space structures designs it is quite common for the load-carrying structure to have a mass fraction on the order of one or two percent of the total spacecraft mass. This significant weight reduction for large space structures is commonly accompanied by very low natural frequencies. These low frequencies cause an unprecedented level of operational complexity for mission applications which require a high level of positioning and control accuracy. This control problem is currently the subject of considerable research directed towards reducing the flexibility problem. In addition, however, the small mass fraction typically results in structures which are quite unforgiving to inadvertent high loadings. In other words, the structures are 'fragile.' In order to deal with the fragility issue CSC developed a load-limiting concept for space truss structures. This concept is aimed at limiting the levels of load which can occur in a large space structure during the construction process as well as during subsequent operations. Currently, the approach for dealing with large loadings is to make the structure larger. The impact this has on construction is significant. The larger structures are more difficult to package in the launch vehicle, and in fact in some instances the concept must be changed from a deployable truss to an erectable truss to permit packaging. The new load-limiting concept is aimed at permitting the use in large space structures of smaller trusses with a high level of strength robustness, in order to simplify the construction process. To date several analyses conducted on the concept have demonstrated its feasibility, and an experiment is currently being designed to demonstrate its operation.

Structural Analysis of an Inflation-Deployed Solar Sail With Experimental Validation

NASA Technical Reports Server (NTRS)

Sleight, David W.; Michii, Yuki; Lichodziejewski, David; Derbes, Billy; Mann, Troy O.

2005-01-01

Under the direction of the NASA In-Space Propulsion Technology Office, the team of L Garde, NASA Jet Propulsion Laboratory, Ball Aerospace, and NASA Langley Research Center has been developing a scalable solar sail configuration to address NASA s future space propulsion needs. Prior to a flight experiment of a full-scale solar sail, a comprehensive phased test plan is currently being implemented to advance the technology readiness level of the solar sail design. These tests consist of solar sail component, subsystem, and sub-scale system ground tests that simulate the vacuum and thermal conditions of the space environment. Recently, two solar sail test articles, a 7.4-m beam assembly subsystem test article and a 10-m four-quadrant solar sail system test article, were tested in vacuum conditions with a gravity-offload system to mitigate the effects of gravity. This paper presents the structural analyses simulating the ground tests and the correlation of the analyses with the test results. For programmatic risk reduction, a two-prong analysis approach was undertaken in which two separate teams independently developed computational models of the solar sail test articles using the finite element analysis software packages: NEiNastran and ABAQUS. This paper compares the pre-test and post-test analysis predictions from both software packages with the test data including load-deflection curves from static load tests, and vibration frequencies and mode shapes from structural dynamics tests. The analysis predictions were in reasonable agreement with the test data. Factors that precluded better correlation of the analyses and the tests were uncertainties in the material properties, test conditions, and modeling assumptions used in the analyses.

Finite Element Analysis and Test Correlation of a 10-Meter Inflation-Deployed Solar Sail

NASA Technical Reports Server (NTRS)

Sleight, David W.; Michii, Yuki; Lichodziejewski, David; Derbes, Billy; Mann. Troy O.; Slade, Kara N.; Wang, John T.

2005-01-01

Under the direction of the NASA In-Space Propulsion Technology Office, the team of L Garde, NASA Jet Propulsion Laboratory, Ball Aerospace, and NASA Langley Research Center has been developing a scalable solar sail configuration to address NASA's future space propulsion needs. Prior to a flight experiment of a full-scale solar sail, a comprehensive phased test plan is currently being implemented to advance the technology readiness level of the solar sail design. These tests consist of solar sail component, subsystem, and sub-scale system ground tests that simulate the vacuum and thermal conditions of the space environment. Recently, two solar sail test articles, a 7.4-m beam assembly subsystem test article and a 10-m four-quadrant solar sail system test article, were tested in vacuum conditions with a gravity-offload system to mitigate the effects of gravity. This paper presents the structural analyses simulating the ground tests and the correlation of the analyses with the test results. For programmatic risk reduction, a two-prong analysis approach was undertaken in which two separate teams independently developed computational models of the solar sail test articles using the finite element analysis software packages: NEiNastran and ABAQUS. This paper compares the pre-test and post-test analysis predictions from both software packages with the test data including load-deflection curves from static load tests, and vibration frequencies and mode shapes from vibration tests. The analysis predictions were in reasonable agreement with the test data. Factors that precluded better correlation of the analyses and the tests were uncertainties in the material properties, test conditions, and modeling assumptions used in the analyses.

Bicycle ergometer instrumentation to determine muscle and bone forces during exercise

NASA Technical Reports Server (NTRS)

Figueroa, Fernando

1995-01-01

It is hypothesized that bone loss experienced by astronauts in zero gravity conditions may be curtailed by appropriate exercise. According to Wolf's law, bone regenerates when muscles produce stresses by pulling on the bone during daily activity and/or exercise on Earth. to use this theory to prevent or decrease bone loss, one needs to quantify musculoskeletal loads and relate them to bone density changes. In the context of the space program, it is desirable to determine musculoskeletal loads during exercise (using the bicycle ergometer in this case) so that one may make similar measurements on Earth and in space. In this manner, load measurements on Earth may be used as reference to generate similar loads during exercise in space. The work reported in this document entails a musculoskeletal load measurement system that, when complete, will provide forces at muscle insertion points and other contact points, on bone. This data will be used by Dr. Beth A. Todd, who is also a SSF working with Dr. Shackelford, as input to a finite element model of bone sections to determine stress distributions. A bicycle ergometer has been instrumented to measure parameters needed to determine musculoskeletal forces during exercise. A primary feature of the system is its compactness. It uses small/light sensors without line-of-sight requirements. The system developed includes sensors, signal processing, a data acquisition system, and software to collect the data. The sensors used include optical encoders to measure position and orientation of the pedal (foot), accelerometers to determine kinematic parameters of the shank and thigh, load cells to measure pedal forces on the sagittal plane, and EMG probes to measure muscle activity. The signals are processed using anti-aliasing filters and amplifiers. The sensors' output is digitized using 30 channels of a board mounted inside a 486 class PC. A program sets the data acquisition parameters and collects data during a time period specified by the user. The data is put directly into a file on the hard disk in binary form. The 30 channels are sampled at 200 KHz, and each 30 channel scan is done at a rate of 1000 Hz. The instrumented ergometer has been flown in the KC-135 zero-gravity (zero-g) flight to collect information needed to determine musculoskeletal forces under these conditions. Similar information has been collected in 1-g conditions for comparision with the results from the zero-g case. At this time, the sets of data from both experiments are being processed. An existing methodology will be used to determine the kinematic parameters of the shank and thigh using accelerometer and encoder data. This methodology was developed during the fellow's previous NASA/ASEE fellowship and thanks to a Director's Grant. In the future, a methodology to determine the musculoskeletal forces using Newton's Law of Motion and optimization techniques will be developed to determine forces exerted by particular muscles.

Comparison of reusable insulation systems for cryogenically-tanked earth-based space vehicles

NASA Technical Reports Server (NTRS)

Sumner, I. E.; Barber, J. R.

1978-01-01

Three reusable insulation systems concepts have been developed for use with cryogenic tanks of earth-based space vehicles. Two concepts utilized double-goldized Kapton (DGK) or double-aluminized Mylar (DAM) multilayer insulation (MLI), while the third utilized a hollow-glass-microsphere, load-bearing insulation (LBI). All three insulation systems have recently undergone experimental testing and evaluation under NASA-sponsored programs. Thermal performance measurements were made under space-hold (vacuum) conditions for insulation warm boundary temperatures of approximately 291 K. The resulting effective thermal conductivity was approximately .00008 W/m-K for the MLI systems (liquid hydrogen test results) and .00054 W/m-K for the LBI system (liquid nitrogen test results corrected to liquid hydrogen temperature). The DGK MLI system experienced a maximum thermal degradation of 38 percent, the DAM MLI system 14 percent, and the LBI system 6.7 percent due to repeated thermal cycling representing typical space flight conditions. Repeated exposure of the DAM MLI system to a high humidity environment for periods as long as 8 weeks provided a maximum degradation of only 24 percent.

Parallel satellite orbital situational problems solver for space missions design and control

NASA Astrophysics Data System (ADS)

Atanassov, Atanas Marinov

2016-11-01

Solving different scientific problems for space applications demands implementation of observations, measurements or realization of active experiments during time intervals in which specific geometric and physical conditions are fulfilled. The solving of situational problems for determination of these time intervals when the satellite instruments work optimally is a very important part of all activities on every stage of preparation and realization of space missions. The elaboration of universal, flexible and robust approach for situation analysis, which is easily portable toward new satellite missions, is significant for reduction of missions' preparation times and costs. Every situation problem could be based on one or more situation conditions. Simultaneously solving different kinds of situation problems based on different number and types of situational conditions, each one of them satisfied on different segments of satellite orbit requires irregular calculations. Three formal approaches are presented. First one is related to situation problems description that allows achieving flexibility in situation problem assembling and presentation in computer memory. The second formal approach is connected with developing of situation problem solver organized as processor that executes specific code for every particular situational condition. The third formal approach is related to solver parallelization utilizing threads and dynamic scheduling based on "pool of threads" abstraction and ensures a good load balance. The developed situation problems solver is intended for incorporation in the frames of multi-physics multi-satellite space mission's design and simulation tools.

KSC-2014-3931

NASA Image and Video Library

2014-09-11

SAN DIEGO, Calif. – The USS Anchorage is docked at Naval Base San Diego during loading operations in its well deck for Orion Underway Recovery Test 3. A crane is used to lift the Orion forward bay cover for loading on the ship. The ship will head out to sea, off the coast of San Diego, in search of conditions to support test needs for a full dress rehearsal of recovery operations. NASA, Lockheed Martin and U.S. Navy personnel will conduct tests in the Pacific Ocean to prepare for recovery of the Orion crew module on its return from a deep space mission. The test will allow the teams to demonstrate and evaluate the recovery processes, procedures, new hardware and personnel in open waters. The Ground Systems Development and Operations Program is conducting the underway recovery tests. Orion is the exploration spacecraft designed to carry astronauts to destinations not yet explored by humans, including an asteroid and Mars. It will have emergency abort capability, sustain the crew during space travel and provide safe re-entry from deep space return velocities. The first unpiloted test flight of Orion is scheduled to launch in 2014 atop a United Launch Alliance Delta IV Heavy rocket and in 2018 on NASA’s Space Launch System rocket. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Cory Huston

A digital computer simulation and study of a direct-energy-transfer power-conditioning system

NASA Technical Reports Server (NTRS)

Burns, W. W., III; Owen, H. A., Jr.; Wilson, T. G.; Rodriguez, G. E.; Paulkovich, J.

1975-01-01

An investigation of the behavior of the power-conditioning system as a whole is a necessity to ensure the integrity of the aggregate system in the case of space applications. An approach for conducting such an investigation is considered. A description is given of the application of a general digital analog simulator program to the study of an aggregate power-conditioning system which is being developed for use on the International Ultraviolet Explorer spacecraft. The function of the direct energy transfer system studied involves a coupling of a solar array through a main distribution bus to the spacecraft electrical loads.

Adaptive Control for Buck Power Converter Using Fixed Point Inducting Control and Zero Average Dynamics Strategies

NASA Astrophysics Data System (ADS)

Hoyos Velasco, Fredy Edimer; García, Nicolás Toro; Garcés Gómez, Yeison Alberto

In this paper, the output voltage of a buck power converter is controlled by means of a quasi-sliding scheme. The Fixed Point Inducting Control (FPIC) technique is used for the control design, based on the Zero Average Dynamics (ZAD) strategy, including load estimation by means of the Least Mean Squares (LMS) method. The control scheme is tested in a Rapid Control Prototyping (RCP) system based on Digital Signal Processing (DSP) for dSPACE platform. The closed loop system shows adequate performance. The experimental and simulation results match. The main contribution of this paper is to introduce the load estimator by means of LMS, to make ZAD and FPIC control feasible in load variation conditions. In addition, comparison results for controlled buck converter with SMC, PID and ZAD-FPIC control techniques are shown.

Light Water Breeder Reactor fuel rod design and performance characteristics (LWBR Development Program)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campbell, W.R.; Giovengo, J.F.

1987-10-01

Light Water Breeder Reactor (LWBR) fuel rods were designed to provide a reliable fuel system utilizing thorium/uranium-233 mixed-oxide fuel while simultaneously minimizing structural material to enhance fuel breeding. The fuel system was designed to be capable of operating successfully under both load follow and base load conditions. The breeding objective required thin-walled, low hafnium content Zircaloy cladding, tightly spaced fuel rods with a minimum number of support grid levels, and movable fuel rod bundles to supplant control rods. Specific fuel rod design considerations and their effects on performance capability are described. Successful completion of power operations to over 160 percentmore » of design lifetime including over 200 daily load follow cycles has proven the performance capability of the fuel system. 68 refs., 19 figs., 44 tabs.« less

Design of a photovoltaic system for a southwest all-electric residence

NASA Astrophysics Data System (ADS)

Mehalick, E. M.; Obrien, G.; Tully, G. F.; Johnson, J.; Parker, J.

1980-04-01

The grid connected residential photovoltaic system for the Southwest is designed to meet both space conditioning requirements and all conventional electrical load requirements for an all-electric residence. The system is comprised of two major subsystems, the solar array and the power conditioning subsystem (PCS). An 8 kW peak photovoltaic array been designed for the house. The 93 square meters solar array uses a shingle solar cell module in a highly redundant series/parallel matrix. The photovoltaic generated power is supplied to a 10kVA power conversion subsystem which is controlled to track the solar array maximum power operating point and feed the 240 Vac output power directly to the house loads or back to the utility when excess power is generated. The photovoltaic power is isolated from the utility by a 15 kVA transformer. The house design and subsystem specifications are given in detail.

Numerical Simulation and Validation of a High Head Model Francis Turbine at Part Load Operating Condition

NASA Astrophysics Data System (ADS)

Goyal, Rahul; Trivedi, Chirag; Kumar Gandhi, Bhupendra; Cervantes, Michel J.

2017-07-01

Hydraulic turbines are operated over an extended operating range to meet the real time electricity demand. Turbines operated at part load have flow parameters not matching the designed ones. This results in unstable flow conditions in the runner and draft tube developing low frequency and high amplitude pressure pulsations. The unsteady pressure pulsations affect the dynamic stability of the turbine and cause additional fatigue. The work presented in this paper discusses the flow field investigation of a high head model Francis turbine at part load: 50% of the rated load. Numerical simulation of the complete turbine has been performed. Unsteady pressure pulsations in the vaneless space, runner, and draft tube are investigated and validated with available experimental data. Detailed analysis of the rotor stator interaction and draft tube flow field are performed and discussed. The analysis shows the presence of a rotating vortex rope in the draft tube at the frequency of 0.3 times of the runner rotational frequency. The frequency of the vortex rope precession, which causes severe fluctuations and vibrations in the draft tube, is predicted within 3.9% of the experimental measured value. The vortex rope results pressure pulsations propagating in the system whose frequency is also perceive in the runner and upstream the runner.

Improvement of structural models using covariance analysis and nonlinear generalized least squares

NASA Technical Reports Server (NTRS)

Glaser, R. J.; Kuo, C. P.; Wada, B. K.

1992-01-01

The next generation of large, flexible space structures will be too light to support their own weight, requiring a system of structural supports for ground testing. The authors have proposed multiple boundary-condition testing (MBCT), using more than one support condition to reduce uncertainties associated with the supports. MBCT would revise the mass and stiffness matrix, analytically qualifying the structure for operation in space. The same procedure is applicable to other common test conditions, such as empty/loaded tanks and subsystem/system level tests. This paper examines three techniques for constructing the covariance matrix required by nonlinear generalized least squares (NGLS) to update structural models based on modal test data. The methods range from a complicated approach used to generate the simulation data (i.e., the correct answer) to a diagonal matrix based on only two constants. The results show that NGLS is very insensitive to assumptions about the covariance matrix, suggesting that a workable NGLS procedure is possible. The examples also indicate that the multiple boundary condition procedure more accurately reduces errors than individual boundary condition tests alone.

Biomechanics of a Bone-Periodontal Ligament-Tooth Fibrous Joint

PubMed Central

Lin, Jeremy D.; Özcoban, Hüseyin; Greene, Janelle; Jang, Andrew T.; Djomehri, Sabra; Fahey, Kevin; Hunter, Luke; Schneider, Gerold A; Ho, Sunita P.

2013-01-01

This study investigates bone-tooth association under compression to identify strain amplified sites within the bone-periodontal ligament (PDL)-tooth fibrous joint. Our results indicate that the biomechanical response of the joint is due to a combinatorial response of constitutive properties of organic, inorganic, and fluid components. Second maxillary molars within intact maxillae (N=8) of 5-month-old rats were loaded with a μ-XCT-compatible in situ loading device at various permutations of displacement rates (0.2, 0.5, 1.0, 1.5, 2.0 mm/min) and peak reactionary load responses (5, 10, 15, 20 N). Results indicated a nonlinear biomechanical response of the joint, in which the observed reactionary load rates were directly proportional to displacement rates (velocities). No significant differences in peak reactionary load rates at a displacement rate of 0.2 mm/min were observed. However, for displacement rates greater than 0.2 mm/min, an increasing trend in reactionary rate was observed for every peak reactionary load with significant increases at 2.0 mm/min. Regardless of displacement rates, two distinct behaviors were identified with stiffness (S) and reactionary load rate (LR) values at a peak load of 5 N (S5 N=290–523 N/mm) being significantly lower than those at 10 N (LR5 N=1–10 N/s) and higher (S10N–20 N=380–684 N/mm; LR10N–20 N=1–19 N/s). Digital image correlation revealed the possibility of a screw-like motion of the tooth into the PDL-space, i.e., predominant vertical displacement of 35 μm at 5 N, followed by a slight increase to 40 μm at 10 N and 50 μm at 20 N of the tooth and potential tooth rotation at loads above 10 N. Narrowed and widened PDL spaces as a result of tooth displacement indicated areas of increased apparent strain within the complex. We propose that such highly strained regions are “hot spots” that can potentiate local tissue adaptation under physiological loading and adverse tissue adaptation under pathological loading conditions. PMID:23219279

Solar project description for Helio-Thermics, Inc., lot 6 single family residence; Greenville, South Carolina

NASA Astrophysics Data System (ADS)

Moore, D.

1981-03-01

An instrumented single family residence in Greenville, South Carolina, has approximately 1086 square feet on conditioned space. Solar energy is used for space heating the home and preheating domestic and water (DHW). Solar energy enters the attic through a 416 square foot aperture which is double glazed with corrugated, translucent, fiberglass reinforced, acrylic panels. Warm air accumulates in the peak of the attic roof and circulates through the conditioned space or through storage by an air handler. Solar energy is stored in an 870 cubic foot storage bin containing 85,460 pounds of crushed rock located under the house. cold water is preheated in the attic by thermosiphoning water from the 80 gallon preheat tank through a manifold system of copper tubes. These tubes are attached to black sheet metal plates. Preheated city water is stored in the preheat tank and supplied, on demand, to a conventional 80 gallon DHW tank. When solar energy is insufficient to satisfy the space heating load, a water to air heat exchanger in the hot air supply duct provides auxiliary energy for space heating. A gas fired water heater provides auxiliary energy for the water to air heat exchanger and the DHW.

Thrust-isolating mounting. [characteristics of support for loads mounted in spacecraft

NASA Technical Reports Server (NTRS)

Wetzler, D. G. (Inventor)

1974-01-01

A supporting frame for a load, such as one or more telescopes, is isolated from all multi-gravitational forces, which will be developed within that load as that load is propelled into space, by using a shroud to fully and solidly hold that load until that load has been propelled into space. Thereafter, that shroud will be jettisoned; and then supports which are on, and which are movable with, that load will have surfaces thereon moved into supporting engagement with complementary surfaces on that supporting frame to enable that supporting frame and those supports to fully and solidly hold that load.

A Compendium of Wind Statistics and Models for the NASA Space Shuttle and Other Aerospace Vehicle Programs

NASA Technical Reports Server (NTRS)

Smith, O. E.; Adelfang, S. I.

1998-01-01

The wind profile with all of its variations with respect to altitude has been, is now, and will continue to be important for aerospace vehicle design and operations. Wind profile databases and models are used for the vehicle ascent flight design for structural wind loading, flight control systems, performance analysis, and launch operations. This report presents the evolution of wind statistics and wind models from the empirical scalar wind profile model established for the Saturn Program through the development of the vector wind profile model used for the Space Shuttle design to the variations of this wind modeling concept for the X-33 program. Because wind is a vector quantity, the vector wind models use the rigorous mathematical probability properties of the multivariate normal probability distribution. When the vehicle ascent steering commands (ascent guidance) are wind biased to the wind profile measured on the day-of-launch, ascent structural wind loads are reduced and launch probability is increased. This wind load alleviation technique is recommended in the initial phase of vehicle development. The vehicle must fly through the largest load allowable versus altitude to achieve its mission. The Gumbel extreme value probability distribution is used to obtain the probability of exceeding (or not exceeding) the load allowable. The time conditional probability function is derived from the Gumbel bivariate extreme value distribution. This time conditional function is used for calculation of wind loads persistence increments using 3.5-hour Jimsphere wind pairs. These increments are used to protect the commit-to-launch decision. Other topics presented include the Shuttle Shuttle load-response to smoothed wind profiles, a new gust model, and advancements in wind profile measuring systems. From the lessons learned and knowledge gained from past vehicle programs, the development of future launch vehicles can be accelerated. However, new vehicle programs by their very nature will require specialized support for new databases and analyses for wind, atmospheric parameters (pressure, temperature, and density versus altitude), and weather. It is for this reason that project managers are encouraged to collaborate with natural environment specialists early in the conceptual design phase. Such action will give the lead time necessary to meet the natural environment design and operational requirements, and thus, reduce development costs.

Liquid Rocket Booster (LRB) for the Space Transportation System (STS) systems study. Appendix E: Pressure-fed booster test bed for the liquid rocket booster study

NASA Technical Reports Server (NTRS)

1989-01-01

The stress analysis/structural design of the Pressure-Fed Booster Engine Test Bed using the existing F-1 Test Facility Test Stand at Huntsville, Alabama is described. The analysis has been coded and set up for solution on NASTRAN. A separate stress program was established to take the NASTRAN output and perform stress checks on the members. Joint checks and other necessary additional checks were performed by hand. The notes include a brief description of other programs which assist in reproducing and reviewing the NASTRAN results. The redesign of the test stand members and the stress analysis was performed per the A.I.S.C. Code. Loads on the stand consist of the loaded run tanks; wind loads; seismic loads; live loads consisting of snow and ice: live and dead loads of steel; and loaded pressurant bottle. In combining loads, wind loads and seismic loads were each combined with full live loads. Wind and seismic loads were not combined. No one third increase in allowables was taken for the environmental loads except at decks 147 and 214, where the increase was used when considering the stay rods, brackets and stay beams. Wind and seismic loads were considered from each of the four coordinate directions (i.e. N,S,E,W) to give eight basic conditions. The analysis was run with the pressurant tank mounted at level 125. One seismic condition was also run with the tank mounted at levels 169 and 214. No failures were noted with mounting at level 169, but extensive deck failure with mounting at level 214 (the loadsets used are included on the tape, but no detailed results are included in the package). Decking support beams at levels 147 and 214 are not included in the model. The stress program thus does not reduce strut lengths to the length between support beams (the struts are attached to the beams at intersection points) and gives stress ratios larger than one for some of the struts. The affected members were therefore checked by hand.

Human tolerance to space flight

NASA Technical Reports Server (NTRS)

Huntoon, C. L.

1989-01-01

Medical studies of astronauts and cosmonauts before, during, and after space missions have identified several effects of weightlessness and other factors that influence the ability of humans to tolerate space flight. Weightlessness effects include space motion sickness, cardiovascular abnormalities, reduction in immune system function, loss of red blood cells, loss of bone mass, and muscle atrophy. Extravehicular activity (EVA) increases the likelihood that decompression sickness may occur. Radiation also gives reason for concern about health of crewmembers, and psychological factors are important on long-term flights. Countermeasures that have been used include sensory preadaptation, prebreathing and use of various air mixtures for EVA, loading with water and electrolytes, exercise, use of pharmacological agents and special diets, and psychological support. It appears that humans can tolerate and recover satisfactorily from at least one year of space flight, but a number of conditions must be further ameliorated before long-duration missions can be considered routine.

Design of an integral thermal protection system for future space vehicles

NASA Astrophysics Data System (ADS)

Bapanapalli, Satish Kumar

Thermal protection systems (TPS) are the features incorporated into a spacecraft's design to protect it from severe aerodynamic heating during high-speed travel through planetary atmospheres. The ablative TPS on the space capsule Apollo and ceramic tiles and blankets on the Space Shuttle Orbiter were designed as add-ons to the main load-bearing structure of the vehicles. They are usually incompatible with the structure due to mismatch in coefficient of thermal expansion and as a result the robustness of the external surface of the spacecraft is compromised. This could potentially lead to catastrophic consequences because the TPS forms the external surface of the vehicle and is subjected to numerous other loads like aerodynamic pressure loads, small object high-speed impacts and handling damages during maintenance. In order to make the spacecraft external surface robust, an Integral Thermal Protection System (ITPS) concept has been proposed in this research in which the load-bearing structure and the TPS are combined into one single structure. The design of an ITPS is a formidable task because the requirement of a load-bearing structure and a TPS are often contradictory to one another. The design process has been formulated as an optimization problem with mass per unit area of the ITPS as the objective function and the various functions of the ITPS were formulated as constraints. This is a multidisciplinary design optimization problem involving heat transfer and structural analysis fields. The constraints were expressed as response surface approximations obtained from a large number of finite element analyses, which were carried out with combinations of design variables obtained from an optimized Latin-Hypercube sampling scheme. A MATLABRTM code has been developed to carry out these FE analyses automatically in conjunction with ABAQUSRTM . Corrugated-core structures were designed for ITPS applications with loads and boundary conditions similar to that of a Space Shuttle-like vehicle. Temperature, buckling, deflection and stress constraints were considered for the design process. An optimized mass ranging between 3.5--5 lb/ft2 was achieved by the design. This is considerably heavier when compared to conventional TPS designs. However, the ITPS can withstand substantially large mechanical loads when compared to the conventional TPS. Truss-core geometries used for ITPS design in this research were found to be unsuitable as they could not withstand large thermal gradients frequently encountered in ITPS applications. The corrugated-core design was used for further studying the influence of the various input parameters on the final design weight of the ITPS. It was observed that boundary conditions not only significantly influence the ITPS design but also have a major impact on the effect of various input parameters. It was found that even a small amount of heat loss from bottom face sheet leads to significant reduction in ITPS weight. Aluminum and Beryllium are the most suitable materials for bottom face sheet with Beryllium having considerable advantages in terms of heat capacity, stiffness and density. Although ceramic matrix composites have many superior properties when compared to metal alloys (Titanium alloys and Inconel), their low tensile strength presents difficulties in ITPS applications.

14 CFR 25.397 - Control system loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Control system loads. 25.397 Section 25.397 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loads. (a) General. The maximum and minimum pilot forces, specified in paragraph (c) of this section...

14 CFR 25.397 - Control system loads.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Control system loads. 25.397 Section 25.397 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loads. (a) General. The maximum and minimum pilot forces, specified in paragraph (c) of this section...

14 CFR 25.397 - Control system loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Control system loads. 25.397 Section 25.397 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loads. (a) General. The maximum and minimum pilot forces, specified in paragraph (c) of this section...

14 CFR 25.397 - Control system loads.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Control system loads. 25.397 Section 25.397 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loads. (a) General. The maximum and minimum pilot forces, specified in paragraph (c) of this section...

14 CFR 25.397 - Control system loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Control system loads. 25.397 Section 25.397 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loads. (a) General. The maximum and minimum pilot forces, specified in paragraph (c) of this section...

Automation in the Space Station module power management and distribution Breadboard

NASA Technical Reports Server (NTRS)

Walls, Bryan; Lollar, Louis F.

1990-01-01

The Space Station Module Power Management and Distribution (SSM/PMAD) Breadboard, located at NASA's Marshall Space Flight Center (MSFC) in Huntsville, Alabama, models the power distribution within a Space Station Freedom Habitation or Laboratory module. Originally designed for 20 kHz ac power, the system is now being converted to high voltage dc power with power levels on a par with those expected for a space station module. In addition to the power distribution hardware, the system includes computer control through a hierarchy of processes. The lowest level process consists of fast, simple (from a computing standpoint) switchgear, capable of quickly safing the system. The next level consists of local load center processors called Lowest Level Processors (LLP's). These LLP's execute load scheduling, perform redundant switching, and shed loads which use more than scheduled power. The level above the LLP's contains a Communication and Algorithmic Controller (CAC) which coordinates communications with the highest level. Finally, at this highest level, three cooperating Artificial Intelligence (AI) systems manage load prioritization, load scheduling, load shedding, and fault recovery and management. The system provides an excellent venue for developing and examining advanced automation techniques. The current system and the plans for its future are examined.

Review of Full-Scale Docking Seal Testing Capabilities

NASA Technical Reports Server (NTRS)

Dunlap, Patrick H., Jr.; Penney, Nicholas; Wasowski, Janice L.; Daniels, Christopher C.; Steinetz, Bruce M.

2008-01-01

NASA is developing a new docking system to support future space exploration missions to low-Earth orbit, the Moon, and Mars. This mechanism, called the Low Impact Docking System (LIDS), is designed to connect pressurized space vehicles and structures including the Crew Exploration Vehicle, International Space Station, and lunar lander. NASA Glenn Research Center (GRC) is playing a key role in developing the main interface seal for this new docking system. These seals will be approximately 147 cm (58 in.) in diameter. To evaluate the performance of the seals under simulated operating conditions, NASA GRC is developing two new test rigs: a non-actuated version that will be used to measure seal leak rates and an actuated test rig that will be able to measure both seal leak rates and loads. Both test rigs will be able to evaluate the seals under seal-on-seal or seal-on-plate configurations at temperatures from -50 to 50 C (-58 to 122 F) under operational and pre-flight checkout pressure gradients in both aligned and misaligned conditions.

Response of Jupiter's Aurora to Plasma Mass Loading Rate Monitored by the Hisaki Satellite During Io's Volcanic Event

NASA Astrophysics Data System (ADS)

Kimura, T.; Yoshioka, K.; Tsuchiya, F.; Hiraki, Y.; Tao, C.; Murakami, G.; Yamazaki, A.; Fujimoto, M.; Badman, S. V.; Delamere, P. A.; Bagenal, F.

2016-12-01

Plasma production and transfer processes in the planetary and stellar magnetospheres are essential for understanding the space environments around the celestial bodies. It is hypothesized that the mass of plasma loaded from Io's volcano to Jupiter's rotating magnetosphere is recurrently ejected as blobs from the distant tail region of the magnetosphere. The plasma ejections are possibly triggered by the magnetic reconnections, which are followed by the particle energization, bursty planetward plasma flow, and resultant auroral emissions. They are referred to as the 'energetic events'. However, there has been no evidence that the plasma mass loading actually causes the energetic events because of lack of the simultaneous observation of them. This study presents that the recurrent transient auroras, which are possibly representative for the energetic events, are closely associated with the mass loading. Continuous monitoring of the aurora and Io plasma torus indicates onset of the recurrent auroras when accumulation of the loaded plasma mass reaches the canonical total mass of the magnetosphere. This onset condition implies that the fully filled magnetosphere overflows the plasma mass accompanying the energetic events.

Evaluation of digital micromirror devices for use in space-based multiobject spectrometer application

NASA Astrophysics Data System (ADS)

Travinsky, Anton; Vorobiev, Dmitry; Ninkov, Zoran; Raisanen, Alan; Quijada, Manuel A.; Smee, Stephen A.; Pellish, Jonathan A.; Schwartz, Tim; Robberto, Massimo; Heap, Sara; Conley, Devin; Benavides, Carlos; Garcia, Nicholas; Bredl, Zach; Yllanes, Sebastian

2017-07-01

The astronomical community continues to be interested in suitable programmable slit masks for use in multiobject spectrometers (MOSs) on space missions. There have been ground-based MOS utilizing digital micromirror devices (DMDs), and they have proven to be highly accurate and reliable instruments. This paper summarizes the results of a continuing study to investigate the performance of DMDs under conditions associated with space deployment. This includes the response of DMDs to accelerated heavy-ion radiation, to the vibration and mechanical shock loads associated with launch, and the operability of DMD under cryogenic temperatures. The optical contrast ratio and a study of the long-term reflectance of a bare device have also been investigated. The results of the radiation testing demonstrate that DMDs in orbit would experience negligible heavy-ion-induced single event upset (SEU) rate burden; we predict an SEU rate of 5.6 micromirrors/24 h. Vibration and mechanical shock testing was performed according to the NASA General Environmental Verification Standard; there were no failed mirrors in the devices tested. The results of low temperature testing suggest that DMDs are not affected by the thermal load and operate smoothly at temperatures at least as low as 78 K. The reflectivity of a bare DMD did not measurably change even after being exposed to ambient conditions over a period of 13 months even. The measured contrast ratio ("on state" versus "off state" of the DMD micromirrors) was greater than 6000∶1 when illuminated with an f/4 optical beam. Overall DMDs are extremely robust and promise to provide a reliable alternative to microshutter arrays to be used in space as remotely programmable slit masks for MOS design.

Pacific Northwest GridWise™ Testbed Demonstration Projects; Part I. Olympic Peninsula Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammerstrom, Donald J.; Ambrosio, Ron; Carlon, Teresa A.

2008-01-09

This report describes the implementation and results of a field demonstration wherein residential electric water heaters and thermostats, commercial building space conditioning, municipal water pump loads, and several distributed generators were coordinated to manage constrained feeder electrical distribution through the two-way communication of load status and electric price signals. The field demonstration took place in Washington and Oregon and was paid for by the U.S. Department of Energy and several northwest utilities. Price is found to be an effective control signal for managing transmission or distribution congestion. Real-time signals at 5-minute intervals are shown to shift controlled load in time.more » The behaviors of customers and their responses under fixed, time-of-use, and real-time price contracts are compared. Peak loads are effectively reduced on the experimental feeder. A novel application of portfolio theory is applied to the selection of an optimal mix of customer contract types.« less

Dynamic loads on human and animal surrogates at different test locations in compressed-gas-driven shock tubes

NASA Astrophysics Data System (ADS)

Alay, E.; Skotak, M.; Misistia, A.; Chandra, N.

2018-01-01

Dynamic loads on specimens in live-fire conditions as well as at different locations within and outside compressed-gas-driven shock tubes are determined by both static and total blast overpressure-time pressure pulses. The biomechanical loading on the specimen is determined by surface pressures that combine the effects of static, dynamic, and reflected pressures and specimen geometry. Surface pressure is both space and time dependent; it varies as a function of size, shape, and external contour of the specimens. In this work, we used two sets of specimens: (1) anthropometric dummy head and (2) a surrogate rodent headform instrumented with pressure sensors and subjected them to blast waves in the interior and at the exit of the shock tube. We demonstrate in this work that while inside the shock tube the biomechanical loading as determined by various pressure measures closely aligns with live-fire data and shock wave theory, significant deviations are found when tests are performed outside.

Experimental investigation on a high head model Francis turbine during load rejection

NASA Astrophysics Data System (ADS)

Goyal, R.; Bergan, C.; Cervantes, M. J.; Gandhi, B. K.; Dahlhaug, O. G.

2016-11-01

Francis-99 is a set of workshop aiming to determine the state of the art of high head model Francis turbine simulations (flow and structure) under steady and transient operating conditions as well as to promote their development and knowledge dissemination openly. The first workshop (Trondheim, 2014) was concerned with steady state operation. The second workshop will focus on transient operations such as load variation and start-stop. In the present work, 2-D particle image velocimetry (PIV) with synchronized pressure measurements performed in the draft tube cone of the Francis-99 test case during load rejection is presented. Pressure sensors were mounted in the vaneless space and draft tube cone to estimate the instantaneous pressure fluctuations while operating the turbine from the best efficiency point (9.8°) to part load (6.7°) with the presence of a rotating vortex rope (RVR). The time-resolved velocity and pressure data are presented in this paper showing the transition in the turbine from one state to another.

Geometry Design Optimization of Functionally Graded Scaffolds for Bone Tissue Engineering: A Mechanobiological Approach.

PubMed

Boccaccio, Antonio; Uva, Antonio Emmanuele; Fiorentino, Michele; Mori, Giorgio; Monno, Giuseppe

2016-01-01

Functionally Graded Scaffolds (FGSs) are porous biomaterials where porosity changes in space with a specific gradient. In spite of their wide use in bone tissue engineering, possible models that relate the scaffold gradient to the mechanical and biological requirements for the regeneration of the bony tissue are currently missing. In this study we attempt to bridge the gap by developing a mechanobiology-based optimization algorithm aimed to determine the optimal graded porosity distribution in FGSs. The algorithm combines the parametric finite element model of a FGS, a computational mechano-regulation model and a numerical optimization routine. For assigned boundary and loading conditions, the algorithm builds iteratively different scaffold geometry configurations with different porosity distributions until the best microstructure geometry is reached, i.e. the geometry that allows the amount of bone formation to be maximized. We tested different porosity distribution laws, loading conditions and scaffold Young's modulus values. For each combination of these variables, the explicit equation of the porosity distribution law-i.e the law that describes the pore dimensions in function of the spatial coordinates-was determined that allows the highest amounts of bone to be generated. The results show that the loading conditions affect significantly the optimal porosity distribution. For a pure compression loading, it was found that the pore dimensions are almost constant throughout the entire scaffold and using a FGS allows the formation of amounts of bone slightly larger than those obtainable with a homogeneous porosity scaffold. For a pure shear loading, instead, FGSs allow to significantly increase the bone formation compared to a homogeneous porosity scaffolds. Although experimental data is still necessary to properly relate the mechanical/biological environment to the scaffold microstructure, this model represents an important step towards optimizing geometry of functionally graded scaffolds based on mechanobiological criteria.

Vestibular-Somatosensory Convergence in Head Movement Control During Locomotion after Long-Duration Space Flight

NASA Technical Reports Server (NTRS)

Mulavara, Ajitkumar; Ruttley, Tara; Cohen, Helen; Peters, Brian; Miller, Chris; Brady, Rachel; Merkle, Lauren; Bloomberg, Jacob

2010-01-01

Exposure to the microgravity conditions of space flight induces adaptive modification in the control of vestibular-mediated reflexive head movement during locomotion after space flight. Space flight causes astronauts to be exposed to somatosensory adaptation in both the vestibular and body load-sensing (BLS) systems. The goal of these studies was to examine the contributions of vestibular and BLS-mediated somatosensory influences on head movement control during locomotion after long-duration space flight. Subjects were asked to walk on a treadmill driven at 1.8 m/s while performing a visual acuity task. Data were collected using the same testing protocol from three independent subject groups; 1) normal subjects before and after exposure to 30 minutes of 40% bodyweight unloaded treadmill walking, 2) bilateral labyrinthine deficient (LD) patients and 3) astronauts who performed the protocol before and after long duration space flight. Motion data from head and trunk segmental motion data were obtained to calculate the angular head pitch (HP) movements during walking trials while subjects performed the visual task, to estimate the contributions of vestibular reflexive mechanisms in HP movements. Results showed that exposure to unloaded locomotion caused a significant increase in HP movements, whereas in the LD patients the HP movements were significantly decreased. Astronaut subjects results showed a heterogeneous response of both increases and decreases in the amplitude of HP movement. We infer that BLS-mediated somatosensory input centrally modulates vestibular input and can adaptively modify head-movement control during locomotion. Thus, space flight may cause a central adaptation mediated by the converging vestibular and body load-sensing somatosensory systems.

14 CFR 23.507 - Jacking loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Jacking loads. 23.507 Section 23.507 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... inertia forces so as to result in no change in the direction of the resultant loads at the jack points. (c...

Berthing simulator for space station and orbiter

NASA Technical Reports Server (NTRS)

Veerasamy, Sam

1991-01-01

The development of a real-time man-in-the-loop berthing simulator is in progress at NASA Lyndon B. Johnson Space Center (JSC) to conduct a parametric study and to measure forces during contact conditions of the actual docking mechanisms for the Space Station Freedom and the orbiter. In berthing, the docking ports of the Space Station and the orbiter are brought together using the orbiter robotic arm to control the relative motion of the vehicles. The berthing simulator consists of a dynamics docking test system (DDTS), computer system, simulator software, and workstations. In the DDTS, the Space Station, and the orbiter docking mechanisms are mounted on a six-degree-of-freedom (6 DOF) table and a fixed platform above the table. Six load cells are used on the fixed platform to measure forces during contact conditions of the docking mechanisms. Two Encore Concept 32/9780 computers are used to simulate the orbiter robotic arm and to operate the berthing simulator. A systematic procedure for a real-time dynamic initialization is being developed to synchronize the Space Station docking port trajectory with the 6 DOF table movement. The berthing test can be conducted manually or automatically and can be extended for any two orbiting vehicles using a simulated robotic arm. The real-time operation of the berthing simulator is briefly described.

Grounding of space structures

NASA Astrophysics Data System (ADS)

Bosela, P. A.; Fertis, D. G.; Shaker, F. J.

1992-09-01

Space structures, such as the Space Station solar arrays, must be extremely light-weight, flexible structures. Accurate prediction of the natural frequencies and mode shapes is essential for determining the structural adequacy of components, and designing a controls system. The tension pre-load in the 'blanket' of photovoltaic solar collectors, and the free/free boundary conditions of a structure in space, causes serious reservations on the use of standard finite element techniques of solution. In particular, a phenomenon known as 'grounding', or false stiffening, of the stiffness matrix occurs during rigid body rotation. This paper examines the grounding phenomenon in detail. Numerous stiffness matrices developed by others are examined for rigid body rotation capability, and found lacking. A force imbalance inherent in the formulations examined is the likely cause of the grounding problem, suggesting the need for a directed force formulation.

Managing the space-time-load continuum in TMDL planning: a case study for understanding groundwaer loads through advanced mapping techniques

Treesearch

Phillip Harte; Marcel Belaval; Andrea Traviglia

2016-01-01

The lag time between groundwater recharge and discharge in a watershed and the potential groundwater load to streams is an important factor in forecasting responses to future land use practices. We call this concept managing the “space-time-load continuum.” It’s understood that in any given watershed, the response function (the load at any given time) will differ for...

Water Impact Prediction Tool for Recoverable Rockets

NASA Technical Reports Server (NTRS)

Rooker, William; Glaese, John; Clayton, Joe

2011-01-01

Reusing components from a rocket launch can be cost saving. NASA's space shuttle system has reusable components that return to the Earth and impact the ocean. A primary example is the Space Shuttle Solid Rocket Booster (SRB) that descends on parachutes to the Earth after separation and impacts the ocean. Water impact generates significant structural loads that can damage the booster, so it is important to study this event in detail in the design of the recovery system. Some recent examples of damage due to water impact include the Ares I-X First Stage deformation as seen in Figure 1 and the loss of the SpaceX Falcon 9 First Stage.To ensure that a component can be recovered or that the design of the recovery system is adequate, an adequate set of structural loads is necessary for use in failure assessments. However, this task is difficult since there are many conditions that affect how a component impacts the water and the resulting structural loading that a component sees. These conditions include the angle of impact with respect to the water, the horizontal and vertical velocities, the rotation rate, the wave height and speed, and many others. There have been attempts to simulate water impact. One approach is to analyze water impact using explicit finite element techniques such as those employed by the LS-Dyna tool [1]. Though very detailed, this approach is time consuming and would not be suitable for running Monte Carlo or optimization analyses. The purpose of this paper is to describe a multi-body simulation tool that runs quickly and that captures the environments a component might see. The simulation incorporates the air and water interaction with the component, the component dynamics (i.e. modes and mode shapes), any applicable parachutes and lines, the interaction of winds and gusts, and the wave height and speed. It is capable of quickly conducting Monte Carlo studies to better capture the environments and genetic algorithm optimizations to reproduce a flight.

In situ nonlinear ultrasonic technique for monitoring microcracking in concrete subjected to creep and cyclic loading.

PubMed

Kim, Gun; Loreto, Giovanni; Kim, Jin-Yeon; Kurtis, Kimberly E; Wall, James J; Jacobs, Laurence J

2018-08-01

This research conducts in situ nonlinear ultrasonic (NLU) measurements for real time monitoring of load-induced damage in concrete. For the in situ measurements on a cylindrical specimen under sustained load, a previously developed second harmonic generation (SHG) technique with non-contact detection is adapted to a cylindrical specimen geometry. This new setup is validated by demonstrating that the measured nonlinear Rayleigh wave signals are equivalent to those in a flat half space, and thus the acoustic nonlinearity parameter, β can be defined and interpreted in the same way. Both the acoustic nonlinearity parameter and strain are measured to quantitatively assess the early-age damage in a set of concrete specimens subjected to either 25 days of creep, or 11 cycles of cyclic loading at room temperature. The experimental results show that the acoustic nonlinearity parameter is sensitive to early-stage microcrack formation under both loading conditions - the measured β can be directly linked to the accumulated microscale damage. This paper demonstrates the potential of NLU for the in situ monitoring of mechanical load-induced microscale damage in concrete components. Copyright © 2018 Elsevier B.V. All rights reserved.

Strategy Guideline: HVAC Equipment Sizing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burdick, A.

The heating, ventilation, and air conditioning (HVAC) system is arguably the most complex system installed in a house and is a substantial component of the total house energy use. A right-sized HVAC system will provide the desired occupant comfort and will run efficiently. This Strategy Guideline discusses the information needed to initially select the equipment for a properly designed HVAC system. Right-sizing of an HVAC system involves the selection of equipment and the design of the air distribution system to meet the accurate predicted heating and cooling loads of the house. Right-sizing the HVAC system begins with an accurate understandingmore » of the heating and cooling loads on a space; however, a full HVAC design involves more than just the load estimate calculation - the load calculation is the first step of the iterative HVAC design procedure. This guide describes the equipment selection of a split system air conditioner and furnace for an example house in Chicago, IL as well as a heat pump system for an example house in Orlando, Florida. The required heating and cooling load information for the two example houses was developed in the Department of Energy Building America Strategy Guideline: Accurate Heating and Cooling Load Calculations.« less

Wet in situ transesterification of spent coffee grounds with supercritical methanol for the production of biodiesel.

PubMed

Son, Jeesung; Kim, Bora; Park, Jeongseok; Yang, Jeongwoo; Lee, Jae W

2018-07-01

This work introduces biodiesel production from wet spent coffee grounds (SCGs) with supercritical methanol without any pre-drying process. Supercritical methanol and subcritical water effectively produced biodiesel via in situ transesterification by inducing more porous SCG and enhancing the efficiency of lipid extraction and conversion. It was also found that space loading was one of the critical factors for biodiesel production. An optimal biodiesel yield of 10.17 wt% of dry SCG mass (86.33 w/w% of esterifiable lipids in SCG) was obtained at reaction conditions of 270 °C, 90 bars, methanol to wet SCG ratio 5:1, space loading 58.4 ml/g and reaction time 20 min. Direct use of wet SCG waste as feedstock for supercritical biodiesel production eliminates the conventional dying process and the need of catalyst and also reduces environmental problems caused by landfill accumulation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Test Report for MSFC Test No. 83-2: Pressure scaled water impact test of a 12.5 inch diameter model of the Space Shuttle solid rocket booster filament wound case and external TVC PCD

NASA Technical Reports Server (NTRS)

1983-01-01

Water impact tests using a 12.5 inch diameter model representing a 8.56 percent scale of the Space Shuttle Solid Rocket Booster configuration were conducted. The two primary objectives of this SRB scale model water impact test program were: 1. Obtain cavity collapse applied pressure distributions for the 8.56 percent rigid body scale model FWC pressure magnitudes as a function of full-scale initial impact conditions at vertical velocities from 65 to 85 ft/sec, horizontal velocities from 0 to 45 ft/sec, and angles from -10 to +10 degrees. 2. Obtain rigid body applied pressures on the TVC pod and aft skirt internal stiffener rings at initial impact and cavity collapse loading events. In addition, nozzle loads were measured. Full scale vertical velocities of 65 to 85 ft/sec, horizontal velocities of 0 to 45 ft/sec, and impact angles from -10 to +10 degrees simulated.

Performance of Subscale Docking Seals Under Simulated Temperature Conditions

NASA Technical Reports Server (NTRS)

Smith, Ian M.; Daniels, Christopher C.

2008-01-01

A universal docking system is being developed by the National Aeronautics and Space Administration (NASA) to support future space exploration missions to low Earth orbit (LEO), to the moon, and to Mars. The candidate docking seals for the system are a composite design consisting of elastomer seal bulbs molded into the front and rear sides of a metal ring. The test specimens were subscale seals with two different elastomer cross-sections and a 12-in. outside diameter. The seal assemblies were mated in elastomer seal-on-metal plate and elastomer seal-on-elastomer seal configurations. The seals were manufactured from S0383-70 silicone elastomer compound. Nominal and off-nominal joint configurations were examined. Both the compression load required to mate the seals and the leak rate observed were recorded while the assemblies were subjected to representative docking system operating temperatures of -58, 73, and 122 F (-50, 23, and 50 C). Both the loads required to fully compress the seals and their leak rates were directly proportional to the test temperature.

Space shuttle prototype check valve development

NASA Technical Reports Server (NTRS)

Tellier, G. F.

1976-01-01

Contaminant-resistant seal designs and a dynamically stable prototype check valve for the orbital maneuvering and reaction control helium pressurization systems of the space shuttle were developed. Polymer and carbide seal models were designed and tested. Perfluoroelastomers compatible with N2O4 and N2H4 types were evaluated and compared with Teflon in flat and captive seal models. Low load sealing and contamination resistance tests demonstrated cutter seal superiority over polymer seals. Ceramic and carbide materials were evaluated for N2O4 service using exposure to RFNA as a worst case screen; chemically vapor deposited tungsten carbide was shown to be impervious to the acid after 6 months immersion. A unique carbide shell poppet/cutter seat check valve was designed and tested to demonstrate low cracking pressure ( 2.0 psid), dynamic stability under all test bench flow conditions, contamination resistance (0.001 inch CRES wires cut with 1.5 pound seat load) and long life of 100,000 cycles (leakage 1.0 scc/hr helium from 0.1 to 400 psig).

Evaluation of dispersion strengthened nickel-base alloy heat shields for space shuttle application

NASA Technical Reports Server (NTRS)

Johnson, R., Jr.; Killpatrick, D. H.

1976-01-01

The results obtained in a program to evaluate dispersion-strengthened nickel-base alloys for use in a metallic radiative thermal protection system operating at surface temperatures to 1477 K for the space shuttle were presented. Vehicle environments having critical effects on the thermal protection system are defined; TD Ni-20Cr characteristics of material used in the current study are compared with previous results; cyclic load, temperature, and pressure effects on sheet material residual strength are investigated; the effects of braze reinforcement in improving the efficiency of spotwelded joints are evaluated; parametric studies of metallic radiative thermal protection systems are reported; and the design, instrumentation, and testing of full scale subsize heat shield panels in two configurations are described. Initial tests of full scale subsize panels included simulated meteoroid impact tests, simulated entry flight aerodynamic heating, programmed differential pressure loads and temperatures simulating mission conditions, and acoustic tests simulating sound levels experienced during boost flight.

Composite Load Spectra for Select Space Propulsion Structural Components

NASA Technical Reports Server (NTRS)

Ho, Hing W.; Newell, James F.

1994-01-01

Generic load models are described with multiple levels of progressive sophistication to simulate the composite (combined) load spectra (CLS) that are induced in space propulsion system components, representative of Space Shuttle Main Engines (SSME), such as transfer ducts, turbine blades and liquid oxygen (LOX) posts. These generic (coupled) models combine the deterministic models for composite load dynamic, acoustic, high-pressure and high rotational speed, etc., load simulation using statistically varying coefficients. These coefficients are then determined using advanced probabilistic simulation methods with and without strategically selected experimental data. The entire simulation process is included in a CLS computer code. Applications of the computer code to various components in conjunction with the PSAM (Probabilistic Structural Analysis Method) to perform probabilistic load evaluation and life prediction evaluations are also described to illustrate the effectiveness of the coupled model approach.

Characteristics of Subcooled Liquid Methane During Passage Through a Spray-Bar Joule-Thompson Thermodynamic Vent System

NASA Technical Reports Server (NTRS)

Hastings, L. J.; Bolshinskiy, L. G.; Hedayat, A.; Schnell, A.

2011-01-01

NASA s Marshall Space Flight Center (MSFC) conducted liquid methane (LCH4) testing in November 2006 using the multipurpose hydrogen test bed (MHTB) outfitted with a spray-bar thermodynamic vent system (TVS). The basic objective was to identify any unusual or unique thermodynamic characteristics associated with subcooled LCH4 that should be considered in the design of space-based TVSs. Thirteen days of testing were performed with total tank heat loads ranging from 720 W to 420 W at a fill level of approximately 90%. During an updated evaluation of the data, it was noted that as the fluid passed through the Joule Thompson expansion, thermodynamic conditions consistent with the pervasive presence of metastability were indicated. This paper describes the observed thermodynamic conditions that correspond with metastability and effects on TVS performance.

Space shuttle SRM plume expansion sensitivity analysis. [flow characteristics of exhaust gases from solid propellant rocket engines

NASA Technical Reports Server (NTRS)

Smith, S. D.; Tevepaugh, J. A.; Penny, M. M.

1975-01-01

The exhaust plumes of the space shuttle solid rocket motors can have a significant effect on the base pressure and base drag of the shuttle vehicle. A parametric analysis was conducted to assess the sensitivity of the initial plume expansion angle of analytical solid rocket motor flow fields to various analytical input parameters and operating conditions. The results of the analysis are presented and conclusions reached regarding the sensitivity of the initial plume expansion angle to each parameter investigated. Operating conditions parametrically varied were chamber pressure, nozzle inlet angle, nozzle throat radius of curvature ratio and propellant particle loading. Empirical particle parameters investigated were mean size, local drag coefficient and local heat transfer coefficient. Sensitivity of the initial plume expansion angle to gas thermochemistry model and local drag coefficient model assumptions were determined.

Electric Power Load Analysis (EPLA) for Surface Ships

DTIC Science & Technology

2012-09-17

112 - Shipping: Emergency Lighting And Power Systems (Copies of this document are available from the Superintendent of Documents, U.S. Government...number of (dry bulb ) temperature/relative humidity ambient conditions and an associated percentage of time the ship is spent operating in the particular...propulsion cannot be otherwise restored in less than 2 minutes. c. Machinery space class W and circle W ventilation. d. Emergency lighting . DDS 310-1

Plasma torch testing for thermostructural evaluation of rocket motor nozzle materials

NASA Technical Reports Server (NTRS)

Prince, Andrew S.; Bunker, Robert C.; Lawrence, Tim

1989-01-01

This paper presents data from the thermostructural testing of tape-wrapped carbon phenolic. This work has been performed with the use of a plasma torch and loading device in an effort to study the anomalous erosion characteristicfs of that seen in the Space Shuttle Solid Rocket Motor Nozzle STS-8A. Testing is conducted in an effort to determine conditions or parameters involved in this mode of failure.

Experiment Evaluation of Bifurcation in Sands

NASA Technical Reports Server (NTRS)

Alshibi, Khalid A.; Sture, Stein

2000-01-01

The basic principles of bifurcation analysis have been established by several investigators, however several issues remain unresolved, specifically how do stress level, grain size distribution, and boundary conditions affect general bifurcation phenomena in pressure sensitive and dilatant materials. General geometrical and kinematics conditions for moving surfaces of discontinuity was derived and applied to problems of instability of solids. In 1962, the theoretical framework of bifurcation by studying the acceleration waves in elasto-plastic (J2) solids were presented. Bifurcation analysis for more specific forms of constitutive behavior was examined by studying localization in pressure-sensitive, dilatant materials, however, analyses were restricted to plane deformation states only. Bifurcation analyses were presented and applied to predict shear band formations in sand under plane strain condition. The properties of discontinuous bifurcation solutions for elastic-plastic solids under axisymmetric and plane strain loading conditions were studied. The study focused on theory, but also references and comparisons to experiments were made. The current paper includes a presentation of a summary of bifurcation analyses for biaxial and triaxial (axisymmetric) loading conditions. The Coulomb model is implemented using incremental piecewise scheme to predict the constitutive relations and shear band inclination angles. Then, a comprehensive evaluation of bifurcation phenomena is presented based on data from triaxial experiments performed under microgravity conditions aboard the Space Shuttle under very low effective confining pressure (0.05 to 1.30 kPa), in which very high peak friction angles (47 to 75 degrees) and dilatancy angles (30 to 31 degrees) were measured. The evaluation will be extended to include biaxial experiments performed on the same material under low (10 kPa) and moderate (100 kPa) confining pressures. A comparison between the behavior under biaxial and triaxial loading conditions will be presented, and related issues concerning influence of confining pressure will be discussed.

A new pre-loaded beam geometric stiffness matrix with full rigid body capabilities

NASA Astrophysics Data System (ADS)

Bosela, P. A.; Fertis, D. G.; Shaker, F. J.

1992-09-01

Space structures, such as the Space Station solar arrays, must be extremely light-weight, flexible structures. Accurate prediction of the natural frequencies and mode shapes is essential for determining the structural adequacy of components, and designing a controls system. The tension pre-load in the 'blanket' of photovoltaic solar collectors, and the free/free boundary conditions of a structure in space, causes serious reservations on the use of standard finite element techniques of solution. In particular, a phenomenon known as 'grounding', or false stiffening, of the stiffness matrix occurs during rigid body rotation. The authors have previously shown that the grounding phenomenon is caused by a lack of rigid body rotational capability, and is typical in beam geometric stiffness matrices formulated by others, including those which contain higher order effects. The cause of the problem was identified as the force imbalance inherent in the formulations. In this paper, the authors develop a beam geometric stiffness matrix for a directed force problem, and show that the resultant global stiffness matrix contains complete rigid body mode capabilities, and performs very well in the diagonalization methodology customarily used in dynamic analysis.

Thermoregulatory models of safety-for-flight issues for space operations

NASA Astrophysics Data System (ADS)

Pisacane, V. L.; Kuznetz, L. H.; Logan, J. S.; Clark, J. B.; Wissler, E. H.

2006-10-01

This study investigates the use of a mathematical model for thermoregulation as a tool in safety-of-flight issues and proposed solutions for mission operations of the Space Shuttle and the International Space Station. Specifically, this study assesses the effects of elevated cabin temperature and metabolic loads on astronauts wearing the Advanced Crew Escape Suit (ACES) and the Liquid Cooled Ventilation Garment (LCVG). The 225-node Wissler model is validated by comparison with two ground-based human subject tests, firefighters, and surrogate astronauts under anomalous conditions that show good agreement. Subsequent simulations indicate that the performance of the ACES/LCVG is marginal. Increases in either workload or cabin temperature from the nominal will increase rectal temperature, stored heat load, heart rate, and sweating leading to possible deficits in the ability of the astronauts to perform cognitive and motor tasks that could affect the safety of the mission, especially the safe landing of the Shuttle. Specific relationships are given between cabin temperature and metabolic rate that define the threshold for decreased manual dexterity and loss of tracking skills. Model results indicate that the most effective mitigation strategy would be to decrease the LCVG inlet temperature. Methods of accomplishing this are also proposed.

Data Sciences Summer Institute Topology Optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watts, Seth

DSSI_TOPOPT is a 2D topology optimization code that designs stiff structures made of a single linear elastic material and void space. The code generates a finite element mesh of a rectangular design domain on which the user specifies displacement and load boundary conditions. The code iteratively designs a structure that minimizes the compliance (maximizes the stiffness) of the structure under the given loading, subject to an upper bound on the amount of material used. Depending on user options, the code can evaluate the performance of a user-designed structure, or create a design from scratch. Output includes the finite element mesh,more » design, and visualizations of the design.« less

Considerations in STS payload environmental verification

NASA Technical Reports Server (NTRS)

Keegan, W. B.

1978-01-01

Considerations regarding the Space Transportation System (STS) payload environmental verification are reviewed. It is noted that emphasis is placed on testing at the subassembly level and that the basic objective of structural dynamic payload verification is to ensure reliability in a cost-effective manner. Structural analyses consist of: (1) stress analysis for critical loading conditions, (2) model analysis for launch and orbital configurations, (3) flight loads analysis, (4) test simulation analysis to verify models, (5) kinematic analysis of deployment/retraction sequences, and (6) structural-thermal-optical program analysis. In addition to these approaches, payload verification programs are being developed in the thermal-vacuum area. These include the exposure to extreme temperatures, temperature cycling, thermal-balance testing and thermal-vacuum testing.

Effects of running with backpack loads during simulated gravitational transitions: Improvements in postural control

NASA Astrophysics Data System (ADS)

Brewer, Jeffrey David

The National Aeronautics and Space Administration is planning for long-duration manned missions to the Moon and Mars. For feasible long-duration space travel, improvements in exercise countermeasures are necessary to maintain cardiovascular fitness, bone mass throughout the body and the ability to perform coordinated movements in a constant gravitational environment that is six orders of magnitude higher than the "near weightlessness" condition experienced during transit to and/or orbit of the Moon, Mars, and Earth. In such gravitational transitions feedback and feedforward postural control strategies must be recalibrated to ensure optimal locomotion performance. In order to investigate methods of improving postural control adaptation during these gravitational transitions, a treadmill based precision stepping task was developed to reveal changes in neuromuscular control of locomotion following both simulated partial gravity exposure and post-simulation exercise countermeasures designed to speed lower extremity impedance adjustment mechanisms. The exercise countermeasures included a short period of running with or without backpack loads immediately after partial gravity running. A novel suspension type partial gravity simulator incorporating spring balancers and a motor-driven treadmill was developed to facilitate body weight off loading and various gait patterns in both simulated partial and full gravitational environments. Studies have provided evidence that suggests: the environmental simulator constructed for this thesis effort does induce locomotor adaptations following partial gravity running; the precision stepping task may be a helpful test for illuminating these adaptations; and musculoskeletal loading in the form of running with or without backpack loads may improve the locomotor adaptation process.

Development and performance evaluation of a three-dimensional clinostat synchronized heavy-ion irradiation system.

PubMed

Ikeda, Hiroko; Souda, Hikaru; Puspitasari, Anggraeini; Held, Kathryn D; Hidema, Jun; Nikawa, Takeshi; Yoshida, Yukari; Kanai, Tatsuaki; Takahashi, Akihisa

2017-02-01

Outer space is an environment characterized by microgravity and space radiation, including high-energy charged particles. Astronauts are constantly exposed to both microgravity and radiation during long-term stays in space. However, many aspects of the biological effects of combined microgravity and space radiation remain unclear. We developed a new three-dimensional (3D) clinostat synchronized heavy-ion irradiation system for use in ground-based studies of the combined exposures. Our new system uses a particle accelerator and a respiratory gating system from heavy-ion radiotherapy to irradiate samples being rotated in the 3D clinostat with carbon-ion beams only when the samples are in the horizontal position. A Peltier module and special sample holder were loaded on a static stage (standing condition) and the 3D clinostat (rotation condition) to maintain a suitable temperature under atmospheric conditions. The performance of the new device was investigated with normal human fibroblasts 1BR-hTERT in a disposable closed cell culture chamber. Live imaging revealed that cellular adhesion and growth were almost the same for the standing control sample and rotation sample over 48h. Dose flatness and symmetry were judged according to the relative density of Gafchromic films along the X-axis and Y-axis of the positions of the irradiated sample to confirm irradiation accuracy. Doses calculated using the carbon-ion calibration curve were almost the same for standing and rotation conditions, with the difference being less than 5% at 1Gy carbon-ion irradiation. Our new device can accurately synchronize carbon-ion irradiation and simulated microgravity while maintaining the temperature under atmospheric conditions at ground level. Copyright © 2017 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

Prospective, randomized and controlled trial on magnesium sulfate administration during laparoscopic gastrectomy: effects on surgical space conditions and recovery profiles.

PubMed

Ryu, J H; Koo, B W; Kim, B G; Oh, A Y; Kim, H H; Park, D J; Lee, C M; Kim, S T; Do, S H

2016-11-01

The degree of neuromuscular blockade is one of the important factors that determine the condition of surgical space during laparoscopic surgery. Magnesium sulfate potentiates the actions of neuromuscular blocking agent, and we hypothesized that intraoperative magnesium sulfate infusion may improve surgical space condition during laparoscopic surgery. Eighty-four patients undergoing elective laparoscopic gastrectomy were randomized to receive isotonic saline (group C) or magnesium sulfate (group M, loading dose with 50 mg/kg over 10 min and then 15 mg/kg/h by continuous infusion) to maintain the moderate neuromuscular blockade using rocuronium. Two experienced surgeons scored the quality of surgical space condition using a 5-point surgical rating scale (SRS). The secondary outcomes included recovery profiles, postoperative pain and adverse events. The SRS in group M was higher than that of group C. The proportion of patients with a SRS of 5 (optimal) was 2.7 % in the group C and 40.5 % in the group M (P < 0.0001) although a lower amount of rocuronium was required in group M than group C [24.2 (6.5) mg/h for group M vs. 27.5 (6) mg/h for group C; P = 0.017]. Pain after operation site was less severe in group M than in group C at postoperative 24 h (P = 0.009). Recovery profiles and adverse events were similar between the two groups. Intraoperative administration of magnesium sulfate improved the quality of surgical space conditions and decreased neuromuscular blocking agent requirement and postoperative pain in patients undergoing laparoscopic gastrectomy.

Nonlinear Analysis and Post-Test Correlation for a Curved PRSEUS Panel

NASA Technical Reports Server (NTRS)

Gould, Kevin; Lovejoy, Andrew E.; Jegley, Dawn; Neal, Albert L.; Linton, Kim, A.; Bergan, Andrew C.; Bakuckas, John G., Jr.

2013-01-01

The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept, developed by The Boeing Company, has been extensively studied as part of the National Aeronautics and Space Administration's (NASA s) Environmentally Responsible Aviation (ERA) Program. The PRSEUS concept provides a light-weight alternative to aluminum or traditional composite design concepts and is applicable to traditional-shaped fuselage barrels and wings, as well as advanced configurations such as a hybrid wing body or truss braced wings. Therefore, NASA, the Federal Aviation Administration (FAA) and The Boeing Company partnered in an effort to assess the performance and damage arrestments capabilities of a PRSEUS concept panel using a full-scale curved panel in the FAA Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility. Testing was conducted in the FASTER facility by subjecting the panel to axial tension loads applied to the ends of the panel, internal pressure, and combined axial tension and internal pressure loadings. Additionally, reactive hoop loads were applied to the skin and frames of the panel along its edges. The panel successfully supported the required design loads in the pristine condition and with a severed stiffener. The panel also demonstrated that the PRSEUS concept could arrest the progression of damage including crack arrestment and crack turning. This paper presents the nonlinear post-test analysis and correlation with test results for the curved PRSEUS panel. It is shown that nonlinear analysis can accurately calculate the behavior of a PRSEUS panel under tension, pressure and combined loading conditions.

Improving English Learners' Productive Collocation Knowledge: The Effects of Involvement Load, Spacing, and Intentionality

ERIC Educational Resources Information Center

Snoder, Per

2017-01-01

This article reports on a classroom-based experiment that tested the effects of three vocabulary teaching constructs (involvement load, spacing, and intentionality) on the learning of English verb-noun collocations--for example, "shelve a plan." Laufer and Hulstijn's (2001) "involvement load" predicts that the higher the…

Investigation of instability, dynamic forces, and effect of dynamic loading on strength of cages for the bearings in the high pressure oxygen turbopumps for the space shuttle main engine

NASA Technical Reports Server (NTRS)

Dufrane, K. F.; Kannel, J. W.; Merriman, T. L.; Rosenfield, A. R.

1985-01-01

Experiments were performed to determine the effect of cyclic loading on bearing cage strength. A long term working tensile load of approximately 1300 N (300 lbs) was found to be the likely maximum. Higher loads caused a decrease in cage tensile strength after the 125,000 cycle testing period. Poisson's ratio in compression was found to be highly dependent upon the direction of the fiberglass plies. At room temperature the value was 0.15 with the plies and 0.68 across the plies. At -196 C (-321 F), the value with the plies was 0.20. The results of the analyses conducted have again demonstrated the critical need for improved lubrication in the high pressure oxygen turbopump bearings. Lubricant films with low shear strength and low friction coefficients promote cage stability and decrease ball/cage forces during marginal operating conditions. The analysis of the effect of combined bearing loads on ball/cage loads has identified a radial load of 3600 N (800 lbs) as the maximum for the current clearance of the balls and cage pockets. Liquid oxygen impinging on the cage in the direction of rotation was found to enhance cage stability.

Coupled loads analysis for Space Shuttle payloads

NASA Technical Reports Server (NTRS)

Eldridge, J.

1992-01-01

Described here is a method for determining the transient response of, and the resultant loads in, a system exposed to predicted external forces. In this case, the system consists of four racks mounted on the inside of a space station resource node module (SSRNMO) which is mounted in the payload bay of the space shuttle. The predicted external forces are forcing functions which envelope worst case forces applied to the shuttle during liftoff and landing. This analysis, called a coupled loads analysis, is used to couple the payload and shuttle models together, determine the transient response of the system, and then recover payload loads, payload accelerations, and payload to shuttle interface forces.

Design considerations for a Space Shuttle Main Engine turbine blade made of single crystal material

NASA Technical Reports Server (NTRS)

Abdul-Aziz, A.; August, R.; Nagpal, V.

1993-01-01

Nonlinear finite-element structural analyses were performed on the first stage high-pressure fuel turbopump blade of the Space Shuttle Main Engine. The analyses examined the structural response and the dynamic characteristics at typical operating conditions. Single crystal material PWA-1480 was considered for the analyses. Structural response and the blade natural frequencies with respect to the crystal orientation were investigated. The analyses were conducted based on typical test stand engine cycle. Influence of combined thermal, aerodynamic, and centrifugal loadings was considered. Results obtained showed that the single crystal secondary orientation effects on the maximum principal stresses are not highly significant.

KSC-2010-4437

NASA Image and Video Library

2010-08-20

CAPE CANAVERAL, Fla. -- The interior of NASA's new mobile launcher, or ML, support structure is outfitted with solid steel flooring, lights, air conditioning, electrical boxes and sprinkler piping at NASA's Kennedy Space Center in Florida. The 355-foot-tall structure will support NASA's future human spaceflight program. The base of the launcher is lighter than space shuttle mobile launcher platforms so the crawler-transporter can pick up the heavier load of the tower and a taller rocket. The next step will be to add ground support equipment, such as umbilicals and access arms, for future rocket launches. For information on NASA's future plans, visit www.nasa.gov. Photo credit: NASA/Kim Shiflett

KSC-2010-4436

NASA Image and Video Library

2010-08-20

CAPE CANAVERAL, Fla. -- The interior of NASA's new mobile launcher, or ML, support structure is outfitted with solid steel flooring, lights, air conditioning, electrical boxes and sprinkler piping at NASA's Kennedy Space Center in Florida. The 355-foot-tall structure will support NASA's future human spaceflight program. The base of the launcher is lighter than space shuttle mobile launcher platforms so the crawler-transporter can pick up the heavier load of the tower and a taller rocket. The next step will be to add ground support equipment, such as umbilicals and access arms, for future rocket launches. For information on NASA's future plans, visit www.nasa.gov. Photo credit: NASA/Kim Shiflett

Mini-BRU/BIPS foil bearing development

NASA Technical Reports Server (NTRS)

Dobler, F. X.; Miller, L. J.

1978-01-01

The analysis revealed the failure agent to be a combination of poor teflon coating adhesion, a decrease in bearing sway space and, possibly, lack of flushing flow through the bearing. A change in Teflon coating vendors provided substantially improved coating quality and surface finish. The sway space was increased and the cooling bleed flow was adjusted to flush the bearing. These changes were included in a test conducted in the WHL from 6 April to 22 May 1978 which resulted in the completion of 1006.9 hours of operation at temperature and load. Post-test inspection revealed the bearings to be in excellent condition and capable of completing a much longer test.

Fuzzy logic application for modeling man-in-the-loop space shuttle proximity operations. M.S. Thesis - MIT

NASA Technical Reports Server (NTRS)

Brown, Robert B.

1994-01-01

A software pilot model for Space Shuttle proximity operations is developed, utilizing fuzzy logic. The model is designed to emulate a human pilot during the terminal phase of a Space Shuttle approach to the Space Station. The model uses the same sensory information available to a human pilot and is based upon existing piloting rules and techniques determined from analysis of human pilot performance. Such a model is needed to generate numerous rendezvous simulations to various Space Station assembly stages for analysis of current NASA procedures and plume impingement loads on the Space Station. The advantages of a fuzzy logic pilot model are demonstrated by comparing its performance with NASA's man-in-the-loop simulations and with a similar model based upon traditional Boolean logic. The fuzzy model is shown to respond well from a number of initial conditions, with results typical of an average human. In addition, the ability to model different individual piloting techniques and new piloting rules is demonstrated.

International Space Station Electric Power System Performance Code-SPACE

NASA Technical Reports Server (NTRS)

Hojnicki, Jeffrey; McKissock, David; Fincannon, James; Green, Robert; Kerslake, Thomas; Delleur, Ann; Follo, Jeffrey; Trudell, Jeffrey; Hoffman, David J.; Jannette, Anthony;

Development of a Variable-Speed Residential Air-Source Integrated Heat Pump

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rice, C Keith; Shen, Bo; Munk, Jeffrey D

2014-01-01

A residential air-source integrated heat pump (AS-IHP) is under development in partnership with a U.S. manufacturer. A nominal 10.6 kW (3-ton) cooling capacity variable-speed unit, the system provides both space conditioning and water heating. This multi-functional unit can provide domestic water heating (DWH) in either full condensing (FC) (dedicated water heating or simultaneous space cooling and water heating) or desuperheating (DS) operation modes. Laboratory test data were used to calibrate a vapor-compression simulation model for each mode of operation. The model was used to optimize the internal control options for efficiency while maintaining acceptable comfort conditions and refrigerant-side pressures andmore » temperatures within allowable operating envelopes. Annual simulations were performed with the AS-IHP installed in a well-insulated house in five U.S. climate zones. The AS-IHP is predicted to use 45 to 60% less energy than a DOE minimum efficiency baseline system while meeting total annual space conditioning and water heating loads. Water heating energy use is lowered by 60 to 75% in cold to warmer climates, respectively. Plans are to field test the unit in Knoxville, TN.« less

Space Shuttle Day-of-Launch Trajectory Design Operations

NASA Technical Reports Server (NTRS)

Harrington, Brian E.

2011-01-01

A top priority of any launch vehicle is to insert as much mass into the desired orbit as possible. This requirement must be traded against vehicle capability in terms of dynamic control, thermal constraints, and structural margins. The vehicle is certified to specific structural limits which will yield certain performance characteristics of mass to orbit. Some limits cannot be certified generically and must be checked with each mission design. The most sensitive limits require an assessment on the day-of-launch. To further minimize vehicle loads while maximizing vehicle performance, a day-of-launch trajectory can be designed. This design is optimized according to that day s wind and atmospheric conditions, which increase the probability of launch. The day-of-launch trajectory design and verification process is critical to the vehicle s safety. The Day-Of-Launch I-Load Update (DOLILU) is the process by which the National Aeronautics and Space Administration's (NASA) Space Shuttle Program tailors the vehicle steering commands to fit that day s environmental conditions and then rigorously verifies the integrated vehicle trajectory s loads, controls, and performance. This process has been successfully used for almost twenty years and shares many of the same elements with other launch vehicles that execute a day-of-launch trajectory design or day-of-launch trajectory verification. Weather balloon data is gathered at the launch site and transmitted to the Johnson Space Center s Mission Control. The vehicle s first stage trajectory is then adjusted to the measured wind and atmosphere data. The resultant trajectory must satisfy loads and controls constraints. Additionally, these assessments statistically protect for non-observed dispersions. One such dispersion is the change in the wind from the last measured balloon to launch time. This process is started in the hours before launch and is repeated several times as the launch count proceeds. Should the trajectory design not meet all constraint criteria, Shuttle would be No-Go for launch. This Shuttle methodology is very similar to other unmanned launch vehicles. By extension, this method would likely be employed for any future NASA launch vehicle. This paper will review the Shuttle s day-of-launch trajectory optimization and verification operations as an example of a more generic application of day-of-launch design and validation. With Shuttle s retirement, it is fitting to document the current state of this critical process and capture lessons learned to benefit current and future launch vehicle endeavors.

Viscoplastic analysis of an experimental cylindrical thrust chamber liner

NASA Technical Reports Server (NTRS)

Arya, Vinod K.; Arnold, Steven M.

1991-01-01

A viscoplastic stress-strain analysis of an experimental cylindrical thrust chamber is presented. A viscoelastic constitutive model incorporating a single internal state variable that represents kinematic hardening was employed to investigate whether such a viscoplastic model could predict the experimentally observed behavior of the thrust chamber. Two types of loading cycles were considered: a short cycle of 3.5 sec. duration that corresponded to the experiments, and an extended loading cycle of 485.1 sec. duration that is typical of the Space Shuttle Main Engine (SSME) operating cycle. The analysis qualitatively replicated the deformation behavior of the component as observed in experiments designed to simulate SSME operating conditions. The analysis also showed that the mode and location in the component may depend on the loading cycle. The results indicate that using viscoplastic models for structural analysis can lead to a more realistic life assessment of thrust chambers.

Stress analysis for structures with surface cracks

NASA Technical Reports Server (NTRS)

Bell, J. C.

1978-01-01

Two basic forms of analysis, one treating stresses around arbitrarily loaded circular cracks, the other treating stresses due to loads arbitrarily distributed on the surface of a half space, are united by a boundary-point least squares method to obtain analyses for stresses from surface cracks in places or bars. Calculations were for enough cases to show how effects from the crack vary with the depth-to-length ratio, the fractional penetration ratio, the obliquity of the load, and to some extent the fractional span ratio. The results include plots showing stress intensity factors, stress component distributions near the crack, and crack opening displacement patterns. Favorable comparisons are shown with two kinds of independent experiments, but the main method for confirming the results is by wide checking of overall satisfaction of boundary conditions, so that external confirmation is not essential. Principles involved in designing analyses which promote dependability of the results are proposed and illustrated.

Forward Skirt Structural Testing on the Space Launch System (SLS) Program

NASA Technical Reports Server (NTRS)

Lohrer, Joe; Wright, R. D.

2016-01-01

Introduction: (a) Structural testing was performed to evaluate Space Shuttle heritage forward skirts for use on the Space Launch System (SLS) program, (b) Testing was required because SLS loads are approximately 35% greater than shuttle loads; and (c) Two forwards skirts were tested to failure.

Space and time reconstruction of the precessing vortex core in Francis turbine draft tube by 2D-PIV

NASA Astrophysics Data System (ADS)

Favrel, A.; Müller, A.; Landry, C.; Yamamoto, K.; Avellan, F.

2016-11-01

Francis turbines operating at part load conditions experience the development of a high swirling flow at the runner outlet, giving rise to the development of a cavitation precessing vortex rope in the draft tube. The latter acts as an excitation source for the hydro-mechanical system and may jeopardize the system stability if resonance conditions are met. Although many aspects of the part load issue have been widely studied in the past, the accurate stability analysis of hydro-power plants remains challenging. A better understanding of the vortex rope dynamics in a wide range of operating conditions is an important step towards the prediction and the transposition of the pressure fluctuations from reduced to prototype scale. For this purpose, an investigation of the flow velocity fields at the outlet of a Francis turbine reduced scale physical model operating at part load conditions is performed by means of 2D-PIV in three different horizontal cross-sections of the draft tube cone. The measurements are performed in cavitation-free conditions for three values of discharge factor, comprised between 60% and 81% of the value at the Best Efficiency Point. The present article describes a detailed methodology to properly recover the evolution of the velocity fields during one precession cycle by means of phase averaging. The vortex circulation is computed and the vortex trajectory over one typical precession period is finally recovered for each operating point. It is notably shown that below a given value of the discharge factor, the vortex dynamics abruptly change and loose its periodicity and coherence.

The building loads analysis system thermodynamics (BLAST) program, Version 2. 0: input booklet. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sowell, E.

1979-06-01

The Building Loads Analysis and System Thermodynamics (BLAST) program is a comprehensive set of subprograms for predicting energy consumption in buildings. There are three major subprograms: (1) the space load predicting subprogram, which computes hourly space loads in a building or zone based on user input and hourly weather data; (2) the air distribution system simulation subprogram, which uses the computed space load and user inputs describing the building air-handling system to calculate hot water or steam, chilled water, and electric energy demands; and (3) the central plant simulation program, which simulates boilers, chillers, onsite power generating equipment and solarmore » energy systems and computes monthly and annual fuel and electrical power consumption and plant life cycle cost.« less

Effect of residential air-to-air heat and moisture exchangers on indoor humidity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barringer, C.G.; McGugan, C.A.

1989-01-01

A project was undertaken to develop guidelines for the selection of residential heat and moisture recovery ventilation systems (HRVs) in order to maintain an acceptable indoor humidity for various climatic conditions. These guidelines were developed from reviews on ventilation requirements, HRV performance specifications, and from computer modeling. Space conditions within three house/occupancy models for several types of HRV were simulated for three climatic conditions (Lake Charles, LA; Seattle, WA; and Winnipeg, MB) in order to determine the impact of the HRVs on indoor relative humidity and space-conditioning loads. Results show that when reduction of cooling cost is the main consideration,more » exchangers with moisture recovery are preferable to sensible HRVs. For reduction of heating costs, moisture recovery should be done for ventilation rates greater than about 15 L/s and average winter temperatures less than about (minus) 10{degrees}C if internal moisture generation rates are low. For houses with higher ventilation rates and colder average winter temperatures, exchangers with moisture recovery should be used.« less

Solar Absorption Refrigeration System for Air-Conditioning of a Classroom Building in Northern India

NASA Astrophysics Data System (ADS)

Agrawal, Tanmay; Varun; Kumar, Anoop

2015-10-01

Air-conditioning is a basic tool to provide human thermal comfort in a building space. The primary aim of the present work is to design an air-conditioning system based on vapour absorption cycle that utilizes a renewable energy source for its operation. The building under consideration is a classroom of dimensions 18.5 m × 13 m × 4.5 m located in Hamirpur district of Himachal Pradesh in India. For this purpose, cooling load of the building was calculated first by using cooling load temperature difference method to estimate cooling capacity of the air-conditioning system. Coefficient of performance of the refrigeration system was computed for various values of strong and weak solution concentration. In this work, a solar collector is also designed to provide required amount of heat energy by the absorption system. This heat energy is taken from solar energy which makes this system eco-friendly and sustainable. A computer program was written in MATLAB to calculate the design parameters. Results were obtained for various values of solution concentrations throughout the year. Cost analysis has also been carried out to compare absorption refrigeration system with conventional vapour compression cycle based air-conditioners.

Construction strength analysis of landing craft tank conversion to passenger ship using finite element method

NASA Astrophysics Data System (ADS)

Nurul Misbah, Mohammad; Setyawan, Dony; Murti Dananjaya, Wisnu

2018-03-01

This research aims to determine the longitudinal strength of passenger ship which was converted from Landing Craft Tank with 54 m of length as stated by BKI (Biro Klasifikasi Indonesia / Indonesian Classification Bureau). Verification of strength value is done to 4 (four) loading conditions which are (1) empty load condition during sagging wave, (2) empty load condition during hogging wave, (3) full load condition during sagging wave and (4) full load condition during hogging wave. Analysis is done using Finite Element Analysis (FEA) software by modeling the entire part of passenger ship and its loading condition. The back and upfront part of ship centerline were used as the boundary condition. From that analysis it can be concluded that the maximum stress for load condition (1) is 72,393 MPa, 74,792 MPa for load condition (2), 129,92 MPa for load condition (3), and 132,4 MPa for load condition (4). Longitudinal strength of passenger ship fulfilled the criteria of empty load condition having smaller stress value than allowable stress which is 90 MPa, and during full load condition with smaller stress value than allowable stress which is 150 MPa. Analysis on longitudinal strength comparison with entire ship plate thickness variation of ± 2 mm from initial plate was also done during this research. From this research it can be concluded that plate thickness reduction causes the value of longitudinal strength to decrease, while plate thickness addition causes the value of longitudinal strength to increase.

Design and demonstration of a storage-assisted air conditioning system

NASA Astrophysics Data System (ADS)

Rizzuto, J. E.

1981-03-01

The system is a peak-shaving system designed to provide a levelized air conditioning load. The system also requires minimum air conditioner and thermal storage capacity. The storage-assisted air conditioning system uses a Glauber's salt-based phase change material in sausage like containers called CHUBS. The CHUBS are two (2) inches in diameter and 20 inches long. They are stacked in modules of 64 CHUBS which are appropriately spaced and oriented in the storage system so that air may pass perpendicular to the long axis of the CHUBS. The phase change material, has a thermal storage capacity in the range of 45 to 50 Btu/lb and a transition temperature of approximately 55 F.

Walking in simulated Martian gravity: influence of the portable life support system's design on dynamic stability.

PubMed

Scott-Pandorf, Melissa M; O'Connor, Daniel P; Layne, Charles S; Josić, Kresimir; Kurz, Max J

2009-09-01

With human exploration of the moon and Mars on the horizon, research considerations for space suit redesign have surfaced. The portable life support system (PLSS) used in conjunction with the space suit during the Apollo missions may have influenced the dynamic balance of the gait pattern. This investigation explored potential issues with the PLSS design that may arise during the Mars exploration. A better understanding of how the location of the PLSS load influences the dynamic stability of the gait pattern may provide insight, such that space missions may have more productive missions with a smaller risk of injury and damaging equipment while falling. We explored the influence the PLSS load position had on the dynamic stability of the walking pattern. While walking, participants wore a device built to simulate possible PLSS load configurations. Floquet and Lyapunov analysis techniques were used to quantify the dynamic stability of the gait pattern. The dynamic stability of the gait pattern was influenced by the position of load. PLSS loads that are placed high and forward on the torso resulted in less dynamically stable walking patterns than loads placed evenly and low on the torso. Furthermore, the kinematic results demonstrated that all joints of the lower extremity may be important for adjusting to different load placements and maintaining dynamic stability. Space scientists and engineers may want to consider PLSS designs that distribute loads evenly and low, and space suit designs that will not limit the sagittal plane range of motion at the lower extremity joints.

Magma traps and driving pressure: consequences for pluton shape and emplacement in an extensional regime

NASA Astrophysics Data System (ADS)

Hogan, John P.; Price, Jonathan D.; Gilbert, M. Charles

1998-09-01

The level of emplacement and final form of felsic and mafic igneous rocks of the Wichita Mountains Igneous Province, southwestern Oklahoma, U.S.A. are discussed in light of magma driving pressure, lithostatic load, and crustal magma traps. Deposition of voluminous A-type rhyolites upon an eroded gabbroic substrate formed a subhorizontal strength anisotropy that acted as a crustal magma trap for subsequent rising felsic and mafic magma. Intruded along this crustal magma trap are the A-type sheet granites (length/thickness 100:1) of the Wichita Granite Group, of which the Mount Scott Granite sheet is typical, and smaller plutons of biotite bearing Roosevelt Gabbro. In marked contrast to the subhorizontal granite sheets, the gabbro plutons form more equant stocks with flat roofs and steep side walls. Late Diabase dikes cross-cut all other units, but accompanying basaltic flows are extremely rare in the volcanic pile. Based on magmastatic calculations, we draw the following conclusions concerning the level of emplacement and the shape of these intrusions. (1) Magma can rise to a depth at which the magma driving pressure becomes negligible. Magma that maintains a positive driving pressure at the surface has the potential to erupt. (2) Magma ascent may be arrested at a deeper level in the crust by a subhorizontal strength anisotropy (i.e. crustal magma trap) if the magma driving pressure is greater than or equal to the lithostatic load at the depth of the subhorizontal strength anisotropy. (3) Subhorizontal sheet-intrusions form along crustal magma traps when the magma driving pressure greatly exceeds the lithostatic load. Under such conditions, the magma driving pressure is sufficent to lift the overburden to create the necessary space for the intrusion. (4) Thicker steep-sided stocks or batholiths, with flat roofs, form at crustal magma traps when the magma driving pressure approximates that of the lithostatic load. Under these conditions, the necessary space for the intrusion must be created by other mechanisms (e.g. stoping). (5) Subvertical sheets (i.e. dikes) form when the magma driving pressure is less than the lithostatic load at the level of emplacement.

A Flexible Method for Producing F.E.M. Analysis of Bone Using Open-Source Software

NASA Technical Reports Server (NTRS)

Boppana, Abhishektha; Sefcik, Ryan; Myers, Jerry G.; Lewandowski, Beth

2016-01-01

Individuals who experience decreases in load-bearing bone densities can be subject to a higher risk of bone fracture during daily activity. Astronauts may lose up to nine percent of their load-bearing bone density for every month they spend in space [1]. Because of this, specialized countermeasures reduce percent loss in bone density and reduce fracture risk upon returning to Earth. Astronauts will typically not be at risk for fracture during spaceflight, because of the lesser loads experienced in microgravity conditions. However, once back on Earth, astronauts have an increased risk for bone fracture as a result of weakened bone and return to 1G conditions [2]. It is therefore important to understand the significance of any bone density loss in addition to developing exercises in an attempt to limit losses in bone strength. NASA seeks to develop a deeper understanding of fracture risk through the development of a computational bone strength model to assess the bone fracture risk of astronauts pre-flight and post-flight. This study addresses the several key processes needed to develop such strength analyses using medical image processing and finite element modeling.

Combined loading criterial influence on structural performance

NASA Technical Reports Server (NTRS)

Kuchta, B. J.; Sealey, D. M.; Howell, L. J.

1972-01-01

An investigation was conducted to determine the influence of combined loading criteria on the space shuttle structural performance. The study consisted of four primary phases: Phase (1) The determination of the sensitivity of structural weight to various loading parameters associated with the space shuttle. Phase (2) The determination of the sensitivity of structural weight to various levels of loading parameter variability and probability. Phase (3) The determination of shuttle mission loading parameters variability and probability as a function of design evolution and the identification of those loading parameters where inadequate data exists. Phase (4) The determination of rational methods of combining both deterministic time varying and probabilistic loading parameters to provide realistic design criteria. The study results are presented.

14 CFR 133.17 - Requirements for issuance of a rotorcraft external-load operator certificate.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Requirements for issuance of a rotorcraft external-load operator certificate. 133.17 Section 133.17 Aeronautics and Space FEDERAL AVIATION... §§ 133.19, 133.21, and 133.23, the Administrator issues a Rotorcraft External-Load Operator Certificate...

14 CFR 133.17 - Requirements for issuance of a rotorcraft external-load operator certificate.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Requirements for issuance of a rotorcraft external-load operator certificate. 133.17 Section 133.17 Aeronautics and Space FEDERAL AVIATION... §§ 133.19, 133.21, and 133.23, the Administrator issues a Rotorcraft External-Load Operator Certificate...

Parachute Swivel Mechanism for planetary entry

NASA Technical Reports Server (NTRS)

Birner, R.; Kaese, J.; Koller, F.; Muehlner, E.; Luhmann, H.-J.

1993-01-01

A parachute swivel mechanism (PSM) for planetary entry missions such as a Mars probe (MARSNET) or return of cometary material samples (ROSETTA mission) has been developed. The purpose of the PSM is to decouple the spin of the probe from the parachute, with low friction torque, during both the deployment and descent phases. Critical requirements are high shock loads, low friction, low temperatures, and several years of storage in the deep space environment (during the cruise phase of the probe, prior to operation). The design uses a main thrust ball bearing to cope with the load requirement and a smaller thrust ball bearing for guiding of the shaft. Except for use on the Viking and Galileo swivels, it appears that this type of bearing has very rarely been employed in space mechanisms, so that little is known of its friction behavior with dry lubrication. A slip ring assembly allows the transfer of electrical power for post-reefing of the parachute. A test program has been conducted covering the environmental conditions of Mars entry and Earth reentry. This paper describes requirement constraints, model missions of planetary entries, a bearing trade-off, analyses performed, design details, the lubrication system, and test results (friction torque versus load/spin rate). In addition, the design of the test rig is addressed.

Monitoring of Microbial Loads During Long Duration Missions as a Risk Reduction Tool

NASA Astrophysics Data System (ADS)

Roman, M. C.; Mena, K. D.

2012-01-01

Humans have been exploring space for more than 40 years. For all those years, microorganisms have accompanied both un-manned spacecraft/cargo and manned vessels. Microorganisms are everywhere on Earth, could easily adapt to new environments, and/or can rapidly mutate to survive in very harsh conditions. Their presence in spacecraft and cargo have caused a few inconveniences over the years of human spaceflight, ranging from crew health, life support systems challenges, and material degradation. The sterilization of spacecraft that will host humans in long duration mission would be a costly operation that will not provide a long-term solution to the microbial colonization of the vessels. As soon as a human is exposed to the spacecraft, microorganisms start populating the new environment during the mission. As the human presence in space increases in length, the risk from the microbial load to hardware and crew will also increase. Mitigation of this risk involves several different strategies that will include minimizing the microbial load (in numbers and diversity) and monitoring. This paper will provide a list of the risk mitigation strategies that should be implemented during ground processing, and during the mission. It will also discuss the areas that should be reviewed before an effective in-flight microbial monitoring regimen is implemented.

Fluid/electrolyte and endocrine changes in space flight

NASA Technical Reports Server (NTRS)

Huntoon, Carolyn Leach

1989-01-01

The primary effects of space flight that influence the endocrine system and fluid and electrolyte regulation are the reduction of hydrostatic gradients, reduction in use and gravitational loading of bone and muscle, and stress. Each of these sets into motion a series of responses that culminates in alteration of some homeostatic set points for the environment of space. Set point alterations are believed to include decreases in venous pressure; red blood cell mass; total body water; plasma volume; and serum sodium, chloride, potassium, and osmolality. Serum calcium and phosphate increase. Hormones such as erythropoietin, atrial natriuretic peptide, aldosterone, cortisol, antidiuretic hormone, and growth hormone are involved in the dynamic processes that bring about the new set points. The inappropriateness of microgravity set points for 1-G conditions contributes to astronaut postflight responses.

Dynamic Failure of Integrated Durable Hot Structure for Space Access Vehicles

DTIC Science & Technology

2009-08-01

in nonho- mogeneous solids, which is of the more practical importance, by assuming plane strain conditions. Later on Delale and Erdogan [11], Eischen...12] and Erdogan et al. [13] solved crack problems for non-homogeneous materials under quasi-static loading. With the introduction of FGMs, research on...fracture mechanics of nonhomo- geneous solids gained additional impetus. Jin and Noda [14], Konda and Erdo- gan [15] and Erdogan [16] obtained the

Design of Structurally Efficient Tapered Struts

NASA Technical Reports Server (NTRS)

Messinger, Ross

2010-01-01

This report describes the analytical study of two full-scale tapered composite struts. The analytical study resulted in the design of two structurally efficient carbon/epoxy struts in accordance with NASA-specified geometries and loading conditions. Detailed stress analysis was performed of the insert, end fitting, and strut body to obtain an optimized weight with positive margins. Two demonstration struts were fabricated based on a well-established design from a previous Space Shuttle strut development program.

Motion state analysis of space target based on optical cross section

NASA Astrophysics Data System (ADS)

Tian, Qichen; Li, Zhi; Xu, Can; Liu, Chenghao

2017-10-01

In order to solve the problem that the movement state analysis method of the space target based on OCS is not related to the real motion state. This paper proposes a method based on OCS for analyzing the state of space target motion. This paper first establish a three-dimensional model of real STSS satellite, then change the satellite's surface into element, and assign material to each panel according to the actual conditions of the satellite. This paper set up a motion scene according to the orbit parameters of STSS satellite in STK, and the motion states are set to three axis steady state and slowly rotating unstable state respectively. In these two states, the occlusion condition of the surface element is firstly determined, and the effective face element is selected. Then, the coordinates of the observation station and the solar coordinates in the satellite body coordinate system are input into the OCS calculation program, and the OCS variation curves of the three axis steady state and the slow rotating unstable state STSS satellite are obtained. Combining the satellite surface structure and the load situation, the OCS change curve of the three axis stabilized satellite is analyzed, and the conclude that the OCS curve fluctuates up and down when the sunlight is irradiated to the load area; By using Spectral analysis method, autocorrelation analysis and the cross residual method, the rotation speed of OCS satellite in slow rotating unstable state is analyzed, and the rotation speed of satellite is successfully reversed. By comparing the three methods, it is found that the cross residual method is more accurate.

SSME/side loads analysis for flight configuration, revision A. [structural analysis of space shuttle main engine under side load excitation

NASA Technical Reports Server (NTRS)

Holland, W.

1974-01-01

This document describes the dynamic loads analysis accomplished for the Space Shuttle Main Engine (SSME) considering the side load excitation associated with transient flow separation on the engine bell during ground ignition. The results contained herein pertain only to the flight configuration. A Monte Carlo procedure was employed to select the input variables describing the side load excitation and the loads were statistically combined. This revision includes an active thrust vector control system representation and updated orbiter thrust structure stiffness characteristics. No future revisions are planned but may be necessary as system definition and input parameters change.

Performance analysis of radiation cooled dc transmission lines for high power space systems

NASA Technical Reports Server (NTRS)

Schwarze, G. E.

1985-01-01

As space power levels increase to meet mission objectives and also as the transmission distance between power source and load increases, the mass, volume, power loss, and operating voltage and temperature become important system design considerations. This analysis develops the dependence of the specific mass and percent power loss on hte power and voltage levels, transmission distance, operating temperature and conductor material properties. Only radiation cooling is considered since the transmission line is assumed to operate in a space environment. The results show that the limiting conditions for achieving low specific mass, percent power loss, and volume for a space-type dc transmission line are the permissible transmission voltage and operating temperature. Other means to achieve low specific mass include the judicious choice of conductor materials. The results of this analysis should be immediately applicable to power system trade-off studies including comparisons with ac transmission systems.

Evaluation of ADCP apparent bed load velocity in a large sand-bed river: Moving versus stationary boat conditions

USGS Publications Warehouse

Jamieson, E.C.; Rennie, C.D.; Jacobson, R.B.; Townsend, R.D.

2011-01-01

Detailed mapping of bathymetry and apparent bed load velocity using a boat-mounted acoustic Doppler current profiler (ADCP) was carried out along a 388-m section of the lower Missouri River near Columbia, Missouri. Sampling transects (moving boat) were completed at 5- and 20-m spacing along the study section. Stationary (fixed-boat) measurements were made by maintaining constant boat position over a target point where the position of the boat did not deviate more than 3 m in any direction. For each transect and stationary measurement, apparent bed load velocity (vb) was estimated using ADCP bottom tracking data and high precision real-time kinematic (RTK) global positioning system (GPS). The principal objectives of this research are to (1) determine whether boat motion introduces a bias in apparent bed load velocity measurements; and (2) evaluate the reliability of ADCP bed velocity measurements for a range of sediment transport environments. Results indicate that both high transport (vb>0.6 m/s) and moving-boat conditions (for both high and low transport environments) increase the relative variability in estimates of mean bed velocity. Despite this, the spatially dense single-transect measurements were capable of producing detailed bed velocity maps that correspond closely with the expected pattern of sediment transport over large dunes. ?? 2011 American Society of Civil Engineers.

Design and Control of Hydronic Radiant Cooling Systems

NASA Astrophysics Data System (ADS)

Feng, Jingjuan

Improving energy efficiency in the Heating Ventilation and Air conditioning (HVAC) systems in buildings is critical to achieve the energy reduction in the building sector, which consumes 41% of all primary energy produced in the United States, and was responsible for nearly half of U.S. CO2 emissions. Based on a report by the New Building Institute (NBI), when HVAC systems are used, about half of the zero net energy (ZNE) buildings report using a radiant cooling/heating system, often in conjunction with ground source heat pumps. Radiant systems differ from air systems in the main heat transfer mechanism used to remove heat from a space, and in their control characteristics when responding to changes in control signals and room thermal conditions. This dissertation investigates three related design and control topics: cooling load calculations, cooling capacity estimation, and control for the heavyweight radiant systems. These three issues are fundamental to the development of accurate design/modeling tools, relevant performance testing methods, and ultimately the realization of the potential energy benefits of radiant systems. Cooling load calculations are a crucial step in designing any HVAC system. In the current standards, cooling load is defined and calculated independent of HVAC system type. In this dissertation, I present research evidence that sensible zone cooling loads for radiant systems are different from cooling loads for traditional air systems. Energy simulations, in EnergyPlus, and laboratory experiments were conducted to investigate the heat transfer dynamics in spaces conditioned by radiant and air systems. The results show that the magnitude of the cooling load difference between the two systems ranges from 7-85%, and radiant systems remove heat faster than air systems. For the experimental tested conditions, 75-82% of total heat gain was removed by radiant system during the period when the heater (simulating the heat gain) was on, while for air system, 61-63% were removed. From a heat transfer perspective, the differences are mainly because the chilled surfaces directly remove part of the radiant heat gains from a zone, thereby bypassing the time-delay effect caused by the interaction of radiant heat gain with non-active thermal mass in air systems. The major conclusions based on these findings are: 1) there are important limitations in the definition of cooling load for a mixing air system described in Chapter 18 of ASHRAE Handbook of Fundamentals when applied to radiant systems; 2) due to the obvious mismatch between how radiant heat transfer is handled in traditional cooling load calculation methods compared to its central role in radiant cooling systems, this dissertation provides improvements for the current cooling load calculation method based on the Heat Balance procedure. The Radiant Time Series method is not appropriate for radiant system applications. The findings also directly apply to the selection of space heat transfer modeling algorithms that are part of all energy modeling software. Cooling capacity estimation is another critical step in a design project. The above mentioned findings and a review of the existing methods indicates that current radiant system cooling capacity estimation methods fail to take into account incident shortwave radiation generated by solar and lighting in the calculation process. This causes a significant underestimation (up to 150% for some instances) of floor cooling capacity when solar load is dominant. Building performance simulations were conducted to verify this hypothesis and quantify the impacts of solar for different design scenarios. A new simplified method was proposed to improve the predictability of the method described in ISO 11855 when solar radiation is present. The dissertation also compares the energy and comfort benefits of the model-based predictive control (MPC) method with a fine-tuned heuristic control method when applied to a heavyweight embedded surface system. A first order dynamic model of a radiant slab system was developed for implementation in model predictive controllers. A calibrated EnergyPlus model of a typical office building in California was used as a testbed for the comparison. The results indicated that MPC is able to reduce the cooling tower energy consumption by 55% and pumping power consumption by 26%, while maintaining equivalent or even better thermal comfort conditions. In summary, the dissertation work has: (1) provided clear evidence that the fundamental heat transfer mechanisms differ between radiant and air systems. These findings have important implications for the development of accurate and reliable design and energy simulation tools; (2) developed practical design methods and guidance to aid practicing engineers who are designing radiant systems; and (3) outlined future research and design tools need to advance the state-of-knowledge and design and operating guidelines for radiant systems.

Recommendations for a wind profiling network to support Space Shuttle launches

NASA Technical Reports Server (NTRS)

Zamora, R. J.

1992-01-01

The feasibility is examined of a network of clear air radar wind profilers to forecast wind conditions before Space Shuttle launches during winter. Currently, winds are measured only in the vicinity of the shuttle launch site and wind loads on the launch vehicle are estimated using these measurements. Wind conditions upstream of the Cape are not monitored. Since large changes in the wind shear profile can be associated with weather systems moving over the Cape, it may be possible to improve wind forecasts over the launch site if wind measurements are made upstream. A radar wind profiling system is in use at the Space Shuttle launch site. This system can monitor the wind profile continuously. The existing profiler could be combined with a number of radars located upstream of the launch site. Thus, continuous wind measurements would be available upstream and at the Cape. NASA-Marshall representatives have set the requirements for radar wind profiling network. The minimum vertical resolution of the network must be set so that the wind shears over the depths greater than or = 1 km will be detected. The network should allow scientists and engineers to predict the wind profile over the Cape 6 hours before a Space Shuttle launch.

Simulated space radiation sensitizes bone but not muscle to the catabolic effects of mechanical unloading.

PubMed

Krause, Andrew R; Speacht, Toni L; Zhang, Yue; Lang, Charles H; Donahue, Henry J

2017-01-01

Deep space travel exposes astronauts to extended periods of space radiation and mechanical unloading, both of which may induce significant muscle and bone loss. Astronauts are exposed to space radiation from solar particle events (SPE) and background radiation referred to as galactic cosmic radiation (GCR). To explore interactions between skeletal muscle and bone under these conditions, we hypothesized that decreased mechanical load, as in the microgravity of space, would lead to increased susceptibility to space radiation-induced bone and muscle loss. We evaluated changes in bone and muscle of mice exposed to hind limb suspension (HLS) unloading alone or in addition to proton and high (H) atomic number (Z) and energy (E) (HZE) (16O) radiation. Adult male C57Bl/6J mice were randomly assigned to six groups: No radiation ± HLS, 50 cGy proton radiation ± HLS, and 50 cGy proton radiation + 10 cGy 16O radiation ± HLS. Radiation alone did not induce bone or muscle loss, whereas HLS alone resulted in both bone and muscle loss. Absolute trabecular and cortical bone volume fraction (BV/TV) was decreased 24% and 6% in HLS-no radiation vs the normally loaded no-radiation group. Trabecular thickness and mineral density also decreased with HLS. For some outcomes, such as BV/TV, trabecular number and tissue mineral density, additional bone loss was observed in the HLS+proton+HZE radiation group compared to HLS alone. In contrast, whereas HLS alone decreased muscle mass (19% gastrocnemius, 35% quadriceps), protein synthesis, and increased proteasome activity, radiation did not exacerbate these catabolic outcomes. Our results suggest that combining simulated space radiation with HLS results in additional bone loss that may not be experienced by muscle.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herk, Anastasia; Poerschke, Andrew

The New York State Energy Research and Development Authority (NYSERDA) is interested in finding cost-effective solutions for deep energy retrofits (DERs) related to exterior wall insulation in a cold climate, with targets of 50% peak load reduction and 50% space conditioning energy savings. The U.S. Department of Energy Building America team, IBACOS, in collaboration with GreenHomes America, Inc. (GHA), was contracted by NYSERDA to research exterior wall insulation solutions. In addition to exterior wall insulation, the strategies included energy upgrades where needed in the attic, mechanical and ventilation systems, basement, band joist, walls, and floors. Under Building America, IBACOS ismore » studying the impact of a “thermal enclosure” DER on the sizing of the space conditioning system and the occupant comfort if the thermal capacity of the heating and cooling system is dramatically downsized without any change in the existing heating and cooling distribution system (e.g., size, tightness and supply outlet configurations).« less

Aeroelastic Response and Protection of Space Shuttle External Tank Cable Trays

NASA Technical Reports Server (NTRS)

Edwards, John W.; Keller, Donald F.; Schuster, David M.; Piatak, David J.; Rausch, Russ D.; Bartels, Robert E.; Ivanco, Thomas G.; Cole, Stanley R.; Spain, Charles V.

2005-01-01

Sections of the Space Shuttle External Tank Liquid Oxygen (LO2) and Liquid Hydrogen (LH2) cable trays are shielded from potentially damaging airloads with foam Protuberance Aerodynamic Load (PAL) Ramps. Flight standard design LO2 and LH2 cable tray sections were tested with and without PAL Ramp models in the United States Air Force Arnold Engineering Development Center s (AEDC) 16T transonic wind tunnel to obtain experimental data on the aeroelastic stability and response characteristics of the trays and as part of the larger effort to determine whether the PAL ramps can be safely modified or removed. Computational Fluid Dynamic simulations of the full-stack shuttle launch configuration were used to investigate the flow characeristics around and under the cable trays without the protective PAL ramps and to define maximum crossflow Mach numbers and dynamic pressures experienced during launch. These crossflow conditions were used to establish wind tunnel test conditions which also included conservative margins. For all of the conditions and configurations tested, no aeroelastic instabilities or unacceptable dynamic response levels were encountered and no visible structural damage was experienced by any of the tested cable tray sections. Based upon this aeroelastic characterization test, three potentially acceptable alternatives are available for the LO2 cable tray PAL Ramps: Mini-Ramps, Tray Fences, or No Ramps. All configurations were tested to maximum conditions, except the LH2 trays at -15 deg. crossflow angle. This exception is the only caveat preventing the proposal of acceptable alternative configurations for the LH2 trays as well. Structural assessment of all tray loads and tray response measurements from launches following the Shuttle Return To Flight with the existing PAL Ramps will determine the acceptability of these PAL Ramp alternatives.

Rayleigh wave effects in an elastic half-space.

NASA Technical Reports Server (NTRS)

Aggarwal, H. R.

1972-01-01

Consideration of Rayleigh wave effects in a homogeneous isotropic linearly elastic half-space subject to an impulsive uniform disk pressure loading. An approximate formula is obtained for the Rayleigh wave effects. It is shown that the Rayleigh waves near the center of loading arise from the portion of the dilatational and shear waves moving toward the axis, after they originate at the edge of the load disk. A study is made of the vertical displacement due to Rayleigh waves at points on the axis near the surface of the elastic half-space.

Exergy Analysis of a Two-Stage Ground Source Heat Pump with a Vertical Bore for Residential Space Conditioning under Simulated Occupancy

DOE PAGES

Ally, Moonis Raza; Munk, Jeffrey D.; Baxter, Van D.; ...

2015-06-26

This twelve-month field study analyzes the performance of a 7.56W (2.16- ton) water-to-air-ground source heat pump (WA-GSHP) to satisfy domestic space conditioning loads in a 253 m 2 house in a mixed-humid climate in the United States. The practical feasibility of using the ground as a source of renewable energy is clearly demonstrated. Better than 75% of the energy needed for space heating was extracted from the ground. The average monthly electricity consumption for space conditioning was only 40 kWh at summer and winter thermostat set points of 24.4°C and 21.7°C, respectively. The WA-GSHP shared the same 94.5 m verticalmore » bore ground loop with a separate water-to-water ground-source heat pump (WW-GSHP) for meeting domestic hot water needs in the same house. Sources of systemic irreversibility, the main cause of lost work are identified using Exergy and energy analysis. Quantifying the sources of Exergy and energy losses is essential for further systemic improvements. The research findings suggest that the WA-GSHPs are a practical and viable technology to reduce primary energy consumption and greenhouse gas emissions under the IECC 2012 Standard, as well as the European Union (EU) 2020 targets of using renewable energy resources.« less

The influence of pore-fluid in the soil on ground vibrations from a tunnel embedded in a layered half-space

NASA Astrophysics Data System (ADS)

Yuan, Zonghao; Cao, Zhigang; Boström, Anders; Cai, Yuanqiang

2018-04-01

A computationally efficient semi-analytical solution for ground-borne vibrations from underground railways is proposed and used to investigate the influence of hydraulic boundary conditions at the scattering surfaces and the moving ground water table on ground vibrations. The arrangement of a dry soil layer with varying thickness resting on a saturated poroelastic half-space, which includes a circular tunnel subject to a harmonic load at the tunnel invert, creates the scenario of a moving water table for research purposes in this paper. The tunnel is modelled as a hollow cylinder, which is made of viscoelastic material and buried in the half-space below the ground water table. The wave field in the dry soil layer consists of up-going and down-going waves while the wave field in the tunnel wall consists of outgoing and regular cylindrical waves. The complete solution for the saturated half-space with a cylindrical hole is composed of down-going plane waves and outgoing cylindrical waves. By adopting traction-free boundary conditions on the ground surface and continuity conditions at the interfaces of the two soil layers and of the tunnel and the surrounding soil, a set of algebraic equations can be obtained and solved in the transformed domain. Numerical results show that the moving ground water table can cause an uncertainty of up to 20 dB for surface vibrations.

Standard versus physiologic bone preparation in total knee arthroplasty and the effect on joint space opening.

PubMed

Burkhart, Timothy A; Herman, Benjamin V; Perry, Kevin; Vandekerckhove, Pieter-Jan; Howard, James; Lanting, Brent

2017-11-01

Total knee arthroplasty is an effective treatment for osteoarthritis. Restoration of physiologic varus alignment may restore the native soft tissue tension and improve outcomes. Six paired fresh-frozen knee specimens were used to perform total knee arthroplastys. The left and right sides of were randomly assigned to have either a physiologic alignment cut or a standard of care neutral alignment bony cut prior to the implantation. Loads of 100 and 200N were applied at 0, 30, 60, and 90° of flexion and the magnitude of the medial and lateral compartment distraction was measured. The loads were applied with the knee specimen intact and post arthroplasty. The physiologic alignment had no difference between medial and lateral gaps at either load. With 100N of load the physiologic alignment had a greater gap at 90° than at full extension while the standard alignment had significantly more gap at 60° of flexion than full extension. The physiologic alignment had a significantly greater gap with the implant compared to the intact condition at both loads. The standard alignment had no significant difference in overall gap between the implant and intact condition with any load. Although performing a physiologic aligned TKA resulted in medial-lateral soft tissue balance, the flexion gap was found to have greater magnitude than the intact knee. Notably, a neutral aligned TKA was found to be balanced, but also was found to recreate the intact knee flexion gaps. These results suggest that coronal plane stability can be achieved with physiologic alignment objectives, but the clinician needs to be aware of the potential to have greater laxity than the intact and neutral alignment surgical objectives. Copyright © 2017 Elsevier Ltd. All rights reserved.

Skylight energy performance and design optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arasteh, D.; Johnson, R.; Selkowitz, S.

1984-02-01

Proper skylight utilization can significantly lower energy requirements and peak electrical loads for space conditioning and lighting in commercial buildings. In this study we systematically explore the energy effects of skylight systems in a prototypical office building and examine the savings from daylighting. The DOE-2.1B energy analysis computer program with its newly incorporated daylighting algorithms was used to generate more than 2000 parametric simulations for seven US climates. The parameters varied include skylight-to-roof ratio, shading coefficient, visible transmittance, skylight well light loss, electric lighting power density, roof heat transfer coefficient, and type of electric lighting control. For specific climates wemore » identify roof/skylight characteristics that minimize total energy or peak electrical load requirements.« less

Simulations of X-ray diffraction of shock-compressed single-crystal tantalum with synchrotron undulator sources.

PubMed

Tang, M X; Zhang, Y Y; E, J C; Luo, S N

2018-05-01

Polychromatic synchrotron undulator X-ray sources are useful for ultrafast single-crystal diffraction under shock compression. Here, simulations of X-ray diffraction of shock-compressed single-crystal tantalum with realistic undulator sources are reported, based on large-scale molecular dynamics simulations. Purely elastic deformation, elastic-plastic two-wave structure, and severe plastic deformation under different impact velocities are explored, as well as an edge release case. Transmission-mode diffraction simulations consider crystallographic orientation, loading direction, incident beam direction, X-ray spectrum bandwidth and realistic detector size. Diffraction patterns and reciprocal space nodes are obtained from atomic configurations for different loading (elastic and plastic) and detection conditions, and interpretation of the diffraction patterns is discussed.

Simulations of X-ray diffraction of shock-compressed single-crystal tantalum with synchrotron undulator sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, M. X.; Zhang, Y. Y.; E, J. C.

Polychromatic synchrotron undulator X-ray sources are useful for ultrafast single-crystal diffraction under shock compression. Here, simulations of X-ray diffraction of shock-compressed single-crystal tantalum with realistic undulator sources are reported, based on large-scale molecular dynamics simulations. Purely elastic deformation, elastic–plastic two-wave structure, and severe plastic deformation under different impact velocities are explored, as well as an edge release case. Transmission-mode diffraction simulations consider crystallographic orientation, loading direction, incident beam direction, X-ray spectrum bandwidth and realistic detector size. Diffraction patterns and reciprocal space nodes are obtained from atomic configurations for different loading (elastic and plastic) and detection conditions, and interpretation of themore » diffraction patterns is discussed.« less

Poromicromechanics reveals that physiological bone strains induce osteocyte-stimulating lacunar pressure.

PubMed

Scheiner, Stefan; Pivonka, Peter; Hellmich, Christian

2016-02-01

Mechanical loads which are macroscopically acting onto bony organs, are known to influence the activities of biological cells located in the pore spaces of bone, in particular so the signaling and production processes mediated by osteocytes. The exact mechanisms by which osteocytes are actually able to "feel" the mechanical loading and changes thereof, has been the subject of numerous studies, and, while several hypotheses have been brought forth over time, this topic has remained a matter of debate. Relaxation times reported in a recent experimental study of Gardinier et al. (Bone 46(4):1075-1081, 2010) strongly suggest that the lacunar pores are likely to experience, during typical physiological load cycles, not only fluid transport, but also undrained conditions. The latter entail the buildup of lacunar pore pressures, which we here quantify by means of a thorough multiscale modeling approach. In particular, the proposed model is based on classical poroelasticity theory, and able to account for multiple pore spaces. First, the model reveals distinct nonlinear dependencies of the resulting lacunar (and vascular) pore pressures on the underlying bone composition, highlighting the importance of a rigorous multiscale approach for appropriate computation of the aforementioned pore pressures. Then, the derived equations are evaluated for macroscopic (uniaxial as well as hydrostatic) mechanical loading of physiological magnitude. The resulting model-predicted pore pressures agree very well with the pressures that have been revealed, by means of in vitro studies, to be of adequate magnitude for modulating the responses of biological cells, including osteocytes. This underlines that osteocytes may respond to many types of loading stimuli at the same time, in particular so to fluid flow and hydrostatic pressure.

Interaction between a railway track and uniformly moving tandem wheels

NASA Astrophysics Data System (ADS)

Belotserkovskiy, P. M.

2006-12-01

Interaction among loaded wheels via railway track is studied. The vertical parametric oscillations of an infinite row of identical equally spaced wheels, bearing constant load and uniformly moving over a railway track, are calculated by means of Fourier series technique. If the distance between two consecutive wheels is big enough, then one can disregard their interaction via the railway track and consider every wheel as a single one. In this case, however, the Fourier series technique represents an appropriate computation time-saving approximation to a Fourier integral transformation technique that describes the oscillations of a single moving wheel. Two schemes are considered. In the first scheme, every wheel bears the same load. In the second one, consecutive wheels bear contrarily directed loads of the same magnitude. The second scheme leads to simpler calculations and so is recommended to model the wheel-track interaction. The railway track periodicity due to sleeper spacing is taken into account. Each period is the track segment between two adjacent sleepers. A partial differential equation with constant coefficients governs the vertical oscillations of each segment. Boundary conditions bind the oscillations of two neighbour segments and provide periodicity to the track. The shear deformation in the rail cross-section strongly influences the parametric oscillations. It also causes discontinuity of the rail centre-line slope at any point, where a concentrated transverse force is applied. Therefore, Timoshenko beam properties with respect to the topic of this paper are discussed. Interaction between a railway track and a bogie moving at moderate speed is studied. The study points to influence of the bogie frame oscillations on variation in the wheel-rail contact force over the sleeper span. The simplified bogie model considered includes only the primary suspension. A static load applied to the bogie frame centre presents the vehicle body.

LSRA STS Tire Test - on rim

NASA Technical Reports Server (NTRS)

1995-01-01

From 1993 to 1995, in conjunction with other NASA centers, NASA Dryden Flight Research Center, Edwards, California, used a Convair CV-990 airplane as a Landing Systems Research Aircraft (LSRA) to perform Space Shuttle tire tests. The results provided the Space Shuttle Program with data to support its flight rules and enabled it to resurface a grooved runway at Kennedy Space Center that had added unnecessary wear to the Space Shuttle tires. Tests were done using a unique fixture mounted in the center of the CV-990 fuselage, between the main landing gear. Landing gear systems from other aircraft could be attached to the test fixture, which lowered them to the runway surface during actual landings. The LSRA had the ability to reproduce the loads and speeds of the other aircraft, as well as simulate crosswind landing conditions in a safe, controlled environment. The video clip shows a landing on the concrete runway at Edwards, California on August 11, 1995, which concluded the Space Shuttle gear research program. As the Space Shuttle tire was lowered onto the surface, it was destroyed almost instantly. The rim scraped on the concrete, and stopped rolling as it became flat. It heated up and left a flaming trail of hot rubber and aluminum alloy particles. Notice how the fire quickly went out as the test gear was raised, indicating a safer condition than prevailed in a lakebed landing.

Space station common module thermal management: Design and construction of a test bed

NASA Technical Reports Server (NTRS)

Barile, R. G.

1986-01-01

In this project, a thermal test bed was designed, simulated, and planned for construction. The thermal system features interior and exterior thermal loads and interfacing with the central-radiator thermal bus. Components of the test bed include body mounted radiator loop with interface heat exchangers (600 Btu/hr); an internal loop with cabin air-conditioning and cold plates (3400 Btu/hr); interface heat exchangers to the central bus (13,000 Btu/hr); and provisions for new technology including advanced radiators, thermal storage, and refrigeration. The apparatus will be mounted in a chamber, heated with lamps, and tested in a vacuum chamber with LN2-cooled walls. Simulation of the test bed was accomplished using a DEC PRO 350 computer and the software package TK! olver. Key input variables were absorbed solar radiation and cold plate loads. The results indicate temperatures on the two loops will be nominal when the radiation and cold plate loads are in the range of 25% to 75% of peak loads. If all loads fall to zero, except the cabin air system which was fixed, the radiator fluid will drop below -100 F and may cause excessive pressure drop. If all loads reach 100%, the cabin air temperature could rise to 96 F.

Model Development and Experimental Validation of the Fusible Heat Sink Design for Exploration Vehicles

NASA Technical Reports Server (NTRS)

Cognata, Thomas J.; Leimkuehler, Thomas O.; Sheth, Rubik B.; Le,Hung

2012-01-01

The Fusible Heat Sink is a novel vehicle heat rejection technology which combines a flow through radiator with a phase change material. The combined technologies create a multi-function device able to shield crew members against Solar Particle Events (SPE), reduce radiator extent by permitting sizing to the average vehicle heat load rather than to the peak vehicle heat load, and to substantially absorb heat load excursions from the average while constantly maintaining thermal control system setpoints. This multi-function technology provides great flexibility for mission planning, making it possible to operate a vehicle in hot or cold environments and under high or low heat load conditions for extended periods of time. This paper describes the model development and experimental validation of the Fusible Heat Sink technology. The model developed was intended to meet the radiation and heat rejection requirements of a nominal MMSEV mission. Development parameters and results, including sizing and model performance will be discussed. From this flight-sized model, a scaled test-article design was modeled, designed, and fabricated for experimental validation of the technology at Johnson Space Center thermal vacuum chamber facilities. Testing showed performance comparable to the model at nominal loads and the capability to maintain heat loads substantially greater than nominal for extended periods of time.

Model Development and Experimental Validation of the Fusible Heat Sink Design for Exploration Vehicles

NASA Technical Reports Server (NTRS)

Cognata, Thomas J.; Leimkuehler, Thomas; Sheth, Rubik; Le, Hung

2013-01-01

The Fusible Heat Sink is a novel vehicle heat rejection technology which combines a flow through radiator with a phase change material. The combined technologies create a multi-function device able to shield crew members against Solar Particle Events (SPE), reduce radiator extent by permitting sizing to the average vehicle heat load rather than to the peak vehicle heat load, and to substantially absorb heat load excursions from the average while constantly maintaining thermal control system setpoints. This multi-function technology provides great flexibility for mission planning, making it possible to operate a vehicle in hot or cold environments and under high or low heat load conditions for extended periods of time. This paper describes the modeling and experimental validation of the Fusible Heat Sink technology. The model developed was intended to meet the radiation and heat rejection requirements of a nominal MMSEV mission. Development parameters and results, including sizing and model performance will be discussed. From this flight-sized model, a scaled test-article design was modeled, designed, and fabricated for experimental validation of the technology at Johnson Space Center thermal vacuum chamber facilities. Testing showed performance comparable to the model at nominal loads and the capability to maintain heat loads substantially greater than nominal for extended periods of time.

Gear Tooth Root Stresses of a Very Heavily Loaded Gear Pair-Case Study: Orbiter Body Flap Actuator Pinion and Ring Gear

NASA Technical Reports Server (NTRS)

Krantz, Timothy L.; Handschuh, Robert F.

2015-01-01

The space shuttle orbiter's body flap actuator gearing was assessed as a case study of the stresses for very heavily loaded external-internal gear pairs (meshing pinion and ring gear). For many applications, using the high point of single tooth contact (HPSTC) to locate the position of the tooth force is adequate for assessing the maximum tooth root stress condition. But for aerospace gearing such an approach may be inadequate for assessing the stress condition while also simultaneously minimizing mass. In this work specialized contact analyses and finite element methods were used to study gear tooth stresses of body flap actuator gears. The analytical solutions considered the elastic deformations as an inherent part of the solutions. The ratio for the maximum tooth stresses using the HPSTC approach solutions relative to the contact analysis and finite element solutions were 1.40 for the ring gear and 1.28 for the pinion gear.

Cryogenic, high speed, turbopump bearing cooling requirements

NASA Technical Reports Server (NTRS)

Dolan, Fred J.; Gibson, Howard G.; Cannon, James L.; Cody, Joe C.

1988-01-01

Although the Space Shuttle Main Engine (SSME) has repeatedly demonstrated the capability to perform during launch, the High Pressure Oxidizer Turbopump (HPOTP) main shaft bearings have not met their 7.5 hour life requirement. A tester is being employed to provide the capability of subjecting full scale bearings and seals to speeds, loads, propellants, temperatures, and pressures which simulate engine operating conditions. The tester design permits much more elaborate instrumentation and diagnostics than could be accommodated in an SSME turbopump. Tests were made to demonstrate the facilities; and the devices' capabilities, to verify the instruments in its operating environment and to establish a performance baseline for the flight type SSME HPOTP Turbine Bearing design. Bearing performance data from tests are being utilized to generate: (1) a high speed, cryogenic turbopump bearing computer mechanical model, and (2) a much improved, very detailed thermal model to better understand bearing internal operating conditions. Parametric tests were also made to determine the effects of speed, axial loads, coolant flow rate, and surface finish degradation on bearing performance.

Reliability assessment of an OVH HV power line truss transmission tower subjected to seismic loading

NASA Astrophysics Data System (ADS)

Winkelmann, Karol; Jakubowska, Patrycja; Soltysik, Barbara

2017-03-01

The study focuses on the reliability of a transmission tower OS24 ON150 + 10, an element of an OVH HV power line, under seismic loading. In order to describe the seismic force, the real-life recording of the horizontal component of the El Centro earthquake was adopted. The amplitude and the period of this excitation are assumed random, their variation is described by Weibull distribution. The possible space state of the phenomenon is given in the form of a structural response surface (RSM methodology), approximated by an ANOVA table with directional sampling (DS) points. Four design limit states are considered: stress limit criterion for a natural load combination, criterion for an accidental combination (one-sided cable snap), vertical and horizontal translation criteria. According to these cases the HLRF reliability index β is used for structural safety assessment. The RSM approach is well suited for the analysis - it is numerically efficient, not excessively time consuming, indicating a high confidence level. Given the problem conditions, the seismic excitation is shown the sufficient trigger to the loss of load-bearing capacity or stability of the tower.

Forward Skirt Structural Testing on the Space Launch System (SLS) Program

NASA Technical Reports Server (NTRS)

Lohrer, J. D.; Wright, R. D.

2016-01-01

Structural testing was performed to evaluate heritage forward skirts from the Space Shuttle program for use on the NASA Space Launch System (SLS) program. Testing was needed because SLS ascent loads are 35% higher than Space Shuttle loads. Objectives of testing were to determine margins of safety, demonstrate reliability, and validate analytical models. Testing combined with analysis was able to show heritage forward skirts were acceptable to use on the SLS program.

Review of the knowledge of microbial contamination of the Russian manned spacecraft.

PubMed

Novikova, N D

2004-02-01

The 15-year experience of orbital station Mir service demonstrated that specifically modified space vehicle environments allows for the consideration of spaceship habitats as a certain ecological niche of microbial community development and functioning, which was formed from the organisms of different physiological and taxonomical groups. The base unit of the orbital station (OS) Mir was launched on February 20, 1986, and on March 13 the first crew arrived to it. From that moment a unique microbiocenosis started forming in the closed environment of the space station, and vital activity of the microorganisms continued for the next 15 years in a specifically changed environment, in conditions of continuous influence of a set of factors intrinsic to space flight. A total of 234 species of bacteria and fungi were found onboard orbital station Mir, among which microorganisms capable of resident colonization of the environment of space objects as a unique anthropotechnological niche were revealed. In such conditions the evolution of microflora is followed by the rise of medical and technical risks that can affect both sanitary-microbiological conditions of the environment and the safety and reliability characteristics of space equipment. The latter is caused by progressing biological damage to the structural materials. The microbial loading dynamic does not have linearly progressing character, but it is a wavy process of alternation of the microflora activation and stabilization phases; on this background there is a change of the dominating species by quantity and prevalence. The accumulated data is evidence of the necessity of the constant control of the microbial environmental factors to maintain their sanitary and microbiological optimum condition and to prevent the processes of constructional materials biodestruction. Copyright 2004 Springer-Verlag

Composite load spectra for select space propulsion structural components

NASA Technical Reports Server (NTRS)

Newell, J. F.; Kurth, R. E.; Ho, H.

1986-01-01

A multiyear program is performed with the objective to develop generic load models with multiple levels of progressive sophistication to simulate the composite (combined) load spectra that are induced in space propulsion system components, representative of Space Shuttle Main Engines (SSME), such as transfer ducts, turbine blades, and liquid oxygen (LOX) posts. Progress of the first year's effort includes completion of a sufficient portion of each task -- probabilistic models, code development, validation, and an initial operational code. This code has from its inception an expert system philosophy that could be added to throughout the program and in the future. The initial operational code is only applicable to turbine blade type loadings. The probabilistic model included in the operational code has fitting routines for loads that utilize a modified Discrete Probabilistic Distribution termed RASCAL, a barrier crossing method and a Monte Carlo method. An initial load model was developed by Battelle that is currently used for the slowly varying duty cycle type loading. The intent is to use the model and related codes essentially in the current form for all loads that are based on measured or calculated data that have followed a slowly varying profile.

First-principles characterization of potassium intercalation in the hexagonal 2H-MoS2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andersen, Amity; Kathmann, Shawn M.; Lilga, Michael A.

2012-01-12

Periodic density functional theory calculations were performed to study the structural and electronic properties of potassium intercalated into hexagonal MoS{sub 2} (2H-MoS{sub 2}). Metallic potassium (K) atoms are incrementally loaded in the hexagonal sites of the interstitial spaces between MoS2 sheets of the 2H-MoS{sub 2} bulk structure generating 2H-KxMoS2 (0.125 {<=} x {<=} 1.0) structures. To accommodate the potassium atoms, the interstitial spacing c parameter in the 2H-MoS{sub 2} bulk expands from 12.816 {angstrom} in 2H-MoS{sub 2} to 16.086 {angstrom} in 2H-K{sub 0.125}MoS{sub 2}. The second lowest potassium loading concentration (K{sub 0.25}MoS{sub 2}) results in the largest interstitial spacing expansionmore » (to c = 16.726 {angstrom}). Our calculations show that there is a small gradual contraction of the interstitial spacing as the potassium loading increases with c = 14.839 {angstrom} for KMoS{sub 2}. This interstitial contraction is correlated with an in-plane expansion of the MoS{sub 2} sheets, which is in good agreement with experimental X-ray diffraction (XRD) measurements. The electronic analysis shows that potassium readily donates its 4s electron to the conduction band of the 2H-K{sub x}MoS{sub 2}, and is largely ionic in character. As a result of the electron donation, the 2H-K{sub x}MoS{sub 2} system changes from a semiconductor to a more metallic system with increasing potassium intercalation. For loadings 0.25 {<=} x {<=} 0.625, triangular Mo-Mo-Mo moieties are prominent and tend to form rhombitrihexagonal motifs. Intercalation of H{sub 2}O molecules that solvate the K atoms is likely to occur in catalytic conditions. The inclusion of two H{sub 2}O molecules per K atom in the K{sub 0.25}MoS{sub 2} structure shows good agreement with XRD measurements.« less

Transall C-160 Life Extension and Avionics Upgrade Programs

DTIC Science & Technology

2000-04-01

theoretically). In The A/C of the second series differed from the first reality, however, one flight took only an average of series A/C as follows...configuration. The progress of the crack was Usable cargo space 139.9 m3 monitored under operational conditions and with different loads: The German Air Force...progress data. Today, the French C- 160 aircraft are maintaned by AIA/CIT (Atelier Industriel A6ronautique/Cellule Industrielle Transall) in Clermont

Probabilistic structural analysis methods and applications

NASA Technical Reports Server (NTRS)

Cruse, T. A.; Wu, Y.-T.; Dias, B.; Rajagopal, K. R.

1988-01-01

An advanced algorithm for simulating the probabilistic distribution of structural responses due to statistical uncertainties in loads, geometry, material properties, and boundary conditions is reported. The method effectively combines an advanced algorithm for calculating probability levels for multivariate problems (fast probability integration) together with a general-purpose finite-element code for stress, vibration, and buckling analysis. Application is made to a space propulsion system turbine blade for which the geometry and material properties are treated as random variables.

Advances in cryogenic foam insulations.

NASA Technical Reports Server (NTRS)

Lemons, C. R.; Salmassy, O. K.; Watts, C. R.

1971-01-01

Description of a discretely oriented thread-reinforced polyurethane foam thermal insulation system for liquid hydrogen fuel tanks. The 3-D foam and glass liner composite is designed to be adhesively bonded to the inside surface of the tank wall and to be in direct contact with liquid hydrogen. All elements of this insulation composite are capable of sustaining the loads and environmental conditions imposed by testing under simulated Space Shuttle vehicle requirements at temperatures between -423 and +350 F.

Mechanical failure probability of glasses in Earth orbit

NASA Technical Reports Server (NTRS)

Kinser, Donald L.; Wiedlocher, David E.

1992-01-01

Results of five years of earth-orbital exposure on mechanical properties of glasses indicate that radiation effects on mechanical properties of glasses, for the glasses examined, are less than the probable error of measurement. During the 5 year exposure, seven micrometeorite or space debris impacts occurred on the samples examined. These impacts were located in locations which were not subjected to effective mechanical testing, hence limited information on their influence upon mechanical strength was obtained. Combination of these results with micrometeorite and space debris impact frequency obtained by other experiments permits estimates of the failure probability of glasses exposed to mechanical loading under earth-orbit conditions. This probabilistic failure prediction is described and illustrated with examples.

Space shuttle solid rocket booster recovery system definition. Volume 2: SRB water impact Monte Carlo computer program, user's manual

NASA Technical Reports Server (NTRS)

1973-01-01

The HD 220 program was created as part of the space shuttle solid rocket booster recovery system definition. The model was generated to investigate the damage to SRB components under water impact loads. The random nature of environmental parameters, such as ocean waves and wind conditions, necessitates estimation of the relative frequency of occurrence for these parameters. The nondeterministic nature of component strengths also lends itself to probabilistic simulation. The Monte Carlo technique allows the simultaneous perturbation of multiple independent parameters and provides outputs describing the probability distribution functions of the dependent parameters. This allows the user to determine the required statistics for each output parameter.

Space Shuttle Main Engine structural analysis and data reduction/evaluation. Volume 2: High pressure oxidizer turbo-pump turbine end bearing analysis

NASA Technical Reports Server (NTRS)

Sisk, Gregory A.

1989-01-01

The high-pressure oxidizer turbopump (HPOTP) consists of two centrifugal pumps, on a common shaft, that are directly driven by a hot-gas turbine. Pump shaft axial thrust is balanced in that the double-entry main inducer/impeller is inherently balanced and the thrusts of the preburner pump and turbine are nearly equal but opposite. Residual shaft thrust is controlled by a self-compensating, non-rubbing, balance piston. Shaft hang-up must be avoided if the balance piston is to perform properly. One potential cause of shaft hang-up is contact between the Phase 2 bearing support and axial spring cartridge of the HPOTP main pump housing. The status of the bearing support/axial spring cartridge interface is investigated under current loading conditions. An ANSYS version 4.3, three-dimensional, finite element model was generated on Lockheed's VAX 11/785 computer. A nonlinear thermal analysis was then executed on the Marshall Space Flight Center Engineering Analysis Data System (EADS). These thermal results were then applied along with the interference fit and bolt preloads to the model as load conditions for a static analysis to determine the gap status of the bearing support/axial spring cartridge interface. For possible further analysis of the local regions of HPOTP main pump housing assembly, detailed ANSYS submodels were generated using I-DEAS Geomod and Supertab (Appendix A).

Study of VLCC tanker ship damage stability during off-shore operation

NASA Astrophysics Data System (ADS)

Hanzu-Pazara, R.; Arsenie, P.; Duse, A.; Varsami, C.

2016-08-01

Today, for the carriage of crude oil on sea are used larger tanker ships, especially from VLCC class. The operation of this type of ships requires in many cases special conditions, mainly related to water depth in the terminal area and enough maneuvering space for entrance and departure. Because, many ports from all over the world don't have capacity to operate this type of ships inside, in designed oil terminal, have chosen for development of outside terminals, off-shore oil terminals. In case of this type of terminals, the problems of water depth and manoeuvring space are fixed, but other kind of situations appears, regarding the safety in operation and environment factors impact on ship during mooring at oil transfer buoy. In the present paper we intend to show a study made using simulation techniques about VLCC class tanker ship in case of a damage condition resulted after a possible collision with another ship during loading operation at an off-shore terminal. From the beginning, we take in consideration that the ship intact stability, during all loading possible situations, has to be high enough, so that in case of some damage with flooding of different compartments due to hypothetical dimension water hole, the ship stability in the final stage of flooding to correspond to the requirements for damage stability and, also, to complementary requirements for damage ship stability.

Proton exchange membrane fuel cells for space and electric vehicle applications: From basic research to technology development

NASA Technical Reports Server (NTRS)

Srinivasan, Supramaniam; Mukerjee, Sanjeev; Parthasarathy, A.; CesarFerreira, A.; Wakizoe, Masanobu; Rho, Yong Woo; Kim, Junbom; Mosdale, Renaut A.; Paetzold, Ronald F.; Lee, James

1994-01-01

The proton exchange membrane fuel cell (PEMFC) is one of the most promising electrochemical power sources for space and electric vehicle applications. The wide spectrum of R&D activities on PEMFC's, carried out in our Center from 1988 to date, is as follows (1) Electrode Kinetic and Electrocatalysis of Oxygen Reduction; (2) Optimization of Structures of Electrodes and of Membrane and Electrode Assemblies; (3) Selection and Evaluation of Advanced Proton Conducting Membranes and of Operating Conditions to Attain High Energy Efficiency; (4) Modeling Analysis of Fuel Cell Performance and of Thermal and Water Management; and (5) Engineering Design and Development of Multicell Stacks. The accomplishments on these tasks may be summarized as follows: (1) A microelectrode technique was developed to determine the electrode kinetic parameters for the fuel cell reactions and mass transport parameters for the H2 and O2 reactants in the proton conducting membrane. (2) High energy efficiencies and high power densities were demonstrated in PEMFCs with low platinum loading electrodes (0.4 mg/cm(exp 2) or less), advanced membranes and optimized structures of membrane and electrode assemblies, as well as operating conditions. (3) The modeling analyses revealed methods to minimize mass transport limitations, particularly with air as the cathodic reactant; and for efficient thermal and water management. (4) Work is in progress to develop multi-kilowatt stacks with the electrodes containing low platinum loadings.

The role of gas heat pumps in electric DSM

NASA Astrophysics Data System (ADS)

Fulmer, M.; Hughes, P. J.

1993-05-01

Natural gas-fired heat pumps (GHP's), an emerging technology, may offer environmental economic, and energy benefits relative to standard and advanced space conditioning equipment now on the market. This paper describes an analysis of GHP's for residential space heating, and cooling relative to major competing technologies under an Integrated Resource (IRP) framework. Our study models a hypothetical GHP rebate program using conditions typical of the Great Lakes region. The analysis is performed for a base scenario with sensitivity cases. In the base scenario, the GHP program is cost-effective according to the societal test, total resource cost test (TRC), and the participant test, but is not cost-effective according to the non-participant test. The sensitivity analyses indicate that the results for the TRC test are most sensitive to the season in which electric demand peaks and the technology against which the GHP's are competing, and are less sensitive to changes in the marginal administrative costs. The modeled GHP program would save 900 million kWh over the life of the program and reduce peak load by about 100 MW in winter and about 135 MW in summer. We estimate all of the GHP's in service (both GHP's of program participants and nonparticipants) in the case study region would save 1,900 million kWh and reduce summer peak load by over 350 MW.

Using observed load distributions with a simple model to analyse the epidemiology of sea lice (Lepeophtheirus salmonis) on sea trout (Salmo trutta).

PubMed

Murray, Alexander G

2002-06-01

Sea lice are ectoparasites of salmonids that have been associated with the recent decline in sea trout numbers in north-west Europe. Observed patterns of louse load distribution between sea trout in the seas surrounding the UK, Ireland and Norway and a simple model have been used to analyse the epidemiology of lice. Loads are aggregated and deviate strongly from the Poisson distribution, although less than is observed with many other parasites. The louse numbers on fish from offshore sites are slightly less variable than for fish from coastal sites with comparable mean loads. Analysis of louse development stages and sexes shows that selection between hosts by sea lice plays a limited role. If host selection is absent, then associated poor condition would be caused by, not the cause of, high louse burdens; however the absence of such selection is not proved. Scenarios with infection that is patchy in space and time best generate the aggregated load patterns observed; these patches accord with observed swarms of copepodids. Prevalence patterns may indicate the movement of trout between environments. Control of copepodids in infection 'hot spots', either directly or through control of louse egg production in their catchment, may reduce louse loads on wild sea trout and, in particular, extreme and damaging loads.

Design and implementation of fast bipolar clock drivers for CCD imaging systems in space applications

NASA Astrophysics Data System (ADS)

Jayarajan, Jayesh; Kumar, Nishant; Verma, Amarnath; Thaker, Ramkrishna

2016-05-01

Drive electronics for generating fast, bipolar clocks, which can drive capacitive loads of the order of 5-10nF are indispensable for present day Charge Coupled Devices (CCDs). Design of these high speed bipolar clocks is challenging because of the capacitive loads that have to be driven and a strict constraint on the rise and fall times. Designing drive electronics circuits for space applications becomes even more challenging due to limited number of available discrete devices, which can survive in the harsh radiation prone space environment. This paper presents the design, simulations and test results of a set of such high speed, bipolar clock drivers. The design has been tested under a thermal cycle of -15 deg C to +55 deg C under vacuum conditions and has been designed using radiation hardened components. The test results show that the design meets the stringent rise/fall time requirements of 50+/-10ns for Multiple Vertical CCD (VCCD) clocks and 20+/-5ns for Horizontal CCD (HCCD) clocks with sufficient design margins across full temperature range, with a pixel readout rate of 6.6MHz. The full design has been realized in flexi-rigid PCB with package volume of 140x160x50 mm3.

SO2 trajectories in a complex terrain environment using CALPUFF dispersion model, OMI and MODIS data

NASA Astrophysics Data System (ADS)

Sagan, Vasit; Pasken, Robert; Zarauz, Jorge; Krotkov, Nickolay

2018-07-01

Latest improvements in the resolution of atmospheric satellite sensors that measure chemical constituents from space have led to enhanced detection of trace gases. This paper explores the use of sulfur dioxide (SO2) level 2 dataset from OMI instrument, in conjunction with aerosol optical depth and Ångström exponent data from MODIS spectroradiometer, to estimate SO2 loads under clear and turbid atmospheres. The spatial patterns of SO2 loads in polluted atmospheric conditions are compared with a regional pollutant dispersion model (CALPUFF) and field observations near the Andes Peruvian city La Oroya, which is one of the most polluted places in the world. The efficacy of this methodology is further examined incorporating synchronous wind vectors. Results show that the spatial-temporal dynamics of OMI SO2 is in agreement with field measurements and CALPUFF. The SO2 satellite data obtained under optimal viewing conditions and clear skies are also compared with field observations. A correlation is found between in-situ measurements and OMI estimations. The correlation increases for days with predominantly fine aerosols when Ångström exponents are between 0.7 and 1. Moreover, pixel averaging techniques and low and high spatial frequency filtration, applied to OMI SO2 data, results in a more reliable representation of the mean SO2 plume. The paper concludes that anthropogenic SO2 can be monitored from space, even for turbid sky conditions. This demonstrates the potential for the use of satellite products to improve the air quality prediction models.

Space Station thermal storage/refrigeration system research and development

NASA Astrophysics Data System (ADS)

Dean, W. G.; Karu, Z. S.

1993-02-01

Space Station thermal loading conditions represent an order of magnitude increase over current and previous spacecraft such as Skylab, Apollo, Pegasus III, Lunar Rover Vehicle, and Lockheed TRIDENT missiles. Thermal storage units (TSU's) were successfully used on these as well as many applications for ground based solar energy storage applications. It is desirable to store thermal energy during peak loading conditions as an alternative to providing increased radiator surface area which adds to the weight of the system. Basically, TSU's store heat by melting a phase change material (PCM) such as a paraffin. The physical property data for the PCM's used in the design of these TSU's is well defined in the literature. Design techniques are generally well established for the TSU's. However, the Space Station provides a new challenge in the application of these data and techniques because of three factors: the large size of the TSU required, the integration of the TSU for the Space Station thermal management concept with its diverse opportunities for storage application, and the TSU's interface with a two-phase (liquid/vapor) thermal bus/central heat rejection system. The objective in the thermal storage research and development task was to design, fabricate, and test a demonstration unit. One test article was to be a passive thermal storage unit capable of storing frozen food at -20 F for a minimum of 90 days. A second unit was to be capable of storing frozen biological samples at -94 F, again for a minimum of 90 days. The articles developed were compatible with shuttle mission conditions, including safety and handling by astronauts. Further, storage rack concepts were presented so that these units can be integrated into Space Station logistics module storage racks. The extreme sensitivity of spacecraft radiator systems design-to-heat rejection temperature requirements is well known. A large radiator area penalty is incurred if low temperatures are accommodated via a single centralized radiator system. As per the scope of work of this task, the applicability of refrigeration system tailored to meet the specialized requirements of storage of food and biological samples was investigated. The issues addressed were the anticipated power consumption and feasible designs and cycles for meeting specific storage requirements. Further, development issues were assessed related to the operation of vapor compression systems in micro-gravity addressing separation of vapor and liquid phases (via capillary systems).

Space Station thermal storage/refrigeration system research and development

NASA Technical Reports Server (NTRS)

Dean, W. G.; Karu, Z. S.

1993-01-01

Space Station thermal loading conditions represent an order of magnitude increase over current and previous spacecraft such as Skylab, Apollo, Pegasus III, Lunar Rover Vehicle, and Lockheed TRIDENT missiles. Thermal storage units (TSU's) were successfully used on these as well as many applications for ground based solar energy storage applications. It is desirable to store thermal energy during peak loading conditions as an alternative to providing increased radiator surface area which adds to the weight of the system. Basically, TSU's store heat by melting a phase change material (PCM) such as a paraffin. The physical property data for the PCM's used in the design of these TSU's is well defined in the literature. Design techniques are generally well established for the TSU's. However, the Space Station provides a new challenge in the application of these data and techniques because of three factors: the large size of the TSU required, the integration of the TSU for the Space Station thermal management concept with its diverse opportunities for storage application, and the TSU's interface with a two-phase (liquid/vapor) thermal bus/central heat rejection system. The objective in the thermal storage research and development task was to design, fabricate, and test a demonstration unit. One test article was to be a passive thermal storage unit capable of storing frozen food at -20 F for a minimum of 90 days. A second unit was to be capable of storing frozen biological samples at -94 F, again for a minimum of 90 days. The articles developed were compatible with shuttle mission conditions, including safety and handling by astronauts. Further, storage rack concepts were presented so that these units can be integrated into Space Station logistics module storage racks. The extreme sensitivity of spacecraft radiator systems design-to-heat rejection temperature requirements is well known. A large radiator area penalty is incurred if low temperatures are accommodated via a single centralized radiator system. As per the scope of work of this task, the applicability of refrigeration system tailored to meet the specialized requirements of storage of food and biological samples was investigated. The issues addressed were the anticipated power consumption and feasible designs and cycles for meeting specific storage requirements. Further, development issues were assessed related to the operation of vapor compression systems in micro-gravity addressing separation of vapor and liquid phases (via capillary systems).

Quantitative controls on submarine slope failure morphology

USGS Publications Warehouse

Lee, H.J.; Schwab, W.C.; Edwards, B.D.; Kayen, R.E.

1991-01-01

The concept of the steady-state of deformation can be applied to predicting the ultimate form a landslide will take. The steady-state condition, defined by a line in void ratio-effective stress space, exists at large levels of strain and remolding. Conceptually, if sediment initially exists with void ratio-effective stress conditions above the steady-state line, the sediment shear strength will decrease during a transient loading event, such as an earthquake or storm. If the reduced shear strength existing at the steady state is less than the downslope shear stress induced by gravity, then large-scale internal deformation, disintegration, and flow will occur. -from Authors

Analysis of symmetric cross-ply laminated elastic plates using a higher-order theory. II - Buckling and free vibration

NASA Technical Reports Server (NTRS)

Khdeir, A. A.; Librescu, L.

1988-01-01

A previously developed higher-order plate theory and a technique based on the state space concept are used to investigate free vibration and buckling problems of rectangular cross-ply laminated plates. Unified results are presented for the case of arbitrary boundary conditions on two opposite edges. Good agreement is obtained with previous data for simply supported edge conditions. It is pointed out that classical laminated plate theory tends to overpredict both eigenfrequencies and buckling loads, leading to an increase of the degree of orthotropicity of individual layers and of the thickness ratio of the plate.

Effect of Soft Tissue Releases on Joint Space Opening in Total Knee Arthroplasty.

PubMed

Burkhart, Timothy A; Perry, Kevin I; Dobbin, Emily; Howard, James; Lanting, Brent

2016-12-01

The purpose of this study was to determine the gap achieved to the medial and lateral compartments following sectioning and release of the relevant soft tissues in preparation for a total knee arthroplasty. A custom-designed knee tensioner allowed the application of forces to the medial and lateral compartments of 12 cadaveric knee specimens. Loads of 100 N and 200 N were applied to each compartment, and the resulting displacement was measured in the following conditions: (1) All soft tissues intact, (2) an arthrotomy, (3) anterior cruciate ligament (ACL) sectioned, (4) posterior cruciate ligament (PCL) sectioned, and (5) release of the anterior aspect of the deep medial collateral ligament (MCL) fibers. Tensions were applied for all conditions from 90° to 0° of knee flexion in 30° increments. No differences were found in medial or lateral displacement after the arthrotomy or releasing the ACL or PCL at either 100 N or 200 N. At the 100 N load application, there was a significant increase in gap width when the anterior portion of the deep MCL was released (7.49 mm) compared to the intact (5.28 mm) and arthrotomy (5.75 mm) conditions. With respect to the 200 N load application, there were statistically significant differences detected between the deep MCL fiber release (11.09 mm) and intact conditions (8.05 mm) and release of the deep MCL and arthrotomy conditions (8.77 mm). The medial parapetellar arthrotomy, ACL and PCL sectioning did not result in medial or lateral displacement changes. The release of the anterior fibers of the deep MCL as part of the surgical exposure increased the medial gap magnitude. Copyright © 2016 Elsevier Inc. All rights reserved.

Creep-Fatigue Relationsihps in Electroactive Polymer Systems and Predicted Effects in an Actuator Design

NASA Technical Reports Server (NTRS)

Vinogradov, Aleksandra M.; Ihlefeld, Curtis M.; Henslee, Issac

2009-01-01

The paper concerns the time-dependent behavior of electroactive polymers (EAP) and their use in advanced intelligent structures for space exploration. Innovative actuator design for low weight and low power valves required in small plants planned for use on the moon for chemical analysis is discussed. It is shown that in-depth understanding of cyclic loading effects observed through accelerated creep rates due to creep-fatigue interaction in polymers is critical in terms of proper functioning of EAP based actuator devices. In the paper, an overview of experimental results concerning the creep properties and cyclic creep response of a thin film piezoelectric polymer polyvinylidene fluoride (PVDF) is presented. The development of a constitutive creep-fatigue interaction model to predict the durability and service life of electroactive polymers is discussed. A novel method is proposed to predict damage accumulation and fatigue life of polymers under oyclic loading conditions in the presence of creep. The study provides a basis for ongoing research initiatives at the NASA Kennedy Space Center in the pursuit of new technologies using EAP as active elements for lunar exploration systems.