Refine Your Search

Topic

Author

Affiliation

Search Results

Technical Paper

Waste and Hygiene Compartment for the International Space Station

2001-07-09
2001-01-2225
The Waste and Hygiene Compartment will serve as the primary facility for metabolic waste management and personal hygiene on the United States segment of the International Space Station. The Compartment encloses the volume of two standard ISS racks and will be installed into Node 3 after launch inside a Multipurpose Logistics Module on the Space Shuttle. Long duration space flight requires a departure from the established hygiene and waste disposal practices employed on the Space Shuttle. This paper describes requirements and a conceptual design for the Waste and Hygiene Compartment that are both logistically practical and acceptable to the crew.
Technical Paper

Using R744 (CO2) to Cool an Up-Armored M1114 HMMWV

2005-05-10
2005-01-2024
The US Army uses a light tactical High-Mobility Multi-Purpose Wheeled Vehicle (HMMWV) which, due to the amount of armor added, requires air conditioning to keep its occupants comfortable. The current system uses R134a in a dual evaporator, remote-mounted condenser, engine-driven compressor system. This vehicle has been adapted to use an environmentally friendly refrigerant (carbon dioxide) to provide performance, efficiency, comfort and logistical benefits to the Army. The unusual thermal heat management issues and the fact that the vehicle is required to operate under extreme ambient conditions have made the project extremely challenging. This paper is a continuation of work presented at the SAE Alternate Refrigerants Symposium held in Phoenix last June [1].
Technical Paper

The State of ISS ATCS Design, Assembly and Operation

2003-07-07
2003-01-2513
The International Space Station (ISS) Active Thermal Control System (ATCS) (Ref. 1,2) has changed over the past several years to address problems and to improve its assembly and operation on-orbit. This paper captures the ways in which the Internal (I) ATCS and External (E) ATCS have changed design characteristics and operations both for the system currently operating on-orbit and the new elements of the system that are about to be added and/or activated. The rationale for changes in ATCS design, assembly and operation will provide insights into the lessons learned during ATCS development. The state of the assembly of the integrated ATCS will be presented to provide a status of the build-up of the system. The capabilities of the on-orbit system will be presented with a summary of the elements of the ISS ATCS that are functional on-orbit plus the plans for launch of remaining parts of the integrated ISS ATCS.
Technical Paper

The CEV Smart Buyer Team Effort: A Summary of the Crew Module & Service Module Thermal Design Architecture

2007-07-09
2007-01-3046
The NASA-wide CEV Smart Buyer Team (SBT) was assembled in January 2006 and was tasked with the development of a NASA in-house design for the CEV Crew Module (CM), Service Module (SM), and Launch Abort System (LAS). This effort drew upon over 250 engineers from all of the 10 NASA Centers. In 6 weeks, this in-house design was developed. The Thermal Systems Team was responsible for the definition of the active and passive design architecture. The SBT effort for Thermal Systems can be best characterized as a design architecting activity. Proof-of-concepts were assessed through system-level trade studies and analyses using simplified modeling. This nimble design approach permitted definition of a point design and assessing its design robustness in a timely fashion. This paper will describe the architecting process and present trade studies and proposed thermal designs
Technical Paper

The Advanced Life Support Human-Rated Test Facility: Testbed Development and Testing to Understand Evolution to Regenerative Life Support

1996-07-01
961592
As part of its integrated system test bed capability, NASA's Advanced Life Support Program has undertaken the development of a large-scale advanced life support facility capable of supporting long-duration testing of integrated, regenerative biological and physicochemical life support systems. This facility--the Advanced Life Support Human-Rated Test Facility (HRTF) is currently being built at the Johnson Space Center. The HRTF is comprised of a series of interconnected chambers with a sealed internal environment capable of supporting a test crew of four for periods exceeding one year. The life support system will consist of both biological and physicochemical components and will perform air revitalization, water recovery, food production, solid waste processing, thermal management, and integrated command and control functions. Currently, a portion of this multichamber facility has been constructed and is being outfitted with basic utilities and infrastructure.
Technical Paper

The Advanced Design of a Liquid Cooling Garment Through Long-Term Research: Implications of the Test Results on Three Different Garments

2009-07-12
2009-01-2517
The most recent goal of our research program was to identify the optimal features of each of three garments to maintain core temperature and comfort under intensive physical exertion. Four males and 2 females between the ages of 22 and 46 participated in this study. The garments evaluated were the MACS-Delphi, Russian Orlan, and NASA LCVG. Subjects were tested on different days in 2 different environmental chamber temperature/humidity conditions (24°C/H∼28%; 35°C/H∼20%). Each session consisted of stages of treadmill walking/running (250W to 700W at different stages) and rest. In general, the findings showed few consistent differences among the garments. The MACS-Delphi was better able to maintain subjects within a skin and core temperature comfort zone than was evident in the other garments as indicated by a lesser fluctuation in temperatures across physical exertion levels.
Technical Paper

System Engineering and Integration of Controls for Advanced Life Support

2006-07-17
2006-01-2121
The Advanced Integration Matrix (AIM) project at the Johnson Space Center (JSC) was chartered to study and solve systems-level integration issues for exploration missions. One of the first issues identified was an inability to conduct trade studies on control system architectures due to the absence of mature evaluation criteria. Such architectures are necessary to enable integration of regenerative life support systems. A team was formed to address issues concerning software and hardware architectures and system controls.. The team has investigated what is required to integrate controls for the types of non-linear dynamic systems encountered in advanced life support. To this end, a water processing bioreactor testbed is being developed which will enable prototyping and testing of integration strategies and technologies.
Technical Paper

Standardized Radiation Shield Design Method: 2005 HZETRN

2006-07-17
2006-01-2109
Research committed by the Langley Research Center through 1995 resulting in the HZETRN code provides the current basis for shield design methods according to NASA STD-3000 (2005). With this new prominence, the database, basic numerical procedures, and algorithms are being re-examined with new methods of verification and validation being implemented to capture a well defined algorithm for engineering design processes to be used in this early development phase of the Bush initiative. This process provides the methodology to transform the 1995 HZETRN research code into the 2005 HZETRN engineering code to be available for these early design processes. In this paper, we will review the basic derivations including new corrections to the codes to insure improved numerical stability and provide benchmarks for code verification.
Technical Paper

Software Reliability Growth Modeling: Comparison between Non-Linear- Regression Estimation and Maximum-Likelihood-Estimator Procedures

2018-09-10
2018-01-1772
Automotive software complexity has been growing rapidly with time. The demand for automation in automotive segment including autonomous automobiles and software based products has caught the attention of researchers. Hence, it is necessary to check the complexity of automotive software and their reliability growth. Testing in the field of software artifact is resource intensive exercise. If project managers are able to put forward testing activities well then the testing resource consumptions may be much more resource/cost efficient. Reliability can be estimated during testing phase of software using software reliability growth models (SRGMs). A software package Computer Aided Software Reliability Estimation (CASRE) has many important SRGMs. These SRGMs are based on Non-Homogeneous Poisson Process (NHPP), Markov process or Bayesian models.
Technical Paper

Smart Icing Systems for Aircraft Icing Safety

2003-06-16
2003-01-2100
Aircraft incidents and accidents in icing are often the result of degradation in performance and control. However, current ice sensors measure the amount of ice and not the effect on performance and control. No processed aircraft performance degradation information is available to the pilot. In this paper research is reported on a system to estimate aircraft performance and control changes due to ice, then use this information to automatically operate ice protection systems, provide aircraft envelope protection and, if icing is severe, adapt the flight controls. Key to such a safety system would be he proper communication to, and coordination with, the flight crew. This paper reviews the basic system concept, as well as the research conducted in three critical areas; aerodynamics and flight mechanics, aircraft control and identification, and human factors.
Technical Paper

Simulation Study of Space Suit Thermal Control

2000-07-10
2000-01-2391
Automatic thermal comfort control for the minimum consumables PLSS is undertaken using several control approaches. Accuracy and performance of the strategies using feedforward, feedback, and gain scheduling are evaluated through simulation, highlighting their advantages and limitations. Implementation issues, consumable usage, and the provision for the extension of these control strategies to the cryogenic PLSS are addressed.
Technical Paper

Safety Concerns in Automatic Control of Heavy-Duty Articulated Vehicles

2004-10-26
2004-01-2717
Control system design is one of the most critical issues for implementation of intelligent vehicle systems. Wide ranged fundamental research has been undertaken in this area and the safety issues of the fully automated vehicles are clearly recognized. Study of vehicle performance constrains is essential for a good understanding of this problem. This paper discusses safety issues of heavy-duty vehicles under automatic steering control. It focuses on the analysis of the effect of tire force saturation. Vehicle handling characteristics are also analyzed to improve understanding of the truck dynamics and control tasks. A simple differential brake control is formulated to show its effect of on reducing trailer swing.
Technical Paper

Revised Solid Waste Model for Mars Reference Missions

2002-07-15
2002-01-2522
A key component of an Advanced Life Support (ALS) system is the solid waste handling system. One of the most important data sets for determining what solid waste handling technologies are needed is a solid waste model. A preliminary solid waste model based on a six-person crew was developed prior to the 2000 Solid Waste Processing and Resource Recovery (SWPRR) workshop. After the workshop, comments from the ALS community helped refine the model. Refinements included better estimates of both inedible plant biomass and packaging materials. Estimates for Extravehicular Mobility Unit (EMU) waste, water processor brine solution, as well as the water contents for various solid wastes were included in the model refinement efforts. The wastes were re-categorized and the dry wastes were separated from wet wastes. This paper details the revised model as of the end of 2001. The packaging materials, as well as the biomass wastes, vary significantly between different proposed Mars missions.
Technical Paper

Reconfigurable Control System Design for Future Life Support Systems

2008-06-29
2008-01-1976
A reconfigurable control system is an intelligent control system that detects faults within the system and adjusts its performance automatically to avoid mission failure, save lives, and reduce system maintenance costs. The concept was first successfully demonstrated by NASA between December 1989 and March 1990 on the F-15 flight control system (SRFCS), where software was integrated into the aircraft's digital flight control system to compensate for component loss by reconfiguring the remaining control loop. This was later adopted in the Boeing X-33. Other applications include modular robotics, reconfigurable computing structure, and reconfigurable helicopters. The motivation of this work is to test such control system designs for future long term space missions, more explicitly, the automation of life support systems.
Technical Paper

Program Development for Exercise Countermeasures

1992-07-01
921140
Research indicates that adaptation to a microgravity environment includes physiological changes to the cardiovascular-respiratory, musculoskeletal, and neurosensory systems. Many of these alterations emerge even during space flights of short duration. Therefore, the advancement of manned space flight from Shuttle to Space Station Freedom (SSF) requires development of effective methods for augmenting the ability of humans to maintain functional performance. Thus, it is the goal of NASA to minimize the consequences of microgravity-induced deconditioning to provide optimal in-flight performance (intra- and extra-vehicular activities), suitable return to a pedestrian environment, and nominal physiological postflight recovery for an expeditious return-to-flight physical status.
Technical Paper

Phase VI Advanced EVA Glove Development and Certification for the International Space Station

2001-07-09
2001-01-2163
Since the early 1980’s, the Shuttle Extra Vehicular Activity (EVA) glove design has evolved to meet the challenge of space based tasks. These tasks have typically been satellite retrieval and repair or EVA based flight experiments. With the start of the International Space Station (ISS) assembly, the number of EVA based missions is increasing far beyond what has been required in the past; this has commonly been referred to as the “Wall of EVA’s”. To meet this challenge, it was determined that the evolution of the current glove design would not meet future mission objectives. Instead, a revolution in glove design was needed to create a high performance tool that would effectively increase crewmember mission efficiency. The results of this effort have led to the design, certification and implementation of the Phase VI EVA glove into the Shuttle flight program.
Technical Paper

Performance Evaluation of Candidate Space Suit Elements for the Next Generation Orbital EMU

1992-07-01
921344
The projections of increased Extravehicular Activity (EVA) operations for the Space Station Freedom (SSF) resulted in the development of advanced space suit technologies to increase EVA efficiency. To eliminate the overhead of denitrogenation, candidate higher-operating pressure suit technologies were developed. The AX-5 all metallic, multi-bearing technologies were developed at the Ames Research Center, and the Mk. III fabric and metallic technologies were developed at the Johnson Space Center. Following initial technology development, extensive tests and analyses were performed to evaluate all aspects of candidate technology performance. The current Space Shuttle space suit technologies were used as a baseline for evaluating those of the AX-5 and Mk. III. Tests included manned evaluations in the Weightless Environment Training Facility and KC-135 zero-gravity aircraft.
Technical Paper

Overview of Potable Water Systems on Spacecraft Vehicles and Applications for the Crew Exploration Vehicle (CEV)

2007-07-09
2007-01-3259
Providing water necessary to maintain life support has been accomplished in spacecraft vehicles for over forty years. This paper will investigate how previous U.S. space vehicles provided potable water. The water source for the spacecraft, biocide used to preserve the water on-orbit, water stowage methodology, materials, pumping mechanisms, on-orbit water requirements, and water temperature requirements will be discussed. Where available, the hardware used to provide the water and the general function of that hardware will also be detailed. The Crew Exploration Vehicle (CEV or Orion) water systems will be generically discussed to provide a glimpse of how similar they are to water systems in previous vehicles. Conclusions, questions, and recommendations on strategies that could be applied to CEV based on previous spacecraft water system lessons learned will be made.
Technical Paper

Overview of NASA's Thermal Control System Development for Exploration Project

2009-07-12
2009-01-2436
NASA's Constellation Program includes the Orion, Altair, and Lunar Surface Systems (LSS) project offices. The first two elements, Orion and Altair, are manned space vehicles while the third element is broader and includes several subelements including Rovers and a Lunar Habitat. The upcoming planned missions involving these systems and vehicles include several risks and design challenges. Due to the unique thermal environment, many of these risks and challenges are associated with the vehicles' thermal control system. NASA's Exploration Systems Mission Directorate (ESMD) includes the Exploration Technology Development Program (ETDP). ETDP consists of several technology development projects. The project chartered with mitigating the aforementioned risks and design challenges is the Thermal Control System Development for Exploration Project.
Technical Paper

Oversteer/Understeer Characteristics of a Locked Differential

1994-12-01
942485
The type of differential used in a vehicle has an important and often-neglected effect on handling performance. This is particularly important in racing applications, such as in IndyCar racing, in which the type of differential chosen depends on the course being raced (superspeedway ovals, short ovals, temporary street courses and permanent road courses). In the present work, we examine the effect of a locked rear differential on oversteer/understeer behavior. Using a linear tire model, it is shown that employing a locked differential adds a constant understeer offset to the steering wheel angle (SWA) -v- lateral acceleration vehicle signature. A computer simulation of steady-state cornering behavior showed that the actual effect is much more complicated, and is strongly influenced by static weight distribution, front/rear roll couple distribution, available traction and the radius of the turn being negotiated.
X