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Standard

(ISO/IEC 12207) Standard for Information Technology - Software Life Cycle Processes

2015-07-01
CURRENT
IEEEEIA12207_0
ISO/IEC 12207 provides a common framework for developing and managing software. IEEE/EIA 12207.0 consists of the clarifications, additions, and changes accepted by the Institute of Electrical and Electronics Engineers (IEEE) and the Electronic Industries Alliance (EIA) as formulated by a joint project of the two organizations. IEEE/EIA 12207.0 contains concepts and guidelines to foster better understanding and application of the standard. Thus this standard provides industry a basis for software practices that would be usable for both national and international business.
Technical Paper

10 KWe Dual-Mode Space Nuclear Power System for Military and Scientific Applications

1992-08-03
929072
A 10 KWe dual-mode space power system concept has been identified which is based on INEL's Small Externally-fueled Heat Pipe Thermionic Reactor (SEHPTR) concept. This power system will enhance user capabilities by providing reliable electric power and by providing two propulsion systems; electric power for an arc-jet electric propulsion system and direct thrust by heating hydrogen propellant inside the reactor. The low thrust electric thrusters allow efficient station keeping and long-term maneuvering. The direct thrust capability can provide tens of pounds of thrust at a specific impulse of around 730 seconds for maneuvers that must be performed more rapidly. The direct thrust allows the nuclear power system to move a payload from Low Earth Orbit (LEO) to Geosynchronous Earth Orbit (GEO) in less than one month using approximately half the propellant of a cryogenic chemical stage.
Technical Paper

1553 RT Mechanizations for Data Sample Consistency and Multi-Message Transfers

1993-04-01
931600
System requirements and Interface Control Drawings (ICDs) make a variety of demands for MIL-STD-1553 remote terminals (RTs). Among these requirements are the need to ensure data integrity and sample data consistency, the need to perform bulk (multi-message) data transfers, and the need to offload the operation of the host CPU to the greatest degree possible. This latter requirement is reflected in such specifications as CPU spare bandwidth. The latest 1553 terminals provide a variety of choices for performing the different types of transfers. This paper provides a discussion of the hardware and software techniques for achieving these objectives. Three different schemes for RT subaddress memory management are presented: single message, circular buffer, and double buffered. For receive and transmit messages, these include fully synchronous single message transfers, asynchronous single message transfers, and multi-message transfers.
Technical Paper

270-Vdc/Hybrid 115-Vac Electric Power Generating System Technology Demonstrator Evolution to a Dual-Channel, More Electric Aircraft Technology Development Testbed

1991-09-01
912183
Sundstrand has been investigating 270-Vdc/hybrid 115-Vac electrical power generating systems (EPGS) technology in preparation for meeting the electrical power generating system (EPGS) requirements for future aircraft (1). Systems such as the one being investigated are likely to be suitable for the More-Electric Aircraft (MEA) concepts presently under industry and military study. The present Sundstrand single-channel testbed is being further expanded to better understand the electrical system performance characteristics and power quality requirements of an MEA in which traditional mechanical subsystems are replaced by those of a “more-electric” nature. This paper presents the most recent Sundstrand 270-Vdc system transient performance data, and describes the modifications being made to the 270-Vdc/hybrid 115-Vac testbed.
Technical Paper

777 Wing and Engine Ice Protection System

1997-07-14
972260
This paper describes the wing and engine ice protection system, used on all 777 aircraft. The 777 ice protection system is unique in two ways: it has an advanced control system which minimizes aircraft power consumption. In addition, the system was procured by the prime contractor, Boeing, as a fully integrated subsystem from a single supplier.
Technical Paper

8000 psi Hydraulic System Seals and Materials Test Program-A Progress Report

1985-10-01
851913
Flight control technology for 8000 psi has emerged almost simultaneously with new fire-resistant hydraulic fluids, such as MIL-H-83282 and CTFE. A proliferation of industry recommendations has resulted in a wide variety of mechanisms for solving associated actuator design problems, including tighter clearances, special seals, finishes, materials, and many others. As there are few common agreements on the issues, an extensive three-phase test program was undertaken to attempt to corroborate some of these approaches or suggest others that may be better or more cost effective.
Technical Paper

8000 psi Hydraulic System Seals and Materials Test Program-Final Report

1987-10-01
871895
An 8000 psi test program was conducted to resolve conflicts and issues surrounding the use of CTFE and MIL-H-83282 fluid with vented and unvented actuator rod seals. Each of the four possible combinations had unique problems and each responded to appropriate corrections including new backup rings designed to operate with standard clearances. It was concluded that all combinations were viable within certain limits. Advantages and disadvantages of each configuration were identified and specific recommendations made for both dynamic and static seals within the context of existing military specifications.
Standard

8000 psi Hydraulic Systems: Experience and Test Results

1994-09-01
HISTORICAL
AIR4002
Shortly after World War II, as aircraft became more sophisticated and power-assist, flight-control functions became a requirement, hydraulic system operating pressures rose from the 1000 psi level to the 3000 psi level found on most aircraft today. Since then, 4000 psi systems have been developed for the U.S. Air Force XB-70 and B-1 bombers and a number of European aircraft including the tornado multirole combat aircraft and the Concorde supersonic transport. The V-22 Osprey incorporates a 5000 psi hydraulic system. The power levels of military aircraft hydraulic systems have continued to rise. This is primarily due to higher aerodynamic loading, combined with the increased hydraulic functions and operations of each new aircraft. At the same time, aircraft structures and wings have been getting smaller and thinner as mission requirements expand. Thus, internal physical space available for plumbing and components continues to decrease.
Standard

8000 psi Hydraulic Systems: Experience and Test Results

2012-11-15
CURRENT
AIR4002A
Shortly after World War II, as aircraft became more sophisticated and power-assist, flight-control functions became a requirement, hydraulic system operating pressures rose from the 1000 psi level to the 3000 psi level found on most aircraft today. Since then, 4000 psi systems have been developed for the U.S. Air Force XB-70 and B-1 bombers and a number of European aircraft including the tornado multirole combat aircraft and the Concorde supersonic transport. The V-22 Osprey incorporates a 5000 psi hydraulic system. The power levels of military aircraft hydraulic systems have continued to rise. This is primarily due to higher aerodynamic loading, combined with the increased hydraulic functions and operations of each new aircraft. At the same time, aircraft structures and wings have been getting smaller and thinner as mission requirements expand. Thus, internal physical space available for plumbing and components continues to decrease.
Technical Paper

A Brief Study of Conditionally Enabled Phase Compensated Rate Limiters

2008-08-19
2008-01-2256
This paper describes how airplane control surface rate limiting can enable a ‘cliff-like’ onset of Pilot-Induced Oscillation, (P.I.O.) and how the danger can be erased by implementation of Conditionally Enabled Phase Compensated Rate Limiters, (PCRLs), in the design of the airplane's flight control system. The application is particularly important for large airplanes where control surface actuator sizing and the associated hydraulic system volumetric flow rate capability cannot be generously over-sized without large weight and cost penalties. It is shown that the PCRL can remain inactive during normal airplane operations where RMS control commands are relatively small thus avoiding adverse control surface response effects that have hindered earlier PCRL acceptance.
Journal Article

A Centrally Managed Identity-Anonymized CAN Communication System*

2018-05-16
Abstract Identity-Anonymized CAN (IA-CAN) protocol is a secure CAN protocol, which provides the sender authentication by inserting a secret sequence of anonymous IDs (A-IDs) shared among the communication nodes. To prevent malicious attacks from the IA-CAN protocol, a secure and robust system error recovery mechanism is required. This article presents a central management method of IA-CAN, named the IA-CAN with a global A-ID, where a gateway plays a central role in the session initiation and system error recovery. Each ECU self-diagnoses the system errors, and (if an error happens) it automatically resynchronizes its A-ID generation by acquiring the recovery information from the gateway. We prototype both a hardware version of an IA-CAN controller and a system for the IA-CAN with a global A-ID using the controller to verify our concept.
Technical Paper

A Chemical Containment Model for the General Purpose Work Station

1994-06-01
941286
Contamination control is a critical safety requirement imposed on experiments flying on board the Spacelab. The General Purpose Work Station, a Spacelab support facility used for life sciences space flight experiments, is designed to remove volatile compounds from its internal airpath and thereby minimize contamination of the Spacelab. This is accomplished through the use of a large, multi-stage filter known as the Trace Contaminant Control System. Many experiments planned for the Spacelab require the use of toxic, volatile fixatives in order to preserve specimens prior to post-flight analysis. The NASA-Ames Research Center SLS-2 payload, in particular, necessitated the use of several toxic, volatile compounds in order to accomplish the many inflight experiment objectives of this mission. A model was developed based on earlier theories and calculations which provides conservative predictions of the resultant concentrations of these compounds given various spill scenarios.
Technical Paper

A Clutch for V/STOL

1977-02-01
770989
This paper describes the requirements, design, and early testing of a flight weight V/STOL clutch. A clutch is required between the combiner box and the forward or nose fan for some versions of V/STOL aircraft. This clutch has been designed to transmit 11,000 HP at fan drive speeds, and be capable of minimum engagement times and rapid cycling. This paper will cover the mechanical arrangement and control system of this clutch.
Journal Article

A Comparison between One- and Two-Loop ATCS Architectures Proposed for CEV

2009-07-12
2009-01-2458
In an effort to help future crewed spacecraft thermal control analysts understand the characteristics of one-and two-loop Active Thermal Control Systems (ATCS), a comparison was made between the one- and two-loop ATCS architectures officially proposed for the Crew Exploration Vehicle (CEV) in Design Analysis Cycle 1 (DAC1) and DAC2, respectively. This report provides a description of each design, along with mass and power estimates derived from their respective Master Equipment List (MEL) and Power Equipment List (PEL). Since some of the components were sized independent of loop architecture (ex. coldplates and heat exchangers), the mass and power for these components were based on the MEL and PEL of the most mature design (i.e. two-loop architecture). The mass and power of the two architectures are then compared and the ability of each design to meet CEV requirements is discussed.
Technical Paper

A Comparison of Numerical Techniques for the Study of Lightning Indirect Effects

2001-09-11
2001-01-2894
A comparison of various numerical tools and techniques was performed for calculating the lightning indirect effects to composite structures and internal systems. This paper is a summary of the initial comparison results. Detailed results of each technique considered are given in additional separate papers presented during this conference. The modeling considered current distributions over and within composite surfaces and the coupling of current and voltages to internal systems such as wire bundle cables and hydraulic and fuel tubes. The models were compared to each other and to measured data from low level swept continuous wave (LLCW) tests performed on two test fixtures. Other features of the codes such as run time, ease of use, computer requirements, availability of documentation and technical support, etc. are compared as well.
Journal Article

A Comparison of the Apollo and Early Orion Environmental Control, Life Support and Active Thermal Control System's Driving Requirements and System Mass

2008-06-29
2008-01-2081
The Orion Crew and Service Modules are often compared to the Apollo Command and Service Modules due to their similarity in basic mission objective: both were dedicated to getting a crew to lunar orbit and safely returning them to Earth. Both spacecraft rely on the environmental control, life support and active thermal control systems (ECLS/ATCS) for the basic functions of providing and maintaining a breathable atmosphere, supplying adequate amount of potable water and maintaining the crew and avionics equipment within certified thermal limits. This assessment will evaluate the driving requirements for both programs and highlight similarities and differences. Further, a short comparison of the two system architectures will be examined including a side by side assessment of some selected system's hardware mass.
Technical Paper

A Computer Aided Engineering Tool for ECLS Systems

1987-07-01
871423
This paper presents an overview of the Computer Aided Systems Engineering and Analysis (CASE/A)-ECLSS series which is designed as a generalised ECLSS design and analysis package. This system was developed under NASA MSEC contract NAS8-36407 to meet the Systems Analysis requirements of the Space Station ECLSS. The Space Station represents an order of magnitude increase in complexity over current Spacecraft technologies and will seriously tax current analysis techniques. This program is capable of simulating atmospheric revitalization systems, water recovery and management systems, and single phase active thermal control systems. The program evolved from both the G189A and the SINDA programs and shares the G189A architectural concepts. The designer/ analysis interface is graphics based and allows the designer to build a model by constructing a schematic of the system under consideration.
Technical Paper

A Computer Controlled Power Tool for Servicing the Hubble Space Telescope

1996-07-01
961531
The Hubble Space Telescope (HST) was designed to be serviced from the shuttle by astronauts performing extravehicular activities (EVA). During the first HST Servicing Mission (STS-61) two types of power tools were flown, the Power Ratchet Tool (PRT) and the HST Power Tool. Each tool had both benefits and drawbacks. An objective for the second HST servicing mission was to combine the reliability, accuracy, and programmability of the PRT with the pistol grip ergonomics and compactness of the HST Power Tool into a new tool called the EVA Pistol Grip Tool (PGT). The PGT is a self-contained, microprocessor controlled, battery powered, 3/8-inch drive hand-held tool. The PGT may also be used as a non-powered ratchet wrench. Numerous torque, speed, and turn or angle limits can be programmed into the PGT for use during various servicing missions. Batteries Modules are replaceable during ground, Intravehicular Activities (IVA), and EVA operations.
Technical Paper

A Concurrent Design/Analysis Tool for Aircraft Hydraulic Systems

1990-09-01
902004
This paper presents the results of an investigation to improve design/analysis techniques for aircraft hydraulic systems. A design/analysis tool was developed by integrating control-surface commands and loads obtained from Aircraft Dynamic Simulator Software (ADSS) with an enhanced version of the HYdraulic TRansient ANalysis (HYTRAN) program. Control-surface commands and loads from an ADSS simulation of a selected maneuver were used as dynamic input to the HYTRAN program so that the hydraulic system response could be predicted throughout the maneuver. Predicted hydraulic system pressures and control-surface positions from the HYTRAN simulation of the maneuver were compared to flight-test data and were found to be in excellent agreement. The successful coalescence of the two independent software programs gives engineers a concurrent design/analysis tool that can be used to optimize hydraulic system designs during the very early stages of design.
Technical Paper

A Control System for Managing and Replenishing Nutrient Solution Based on Electrical Conductivity

1998-07-13
981807
An automated nutrient replenishment system has been developed in order to provide a constant electrical conductivity (EC) value for the nutrient solution over the period of plant growth. A single nutrient film technique (NFT) system developed by the Tuskegee University NASA Center was equipped with the EC control system for growth trials with sweetpotatoes. The system is completely controlled and monitored by a PC through the use of LabView instrumentation and data acquisition software. A submersible EC probe driven by an EC controller measures the EC of the nutrient solution reservoir. EC values are passed from the controller to the PC through analog outputs. If the EC is outside a given range, the PC sends a signal to one of two solenoid valves that allow concentrated stock solution or deionized water to enter the reservoir to either raise or lower the EC respectively. For this application the set point is 1200μS cm-1, with a dead band from 1180 to 1220μS cm-1.
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