1991 NASA Life Support Systems Analysis workshop

The 1991 Life Support Systems Analysis Workshop was sponsored by NASA Headquarters' Office of Aeronautics and Space Technology (OAST) to foster communication among NASA, industrial, and academic specialists, and to integrate their inputs and disseminate information to them. The overall objective of systems analysis within the Life Support Technology Program of OAST is to identify, guide the development of, and verify designs which will increase the performance of the life support systems on component, subsystem, and system levels for future human space missions. The specific goals of this workshop were to report on the status of systems analysis capabilities, to integrate the chemical processing industry technologies, and to integrate recommendations for future technology developments related to systems analysis for life support systems. The workshop included technical presentations, discussions, and interactive planning, with time allocated for discussion of both technology status and time-phased technology development recommendations. Key personnel from NASA, industry, and academia delivered inputs and presentations on the status and priorities of current and future systems analysis methods and requirements

Simulation verification techniques study

Results are summarized of the simulation verification techniques study which consisted of two tasks: to develop techniques for simulator hardware checkout and to develop techniques for simulation performance verification (validation). The hardware verification task involved definition of simulation hardware (hardware units and integrated simulator configurations), survey of current hardware self-test techniques, and definition of hardware and software techniques for checkout of simulator subsystems. The performance verification task included definition of simulation performance parameters (and critical performance parameters), definition of methods for establishing standards of performance (sources of reference data or validation), and definition of methods for validating performance. Both major tasks included definition of verification software and assessment of verification data base impact. An annotated bibliography of all documents generated during this study is provided

V&V of Lexical, Syntactic and Semantic Properties for Interactive Systems Through Model Checking of Formal Description of Dialog

International audienceDuring early phases of the development of an interactive system, future system properties are identified (through interaction with end users in the brainstorming and prototyping phase of the application, or by other stakeholders) imposing requirements on the final system. They can be specific to the application under development or generic to all applications such as usability principles. Instances of specific properties include visibility of the aircraft altitude, speed… in the cockpit and the continuous possibility of disengaging the autopilot in whatever state the aircraft is. Instances of generic properties include availability of undo (for undoable functions) and availability of a progression bar for functions lasting more than four seconds. While behavioral models of interactive systems using formal description techniques provide complete and unambiguous descriptions of states and state changes, it does not provide explicit representation of the absence or presence of properties. Assessing that the system that has been built is the right system remains a challenge usually met through extensive use and acceptance tests. By the explicit representation of properties and the availability of tools to support checking these properties, it becomes possible to provide developers with means for systematic exploration of the behavioral models and assessment of the presence or absence of these properties. This paper proposes the synergistic use two tools for checking both generic and specific properties of interactive applications: Petshop and Java PathFinder. Petshop is dedicated to the description of interactive system behavior. Java PathFinder is dedicated to the runtime verification of Java applications and as an extension dedicated to User Interfaces. This approach is exemplified on a safety critical application in the area of interactive cockpits for large civil aircrafts

Synergistic Development, Test, and Qualification Approaches for the Ares I and V Launch Vehicles

The U.S. National Aeronautics and Space Administration (NASA) initiated plans to develop the Ares I and Ares V launch vehicles in 2005 to meet the mission objectives for future human exploration of space. Ares I is designed to provide the capability to deliver the Orion crew exploration vehicle (CEV) to low-Earth orbit (LEO), either for docking to the International Space Station (ISS) or docking with an Earth departure stage (EDS) and lunar lander for transit to the Moon. Ares V provides the heavy-lift capability to deliver the EDS and lunar lander to orbit. An integrated test plan was developed for Ares I that includes un-crewed flight validation testing and ground testing to qualify structural components and propulsion systems prior to operational deployment. The overall test program also includes a single development test flight conducted prior to the Ares I critical design review (CDR). Since the Ares V concept was formulated to maximize hardware commonality between the Ares V and Ares I launch vehicles, initial test planning for Ares V has considered the extensibility of test approaches and facilities from Ares I. The Ares V test plan was part of a successful mission concept review (MCR) in 2008

Advanced reliability modeling of fault-tolerant computer-based systems

Two methodologies for the reliability assessment of fault tolerant digital computer based systems are discussed. The computer-aided reliability estimation 3 (CARE 3) and gate logic software simulation (GLOSS) are assessment technologies that were developed to mitigate a serious weakness in the design and evaluation process of ultrareliable digital systems. The weak link is based on the unavailability of a sufficiently powerful modeling technique for comparing the stochastic attributes of one system against others. Some of the more interesting attributes are reliability, system survival, safety, and mission success

Eliminating or Controlling System Risks via Effective System Safety Requirements and Standards

When addressing system risks, an overly simplistic supposition exists when an analyst assumes that once single hazards are identified and hazard controls are applied, the job of the safety engineer is complete. Such a mindset is literally dangerous in that potential system accidents may not have been identified and mitigated. System accidents may be the result of many hazards that under specific circumstances form an adverse progression, resulting in harm. Consider that there may be systemic and synergistic risks associated with a system. Designers are generally concerned with meeting a customer’s needs; however, in many situations, neither the customer nor the designer may be aware of systemic and synergistic risks related to a particular design. Experience shows that more than 50 percent of requirements are either not defined or not articulated clearly by the customer. Given that there may be non-apparent system hazards that present systemic and synergistic risks, how then are effective system safety requirements and standards developed to assure that system risks are eliminated or controlled to acceptable levels? The following discussion provides concepts, criteria and considerations to provide context and answer the proposed question

Introducing Model-based Design Methodology with LabVIEW to Teaching ARM-based Embedded System Design

This paper presents our latest experience of introducing the new topic of model-based design (MBD) concepts and tools to a Programming Tools (PT) course for educating students to be capable of utilizing modern tools for correctly developing complicated ARM-based embedded systems. It describes the course contents, student outcomes and lecture and lab preparation for teaching this topic with the emphasis on two sub-topics. Firstly, we present the details of using NI LabVIEW tool in programming ARM Cortex-M MCUs or ARM Cortex-A9 MCUs on the embedded device like NI myRIO for fast developing embedded applications. Secondly, to integrate an on-going research effort on the model-based verification into this course, we also introduce model-checking and the tools that have been utilized in the research project. This new topic helps introducing students the latest research advances which promote the wide applications of the MBD in safety-critical embedded applications. Our primary experience shows that the project-based learning approach with the graphical programming tools and selected MCUs is efficient and practical to teach the MBD of 32-bit MCUs programming