Space engine safety system

A rocket engine safety system was designed to initiate control procedures to minimize damage to the engine or vehicle or test stand in the event of an engine failure. The features and the implementation issues associated with rocket engine safety systems are discussed, as well as the specific concerns of safety systems applied to a space-based engine and long duration space missions. Examples of safety system features and architectures are given, based on recent safety monitoring investigations conducted for the Space Shuttle Main Engine and for future liquid rocket engines. Also, the general design and implementation process for rocket engine safety systems is presented

The application of neural networks to the SSME startup transient

Feedforward neural networks were used to model three parameters during the Space Shuttle Main Engine startup transient. The three parameters were the main combustion chamber pressure, a controlled parameter, the high pressure oxidizer turbine discharge temperature, a redlined parameter, and the high pressure fuel pump discharge pressure, a failure-indicating performance parameter. Network inputs consisted of time windows of data from engine measurements that correlated highly to the modeled parameter. A standard backpropagation algorithm was used to train the feedforward networks on two nominal firings. Each trained network was validated with four additional nominal firings. For all three parameters, the neural networks were able to accurately predict the data in the validation sets as well as the training set

Aerospike Engine Post-Test Diagnostic System Delivered to Rocketdyne

The NASA Glenn Research Center at Lewis Field, in cooperation with Rocketdyne, has designed, developed, and implemented an automated Post-Test Diagnostic System (PTDS) for the X-33 linear aerospike engine. The PTDS was developed to reduce analysis time and to increase the accuracy and repeatability of rocket engine ground test fire and flight data analysis. This diagnostic system provides a fast, consistent, first-pass data analysis, thereby aiding engineers who are responsible for detecting and diagnosing engine anomalies from sensor data. It uses analytical methods modeled after the analysis strategies used by engineers. Glenn delivered the first version of PTDS in September of 1998 to support testing of the engine s power pack assembly. The system was used to analyze all 17 power pack tests and assisted Rocketdyne engineers in troubleshooting both data acquisition and test article anomalies. The engine version of PTDS, which was delivered in June of 1999, will support all single-engine, dual-engine, and flight firings of the aerospike engine

Genetic algorithm based input selection for a neural network function approximator with applications to SSME health monitoring

A genetic algorithm is used to select the inputs to a neural network function approximator. In the application considered, modeling critical parameters of the space shuttle main engine (SSME), the functional relationship between measured parameters is unknown and complex. Furthermore, the number of possible input parameters is quite large. Many approaches have been used for input selection, but they are either subjective or do not consider the complex multivariate relationships between parameters. Due to the optimization and space searching capabilities of genetic algorithms they were employed to systematize the input selection process. The results suggest that the genetic algorithm can generate parameter lists of high quality without the explicit use of problem domain knowledge. Suggestions for improving the performance of the input selection process are also provided

Architektur für ein System zur Dokumentanalyse im Unternehmenskontext - Integration von Datenbeständen, Aufbau- und Ablauforganisation

Workflowmanagementsysteme werden im Bürobereich verstärkt zur effizienten Geschäftsprozeßabwicklung eingesetzt. Das bereits Mitte der 70er Jahre propagierte papierlose Büro bleibt jedoch gegenwärtig immer noch Utopie. Dieser Widerspruch liegt darin begründet, daß die Handhabung von papierintensiven Vorgängen in hohem Maße abhängig ist von einer Identifkation und Aufbereitung der in den Dokumenten enthaltenen Informationen. Allerdings müssen solche Daten z.B. bei eingehender Post immer noch von Hand eingegeben werden. In diesem Dokument wird die Architektur eines System vorgestellt, das diesen Medienbruch überwinden soll. Techniken aus dem Gebiet der Dokumentanalyse und des Dokumentverstehens werden in den Workftowkontext integriert und nutzen das dort verfügbare Wissen zur Steigerung der Erkennungsqualität. Das Architekturdokument beruht auf einer ebenfalls dokumentierten Anforderungsanalyse (DFKI Dokument D-97-05). Es enthält eine statische und eine dynamische Beschreibung der benötigten Klassenkategorien und erklärt deren Funktionalität anhand eines umfassenden Beispiels

Towards an integrated ecological-economic land-use change model

Land-use changes have transformed tropical landscapes throughout the past decades dramatically. We describe here an ecologicaleconomicland-use change model to provide an integrated, exploratory tool to analyze how tropical land use and land-use change affect ecological and socio-conomic functions. The guiding question of the model is what kind of landscape mosaic can improve the ensemble of ecosystem functioning, biodiversity and economic benefit based on the synergies and trade-offs that we have to account for. The economic submodel simulates smallholder land-use management decisions based on a profit maximization assumption and a Leontief production function. Each household determines factor inputs for all household fields and decides about land-use change based on available wealth. The ecological submodel includes a simple account of carbon sequestration in above- and belowground vegetation. Initialized with realistic or artificial land use maps, the ecological-economic model will advance our understanding of the mechanisms underlying the trade-offs and synergies of ecological and economic functions in tropical landscapes

Challenging the Postwar Narrative: The Art and Agenda of Boris Lurie

Art history is shaped, studied, and taught based on narratives, artistic movements, and the biographies of celebrated artists. While contributing to an understanding of prevalent traditions and artists working in those traditions, these narratives are also constructions of inclusion and exclusion that establish art historical placement for certain artists while relegating others to historical obscurity. It is clear what happens to the critical fortunes of artists who are placed within these narratives. Yet what happens to the artists who do not fit within any of the categories established by these constructions? Are they then to be understood as simply minor artists or perhaps even “outsider artists?” Using the example of Boris Lurie and his critical fortune within the context of the standard art historical narrative of American art of the post World War Two period, this thesis argues for an expanded vision of modern and contemporary art that would accommodate lesser-known artists and offer a nuanced understanding of what American art has been after 1945

Real-Time Sensor Validation, Signal Reconstruction, and Feature Detection for an RLV Propulsion Testbed

A real-time system for validating sensor health has been developed in support of the reusable launch vehicle program. This system was designed for use in a propulsion testbed as part of an overall effort to improve the safety, diagnostic capability, and cost of operation of the testbed. The sensor validation system was designed and developed at the NASA Lewis Research Center and integrated into a propulsion checkout and control system as part of an industry-NASA partnership, led by Rockwell International for the Marshall Space Flight Center. The system includes modules for sensor validation, signal reconstruction, and feature detection and was designed to maximize portability to other applications. Review of test data from initial integration testing verified real-time operation and showed the system to perform correctly on both hard and soft sensor failure test cases. This paper discusses the design of the sensor validation and supporting modules developed at LeRC and reviews results obtained from initial test cases

Dermanyssus gallinae in layer farms in Kosovo: a high risk for salmonella prevalence

Background The poultry red mite (PRM), Dermanyssus gallinae (D.g.) is a serious ectoparasitic pest of poultry and potential pathogen vector. The prevalence of D. g. and the prevalence of Salmonella spp. within mites on infested laying poultry farms were investigated in Kosovo. Findings In total, 14 populated layer farms located in the Southern Kosovo were assessed for D. g. presence. Another two farms in this region were investigated 6 months after depopulation. Investigated flocks were all maintained in cages, a common housing system in Kosovo. A total of eight farms were found to be infested with D. g. (50%) at varying levels, including the two depopulated farms. The detection of Salmonella spp. from D. g. was carried out using PCR. Out of the eight layer farms infested with D. g., Salmonella spp. was present in mites on three farms (37.5%). Conclusions This study confirms the high prevalence of D. g. in layer flocks in Kosovo and demonstrates the link between this mite and the presence of Salmonella spp. on infested farms