Performance documentation of the engineering model 30-cm diameter thruster

The results of extensive testing of two 30-cm ion thrusters which are virtually identical to the 900 series Engineering Model Thruster in an ongoing 15,000-hour life test are presented. Performance data for the nominal fullpower (2650 W) operating point; performance sensitivities to discharge voltage, discharge losses, accelerator voltage, and magnetic baffle current; and several power throttling techniques (maximum Isp, maximum thrust/power ratio, and two cases in between are included). Criteria for throttling are specified in terms of the screen power supply envelope, thruster operating limits, and control stability. In addition, reduced requirements for successful high voltage recycles are presented

An Assessment of Integrated Flywheel System Technology

The current state of the technology in flywheel storage systems and ancillary components, the technology in light of future requirements, and technology development needs to rectify these shortfalls were identified. Technology efforts conducted in Europe and in the United States were reviewed. Results of developments in composite material rotors, magnetic suspension systems, motor/generators and electronics, and system dynamics and control were presented. The technology issues for the various disciplines and technology enhancement scenarios are discussed. A summary of the workshop, and conclusions and recommendations are presented

Decentering Cognition

The neocortex figures importantly in human cognition, but it is not the only locus of cognitive activities or even at the top of a hierarchy of cognitive processing areas in the central nervous system. Moreover, the form of information processing employed in the neocortex is not representative of information processing elsewhere in the nervous system. In this paper, we articulate and argue against cortico-centrism in cognitive science, contending instead that the nervous system constitutes a heterarchical network of diverse types of information processing systems. To press this perspective, we examine neural information processing in both non-vertebrates and vertebrates, including examples of cognitive processing in the vertebrate hypothalamus and basal ganglia

A 1000 hour endurance test of a glass-coated accelerator grid on a 15-centimeter-diameter Kaufman thruster

Endurance test of glass coated accelerator grid on 15-centimeter-diameter Kaufman thruste

Model-Based Analysis of the Limiting Mechanisms in the Gas-Phase Oxidation of HCl Employing an Oxygen Depolarized Cathode

The electrochemical oxidation of HCl to Cl2 plays an important role in the production of polycarbonates and polyurethanes. Recently, the gas-phase oxidation of HCl proved to be significantly more efficient than the current state-of-the-art process based on the oxidation of hydrochloric acid. In experimental investigations of this gas-phase reactor, a limiting current can be observed that is so far not understood but impedes the overall reactor performance. In the present work, a nonisothermal multiphase agglomerate model is developed to investigate the underlying reasons for this limiting behavior in more detail. It is shown that the thermal management of the cell plays a significant role and that minor changes to its thermal resistance lead to the limiting behavior being caused by either flooding of the cathode or dehydration of the membrane and anode. An optimization of operational and structural parameters of the cell based on these insights leads to an increase in the limiting current by more than 90%. Interestingly, under these conditions a third phenomenon, the rate determining Tafel step in the microkinetic reaction mechanism of the HCl oxidation, limits the overall reactor performance. These insights harbor the potential for enormous energetic savings in this industrially highly relevant process

Structural analysis demonstration of constitutive and life models

The overall objective of this program is to demonstrate the applicability of NASA-developed advanced constitutive and life damage models for calculating cyclic structural response and crack initiation in selected components of reusable space propulsion systems. The computer model resulting from this program will enable the user to produce an accurate life prediction of hot gas path, life limiting components of propulsion systems such as the space shuttle main engine (SSME). Previously developed computer models addressing constitutive modeling and life damage will be combined in an advanced finite element analysis to generate a sophisticated baseline life prediction program. A material data base will be established for the constitutive and life models parametrically involving temperature, strain range, strain rate, mean strain/stress, and dwell time. The verified computer program will be used to accomplish the life predictions of three SSME critical components as evidence of the model functionality