972 research outputs found
Development of the mathematical model of catalytic cracking: identification of hydrocarbon of the vacuum distillate usin chromatomass- spectrometry
Information about composition of catalytic cracking raw materials and products is required fordevelopment of mathematical model of catalytic cracking. The results of laboratory investigation ondetermination of the composition of catalytic cracking vacuum distillate were performed in this work. Groupcomposition of the catalytic cracking raw materials was defined using liquid-adsorption chromatographicseparation on silica gel. Paraffin-naphthenic and aromatic fraction was indefined by chromato-massspectrometry
Corrigendum
The European Vitis Database (www.eu-vitis.de) - a technical innovation through an online uploading and interactive modification systemVitis 51 (2), 79-85 (2012
Propulsion IVHM Technology Experiment
The Propulsion IVHM Technology Experiment (PITEX) successfully demonstrated real-time fault detection and isolation of a virtual reusable launch vehicle (RLV) main propulsion system (MPS). Specifically, the PITEX research project developed and applied a model-based diagnostic system for the MPS of the X-34 RLV, a space-launch technology demonstrator. The demonstration was simulation-based using detailed models of the propulsion subsystem to generate nominal and failure scenarios during captive carry, which is the most safety-critical portion of the X-34 flight. Since no system-level testing of the X-34 Main Propulsion System (MPS) was performed, these simulated data were used to verify and validate the software system. Advanced diagnostic and signal processing algorithms were developed and tested in real time on flight-like hardware. In an attempt to expose potential performance problems, the PITEX diagnostic system was subjected to numerous realistic effects in the simulated data including noise, sensor resolution, command/valve talkback information, and nominal build variations. In all cases, the PITEX system performed as required. The research demonstrated potential benefits of model-based diagnostics, defined performance metrics required to evaluate the diagnostic system, and studied the impact of real-world challenges encountered when monitoring propulsion subsystems
Propulsion Health Management System Development for Affordable and Reliable Operation of Space Exploration Systems
The constraints of future Exploration Missions will require unique integrated system health management capabilities throughout the mission. An ambitious launch schedule, human-rating requirements, long quiescent periods, limited human access for repair or replacement, and long communication delays, all require an integrated approach to health management that can span distinct, yet interdependent vehicle subsystems, anticipate failure states, provide autonomous remediation and support the Exploration Mission from beginning to end. Propulsion is a critical part of any space exploration mission, and monitoring the health of the propulsion system is an integral part of assuring mission safety and success. Health management is a somewhat ubiquitous technology that encompasses a large spectrum of physical components and logical processes. For this reason, it is essential to develop a systematic plan for propulsion health management system development. This paper provides a high-level perspective of propulsion health management systems, and describes a logical approach for the future planning and early development that are crucial to planned space exploration programs. It also presents an overall approach, or roadmap, for propulsion health management system development and a discussion of the associated roadblocks and challenges
Comparison of Simulator Wear Measured by Gravimetric vs Optical Surface Methods for Two Million Cycles
Understanding wear mechanisms are key for better implants
Critical to the success of the simulation
Small amount of metal wear can have catastrophic effects in the patient such as heavy metal poisoning or deterioration of the bone/implant interface leading to implant failure
Difficult to measure in heavy hard-on-hard implants (metal-on-metal or ceramic-on-ceramic)
May have only fractions of a milligram of wear on a 200 g component
At the limit of detection of even high-end balances when the component is 200 g and the change in weight is on the order of 0.000 1 grams
Here we compare the standard gravimetric wear estimate with
A non-contact 3D optical profiling method at each weighing stop
A coordinate measuring machine (CMM) at the beginning and end of the ru
Post-synthetic modification of epitaxially grown, highly oriented functionalized MOF thin films
Application of Diagnostic Analysis Tools to the Ares I Thrust Vector Control System
The NASA Ares I Crew Launch Vehicle is being designed to support missions to the International Space Station (ISS), to the Moon, and beyond. The Ares I is undergoing design and development utilizing commercial-off-the-shelf tools and hardware when applicable, along with cutting edge launch technologies and state-of-the-art design and development. In support of the vehicle s design and development, the Ares Functional Fault Analysis group was tasked to develop an Ares Vehicle Diagnostic Model (AVDM) and to demonstrate the capability of that model to support failure-related analyses and design integration. One important component of the AVDM is the Upper Stage (US) Thrust Vector Control (TVC) diagnostic model-a representation of the failure space of the US TVC subsystem. This paper first presents an overview of the AVDM, its development approach, and the software used to implement the model and conduct diagnostic analysis. It then uses the US TVC diagnostic model to illustrate details of the development, implementation, analysis, and verification processes. Finally, the paper describes how the AVDM model can impact both design and ground operations, and how some of these impacts are being realized during discussions of US TVC diagnostic analyses with US TVC designers
Double-arm three-dimensional ion imaging apparatus for the study of ion pair channels in resonance enhanced multiphoton ionization
Assessment of Neglect Dyslexia with Functional Materials
Spatial neglect is a neurocognitive disorder, affecting perception, representation, and/or motor planning. Neglect dyslexia in spatial neglect after right hemisphere damage (RHD) may co-occur with, or be dissociated from, other spatial neglect signs (Arduino, Daini, & Silveri, 2005; Lee et al., 2009; Vallar, Burani, & Arduino, 2010). Previous neglect dyslexia research focused on word-level stimuli and reading errors, primarily identifying letter omissions and substitutions to the left of the word midpoint (Ellis, Flude, & Young, 1987). However, functional materials may be more challenging to read (greater spatial extent of sentences and paragraphs, versus words). Although experimental studies that focus on reading at the single-word level may ask interesting theoretical questions regarding the sources of errors in the reading stages and systems, it is not often in the real-world that people read single words in isolation.
We hypothesized that assessment materials with ecological validity such as reading a menu and reading an article would be more reflective of the degree to which reading errors and neglect dyslexia was detected in individuals with RHD than assessments that contained only single words or short phrases, which are rarely read in isolation in everyday life
Parton distribution functions from nonlocal light-cone operators with definite twist
We introduce the chiral-even and chiral-odd quark distributions as forward
matrix elements of related bilocal quark operators with well-defined
(geometric) twist. Thereby, we achieve a Lorentz invariant classification of
these distributions which differ from the conventional ones by explicitly
taking into account the necessary trace terms. The relations between both kinds
of distribution functions are given and the mismatch between their different
definition of twist is discussed. Wandzura-Wilczek--like relations between the
conventional distributions (based on dynamical twist) are derived by means of
geometric twist distribution functions.Comment: 17 pages, REVTEX, Extended version, The Introduction has been
rewritten, Setion V "Wandzura-Wilczek--like relations" and App. B are added;
Sign errors are correcte
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