DEAN: A program for dynamic engine analysis

The Dynamic Engine Analysis program, DEAN, is a FORTRAN code implemented on the IBM/370 mainframe at NASA Lewis Research Center for digital simulation of turbofan engine dynamics. DEAN is an interactive program which allows the user to simulate engine subsystems as well as a full engine systems with relative ease. The nonlinear first order ordinary differential equations which define the engine model may be solved by one of four integration schemes, a second order Runge-Kutta, a fourth order Runge-Kutta, an Adams Predictor-Corrector, or Gear's method for still systems. The numerical data generated by the model equations are displayed at specified intervals between which the user may choose to modify various parameters affecting the model equations and transient execution. Following the transient run, versatile graphics capabilities allow close examination of the data. DEAN's modeling procedure and capabilities are demonstrated by generating a model of simple compressor rig

Method for predicting rotor free-wake positions and the resulting rotor blade airloads

Computer program has been designed and written to predict rotor free-wake positions and resulting rotor blade airloads without requiring time-consuming and tedious calculations. This program was written in FORTRAN IV for use on an IBM-360 computer

Microstructure-failure mode correlations in braided composites

Explication of the fracture processes of braided composites is needed for modeling their behavior. Described is a systematic exploration of the relationship between microstructure, loading mode, and micro-failure mechanisms in carbon/epoxy braided composites. The study involved compression and fracture toughness tests and optical and scanning electron fractography, including dynamic in-situ testing. Principal failure mechanisms of low sliding, buckling, and unstable crack growth are correlated to microstructural parameters and loading modes; these are used for defining those microstructural conditions which are strength limiting

Main rotor free wake geometry effects on blade air loads and response for helicopters in steady maneuvers. Volume 2: Program listings

A mathematical model and computer program was implemented to study the main rotor free wake geometry effects on helicopter rotor blade air loads and response in steady maneuvers. Volume 1 (NASA CR-2110) contains the theoretical formulation and analysis of results. Volume 2 contains the computer program listing

What Powers the Compact Radio Emission in Nearby Elliptical and S0 Galaxies?

Many nearby early-type (elliptical and S0) galaxies contain weak (milli-Jansky level) nuclear radio sources on scales a few hundred parsecs or less. The origin of the radio emission, however, has remained unclear, especially in volume-limited samples that select intrinsically less luminous galaxies. Both active galactic nuclei and nuclear star formation have been suggested as possible mechanisms for producing the radio emission. This paper utilizes optical spectroscopic information to address this issue. A substantial fraction of the early-type galaxies surveyed with the Very Large Array by Wrobel & Heeschen (1991) exhibits detectable optical emission lines in their nuclei down to very sensitive limits. Comparison of the observed radio continuum power with that expected from the thermal gas traced by the optical emission lines implies that the bulk of the radio emission is nonthermal. Both the incidence and the strength of optical line emission correlate with the radio power. At a fixed line luminosity, ellipticals have stronger radio cores than S0s. The relation between radio power and line emission observed in this sample is consistent with the low-luminosity extension of similar relations seen in classical radio galaxies and luminous Seyfert nuclei. A plausible interpretation of this result is that the weak nuclear sources in nearby early-type galaxies are the low-luminosity counterparts of more powerful AGNs. The spectroscopic evidence supports this picture. Most of the emission-line objects are optically classified as Seyfert nuclei or low-ionization nuclear emission-line regions (LINERs), the majority of which are likely to be accretion-powered sources.Comment: LaTex, 16 pages including embedded figures. Accepted for publication in the Astrophysical Journa

A Sensor Failure Simulator for Control System Reliability Studies

A real-time Sensor Failure Simulator (SFS) was designed and assembled for the Advanced Detection, Isolation, and Accommodation (ADIA) program. Various designs were considered. The design chosen features an IBM-PC/XT. The PC is used to drive analog circuitry for simulating sensor failures in real-time. A user defined scenario describes the failure simulation for each of the five incoming sensor signals. Capabilities exist for editing, saving, and retrieving the failure scenarios. The SFS has been tested closed-loop with the Controls Interface and Monitoring (CIM) unit, the ADIA control, and a real-time F100 hybrid simulation. From a productivity viewpoint, the menu driven user interface has proven to be efficient and easy to use. From a real-time viewpoint, the software controlling the simulation loop executes at greater than 100 cycles/sec

Photoactivation of trans diamine platinum complexes in aqueous solution and effect on reactivity towards nucleotides

We show that UVA irradiation (365 nm) of the Pt-IV complex trans,trans,trans-[(PtCl2)-Cl-IV(OH)(2)(dimethylamine) (isopropylamine)] (1), induces reduction to Pt-II photoproducts. For the mixed amine Pt-II complex, trans[(PtCl2)-Cl-II(isopropylamine)(methylamine)] (2), irradiation at 365 nm increases the rate and extent of hydrolysis, triggering the formation of diaqua species. Additionally, irradiation increases the extent of reaction of complex 2 with guanosine-5'-monophosphate and affords mainly the bis-adduct, while reactions with adenosine-5'-monophosphate and cytidine-5'-monophosphate give rise only to mono-nucleotide adducts. Density Functional Theory calculations have been used to obtain insights into the electronic structure of complexes 1 and 2, and their photophysical and photochemical properties. UVA-irradiation can contribute to enhanced cytotoxic effects of diamine platinum drugs with trans geometry

Classroom assessment and education: challenging the assumptions of socialisation and instrumentality

The opportunity offered by the Umea Symposium to probe the intersection of quality and assessment immediately brings into focus a wider issue – that of the quality of education which assessment aspires to support. Prompted by recent research into formative assessment in Scottish primary school contexts, the paper explores how formative assessment has become associated with an overly benign understanding of learning which misrecognises the possibility of undesirable learning and does not seem to address the inherently political nature of education. Having illuminated the potential inequities of formative assessment practices, the paper then asks what role formative assessment might play to support an understanding of education that is not simply about the transmission of traditional social norms, but also aspires to illuminate their social construction and their political nature

An experimental examination of the role of re-engineering in the management of software quality

This paper reports on the design and the results of a randomised, controlled experiment estimating the effect of predetermined changes in module complexity on the maintainability of different program versions seeded with equivalent logic errors. The experiment measures maintainability which is a defining sub-attribute of quality. The hypothesis "low module complexity results in high maintainability" is tested experimentally by monitoring and recording the time taken to identify and correct the seeded errors. Prior to the experiment programs are statically analysed to produce measurements of internal sub-attributes of the fundamental attribute of complexity. A first program version is modularised according to established rules giving a new version with a larger number of modules and with smaller individual module complexity. The results of this work can be used to design tools capable of providing an indicator, or factor, for re-engineering whereby a given program can be restructured in such a way that quality improvement can be quantified or at least estimated. As maintainability is a defining attribute of quality the insights gained can be further applied in understanding the underlying processes involved and ultimately lead to quality improvements