Hot section viewing system

This report covers the development and testing of a prototype combustor viewing system. The system allows one to see and record images from the inside of an operating gas turbine combustor. The program proceeded through planned phases of conceptual design, preliminary testing to resolve problem areas, prototype design and fabrication, and rig testing. Successful tests were completed with the viewing system in the laboratory, in a high pressure combustor rig, and on a Pratt and Whitney PW20307 jet engine. Both film and video recordings were made during the tests. Digital image analysis techniques were used to enhance images and bring out special effects. The use of pulsed laser illumination was also demonstrated as a means for observing liner surfaces in the presence of luminous flame

Study of resonance light scattering for remote optical probing

Enhanced scattering and fluorescence processes in the visible and UV were investigated which will enable improved remote measurements of gas properties. The theoretical relationship between scattering and fluorescence from an isolated molecule in the approach to resonance is examined through analysis of the time dependence of re-emitted light following excitation of pulsed incident light. Quantitative estimates are developed for the relative and absolute intensities of fluorescence and resonance scattering. New results are obtained for depolarization of scattering excited by light at wavelengths within a dissociative continuum. The experimental work was performed in two separate facilities. One of these utilizes argon and krypton lasers, single moded by a tilted etalon, and a 3/4 meter double monochromator. This facility was used to determine properties of the re-emission from NO2, I2 and O3 excited by visible light. The second facility involves a narrow-line dye laser, and a 3/4 meter single monochromator. The dye laser produces pulsed light with 5 nsec pulse duration and 0.005 nm spectral width

SO2 Spectroscopy with A Tunable UV Laser

A portion of the fluorescence spectrum of SO2 has been studied using a narrow wavelength doubled dye laser as the exciting source. One purpose of this study is to evaluate the use of SO2 resonance re-emission as a probe of SO2 in the atmosphere. When the SO2 is excited by light at 300.2 nm, for example, a strong reemission peak is observed which is Stokes-shifted from the incident light wavelength by the usual Raman shift (the VI symmetric vibration frequency 1150.5/cm ). The intensity of this peak is sensitive to small changes (.01 nm) in the incident wavelength. Measurements of the N2 quenching and self quenching of this re-emission have been obtained. Preliminary analysis of this data indicates that the quenching is weak but not negligible. The dye laser in our system is pumped by a pulsed N2 laser. Tuning 'and spectral narrowing are accomplished using a telescope-echelle grating combination. In a high power configuration the resulting pulses have a spectral width of about 5 x 10(exp -3) nm and a time duration of about 6 nsec. The echelle grating is rotated by a digital stepping motor, such that each step shifts the wavelength by 6 x 10(exp -4) nm. In addition to the tunable, narrow wavelength uv source and spectral analysis of the consequent re-emission, the system also provides time resolution of the re-emitted light to 6 nsec resolution. This capability is being used to study the lifetime of low pressure S02 fluorescence at different wavelengths and pressures

Advanced high temperature static strain sensor development

An examination was made into various techniques to be used to measure static strain in gas turbine liners at temperatures up to 1150 K (1600 F). The methods evaluated included thin film and wire resistive devices, optical fibers, surface acoustic waves, the laser speckle technique with a heterodyne readout, optical surface image and reflective approaches and capacitive devices. A preliminary experimental program to develop a thin film capacitive device was dropped because calculations showed that it would be too sensitive to thermal gradients. In a final evaluation program, the laser speckle technique appeared to work well up to 1150 K when it was used through a relatively stagnant air path. The surface guided acoustic wave approach appeared to be interesting but to require too much development effort for the funds available. Efforts to develop a FeCrAl resistive strain gage system were only partially successful and this part of the effort was finally reduced to a characterization study of the properties of the 25 micron diameter FeCrAl (Kanthal A-1) wire. It was concluded that this particular alloy was not suitable for use as the resistive element in a strain gage above about 1000 K

The language codes of ISO 639: A premature, ultimately unobtainable, and possibly damaging standardization

009 Stephen Morey, Mark W. Post and Victor Friedman The language codes of ISO 639: A premature and possibly unobtainable standardization ISO 639 is an ambitious attempt to standardize and organize various types of references to the languages of the world. It is designed to be fully comprehensive and permanent; as such, it promises to greatly enhance the precision and reliability with which language materials can be archived, catalogued, and referenced in the literature, as well as the ease and precision with which such materials and references can be processed by machines and effectively located via search queries. There are, however, a number of serious problems with several components of ISO 639 as they are currently conceived. At a minimum, these are: (1) use of both The Ethnologue as the basis for ISO 639-3’s “three-letter codes” and of SIL as its registration authority is problematic for a number of reasons (2) in-principle “arbitrary” (but in fact not arbitrary) “mnemonic” labels of ISO 639-3 have the potential to enshrine offensive designations for language communities, and in fact currently do so (3) decision-making processes in ISO 639-3 are currently excessively centralized and privilege the views of a minority of the linguistics community (4) the in-principle “permanency” of language codes such as those of ISO 639-3 is fundamentally incompatible with the nature of human languages, which are demonstrably impermanent (5) the structure of ISO 639-3 has a serious potential to be misunderstood, misused, and in fact abused by decision-making bodies (such as arms of government in various political contexts) (6) ISO 639-5, which attempts to catalogue the genetic affiliations of the world’s languages, is highly premature, since there is nothing approaching agreement among specialists in a great number of cases (7) ISO 639-6, which attempts to catalogue language variation, is in principle impossible, unless it aims to extend to an analysis of the language use of every human being on Earth, living or dead On the basis of these observations, which we will illustrate by means of three detailed “case studies” from the Eastern Himalaya, the Burmese/Indian border region, and the Balkan region, we will argue that ISO 639 must be substantially re-conceived and re-organized before it can be supported by linguists. The language codes of ISO 639: A premature and possibly unobtainable standardization. ISO 639 is an ambitious attempt to standardize and organize various types of references to the languages of the world. It is designed to be fully comprehensive and permanent; as such, it promises to greatly enhance the precision and reliability with which language materials can be archived, catalogued, and referenced in the literature, as well as the ease and precision with which such materials and references can be processed by machines and effectively located via search queries. There are, however, a number of serious problems with several components of ISO 639 as they are currently conceived. At a minimum, these are: (1) use of both The Ethnologue as the basis for ISO 639-3’s “three-letter codes” and of SIL as its registration authority is problematic for a number of reasons (2) in-principle “arbitrary” (but in fact not arbitrary) “mnemonic” labels of ISO 639-3 have the potential to enshrine offensive designations for language communities, and in fact currently do so (3) decision-making processes in ISO 639-3 are currently excessively centralized and privilege the views of a minority of the linguistics community (4) the in-principle “permanency” of language codes such as those of ISO 639-3 is fundamentally incompatible with the nature of human languages, which are demonstrably impermanent (5) the structure of ISO 639-3 has a serious potential to be misunderstood, misused, and in fact abused by decision-making bodies (such as arms of government in various political contexts) (6) ISO 639-5, which attempts to catalogue the genetic affiliations of the world’s languages, is highly premature, since there is nothing approaching agreement among specialists in a great number of cases (7) ISO 639-6, which attempts to catalogue language variation, is in principle impossible, unless it aims to extend to an analysis of the language use of every human being on Earth, living or dead On the basis of these observations, which we will illustrate by means of three detailed “case studies” from the Eastern Himalaya, the Burmese/Indian border region, and the Balkan region, we will argue that ISO 639 must be substantially re-conceived and re-organized before it can be supported by linguists

Criteria for Optimum Mixture - Ratio Distribution Using Several Types of Impinging-Stream Injector Elements

Empirical correlations are given relating the mixture-ratio distributions produced by various configurations of impinging-stream injectors and the ratios of density, velocity, and orifice cross-sectional area of the two fluids being mixed. Injector-element designs studied are two-on-one, two-on-two, and four-on-one

Antiferromagnetic and Orbital Ordering on a Diamond Lattice Near Quantum Criticality

We present neutron scattering measurements on powder samples of the spinel FeSc2S4 that reveal a previously unobserved magnetic ordering transition occurring at 11.8(2)~K. Magnetic ordering occurs subsequent to a subtle cubic-to-tetragonal structural transition which distorts Fe coordinating sulfur tetrahedra lifting the orbital degeneracy. The application of 1~GPa hydrostatic pressure appears to destabilize this N\'eel state, reducing the transition temperature to 8.6(8)~K and redistributing magnetic spectral weight to higher energies. The relative magnitudes of ordered $\langle m \rangle^2\!=\!3.1(2)$ and fluctuating moments $\langle \delta m \rangle^2\!=\!13(1)$ show that the magnetically ordered ground state of FeSc2S4 is drastically renormalized and in proximity to criticality.Comment: 16 pages, 12 figure

Testing Order Constraints: Qualitative Differences Between Bayes Factors and Normalized Maximum Likelihood

We compared Bayes factors to normalized maximum likelihood for the simple case of selecting between an order-constrained versus a full binomial model. This comparison revealed two qualitative differences in testing order constraints regarding data dependence and model preference