Heat transfer in the tip region of a rotor blade simulator

The measurement of mass transfer from cavities is discussed with emphasis on the effect of cavity orientations relative to the main flow direction. A finite difference computation for turbulent air flow and heat transfer over a two-dimensional shrouded rectangular cavity is discussed

Dual purpose optical instrument capable of simultaneously acting as spectrometer and diffractometer

A dual purpose optical instrument is described capable of simultaneously acting as a spectrometer and diffractometer to respectively perform elemental and structural analysis of an unknown sample. The diffractometer portion of the instrument employs a modified form of Seeman-Bohlin focusing which involves providing a line source of X-rays, a sample, and a detector, all on the same focal circle. The spectrometer portion of the instrument employs a fixedly mounted X-ray energy detector mounted outside of the plane of the focal circle

Heat transfer in the tip region of a rotor blade simulator

In gas turbines, the blades of axial turbine stages rotate in close proximity to a stationary peripheral wall. Differential expansion of the turbine wheel, blades, and the shroud causes variations in the size of the clearance gap between blade tip and stationary shroud. The necessity to tolerate this differential thermal expansion dictates that the clearance gap cannot be eliminated altogether, despite accurate engine machining. Pressure differences between the pressure and suction sides of a blade drives a flow through the clearance gap. This flow, the tip leakage flow, is detrimental to engine performance. The primary detrimental effect of tip leakage flow is the reduction of turbine stage efficiency, and a second is the convective heat transfer associated with the flow. The surface area at the blade tip in contact with the hot working gas represents an additional thermal loading on the blade which, together with heat transfer to the suction and pressure side surface area, must be removed by the blade internal cooling flows. Experimental results concerned with the local heat transfer characteristics on all surfaces of shrouded, rectangular cavities are reported. A brief discussion of the mass transfer system used is given

Heat transfer in the tip region of a rotor blade simulator

The objective of this study of heat transfer in the tip region of a rotor blade simulator is to acquire, through experimental and computational approaches, improved understanding of the nature of the flow and convective heat transfer in the blade tip region. Such information should enable designers to make more accurate predictions of performance and durability, and should support the future development of improved blade tip cooling schemes

Comparing Secco Recitative Accompaniment by Contemporary Cellists and Cellists in the 19th Century: A Study of Social and Cultural Assumptions

This article documents the behavior of current professional continuo cellists who accompany secco recitatives, addressing such issues as instrumentation, seating plans, harmonic realization, rehearsal protocol, leadership roles, critical feedback and (self)-evaluation. It summarizes and analyses the results of a questionnaire launched in the Spring of 2020 and answered by 105 professional continuo playing cellists around the world. By comparing the accompaniment practice of current continuo cellists to the performance practice of cellists who accompanied secco recitatives in the late 18th and early 19th centuries, this analysis brings to light the cultural and sociological factors that influence our changing expectations about appropriate instrumental roles in secco recitative accompaniment

Nature\u27s Goodness: An Aristotelian Account

Neo-Aristotelians have made major headway in moral theory, and it is now commonplace to find philosophers defending the reality of goodness through a teleological analysis of human being. Whatever the merits of this approach, it has suffered from a lack of a sustained defense of its pre-modern metaphysical panorama: the Aristotelian conception of the human good gets traction only if its decidedly pre-modern and `robust\u27 philosophy of nature is defensible in its own right. In this dissertation, I aim to give a partial breakdown of the particular sort of metaphysical project that the Aristotelian moral theorist assumes, but does not always explicate. In particular, I aim to show how neo-Aristotelians rely on a particular view of substance that, while certainly challenging to contemporary naturalist construals of the same, is nevertheless defensible in its own right. Moreover, it might well be the case that even `liberal\u27 contemporary naturalist construals of `moral facts\u27 face difficulties that cannot be overcome; for they might only be able to countenance the less deflationary moral ontologies they desire by first assuming a view of substance that puts pressure on the entirety of the `modern\u27 project. The first part of this dissertation will focus on the ways that an Aristotelian nature is defensible. The second part will show in more detail how this pre-modern vision of reality helps to locate and in some cases even `solve\u27 certain metaethical conundrums. The goal is to show why an Aristotelian moral theory can offer a credible alternative to the usual `moral realist\u27 positions in contemporary metaethics, by offering not just a more plausible view of human goodness, but a more plausible view of nature as a whole

Algorithm based comparison between the integral method and harmonic analysis of the timing jitter of diode-based and solid-state pulsed laser sources

AbstractA comparison between two methods of timing jitter calculation is presented. The integral method utilizes spectral area of the single side-band (SSB) phase noise spectrum to calculate root mean square (rms) timing jitter. In contrast the harmonic analysis exploits the uppermost noise power in high harmonics to retrieve timing fluctuation. The results obtained show that a consistent timing jitter of 1.2ps is found by the integral method and harmonic analysis in gain-switched laser diodes with an external cavity scheme. A comparison of the two approaches in noise measurement of a diode-pumped Yb:KY(WO4)2 passively mode-locked laser is also shown in which both techniques give 2ps rms timing jitter

Comment on "Mechanical analog of temperature for the description of force distribution in static granular packings"

It has been proposed by Ngan [Phys. Rev. E 68, 011301 (2003)] that the granular contact force distribution may be analytically derived by minimizing the analog of a thermodynamic free energy, in this case consisting of the total potential energy stored in the compressed contacts minus a particular form of entropy weighted by a parameter. The parameter is identified as a mechanical temperature. I argue that the particular form of entropy cannot be correct and as a result the proposed method produces increasingly errant results for increasing grain rigidity. This trend is evidenced in Ngan's published results and in other numerical simulations and experiments.Comment: 4 pages, 1 figure, minor editorial correction