Estimation of cavitation limits from local head loss coefficient

Cavitation effects in valves and other sudden transitions in water distribution systems are studied as their better understanding and quantification is needed for design and analysis purposes and for predicting and controlling their operation. Two dimensionless coefficients are used to characterize and verify local effects under cavitating flow conditions: the coefficient of local head losses and the minimum value of the cavitation number. In principle, both coefficients must be determined experimentally, but a semianalytical relationship between them is here proposed so that if one of them is known, its value can be used to estimate the corresponding value of the other one. This relationship is experimentally contrasted by measuring head losses and flow rates. It is also shown that cavitation number values, called cavitation limits, such as the critical cavitation limit, can be related in a simple but practical way with the mentioned minimum cavitation number and with a given pressure fluctuation level. Head losses under conditions of cavitation in sharp-edged orifices and valves are predicted for changes in upstream and downstream boundary conditions. An experimental determination of the coefficient of local head losses and the minimum value of the cavitation number is not dependent on the boundary conditions even if vapor cavity extends far enough to reach a downstream pressure tap. Also, the effects of cavitation and displacement of moving parts of valves on head losses can be split. A relatively simple formulation for local head losses including cavitation influence is presented. It can be incorporated to water distribution analysis models to improve their results when cavitation occurs. Likewise, it can also be used to elaborate information about validity limits of head losses in valves and other sudden transitions and to interpret the results of head loss tests

Muscle memory: The inimitable feel of the record

Muscle Memory is a new record I have made in collaboration with pianist Matthew Bourne (playing Memorymoog), and trumpeter Graham South. Comprising two composed sound pieces, it was released on vinyl in 2017. The pieces are structured around recordings made in the houses of each collaborator, documenting the act of listening to records. The compositions include conversation between composer and collaborators, samples of music from records heard/discussed, improvised instrumental sections, and electronically manipulated materials. Muscle Memory has since been presented to a number of audiences attending ‘living-room’ listening sessions - held in small, intimate and domestic spaces across the UK. Participative listening of this type is understood through Simon Frith and Christopher Small as an inclusive, collaborative, compositional action. The tactility (Mike D’Errico) and ‘objectness’ (David Grubbs) of records is also of importance. This text is a document of that listening experience

Application of advanced technologies to small, short-haul transport aircraft

The performance and economic benefits available by incorporation of advanced technologies into the small, short haul air transport were assessed. Low cost structure and advanced composite material, advanced turboprop engines and new propellers, advanced high lift systems and active controls; and alternate aircraft configurations with aft mounted engines were investigated. Improvements in fuel consumed and aircraft economics (acquisition cost and direct operating cost) are available by incorporating selected advanced technologies into the small, short haul aircraft

Fuel conservation merits of advanced turboprop transport aircraft

The advantages of a propfan powered aircraft for the commercial air transportation system were assessed by the comparison with an equivalent turbofan transport. Comparisons were accomplished on the basis of fuel utilization and operating costs, as well as aircraft weight and size. Advantages of the propfan aircraft, concerning fuel utilization and operating costs, were accomplished by considering: (1) incorporation of propfan performance and acoustic data; (2) revised mission profiles (longer design range and reduction in; and cruise speed) (3) utilization of alternate and advanced technology engines

Space station functional relationships analysis

A systems engineering process is developed to assist Space Station designers to understand the underlying operational system of the facility so that it can be physically arranged and configured to support crew productivity. The study analyzes the operational system proposed for the Space Station in terms of mission functions, crew activities, and functional relationships in order to develop a quantitative model for evaluation of interior layouts, configuration, and traffic analysis for any Station configuration. Development of the model involved identification of crew functions, required support equipment, criteria of assessing functional relationships, and tools for analyzing functional relationship matrices, as well as analyses of crew transition frequency, sequential dependencies, support equipment requirements, potential for noise interference, need for privacy, and overall compatability of functions. The model can be used for analyzing crew functions for the Initial Operating Capability of the Station and for detecting relationships among these functions. Note: This process (FRA) was used during Phase B design studies to test optional layouts of the Space Station habitat module. The process is now being automated as a computer model for use in layout testing of the Space Station laboratory modules during Phase C

Valuing life detection missions

Recent discoveries imply that Early Mars was habitable for life-as-we-know-it; that Enceladus might be habitable; and that many stars have Earth-sized exoplanets whose insolation favors surface liquid water. These exciting discoveries make it more likely that spacecraft now under construction - Mars 2020, ExoMars rover, JWST, Europa Clipper - will find habitable, or formerly habitable, environments. Did these environments see life? Given finite resources (\$10bn/decade for the US ), how could we best test the hypothesis of a second origin of life? Here, we first state the case for and against flying life detection missions soon. Next, we assume that life detection missions will happen soon, and propose a framework for comparing the value of different life detection missions: Scientific value = (Reach x grasp x certainty x payoff) / \$ After discussing each term in this framework, we conclude that scientific value is maximized if life detection missions are flown as hypothesis tests. With hypothesis testing, even a nondetection is scientifically valuable.Comment: Accepted by "Astrobiology.

Duality Unresolved and Darwinian Dilemmas

By using Sharon Street’s Darwinian Dilemma, Katarzyna de Lazari-Radek and Peter Singer attempt to show that Sidgwick’s duality of practical reason, whereby an agent has equal reason to act in their own interests or act impartially for the benefit of all, is not actually a duality, rather, reasons for action are solely impartial due to the unreliability of intuitions favoring self-interested behavior. My contention is that the author’s fail to accomplish their goal. To show this, I argue that the authors are inconsistent, that Singer has previously provided an account of impartiality that makes it just as unreliable on the same grounds as self-interested tendencies. By showing that the authors fail to address the actual target of Street’s dilemma, their argument and conclusion are overstated and that Sidgwick’s duality remains unresolved

Jeff Tullis, Double Bass

Mélodie from Orfeo ed Euridice / Christoph Willibald Gluck; arr. Tullis; Pièces en concert / Francois Couperin; Elegy No. 1 / Giovanni Bottesini; Deux pièces pour contrebasse et piano / Reinhold Glièr

Reynolds-Averaged Navier-Stokes CFD Simulation of High-Speed Boundary Layers

This paper presents an investigation of Reynolds-averaged Navier-Stokes (RANS) turbulence models used in computational fluid dynamics (CFD) simulations of boundary layer flow and heat transfer in high Mach number flows. This study evaluates an industry standard RANS turbulence model (k-omega SST) and a recently proposed modification to that model (Danis and Durbin [1]), and quantifies the accuracy for predicting high Mach number boundary layer flow. The test cases were previously documented by Duan et al. (2018), who used direct numerical simulation (DNS) to calculate boundary layer flow of an ideal gas over a flat plate at freestream Mach numbers ranging from 2 to 14 and wall to recovery temperature ratios of 0.18 to 1. Boundary layer profiles were evaluated at two streamwise locations, one where the boundary layer height matched the DNS data and the second where the wall shear stress matched DNS data. Results show that the accuracy of RANS models degrades for high-speed regimes compared to incompressible or subsonic flow but that the compressibility correction factor [1] improves the results for some of the test cases

Duality Unresolved and Darwinian Dilemmas

By using Sharon Street’s Darwinian Dilemma, Katarzyna de Lazari-Radek and Peter Singer attempt to show that Sidgwick’s duality of practical reason, whereby an agent has equal reason to act in their own interests or act impartially for the benefit of all, is not actually a duality, rather, reasons for action are solely impartial due to the unreliability of intuitions favoring self-interested behavior. My contention is that the author’s fail to accomplish their goal. To show this, I argue that the authors are inconsistent, that Singer has previously provided an account of impartiality that makes it just as unreliable on the same grounds as self-interested tendencies. By showing that the authors fail to address the actual target of Street’s dilemma, their argument and conclusion are overstated and that Sidgwick’s duality remains unresolved