Unsteady three-dimensional simulation of VTOL upwash fountain turbulence

Numerical simulations of a planar turbulent wall jet and a planar VTOL upwash fountain were performed. These are three dimensional simulations which resolve large scale unsteady motions in the flows. The wall jet simulation shows good agreement with experimental data and is presented to verify the simulation methodology. Simulation of the upwash fountain predicts elevated shear stress and a half velocity width spreading rate of 33% which agrees well with experiment. Turbulence mechanisms which contribute to the enhanced spreading rate are examined

Complexity of the XY antiferromagnet at fixed magnetization

We prove that approximating the ground energy of the antiferromagnetic XY model on a simple graph at fixed magnetization (given as part of the instance specification) is QMA-complete. To show this, we strengthen a previous result by establishing QMA-completeness for approximating the ground energy of the Bose-Hubbard model on simple graphs. Using a connection between the XY and Bose-Hubbard models that we exploited in previous work, this establishes QMA-completeness of the XY model

Experimental rotordynamic coefficient results for honeycomb seals

Test results (leakage and rotordynamic coefficients) are presented for seven honeycomb-stator smooth-rotor seals. Tests were carried out with air at rotor speeds up to 16,000 cpm and supply pressures up to 8.2 bars. Test results for the seven seals are compared, and the most stable configuration is identified based on the whirl frequency ratio. Results from tests of a smooth-rotor/smooth-stator seal, a teeth-on-stator labyrinth seal, and the most stable honeycomb seal are compared

Records management capacity and compliance toolkits : a critical assessment.

This article seeks to present the results of a project that critically evaluated a series of toolkits for assessing records management capacity and/or compliance. These toolkits have been developed in different countries and sectors within the context of the e-environment and provide evidence of good corporate and information governance. Design/methodology/approach - A desk-based investigation of the tools was followed by an electronic Delphi with toolkit developers and performance measurement experts to develop a set of evaluation criteria. Different stakeholders then evaluated the toolkits against the criteria using cognitive walkthroughs and expert heuristic reviews. The results and the research process were reviewed via electronic discussion. Findings - Developed by recognised and highly respected organisations, three of the toolkits are software tools, whilst the fourth is a methodology. They are all underpinned by relevant national/international records management legislation, standards and good practice including, either implicitly or explicitly, ISO 15489. They all have strengths, complementing rather than competing with one another. They enable the involvement of other staff, thereby providing an opportunity for raising awareness of the importance of effective records management. Practical implications - These toolkits are potentially very powerful, flexible and of real value to organisations in managing their records. They can be used for a "quick and dirty" assessment of records management capacity or compliance as well as in-depth analysis. The most important criterion for selecting the appropriate one is to match the toolkit with the scenario. Originality/value - This paper aims to raise awareness of the range and nature of records management toolkits and their potential for varied use in practice to support more effective management of records

Annular honeycomb seals: Test results for leakage and rotordynamic coefficients; comparisons to labyrinth and smooth configurations

Test results are presented for leakage and rotordynamic coefficients for seven honeycomb seals. All seals have the same radius, length, and clearance; however, the cell depths and diameters are varied. Rotordynamic data, which are presented, consist of the direct and cross-coupled stiffness coefficients and the direct damping coefficients. The rotordynamic-coefficient data show a considerable sensitivity to changes in cell dimensions; however, no clear trends are identifiable. Comparisons of test data for the honeycomb seals with labyrinth and smooth annular seals show the honeycomb seal had the best sealing (minimum leakage) performance, followed in order by the labyrinth and smooth seals. For prerotated fluid entering the seal, in the direction of shaft rotation, the honeycomb seal has the best rotordynamic stability followed in order by the labyrinth and smooth. For no prerotation, or fluid prerotation against shaft rotation, the labyrinth seal has the best rotordynamic stability followed in order by the smooth and honeycomb seals

Dominant role of many-body effects on the carrier distribution function of quantum dot lasers

The effects of free-carrier-induced shift and broadening on the carrier distribution function are studied considering different extreme cases for carrier statistics (Fermi–Dirac and random carrier distributions) as well as quantum dot (QD) ensemble inhomogeneity and state separation using a Monte Carlo model. Using this model, we show that the dominant factor determining the carrier distribution function is the free carrier effects and not the choice of carrier statistics. By using empirical values of the free-carrier-induced shift and broadening, good agreement is obtained with experimental data of QD materials obtained under electrical injection for both extreme cases of carrier statistics

Frank Ferko\u27s The Hildegard motets: a conductor\u27s preparatory guide

The music of Hildegard of Bingen has received much attention from Frank Ferko in the past decade, but his interest in the medieval mystic has not stopped there. At the heart of his intense affection for her music are the wonderful visions she expressed through this particular medium, but also through her vivid, and at times, abstruse, poetry. His Hildegard Organ Cycle (1996), a set of ten symphonic meditations on the visions from De operatione Det, and his Missa O Ecclesia: Communion (1999), are both examples of instrumental works that bear direct reference to the twelfth-century abbess\u27 writings. The Hildegard Motets (1996), choral works of varying voicings, are set to the original Latin texts from Hildegards opus of over seventy sacred poems entitled Symphonia celestium revelationum. They comprise a cycle of nine choral motets for various seasons in the Christian liturgical calendar. The monograph is divided into three chapters, the first being an examination of the life and works of Hildegard of Bingen; the second a biographical presentation on the composer, Frank Ferko, and; the third a study of the nine Hildegard motets. The latter chapter has been presented as a conductor\u27s preparatory study, and will examine each motet in detail, including the following aspects: relevant background information, discussion of the original poems upon which the works are based, and an analysis and discussion of the most prominent stylistic elements found in the scores. The Hildegard Motets have been recorded by the American Repertory Singers, directed by Leo Nester, and released on ARSIS CD 102

Universal quantum computation by discontinuous quantum walk

Quantum walks are the quantum-mechanical analog of random walks, in which a quantum `walker' evolves between initial and final states by traversing the edges of a graph, either in discrete steps from node to node or via continuous evolution under the Hamiltonian furnished by the adjacency matrix of the graph. We present a hybrid scheme for universal quantum computation in which a quantum walker takes discrete steps of continuous evolution. This `discontinuous' quantum walk employs perfect quantum state transfer between two nodes of specific subgraphs chosen to implement a universal gate set, thereby ensuring unitary evolution without requiring the introduction of an ancillary coin space. The run time is linear in the number of simulated qubits and gates. The scheme allows multiple runs of the algorithm to be executed almost simultaneously by starting walkers one timestep apart.Comment: 7 pages, revte

Studies relating to Polyunsaturated Fatty Acid (PUFA) Supplementation and Fertility in Cattle

End of project reportReproductive inefficiency has a significant impact on the economic performance of both dairy and beef herds, particularly in seasonal calving systems. Nutrition plays a fundamental role in reproduction. Furthermore, there is emerging evidence that supplemental dietary polyunsaturated fatty acids (PUFA) may increase cow fertility independent of their role as energy substrates. A number of studies have reported enhanced reproductive performance in dairy cows following dietary supplementation with sources of n-3 PUFA. However the possible mechanisms involved have not been identified and there is some inconsistency in the published literature on this topic. The objective of the research reported was to conduct a holistic examination of the effects of dietary long-chain n-3 PUFA supplementation on metabolic and reproductive responses in cattle. Such information is essential for the appropriate formulation of diets to enhance cow reproductive performance and in particular embryo survival