Mass transfer from a circular cylinder: Effects of flow unsteadiness and slight nonuniformities

Experiments were performed to determine the effect of periodic variations in the angle of the flow incident to a turbine blade on its leading edge heat load. To model this situation, measurements were made on a circular cylinder oscillating rotationally in a uniform steady flow. A naphthalene mass transfer technique was developed and used in the experiments and heat transfer rates are inferred from the results. The investigation consisted of two parts. In the first, a stationary cylinder was used and the transfer rate was measured for Re = 75,000 to 110,000 and turbulence levels from .34 percent to 4.9 percent. Comparisons with both theory and the results of others demonstrate that the accuracy and repeatability of the developed mass transfer technique is about + or - 2 percent, a large improvement over similar methods. In the second part identical flow conditions were used but the cylinder was oscillated. A Strouhal number range from .0071 to .1406 was covered. Comparisons of the unsteady and steady results indicate that the magnitude of the effect of oscillation is small and dependent on the incident turbulence conditions

Rydberg-Rydberg interaction profile from the excitation dynamics of ultracold atoms in lattices

We propose a method for the determination of the interaction potential of Rydberg atoms. Specifically, we consider a laser-driven Rydberg gas confined in a one-dimensional lattice and demonstrate that the Rydberg atom number after a laser excitation cycle as a function of the laser detuning provides a measure for the Rydberg interaction coefficient. With the lattice spacing precisely known, the proposed scheme only relies on the measurement of the number of Rydberg atoms and thus circumvents the necessity to map the interaction potential by varying the interparticle separation.Comment: 4 pages, 2 figure

Ultralong-range polyatomic Rydberg molecules formed by a polar perturber

The internal electric field of a Rydberg atom electron can bind a polar molecule to form a giant ultralong-range stable polyatomic molecule. Such molecules not only share their properties with Rydberg atoms, they possess huge permanent electric dipole moments and in addition allow for coherent control of the polar molecule orientation. In this work, we include additional Rydberg manifolds which couple to the nearly degenerate set of Rydberg states employed in [S. T. Rittenhouse and H. R. Sadeghpour, Phys. Rev. Lett. 104, 243002 (2010)]. The coupling of a set of $(n+3)s$ Rydberg states with the $n(l>2)$ nearly degenerate Rydberg manifolds in alkali metal atoms leads to pronounced avoided crossings in the Born-Oppenheimer potentials. Ultimately, these avoided crossings enable the formation of the giant polyatomic Rydberg molecules with standard two-photon laser photoassociation techniques.Comment: 7 pages, 4 figure

Spectral properties of finite laser-driven lattices of ultracold Rydberg atoms

We investigate the spectral properties of a finite laser-driven lattice of ultracold Rydberg atoms exploiting the dipole blockade effect in the frozen Rydberg gas regime. Uniform one-dimensional lattices as well as lattices with variable spacings are considered. In the case of a weak laser coupling, we find a multitude of many-body Rydberg states with well-defined excitation properties which are adiabatically accessible starting from the ground state. A comprehensive analysis of the degeneracies of the spectrum as well as of the single and pair excitations numbers of the eigenstates is performed. In the strong laser regime, analytical solutions for the pseudo-fermionic eigenmodes are derived. Perturbative energy corrections for this approximative approach are provided.Comment: 17 pages, 12 figure

Is the LMA solar-neutrino solution ruled out by SN1987A data?

The development of new supernova neutrino detectors relies on the expected hard energy spectrum of the nu_mu and nu_tau emitted in the supernova. We show that SN1987A was sensitive to the large mixing angle (LMA) and "just so" solution to the solar neutrino problem. We review the previous analysis of the SN1987A data and propose a new analysis. The results of this analysis strongly disfavor the LMA solution, provided the nu_mu and nu_tau are hard as predictedComment: 4 pages; 6 figures. Presented at the Europhysics Neutrino Oscillation Workshop, NOW 2000 (EPS, Lecce, Italy, Sept. 9-16, 2000) and to be published in Nucl. Phys. B (PS) (North Holland, Amsterdam, 2001

A Role for Management Accountants in Best Practice Benchmarking

Best practice benchmarking (benchmarking for short) generally refers to the pursuit by organisations of enhanced performance by learning from the successful practices of others. Comparisons of processes which contribute to strategic success are made with other parts of the same organisation; competitors; or organisations operating comparable processes in a context which is in some way relevant. Benchmarking continues to grow in popularity in both private and public sector organisations – but does it always produce the desired outcomes? Although spectacular gains from benchmarking are claimed particularly in practitioner literature, there is also growing evidence of disappointment with the effectiveness of benchmarking. It can be very time consuming to undertake and manage, and ensuring that sharing information with competitors is to the mutual advantage of partner organisations is difficult. With this in mind, it is important to recognise that management accountants play pivotal roles at organisational interfaces and therefore could play a (more) significant part in successful benchmarking activities. This paper will report on an ongoing research project at the Open University Business School, funded by the Chartered Institute of Management Accountants, aimed at understanding, in depth, the processes which are undertaken by Management Accountants, in the name of benchmarking. The project team are using postal questionnaires and case studies to identify the features of successful benchmarking practice, and the characteristics of benchmarking organisations or benchmarking processes which are considered to be problematic. This research centres on an extensive survey of Management Accountants. This research has begun to identify the contribution which Management Accountants can make to successful benchmarking and the factors which have led organisations to abandon benchmarking activities. This study is also facilitating better understanding of the relationship between organisational size and level of benchmarking activity, the impact of benchmarking clubs, and the perceived costs and benefits of benchmarking to stakeholders. The final phase 3 of this research will focus on providing innovative ways to make the findings available to management accounting practitioners

One-dimensional Rydberg Gas in a Magnetoelectric Trap

We study the quantum properties of Rydberg atoms in a magnetic Ioffe-Pritchard trap which is superimposed by a homogeneous electric field. Trapped Rydberg atoms can be created in long-lived electronic states exhibiting a permanent electric dipole moment of several hundred Debye. The resulting dipole-dipole interaction in conjunction with the radial confinement is demonstrated to give rise to an effectively one-dimensional ultracold Rydberg gas with a macroscopic interparticle distance. We derive analytical expressions for the electric dipole moment and the critical linear density of Rydberg atoms.Comment: 4 pages, 2 figure