Improved design of item in high speed rotating machinery

Greater centrifugal radial growth of the preimpeller hub with respect to the impeller and nut at operating speed alleviates clamping and alignment problems in high speed rotating machinery. Design results in axial tightness and radial piloting of the preimpeller

Firm corruption in the presence of an auditor

This paper develops a framework to explore firm corruption taking account of interaction with an auditor. The basic idea is that an auditor can provide auditing and other (consultancy) services. The extent of the other services depends on firm profitability. Hence auditor profitability can increase with firm corruption that may provide an incentive to collude in corrupt practices. This basic idea is developed using a game theoretic framework. It is shown that a multiplicity of equilibria exist from stable corruption, through auditor controlled corruption, via multiple equilibria to honesty on behalf of both actors. Following the development of the model various policy options are highlighted that show the difficulty of completely removing corrupt practices

Attractions between charged colloids at water interfaces

The effective potential between charged colloids trapped at water interfaces is analyzed. It consists of a repulsive electrostatic and an attractive capillary part which asymptotically both show dipole--like behavior. For sufficiently large colloid charges, the capillary attraction dominates at large separations. The total effective potential exhibits a minimum at intermediate separations if the Debye screening length of water and the colloid radius are of comparable size.Comment: 8 pages, 1 figure, revised version (one paragraph added) accepted in JPC

Aerodynamic and directional acoustic performance of a scoop inlet

Aerodynamic and directional acoustic performances of a scoop inlet were studied. The scoop inlet is designed with a portion of the lower cowling extended forward to direct upward any noise that is propagating out the front of the engine toward the ground. The tests were conducted in an anechoic wind tunnel facility at free stream velocities of 0, 18, 41, and 61 m/sec and angles of attack from -10 deg to 120 deg. Inlet throat Mach number was varied from 0.30 to 0.75. Aerodynamically, at a free stream velocity of 41 m/sec, the design throat Mach number (0.63), and an angle of attack of 50 deg, the scoop inlet total pressure recovery was 0.989 and the total pressure distortion was 0.15. The angles of attack where flow separation occurred with the scoop inlet were higher than those for a conventional symmetric inlet. Acoustically, the scoop inlet provided a maximum noise reduction of 12 to 15 db below the inlet over the entire range of throat Mach number and angle of attack at a free-stream velocity of 41 m/sec

Fluid adsorption near an apex: Covariance between complete and critical wetting

Critical wetting is an elusive phenomenon for solid-fluid interfaces. Using interfacial models we show that the diverging length scales, which characterize complete wetting at an apex, precisely mimic critical wetting with the apex angle behaving as the contact angle. Transfer matrix, renormalization group (RG) and mean field analysis (MF) shows this covariance is obeyed in 2D, 3D and for long and short ranged forces. This connection should be experimentally accesible and provides a means of checking theoretical predictions for critical wetting.Comment: 4 pages, 1 figure, submitted to Physical Review Letter

Shock waves in capillary collapse of colloids: a model system for two--dimensional screened Newtonian gravity

Using Brownian dynamics simulations, density functional theory, and analytical perturbation theory we study the collapse of a patch of interfacially trapped, micrometer-sized colloidal particles, driven by long-ranged capillary attraction. This attraction {is formally analogous} to two--dimensional (2D) screened Newtonian gravity with the capillary length \hat{\lambda} as the screening length. Whereas the limit \hat{\lambda} \to \infty corresponds to the global collapse of a self--gravitating fluid, for finite \hat{\lambda} we predict theoretically and observe in simulations a ringlike density peak at the outer rim of a disclike patch, moving as an inbound shock wave. Possible experimental realizations are discussed.Comment: 5 pages, 3 figures, revised version with new Refs. added, matches version accepted for publication in PR

Quantifying Tensions between CMB and Distance Datasets in Models with Free Curvature or Lensing Amplitude

Recent measurements of the Cosmic Microwave Background (CMB) by the Planck Collaboration have produced arguably the most powerful observational evidence in support of the standard model of cosmology, i.e. the spatially flat $\Lambda$CDM paradigm. In this work, we perform model selection tests to examine whether the base CMB temperature and large scale polarization anisotropy data from Planck 2015 (P15) prefer any of eight commonly used one-parameter model extensions with respect to flat $\Lambda$CDM. We find a clear preference for models with free curvature, $\Omega_\mathrm{K}$, or free amplitude of the CMB lensing potential, $A_\mathrm{L}$. We also further develop statistical tools to measure tension between datasets. We use a Gaussianization scheme to compute tensions directly from the posterior samples using an entropy-based method, the surprise, as well as a calibrated evidence ratio presented here for the first time. We then proceed to investigate the consistency between the base P15~CMB data and six other CMB and distance datasets. In flat $\Lambda$CDM we find a $4.8\sigma$ tension between the base P15~CMB data and a distance ladder measurement, whereas the former are consistent with the other datasets. In the curved $\Lambda$CDM model we find significant tensions in most of the cases, arising from the well-known low power of the low-$\ell$ multipoles of the CMB data. In the flat $\Lambda$CDM $+A_\mathrm{L}$ model, however, all datasets are consistent with the base P15~CMB observations except for the CMB lensing measurement, which remains in significant tension. This tension is driven by the increased power of the CMB lensing potential derived from the base P15~CMB constraints in both models, pointing at either potentially unresolved systematic effects or the need for new physics beyond the standard flat $\Lambda$CDM model.Comment: 16 pages, 8 figures, 6 table

High Redshift Quasars and Star Formation in the Early Universe

In order to derive information on the star formation history in the early universe we observed 6 high-redshift (z=3.4) quasars in the near-infrared to measure the relative iron and \mgii emission strengths. A detailed comparison of the resulting spectra with those of low-redshift quasars show essentially the same FeII/MgII emission ratios and very similar continuum and line spectral properties, indicating a lack of evolution of the relative iron to magnesium abundance of the gas since z=3.4 in bright quasars. On the basis of current chemical evolution scenarios of galaxies, where magnesium is produced in massive stars ending in type II SNe, while iron is formed predominantly in SNe of type Ia with a delay of ~1 Gyr and assuming as cosmological parameters H_o = 72 km/s Mpc, Omega_M = 0.3, and Omega_Lambda = 0.7$, we conclude that major star formation activity in the host galaxies of our z=3.4 quasars must have started already at an epoch corresponding to z_f ~= 10, when the age of the universe was less than 0.5 Gyrs.Comment: 29 pages, 5 figures, ApJ in pres

Industrial Groupings and Strategic FDI: Theory and Evidence

We show that industrial ownership structures, such as keiretsu groupings in Japan, may significantly impact firms' incentives to engage in FDI. While the previous literature has mainly focused on the cost of capital advantages enjoyed by keiretsu firms, this paper examines two relatively unexplored channels by which ownership structure matters for FDI incentives. The first channel involves the direct incentives generated via standard product and factor market interactions whereby keiretsu firms with cross-ownership consider more directly the congestion effects of further FDI into a market. The second channel involves the indirect incentives generated by sharing of information across keiretsu firms which reduces entry costs for subsequent FDI. Using data on Japanese FDI activity by both keiretsu and non-keiretsu manufacturing firms, we find evidence to support the importance of the second channel (information-sharing incentives) as an explanation for firm-level FDI patterns, but not for the first channel.