6,582 research outputs found
The impact of monetary policy on New Zealand business cycles and inflation variability
This paper uses the open economy structural VAR model developed in Buckle, Kim, Kirkham, McLellan and Sharma (2002) to evaluate the impact of monetary policy on New Zealand business cycles and inflation variability and the output/ inflation variance trade-off. The model includes a forward- looking Taylor Rule to identify monetary policy and the impact of monetary policy is evaluated by deriving a monetary policy index using a procedure suggested by Dungey and Pagan (2000). Monetary policy has generally been counter-cyclical, thereby reducing business cycles and inflation variability. Exceptions are in 1993 when monetary policy accentuated the business cycle upswing and in 1998 when monetary policy accentuated the recession, although its impact in 1998 was small relative to the impact of adverse climatic conditions. During the initial years of inflation targeting monetary policy tended to simultaneously reduce inflation and output variability. From 1996 to 2001 monetary policy was less effective in reducing inflation and output variability. This latter period included a brief experiment with a Monetary Conditions Index, the Asian crisis and a large adverse domestic climate shock.Monetary policy; inflation targeting, business cycles; open economy; structural VAR models; inflation, interest rates, exchange rates, climate; international linkages
Effects of bubbles on the electrochemical behavior of hydrogen-evolving Si microwire arrays oriented against gravity
The size-distribution, coverage, electrochemical impedance, and mass-transport properties of H₂ gas-bubble films were measured for both planar and microwire-array platinized n⁺-Si cathodes performing the hydrogen-evolution reaction in 0.50 M H₂SO₄ (aq). Inverted, planar n⁺-Si/Ti/Pt cathodes produced large, stationary bubbles which contributed to substantial increases in ohmic potential drops. In contrast, regardless of orientation, microwire array n⁺-Si/Ti/Pt cathodes exhibited a smaller layer of bubbles on the surface, and the formation of bubbles did not substantially increase the steady-state overpotential for H₂ (g) production. Experiments using an electroactive tracer species indicated that even when oriented against gravity, bubbles enhanced mass transport at the electrode surface. Microconvection due to growing and coalescing bubbles dominated effects due to macroconvection of gliding bubbles on Si microwire array cathodes. Electrodes that maintained a large number of small bubbles on the surface simultaneously exhibited low concentrations of dissolved hydrogen and small ohmic potential drops, thus exhibiting the lowest steady-state overpotentials. The results indicate that microstructured electrodes can operate acceptably for unassisted solar-driven water splitting in the absence of external convection and can function regardless of the orientation of the electrode with respect to the gravitational force vector
Ultraspinning limits and super-entropic black holes
By employing the new ultraspinning limit we construct novel classes of black
holes with non-compact event horizons and finite horizon area and study their
thermodynamics. Our ultraspinning limit can be understood as a simple
generating technique that consists of three steps: i) transforming the known
rotating AdS black hole solution to a special coordinate system that rotates
(in a given 2-plane) at infinity ii) boosting this rotation to the speed of
light iii) compactifying the corresponding azimuthal direction. In so doing we
qualitatively change the structure of the spacetime since it is no longer
possible to return to a frame that does not rotate at infinity. The obtained
black holes have non-compact horizons with topology of a sphere with two
punctures. The entropy of some of these exceeds the maximal bound implied by
the reverse isoperimetric inequality, such black holes are super-entropic.Comment: 19 pages, 6 figures; minor corrections as in published version,
updated reference
Ultraspinning limits and rotating hyperboloid membranes
We apply the hyperboloid membrane limit to the general Kerr-AdS metrics and
their recently studied super-entropic cousins and obtain a new class of
rotating black holes, for which the rotational parameters in multiple
directions attain their maximal value---equal to the AdS radius. These new
solutions have a potential application in the description of holographic fluids
with vorticity. They also possess interesting thermodynamic properties: we show
that---despite the absence of Misner strings---the Bekenstein--Hawking
entropy/area law is still violated, raising a question about the origin of this
violation.Comment: 10 pages, 2 figures, REVTeX 4-
A structural VAR model of the New Zealand business cycle
This paper develops a new open economy structural VAR model of the New Zealand economy. The model adopts techniques introduced by Cushman and Zha (1997) and Dungey and Pagan (2000) to identify international and domestic shocks and dynamic responses to these shocks in a small open economy. The international variables are block exogenous and the model includes restrictions on contemporaneous and lagged variables. Novel features include the introduction of an expanded set of domestic financial variables not captured in previous New Zealand VAR models, the use of a forward looking Taylor Rule to identify monetary policy, and the introduction of a climate variable to capture the impact of climatic conditions on the business cycle. Key results to emerge are the significant influence of international variables on the New Zealand business cycle, the importance of separately identifying import price and export price shocks, and the significant influence of climate.Open economy; structural VAR models; business cycles; climate; commodity prices; international linkages; financial conditions.
Thermal Mechanical Stability of Single-Crystal-Oxide Refractive Concentrators Evaluated for High-Temperature Solar-Thermal Propulsion
Recently, refractive secondary solar concentrator systems were developed for solar thermal power and propulsion (ref. 1). Single-crystal oxides-such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO), and sapphire (Al2O3)-are candidate refractive secondary concentrator materials. However, the refractive concentrator system will experience high-temperature thermal cycling in the solar thermal engine during the sun/shade transition of a space mission. The thermal mechanical reliability of these components in severe thermal environments is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions. In this research at the NASA Lewis Research Center, a controlled heat flux test approach was developed for investigating the thermal mechanical stability of the candidate oxide. This approach used a 3.0-kW continuous-wave (wavelength, 10.6 mm) carbon dioxide (CO2) laser (ref. 2). The CO2 laser is especially well-suited for single-crystal thermal shock tests because it can directly deliver well-characterized heat energy to the oxide surfaces. Since the oxides are opaque at the 10.6-mm wavelength of the laser beam, the light energy is absorbed at the surfaces rather than transmitting into the crystals, and thus generates the required temperature gradients within the specimens. The following figure is a schematic diagram of the test rig
Organizational Design for Spill Containment in Deepwater Drilling Operations in the Gulf of Mexico: Assessment of the Marine Well Containment Company (MWCC)
The Deepwater Horizon oil spill in the Gulf of Mexico in April 2010 led to the deaths of 11 workers, a six-month moratorium on deepwater drilling in the Gulf, and nearly three months of massive engineering and logistics efforts to stop the spill. The series of failures before the well was finally capped and the spill contained revealed an inability to deal effectively with a well in deepwater and ultradeepwater. Ensuring that containment capabilities are adequate for drilling operations at these depths is therefore a salient challenge for government and industry. In this paper we assess the Marine Well Containment Company (MWCC), a consortium aimed at designing and building a system capable of containing future deepwater spills in the Gulf. We also consider alternatives for long-term readiness for deepwater spill containment. We focus on the roles of liability and regulation as determinants of readiness and the adequacy of incentives for technological innovation in oil spill containment technology to keep pace with advances in deepwater drilling capability. Liability and regulation can significantly influence the strength of these incentives. In addition, we discuss appropriate governance structure as a major determinant of the effectiveness of MWCC.oil spill, containment, industry R&D, liability, regulation, governance, innovation
Model for Alumina nanopore-based Optical Filter
Alumina nanopore structures find applications in magnetic sensors, optical filters, and various biological devices. In this work, we present a ray-optics model for the optical filter. We present a detailed simulation and a simplified analytical expression for the reflectance as a function of the alumina parameters such as pore diameter, pore density, alumina thickness, and a function of the wavelength and angle of incidence of the illuminating plane electromagnetic wave. The reflectance vs wavelength in the range of 400–800nm obtained from the simulation and the analytical expression are compared with that of the experiments for thin and thick alumina. All results agree well for a thin layer of alumina pores (90nm) . When comparing experimental and theoretical results for a thick layer of alumina (1300nm) , the results disagree. One possible explanation for the discrepancy is that the dielectric constant may vary with the thickness of the anodized alumina. Based on this work, a ray optic mixing theory is presented for waves propagating obliquely to parallel slabs of dielectric mediums with a degree of spatial periodicity
On the stability of the Discrete Generalized Multigroup method
This paper investigates the stability of the recondensation procedure of the Discrete Generalized Multigroup method and proposes alternatives to improve stability of the original formulation. Instabilities are shown to happen when employing a simple Picard fixed point iteration and an ill-informed group mapping scheme. This work presents a mapping procedure that improves stability of the original method for fine group calculations. Additionally, a relaxation scheme, Krasnoselskij iteration, is introduced to the fixed point iteration to further improve the stability characteristics and remove the need for fine group flux updates. Both improvements are applied on heterogeneous problems using the SHEM361 and the NG2042 group structures. The results indicate improved stability from a well-informed group mapping and demonstrate the possibility of eliminating the need for fine group flux updates.United States. Dept. of Energy. Naval Reactors Divisio
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