Process Control of 3D Welding as a Droplet-Based Rapid Prototyping Technique

Three-dimensional welding is investigated as a rapid prototyping technique for the production of real Inetallic parts using gas metal arc welding principles. A high speed machine vision system is used to study the correlation between droplet transfer parameters and resultant weld penetration characteristics. Experimental work is conducted to determine how droplet transfer frequency, droplet size, and number of passes affect the geometrical and Inetallurgical properties ofthe weld penetration. A finite element analysis is performed in order to study what influence additional layering has on the cooling characteristics and resultant penetration profile.Mechanical Engineerin

Measuring the Impact of Regulationon Market Stability: Evidence from the US Markets

In this paper, we introduce a new methodology designed to test the effect of new regulatory disclosure requirements on the disclosure threshold as predicted by the extant literature (Verrecchia (1983), Dye (1985)). We apply our methodology to test the consistency between observed effects from major US regulation past and present (1933/1934 Securities Acts, Regulation Fair Disclosure 2000, and the Sarbanes-Oxley Act 2002) with regulatory objectives.

The Effectiveness of Britain's Financial Service Authority: An Economic Analysis

Sweeping regulatory reforms in Britain resulted in the formation of the Financial Services Authority (FSA). Because greater transparency of information is a major objective for this Act, shifting from one information system to another has re-distributive effects. We identify these effects at a sector level and their drivers at the firm level. At a sector level, FSA has generally increased the precision of investors’ priors reducing the information risk component of the cost of capital. At a firm level, large firms act as “Stackelberg leaders” in voluntary disclosure games. FSA regulation shifts power from leaders to “followers”.Disclosure, Regulation, Game Theory, Stackelberg Leader, Cost of Capital: information asymmetry

The Financial Services Reform Act 2001: Impact on Systemic risk in Australia

The rise of conglomerate banks and their interrelated balance sheets, pose new challenges to theories of financial regulation. We measure the impact of recent legislative changes in Australia upon systemic risk, for banking and near banking sectors, and demonstrate a significant reduction post the legislation. This is consistent with a major legislative goal, to promote global competitiveness, because it implies a reduction in the cost of equity capital. In addition, we find no evidence in support of the HIH collapse increasing systemic risk in the overall financial sector but a relatively small effect was detected in the banking sector.Ris, Banks, Disclosure, Regulation, Entropy

On the Margins of Sustainability. Prehistoric Settlement of Utrok Atoll, Northern Marshall Islands (Review)

On the Margins of Sustainability. Prehistoric Settlement of Utrok Atoll, Northern Marshall Islands Marshall I. Weisler BAR International Series 967, Archaeopress, Oxford. 2001. 144 pp. (122 B&W figures, photographs, maps and drawings, 24 tables, 3 appendices) £28.00 (US$40.00), paper. ISBN 1-84171-254-X Review by Felicia R. Beardsley, Ph.D.</p

A Correlation Between Changes in Solar Luminosity and Differential Radius Measurements

Solar luminosity variations occurring during solar cycle 21 can be attributed in large part to the presence of sunspots and faculae. Nevertheless, there remains a residual portion of the luminosity variation distinctly unaccounted for by these phenomena of solar activity. At the Santa Catalina Laboratory for Experimental Relativity by Astrometry (SCLERA), observations of the solar limb are capable of detecting changes in the solar limb darkening function by monitoring a quantity known as the differential radius. These observations are utilized in such a way that the effects of solar activity are minimized in order to reveal the more fundamental structure of the photosphere. The results of observations made during solar cycle 21 at various solar latitudes indicate that a measurable change did occur in the global photospheric limb darkening function. It is proposed that the residual luminosity change is associated in part with this change in limb darkening

Simulation of aromatic SOA formation using the lumping model integrated with explicit gas-phase kinetic mechanisms and aerosol-phase reactions

The Unified Partitioning-Aerosol phase Reaction (UNIPAR) model has been developed to predict the secondary organic aerosol (SOA) formation through multiphase reactions. The model was evaluated with aromatic SOA data produced from the photooxidation of toluene and 1,3,5-trimethylbenzene (135-TMB) under various concentrations of NO_x and SO₂ using an outdoor reactor (University of Florida Atmospheric PHotochemical Outdoor Reactor (UF-APHOR) chamber). When inorganic species (sulfate, ammonium and water) are present in aerosol, the prediction of both toluene SOA and 135-TMB SOA, in which the oxygen-to-carbon (O : C) ratio is lower than 0.62, are approached under the assumption of a complete organic/electrolyte-phase separation below a certain relative humidity. An explicit gas-kinetic model was employed to express gas-phase oxidation of aromatic hydrocarbons. Gas-phase products are grouped based on their volatility (6 levels) and reactivity (5 levels) and exploited to construct the stoichiometric coefficient (&alpha;_i,j) matrix, the set of parameters used to describe the concentrations of organic compounds in multiphase. Weighting of the &alpha;_i,j matrix as a function of NO_x improved the evaluation of NO_x effects on aromatic SOA. The total amount of organic matter (OM_T) is predicted by two modules in the UNIPAR model: OM_P by a partitioning process and OM_AR by aerosol-phase reactions. The OM_AR module predicts multiphase reactions of organic compounds, such as oligomerization, acid-catalyzed reactions, and organosulfate (OS) formation. The model reasonably simulates SOA formation under various aerosol acidities, NO_x concentrations, humidities and temperatures. Furthermore, the OS fractions in the SOA predicted by the model were in good agreement with the experimentally measured OS fractions

The FHD/ε\boldsymbol{\varepsilon}ppsilon Epoch of Reionization Power Spectrum Pipeline

Epoch of Reionization data analysis requires unprecedented levels of accuracy in radio interferometer pipelines. We have developed an imaging power spectrum analysis to meet these requirements and generate robust 21 cm EoR measurements. In this work, we build a signal path framework to mathematically describe each step in the analysis, from data reduction in the FHD package to power spectrum generation in the $\varepsilon$ppsilon package. In particular, we focus on the distinguishing characteristics of FHD/$\varepsilon$ppsilon: highly accurate spectral calibration, extensive data verification products, and end-to-end error propagation. We present our key data analysis products in detail to facilitate understanding of the prominent systematics in image-based power spectrum analyses. As a verification to our analysis, we also highlight a full-pipeline analysis simulation to demonstrate signal preservation and lack of signal loss. This careful treatment ensures that the FHD/$\varepsilon$ppsilon power spectrum pipeline can reduce radio interferometric data to produce credible 21 cm EoR measurements.Comment: 21 pages, 10 figures, accepted by PAS

Observations of tidal variability on the New England shelf

Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): C06010, doi:10.1029/2003JC001972.Observations from the Coastal Mixing and Optics experiment moored array, deployed from August 1996 through June 1997, are used to describe barotropic and baroclinic tidal variability over the New England shelf. The dominant M 2 tidal elevations decrease toward the northeast to a minimum over the Nantucket shoals (about 34 cm), and barotropic tidal current amplitudes increase strongly toward the northeast to a maximum over the shoals (about 35 cm s−1). Estimates of the depth-averaged M 2 momentum balance indicate that tidal dynamics are linear, and along-shelf pressure gradients are as large as cross-shelf pressure gradients. In addition, tidal current ellipses are weakly polarized, confirming that the dynamics are more complex than simple plane waves. The vertical structure of the M 2 currents decreases in amplitude and phase (phase lead near bottom) over the bottom 20 m. The M 2 momentum deficit near the bottom approximately matches direct covariance estimates of stress, confirming the effects of stress on current structure in the tidally driven bottom boundary layer. Baroclinic current variability at tidal frequencies is small (2 cm s−1 amplitude), with a predominantly mode 1 vertical structure. High-frequency (approaching the buoyancy frequency) internal solitons are observed following the pycnocline. The internal solitons switch from waves of depression to waves of elevation when the depth of maximum stratification is deeper than half the water column depth. Both low-mode baroclinic tidal and high-frequency internal wave energy decrease linearly with bottom depth across the shelf.Funding for the CMO experiment and subsequent analysis was provided by the Office of Naval Research under grants N00014-95-1-0339 and N00014-01-1-0140