The Use of Multi-beam Sonars to Image Bubbly Ship Wakes

During the past five years, researchers at Penn State University (PSU) have used upward-looking multi-beam (MB) sonar to image the bubbly wakes of surface ships. In 2000, a 19-beam, 5° beam width, 120° sector, 250 kHz MB sonar integrated into an autonomous vehicle was used to obtain a first-of-a-kind look at the three-dimensional variability of bubbles in a large ship wake. In 2001 we acquired a Reson 8101 MB sonar, which operates at 240 kHz and features 101-1.5º beams spanning a 150º sector. In July 2002, the Reson sonar was deployed looking upward from a 1.4 m diameter buoy moored at 29.5 m depth in 550 m of water using three anchor lines. A fiber optic cable connected the sonar to a support ship 500 m away. Images of the wake of a small research vessel provided new information about the persistence of bubble clouds in the ocean. An important goal is to use the MB sonar to estimate wake bubble distributions, as has been done with single beam sonar. Here we show that multipath interference and strong, specular reflections from the sea surface adversely affect the use of MB sonars to unambiguously estimate wake bubble distributio

Composers' Forum Student Works, February 3, 1987

This is the concert program of the Composers' Forum Student Works performance on Tuesday, February 3, 1987 at 12:30 p.m., at the Concert Hall, 855 Commonwealth Avenue. Works performed were Lagu Laut by Arthur Levering, Scordatura for 40 open strings and 154 harmonies by Daniel Kastner, Wu-Ti by Shih-Hui Chen, and Five Preludes for solo piano by Michalis Lapidakis. Digitization for Boston University Concert Programs was supported by the Boston University Humanities Library Endowed Fund

13.0.G Message end of class Day 13

WELCOME to WINDOWS on the INQUIRY CLASSROOM! You have landed on a piece of a National Science Foundation Project (DUE 1245730) directed by Professor Chris Bauer, Chemistry Department, University of New Hampshire. This is one part of a completely documented inquiry-based university science course called “Fire & Ice” which explores the nature of heat and temperature. There are multiple video perspectives and commentary from instructors and students, and documents of all course materials (agenda, instructions, student work). It’s too complicated to explain here. Take a look at the user orientation document at this link

Operational Currency Mismatch and Firm Level Performance: Evidence from India

This paper looks at the determinants and effects of exchange rate exposure using data on 500 Indian firms over the period 1995-2011. Unlike the existing papers in the literature, we use a measure of `operational` currency exposure based on foreign currency revenues and costs of firms. Among other factors, exchange rate volatility appears as a significant determinant of average firm level exposure with the direction of relationship supporting the presence of `Moral Hazard` in firm’s risk taking behavior. Further large `operational` exposure is associated with significantly lower output growth, profitability and capital expenditure during episodes of large currency depreciation at the firm level. Together this indicates that the policy makers must take into account the incentive effects of their intervention in foreign exchange markets.