On the shock transition, the hydraulic jump, and vortex breakdown

The normal shock, hydraulic jump, and vortex breakdown have a common feature: they are all marked by a transition from a supercritical to a subcritical flow state. These phenomena are due to the nonlinearity of the flow, and it will be shown that viscosity also plays an essential role. This paper demonstrates explicitly how viscosity enters into these flows, The treatment of normal shock served a starting illustration. Then an equation governing the phenomenon of hydraulic jump is derived with the inclusion of the effect of viscosity. It is explicitly shown that supercritical flow is not stable and has to go through a transition to a conjugate subcritical flow state downstream. Similar treatment is also applied to vortex breakdown with largely similar results

The wall effect in cavity flow

A non-linear theory for the calculation of the flow field of an oblique flat plate under blockage condition is given using the techniques of integral equations. Numerical results are obtained with the aid of a high speed digital computer for the plate situated mid-channel at values of the angle of attack from 50 to 90° and the channel width-chord ratio from 3 to 20. Also obtained are results for the plate situated at two different off-center positions for a channel width-chord ratio 5 and angles of attack less than 30°

Regionalism picks up speed: New England states find common ground

Initiatives crossing northern New England state borders—including Amtrak’s Downeaster service, joint Maine and New Hampshire efforts to save Portsmouth Naval Shipyard jobs, and Northern Forest Center collaborations—suggest regional economic activity is bigger than ever.Economic conditions - New England ; Industries - New England ; Employment - New England

Remember the Fillmore: The Lingering History of Urban Renewal in Black San Francisco

In the summer of 2008, I moved to San Francisco, California. I lived in the city for three months. As a researcher, my objective was to learn more about Mayor Gavin Newsome’s African-American Out-Migration Task Force. The Task Force convened in 2007 and met eight times from August to December. In 2009, the Mayor\u27s office released a final report on the Redevelopment Agency\u27s website that summarized the history of blacks in the city and outlined several recommendations for reversing their flight. The final report found that the political, economic, and social conditions of African-Americans are disproportionately more dire than any other group in San Francisco. During our conversations, some task force members suggested that this dire condition could be due to the lack of a black middle-class, which could act as a “connective tissue” between San Francisco’s poor black community and the city’s decision makers. The Task Force reported that although blacks had been in San Francisco for decades, many African-Americans, especially poor blacks, often felt disconnected from much of the city life. That finding resonated with what I heard during my interviews with the middle- to upper-middle class African-American members of the Task Force and with my observations of how residents and visitors shared public space in the Fillmore neighborhood, one of the city’s historically black neighborhoods. [excerpt

The Shipbuilding Industry in East and West: Industry Dynamics, Science and Technology Policies and Emerging Patterns of Cooperation

Shipbuilding has changed from a "heavy industry" to become a capital- and technologyintensive activity over the last decades. While Japanese, South Korean and Western European yards dominate the merchant shipbuilding market so far, Eastern European yards are increasingly active, in particular in low and medium complex ships. We develop a market analysis and identify the axes of competition in international civil shipbuilding. From there, we analyze the restructuring process of Eastern European yards. Polish yards have proceeded with relatively quick enterprisation, establishing strong links to domestic and international suppliers. Restructuring in Russian and Ukrainian yards is blocked by local obstacles to enterprization, leading to increasing competitiveness gaps with CEE-yards. We conclude that a science&technology policy should be demand-oriented and target only the clearly identified obstacles to enterprization.

“This Is War”: The Construction of the Laird Rams

By the spring of 1863, American ambassador to England Charles Francis Adams had a much bigger problem than the activities of British-built Confederate raiders on his hands: the construction of two 230-foot long ironclad rams in the Laird shipyard at Birkenhead that evidence suggested were destined for the Confederacy. At 230 feet long and 40 feet wide, with 6-7 foot iron spears at the front, rotating turret batteries, full iron plating, and a top speed of 10 knots, these ships were the Americans’ worst nightmare. Lincoln’s cabinet even considered blatantly ignoring Britain’s “neutrality” and sending a U.S. Navy squadron to destroy the rams, which had been under construction since the previous summer

AZIPOD Propeller Blade Cavitation Observations During Ship Maneuvering

This paper presents results of observations of full-scale propeller blade cavitation patterns carried out on the Elation passenger cruiser, the very first ship equipped with AZIPOD electric thrusters. It offers descriptions of test conditions, cavitation photos for a number of maneuvering modes, including acceleration, steering, initial crash stop phase, some comments on cavitation patterns and conclusions about propeller blade cavitation on the pulling option of azimuthal thrusters

Richard D. Dunphy and The Prices and Prizes of War

Like many immigrants during the mid-nineteenth century, Irishman Richard D. Dunphy served his new country in the Civil War, albeit not entirely willingly. The wounds he sustained during the war were grave, including the loss of both arms. He received some reward for his sacrifice from his country: a monthly pension, a Medal of Honor, and a notability lacked by other faceless coal heavers. As with other great conflicts, the war played a pivotal role in the lives of its participants, especially in the case of Richard Dunphy. [excerpt