Acceleration feedback control of human-induced floor vibrations

Active vibration control (AVC) via a proof-mass actuator is considered to be a suitable technique for the mitigation of vibrations caused by human motions in floor structures. It has been observed that actuator dynamics strongly influence structure dynamics despite considering collocated actuator/sensor control. The well-known property of the interlacing of poles and zeros of a collocated control system is no longer accomplished. Therefore, velocity-based feedback control, which has been previously used by other researchers, might not be a good solution. This work presents a design process for a control scheme based on acceleration feedback control with a phase-lag compensator, which will generally be different from an integrator circuit. This first-order compensator is applied to the output (acceleration) in such a way that the relative stability and potential damping to be introduced are significantly increased accounting for the interaction between floor and actuator dynamics. Additionally, a high-pass filter designed to avoid stroke saturation is applied to the control signal. The AVC system designed according to this procedure has been assessed in simulation and successfully implemented in an in-service open-plan office floor. The actual vibration reductions achieved have been approximately 60% for walking tests and over 90% for a whole-day vibration monitoring. (C) 2009 Elsevier Ltd. All rights reserved

The Logic of Solidarity: Social Structure in Le Chambon-Feugerdilles

http://deepblue.lib.umich.edu/bitstream/2027.42/50919/1/144.pd

If You Lose, It Is Binding, but If You Win - They Get a New Trial: Illinois Uninsured Motorist Arbitration

In Reed v. Farmers Insurance Group the Illinois Supreme Court-by a 4-3 vote-upheld an arbitration system in which injury victims are bound by awards below $20,000, but in which insurance companies can insist on a trial de novo for awards over that amount.\u27 A recent legislative enactment has complicated the threshold at which awards change from binding to non-binding, by increasing it to$50,000. However, even in cases where a higher threshold applies, those injury victims receiving awards below the threshold (or losing on the issue of liability) are bound by the arbitration, while injury victims receiving awards higher than the threshold can be required to re-litigate their cases de novo in the court system. This is the arbitration system that awaits Illinois drivers, passengers, and pedestrians who are injured today by uninsured motorists

Labor History Symposium: Gerald Friedman, Reigniting the Labor Movement

When trade union growth worldwide came to a halt in the 1980s, a wide body of literature appeared on the causes of trade union decline. Since that time an even more substantial number of books and articles have been penned on the possibility of trade union revitalization: which combination of factors might lead to resurgence; what organizational forms are best suited to the new political and economic landscape; which goals, strategies and tactics are most likely to spark a reversal of trade unionism’s fortunes. Gerald Friedman, Professor of Economics at the University of Massachusetts and the US editor of this journal, has contributed impressively to these ongoing debates in his Reigniting the Labor Movement. One of the strengths of this important book is its historical and transnational approach. Friedman skilfully weaves together a century’s worth of data from 16 countries to support his principal argument that strikes hold the key to any understanding of the rise, decline and possible resurgence of the labour movement. Trade unions, he argues, must enhance internal democracy in order to facilitate militancy. An indispensible book for all concerned with the present and future prospects of trade unionism, Reigniting the Labor Movement is here examined by four of the leading authorities on that subject

Strike waves, union growth and the rank-and-file/bureaucracy interplay : Britain 1889-1890, 1910-1913 and 1919-1920

Gerald Friedman's Reigniting the Labor Movement was a highly ambitious, unashamedly partisan, historical and transnational comparative analysis of the rise and demise of the labour movement, which identified the way in which rank-and-file workers' spontaneous and innovative strike militancy represents an ‘incipient rebellion against the capitalist system’. In the process, the book made a compelling case for the restoration of past militant worker action as an essential means of ‘reigniting’ the contemporary labour movement. While I find myself in considerable sympathy and agreement with much of the overall analysis, there are distinct but related features of Friedman's thesis that are critically explored in this article. These concern the nature of the relationship between strike movements and union membership growth, and the process by which the unions that emerge from periods of radical labour unrest then seek to dampen down worker militancy in order to bargain with employers/state within the confines of capitalism. My reassessment of Friedman's analysis, framed specifically within the national context of the UK during the historical window of the late nineteenth and early twentieth centuries (specifically 1889–1920), aims to illustrate what I regard as five of the main problematic features of the study

The Ties Allowed to Bind: Kinship Legalities and Migration Restriction in the Interwar Americas

AbstractNew immigration restrictions in the United States and elsewhere in the 1920s and 1930s made legal entry dependent on specific kinship formalities. This article explores the impact of the new system through a study of British Caribbean migrants. Because family patterns and the place of church and state sanction within them varied greatly by class—here, as in many parts of the world—the result was a curtailment of mobility that affected elites very little, and working-class would-be migrants enormously. In order to elucidate de facto patterns of exclusion, the author concludes, historians of transnational labor must begin paying more attention to the work “family” does.</jats:p

Screening migrants in the early Cold War: the geopolitics of U.S. immigration policy

The main elements of U.S. immigration policy date back to the early Cold War. One such element is a screening process initially designed to prevent infiltration by Communist agents posing as migrants from East-Central Europe. The development of these measures was driven by geopolitical concerns, resulting in vetting criteria that favored the admission of hardline nationalists and anti-Communists. The argument proceeds in two steps. First, the article demonstrates that geopolitics influenced immigration policy, resulting in the admission of extremist individuals. Second, it documents how geopolitical concerns and the openness of U.S. institutions provided exiles with the opportunity to mobilize politically. Although there is little evidence that the vetting system succeeded in preventing the entry of Communist subversives into the United States, it did help to create a highly mobilized anti-Communist ethnic lobby that supported extremist policies vis-à-vis the Soviet Union during the early Cold War

Trajectories of Solidarities in France Across Fields of Vulnerability

This chapter approaches the study of solidarity in France by comparing three important vulnerable groups, namely, the disabled, the unemployed, and refugees. The way we approach solidarity hinges on an important distinction between two different meanings of solidarity: solidarity understood as an input and solidarity understood as an output. In particular, we distinguish between two main \u201ctrajectories of solidarity\u201d, which helps us to understand the way certain individual variables (such as self-identification and proximity) combine with political variables (like voting, an interest in politics, or the reading of newspapers) in very different ways. Our main finding is the political trajectory of solidarity can have a remarkable potential even when it comes to helping vulnerable people outside the national boundaries of the political community in France