A conventional point of view on active magnetic bearings

Active magnetic bearings used in rotating machinery should be designed as locally controlled, independent devices similar to other types of bearings. The functions of control electronics and power amplifiers can be simply and explicitly related to general bearing properties such as load capacity, stiffness, and damping. The dynamics of a rotor and its supporting active magnetic bearings are analyzed in a modified conventional method with an extended state vector containing the bearing state variables

Counterfactual Estimation and Optimization of Click Metrics for Search Engines

Optimizing an interactive system against a predefined online metric is particularly challenging, when the metric is computed from user feedback such as clicks and payments. The key challenge is the counterfactual nature: in the case of Web search, any change to a component of the search engine may result in a different search result page for the same query, but we normally cannot infer reliably from search log how users would react to the new result page. Consequently, it appears impossible to accurately estimate online metrics that depend on user feedback, unless the new engine is run to serve users and compared with a baseline in an A/B test. This approach, while valid and successful, is unfortunately expensive and time-consuming. In this paper, we propose to address this problem using causal inference techniques, under the contextual-bandit framework. This approach effectively allows one to run (potentially infinitely) many A/B tests offline from search log, making it possible to estimate and optimize online metrics quickly and inexpensively. Focusing on an important component in a commercial search engine, we show how these ideas can be instantiated and applied, and obtain very promising results that suggest the wide applicability of these techniques

Mystery and the Mastery of the Judicial Power, The

What do law clerks do at the Supreme Court? One day this question took me entirely by surprise. Not because of its substance: I have repeatedly answered this question ever since Justice Clarence Thomas invited me to serve as his clerk for October Term 1992. As with so much else in law, context had triumphed over content

The Constitutional Law Songbook

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Law As a Species of Language Acquisition

Without fanfare, Plain Meaning and Hard Cases relegated its discussion of phonetics, phonology, and morphology to a single footnote. One must strain to imagine how the mechanics of sound production or the sound system of the English language might affect the law. Linguistics at too high a level of abstraction likewise seems unhelpful. American law rarely considers the nuances of foreign languages,\u27 and a fortiori the entire field of comparative linguistics, especially as applied in the ongoing search for linguistic universals, seemingly lies outside the useful domain of law and linguistics. This assumption is demonstrably wrong. To the extent that we legal writers might believe otherwise, we have only ourselves to blame. We have been misunderstanding the relation between law and linguistics all along

Across the Apocalypse on Horseback: Imperfect Legal Responses to Biodiversity Loss

Life on Earth overcomes mass extinction events on a temporal scale spanning millions of years. By this measure, “the loss of genetic and species diversity” is probably the contemporary crisis “our descendants [will] most regret” and “are least likely to forgive.” Biodiversity loss is the “scientific problem of greate[st] immediate importance for humanity.” If indeed biodiversity loss has reached apocalyptic proportions, it is fitting to describe the engines of extinction in equine terms. Jared Diamond characterizes the deadly horsemen of the ecological apocalypse as an “Evil Quartet” consisting of habitat destruction, overkill, introduced species, and secondary extinctions. Edward O. Wilson prefers an acronym derived from the Greek word for horse. HIPPO represents Habitat destruction, Invasive species, Pollution, Population, and Overharvesting. Although conservation biologists have identified the leading causes of biodiversity loss, legal responses to the crisis do not address distinct sources of human influence on evolutionary change. Not surprisingly, legal scholarship tends to ignore the distinctions among causes of biodiversity loss. This Essay takes a modest step toward remedying at least the latter shortcoming

W.J.B., Vox Populi

William Jennings Bryan dominated the Democratic Party-and arguably American politics at large-for nearly three decades. Thrice he sought the presidency. Thrice he lost. Perhaps no other American politician has had greater influence by losing. Precisely two moments from the life of William Jennings Bryan define this politician\u27s place in the public\u27s eye: Bryan\u27s Cross of Gold speech from the 1896 Democratic Convention in Chicago and his humiliation at the hands of Clarence Darrow in the trial of John Scopes at Dayton, Tennessee. W.J.B. lost nearly every political campaign he undertook. In defeat, he led coalitions of farmers, laborers, believers, and agitators. Indeed, he inspired them. He never served as President, and given his woeful performance as Secretary of State, America is likely blessed to have known him strictly as a presidential candidate. W.J.B. was the prophet of free silver and the scourge of evolution, but he was much, much more. Today, as during the days of his life, W.J.B. is the voice of the people