50,148 research outputs found

    In Defense of the Ordinary / Extraordinary Distinction

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    The author, an assistant professor of philosophy at Emory and Henry College, Emory, Virginia, explains that his paper defends the traditional doctrine against a recent proposal by Robert M. Veatch inhis popular Death, Dying, and the Biological Revolution

    Trade-off between Linewidth and Slip Rate in a Mode-Locked Laser Model

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    We demonstrate a trade-off between linewidth and loss-of-lock frequency in a mode-locked laser employing active feedback to control the carrier-envelope offset phase difference. In frequency metrology applications, the linewidth translates directly to uncertainty in the measured frequency, while the impact of lock loss and recovery on the measured frequency is less well understood. We reduce the dynamics to stochastic differential equations, specifically diffusion processes, and compare the linearized linewidth to the rate of lock loss determined by the mean time to exit calculated from large deviation theory.Comment: 5 pages, 4 figure

    The Great Naval Battle of North Point: Myth or Reality?

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    Hollywood itself could hardly have scripted a better battle. According to eyewitnesses, a German U-boat lurking off the shores of North Point, Prince Edward Island, laid a trap for an unsuspecting convoy transitting the Northumberland Strait. On 7 May 1943, the trap was sprung, Canadian naval escorts and aircraft did their best to defend the beleaguered convoy from a brazen and unorthodox attack that was unlike any other. There could only be one conclusion: the German commander was half-mad. Just like the fictional Captain Ahab, he was willing to take unwarranted risks with his boat and men to destroy his white whale that came in the form of a troop ship at the centre of the convoy. His obsession led to a stunning three hour engagement that was brought to a dramatic end as the Canadians scored a direct hit forcing the U-boat’s bow to rise sharply out of the water before sinking. The problem is that there is no evidence that this battle ever took place

    Part Of An Answer To Melville\u27s Bartleby

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    In lieu of an abstract, below is the essay\u27s first paragraph. The land was troubled by a wind, a wind of two years\u27 strength, and it had blown with gathering force for at least that long. A small boy Nameless travelled a roadway that seemed to drive the land along with it, that seemed to give reason and expression to the land. The land seemed made only for the roadway

    Cargo transfer vehicle RCS propellant contamination issues

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    The purpose of this report is to address Cargo Transfer Vehicle (CTV) RCS contamination issues and contribute to the resources necessary to optimize the vehicle and propulsion systems required in the CTV of the National Launch System (NLS) Heavy Lift Launch Vehicle (HLLV). This study reviews the thruster-induced contaminants; their transportation from the thrust chamber to the vehicle, payload, and SSF; and the mechanism by which damage is inflicted on their components. The effect of both monopropellant and bipropellant RCS rocket exhaust plumes on a spacecraft and related functional surfaces has been the subject of considerable study over the years. It is recognized that the RCS rocket produces contaminants which can significantly degrade the performance of optical windows, solar cells, thermal-protective coatings, and other external vehicle components. This is particularly true when the rocket is operating in the pulse mode. The exhaust plume impingement pressure and heat-transfer phenomena also complicate the environment to which the vehicle and its functional surfaces are exposed, but are not addressed in this study. Bipropellant contamination presented several modes of damage to incident surfaces, which can pose a long-term deleterious consequence to CTV payloads and the Space Station Freedom (SSF). Monopropellant contamination did not pose any significant long-term issues other than the possibility of aniline deposition. The use of either bipropellant and monopropellant propulsion systems can have a design impact on the CTV propulsion system with respect to maneuvering operations in the proximity of SSF

    An architecture for integrating distributed and cooperating knowledge-based Air Force decision aids

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    MITRE has been developing a Knowledge-Based Battle Management Testbed for evaluating the viability of integrating independently-developed knowledge-based decision aids in the Air Force tactical domain. The primary goal for the testbed architecture is to permit a new system to be added to a testbed with little change to the system's software. Each system that connects to the testbed network declares that it can provide a number of services to other systems. When a system wants to use another system's service, it does not address the server system by name, but instead transmits a request to the testbed network asking for a particular service to be performed. A key component of the testbed architecture is a common database which uses a relational database management system (RDBMS). The RDBMS provides a database update notification service to requesting systems. Normally, each system is expected to monitor data relations of interest to it. Alternatively, a system may broadcast an announcement message to inform other systems that an event of potential interest has occurred. Current research is aimed at dealing with issues resulting from integration efforts, such as dealing with potential mismatches of each system's assumptions about the common database, decentralizing network control, and coordinating multiple agents

    A primer on noise-induced transitions in applied dynamical systems

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    Noise plays a fundamental role in a wide variety of physical and biological dynamical systems. It can arise from an external forcing or due to random dynamics internal to the system. It is well established that even weak noise can result in large behavioral changes such as transitions between or escapes from quasi-stable states. These transitions can correspond to critical events such as failures or extinctions that make them essential phenomena to understand and quantify, despite the fact that their occurrence is rare. This article will provide an overview of the theory underlying the dynamics of rare events for stochastic models along with some example applications

    Evaluation of Forearm Muscle Fatigue from Operating a Motorcycle Clutch

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    A laboratory experiment evaluated the effect of motorcycle clutch design on the electromyography (EMG) activity of the primary agonist finger flexor muscle in the forearm. The goal was to compare muscle fatigue resulting from operation of two different motorcycle clutches in simulated traffic. EMG activity from the flexor digitorum superficialis (FDS) muscle of 12 female and 11 males were recorded while each participant operated an existing motorcycle clutch (requiring 98 N peak force) as well as an alternate design (requiring 36 N peak force) during 60-minute simulations. Muscle fatigue was quantified by measuring the decrease in median frequency of the EMG signals. Compared to operating the existing clutch, male participants experienced a significant decrease in muscle fatigue between 14 to 31% when operating the alternate clutch. Females experienced a decrease of 27 to 49%. In addition to reduced muscle fatigue, the alternate clutch was overwhelmingly preferred by participants and was rated superior for ease of use and comfort. Results provide a better understanding of the effect of clutch design on riders’ muscular loading and implications for design improvements

    Lithium abundances in exoplanet host stars as test of planetary formation scenarii

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    Following the observations of Israelian et al. 2004, we compare different evolutionary models in order to study the lithium destruction processes and the planetary formation scenarii.Comment: 4 pages, 5 figures, proceeding of the meeting "Element Stratification in stars : 40 years of atomic diffusion", Mons 6-11 Juin 200
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