2,931 research outputs found

    A computer aided teleoperator system Final report

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    Computer aided teleoperator system for remote handling task

    High performance extendable instruction set computing

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    In this paper, a new architecture called the extendable instruction set computer (EISC) is introduced that addresses the issues of memory size and performance in embedded microprocessor systems. The architecture exhibits an efficient fixed length 16-bit instruction set with short length offset and immediate operands. The offset and immediate operands can be extended to 32 bits via the operation of an extension flag. The code density of the EISC instruction set and its memory transfer erformance is shown to be significantly higher than current architectures making it a suitable candidate for the next generation of embedded computer systems. The compact EISC instruction set introduces data dependencies that seemingly limit deep pipeline and superscalar implementations. This paper suggests a mechanism by which these dependencies might be removed in hardware

    Seasonal Use of Bridges by Rafinesque\u27s Big-Eared Bat, \u3ci\u3eCorynorhinus rafinesquii\u3c/i\u3e, in Southern Mississippi

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    We conducted surveys of concrete bridges in southern Mississippi from 2000–2002 to determine the phenological pattern of use by Rafinesque\u27s big-eared bat, Corynorhinus rafinesquii. The earliest dates on which we located maternity colonies were 9 March 2000, 20 April 2001, and 15 May 2002. Maternity colonies increased in size and abundance as spring progressed. Pups were born in mid- to late May (first observed 12 May 2000, 15 May 2001, 27 May 2002) and nursed through midsummer (lactating females last captured 14 July 2000, 25 July 2001, 16 July 2002). Colony size and percentage of bridges occupied by bats declined in late summer. Colonies were absent during fall and winter, although we occasionally found solitary individuals during these seasons. Number of bats present under an occupied bridge ranged from 1 to 25. The mean number of individuals per occupied bridge was 4.6 (SD = 5.8) in 2000, 3.9 (SD = 5.0) in 2001, and 3.0 (SD = 4.4) in 2002. The mean number of adult females per maternity colony was 5.6 (SD = 3.1). Although we found males throughout the study period, females were largely absent from bridges outside of the maternity season, suggesting that much of the population used alternate roosts during this time

    Event-Driven Network Programming

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    Software-defined networking (SDN) programs must simultaneously describe static forwarding behavior and dynamic updates in response to events. Event-driven updates are critical to get right, but difficult to implement correctly due to the high degree of concurrency in networks. Existing SDN platforms offer weak guarantees that can break application invariants, leading to problems such as dropped packets, degraded performance, security violations, etc. This paper introduces EVENT-DRIVEN CONSISTENT UPDATES that are guaranteed to preserve well-defined behaviors when transitioning between configurations in response to events. We propose NETWORK EVENT STRUCTURES (NESs) to model constraints on updates, such as which events can be enabled simultaneously and causal dependencies between events. We define an extension of the NetKAT language with mutable state, give semantics to stateful programs using NESs, and discuss provably-correct strategies for implementing NESs in SDNs. Finally, we evaluate our approach empirically, demonstrating that it gives well-defined consistency guarantees while avoiding expensive synchronization and packet buffering

    Survey of Salamanders in Mississippi Limestone Caves

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    During 2000-2002 we surveyed for salamanders in the larger limestone caves of Mississippi, all within the Vicksburg Group rock unit. We found four species: Plethodon mississippi was the most abundant, followed by Eurycea guttolineata, Eurycea cirrigera, and Desmognathus conanti. We did not find Pseudotriton montanus in any of the caves, and question the validity of an investigator\u27s statement made nearly 45 years ago that, it is one of the most numerous salamanders in Mississippi. limestone caves. The salamander fauna we found is similar to that of the only other comprehensive survey of salamanders in Mississippi caves, conducted almost thirty years ago
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