2,672 research outputs found

    Two Compact Incremental Prime Sieves

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    A prime sieve is an algorithm that finds the primes up to a bound nn. We say that a prime sieve is incremental, if it can quickly determine if n+1n+1 is prime after having found all primes up to nn. We say a sieve is compact if it uses roughly n\sqrt{n} space or less. In this paper we present two new results: (1) We describe the rolling sieve, a practical, incremental prime sieve that takes O(nloglogn)O(n\log\log n) time and O(nlogn)O(\sqrt{n}\log n) bits of space, and (2) We show how to modify the sieve of Atkin and Bernstein (2004) to obtain a sieve that is simultaneously sublinear, compact, and incremental. The second result solves an open problem given by Paul Pritchard in 1994

    Guide to the meso-scale production of the copepod Acartia tonsa

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    This manual is intended as a guide for the daily production of a few million A. tonsa nauplii for feeding to marine vertebrates and invertebrates. This scale of production is greater than most research would require, but smaller than commercial production, hence the term meso-scale production. This manual will briefly describe the biology of Acartia tonsa Dana that is relevant to culture, the culture methodology for meso-scale production of their eggs and nauplii, the system components utilized in production, and how to construct a few simple tools useful for this scale of production. Commercial production of copepods requires much greater feed production than is described, or the development of an efficient artificial feed, and, therefore, is not the focus of this manual. (PDF conatains 29 pages.

    Optical gradation for crushed limestone aggregates

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    The strength and durability of asphalt pavement is directly affected by the characteristics of its main ingredient, mineral aggregate. Besides material strength, research has shown that mixture properties such as particle shape and mixture gradation have a significant affect on the quality of the asphalt concrete. A standard called Superpave has been developed which sets forth specifications for material selection and methods for measurement of aggregate properties. These standards require monitoring of aggregate properties, particularly gradation. In this dissertation, the feasibility of developing an optically based method for determining aggregate gradation was explored. The physical system primarily consists of a standard monochrome CCD video camera and a computer with a frame grabber board. Software was developed to separate touching or overlapping particles in the image, and to detect the size and shape of each particle. Correlation to estimate each particle\u27s mass and to predict the sieving behavior for crushed limestone aggregates was developed and tested. Laboratory testing demonstrated the ability to measure gradation over a range of particle sizes from 4.75 mm to 25 mm with an accuracy of +/-3 in terms of percent-passing residual when compared with mechanical sieving

    The I/O Complexity of Computing Prime Tables

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    International audienceWe revisit classical sieves for computing primes and analyze their performance in the external-memory model. Most prior sieves are analyzed in the RAM model, where the focus is on minimizing both the total number of operations and the size of the working set. The hope is that if the working set fits in RAM, then the sieve will have good I/O performance, though such an outcome is by no means guaranteed by a small working-set size. We analyze our algorithms directly in terms of I/Os and operations. In the external-memory model, permutation can be the most expensive aspect of sieving, in contrast to the RAM model, where permutations are trivial. We show how to implement classical sieves so that they have both good I/O performance and good RAM performance, even when the problem size N becomes huge—even superpolynomially larger than RAM. Towards this goal, we give two I/O-efficient priority queues that are optimized for the operations incurred by these sieves
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