Evolvable Hardware

Sekanina, Lukáš

doi:10.1007/978-3-540-92910-9_50

Cited by 18 publications

(5 citation statements)

References 91 publications

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“…The distribution of the times of particle release, for which the synchrones' position angles match exactly the measured orientations, have shown a sharp concentration in time, with a random scatter of less than ±0.4 day, providing evidence that the spine tail was indeed a product of a major, fairly brief outburst (or a rapid sequence of outbursts) that peaked on December 17.6±0.2 UT, about 1.6 days after perihelion; the comet was then 0.144 ± 0.012 AU from the Sun. (For a preliminary report, see Sekanina 2012.) The predicted variations of the spine tail until mid-February 2012 are displayed in Fig.…”

Section: Early Postperihelion Observations From Ground and Sudden Trmentioning

confidence: 99%

Comet C/2011 W3 (Lovejoy): Orbit Determination, Outbursts, Disintegration of Nucleus, Dust-Tail Morphology, and Relationship to New Cluster of Bright Sungrazers

Sekanina

Chodas

2012

ApJ

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We describe the physical and orbital properties of C/2011 W3. After surviving the perihelion passage, the comet was observed to undergo major physical changes. The permanent loss of the nuclear condensation and the formation of a narrow spine tail was observed first at Malargue, Argentina, on December 20 and then systematically at Siding Spring, Australia. The process of disintegration culminated with an outburst (terminal fragmentation event) on December 17.6 UT. The postperihelion tail, observed for ∼3 months, was the product of activity over <2 days. Because of the delayed response to the hostile environment in the immediate proximity of the Sun, the nucleus' breakup and crumbling was probably caused by thermal stress due to the penetration of intense heat pulse deep into the nucleus' interior after perihelion. The same mechanism may be responsible for cascading fragmentation of sungrazers at large heliocentric distances. The observed behavior is at odds with the rubble-pile model, since the residual mass of the nucleus after perihelion, estimated at ∼10 12 g (a sphere ∼150-200 m across), still possessed significant cohesive strength. The spine tail -the product of the terminal outburst -was a synchronic feature, whose brightest part contained submillimeter-sized dust particles, released at velocities not exceeding 30 m s −1 . The loss of the nuclear condensation prevented an accurate orbital-period determination by traditional techniques. Since the missing nucleus must have been located on the synchrone, whose orientation and sunward tip have been measured, we compute the astrometric positions of this missing nucleus as the coordinates of the points of intersection of the spine tail's axis with the lines of forced orbital-period variation, derived from the orbital solutions based on high-quality preperihelion astrometry from the ground. The resulting orbit gives 698 ± 2 years for the osculating orbital period, which proves that C/2011 W3 is the first major member of the expected new, 21st-century cluster of bright Kreutz-system sungrazers, whose existence was predicted by these authors in 2007. From the spine tail's evolution, we determine that its measured tip, populated by dust particles 1-2 mm in diameter, receded antisunward from the computed position of the missing nucleus. The bizarre appearance of the comet's dust tail in images taken only hours after perihelion with the coronagraphs on board the SOHO and STEREO spacecraft is readily understood. The disconnection of the comet's head from the tail released before perihelion and an apparent activity attenuation near perihelion have a common cause -sublimation of all dust at heliocentric distances smaller than about 1.8 solar radii. The tail's brightness is strongly affected by forward scattering of sunlight by dust. From an initially broad range of particle sizes, the grains that were imaged the longest had a radiation-pressure parameter β ≃ 0.6, diagnostic of submicron-sized silicate grains and consistent with the existence of the dust-free zone around ...

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Section: Early Postperihelion Observations From Ground and Sudden Trmentioning

confidence: 99%

Comet C/2011 W3 (Lovejoy): Orbit Determination, Outbursts, Disintegration of Nucleus, Dust-Tail Morphology, and Relationship to New Cluster of Bright Sungrazers

Sekanina

Chodas

2012

ApJ

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“…Commonly used multiple-output functions for the evaluation and comparison of graph-based GP models and corresponding operators are arithmetic functions such as the digital adder and multiplier as well as combinational functions [1,8,12,29]. Since a large part of Boolean functions can be implemented as digital circuits a real-world application of graph-based GP is located in the field of evolvable hardware [28]. This type of application poses the requirement on GP systems to be able to synthesize combinational circuits from scratch which has been considered to be a challenging task for graph-based GP [30].…”

Section: Learning Of Boolean Functions With Known Input-output Mappingmentioning

confidence: 99%

Towards a General Boolean Function Benchmark Suite

Kalkreuth¹,

Vašíček

Husa

et al. 2023

Proceedings of the Companion Conference on Genetic and Evolutionary Computation

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over a decade ago, the first comprehensive review on the state of benchmarking in Genetic Programming (GP) analyzed the mismatch between the problems that are used to test the performance of GP systems and real-world problems. Since then, several benchmark suites in major GP problem domains have been proposed over time, which were able to fill some of the major gaps. In the framework of the first review about the state of benchmarking in GP, logic synthesis was classified as one of the major GP problem domains. However, a diverse and accessible benchmark suite for logic synthesis is still missing in the field of GP. In this work, we take a first step towards a benchmark suite for logic synthesis that covers different types of Boolean functions that are commonly used for the evaluation of GP systems. We also present baseline results that have been obtained by former work and in our evaluation experiments by using Cartesian Genetic Programming.

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“…This subsection contains a survey of works and a discussion on architectural issues regarding evolvable systems in FPGAs using internal (either virtual or native) reconfiguration, with a focus on the different DPR techniques used along the years. Deeper surveys that also consider external reconfiguration in FPGAs, evolution on other devices and extrinsic EHW, i.e., when evolution is performed in a simulator of the target technology, can be found within the relevant literature of the field [17,47,18,15,16,34,29]. During the first 2000s Xilinx introduced the internal configuration access port (ICAP) [2] which enabled native self-reconfiguration by providing a way to trigger reconfiguration from inside the FPGA.…”

Section: Review Of Fpga-based Evolvable Systemsmentioning

confidence: 99%

On the scalability of evolvable hardware architectures: comparison of systolic array and Cartesian genetic programming

Mora

Salvador

Torre

2018

Genet Program Evolvable Mach

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Evolvable hardware allows generating circuits adapted to specific problems by using an evolutionary algorithm (EA). Dynamic partial reconfiguration of FPGA LUTs allows making the processing elements (PEs) of these circuits small and compact, thus allowing large scale circuits to be implemented in a small FPGA area. This facilitates the use of these techniques in embedded systems with limited resources.The improvement on resource-efficient implementation techniques has allowed increasing the size of processing architectures from a few PEs to several hundreds. However, these large sizes pose new challenges for the EA and the architecture, which may not be able to take full advantage of the computing capabilities of its PEs.In this article, two different topologies-systolic array (SA) and Cartesian genetic programming (CGP)-are scaled from small to large sizes and analyzed, comparing their behavior and efficiency at different sizes. Additionally, improvements on SA connectivity are studied.Experimental results show that, in general, SA is considerably more resource-efficient than CGP, needing up to 60% fewer FPGA resources (LUTs) for a solution with similar performance, since the LUT usage per PE is 5 times smaller. Specifically, 10×10 SA has better performance than 5×10 CGP, but uses 50% fewer resources.

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Evolvable Hardware

Cited by 18 publications

References 91 publications

Comet C/2011 W3 (Lovejoy): Orbit Determination, Outbursts, Disintegration of Nucleus, Dust-Tail Morphology, and Relationship to New Cluster of Bright Sungrazers

Comet C/2011 W3 (Lovejoy): Orbit Determination, Outbursts, Disintegration of Nucleus, Dust-Tail Morphology, and Relationship to New Cluster of Bright Sungrazers

Towards a General Boolean Function Benchmark Suite

On the scalability of evolvable hardware architectures: comparison of systolic array and Cartesian genetic programming

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