A new hybrid FPGA with nanoscale clusters and CMOS routing

Author(s):  
R.M.P. Rad ◽  
M. Tehranipoor
2014 ◽  
Vol 03 (01) ◽  
pp. 1450002 ◽  
Author(s):  
J. KOCZ ◽  
L. J. GREENHILL ◽  
B. R. BARSDELL ◽  
G. BERNARDI ◽  
A. JAMESON ◽  
...  

Radio astronomical imaging arrays comprising large numbers of antennas, O(102–103), have posed a signal processing challenge because of the required O (N2) cross correlation of signals from each antenna and requisite signal routing. This motivated the implementation of a Packetized Correlator architecture that applies Field Programmable Gate Arrays (FPGAs) to the O (N) "F-stage" transforming time domain to frequency domain data, and Graphics Processing Units (GPUs) to the O (N2) "X-stage" performing an outer product among spectra for each antenna. The design is readily scalable to at least O(103) antennas. Fringes, visibility amplitudes and sky image results obtained during field testing are presented.


2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Lindsay A. Wills ◽  
Xiaohui Qu ◽  
I-Ya Chang ◽  
Thomas J. L. Mustard ◽  
Douglas A. Keszler ◽  
...  

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 447 ◽  
Author(s):  
Kyle Wm. Hall ◽  
Timothy W. Sirk ◽  
Simona Percec ◽  
Michael L. Klein ◽  
Wataru Shinoda

This study demonstrates that monodisperse entangled polymer melts crystallize via the formation of nanoscale nascent polymer crystals (i.e., nuclei) that exhibit substantial variability in terms of their constituent crystalline polymer chain segments (stems). More specifically, large-scale coarse-grain molecular simulations are used to quantify the evolution of stem length distributions and their properties during the formation of polymer nuclei in supercooled prototypical polyethylene melts. Stems can adopt a range of lengths within an individual nucleus (e.g., ∼1–10 nm) while two nuclei of comparable size can have markedly different stem distributions. As such, the attainment of chemically monodisperse polymer specimens is not sufficient to achieve physical uniformity and consistency. Furthermore, stem length distributions and their evolution indicate that polymer crystal nucleation (i.e., the initial emergence of a nascent crystal) is phenomenologically distinct from crystal growth. These results highlight that the tailoring of polymeric materials requires strategies for controlling polymer crystal nucleation and growth at the nanoscale.


Author(s):  
C. Góngora-Martín ◽  
A. Castillo-Atoche ◽  
J. Estrada-López ◽  
J. Vázquez-Castillo ◽  
J. Ortegón-Aguilar ◽  
...  

2020 ◽  
Author(s):  
Tyler Blum ◽  
Chloe Bonamici ◽  
John Valley

<p>Uranium-Lead dating of zircon remains one of the most widely utilized and most reliable temporal records throughout Earth history. This stems from the mineral’s widespread occurrence, pristine zircon being both physically and chemically robust, and the ability to evaluate the presence of open system behavior (i.e. “concordance”) through comparison of the independent <sup>238</sup>U→<sup>206</sup>Pb, <sup>235</sup>U→<sup>207</sup>Pb, and <sup>232</sup>Th→<sup>208</sup>Pb decay chains. The phenomenon of discordance is well documented in zircon, and is typically (though not always) associated with radiation damage accumulation and Pb-loss. Despite a long history of research, the nanoscale controls on Pb mobility and Pb loss (i.e. the relative rates of radiation damage, annealing, and Pb diffusion) remain poorly defined. The unique characterization capabilities of atom probe tomography (APT) provide a novel means to study U-Pb systematics on the scale of the radiation damage, annealing and diffusion processes. APT studies have documented nanoscale heterogeneity in trace elements, Pb, and Pb isotope ratios, and correlated the <sup>207</sup>Pb/<sup>206</sup>Pb ratios within clusters to transient thermal episodes in the history of a zircon.</p><p> </p><p>This work seeks to provide a foundation for multi-scale U-Pb characterization, including how differential Pb mobility at the nanoscale can influence micron- to- grain-scale U-Pb systematics. Historically, concordia diagrams have used simple Pb-loss models to extract temporal information about the timing of Pb mobility/loss; however, these models assume <sup>207</sup>Pb and <sup>206</sup>Pb are uniformly disturbed within a grain and lost in equal proportions at the time of Pb loss. Our previous studies suggest that radiogenic Pb can be concentrated and immobilized in nanoscale clusters, leading to differential retention of Pb in clusters vs. matrix domains, and requiring a more complex treatment of isotopic shifts during any post-clustering Pb loss. This “multi-domain element (Pb) mobility” (MDEM or MDPM) influences subsequent Pb-loss trajectories on concordia diagrams, manifesting in systematic offsets for discordia as a function of the zircon crystallization age, the timing of cluster formation, and the timing of Pb mobility. These results highlight that (1) traditional interpretations of discordia in the presence of cryptic nanoscale clustering can lead to inaccuracies, and (2) multi-scale U-Pb characterization offers a means to both study discordance and to extract additional temporal information from zircon with otherwise ambiguous and/or complex Pb-loss patterns.</p>


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