114 research outputs found
BandMap: Application Mapping with Bandwidth Allocation forCoarse-Grained Reconfigurable Array
This paper proposes an application mapping algorithm, BandMap, for
coarse-grained reconfigurable array (CGRA), which allocates the bandwidth in PE
array according to the transferring demands of data, especially the data with
high spatial reuse, to reduce the routing PEs. To cover bandwidth allocation,
BandMap maps the data flow graphs (DFGs), abstracted from applications, by
solving the maximum independent set (MIS) on a mixture of tuple and quadruple
resource occupation conflict graph. Compared to a state-of-art BusMap work,
Bandmap can achieve reduced routing PEs with the same or even smaller
initiation interval (II)
Neutrino Physics with JUNO
The Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton multi-purposeunderground liquid scintillator detector, was proposed with the determinationof the neutrino mass hierarchy as a primary physics goal. It is also capable ofobserving neutrinos from terrestrial and extra-terrestrial sources, includingsupernova burst neutrinos, diffuse supernova neutrino background, geoneutrinos,atmospheric neutrinos, solar neutrinos, as well as exotic searches such asnucleon decays, dark matter, sterile neutrinos, etc. We present the physicsmotivations and the anticipated performance of the JUNO detector for variousproposed measurements. By detecting reactor antineutrinos from two power plantsat 53-km distance, JUNO will determine the neutrino mass hierarchy at a 3-4sigma significance with six years of running. The measurement of antineutrinospectrum will also lead to the precise determination of three out of the sixoscillation parameters to an accuracy of better than 1\%. Neutrino burst from atypical core-collapse supernova at 10 kpc would lead to ~5000inverse-beta-decay events and ~2000 all-flavor neutrino-proton elasticscattering events in JUNO. Detection of DSNB would provide valuable informationon the cosmic star-formation rate and the average core-collapsed neutrinoenergy spectrum. Geo-neutrinos can be detected in JUNO with a rate of ~400events per year, significantly improving the statistics of existing geoneutrinosamples. The JUNO detector is sensitive to several exotic searches, e.g. protondecay via the decay channel. The JUNO detector will providea unique facility to address many outstanding crucial questions in particle andastrophysics. It holds the great potential for further advancing our quest tounderstanding the fundamental properties of neutrinos, one of the buildingblocks of our Universe
Potential of Core-Collapse Supernova Neutrino Detection at JUNO
JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve
Detection of the Diffuse Supernova Neutrino Background with JUNO
As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO
Real-time Monitoring for the Next Core-Collapse Supernova in JUNO
Core-collapse supernova (CCSN) is one of the most energetic astrophysical
events in the Universe. The early and prompt detection of neutrinos before
(pre-SN) and during the SN burst is a unique opportunity to realize the
multi-messenger observation of the CCSN events. In this work, we describe the
monitoring concept and present the sensitivity of the system to the pre-SN and
SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is
a 20 kton liquid scintillator detector under construction in South China. The
real-time monitoring system is designed with both the prompt monitors on the
electronic board and online monitors at the data acquisition stage, in order to
ensure both the alert speed and alert coverage of progenitor stars. By assuming
a false alert rate of 1 per year, this monitoring system can be sensitive to
the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos
up to about 370 (360) kpc for a progenitor mass of 30 for the case
of normal (inverted) mass ordering. The pointing ability of the CCSN is
evaluated by using the accumulated event anisotropy of the inverse beta decay
interactions from pre-SN or SN neutrinos, which, along with the early alert,
can play important roles for the followup multi-messenger observations of the
next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure
NOVEL PLATINUM COMPLEXES SUPPORTED BY SULFONATED CNN PINCER LIGANDS RELEVANT TO AEROBIC METHANE FUNCTIONALIZATION CHEMISTRY
Mild and selective aerobic methane functionalization has always been a challenge. Shilov developed a PtII based system that has a potential to solve the problem, but the non-practical PtIV oxidant needs to be substituted by more accessible oxidants, such as O2. On pursuing this goal, several series of PtII and PtIV methyl complexes derived from two pre-ligands, Ph-dpms [(6-phenylpyridin-2-yl)(pyridin-2-yl)methanesulfonate, HL1-] and Ph-pcpps [7-(6-phenylpyridin-2-yl)-6,7-dihydro-5H-cyclopenta[b]pyridine-7-sulfonate, HL2-] were synthesized. Their reactivity in O2 and X-H (X = C, Si) bond activation (PtIIMe), and in CH3-X (X = O, N, C) reductive elimination (PtIVMe), was studied. The three steps of the proposed catalytic cycle suitable for aerobic methane functionalization were investigated.The reverse of the first step, methane C-H activation, was probed by reacting K[(L1)PtIIMe] with acid H(Et2O)2BArF4 {BArF4 = tetrakis[3,5-
bis(trifluoromethyl)phenyl]borate} in CH2Cl2 at -78 °C. Although methane and no stable PtIV(Me)H species were detected at both -78 °C and room temperature, the resulting solutions were shown to activate Si-H bonds of Et3SiH and Me3SiH to form Pt hydrido complexes.
The second step, aerobic oxidation of PtIIMe complexes, was investigated using K[(L1)PtIIMe] and K[(L2)PtIIMe].
K[(L1)PtIIMe] reacts with O2 in MeOH solutions to form diastereomeric (L1)PtIVMe2 complexes, which are barely reactive in CH3-X reductive elimination. Notably, K[(L2)PtIIMe] reacted with O2 in MeOH or acetone / TFE to selectively form three out of four possible diastereomeric (L2)PtIV(Me)OH complexes with (L2)PtIVMe2 as a minor by-product. The remaining fourth diastereomer of (L2)PtIV(Me)OH was prepared using H2O2 as oxidant.
The third step, CH3-X reductive elimination, was studied using a series of PtIVMe species supported by L1 and L2. The PtIVMe(Y) species (Y = Cl, I, OCH2CF3, OH) having methyl trans- to sulfonate and one (L2)PtIV(Me)OH complex having pyridyl trans- to methyl demonstrated facile CH3-X reductive elimination (X = Me2SO+, OH, O2CCF3, and Me2NPh+) using the corresponding nucleophiles with yields of the CH3-X products up to 99%. Two other (L2)PtIV(Me)OH complexes having methyl ligand trans- to pyridyl formed predominantly C-C coupling products in aqueous DMSO solutions of CF3CO2H.
Overall, this work demonstrates the potential of our novel sulfonated pincer ligands to support aerobic functionalization of methane at a Pt center
High-Temperature Failure Evolution Analysis of K-Type Film Thermocouples
Ni90%Cr10% and Ni97%Si3% thin-film thermocouples (TFTCs) were fabricated on a silicon substrate using magnetron sputtering technology. Static calibration yielded a Seebeck coefficient of 23.00 μV/°C. During staged temperature elevation of the TFTCs while continuously monitoring their thermoelectric output, a rapid decline in thermoelectric potential was observed upon the hot junction reaching 600 °C; the device had failed. Through three cycles of repetitive static calibration tests ranging from room temperature to 500 °C, it was observed that the thermoelectric performance of the TFTCs deteriorated as the testing progressed. Utilizing the same methodology, Ni-Cr and Ni-Si thin films corresponding to the positive and negative electrodes of the TFTCs were prepared. Their resistivity after undergoing various temperature annealing treatments was measured. Additionally, their surfaces were characterized using Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). The causes behind the decline in thermoelectric performance at elevated temperatures were analyzed from both chemical composition and microstructural perspectives
Oxidation of Methylplatinum(II) Complexes K[(L)Pt<sup>II</sup>Me] with O<sub>2</sub> and C(sp<sup>3</sup>)‑X (X = O and C) Reductive Elimination Reactivity of Methylplatinum(IV) Products (<i>L</i>)Pt<sup>IV</sup>Me(OH): The Effect of Structure of Sulfonated CNN-Pincer Ligands L
Two sulfonated CNN-pincer ligands L1 and L2 were used
to explore
the oxidative functionalization of the PtII-Me bond in
derived K[(L)PtIIMe] complexes (L = L1 and L2) using O2 and H2O2 as oxidants (HL1– = (6-phenylpyrid-2-yl)(pyrid-2-yl)methanesulfonate; HL2– = (6-phenylpyrid-2-yl)-6,7-dihydro-5H-cyclopenta [b]pyridine-7-sulfonate). Oxidation with O2 of K[(L1)PtIIMe] in MeOH produced a single high-valent platinum complex,
(L1)PtIVMe2, whereas the use of H2O2 led to (L1)PtIVMe(OH), 10c,
and (L1)2PtIV2Me2(μ-OH)2, 14, having different configurations of a PtIV center. Oxidation of a more rigid analog, K[(L2)PtIIMe], with O2 led to diastereomeric complexes (L2)PtIVMe(OH), 11d, in MeOH and 11a (detected
as an adduct with the CF3CH2O– anion) in acetone/2,2,2-trifluoroethanol mixtures. The use of H2O2 led to (L2)PtIVMe(OH), 11c, and (L2)2PtIV2Me2(μ-OH)2, 15, the analogs of 10c and 14, respectively. When heated with CF3CO2H in aqueous DMSO, MeOH, or acetone at 80 °C, (L)PtIVMe(OH) complexes produced in high yield either MeOH and MeO2CCF3 or C(sp2)-C(sp3) coupled products
involving a carbon atom of pincer ligands. DFT calculations were used
to analyze the observed reactivity. It was concluded that the key
factors favoring the C(sp3)-O coupling are the trans-arrangement of the methyl ligand and the sulfonate
group, the use of CF3CO2– as
an O-nucleophile and DMSO as a solvent favoring the generation of
highly electrophilic PtIVMe intermediates
Size-Dependent Magnetic, Photoabsorbing, and Photocatalytic Properties of Single-Crystalline Bi 2
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