Resolving Single-layer Nanosheets as Short-lived Intermediates in the Solution Synthesis of FeS
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99 GENERAL AND MISCELLANEOUS↗
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Test Results of the CERN HL-LHC low- Quadrupole Short Models MQXFS3c and MQXFS4
For the High Luminosity Upgrade of the CERN Large Hadron Collider, lower * quadrupole magnets based on advanced Nb3Sn conductors will be installed on each side of the ATLAS and CMS experiment insertion zones. As part of the technological developments needed to achieve the required field gradient of 132.6 T/m within a 150-mm aperture, short length model magnets, named MQXFS, are tested both at the CERN SM18 and FERMI Lab test facilities. The model magnets rely on two types of Nb3Sn conductors (RRP and PIT) and on an innovative bladders and keys design to provide mechanical support against the Lorentz forces. In 2016 and 2017, the powering tests of the first two models MQXFS3 (RRP) and MQXFS5 (PIT) proved that nominal performance (16.5 kA) could be reached with excellent memory of the quench current after thermal cycle. However both magnets showed a slow training behavior with clear observations of voltage disturbances before the quench. Besides MQXFS5 only could reach ultimate current (17.9 kA) whereas erratic behavior was observed on MQXFS3 due to conductor local degradation at the head of one of the coil. In 2018, this limiting coil was changed and the applied azimuthal pre-stress increased. If ultimate current could then be reached, no stable current could be maintained due to identified defect on the outer layer of the new coil. Finally the outcome of the test of the new model MQXFS4, featuring the final RRP conductors that will be used for the series production and variation on the inner layer quench heater designs are here reported in details.
43 PARTICLE ACCELERATORS↗
Short-term impacts of 2017 western North American wildfires on meteorology, the atmosphere’s energy budget, and premature mortality
Abstract Western North American fires have been increasing in magnitude and severity over the last few decades. The complex coupling of fires with the atmospheric energy budget and meteorology creates short-term feedbacks on regional weather altering the amount of pollution to which Americans are exposed. Using a combination of model simulations and observations, this study shows that the severe fires in the summer of 2017 increased atmospheric aerosol concentrations leading to a cooling of the air at the surface, reductions in sensible heat fluxes, and a lowering of the planetary boundary layer height over land. This combination of lower-boundary layer height and increased aerosol pollution from the fires reduces air quality. We estimate that from start of August to end of October 2017, ∼400 premature deaths occurred within the western US as a result of short-term exposure to elevated PM 2.5 from fire smoke. As North America confronts a warming climate with more fires the short-term climate and pollution impacts of increased fire activity should be assessed within policy aimed to minimize impacts of climate change on society.
Bernstein, Diana N. (ORCID:0000000308279336)↗
The Distant, Galaxy Cluster Environment of the Short GRB 161104A at $z\sim 0.8$ and a Comparison to the Short GRB Host Population
We present optical observations of the Swift short-duration gamma-ray burst (GRB) GRB 161104A and its host galaxy at z = 0.793 ± 0.003. We model the multiband photometry and spectroscopy with the stellar population inference code Prospector and explore the posterior using nested sampling. We find a mass-weighted age of $t_m = 2.12^{+0.23}_{-0.21}$ Gyr, stellar mass of log(M/M ⊙ ), metallicity of log(Z/Z ⊙ ), dust extinction of $A_V = 0.08^{+0.08}_{-0.05}$, and low star formation rate of 9.9 × 10 -2 M ⊙ yr -1 . These properties, along with a prominent 4000 Å break and optical absorption lines, classify this host as an early-type, quiescent galaxy. Using Dark Energy Survey galaxy catalogs, we demonstrate that the host of GRB 161104A resides on the outskirts of a galaxy cluster at z ≈ 0.8, situated ≈1 Mpc from the likely brightest cluster galaxy. We also present new modeling for 20 additional short GRB hosts (≈33% of which are early-type galaxies), finding population medians of and $t_m = 1.07^{+1.98}_{-0.67}$ Gyr (68% confidence). We further find that the host of GRB 161104A is more distant, less massive, and younger than the four other short GRB hosts known to be associated with galaxy clusters. Cluster short GRBs have faint afterglows, in the lower ≈11% (≈30%) of observed X-ray (optical) luminosities. We place a lower limit on the fraction of short GRBs in galaxy clusters versus those in the field of ≈5%–13%, consistent with the fraction of stellar mass of ≈10%–20% in galaxy clusters at redshifts 0.1 ≤ z ≤ 0.8. Future studies that take advantage of wider-field and deeper cluster surveys are needed to understand the true rate of short GRBs in clusters and their effect on heavy-element enrichment in the intracluster medium.
79 ASTRONOMY AND ASTROPHYSICS↗
Day-to-day reliability of basal heart rate and short-term and ultra short-term heart rate variability assessment by the Equivital eq02+ LifeMonitor in US Army soldiers
Introduction The present study determined the (1) day-to-day reliability of basal heart rate (HR) and HR variability (HRV) measured by the Equivital eq02+ LifeMonitor and (2) agreement of ultra short-term HRV compared with short-term HRV. Methods Twenty-three active-duty US Army Soldiers (5 females, 18 males) completed two experimental visits separated by >48 hours with restrictions consistent with basal monitoring (eg, exercise, dietary), with measurements after supine rest at minutes 20–21 (ultra short-term) and minutes 20–25 (short-term). HRV was assessed as the SD of R–R intervals (SDNN) and the square root of the mean squared differences between consecutive R–R intervals (RMSSD). Results The day-to-day reliability (intraclass correlation coefficient (ICC)) using linear-mixed model approach was good for HR (0.849, 95% CI: 0.689 to 0.933) and RMSSD (ICC: 0.823, 95% CI: 0.623 to 0.920). SDNN had moderate day-to-day reliability with greater variation (ICC: 0.689, 95% CI: 0.428 to 0.858). The reliability of RMSSD was slightly improved when considering the effect of respiration (ICC: 0.821, 95% CI: 0.672 to 0.944). There was no bias for HR measured for 1 min versus 5 min (p=0.511). For 1 min measurements versus 5 min, there was a very modest mean bias of −4 ms for SDNN and −1 ms for RMSSD (p≤0.023). Conclusion When preceded by a 20 min stabilisation period using restrictions consistent with basal monitoring and measuring respiration, military personnel can rely on the eq02+ for basal HR and RMSSD monitoring but should be more cautious using SDNN. These data also support using ultra short-term measurements when following these procedures.
General & Internal Medicine↗
Short-Term Load Forecasting Based Automatic Distribution Network Reconfiguration
In a traditional dynamic network reconfiguration study, the optimal topology is determined at every scheduled time point by using the real load data measured at that time. The development of the load forecasting technique can provide an accurate prediction of the load power that will happen in a future time and provide more information about load changes. With the inclusion of load forecasting, the optimal topology can be determined based on the predicted load conditions during a longer time period instead of using a snapshot of the load at the time when the reconfiguration happens; thus, the distribution system operator can use this information to better operate the system reconfiguration and achieve optimal solutions. This paper proposes a short-term load forecasting approach to automatically reconfigure distribution systems in a dynamic and pre-event manner. Specifically, a short-term and high-resolution distribution system load forecasting approach is proposed with a forecaster based on support vector regression and parallel parameters optimization. The network reconfiguration problem is solved by using the forecasted load continuously to determine the optimal network topology with the minimum amount of loss at the future time. The simulation results validate and evaluate the proposed approach.
24 POWER TRANSMISSION AND DISTRIBUTION↗
A Short-Term and High-Resolution System Load Forecasting Approach Using Support Vector Regression with Hybrid Parameters Optimization
This work proposes an approach for distribution system load forecasting, which aims to provide highly accurate short-term load forecasting with high resolution utilizing a support vector regression (SVR) based forecaster and a two-step hybrid parameters optimization method. Specifically, because the load profiles in distribution systems contain abrupt deviations, a data normalization is designed as the pretreatment for the collected historical load data. Then an SVR model is trained by the load data to forecast the future load. For better performance of SVR, a two-step hybrid optimization algorithm is proposed to determine the best parameters. In the first step of the hybrid optimization algorithm, a designed grid traverse algorithm (GTA) is used to narrow the parameters searching area from a global to local space. In the second step, based on the result of the GTA, particle swarm optimization (PSO) is used to determine the best parameters in the local parameter space. After the best parameters are determined, the SVR model is used to forecast the short-term load deviation in the distribution system.
24 POWER TRANSMISSION AND DISTRIBUTION↗
Positive water linkages of producing short rotation poplars and willows for bioenergy and phytotechnologies
The production of short rotation woody crops (SRWCs) such as poplars and willows is a promising component of global bioenergy and phytotechnology portfolios. In addition to the provision of biomass feedstocks and pollution remediation, these trees and shrubs have been sustainably grown to conserve or utilize water in a variety of applications. Growing these woody plants for multiple uses supports many of the United Nation's Sustainable Development Goals (SDGs), especially Clean Water and Sanitation (SDG6) and Affordable and Clean Energy (SDG7). As a result, focusing on ecosystem services such as freshwater and biomass has become an important aspect of deploying these production systems across variable landscapes. The current review consists of an introduction of ecosystem services and the SDGs, as well as SRWCs and their applications. The middle section of the review contains case studies highlighting the positive water linkages of producing short rotation poplars and willows for bioenergy and phytotechnologies. The review concludes with a section that combines the common themes that are consistent among the case studies to address options for integrating new bioenergy feedstock production systems into rural and urban landscapes to promote environmental, social and economic sustainability. This article is categorized under: Bioenergy > Economics and Policy Bioenergy > Climate and Environment
biomass production↗
Short O–O separation in layered oxide Na 0.67 CoO 2 enables an ultrafast oxygen evolution reaction
The layered oxide Na 0.67 CoO 2 with Na + occupying trigonal prismatic sites between CoO 2 layers exhibits a remarkably high room temperature oxygen evolution reaction (OER) activity in alkaline solution. The high activity is attributed to an unusually short O–O separation that favors formation of peroxide ions by O - –O – interactions followed by O 2 evolution in preference to the conventional route through surface O–OH – species. The dependence of the onset potential on the pH of the alkaline solution was found to be consistent with the loss of H + ions from the surface oxygen to provide surface O - that may either be attacked by solution OH - or react with another O - ; a short O–O separation favors the latter route. The role of a strong hybridization of the O-2 p and low-spin Co III /Co IV π-bonding d states is also important; the OER on other Co III /Co IV oxides is compared with that on Na 0.67 CoO 2 as well as that on IrO 2 .
Wang, Hao↗
Evaluation of regression and neural network models for solar forecasting over different short-term horizons
Forecasting solar irradiation has acquired immense importance in view of the exponential increase in the number of solar pho- tovoltaic (PV) system installations. In this article, analyses results involving statistical and machine-learning techniques to predict solar irradiation for di?erent forecasting horizons are reported. Yearlong typical meteorological year 3 (TMY3) datasets from three cities in the United States with di?erent climatic conditions have been used in this analysis. A simple forecast approach that assumes consecutive days to be identical serves as a baseline model to compare forecasting alternatives. To account for seasonal variability and to capture short-term ?uctuations, di?erent variants of the lagged moving average (LMX) model with cloud cover as the input variable are evaluated. Finally, the proposed LMX model is evaluated against an arti?cial neural network (ANN) model. How the one-hour and 24-hour models can be used in conjunction to predict di?erent short-term rolling horizons is discussed, and this joint application is illustrated for a four-hour rolling horizon forecast scheme. Finally, the e?ect of using predicted cloud cover values, instead of measured ones, on the accuracy of the models is assessed. Results show that LMX models do not degrade in forecast accuracy if models are trained with the forecast cloud cover data.
Inanlouganji, Alireza↗
Mechanical Analysis of the Short Model Magnets for the Nb $_{3}$Sn Low-$\beta$ Quadrupole MQXF
During the development of MQXF, the new Nb 3 Sn quadrupole to be used in the large hadron collider (LHC) inner triplets for the High Luminosity upgrade, three short models were tested: MQXFS1, MQXFS3, and MQXFS5. These models differ in the use of thin or thick laminations for the iron components, in the coil design, and in the superconductive strands, rod restack process (RRP) or powder in tube (PIT). In the MQXF design, the azimuthal prestress is provided at room temperature by means of the bladder-key technology, and it is further increased during the cooldown by the differential thermal contraction of the various components. Four aluminum rods provide the longitudinal prestress. Both systems allow for a flexible control of the amount of prestress applied. As a consequence, it was possible to test the models exploring different azimuthal and longitudinal prestress conditions, in an attempt to understand their impact on the magnet performances. Here, this paper studies the mechanical behavior of these short models, also providing the strain and stresses measured by means of strain gauges installed on the aluminum shell, on the winding poles and on the rods. Finally, the paper compares the measures with the results from finite element (FE) models.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Magnetic structure, excitations and short-range order in honeycomb Na 2 Ni 2 TeO 6
Na 2 Ni 2 TeO 6 has a layered hexagonal structure with a honeycomb lattice constituted by Ni 2+ and a chiral charge distribution of Na + that resides between the Ni layers. In the present work, the antiferromagnetic transition temperature of Na 2 Ni 2 TeO 6 is confirmed at TN˜ 27 K, and further, it is found to be robust up to 8 T magnetic field and 1.2 GPa external pressure; and, without any frequency-dependence. Slight deviations from nominal Na-content (up to 5%) does not seem to influence the magnetic transition temperature, TN. Isothermal magnetization curves remain almost linear up to 13 T. Our analysis of neutron diffraction data shows that the magnetic structure of Na 2 Ni 2 TeO 6 is faithfully described by a model consisting of two phases described by the commensurate wave vectors vec kc, (0.5 0 0) and (0.5 0 0.5), with an additional short-range order component incorporated in to the latter phase. Consequently, a zig-zag long-range ordered magnetic phase of Ni 2+ results in the compound, mixed with a short-range ordered phase, which is supported by our specific heat data. Theoretical computations based on density functional theory (DFT) predict predominantly in-plane magnetic exchange interactions that conform to a J1-J2-J3 model with a strong J3 term. The computationally predicted parameters lead to a reliable estimate for TN and the experimentally observed zig-zag magnetic structure. A spin wave excitation in Na 2 Ni 2 TeO 6 at E ˜ 5 meV at T = 5 K is mapped out through inelastic neutron scattering experiments, which is reproduced by linear spin wave theory calculations using the J values from our computations. Our specific heat data and inelastic neutron scattering data strongly indicate the presence of short-range spin correlations, at T > TN, stemming from incipient antiferromagnetic clusters.
36 MATERIALS SCIENCE↗
RF synchronized short pulse laser ion source
A laser ion source that produces shortly bunched ion beam is proposed. In this ion source, ions are extracted immediately after the generation of laser plasma by an ultra-short pulse laser before its diffusion. The ions can be injected into radio frequency (RF) accelerating bucket of a subsequent accelerator. As a proof-of-principle experiment of the ion source, a RF resonator is prepared and H{sub 2} gas was ionized by a short pulse laser in the RF electric field in the resonator. As a result, bunched ions with 1.2 mA peak current and 5 ns pulse length were observed at the exit of RF resonator by a probe.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Emissions in short-gated ns/ps/fs-LIBS for fuel-to-air ratio measurements in methane-air flames
A study of short-gated 10 nanosecond (ns), 100 picosecond (ps), and 100 femtosecond (fs) laser induced breakdown spectroscopy (LIBS) was conducted for fuel-to-air ratio (FAR) measurements in an atmospheric Hencken flame. The intent of the work is to understand which emission lines are available near the optical range in each pulse width regime and which emission ratios may be favorable for generating equivalence ratio calibration curves. The emission spectra in the range of 550–800 nm for ns-LIBS and ps-LIBS are mostly similar with slightly elevated atomic oxygen lines by ps-LIBS. Spectra from fs-LIBS show the lowest continuum background and prominent individual atomic lines, though have significantly weaker ionic emission from nitrogen. A qualitative explanation based on assumed local thermodynamic equilibrium and electron temperatures calculated by the N I I ( 565 n m ) and N I I ( 594 n m ) emissions is presented. In studying line emission ratios for FAR calculation, it is found that H α <#comment/> ( 656 n m ) / N I I ( 568 n m ) is best for FAR measurements with ns-LIBS and remains viable for ps-LIBS, while H α <#comment/> ( 656 n m ) / O I ( 777 n m ) is optimal for the ps-LIBS and fs-LIBS cases. Due to low continuum background and short time delay for spectra collection, fs-LIBS is very promising for high-speed FAR measurements using short-gated LIBS.
Gragston, Mark (ORCID:0000000324698995)↗
Magnetospheric Truncation, Tidal Inspiral, and the Creation of Short-period and Ultra-short-period Planets
Sub-Neptunes around FGKM dwarfs are evenly distributed in log orbital period down to ∼10 days, but dwindle in number at shorter periods. Both the break at ∼10 days and the slope of the occurrence rate down to ∼1 day can be attributed to the truncation of protoplanetary disks by their host star magnetospheres at corotation. We demonstrate this by deriving planet occurrence rate profiles from empirical distributions of pre-main-sequence stellar rotation periods. Observed profiles are better reproduced when planets are distributed randomly in disks—as might be expected if planets formed in situ—rather than piled up near disk edges, as would be the case if they migrated in by disk torques. Planets can be brought from disk edges to ultra-short (<1 day) periods by asynchronous equilibrium tides raised on their stars. Tidal migration can account for how ultra-short-period planets are more widely spaced than their longer-period counterparts. Our picture provides a starting point for understanding why the sub-Neptune population drops at ∼10 days regardless of whether the host star is of type FGK or early M. We predict planet occurrence rates around A stars to also break at short periods, but at ∼1 day instead of ∼10 days because A stars rotate faster than stars with lower masses (this prediction presumes that the planetesimal building blocks of planets can drift inside the dust sublimation radius).
79 ASTRONOMY AND ASTROPHYSICS↗