69 research outputs found
Upgrading the quality of recycled aggregates from construction and demolitionwaste by using a novel brick separation and surface treatment method
Mixed recycled aggregates (MRA) from construction and demolition waste (CDW) with high-purity and environmental performance are required for highway construction application in base layer and precast concrete curbs. The main problematic constituents that reduce the quality level of the recycled aggregates applications are brick components, flaky particles, and attached mortar, which make up a large proportion of CDW in some countries. This paper studies the potential of brick separation technology based on shape characteristics in order to increase the recycled concrete aggregates (RCA) purity for MRA quality improvement. MRA after purification was also processed with surface treatment experiment by rotating in a cylinder to improve the shape characteristics and to remove the attached mortar. The purity, strength property, densities, water absorption ratio, shape index, and mortar removal ratio of MRA were studied before and after the use of the brick separation and surface treatment proposed in this study. Finally, the recycled aggregates upgradation solution was adopted in a stationary recycling plant designed for a length of 113 km highway construction. The properties of CDW mixed concrete for precast curbs manufacturing were conducted. The results indicate that problematic fractions (brick components, particle shape, and surface weakness) in the MRA were significantly reduced by using brick separation and surface treatment solution. Above all, it is very important that the proposed brick separation method was verified to be practically adopted in CDW recycling plant for highway base layer construction and concrete curbs manufacturing at a low cost
BUMP: A Benchmark of Unfaithful Minimal Pairs for Meta-Evaluation of Faithfulness Metrics
The proliferation of automatic faithfulness metrics for summarization has
produced a need for benchmarks to evaluate them. While existing benchmarks
measure the correlation with human judgements of faithfulness on
model-generated summaries, they are insufficient for diagnosing whether metrics
are: 1) consistent, i.e., indicate lower faithfulness as errors are introduced
into a summary, 2) effective on human-written texts, and 3) sensitive to
different error types (as summaries can contain multiple errors). To address
these needs, we present a benchmark of unfaithful minimal pairs (BUMP), a
dataset of 889 human-written, minimally different summary pairs, where a single
error is introduced to a summary from the CNN/DailyMail dataset to produce an
unfaithful summary. We find BUMP complements existing benchmarks in a number of
ways: 1) the summaries in BUMP are harder to discriminate and less probable
under SOTA summarization models, 2) unlike non-pair-based datasets, BUMP can be
used to measure the consistency of metrics, and reveals that the most
discriminative metrics tend not to be the most consistent, and 3) unlike
datasets containing generated summaries with multiple errors, BUMP enables the
measurement of metrics' performance on individual error types.Comment: Accepted as a long main conference paper at ACL 202
Mechanism Analysis of Spalling Defect on Rail Surface under Rolling Contact Conditions
Under the wheel/rail contact loading conditions, the microcracks on the rail surface propagate, leading to spalling defect or rail fracture and threatening the travelling safety of high-speed railway directly. In order to analyze the mechanism of the crack propagation on the rail surface, the calculation model of the wheel/rail contact fatigue was established, and the variation of the stress intensity factor at the crack tip when the crack length was increased from 0.1 mm to 2 mm was obtained. Based on the mixed-mode fracture criterion and Paris growth theory, the mechanism of the crack propagation on the rail surface was analyzed. The results show that when the microcrack grows to macrocrack, the mode of the fatigue crack on the rail surface is mixed including sliding mode and open mode. With the increase of the crack length, the stress intensity factor KI increases first and then decreases gradually, and the relative dangerous location of the open-mode crack moves from the inner edge of the contact area to the outer edge, while the factor KII is increasing during the whole propagation process, and the relative dangerous location of the sliding-mode crack remains unchanged basically. The main failure mode of crack is open during the initial stage and then transforms into sliding mode with the crack length increasing. The crack tends to propagate upward and leads to spalling defect when the crack length is between 0.3 and 0.5 mm. This propagation path is basically identical with the spalling path of the service rail. The research results will provide a basis for improving the antifatigue performance of rail and establishing the grinding procedure
Effects of Pressure and Doping on Ruddlesden-Popper phases Lan+1NinO3n+1
Recently the discovery of superconductivity with a critical temperature Tc up
to 80 K in Ruddlesden-Popper phases Lan+1NinO3n+1 (n = 2) under pressure has
garnered considerable attention. Up to now, the superconductivity was only
observed in La3Ni2O7 single crystal grown with the optical-image floating zone
furnace under oxygen pressure. It remains to be understood the effect of
chemical doping on superconducting La3Ni2O7 as well as other Ruddlesden-Popper
phases. Here, we systematically investigate the effect of external pressure and
chemical doping on polycrystalline Ruddlesden-Popper phases. Our results
demonstrate the application of pressure and doping effectively tunes the
transport properties of Ruddlesden-Popper phases. We find pressure-induced
superconductivity up to 86 K in La3Ni2O7 polycrystalline sample, while no
signatures of superconductivity are observed in La2NiO4 and La4Ni3O10 systems
under high pressure up to 50 GPa. Our study sheds light on the exploration of
high-Tc superconductivity in nickelates.Comment: 21 papes, 8 figures and 1 tabl
Research on the development and testing methods of physical education and agility training equipment in universities
IntroductionBecause of the problems of insufficient funds and traditional training methods in college sports agile training, an agile training system based on a wireless ad hoc network was developed to evaluate the effect of improving the sensitive quality of ordinary college students. Based on the ESP-MESH network, the lower computer realizes automatic networking between devices and tests the performance of the mesh network. Fourteen male college students received 9 weeks of agility training, with seven students in each of two groups: traditional agility training and agile equipment training. The researchers evaluated the performance of both groups in rapid disguise, body coordination, changing movements, and predictive decision-making.ResultsThere was no significant difference between the groups before training, but there were significant differences in the four abilities after training (p < 0.01). The experimental group had significant differences in rapid direction change and physical coordination (p < 0.05), and in changing movement and predictive decision-making ability (p < 0.01).ConclusionBoth traditional training and agile equipment training improve the agility quality of college students, and the latter shows better results in certain abilities. However, limited by other physical qualities, the improvement of motor changes and predictive decision-making ability is not as obvious as the other two abilities
Symptoms of anxiety and depression associated with steroid efficacy and clinical outcomes in patients with inflammatory bowel disease
BackgroundAnxiety and depression symptoms are very common in patients with inflammatory bowel disease (IBD). We aimed to explore the impact of anxiety and depression on the efficacy of medications, as well as IBD-related poor outcomes.MethodThis was a prospective longitudinal observational study. Hospital Anxiety and Depression Scale was used to assess anxiety and depression symptoms. Logistic regression analyses were used to assess the association between anxiety/depression and the response to different medications. Kaplan–Meier survival analysis and Cox regression model were applied to analyze the relationship between anxiety/depression and IBD-related poor outcomes, which were defined as urgent IBD-related hospitalization, IBD-related surgery, or death.ResultsA total of 325 IBD patients were enrolled, 118 of whom were treated with corticosteroids, 88 with azathioprine/6-mercaptopurine (AZA/6-MP), and 147 with anti-TNF agents. Anxiety/depression symptoms were found to be significantly related to steroid resistance, but independent of AZA/6-MP and anti-TNF agents nonresponse. There was a significant association between anxiety/depression symptoms and IBD-related poor outcomes. Coexisting with anxiety/depression symptoms was an independent influencing factor of steroid resistance and IBD-related poor outcomes.ConclusionIBD patients with anxiety/depression symptoms were at a higher risk of developing steroid resistance and IBD-related poor outcomes. Future studies are needed to explore whether interventions for anxiety and depression will improve their response to medications and change their prognosis
Superconductivity in trilayer nickelate La4Ni3O10 under pressure
Nickelates gained a great deal of attention due to their similar crystal and
electronic structures of cuprates over the past few decades. Recently,
superconductivity with transition temperature exceeding liquid-nitrogen
temperature is discovered in La3Ni2O7, which belong to the Ruddlesden-Popper
(RP) phases Lan+1NinO3n+1 with n = 2. In this work, we go further and find
pressure-induced superconductivity in another RP phase La4Ni3O10 (n = 3) single
crystals. Our angle-resolved photoemission spectroscopy (ARPES) experiment
suggest that the electronic structure of La4Ni3O10 is very similar to that of
La3Ni2O7. We find that the density-wave like anomaly in resistivity is
progressively suppressed with increasing pressure. A typical phase diagram is
obtained with the maximum Tc of 21 Kelvin. Our study sheds light on the
exploration of unconventional superconductivity in nickelates.Comment: 16 pages, 5 figure
Pressure-induced Superconductivity and Structure Phase Transition in SnAs-based Zintl Compound SrSn2As2
Layered SnAs-based Zintl compounds exhibit a distinctive electronic
structure, igniting extensive research efforts in areas of superconductivity,
topological insulators and quantum magnetism. In this paper, we systematically
investigate the crystal structures and electronic properties of the Zintl
compound SrSn2As2 under high-pressure. At approximately 20.8 GPa,
pressure-induced superconductivity is observed in SrSn2As2 with a
characteristic dome-like evolution of Tc. Theoretical calculations together
with high pressure synchrotron X-ray diffraction and Raman spectroscopy have
identified that SrSn2As2 undergoes a structural transformation from a trigonal
to a monoclinic structure. Beyond 28.3 GPa, the superconducting transition
temperature is suppressed due to a reduction of the density of state at the
Fermi level. The discovery of pressure-induced superconductivity, accompanied
by structural transitions in SrSn2As2, greatly expands the physical properties
of layered SnAs-based compounds and provides a new ground states upon
compression.Comment: 15 pages, 6 figures. arXiv admin note: text overlap with
arXiv:2307.1562
- …