109 research outputs found
Search for neutrino emission from the Cygnus Bubble based on LHAASO -ray observations
The Cygnus region, which contains massive molecular and atomic clouds and
young stars, is a promising Galactic neutrino source candidate. Cosmic rays
transport in the region can produce neutrinos and -rays. Recently, the
Large High Altitude Air Shower Observatory (LHAASO) detected an
ultrahigh-energy -ray bubble (Cygnus Bubble) in this region. Using
publicly available track events detected by the IceCube Neutrino Observatory in
7 years of full detector operation, we conduct searches for correlated neutrino
signals from the Cygnus Bubble with neutrino emission templates based on LHAASO
-ray observations. No significant signals were found for any employed
templates. With the 7 TeV -ray flux template, we set a flux upper limit
of 90% confidence level (C.L.) for the neutrino emission from the Cygnus Bubble
to be at
5 TeV
Searching for neutrino emissions from multi-frequency sources
Pinpointing the neutrino sources is crucial to unveil the mystery of
high-energy cosmic rays. The search for neutrino-source candidates from
coincident neutrino-photon signatures and electromagnetic objects with peculiar
flaring behaviors have the potential to increase our chances of finding
neutrino emitters. In this paper, we first study the temporal correlations of
astrophysical flares with neutrinos, considering a few hundreds of
multi-frequency sources from ALMA, WISE, Swift, and Fermi in the containment
regions of IceCube high-energy alerts. Furthermore, the spatial correlations
between blazars and neutrinos are investigated using the subset of 10-year
IceCube track-like neutrinos with around 250 thousand events. In the second
test, we account for 2700 blazars with different types of flaring phases in
addition to sole position. No significant neutrino emissions were found from
our analyses. Our results indicate an interesting trend showing the infrared
flaring stages of WISE blazars might be correlated with arrival times of the
neutrino alerts. Possible overflow of neutrinos associated with two of our
blazar sub-samples are also illustrated. One is characterized by a significant
flaring lag in infrared with respect to gamma-rays, like seen for TXS0506+056,
and the other is characterized by highly simultaneous infrared and gamma-ray
flares. These phenomena suggest the need to improve current multi-frequency
light-curve catalogs to pair with the advent of more sensitive neutrino
observatories.Comment: 30 pages, 18 figure
Seismic loss assessment for buildings with multiple LOD BIM data
Earthquake-induced economic loss of buildings is a fundamental concern for earthquake-resilient cities. The FEMA P-58 method is a state-of-the-art seismic loss assessment method for buildings. Nevertheless, because the FEMA P-58 method is a refined component-level loss assessment method, it requires highly detailed data as the input. Consequently, the knowledge of building details will affect the seismic loss assessment. In this study, a seismic loss assessment approach for buildings combining building information modeling (BIM) with the FEMA P-58 method is proposed. The detailed building data are automatically obtained from the building information model in which the building components may have different levels of development (LODs). The determination of component type and the development of the component vulnerability function when the information is incomplete are proposed. Finally, to demonstrate the rationality of the proposed method, an office building that is available online is selected, and the seismic loss assessments with multi-LOD BIM data are performed as case studies. The results show that, on the one hand, even if the available building information is limited, the proposed method can still produce an acceptable loss assessmenton the other hand, given more information, the accuracy of the assessment can be improved and the uncertainty can be reduced using the proposed method.The study is financial supported by the National Natural Science Foundation of China (No. 51578320)
Impacts of renewable portfolio standard on carbon emission peaking and tradable green certificate market: A system dynamics analysis method
With the announcement of the carbon peaking and carbon neutrality target in China as well as the launch of the nationwide green power renewable generation trading, one of the key issues is how to design an effective renewable portfolio standard (RPS) and build an efficient tradable green certificate (TGC) market. The quota that stipulates the share of electricity supplied from qualified renewable energy (RE) sources has substantial impacts on the TGC market, the electricity market, and the occurred time of carbon emission peaking. However, few studies have been reported on effectively quantifying the impacts of quota variation. Given this background, this paper presents an innovative system dynamics (SD) model to evaluate the impacts of quota variation on the trading results of the TGC market and the trend of carbon emissions in China for the next decade. The proposed SD model takes factors such as the accommodating capability by the power system for RE generation, the policy-driven carbon emission reduction target as well as the decreasing fixed feed-in tariff (FIT) for RE generation as constraints for the first time. These factors are quantified in the constraints based on the current RE policies and market trading mechanism in China to improve the evaluation accuracy of the SD model. Using real-world data, simulations under various scenarios are carried out to validate the feasibility and efficiency of the proposed model. The methods for further improving the design of TGC market are also further explored, which are expected to effectively guide China to achieve the carbon peaking target
A Transition Mechanism for the Participation of Renewable Energy Generation Companies in Competitive Electricity Spot Markets
Under the Chinaās ādual carbonā national goalāreaching peak carbon emissions by 2030 and achieving carbon neutrality by 2060, one of the key issues in China is how to smoothly transit from a fixed-price mode to a competitive market pricing mode for renewable energy generation companies. Aiming at minimizing governmental subsidies and maximizing the fairness among renewable energy generation companies, a multi-agent three-layer transition mechanism with the transactions of green certificates considered is proposed in this paper. Through adjusting subsidy policies, the developed transition mechanism can stimulate the renewable energy generation companies to gradually participate in the competitive electricity spot market. Specifically, a multi-market multi-agent transaction framework in the transition mechanism is first established. Then, in order to derive the important parameters of the transition mechanism, a method that decouples the electricity market and the green certificate market is designed. Finally, the feasibility and efficiency of the proposed transition mechanism are demonstrated through numerical examples
A fast tunable driver of light source for the TRIDENT Pathfinder experiment
TRIDENT (The tRopIcal DEep-sea Neutrino Telescope) is a proposed
next-generation neutrino telescope to be constructed in the South China Sea. In
September 2021, the TRIDENT Pathfinder experiment (TRIDENT EXplorer, T-REX for
short) was conducted to evaluate the in-situ optical properties of seawater.
The T-REX experiment deployed three digital optical modules at a depth of 3420
meters, including a light emitter module (LEM) and two light receiver modules
(LRMs) equipped with photomultiplier tubes (PMTs) and cameras to detect light
signals. The LEM emits light in pulsing and steady modes. It features a fast
tunable driver to activate light-emitting diodes (LEDs) that emit
nanosecond-width light pulses with tunable intensity. The PMTs in the LRM
receive single photo-electron (SPE) signals with an average photon number of
approximately 0.3 per 1-microsecond time window, which is used to measure the
arrival time distribution of the SPE signals. The fast tunable driver can be
remotely controlled in real-time by the data acquisition system onboard the
research vessel, allowing for convenient adjustments to the driver's parameters
and facilitating the acquisition of high-quality experimental data. This paper
describes the requirements, design scheme, and test results of the fast tunable
driver, highlighting its successful implementation in the T-REX experiment and
its potential for future deep-sea experiments
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