arXiv subjects

Fang Yan

Publications and source records attributed to Fang Yan.

25 records · Page 2Linked to original sources

arXiv2022

Study of parity violation in $Λ_c^+\toϕp$ and $Λ_c^+ \to ωp$ decays

Evidence for CP violation in baryonic decays has not been seen in experiments. With large data events accumulated at $e^+e^-$ collider or Large Hadron Collider, the charmed baryon decays would provide a promising laboratory to test the CP symmetry. In this work, we formulate the $Λ_c^+\toϕp$ and $ Λ_c^+\toωp$ decays for the measurements of their asymmetry parameters in weak decays at the BESIII or the LHCb experiments. The polarization transfer is analyzed in the two processes of $e^+ e^- \toΛ_c^+\barΛ_c^-$ and $Λ_b^0\to Λ^+_cπ^-$, and the formulas of the joint angular distribution for these processes are provided. The sensitivity of the measurement of asymmetry parameters for the above two decay processes is estimated for the future experiments.

hep-ph↗

arXiv2021

Interaction Theory of Hazard-Target System

Major accidents (e.g., the Space Shuttle Challenger disaster in the USA, the Bhopal Disaster in India, Fukushima nuclear accident in Japan, Tianjin Port fire and explosion accident in China) have occurred all over the world. Safety scientists are always trying to understand why these accidents happened and how to prevent these accidents. Accident models and theories form the basis for many safety research fields and practices such as investigation of accidents, design of a safer system and decision making on safety related field. There is no universally accepted model with useful elements relating to understanding accident causation, although many accident causation models exist. Based on STAMP and RMF, we proposed a new theory named the Interaction Theory of Hazard-Target System (ITHTS) that incorporate human, organisational and technological characteristics in the same framework. Accident analysis methods provide the necessary information to analysis the accident in a specific setting. In order to solve the issues that current accident analysis methods still face, we proposed a new systemic accident analysis method based on ITHTS and STPA. We choose Tianjin Port fire and explosion accident in China as a case study to demonstrate the viability of the Interaction Theory of Hazard-target System and the applicability of the new accident analysis method. It is concluded that ITHTS can explain the phenomena in safety practice and the new accident analysis method can be application in the explanation and analysis of major accident.

eess.SY↗

arXiv2021

Cooperator driven oscillation in a time-delayed feedback-evolving game

Considering feedback of collective actions of cooperation on common resources has vital importance to reach sustainability. But such efforts may have not immediate consequence on the state of environment and it is unclear how they influence the strategic and environmental dynamics with feedbacks. To address this issue, we construct a feedback-evolving game model in which we consider the growth capacity of resources and the punishment efficiency on defectors who do not provide returns to the environment. Importantly, we further assume a delay in adopting the contribution of cooperative individuals to environmental change in our model. We find that when this contribution amount from cooperators' endowment is fixed, the time delay has no particular consequence on the coevolutionary dynamics. However, when the return is proportional to their endowment, then the time delay can induce periodic oscillatory dynamics of cooperation level and environment. Our work reveals the potential effects of time delay of cooperative actions on the coevolutionary dynamics in strategic interactions with environmental feedback.

physics.soc-ph↗

arXiv2021

Integrated Age Estimation Mechanism

Machine-learning-based age estimation has received lots of attention. Traditional age estimation mechanism focuses estimation age error, but ignores that there is a deviation between the estimated age and real age due to disease. Pathological age estimation mechanism the author proposed before introduces age deviation to solve the above problem and improves classification capability of the estimated age significantly. However,it does not consider the age estimation error of the normal control (NC) group and results in a larger error between the estimated age and real age of NC group. Therefore, an integrated age estimation mechanism based on Decision-Level fusion of error and deviation orientation model is proposed to solve the problem.Firstly, the traditional age estimation and pathological age estimation mechanisms are weighted together.Secondly, their optimal weights are obtained by minimizing mean absolute error (MAE) between the estimated age and real age of normal people. In the experimental section, several representative age-related datasets are used for verification of the proposed method. The results show that the proposed age estimation mechanism achieves a good tradeoff effect of age estimation. It not only improves the classification ability of the estimated age, but also reduces the age estimation error of the NC group. In general, the proposed age estimation mechanism is effective. Additionally, the mechanism is a framework mechanism that can be used to construct different specific age estimation algorithms, contributing to relevant research.

cs.CV↗

arXiv2017

Commissioning of te China-ADS injector-I testing facility

The 10 MeV accelerator-driven subcritical system (ADS) Injector-I test stand at Institute of High Energy Physics (IHEP) is a testing facility dedicated to demonstrate one of the two injector design schemes [Injector Scheme-I, which works at 325 MHz], for the ADS project in China. The Injector adopted a four vane copper structure RFQ with output energy of 3.2 MeV and a superconducting (SC) section accommodating fourteen \b{eta}g=0.12 single spoke cavities, fourteen SC solenoids and fourteen cold BPMs. The ion source was installed since April of 2014, periods of commissioning are regularly scheduled between installation phases of the rest of the injector. Continuous wave (CW) beam was shooting through the injector and 10 MeV CW proton beam with average beam current around 2 mA was obtained recently. This contribution describe the results achieved so far and the difficulties encountered in CW commissioning.

physics.acc-ph↗

arXiv2014

Transverse profile expansion and homogenization at target for the injector Scheme-I test stand of China-ADS

For the injector Scheme-I test stand of the China-ADS, a beam with the maximum power of 100 kW will be produced and transported to the beam dump. At the beam dump, the beam power will be converted to thermal load and brought away by the cooling water. Two measures are taken to deal with the huge power density at the target. One is to enlarge the contact area between the beam and the target, and this is to be accomplished by expanding the beam profile at the target and using two copper plates each having a 20o inclination angle relative to the beam direction. The other is to produce more homogenous beam profile at the target to minimize the maximum power density. Here the beam dump line is designed to meet the requirement of beam expansion and homogenization, and the step-like field magnets are employed for the beam spot homogenization. The simulations results including space charge effects and errors show that the beam line can meet the requirements very well at the three different energies (3.2 MeV, 5 MeV and 10 MeV). In the meantime, the alternative beam design using standard multipole magnets is also presented.

physics.acc-ph↗

arXiv2013

Physics design for the C-ADS main linac basing on two different injector design schemes

The China ADS (C-ADS) project is proposed to build a 1000 MW Accelerator Driven sub-critical System around 2032. The accelerator will work in CW mode with 10 mA in beam current and 1.5 GeV in final beam energy. The linac is composed of two major sections: the injector section and the main linac section. There are two different schemes for the injector section. The Injector-I scheme is based on a 325-MHz RFQ and superconducting spoke cavities of same RF frequency and the Injector-II scheme is based on a 162.5-MHz RFQ and superconducting HWR cavities of same frequency. The main linac design will be different for different injector choice. The two different designs for the main linac have been studied according to the beam characteristics from the different injector schemes.

physics.acc-ph↗