Explaining the DAMPE data with scalar dark matter and gauged $$U(1)_{L_e-L_\mu }$$ U ( 1 ) L e - L μ interaction

Cao, Junjie,Feng, Lei,Guo, Xiaofei,Shang, Liangliang,Wang, Fei,Wu, Peiwen,Zu, Lei Springer-Verlag 2018 European Physical Journal C Vol.78 No.3

Scalar dark matter interpretation of the DAMPE data with U(1) gauge interactions

Cao, Junjie,Feng, Lei,Guo, Xiaofei,Shang, Liangliang,Wang, Fei,Wu, Peiwen American Physical Society 2018 Physical review. D Vol.97 No.9

<P>Recently, the Dark Matter Particle Explorer (DAMPE) experiment released the new measurement of the total cosmic e(+) e(-) flux between 25 GeV and 4.6 TeV, which indicates a spectral softening at around 0.9 TeV and a tentative peak at around 1.4 TeV. We utilize a scalar dark matter (DM) model to explain the DAMPE peak by XX -> Z'Z' -> l (l) over barl'(l) over bar 'l with an additional anomaly-free gauged U (l) family symmetry, in which X, Z'and l((')) denote, respectively, the scalar DM, the new gauge boson, and l((')) = e, mu, tau, with m(x) similar to m(z)' similar to 2 x 1.5 (TeV). We first illustrate that the minimal framework Gsm X U(l)(Y') with the above mass choices can explain the DAMPE excess, which, however, be excluded by LHC constraints from the Z' searches. Then, we study a nonminimal framework G(SM) X U(l)(Y') x U(i)(Y') in which U(l)(Y') mixes with U(l)(Y'). We show that such a framework can interpret the DAMPE data and at the same time survive all other constraints including the DM relic abundance, DM direct detection, and collider bounds. We also investigate the predicted e(+) e(-) spectrum in this framework and find that the mass splitting Delta m = m(x) - m(z') should be less than about 17 GeV to produce the peaklike structure.</P>

Research of the Exciting Current Detection Method of MCR

Wang Jun,Wei Liangliang,Chen Feng,Nie Dexin,Lu Wenhua 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.5

Magnetic valve controllable reactor (MCR) is a kind of dynamic reactive power compensation device. The exciting current of MCR is one of the important indexes of operating condition of MCR. This paper firstly analyzed the principle of MCR, and deduced the relationship between the exciting current and the output current, verified by MATLAB/SIMULINK. And then an effective method to detect the exciting current was proposed by this paper. The method has the advantages of optical fiber isolation, high detection precision, strong anti-interference, etc. Finally, a 220v/1200var MCR was experimented in detail. The results demonstrate the accuracy of the theoretical analysis.

Dynamic response of a base-isolated CRLSS with baffle

Xuansheng Cheng,Bo Liu,Liangliang Cao,Dongpo Yu,Huan Feng 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.3

Although a rubber isolation cushion can reduce the dynamic response of a structure itself, it has little influence on the height of a sloshing wave and even may induce magnification action. Vertical baffles are set into a base-isolated Concrete Rectangular Liquid Storage Structure (CRLSS), and baffles are opened as holes to increase the energy dissipation of the damping. Problems of liquid nonlinear motion caused by baffles are described using the Navier-Stokes equation, and the space model of CRLSS is established considering the Fluid-Solid Interaction (FSI) based on the Finite Element Method (FEM). The dynamic response of an isolated CRLSS with various baffles under an earthquake is analyzed, and the results are compared. The results show that when the baffle number is certain, the greater the number of holes in baffles, the worse the damping effects; when a single baffle with holes is set in juxtaposition and double baffles with holes are formed, although some of the dynamic response will slightly increase, the wallboard strain and the height of the sloshing wave evidently decrease. A configuration with fewer holes in the baffles and a greater number of baffles is more helpful to prevent the occurrence of two failure modes: wallboard leakage and excessive sloshing height.

Dynamic response of a base-isolated CRLSS with baffle

Cheng, Xuansheng,Liu, Bo,Cao, Liangliang,Yu, Dongpo,Feng, Huan Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.3

Although a rubber isolation cushion can reduce the dynamic response of a structure itself, it has little influence on the height of a sloshing wave and even may induce magnification action. Vertical baffles are set into a base-isolated Concrete Rectangular Liquid Storage Structure (CRLSS), and baffles are opened as holes to increase the energy dissipation of the damping. Problems of liquid nonlinear motion caused by baffles are described using the Navier-Stokes equation, and the space model of CRLSS is established considering the Fluid-Solid Interaction (FSI) based on the Finite Element Method (FEM). The dynamic response of an isolated CRLSS with various baffles under an earthquake is analyzed, and the results are compared. The results show that when the baffle number is certain, the greater the number of holes in baffles, the worse the damping effects; when a single baffle with holes is set in juxtaposition and double baffles with holes are formed, although some of the dynamic response will slightly increase, the wallboard strain and the height of the sloshing wave evidently decrease. A configuration with fewer holes in the baffles and a greater number of baffles is more helpful to prevent the occurrence of two failure modes: wallboard leakage and excessive sloshing height.

Beryllium-7 and Lead-210 are Associated with an Increase in the Arctic Oscillation: Evidence from Atmospheric Aerosols in a Remote Tropical Region in East Asia

Xiaoxia Chen,Wuhui Lin,Xianwen He,Liangliang Feng,Kuo-Ying Wang 한국기상학회 2022 Asia-Pacific Journal of Atmospheric Sciences Vol.58 No.1

The Arctic Oscillation (AO) accounts for a large fraction of recent decadal climate trends in Northern Hemisphere (NH) high latitudes. In East Asia, an elevated AO index (AOI) was associated with warmer temperatures in middle- to high-latitude regions, colder temperatures over low-latitude regions, and elevated ozone intrusion from the stratosphere. Elevated beryllium-7 (7Be) is produced in the stratosphere. Few studies have discussed the relationship between 7Be and the AO. Here, we identify the AO signature in 7Be and lead (Pb)-210 observed at a tropical ambient monitoring site in Nanning (22.8°N, 108.5°E) during the December 2014–December 2017 period. Our results show that the 7Be and 210Pb concentrations are positively and significantly correlated with the AOI (P < 0.01). These results show that elevated 7Be and 210Pb are associated with an increase in the AOI, reflecting air masses originating from NH high latitudes and vertically from the high-latitude upper troposphere and lower stratosphere regions to tropical latitudes in East Asia. These results have been verified with ozonesonde data without seasonality and with two meteorological data sets. Our results are also confirmed by observational data over the Pacific regions. We conclude that the AO exerts impacts over the tropical regions in East Asia, and 7Be can be used as a tracer to track the impacts of the AO.

Synthesis and electrochemical performance of Li1þxV3O8 as cathode material prepared by citric acid and tartaric acid assisted solegel processes

Miao Shui,Weidong Zheng,Jie Shu,Qingchun Wang,Shan Gao,Dan Xu,Liangliang Cheng,Lin Feng,Yuanlong Ren 한국물리학회 2013 Current Applied Physics Vol.13 No.3

Lithium-ion battery cathode material Li1þxV3O8 is synthesized by a citric acid/tartaric acid assisted sol egel method and sintered at 350 C, 450 C and 550 C for 3 h for the formation of Li1þxV3O8 phase. The synthesized samples were fully characterized by FTIR, TG/DTA, XRD, SEM, EIS and chargeedischarge tests. Li1þxV3O8 material synthesized by tartaric acid assisted route and sintered at 450 C for 3 h shows best electro-chemical performance. It shows a high initial capacity of 249 mAh g1 and still reserves a discharge capacity of 260 mAh g1 after 50 cycles. Moreover, in the case of tartaric assisted products, no capacity decadence is observed in 50 cycles. XRD together with TG/DTA measurements reveal that compared with citric acid assisted products, the adoption of tartaric acid as chelating agent effectively lowers the crystallization temperature of amorphous Li1þxV3O8. Therefore, precursors obtained by tartaric acid route calcinated at 450 C for 3 h exhibit lower crystallinity and smaller grain size, which contributes to the better electrochemical performance of the cathode electrodes. From EIS measurements, the bulk resistance is reduced, which favors the intercalation and de-intercalation of lithium ions while cycling.

Time-domain simulations of transient response in LiFePO4 cathode lithium ion batteries

Xiaoping Xu,Miao Shui,Weidong Zheng,Jie Shu,Lei Hui,Linxia Xu,Liangliang Cheng,Lin Feng,Yuanlong Ren 한국물리학회 2014 Current Applied Physics Vol.14 No.5

The time domain transients of batteries comprised of LiFePO4 cathode material exhibit large nonlinearity with the increasing discharging rates. Hence, the calculated overpotential transients match the experimental determined well only when the discharging current is low enough. The results of electrochemical impedance spectra at different OCV level indicate that the change of the parameters of equivalent circuit or even the circuit architecture are probably responsible for the large discrepancy between the predicted and the measured transient profiles. By taking the change of equivalent circuit model at high discharging current into consideration, we successfully simulate the time domain transients of polarization within the entire discharging current range. Also with the help of circuit analysis, the contribution of the ohmic resistance, charge transfer impedance and solid-state diffusion impedance to total polarization has been differentiated as a function of discharging time.