A Statistical Study on Photospheric Magnetic Nonpotentiality of Active Regions and Its Relationship with Flares during Solar Cycles 22-23

A statistical study is carried out on the photospheric magnetic nonpotentiality in solar active regions and its relationship with associated flares. We select 2173 photospheric vector magnetograms from 1106 active regions observed by the Solar Magnetic Field Telescope at Huairou Solar Observing Station, National Astronomical Observatories of China, in the period of 1988-2008, which covers most of the 22nd and 23rd solar cycles. We have computed the mean planar magnetic shear angle (\bar{\Delta\phi}), mean shear angle of the vector magnetic field (\bar{\Delta\psi}), mean absolute vertical current density (\bar{|J_{z}|}), mean absolute current helicity density (\bar{|h_{c}|}), absolute twist parameter (|\alpha_{av}|), mean free magnetic energy density (\bar{\rho_{free}}), effective distance of the longitudinal magnetic field (d_{E}), and modified effective distance (d_{Em}) of each photospheric vector magnetogram. Parameters \bar{|h_{c}|}, \bar{\rho_{free}}, and d_{Em} show higher correlation with the evolution of the solar cycle. The Pearson linear correlation coefficients between these three parameters and the yearly mean sunspot number are all larger than 0.59. Parameters \bar{\Delta\phi}, \bar{\Delta\psi}, \bar{|J_{z}|}, |\alpha_{av}|, and d_{E} show only weak correlations with the solar cycle, though the nonpotentiality and the complexity of active regions are greater in the activity maximum periods than in the minimum periods. All of the eight parameters show positive correlations with the flare productivity of active regions, and the combination of different nonpotentiality parameters may be effective in predicting the flaring probability of active regions.Comment: 20 pages, 5 figures, 4 tables, accepted for publication in Solar Physic

Numerical investigation on the effect of reactivity gradient in an RCCI engine fueled with gasoline and diesel

10.1016/j.enconman.2014.12.071Energy Conversion and Management92342-35

Study on impact of grid connection of distributed photovoltaic system on distribution network peak-valley difference considering photovoltaic volatility

In this paper, firstly an IEEE 13 node feeder system simulation model is established in Matlab/simulink. Then, taking into consideration the typical photovoltaic output fluctuation and daily load curve of the distribution network, and with simulation method, the study obtains the value of the system peak-valley difference considering the superposition of fluctuation of load and photovoltaic output. Furthermore, the paper studies the relationship between the peak-valley difference and the photovoltaic access modes, as well as capacity and operating condition, thus drawing the law of influence of connected photovoltaic system on peak-valley difference. The conclusions of the study can provide an operation reference for the determination of photovoltaic-grid- connection scheme and the peak regulation and planning of distribution network with connected photovoltaic system

Stochastic cooling experiments for CSRe at IMP

A novel type of perforated travelling wave pick-up/kicker structure was developed for CSRe stochastic cooling which was originally proposed by F.Caspers at CERN. The simulated and measured results of shunt impedance of the slotted travelling wave pickup electrode are in reasonable agreement. In December 2015 stochastic cooling of heavy ions was successfully applied for the first time at the CSRe storage ring of IMP in Lanzhou, China. During four days of commissioning, transverse and longitudinal cooling could be observed. Both the time-of-flight and the notch filter methods were used for longitudinal cooling. The measured cooling rates are presented