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Search Results: 1 - 10 of 29929 matches for " Jiao Yi "
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Evolutionary genetic optimization of the injector beam dynamics for the ERL test facility at IHEP
Jiao Yi
Physics , 2013, DOI: 10.1088/1674-1137/38/8/088102
Abstract: The energy recovery linac test facility (ERL-TF), a compact ERL-FEL (free electron laser) two-purpose machine, was proposed at the Institute of High Energy Physics, Beijing. As one important component of the ERL-TF, the photo-injector started with a photocathode direct-current gun was designed and preliminarily optimized. In this paper an evolutionary genetic method, non-dominated sorting genetic algorithm II, is applied to optimize the injector beam dynamics, especially in the high-charge operation mode. Study shows that using an incident laser with rms transverse size of 1~1.2 mm, the normalized emittance of the electron beam can be kept below 1 mm.mrad at the end of the injector. This work, together with the previous optimization for the low-charge operation mode by using the iterative scan method, provides guidance and confidence for future constructing and commissioning of the ERL-TF injector.
Improving the nonlinear performance of the HEPS baseline design with genetic algorithm
Yi Jiao
Physics , 2015,
Abstract: The baseline design for the High Energy Photon Source has been proposed, with an emittance of 60 pm.rad within a circumference of 1.3 kilometers. Nevertheless, the nonlinear performance of the design needs further improvements to enlarge both the dynamic aperture and the momentum acceptance. In this study, genetic optimization of the linear optics is performed, so as to find all the possible solutions with weaker sextupoles and hence weaker nonlinearities, while keeping the emittance at the same level as the baseline design. These obtained solutions enable us to explore the dependence of nonlinear dynamics on the working point. The result indicates that with the same layout, it is feasible to obtain much better nonlinear performance with a delicate tuning of the magnetic field strengths and a wise choice of the working point.
Pulsed sextupole injection for Beijing Advanced Photon Source with ultralow emittance
Yi Jiao,Gang Xu
Physics , 2013, DOI: 10.1088/1674-1137/37/11/117005
Abstract: In this paper we present the physical design of the pulsed sextupole injection system for Beijing Advanced Photon Source (BAPS) with an ultralow emittance. The BAPS ring lattice is designed in such a way that two options of pulsed sextupole injection are allowed, i.e., with septum and pulsed sextupole in different drift spaces or in the same drift space. We give the magnetic parameters of the injection system and the optimal condition of the optical functions for both options. In addition, we find that the pulsed sextupole induces position-dependent dispersive effect and causes non-ignorable effect on the injection efficiency in a storage ring with a relatively small acceptance, which should be well considered.
Towards the ultimate storage ring: the lattice design for Beijing Advanced Photon Source
Xu Gang,Jiao Yi
Physics , 2013, DOI: 10.1088/1674-1137/37/5/057003
Abstract: A storage ring-based light source, Beijing Advanced Photon Source (BAPS) is proposed to store 5-GeV low-emittance electron beam and to provide high-brilliance coherent radiation. In this paper, we report our efforts of pushing down the emittance of BAPS to approach the so-called ultimate storage ring, while fixing the circumference to about 1200 m. To help dealing with the challenge of beam dynamics associated with the intrinsic very strong nonlinearities in an ultralow-emittance ring, a combination of several progressive technologies is used in the linear optics design and nonlinear optimization, such as modified theoretical minimum emittance cell with small-aperture magnets, quasi-3rd-order achromat, theoretical analyzer based on Lie Algebra and Hamiltonian analysis, multi-objective genetic algorithm, and frequency map analysis. These technologies enable us to obtain satisfactory beam dynamics in one lattice design with natural emittance of 75 pm.
PEPX-type lattice design and optimization for the High Energy Photon Source
Yi Jiao,Gang Xu
Physics , 2014, DOI: 10.1088/1674-1137/39/6/067004
Abstract: A new generation of storage ring-based light source, called diffraction-limited storage ring (DLSR), with the emittance approaching the diffraction limit for multi-keV photons by using the multi-bend achromat lattice, has attracted worldwide and extensive studies of several laboratories, and been seriously considered as a goal of upgrading the existing facilities in the imminent future. Among various DLSR proposals, the PEPX design based on the third-order achromat concept and with the special design of a high-beta injection straight section demonstrated that, it is feasible to achieve sufficient ring acceptance for off-axis injection in a DLSR. For the High Energy Photon Source planned to be built in Beijing, PEPX-type lattice has been designed and continuously improved. In this paper, we report the evolution of the PEPX-type design, and discuss the main issues relevant to the linear optics design and nonlinear optimization.
The species and community structure of white wax insect natural enemy in different production area in the oviposition period
不同产地白蜡虫(Ericerus pela Chavannes)产卵期天敌的种类及其群落结构研究


生态学报 , 2001,
Abstract: The oviposition period of white wax insect is the key period of white wax production.The species and numbers of its natural enemy were investigated in the 10 main production areas in the oviposition period of white wax insect.The results showed that there were 15 natural enemy species of white wax insect in the 10 communities.The dominants were \%Microterys ericeri\% Ishii.\%M.sinicus\% Jiang,\%Tetrastichus kodaikanalensis\% Saraswat,\%Anthribus lajievorus\% Chao and \%Chilocorus rubidus\% Hope.The aggregation index was relatively low in the 10 communities,but the diversity index and evennes index were high.The highest coefficient of community similarity was 97.46%,and the lowest coefficient was 75.92%.The main factors interfering with community similarity were the production area,ecological environment and different numbers of the dominants in different community.The 10 communities were divided into three groups by a systematic clustering analysis and two\|dimensional ordination.The first group is in the production area of the female white wax insect,the number of its natural enemy were relatively few.The second is in the production area of white wax,where the natural enemy number was much more than the first group.The third is in production area of both female white wax insect and white wax,the dominant natural enemy number was between the 1st and 2nd groups.The natural enemy harm of white wax insect is an important factor to cause that the white wax can not produce female seed insect.in some production areas.
Studies on the natural enemy communities of white wax insects in the period of secreting white wax


生态学报 , 1999,
Abstract: 选择有代表性的10个白蜡主产地,研究了各地白蜡虫天敌群落的物种组成和群落结构,并进行了聚类分析和排序。结果表明,白蜡白泌蜡期天敌群落共有捕食和寄生性天敌18种,各群落的优势种和物种变化较小,群落性程度较高,相似性系数最高达95.12%,最低为73.86%。影响群落相似性的主要因子为产区,地理位置,捕食性瓢虫的种类和数量。
Characterizing PM2.5 Pollution of a Subtropical Metropolitan Area in China  [PDF]
Guojin Sun, Lin Yao, Li Jiao, Yao Shi, Qingyu Zhang, Mengna Tao, Guorong Shan, Yi He
Atmospheric and Climate Sciences (ACS) , 2013, DOI: 10.4236/acs.2013.31012

The chemical and physical characteristics of PM2.5, especially their temporal and geographical variations, have been explored in metropolitan Hangzhou area (China) by a field campaign from September 2010 to July 2011. Annual average concentrations of PM2.5 and PM10 during non-raining days were 106 - 131 μg.m-3 and 127 - 158 μg.m-3, respectively, at three stations in urban breathing zones, while corresponding concentrations of PM2.5 and PM10 at an urban background station (16 mabove ground level in a park) were 78 and 104 μg.m-3, respectively. For comparison, the annual average PM10 concentration at a suburban station (5 mAGL) was 93 μg.m-3. Detailed chemical analyses were also conducted for all samples collected during the campaign. We found that toxic metals (Cd, As, Pb, Zn, Mo, Cu, Hg) were highly enriched in the breathing zones due to anthropogenic activities, while soluble ions (\"\", \"\",\"\" ) and total carbon accounted for majority of PM2.5 mass. Unlike most areas in China where sulfate was several times of nitrate in fine PM, nitrate was as important as sulfate and highly correlated with ammonium during the campaign. Thus, a historical shift from sulfate-dominant fine PM to nitrate-dominant fine PM was documented.

Power System Reactive Power Optimization Based on Fuzzy Formulation and Interior Point Filter Algorithm  [PDF]
Zheng Fan, Wei Wang, Tian-jiao Pu, Guang-yi Liu, Zhi Cai, Ning Yang
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B134

Considering the soft constraint characteristics of voltage constraints, the Interior-Point Filter Algorithm is applied to solve the formulation of fuzzy model for the power system reactive power optimization with a large number of equality and inequality constraints. Based on the primal-dual interior-point algorithm, the algorithm maintains an updating “filter” at each iteration in order to decide whether to admit correction of iteration point which can avoid effectively oscillation due to the conflict between the decrease of objective function and the satisfaction of constraints and ensure the global convergence. Moreover, the “filter” improves computational efficiency because it filters the unnecessary iteration points. The calculation results of a practical power system indicate that the algorithm can effectively deal with the large number of inequality constraints of the fuzzy model of reactive power optimization and satisfy the requirement of online calculation which realizes to decrease the network loss and maintain specified margins of voltage.

Realization of locally-round beam in an ultimate storage ring using solenoids
Xu Gang,Jiao Yi,Tian Saike
Physics , 2013, DOI: 10.1088/1674-1137/37/6/067002
Abstract: Ultimate storage rings (USRs), with electron emittance smaller than 100 pm.rad and on the scale of the diffraction limit for hard X-rays in both transverse planes, have the potential to deliver photons with much higher brightness and higher transverse coherence than that projected for the rings currently operational or under construction. Worldwide efforts have been made to design and to build light sources based on USRs. How to obtain a round beam, i.e. beam with equivalent transverse emittances, is an important topic in USR studies. In this paper, we show that a locally-round beam can be achieved by using a pair of solenoid and anti-solenoid with a circularly polarized undulator located in between. Theoretical analysis and application of this novel method, particularly to one of the Beijing Advanced Photon Source storage ring design having natural emittance of 75 pm.rad, are presented.
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