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Changchun, China

Zhang Z.,Changchun University of Science and Technology | Zhang Z.,CAS Changchun Observatory | Wang Z.,Changchun University of Science and Technology | Wang Z.,University of Bedfordshire | And 4 more authors.
Journal of Laser Applications

Silicon surface structures with excellent antireflection property arouse wide interest. Chemical and physical methods such as femtosecond, nanosecond, and picosecond laser processing, wet-chemical etching, electrochemical etching, and reactive ion etching have been developed to fabricate them. However, the methods can only produce a quasi-ordered array of sharp conical microspikes on silicon surface. In this paper, we present a method to fabricate periodic silicon antireflection surface structures using direct four-beam laser interference lithography (LIL). With 1 atm ambient atmosphere of SF6 and the laser fluence of the four beams irradiated on the silicon surface at 0.64 J cm-2, the periodical conical spikes were generated. Changing the polarization directions of the opposite incident beam pairs in a four-beam LIL system could convert conical spikes structure into an array of holes. Antireflection in a wide spectral range was measured by a spectrophotometer from ultraviolet to near-infrared. The average reflectance of this periodic black silicon surface is less than 3.5%. © 2014 Laser Institute of America. Source

Ma S.,CAS Changchun Observatory | Wang Q.,Institute of Meteorological science of Jilin Province | Yu H.,Agrometeorological Observatory of Yushu County | Xu L.,Agrometeorological Observatory of Yushu County | Zhang T.,Agrometeorological Observatory of Yushu County
Journal of Natural Disasters

This paper studies the influence of spring drought on maize yield based on the combination tests of soil water stress test and field test of seeding trials. Results show that during the corn planting and emerging periods, the relationship between soil water content and corn yield follows a quadratic function. Spring water stress of soil on maize yield is very obvious. In field water capacity, soil humidity declied by 1 percentage points each, maize yield will be reduced by about 7% ; soil effective water reduction for every 10 mm,per unit area yield will drop about 14%. The article also identified maize drought index of soil moisture. The influence of soil moisture decrease on the corn yield was quantitatively studied. The indicator and mode of soil moisture influence on maise yield can be used for developing the assessment and prediction of maize spring drought, and can also be used to determine drought-resistant irrigation content. Source

Ma S.,CAS Changchun Observatory | Wang Q.,Institute of Meteorological science of Jilin Province | Lu H.,National Meteorological Center | Xu L.,Agrometeorological Observatory of Yushu County of Jilin Province | And 2 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica

Maize emergence speed and the emergence rate relate to soil moisture and air temperature, and they largely determine the corn growth and yield. In order to obtain the relationships between seedling emergence speed, seedling rate of spring maize (Zea mays) and soil moisture and air temperature respectively, the experiments of water stress and by-stage sowing for spring maize were conducted at an agro-meteorological experiment station in the central part of Northeastern China. In an artificial rain-proof cover, 4 water treatments (not drought, light drought, drought and severity drought) and 3 sowing treatments (early, middle and late) were set to create soil moisture variation and air temperature difference during the period from sowing to germination. And soil moisture, water amount for irrigation, rainfall, air temperature, the seedling stage and emergence rate were observed. The results showed that the relationships between soil moisture and emergence rate, period of emergence both were significantly quadratic function during the periods of sowing and emerging. Below field capacity, the greater soil moisture was, the faster the corn came out and the higher the emergence rate was. Soildrought delayed the period of emergence and decreased emergence rate. Low temperature slowed down the emergence, but had little effect on emergence rate. The equation of relationship between days from sowing to emerging (D), soil moisture (S) at a depth of 0 to 20 cm and average air temperature (T) was D = 63. 450-1. 194S -1. 442T. The equation of relationship between emergence rate (P), S and T was P =5. 107 S +1. 857 T-56. 5. Combinational influence indexes of average soil moisture, effective soil water (H) and air temperature on maize emergence speed were that corn emerged quickly when 25% >S>21%, 70 mm>H>45 mm and T>18°C; it would emerge normally when 21% >S>18%, 45 mm>H> 35 mm and 18°C >T>16. 5°C; and it would emerge slowly when 18% >S>16%, 35 mm>H> 25 mm and 16. 5 °C >T>15. 5 °C; and the emergence was postponed remarkably when S<16%, H<25 mm and T<15. 5 °C. Germination rate depended mainly on soil moisture in this study. The highest germination rate (more than 95%) occurred when S >85% and H > 50mm; the higher one (about 90%) when relative humidity was about 80% and 50 mm>H>40 mm; and the lower one when relative humidity was less than 70% and 50 mm>H>40 mm; and the one was less than 65% when relative humidity was less than 60% and H<30 mm, and the serious drought happened. Source

Xu Y.,CAS Changchun Observatory | Liu G.-Z.,Jilin University | Wang H.-Y.,Jilin University | Ding W.-B.,Bohai University | Zhao E.-G.,CAS Institute of Theoretical Physics
Chinese Physics Letters

Within the framework of the relativistic mean field theory, we investigate the 1S 0 superfluidity (SF) of Λ hyperons in neutron star (NS) matter including σ* and mesons. The energy gap of Λ hyperons is calculated with the Nijmegen one-boson-exchange potentials for a ΛΛ pair. The parameter set we use is in line with the recent experimental data ΔB ΛΛ∼1.01±0.20 +0.18 -0.11MeV. It is found that with σ* and mesons the pairing energy gap Δ F of Λ hyperons and the corresponding SF critical temperature T CΛ; are suppressed. In addition the NS mass range of Λ hyperon SF is enlarged obviously. © 2012 Chinese Physical Society and IOP Publishing Ltd. Source

Li Z.-W.,CAS Changchun Observatory | Zhang T.,CAS Changchun Institute of Optics and Fine Mechanics and Physics | Zhang N.,CAS Changchun Observatory | Sun M.-G.,CAS Changchun Observatory
Guangxue Jingmi Gongcheng/Optics and Precision Engineering

A high precision orientation method for faint space objects was presented to improve the positioning accuracy of this kind of space objects in photoelectric reconnaissance. Several relevant algorithms were investigated, such as star centroid computing, star pattern matching, correction models for static pointing of optoelectronic telescope, and the astronomical orientation of space objects. The star centroid computing method and star identification using triangle algorithm were firstly analyzed. Then, the Tycho-2 catalog and basic parameter pointing model were used to correct the static pointing error of the optoelectronic telescope. Finally, by considering lower orientation precision of faint space objects, the high precision orientation algorithm of faint space objects was presented based on the improved traditional astronomical orientation method to realize the high precision orientation of space objects. Experimental results indicate that the measuring precision of the high precision orientation method for faint space objects is superior to 4″, which satisfies the system requirements of faint space object surveillance for the precision and stabilization. ©, 2015, Chinese Academy of Sciences. All right reserved. Source

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