变量施肥决策的多目标优化模型与算法

变量决策模型和优化算法是精准农业变量作业处方生成的核心环节.文中建立了一个综合考虑作物产量、质量、能源消耗、环境影响等多个指标的变量施肥多目标优化模型,提出了一种求解此类问题的高效禁忌搜索算法,从产量最大化的初始施肥方案出发,基于最近可行解的概念进行邻域搜索,并按照质量优先的策略不断寻找和更新解集,最后得到一组非支配意义下的优化施肥方案,以提高精准农业变量施肥的决策支持能力和水平.通过对江西宜春地区油茶树变量施肥问题的案例研究,验证了模型和算法的有效性和实用性.     

Study on the electronic structure of nickel hydroxide by quantum chemical DV-Xα calculation

The electronic structures of atom clusters NiTO12H12^2＋ and NiTO12H9^- of β-Ni（OH）2 were calculated by quantum chemical DV-Xα method. By analyzing the state densities, orbital populations, net charges and electric charge density differences of the selected clusters, it was indicated that β-Ni（OH）2was not typical ionic crystal, and the bonds between Ni and O atoms had obvious covalent characteristics. The bonds between H atom and other atoms in the crystal structure were weaker, which ensured that H atoms can easily deintercalate and intercalate into β-Ni（OH）2. The structure of β-Ni（OH）2 was not changed by moderate de-intercalation of H atoms. However, with the excessive de-intercalation of H atoms, the structure of β-Ni（OH）2 changed and the electrochemical active properties were reduced.     

Electron emission from La-doped Pb（Zr,Sn,Ti）O3 antiferroelectrics by pulse electric field and the relevant physical mechanism

We investigate the characteristics of emission current waves of antiferroelectric cathode material lanthanum-doped lead zirconate stannate titanate （PLZST） triggered by pulse field, and analyze the relationship of the emission current waveforms with the extraction voltage. The close correlation between the triggering pulse polarity and emission current waveform observed evidences the relevant physical process of electron emission. We speculate that the primary emission may result from local phase transition and field emission in the vicinity of triple junctions, and the plasma formation may enhance the electron emission.     

p-moment stability of stochastic impulsive differential equations and its application in impulsive control

The exponential p-moment stability of stochastic impulsive differential equations is addressed.A new theorem to ensure the p-moment stability is established for the trivial solution of the stochastic impulsive differential system.As an application of the theorem proposed,the problem of controlling chaos of Lorenz system which is excited by parameter white-noise excitation is considered using impulsive control method.Finally,numerical simulation results are given to verify the feasibility of our approach.     

单分子体系发射光子统计

基于最近发展的单分子体系光子发射产生函数(generating function)方法, 具体讨论了单分子体系发射光子统计的有关问题. 从统计的意义上讲, 所引进的产生函数可以认为是单分子体系发射光子系综的广义配分函数, 并对相关问题作了简要的讨论.     

非自治扩散系统的强单调性

单调系统理论在微分方程中具有重要的理论意义和应用价值。针对由反应扩散微分方程所描述的非自治非线性系统，该文主要研究了该非自治非线性系统的强单调性质。在系统的单调性和解存在惟一的条件下，该文利用反应扩散方程组的比较原理和矩阵的不可约性质，得到了该系统的解所具有的强单调性的充分条件，推广了以前相应的结果。     

Molecular dynamics simulation of the deposition process of hydrogenated diamond-like carbon （DLC） films

The deposition process of hydrogenated diamond-like carbon （DLC） film greatly affects its frictional properties. In this study, CH3 radicals are selected as source species to deposit hydrogenated DLC films for molecular dynamics simulation. The growth and structural properties of hydrogenated DLC films are investigated and elucidated in detail. By comparison and statistical analysis, the authors find that the ratio of carbon to hydrogen in the films generally shows a monotonously increasing trend with the increase of impact energy. Carbon atoms are more reactive during deposition and more liable to bond with substrate atoms than hydrogen atoms. In addition, there exists a peak value of the number of hydrogen atoms deposited in hydrogenated DLC films. The trends of the variation are opposite on the two sides of this peak point, and it becomes stable when impact energy is greater than 80 eV. The average relative density also indicates a rising trend along with the increment of impact energy, while it does not reach the saturation value until impact energy comes to 50 eV. The hydrogen content in source species is a key factor to determine the hydrogen content in hydrogenated DLC films. When the hydrogen content in source species is high, the hydrogen content in hydrogenated DLC films is accordingly high.     

Influence of pulse polarity on electron emission property of antiferroelectric ceramic

The electron emission property of a novel antiferroelectric cathode material lanthanum-doped lead zirconate stannate titanate （PLZST） on the application of positive or negative triggering voltage pulses has been investigated. All experiments were performed in a vacuum of 10-5 Torr and at room temperature. It was discovered that there were two electron emission pulses when low positive triggering voltage was applied to the rear electrode, and three electron emission pulses when high positive triggering voltage was applied. However there were always two electron emission pulses when negative triggering pulses were applied. This phenomenon is proposed to be a result of both field electron emission at triple junctions and electron emission caused by polarization reversal. The experimental observations indicate that domain movement in the vicinity close to the triple junction under applica- tion of the triggering voltage pulse may be a primary origin of electron emission from PLZST.     

基于TM影像的水体信息提取算法研究

以郑洛地区为研究区域,利用LandsatTM影像进行波谱再分析,对谱间关系法进行改进,设计了更适合于郑洛地区水体信息提取的算法。通过综合比较和分析单波段阈值法、谱间关系法、归一化水体指数法和IHS(intensity hue saturation)变换法,借助数学形态学、中值滤波等进行优化处理,进而提出了改进的谱间关系法。实验证明该改进算法具有有效性,提取效果良好,能够提取到较细小的河流等水体信息。河流细节丰盈,山体阴影较少,总体精度较高,与实际情况一致性较好。     

Shiga toxin-producing Escherichia coli O104:H4: An emerging important pathogen in food safety

In 2011, Shiga toxin-producing Escherichia coli O104:H4 resulted in a large outbreak of bloody diarrhea and hemolytic uremic syndrome (HUS) in Germany and 15 other countries in Europe and North America. This event raised a serious public health crisis and caused more than two billion US dollars in economic losses. In this review, we describe the classification of E. coli, the Germany outbreak, and the characteristics and epidemical source-tracing of the causative agent. We also discuss the genomics analysis of the outbreak organism and propose an open-source genomics analysis as a new strategy in combating the emerging infectious diseases.