江河源区人工草地群落特征、多样性及其稳定性分析

对江河源区人工草地群落特征、多样性及其稳定性的研究结果表明,不同处理草地植物群落的物种丰富度、多样性、均匀度指数因时间和空间的变化而有明显的差异,群落演替从5龄到6龄,各群落丰富度和多样性指数增加,生物生产量降低,群落相似性系数增大.5龄老芒麦+早熟禾混播人工草地(LP5)群落的地上生物量最高(379.6 g/m2),老芒麦单播(ES5)居中(323.4 g/m2),对照组(CKF5和CK5)最低(124.3和118.6 g/m2).6龄植物群落地上生物量依次为原生植被+封育(VP6,310.1 g/m2)>老芒麦+早熟禾混播(LP6,216.3 g/m2)>老芒麦单播(ES6,190.8 g/m2)>对照(CK6,88.7 g/m2).群落间相似性系数的变化说明,单播(ES)与混播(LP)人工草地群落有趋同演化的趋势.人工草地群落随着结构的复杂化,与对照群落间的相似性提高,说明群落处于退化演替阶段,物种丰富度和多样性增大,群落稳定性提高.

聚类引导搜索的移动机器人路径规划方法

本文提出一种聚类引导搜索（cluster guide searching，CGS）的路径规划方法。采用基于最大最小距离的K均值聚类方法对样本进行离线聚类学习，学习结果以相似环境相似决策的知识形式进行存储。路径规划过程中，机器人在线整理环境信息，获得输入空间样本，通过与知识库匹配，检索到最近的类别，然后在该类别内部采用速度优先策略和方向优先策略交替的方式搜索输出空间。若知识不完备导致检索失败，可重启线性规划算法（linear programming，LP）进行在线路径规划，并更新聚类知识库。仿真结果表明该方法是一种有效的路径规划学习方法。

加速度空间中基于线性规划的移动机器人路径规划方法

针对动态不确定环境下移动机器人的路径规划问题,提出了加速度空间中一种基于线性规划(Linear programming,LP)的方法.在机器人的加速度空间中利用相对信息,把机器人路径规划这一非线性问题,描述成满足一组线性约束同时使目标函数极小的线性规划问题,嵌入基于线性规划方法的规划器,得到一条满足性能要求的最优路径.仿真试验验证了算法的实用性及有效性,与势场引导进化计算的方法(Artificial potential guided evolution algorithm,APEA)相比更优化,更实时.

基于遗传退火算法的装配线设计多目标优化方法

针对混装配线设计这一有约束的多目标优化问题,建立了数学模型。将基于Pareto的解的分级方法与Lp-范数形式的非线性机制相组合,构建了基于遗传退火算法多目标优化方法。重点阐述了个体编码、染色体检修、多目标处理机制等关键技术。设计了算法流程图,并开发了优化程序。该方法克服了加权和方法的不足,用模拟退火改善了遗传算法全局寻优性能。计算实例表明,随着迭代次数的增加,每代的非受控点逐渐收敛于Pareto最优边界,是一种混装线设计多目标优化的新方法。

f-x-y域去除随机噪音方法研究

The seismic survey is the most effective prospecting geophysical method during exploration and development of oil/gas. The structure and the lithology of the geological body become increasingly complex now. So it must assure that the seismic section own upper resolution if we need accurately describe the targets. High signal/noise ratio is the precondition of high-resolution. For the sake of improving signal/noise ratio, we put forward four methods for eliminating random noise on the basis of detailed analysis of the technique for noise elimination using prediction filtering in f-x-y domain. The four methods are put forward for settling different problems, which are in the technique for noise elimination using prediction filtering in f-x-y domain. For weak noise and large filters, the response of the noise to the filter is little. For strong noise and short filters, the response of the noise to the filter is important. For the response of the noise, the predicting operators are inaccurate. The inaccurate operators result in incorrect results. So we put forward the method using prediction filtering by inversion in f-x-y domain. The method makes the assumption that the seismic signal comprises predictable proportion and unpredictable proportion. The transcendental information about predicting operator is introduced in the function. The method eliminates the response of the noise to filtering operator, and assures that the filtering operators are accurate. The filtering results are effectively improved by the method. When the dip of the stratum is very complex, we generally divide the data into rectangular patches in order to obtain the predicting operators using prediction filtering in f-x-y domain. These patches usually need to have significant overlap in order to get a good result. The overlap causes that the data is repeatedly used. It effectively increases the size of the data. The computational cost increases with the size of the data. The computational efficiency is depressed. The predicting operators, which are obtained by general prediction filtering in f-x-y domain, can not describe the change of the dip when the dip of the stratum is very complex. It causes that the filtering results are aliased. And each patch is an independent problem. In order to settle these problems, we put forward the method for eliminating noise using space varying prediction filtering in f-x-y domain. The predicting operators accordingly change with space varying in this method. Therefore it eliminates the false event in the result. The transcendental information about predicting operator is introduced into the function. To obtain the predicting operators of each patch is no longer independent problem, but related problem. Thus it avoids that the data is repeatedly used, and improves computational efficiency. The random noise that is eliminated by prediction filtering in f-x-y domain is Gaussian noise. The general method can't effectively eliminate non-Gaussian noise. The prediction filtering method using lp norm (especially p=l) can effectively eliminate non-Gaussian noise in f-x-y domain. The method is described in this paper. Considering the dip of stratum can be accurately obtained, we put forward the method for eliminating noise using prediction filtering under the restriction of the dip in f-x-y domain. The method can effectively increase computational efficiency and improve the result. Through calculating in the theoretic model and applying it to the field data, it is proved that the four methods in this paper can effectively solve these different problems in the general method. Their practicability is very better. And the effect is very obvious.

伽马射线谱仪探测月球表面元素的分布——以“嫦娥一号”伽马射线谱仪为例

Apollo和Lunar Prospector(LP) 携带的伽马射线谱仪探测了月球表面的氧（O）、硅（Si）、铝（Al）、铁（Fe）、钛（Ti）、钙（Ca）、钾（K）、镁（Mg）、钍（Th）和铀（U）等10种元素的全球分布，对于了解月球的形成与演化有重要的意义。在我国首颗月球探测卫星“嫦娥一号”上搭载了伽马射线谱仪将进一步探测月球表面14种元素的分布特征。本论文的选题紧密结合“嫦娥一号”伽马射线谱仪数据处理和科学反演工作的工程需求，系统研究了伽马射线谱仪探测数据的处理流程和反演方法，并利用LP的数据开展了月球元素、岩石类型及其分布特征的反演工作，为嫦娥一号卫星伽马射线谱仪的数据处理和反演奠定了技术基础。论文主要包括如下几个方面的内容： （1）概述了伽马射线谱仪探测月球表面元素的发展历程，特别是阐述了伽马射线产生的机理和伽马射线谱仪元素探测的原理； （2）讨论了伽马射线谱仪数据反演及其模型，以及在“嫦娥一号”伽马射线谱仪数据反演中的应用； （3）阐述了“嫦娥一号”伽马射线谱仪性能指标，数据处理流程，地面验证实验（模拟月壤的研制及其试验）和初步的探测成果； （4）以LP伽马射线谱仪探测数据为例，讨论了伽马射线谱仪探测数据科学反演工作，阐述了全球Th的分布特征以及月球化学不均一性的相关性；用LP探测数据首次划分出月球岩石类型的分布，探讨了月球演化对岩石类型分布特征的影响。

Experimental investigation of an unstable ring resonator with 90-deg beam rotation for a chemical oxygen iodine laser

We report the experimental results of an unstable ring resonator with 90-deg beam rotation for a kilowatt class chemical oxygen iodine laser (COIL). The distributions of near-field phase and far-field intensity were measured. A beam quality of 1.6 was achieved when the COIL average output power was approximately 5 kW. (C) 1999 Optical Society of America.

海洛因成瘾脑灰质密度和结构网络研究

Behavioral and functional imaging studies consistently show that heroin abuse leads to various cognitive impairments, while brain structural changes associated with heroin use remain poorly understood. In the current study, we used voxel-based morphology (VBM), a method sensitive to structural changes of the brain, to investigate the gray concentration in MRI structure images of heroin addicts. Results show that the concentration of the temporal cortex and frontal cortex of heroin users significantly decreased as compared to age/education matched normal controls. Further analysis revealed that this brain structure change was detectable only in the users who had used heroin more than 5 year, but not in the remaining users. These results converge to the abnormality of the brain structure in heroin users and this abnormality is clearly associated with duration of drug use. We then analyzed the large-scale brain structure network in the heroin addicts. As compared to the normal controls, there was significant difference in interregional correlation between the temporal cortex, hippocampus, thalamus, and frontal cortex. Importantly, two major indices of the small-world properties, Clustering coefficient(Cp) and shortest path length (Lp), which are thought to reflect the local specialty and global integrity, were marginal-significantly larger than the normal controls, especially for Lp. These results suggest that chronic use of heroin results in the reorganization of the brain system. Taken together, this thesis has provided compelling evidence for brain structure impairments in chronic heroin users and further characterized the large-scale brain structure network in the same population.

Catalytic oxidation of cyclohexane to cyclohexanol and cyclohexanone over Co3O4 nanocrystals with molecular oxygen

Co3O4 nanocrystals with average particle sizes of 30 and 50 run were synthesized using cobalt nitrate as precursor, and were characterized by X-ray diffraction (XRD), nitrogen adsorption, transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) spectroscopy. Catalytic oxidation of cyclohexane with molecular oxygen was studied over Co3O4 nanocrystals. These catalysts showed obviously higher activities as compared to Co3O4 prepared by the conventional methods, Co3O4/Al2O3, or homogeneous cobalt catalyst under comparable reaction conditions. The 89.1% selectivity to cyclohexanol and cyclohexanone at 7.6% conversion of cyclohexane was realized over 50 nm sized Co3O4 nanocrystals at 393 K for 6 h. (c) 2005 Elsevier B.V. All rights reserved.

Synthesis of FeCoMnAPO-5 molecular sieve and catalytic activity in cyclohexane oxidation by oxygen

A new FeCoMnAPO-5 with AFI structure was synthesized under hydrothermal conditions and characterized by XRD, FT-IR, X-ray fluorescence, nitrogen adsorption and SEM. The oxidation of cyclohexane with molecular oxygen was studied over the catalyst at 403 K. It show d higher activity compared to FeAPO-5, CoAPO-5 and MnAPO-5. The FeCoMnAPO-5 catalyst was recycled twice without loss of activity or selectivity.

A novel approach to Co/CNTs catalyst via chemical vapor deposition of organometallic compounds

A novel approach for attaching well-dispersed cobalt nanoparticles homogeneously onto carbon nanotubes via metal organic chemical vapor deposition technique is reported. The obtained Co/CNTs catalysts feature a narrow size distribution of Co particles centering around 7.5 nm, and show high activity and regioselectivity for hydroformylation of 1-octene.

Liquid phase oxidation of toluene to benzaldehyde with molecular oxygen over copper-based heterogeneous catalysts

We conducted the liquid phase oxidation of toluene with molecular oxygen over heterogeneous catalysts of copper-based binary metal oxides. Among the copper-based binary metal oxides, iron-copper binary oxide (Fe/Cu = 0.3 atomic ratio) was found to be the best catalyst. In the presence of pyridine, overoxidation of benzaldehyde to benzoic acid was partially prevented. As a result, highly selective formation of benzaldehyde (86% selectivity) was observed after 2 h of reaction (7% conversion of toluene) at 463 K and 1.0 MPa of oxygen atmosphere in the presence of pyridine. These catalytic performances were similar or better than those in the gas phase oxidation of toluene at reaction temperatures higher than 473 K and under 0.5-2.5 MPa. It was suggested from competitive adsorption measurements that pyridine could reduce the adsorption of benzaldehyde. At a long reaction time of 4 It, the conversion increased to 25% and benzoic acid became the predominant reaction product (72% selectivity) in the absence of pyridine. The yield of benzoic acid was higher than that in the Snia-Viscosa process, which requires corrosive halogen ions and acidic solvents in the homogeneous reaction media. The catalyst was easily recycled by simple filtration and reusable after washing and drying.

Maximal L p -regularity for the Laplacian on Lipschitz domains

I.Wood: Maximal Lp-regularity for the Laplacian on Lipschitz domains, Math. Z., 255, 4 (2007), 855-875.

Propagation of the degree of polarisation in a few-mode optical fibre: Experimental results

R. Zwiggelaar and M.G.F. Wilson, 'Propagation of the degree of polarisation in a few-mode optical fibre: Experimental results', International Journal of Optoelectronics 10 (4), 295-297 (1996)