The processing and properties of (Zr,Hf)B2–SiC nanostructured composites

(Zr, Hf)B₂–SiC nanostructured composites were fabricated by high energy ball milling and reactive spark plasma sintering (RSPS) of HfB₂, ZrSi₂, B₄C and C. Highly dense composites with homogeneously intermixed ultra-fine (Zr, Hf)B₂ and SiC grains (100–300 nm) were obtained after RSPS at 1600 °C for 10 min. The densification was promoted by high energy ball milling and ZrSi₂ additive. The additives were almost completely transformed into ZrB₂ and SiC during densification. The improvement of flexural strength and fracture toughness (641 MPa and 5.36 MPa m^1/2, respectively) was achieved. The relationships between the ultra-fine microstructure and mechanical properties were discussed.     

超滤法分离纯化刺参酸性粘多糖工艺研究

探索了超滤法分离纯化刺参酸性粘多糖的工艺.确定分离纯化条件为:采用截留分子量8 kDa的超滤膜,压力为0.3 MPa,温度为10℃.此工艺制得多糖纯度为93.4%、收率为0.32%,多糖截留率达到97.2%.     

Antibiotic and antifouling compound production by the marine-derived fungus Cladosporium sp. F14

A marine-derived fungus, Cladosporium sp. F14, was studied for its ability to produce antibiotic and antifouling compounds on different cultivation media. The fungus grew well on tryptone or yeast extract media, slowly on ammonium or nitrate media, and not at all on urea media. In nutrient-enriched cultivation media, this strain produced antibiotic and antifouling compounds in the presence of glucose or xylose. These bioactive compounds were rarely produced in the absence of the sugars, even though the fungal cells grew well under these conditions. Fungal extracts decreased the attachment of bryozoan larvae (Bugula neritina) and showed antibiotic activity towards 6 tested bacterial species. Metabolite profiles of the fungus revealed by gas chromatography – mass spectrometry (GC–MS) showed clear differences when glucose was present in or absent from the culture medium. This study provides another evidence that marine fungus has the ability to produce antibiotic and antifouling compounds.     

测井用电动挤压式橡胶集流器集流性能分析

针对常规测井用集流器存在的漏失、易刮破等问题,提出一种以橡胶弹性件为核心的电动挤压式橡胶集流器整体方案。该方案利用有限元法和Mooney-Rivlin超弹性本构模型,对所提橡胶弹性件进行仿真,研究了其形状、几何尺寸以及材料属性等对集流性能的影响规律。研制了电动挤压式橡胶集流器,在模拟井实验平台上测试其集流性能。实验结果表明,橡胶弹性件形状、硬度、与套管之间的摩擦系数、内凹程度均对其受力形变性能有显著的影响;采用硬度58HA、尺寸80mm×12mm、内凹量4mm、圆弧内凹型弹性件的橡胶集流器,其集流性能优于常规伞式集流器。     

沈阳市未来城市扩展模拟预案研究

利用基于遥感手段获取的沈阳市城市发展历史数据对SLEUTH模型进行校正,对未来（2005-2030年）的城市扩展过程进行不同生态环境保护政策下的情景模拟,并对其扩展格局和生态环境影响进行分析与比较。结果显示,未来沈阳市城市化进程将进入一个加速发展阶段;2016年以后各政策预案条件下的城市扩展格局和可持续性呈现出明显的差异;目前趋势发展预案（Ⅰ）下,城市扩展导致大量的土地资源被侵占,城市景观格局日益复杂化;环境保护发展预案（Ⅱ）和生态可持续发展预案（Ⅲ）下城市扩展空间受到较大约束,部分自然资源得以保护,城市扩展格局在模拟期内相对比较紧凑;研究表明必须采取严格的城市规划与增长管理措施,引导和控制沈阳市未来城市扩展,保护基本农田和城市生态支撑系统;SLEUTH模型为城市土地资源可持续利用提供了一种有用的规划工具。     

基于MODIS NDVI的中国东部植被覆盖时空变化特征

基于2001~2010年逐月MODIS NDVI产品,采用Mann-Kendall检验和Hurst指数,研究中国东部及5个子区(东北区、黄淮海区、长江中下游区、江南区和华南区)植被覆盖的时空动态特征。结果表明:10 a期间中国东部植被覆盖以不显著改善和不显著退化特征为主,前者稍占优势,4个季节中秋季改善状况最显著;未来态势主要表现为不显著改善且未来将持续改善和不显著退化且未来将持续退化两种特征。植被覆盖为不显著退化且将持续退化的区域主要分布在大型城市或城市群周围;5个子区中,除江南区年内主要表现为不显著退化且将持续退化特征外,其余4区均主要表现为不显著改善且未来将持续改善特征。     

Using the normalized peak area of remote sensing reflectance in the near-infrared region to estimate total suspended matter

The normalized peak area (NPA) of remote-sensing reflectance (R _rs) in the near-infrared region was used to estimate the concentration of total suspended matter (C _TSM) in coastal waters. A linear regression model between C _TSM and S _NPA (R ²?=?0.83) was established, where S _NPA is the area encompassed by the reflectance curve and the straight line between wavelengths 768 and 840 nm where there is a maximum of R _rs near 715 nm. In the Pearl River estuary of South China, this NPA model performed better than other single-band and multi-band regression models, with a root mean square error (RMSE) of 4.07 mg l^–1. This model may be widely applied to in situ measurements of TSM.     

一种基于均值的多维样本空间分类器的设计与实现

分类算法是机器学习的一个重点,是有监督的学习。论文设计并实现了一种基于均值的多维样本空间分类器。对每个训练样本属性,计算该属性的类别X平均值和非类别X平均值的中值,作为类区分值,构建分类器;并进行分类测试,小于分离值的计为类别X,大于分离值的计为非类别X。然后根据类别X和非类别X属性的个数,由多数方决定最后的类别预测;最后以美国加州大学埃尔文分校的机器学习库中的乳腺癌病人肿瘤组织属性数据为样本进行实验。实验表明该分类器简单易行,准确率高。     

惯导仿真训练系统的研究

采用面向对象的软件建模思想、模块化的软件设计思想和多种相关技术,设计实现了"惯性导航仿真训练系统"。该系统是一个能训练领航员熟练操作惯导及领航技能的软硬件结合的仿真训练系统。文章对系统的设计原则、构成及实现方法进行了阐述,给出了测试航线图,并实现了与其他模拟器的组网对接。