关于Diophantine方程的解

对于正整数a ,设S(a)是Smarandache函数。证明了 :方程S(1·2 ) +S(2·3) +… +S(x(x +1) ) =S(x(x +1) (x +2 ) /3)仅有正整数解x =1。     

对应分析在法国Douarnenez海湾拟庸鲽食性研究中的应用(Ⅱ)

２．４拟庸蝶食性的对应分析２．４．１观察量和变量的分组观察量（捕食鱼类）依不同季节（冬、夏季）、不同性别（雌雄性）和不同性成熟状态（幼鱼和成鱼）来分组，因此得到８（２３）个观察量。对应分析的变量（饵料）首先根据个体生态的不同分为６个类型：游走多毛类，隐居多毛类，双壳类，不大游动的甲壳类（端足目和等足目），爬行甲壳类（十足国短尾部）和棘皮动物。其他６个类型的饵料生物（类、纽虫类、小型游泳甲壳类、腔肠动物、鱼类及苔藓虫类顺在分组时剔除，其原因为它们的出现可能少了些。考虑到捕食鱼类和饵料双壳类贝壳厚度…     

数字水准仪标尺编码原理研究

数字水准仪的标尺编码规则直接影响其测量精度.基于现有几种数字水准仪标尺编码的特点,归纳出标尺条码的编码衡量指标:信息密度、分辨率和纠错能力.以条码的最大编码容量与单个码区长度之比值衡量其承载的信息密度;利用光学系统的点扩散函数研究条码图像的分辨率,即相邻边缘的相互影响,得出码元相邻边缘的间距相等时,影响最小的结论;用相关系数或编码所用函数本身的性质表征条码的纠错能力.依据编码指标建立一套新的标尺编码规则:以格雷码为数值码,固定宽度的码元为参考码,两者交替组合.分析表明,该种编码不但信息密度大,分辨率高,而且纠错能力强.     

Surface renewal analysis for sensible and latent heat flux density

High frequency temperature measurements were recorded at five heights and surface renewal (SR) analysis was used to estimate sensible heat flux density (H) over 0.1 m tall grass. Traces of the temperature data showed ramp-like structures, and the mean amplitude and duration of these ramps were used to calculate H using structure functions. Data were compared with H values measured with a sonic anemometer. Latent heat flux density (E) was calculated using an energy balance and the results were compared with E computed from the sonic anemometer data. SR analysis provided good estimates of H for data recorded at all heights but the canopy top and at the highest measurement level, which was above the fully adjusted boundary layer.     

Origin of iodine in volcanic fluids: I results from the Central American Volcanic Arc

The largest reservoir of crustal iodine is found in marine sediments, where it is closely associated with organic material. This presence, together with the existence of a long-lived, cosmogenic radioisotope ¹²⁹I (t_1/2 = 15.7 Ma), make this isotopic system well suited for the study of sediment recycling in subduction zones. Reported here are the results of ¹²⁹I/I ratios in volcanic fluids, collected during a comprehensive study of fluids and gases in the Central American Volcanic Arc. ¹²⁹I/I ratios, together with I, Br, and Cl concentrations, were determined in 79 samples from four geothermal centers and a number of crater lakes, fumaroles, hot springs, and surface waters in Costa Rica, Nicaragua, and El Salvador. Geothermal and volcanic fluids were found to have iodine concentrations substantially higher than values in seawater or meteoric waters. ¹²⁹I/I ratios in most of the geothermal fluids are below the preanthropogenic input ratio of 1500 × 10⁻¹⁵, demonstrating that recent anthropogenic additions are largely absent from the volcanic systems. The majority of the ¹²⁹I/I ratios are between 500 and 800 × 10⁻¹⁵. These ratios indicate minimum iodine ages between 25 and 15 Ma, in good agreement with the age of subducted sediments in this region. In all four geothermal systems, however, a few samples were found with iodine ages older than 40 Ma—that is, considerably below the expected age range for subducted sediments from the Cocos Plate. These samples probably reflect the presence of iodine derived from sediments in older accreted oceanic terraines. The iodine ages indicate that the magmatic end member for the volcanic fluids originates in the deeper parts of the subducted sediment column, with small additions from older iodine mobilized from the overlying crust. The high concentrations of iodine in geothermal fluids, combined with the observed iodine ages, demonstrate that remobilization in the main volcanic zone (and probably also in the forearc area) is an important part in the overall marine cycle of iodine and similar elements.     

Landslide detection and susceptibility mapping using LiDAR and an artificial neural network approach: a case study in the Cuyahoga Valley National Park,Ohio

The purpose of this study was to detect shallow landslides using hillshade maps derived from light detection and ranging (LiDAR)-based digital elevation model (DEM) derivatives. The landslide susceptibility mapping used an artificial neural network (ANN) approach and backpropagation method that was tested in the northern portion of the Cuyahoga Valley National Park (CVNP) located in northeast Ohio. The relationship between landslides and predictor attributes, which describe landform classes using slope, profile and plan curvatures, upslope drainage area, annual solar radiation, and wetness index, was extracted from LiDAR-based DEM using geographic information system (GIS). The approach presented in this paper required a training study area for the development of the susceptibility model and a validation study area to test the model. The results from the validation showed that within the very high susceptibility class, a total of 42.6 % of known landslides that were associated with 1.56 % of total area were correctly predicted. In contrast, the very low susceptibility class that represented 82.68 % of the total area was associated with 1.20 % of known landslides. The results suggest that the majority of the known landslides occur within a small portion of the study area, consistent with field investigation and other studies. Sample probabilistic maps of landslide susceptibility potential and other products from this approach are summarized and presented for visualization to help park officials in effective management and planning.     

云南永善县茂林铜矿铜元素赋存状态研究

云南永善县茂林铜矿属于玄武岩型铜矿,品位较低.通过电子探针、化学多元素分析以及光、薄片镜下观察等研究,对矿石的结构、构造,铜矿物在矿石中的赋存状态都有了清楚认识.研究结果显示约68％的铜以独立矿物的形式赋存在赤铜矿和自然铜中,另有32％的铜则以类质同像的形式赋存在绿泥石中.     

南海北部浮游植物生物量的研究特点及影响因素

介绍了浮游植物生物量变化的研究方法。综述了南海北部浮游植物生物量在营养盐、光照、季风等理化因子影响下出现的变化特点。该海域生态环境复杂,由富营养的珠江口、沿岸带、北部湾和广阔的陆架及贫营养的开阔海区等不同生态区组成,因此浮游植物群落和生物量有其自身复杂的空间和时间变化特点。     

落物撞击作用下海底管道风险评估

海洋平台吊机起吊货物频繁,落物事故偶有发生,对平台附近的海底管道造成危害。在DNV推荐方法的基础上,改进了碰撞概率的计算方法。运用概率统计的方法以及失效概率理论编制Matlab程序,充分考虑各因素不确定性基础上,对落物撞击作用下海底管道进行了风险评估及敏感性分析。为减少落物对海底管线的损伤,及如何配置合理的防护措施提供了科学依据。     

2006年秋季长江口及邻近海域微微型浮游生物的分布特征及环境影响因素

2006年10月在长江口及邻近海域采用流式细胞技术测定了微微型浮游生物:聚球藻Synechococcus、微微型光合真核生物(picoeukaryotes)和异养浮游细菌(heterotrophic bacteria)的丰度和碳生物量,研究了其生态分布特点,并分析了其与环境因子之间的关系.结果表明,聚球藻、微微型光合真...