基于EEMD的盐城大丰区降水量时间序列多尺度分析

[目的]研究盐城大丰地区年降水量时间序列规律。[方法]基于集合经验模态分解(EEMD)的数据处理方法,通过Hilbert变换对降水量数据进行多尺度特征研究,并对研究结果进行显著性和误差检验。[结果]近55 a盐城大丰地区年降水量序列可以分解成4个IMF分量和1个趋势分量;主要存在0~0.05和0.45~0.50 Hz 2个频率区间,其间主周期为2.12 a年际周期和27.50 a年代际周期,二者均通过95%显著性检验。EEMD可以有效地重构原始降水量数据变化曲线,与原始数据对比误差百分比始终控制在±0.6%范围内,由白噪声带来的干扰误差几乎可以完全忽略。[结论]该研究可为合理开发与充分利用水文资源、防汛抗旱等提供科学依据。     

鲁西南地区主要气象灾害时空分布特征分析

在气候变暖的背景下,气象灾害频繁发生。为了达到趋利避害、防灾减灾的目的,本文利用鲁西南地区7县2区的多年的气象站的观测资料,选取了1971—2010年的地面气象站的观测数据和历史气象灾害灾情数据,分析了鲁西南地区的主要气象灾害,简述了暴雨、雷电、大风、冰雹这四种气象灾害的时间和空间空分布特征,为鲁西南地区气象灾害防御提供了科技支撑和理论支持。结果表明: 暴雨日数随着年代的增加呈现出上升的趋势,空间分布总体呈纬向的自北向南递增趋势;雷电日数随着年代的增加总体呈逐年减少的趋势,空间分布由牡丹区逐渐向各县递减;冰雹发生次数呈减少的趋势;大风日数呈现出明显的下降趋势。     

Comparison of empirical and partly deterministic methods of time domain reflectometry calibration, based on a study of two tropical soils

The use of time domain reflectometry for the determination of volcanic soils' moisture content in tropical areas has shown the necessity to set up an accurate calibration. We chose to test the most representative calibration models on two tropical volcanic soils coming from two different climatic areas of the Réunion Island. The empirical model of Topp et al. [Topp, G.C., Davis, J.L., Annan, A.P., 1980. Electromagnetic determination of soil water content: measurements in coaxial transmission lines. Water Resources Research, 16 (3) 574–582.] was found to offer the best accuracy/simplicity trade-off for simulations with a cambisol, with an accuracy of ±2.46 dielectric constant points (or about ±2.7% for a water content close to 45%). In contrast, it gave poorer results for analysis of the andosol containing the greatest quantity of amorphous minerals (±5.74 dielectric constant points). The partly deterministic models were found to be better for this latter application, including that of Ansoult et al. [Ansoult, M., De Backer, L.W., Declercq, M., 1985. Statistical relationship between apparent dielectric constant and water content in porous media. Soil Sci. Soc. Am. J., 49, 47–50.] which gave the best accuracy (±3.84 dielectric constant points). For both soil materials studied, there was only a slight gain of accuracy by introducing a specific polynomial calibration determined in the laboratory: ±1.72 and ±3.46 dielectric points for the cambisol and the andosol, respectively. Choices of models to be used should thus be based on the type of soil to be analysed and accuracy requirements.     

Medium-term gully headcut retreat rates in Southeast Spain determined from aerial photographs and ground measurements

This paper deals with gully retreat rates at different time scales, whereby the short-term time scale may span a time interval of 1–5 years, the medium-term time scale a time interval of 5–50 years, and the long-term time scale a time interval of more than 50 years. An analysis of high-altitude aerial photographs in combination with ground measurements allowed us to quantify volumetric gully-head retreat rates for 12 permanent gullies in Southeast Spain (Guadalentin and Guadix study areas) over a 40–43 year time interval (medium-term time scale). This resulted in an average retreat rate (V_e) of 17.4 m³ year⁻¹. A power relationship between drainage-basin area (A) and medium-term volumetric gully-head retreat rate, V_e=0.069A^0.380 (R²=0.51, n=21), was found by combining the gully-head retreat rates obtained in this study with those obtained by a dendrochronological method. The exponent (b) and the coefficient of determination (R²) of the power relationships V_e=aA^b increases from the short-term to the long-term time scale, expressing the increasing importance of drainage-basin area in gully development with time. Considerable differences between gully-head retreat rates measured at the short and medium-term time scales at individual gullies showed the importance of land-use changes and unsuccessful management practices on gully-head retreat, and the episodic nature of gully-head retreat when piping and tension cracking are involved. Higher gully-head retreat rates are obtained at the medium-term time scale compared to the short-term time scale but the differences are not significantly different at α=10%. The medium-term methods tend to measure proportionally more high gully retreat rates, but less extreme values compared to the short-term method. This is explained by a more equal distribution of extreme rainfall events both in space and time at a longer-term time scale, and hence a higher probability of measuring the average effect of both small and extreme rainfall events at each gully.     

杂交稻新组合钱优817特征特性及高产制种技术探讨

在介绍连晚优质抗病杂交稻新组合钱优817及其亲本特征特性的基础上,总结了钱优817高产制种技术措施,包括适时播种、确定合适的行比和行株距及提高异交结实率等方面。     

利用SPME-GC×GC/TOFMS对香草兰中挥发、半挥发性成分萃取与分析研究

利用固相微萃取(SPME)法萃取香草兰中挥发和半挥发性的成分,再结合全二维气相色谱/飞行时间质谱(GC×GC/TOFMS)技术进行定性分析。试验共鉴定出香草兰中181种挥发、半挥发性化合物,其中含量较高的成分主要有香兰素、呋喃甲醛、(2S,3S)-(+)-2,3-丁二醇、邻甲氧基苯酚、2,3-丁二醇、苯酚、正己醛、(2R,3R)-(-)-2,3-丁二醇、对羟基苯甲醛、3-甲基丁酸、2,3,5,6-四甲基吡嗪、3-羟基-2-丁酮、香草酸、壬醛、正己酸、1-辛烯-3-酮。结果表明,GC×GC/TOFMS高分辨率和高灵敏度的特点非常适合复杂组分体系的定性分析。     

台州市环境空气质量与气象条件分析及神经网络预报

首先对浙江台州市近3年空气污染物PM10、SO2和NO2浓度的时间分布进行统计分析,并分析气象条件包括气压、相对湿度（高空露点温度）、气温、风速和大气稳定性等变化与空气污染物浓度扩散的相关关系,得到与污染物浓度相关的几个因子,用多元回归法和径向基神经网络（RBF）进行建模,并对2003年9-10月进行试报,取得较好效果,可作为台州市环境空气污染日平均浓度预报的参考手段。     

豫东潮土区夏玉米高产创建简化施肥技术应用效果

为实现豫东潮土区夏玉米高产和简化施肥,采取田间试验示范研究了专用缓释肥对夏玉米产量、经济效益及抗逆性的影响。周口市商水县潮土区试验点的结果表明：缓释氮比例占45%的专用缓释肥有利于提高千粒重和穗粒数,较习惯施肥,千粒重提高28 g,穗粒数增加16 粒。缓释肥促进了夏玉米对养分的吸收利用,可维持土壤氮素养分平衡,增产增效显著,较习惯施肥,应用缓释肥暨种肥同播技术,增产13.5%,增效1920 元/hm2;较普通肥料增产10.3%,增效1215 元/hm2。该研究为周口市大面积在玉米生产上推广缓释肥提供依据。     

吉林省森林火灾释放碳量的时间变化规律

根据吉林省1969-2004年的森林火灾统计数据,计算出吉林省森林火灾年均释放碳22004.38～29339.17t,约占全国年均森林火灾排放碳的1.05%.用排放比法得出吉林省年平均森林火灾释放的CO2、CO、CH4量分别为72614.45～96819.27、5283.01～7044.02和1784.40～2379.20t.吉林省森林火灾碳和含碳气体释放最多的月份是9月,占总释放量的60.6%,其次为10、5和4月,分别占总释放量的16.1%、11.4%和9.8%.吉林省森林火灾碳和含碳气体释放最多的时间段是13:00-13:59,占总释放量的31.4%,其次是14:00-14:59、15:00-15:59和11:00-11:59,分别占总释放量的18.7%、16.4%和16.0%.     

遥操作机器人存在时延的位置控制研究

以电液伺服遥操作主从机器人为控制对象 ,在系统存在时延的条件下 ,实现机器人从动机械手位置和姿态行程跟随主手操纵柄位置的控制。通过建立电液比例阀控制不对称液压缸的数学模型 ,分析了 Smith数字控制器的原理和实现方法 ,并与传统的控制方法进行了对比研究。针对不同时延进行了仿真试验 ,仿真结果表明 ,该方法对电液伺服遥操作机器人的位置控制具有良好的效果和较强的鲁棒性 ,证明了方法的有效性