Chaos in a Bose-Einstein condensate

It is demonstrated that Smale-horseshoe chaos exists in the time evolution of the one-dimensional Bose--Einstein condensate driven by time-periodic harmonic or inverted-harmonic potential. A formally exact solution of the time-dependent Gross-Pitaevskii equation is constructed, which describes the matter shock waves with chaotic or periodic amplitudes and phases.     

N-羧甲基壳聚糖的制备及结构表征

以壳聚糖为原料,与乙醛酸作用形成希夫碱,在强碱性条件下经NaBH4还原制得N-羧甲基壳聚糖。此制备方法产率可达90%,羧甲基度达65%;反应时间短,步骤简单,降低了制备成本。采用红外光谱及核磁共振波谱法对产物结构进行了表征。     

近50年来南海海面蒸发量的时空变化特征分析

根据最新的OAFlux洋面蒸发量资料,使用EOF经验正交分解、谐波分析、小波变换、功率谱分析、趋势分析、M-K检验等方法,对南海海区蒸发量的时空特征进行了分析.结果表明:1)南海地区的蒸发量空间分布上秋冬季节最强,其次是盛夏季节,而春季最弱.2)南海海面蒸发量表现为全区一致变化型和南北反相变化型两个主要模态,并可以解释总方差 60%以上的变化.3)在2-5 年周期的年际变化尺度上,南海海面蒸发量与12-2月Ni(n)o3.4区海温距平存在较大相关.距平合成分析表明,在强La Ni(n)a年,南海海面蒸发表现南北蒸发反相变化型,南海北部为正距平区,南部为负距平区;而在强El Ni(n)o年,整个南海几乎全为正距平区.4)南海海面各个季节的蒸发量空间分布形态都存在高频的2-5年的年际变化和低频的10-14年的年代际变化,这些周期振荡在南海海面蒸发量演变的不同阶段显著性不一.5)不仅从多年平均的年际变化上看南海海面蒸发量在1997年发生突变,而且四季的蒸发量也均在1980年代后期发生过由偏弱转为偏强的突变.     

离子色谱法同时测定嗜热厌氧菌发酵液中的有机酸与无机阴离子

建立了一种利用离子色谱法同时测定甲酸、乙酸、乳酸、丙酸、丁酸5种有机酸及PO4-3、SO4-2、NO3-、Cl-、F-5种无机阴离子的方法。样品通过过滤、预柱处理后用IonPac AS11柱分离,以自动淋洗液发生器生成的KOH为淋洗液进行梯度洗脱,建立了优化的洗脱程序。用抑制型电导检测器检测有机酸的相对标准偏差为0.73%~1.01%,加标回收率为88.1%~100.2%;无机阴离子的平均相对标准偏差为2.03%,加标回收率为92.6%~101.1%,该方法可用于嗜热厌氧菌发酵液中低分子的有机酸和无机阴离子的同时测定。     

宇宙射线中子法土壤水分监测在不同生态系统雨季的适用性

宇宙射线中子法是目前测量中尺度土壤水分的一种新兴方法,通过监测近地表附近中子的数量来监测土壤含水率,理论探测深度12～76 cm。为了评估宇宙射线中子法土壤水分监测在草地、农田和林地3种不同生态系统测量深度适用性和对降水的敏感性。本研究分析了中国气象局自动土壤水分站观测数据和遥感土壤水分监测数据与宇宙射线中子法土壤水分监测数据差异性和相关性。结果显示,宇宙射线中子法土壤水分监测草地0～20 cm效果最优,农田和林地0～30 cm最优;在农田和林地生态系统土壤水分监测结果与自动土壤水分站点差异较小,优于遥感监测;但对于草地生态系统,宇宙射线中子法土壤水分监测结果与遥感监测结果差异比单点自动土壤水分站点监测更小,可能与草地土壤的强异质性有关。宇宙射线中子法土壤水分监测在草地、农田和林地生态系统均可以敏感的响应降水事件,较点尺度自动土壤水分站更易捕捉到区域水分的波动性变化。     

L g Coda Q Variation across the Myanmar Arc and its Neighboring Regions

Regional seismograms were collected to image the lateral variations of L _g coda Q at 1 Hz (Q ₀ ) and its frequency dependence η across Burma and its neighboring regions. The data include 660 vertical-component traces recorded at 39 stations. The resulting image indicates that L _g coda Q, at a frequency of 1 Hz, varies between 100 and 500. Lowest Q values (< 200) lie in the Three rivers (the Jinshajiang River, Nujiang River, and Lancangjiang River) area of Southwest China. Relatively low Q values (200–250) are found in the Himalayan region and the eastern Burma highland. Higher L _g coda Q values (> 250) are found in the eastern Indian block. From the L _g coda Q tomography, we found that (1) The Sagain fault acts as a rough boundary between the eastern Indian plate and the Three rivers area of the Eurasia plate; (2) near the eastern Himalayan syntaxis, higher Q value appears in the background of relatively low Q (which may be the consequence of the northward intrusion of the Assam block of the Indian plate into the southern Qinghai-Tibet plateau.     

Slope runoff study in situ using rainfall simulator in mountainous area of North China

Simulated rainfall is a valid tool to examine the runoff generation on the slope.13 simulated rainfall experiments with different rainfall intensities and durations are completed in a 5 m ×10 m experimental plot in mountainous area of North China.Simultaneously,rainfall,surface runoff,soil-layer flow,mantel-layer flow and soil moisture are monitored respectively.From the results,it is found that the hydrographs in all layers have the characteristics of rapid rise and fall.The recessions of surface flow and soil-layer flow are much faster than that of mantel-layer flow.Surface flow,the main contributor,makes up more than 60% of the total runoff in the study area.It even exceeds 90% in the cases of high intensity rainfall events.Runoff coefficient(ratio of total runoff to rainfall amount) is mainly influenced by rainfall amount,rainfall intensity and antecedent soil moisture,and the relationship can be well expressed by a multiple linear regression function α = 0.002P + 0.182i + 4.88Wa-0.821.The relation between the rainfall intensity and the lag time of three flows(surface runoff,soil-layer flow and mantel-layer flow) is shown to be exponential.Then,the result also shows that the recession constant is 0.75 for surface runoff,is 0.94 for soil-layer and mantel-layer flow in this area.In this study area,the dominant infiltration excess runoff is simulated by Horton model.About 0.10 mm/min percolation is observed under the condition of different rainfall intensities,therefore the value is regarded as the steady infiltration rate of the study area.     

辽河西部凹陷欢喜岭地区沙河街组三段层序地层与沉积相研究

利用高分辨率层序地层学方法,结合岩芯、测井和地震资料,识别辽河西部凹陷欢喜岭地区各级层序界面,建立地层层序格架,探讨地层格架下沉积相类型、演化规律以及平面展布,并就有利沉积相带分布进行了讨论。结果表明:从钻测井资料看出,层序界面识别标志主要为岩性和颜色发生突变,沉积相类型发生突变,电性特征发生明显变化等;将欢喜岭地区沙河街组划分为6个三级层序,12个四级层序;沙河街组三段发育扇三角洲、湖底扇和湖泊相等沉积相类型,其中,上亚段扇三角洲发育,中亚段广泛发育湖底扇相沉积,下亚段以深湖、滨浅湖相为主,斜坡边缘发育扇三角洲沉积;沙河街组三段中亚段湖底扇相和下亚段扇三角洲相的储集物性最好,为有利沉积相带。     

闽东南沿海老红砂与晚第四纪环境演变

闽东南沿海老红砂发育较典型,分布较广,但迄今对其形成多有不同认识。论文在进行全面野外调查和一系列的室内分析的基础上,认为闽东南沿海的老红砂主要是由风吹扬海滩砂形成的,局部地方还有坡积、冲积等成因,并可划分成６～４．５万ａＢＰ和３～１万ａＢＰ两个相对较集中的形成期。末次冰期寒冷干燥的气候为老红砂的形成提供了有利条件,末次冰期中的亚间冰期和冰后期温暖湿润的古气候环境则有利于其后的固定（红化固结、生草、发育古土壤等）。海面的升降变化在一定程度上控制了老红砂的物源和时空分布     

Geodetic measurement of horizontal strain across the Red River fault near Thac Ba, Vietnam, 1963–1994

Geodetic measurements from 1963 through 1994 are used to estimate horizontal strain rates across the Red River fault near Thac Ba, Vietnam. Whether or not this fault system is currently active is a subject of some debate. By combining: (1) triangulation from 1963, (2) triangulation in 1983, and (3) Global Positioning System (GPS) observations in 1994, horizontal shear strain rates are estimated without imposing any prior information on fixed stations. The estimated rates of shear strain in ten triangular subnetworks surrounding the fault trace are not significantly different from zero at 95% confidence. The maximum rate of dextral shear is less than 0.3 μrad/year in all but one of the triangles. The estimates help bound the slip rate in a simple elastic dislocation model for a locked, vertical strike-slip fault. By assuming a locking depth of 5–20 km, the most likely values for the deep slip rate are between 1 and 5 mm/year of right-lateral motion. These values delimit the 23% confidence interval. At 95% confidence, the slip rate estimate falls between 7 mm/year of left-lateral motion and 15 mm/year of right-lateral motion. Received: 18 November 1997 / Accepted: 28 January 1999