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281.
介绍了克服海浪数据低频零飘现象的一种高通数字滤波实用方法,该方法引自参考文献[1]。文章对文献[1]中提出的脉冲响应序列作了切合实际的修改,还对数字滤波器长度提出了一个适合于海浪数据处理的经验公式。近年来几个航次海上波浪测量的实际应用表明,高通数字滤波的效果是令人满意的。  相似文献   
282.
在伊朗SK500m探层钻孔施工中,采用PHP-CMC凝胶低固相泥浆顶漏钻进覆盖层,以清水和金刚石单动双管取心钻具钻进试验段,进行压水试验后,一周 用PHP-CMC凝胶无固相冲洗液护壁钻进至终孔,并利用泵压注浆水加固孔壁,较好地解决了防斜,堵漏止涌以及取心困难等技术问题  相似文献   
283.
The standard FFT analysis was applied to thirteen pulsation events selected from the March–April 1993 simultaneous measurements in space (Freja satellite) and on the ground (Niemegk Observatory). The spectral processing of the six-minute sections of record in two coordinate components perpendicular to the magnetic field lines had two principal subjects in view: a) Frequency-amplitude satellite-ground relations. The average values of smoothed spectral amplitude transmission coefficients in the total Pc4-3 and, separately, in Pc4 and Pc3 bands were 0.60, 0.48 and 0.70, respectively. The maximum values were observed within the Pc3 band, near f 30 mHz. b) Estimation of frequency bands of field line resonances (FLRs) recorded on Freja. Freja's motion in a broad latitude range (±5° around Niemegk) during the measurements enabled two frequency bands of FLRs with a width of 10's of mHz to be identified on Freja. The weighted frequencies of the FLRs bands on Freja were f wA 36 mHz and f wB 18 mHz with fine structure separations of about 5 mHz and 4 mHz, respectively. The second band with f wB 18 mHz was mostly not observed at Niemegk, and this could be the consequence of the satellite moving partly through regions of L greater than that of Niemegk.  相似文献   
284.
采用淀粉凝胶电泳技术研究了青岛近海毛蚶自然群体的等位基因酶遗传变异。在十二种等位基因酶中共检测到了二十七个基因座位,多态位点比例为51.85%,位点有效等位基因数分布从1.030…2.577(平均值1.381±0.345),位点杂合度观察值分布为0.029…0.612(平均杂合度0.133±0.036),在六个基因座位上存在相当明显的杂合子缺失现象。文中讨论了杂合子缺失的原因。  相似文献   
285.
The problem of predicting dependence of constant pressure batch dewatering of particulate suspensions on feed solids concentration is considered. Scaling transformations which demonstrate that evolution in the cake consolidation stage of dewatering is governed by an underlying self-similar behavior are proposed. The self-similar master curve, which can be obtained using only one set of experimental dewatering data obtained with a feed suspension having solids concentration above the gel point, is employed for estimating dependence of key dewatering process parameters on feed solids concentration. Using the parameter estimates in a Darcy's law based dewatering model, it is shown that the complete evolution of dewatering for a desired feed solids concentration can be predicted with reasonable accuracy. The approach is simpler to implement in comparison to available pressure filtration models, which require several suspension characterization experiments.  相似文献   
286.
The Kuihe River is in Xuzhou, Jiangsu, China. It contains high concentrations of nitrogen. The water in the Kuihe River recharges the groundwater via riverbank filtration (RBF) along the Xucun and Huangqiao reaches, which are characterized by unsaturated and saturated percolations, respectively. The two sections were selected to study the effectiveness of RBF to the nitrogen removal from the infiltrating river water. The results showed that the RBF in the saturated percolation had the potential to remove the nitrogen through biochemical processes. The nitrogen-removal rates were more than 95% over the monitoring period. However, the RBF in the unsaturated percolation resulted mainly from the physical process and thus had no efficacy for nitrogen removal.  相似文献   
287.
李晓  杨立中  魏民 《矿物岩石》2004,24(4):111-114
渗滤取水净水机理主要是利用砂砾石层表面的泥膜及砂砾石层本身过滤作用、吸附作用,微生物的降解作用达到去除水中的悬浮物质、降低水的浊度、除菌的效果。通过分析重庆江津白沙渗滤取水工程中渗透水水质表明,河水经过天然河床渗滤处理,其中的悬浮物质几乎可以被完全去除,并有较好的除菌效果。渗透水中NO3^-,COD,BOD,TOC去除率达75%以上。渗透水常量化学组分Na^ ,Cl^-浓度明显降低,Ca^2 ,Mg^2 ,HCO3有少量增加。渗滤水的水质得到大幅提高,不仅达到国家饮用水标准.而且由于水岩相互作用,使渗滤水矿化度也有所增加,产生一定矿化作用。  相似文献   
288.
In current palaeodietary research, gelatinization is the main method to extract insoluble collagen(ISC) from ancient bones. However, the degradation products of ISC, i.e., soluble collagen(SC), is often neglected and abandoned. In this work, we try to separate the extracts of ancient bones using gel chromatography and compare the contents of carbon and nitrogen, atomic C/N ratio, and stable carbon and nitrogen isotopic values of the extracts from three peaks to determine which peak can be attributed to SC. At last, the potential application of SC in palaeodietary research is discussed based on the comparison of stable isotopic values between ISC and SC. Among the three peaks, the second with the retention time between 17.5 min and 27.5 min had the most broad peak shape, indicating that the molecular weights of proteins collected were most variable. Besides, the contents of carbon and nitrogen and atomic C/N ratio of extracts in this peak were closest to the corresponding ISC. Based on the above, we conclude that the extract in second peak is SC. More important, the δ 13C and δ 15N values of ISC and SC are very similar. For ISC and SC with atomic C/N ratios within the normal range(2.9–3.6), the mean difference of δ 13C value was only(0.3±0.2)‰(n=2) while δ 15N value was(0.6±0.1)‰(n=2). Although the atomic C/N ratios of some SC are slightly beyond the normal range, the mean differences of δ 13C and δ 15N values were still only(0.4±0.1)‰ and(0.3±0)‰(n=2) respectively. These isotopic differences are quite below the isotope fractionation in one trophic level(δ 13C values of 1‰–1.5‰ and δ 15N values of 3‰–5‰), suggesting that SC had great application potentials in palaeodietary research.  相似文献   
289.
海岸带潮滩地形具有快速变化的特点;在盐沼植被覆盖的潮滩区域,地面激光扫描仪(terrestrial laser scanning,TLS)获取地形数据受到地表植被的影响。为了研究TLS在盐沼潮滩使用的地形测量精度与盐沼植被种类、盖度的关系,本文以芦苇群落、白茅群落、互花米草群落、海三棱藨草群落4种典型海岸带盐沼植被群落为研究对象,在移动窗口法的基础上辅以聚类分析的植被滤除算法,分别从点云原始数据中恢复地表地形地貌特征。研究结果表明:1)植被盖度越高,TLS反演地形精度越低,两者负相关。2)不同植被的激光穿透能力不同:盖度大于50%时,激光无法穿透原始盖度分别为70%、65%、65%的白茅群落、互花米草群落、海三棱藨草群落,均方根误差(root-mean-square error,RMSE)分别为22.0、22.0、8.6 cm;盖度等于50%时,白茅群落、海三棱藨草群落、芦苇群落和互花米草群落的RMSE分别为16.0、6.6、4.5、5.7 cm;盖度小于50%时,芦苇群落、互花米草群落、海三棱藨草群落地形反演精度小幅度提高,白茅群落地形反演精度提升较为明显。3)在盐沼潮滩地区使用TLS反演地形时,增加TLS架设高度、对同一区域多方位反复扫描可能有助于提高地形反演效果。  相似文献   
290.
以甲氧基聚乙二醇丙烯酸酯(MPEGA)和甲基丙烯酸二甲氨基乙酯(DMAEMA)为均聚单体,通过乳液聚合制备一类新型疏水缔合型聚合物P(MPEGA-DMAEMA),采用FT-IR和1HNMR表征新型聚合物的化学结构;利用主剂P(MPEGA-DMAEMA)和交联剂醋酸铬形成凝胶体系,考察主剂P(MPEGA-DMAEMA)和交联剂醋酸铬的质量分数、pH值、温度、矿化度对新型聚合物凝胶体系成胶性能的影响.结果表明:当主剂P(MPEGA-DMAEMA)质量分数为1.2%、交联剂醋酸铬质量分数为0.2%、pH值为7、温度为45e时,该新型聚合物凝胶体系具有最佳的成胶强度.将新型聚合物凝胶体系应用于岩心封堵,在最佳成胶条件下,堵水率高于90%,堵油率低于40%,具有较好的选择封堵性.  相似文献   
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